THE EFFECT OF CRYOTHERAPY ON LANDING FORCES DURING A SINGLE LEG JUMP A THESIS Submitted to the Faculty of the School of Graduate Studies and Research of California University of Pennsylvania in partial fulfillment of the requirements for the degree of Master of Science By Danielle Wilson Research Advisor, Dr. Thomas F. West California, Pennsylvania 2011 ii iii ACKNOWLEDGEMENTS I would first like to say that this thesis and this year was the hardest thing I have ever done, and my biggest academic accomplishment. With that said I would like to take this opportunity to thank everyone who has helped me this year. I want to thank my mom, dad, and brothers for all of their support and believing in me, even when I thought I could not get through this year. I would also like to thank Brett for listening to me daily on the phone, whether it was smiles or tears he was always there to give support and advice. I want to also thank my friends from home and undergrad as well as the GA’s here at CalU. Without your encouragement I would have never made it through this year with my sanity intact. I would like to thank my thesis chair, Dr. West, and my two committee members, Shelly and Dr. Z for helping me with this thesis. You all have left a huge impact on my life and with all that has happened this year, I know my name will not be forgotten by you. Lastly, I would like to thank Christine Stache. Thank you so much for allowing me to use your data collection that you worked very hard on. Thank you everyone! iv TABLE OF CONTENTS Page SIGNATURE PAGE . . . . . . . . . . . . . . . ii AKNOWLEDGEMENTS . . . . . . . . . . . . . . . iii TABLE OF CONTENTS . . . . . . . . . . . . . . iv LIST OF TABLES . . . . . . . . . . . . . . . vi INTRODUCTION . . . . . . . . . . . . . . . . 1 METHODS . . . . . . . . . . . . . . . . . . 5 Research Design. . . . . . . . . . . . . . . 5 Subjects. . . . . . . . . . . . . . . . . . 6 Preliminary Research. . . . . . . . . . . . . 7 Instruments. . . . . . . . . . . . . . . . . 7 Procedures. . . . . . . . . . . . . . . . . 8 Hypothesis. . . . . . . . . . . . . . . . . 9 Data Analysis. . . . . . . . . . . . . . . . 10 RESULTS . . . . . . . . . . . . . . . . . . 11 Demographic Information . . . . . . . . . . . 11 Hypothesis Testing. . . . . . . . . . . . . . 12 DISCUSSION . . . . . . . . . . . . . . . . . 14 Discussion of Results. . . . . . . . . . . . . 14 Conclusions . . . . . . . . . . . . . . . . 18 Recommendations. . . . . . . . . . . . . . . 19 REFERENCES. . . . . . . . . . . . . . . . . . 21 APPENDICES . . . . . . . . . . . . . . . . . 24 v APPENDIX A: Review of Literature . . . . . . . . 25 Introduction . . . . . . . . . . . . . . . . 26 Cryotherapy. . . . . . . . . . . . . . . . . 27 Cryotherapy Effects on the Body Methods of Application . . . . . 28 . . . . . . . . . 30 Cryotherapy and Functional Performance. . . . . . 32 Force Production . . . . . . . . . . . . 33 Agility . . . . . . . . . . . . . . . . 34 Balance . . . . . . . . . . . . . . . . 36 Speed . . . . . . . . . . . . . . . . . 38 Fatigue . . . . . . . . . . . . . . . . . 40 Summary . . . . . . . . . . . . . . . . . . . 42 APPENDIX B: The Problem . . . . . . . . . . . . 43 Statement of the Problem . . . . . . . . . . 44 Definition of Terms . . . . . . . . . . . . . 45 Basic Assumptions . . . . . . . . . . . . . . 46 Limitations of the Study . . . . . . . . . . . 46 Significance of the Study . . . . . . . . . . . 46 APPENDIX C: Additional Methods . . . . . . . . . 48 IRB: California University of Pennsylvania(C1) . . 49 Excel Spreadsheet Data Collection(C2) . . . . . . 63 REFERENCES . . . . . . . . . . . . . . . . . 66 ABSTRACT . . . . . . . . . . . . . . . . . 71 vi LIST OF TABLES Table Title Page 1 Peak Landing Forces Dependent on Cryotherapy and Time of Test . . . . . . 13 2 ANOVA Results for Main Effects and Interaction between Cryotherapy and Time Conditions . . . . . . . . . . 13 3 Mean Peak Landing Forces: The Cryotherapy Group . . . . . . . . . . . 64 4 Mean Peak Landing Forces: The Control Group . . . . . . . . . . . . . . . 64 1 INTRODUCTION Cryotherapy is one of the most commonly used modalities in athletic training today.1-3 This modality is used frequently for acute injury treatment. Studies have shown that cryotherapy is effective in reducing pain, decreasing inflammation, and decreasing muscle spasms.1-9 Several studies have examined the effect of this modality on various measures of performance; however, there are few studies examining the effects of cryotherapy on peak landing force immediately after cryotherapy application and over the time necessary to rewarm. Force production and force absorption are critical parts of athletic performance. Being able to produce a great enough force to jump or run, then absorb that force is highly important from a performance standpoint as well as for return to play criteria. Athletes use various forms of cryotherapy such as ice bags, cold whirlpools, and ice immersion prior to, during, and after participating in athletic events. Cryotherapy has the potential to decrease force production, alter body kinematics and increase the rate of fatigue due to its 2 physiological effects on the circulatory and nervous systems. 4,6,7 Several researchers have examined the effect of cryotherapy on force production and absorption. There are conflicting findings about whether there is a decrease in landing force absorption after the application of cryotherapy. A decrease in force absorption has the potential to hinder performance prior to participating in sports. Force is defined as a generation of tension and pressure created in the body via muscle, muscle fibers, nerves and neural functioning.10 If the body is not able to produce a great enough force to jump or run, or absorb the force the body produces, it can significantly decrease athletic performance and potentially increase the risk of injury. Force production can be measured by single or double leg jumping measuring the landing ground force.11-13 Force absorption can be measured as vertical ground reaction forces (VGRF).14 Vertical ground reaction force is equal in magnitude in the opposite direction to the force that that body exerts on the supporting surface through the foot.15 However for this study, force absorption, also referred to as peak landing force, was measured by the maximum of the landing force production on the BioAnalysis analysis sheet. 3 The effects of cryotherapy on force production and absorption have conflicting findings through the literature. Jameson examined the effects of cryotherapy on vertical-ground-reaction-force during a double leg landing from a double leg vertical jump.13 Subjects jumped five times prior to cryotherapy treatment and five times after cryotherapy treatment. Subjects were placed in four conditions; no ice, ice on the ankle joint only, ice to the knee joint only, and ice to both ankle and knee joints combined. Ultimately, this study did not find a significant difference in vertical ground reaction force as a result of cryotherapy. In a study by Simon et al,10 force production was tested by means of isometric force production of the lower leg. This study suggested that subjects attempting to produce equal lower limb forces would generate equal percentages of force of their bilateral maximum voluntary strength rather than equal absolute limb forces. This study used ten male and female subjects who performed isometric extensions of the lower limb. Subjects were asked to match forces in their lower limbs at three different sub-maximal levels. It was found that subjects continually produced less force in the weaker limb during all force matching levels. 4 Force production and absorption is a major component to athletic performance with fatigue as a possible hindrance.10 If cryotherapy decreases force absorption and increases how quickly the muscles fatigue, then professionals who use this modality need to be aware of the possible effects cryotherapy has on athletic performance. Thus, the purpose of this study is to examine the effect cryotherapy has on lower extremity peak landing forces over time in college age students, which could in turn impact the athlete’s performance and injury risk. 5 METHODS The primary purpose of this study is to determine if cryotherapy effects lower extremity peak landing force during a single-leg vertical jump. The secondary purpose of this study is to examine if cryotherapy has an affect on peak landing forces over time. This section will include the following subsections: (1) research design, (2) subjects, (3) preliminary research, (4) instruments, (5) procedures, (6) hypotheses, and (7) data analysis. Research Design This is a quasi-experimental, within-subjects, research design. The study will use preexisting data from a study entitled “The Effect of Cryotherapy on Single Leg Vertical Jump” by Stache.16 For the present study, the independent variables are cryotherapy condition, tested at two levels and time tested at five levels. The first level of cryotherapy was application of an ice bag to the anterolateral aspect of the ankle. The second level was no application of cryotherapy to the anterolateral aspect of the ankle. Peak landing force was measured over time with 6 subjects performing five vertical jumps at five different times. The first level of time was a pretest, second was a posttest, third was five minutes after the posttest, fourth was ten minutes after the posttest and fifth was twenty minutes after the posttest. The dependent variable was peak landing force. The dependent variable was measured through passage of time. Maximal landing force generated in a series of five single-leg vertical jump was measured using the force platform. Subjects Stache16 used 14 healthy volunteers who were physically active individuals. Physically active was defined as being active three times a week for twenty minutes or more. Being active included cardiovascular exercise and/or strength training three or more times a week. Subjects were screened for previous conditions; lower extremity injury, head injury/concussions, neurological disorders and contraindications of ice such as cold allergies, poor circulation diminished sensations, slow healing wounds and Raynaud’s Syndrome. 7 For this present study, only 12 subjects’ from the previous study had data that could be used. The study was approved by the Institutional Review Board at California University of Pennsylvania (Appendix C1). There were no identifiers in the data to link the participants to the performance data. Each participant’s identity was kept confidential and was not included in the study. Preliminary Research Before research was conducted and after IRB approval, the researcher received the data from the previous researcher. Stache performed a pilot study on one subject, whose data also remained in the study. This preliminary study was performed to become familiar with the force platform and the amount of time that was needed for testing. Instruments The instrument that was used in this study was BioAnalysis, computer software program running on a Windows based personal computer that analyzed the force that was 8 produced on the force platform in the previous study. Stache’s16 instruments included an AMTI 6-7 force platform (AMTI Force Platform and Amplifier, Advanced Technology, Inc: Advanced Mechanical Technology, Inc. 176 Waltham Street, Watertown, MA 02472-4800 USA) to measure forces during the single-leg vertical jump. Additionally, a demographics sheet, ice bags, compression wraps and a stationary bike were used. Procedure For the previous study, Stache16 had performed data collection twice. The first day was used to complete the demographic sheet, and sign the informed consent. After this was completed the procedures were explained to the subjects. With the subjects understanding of the directions and the procedures of research, they were allowed to perform practice single leg vertical jumps on the force platform. Once the subject was comfortable with the jumps they bicycled for five consecutive minutes for a warm-up. After the warm-up, the subjects performed five pretest single-leg vertical jumps on the force platform. After the pretest the subjects participated in their cryotherapy 9 condition; cryotherapy or no cryotherapy. The subjects in the cryotherapy condition sat with an ice bag placed over the anterolateral aspect of their ankle in their dominant jumping leg for twenty minutes. When subjects were in the no cryotherapy condition, they were asked to sit quietly for twenty minutes. Immediately after the completion of the cryotherapy condition, subjects then performed five posttest single-leg vertical jumps. The subjects then sat and waited to jump five minutes, ten minutes and twenty minutes after the cryotherapy removal. For the present study, the data was collected from the previous research to elicit additional findings. The current researcher took the five sets of five jumps per subject and looked at peak landing force via BioAnalysis. Each peak landing force was put into an Excel spreadsheet (Appendix C2) to later be entered into SPSS. Hypothesis The following hypothesis was based on previous research and the researcher’s institution based on a review of the literature. 10 There will be no difference in peak landing force dependent on cryotherapy conditions and the passage of time. Data Analysis All data was analyzed by PASW version 18.0. The data was analyzed to determine if cryotherapy has an effect on peak landing force and if peak landing force is affected by time. The research hypothesis was analyzed using a 2 x 5 repeated measures factorial analysis of variance (ANOVA). An alpha level of 0.05 was used to determine statistical significance. 11 RESULTS The purpose of the study was to determine if cryotherapy and the passage of time had an effect on peak landing force during a single-leg vertical jump. Data was collected during a single-leg-vertical-jump onto a force platform in a previous study by Stache, and the data were analyzed via BioAnalysis by the current researcher. The following section includes: Demographic Information and Hypothesis Testing. Demographic Information The previous study utilized fourteen physically active California University of Pennsylvania students with a mean age of 21.8 years. Subjects consisted of five male and nine female volunteers. The subjects completed a demographic form that contained information including age, year in school, dominant leg, injury history, head injury/concussions, neurological disorders, cryotherapy use, cold allergies and contraindications. All participants had no neurological disorders or cold allergies, and were 12 symptom free of head injuries for more than a year and free of lower extremity injuries for four months. For the current study, none of the demographic information was passed on to the current researcher, therefore the subjects remained anonymous and could not be identified by any information in the data. Of the fourteen subjects used in the previous research only twelve subjects could be used in the current research due to data missing in the data files. Hypothesis Testing The following hypothesis was tested in the study. The hypothesis was tested with a significance level of α ≤ 0.05. A 2 x 5 repeated measures factorial analysis of variance was used to analyze if mean scores were different due to the independent variables. Hypothesis: There will be no difference in peak landing force dependent upon cryotherapy conditions and the passage of time. Conclusion: A 2 x 5 repeated measure ANOVA was calculated comparing cryotherapy conditions (no cryotherapy, cryotherapy) and time (pretest, posttest, five minutes, ten minutes and twenty minutes after posttest). 13 Mean performance scores for all subjects under the various conditions can be found in Table 1. Results of the ANOVA testing are found in Table 2. No significant cryotherapy x time effect was found (F(4,44)=.757, p>.05). There was also no significant main effects with cryotherapy (F(1,11)=.261, p>.05) and time (F(1,11)=.935, p>.05). Table 1: Peak Landing Forces Dependent on Cryotherapy and Time of Test Cryotherapy No Cryotherapy Time Mean (SD) Mean (SD) Pre test 3766N (1407.2) 3454 (1.007.9) Post test 3289N (1254.2) 3405 (1038.0) 5 min 3524N (1284.2) 3512 (1248.5) 10 min 3655N (1269.2) 3547 (1211.6) 20 min 3545N (1122.0) 3398 (1068.4) Table 2: ANOVA Results for Main Effects and Interaction between Cryotherapy and Time Conditions. Factor Cryotherapy Time Cryotherapy x Time df 1 1 4 df (error) 11 11 44 F 0.261 0.935 0.757 P 0.62 0.452 0.559 14 DISCUSSION The main purpose of this study was to determine if cryotherapy had an effect on single-leg vertical jump peak landing force. In addition to the main purpose, this study also determined if cryotherapy had an effect on peak landing forces over time due to a re-warming affect. The following section is divided into three subsections: Discussion of Results, Conclusions and Recommendations. Discussion of Results A single-leg vertical jump was performed by fourteen physically active subjects in a previous study to examine cryotherapy’s effect on jumping forces. The present study examined twelve of these subject’s data, via BioAnalysis, to determine if cryotherapy and passage of time had an effect on peak landing forces. This study concluded that cryotherapy had no significant effect on single-leg vertical jump landing forces. The original hypothesis of the researcher was that there would be no difference in peak landing forces dependent on cryotherapy conditions and passage of time. The results did support the hypothesis. The mean test 15 scores for peak landing force dependent on cryotherapy condition can be found in Table 1. There was no significant difference in performance due to cryotherapy treatment. This shows that the application of cryotherapy on the ankle did not cause a decrease in landing force for the singleleg vertical jump. The mean test scores for peak landing force dependent upon passage of time can be found in Table 1. There were no significant findings in the functional performance over time after the removal of cryotherapy. This shows that increasing the time after cryotherapy is removed does not decrease the landing forces in a single-leg vertical jump. The results of this study were different than that of other studies. For example, Patterson et al17 performed a study to examine if cryotherapy had an effect on single-leg vertical jumps, t-test and 40 yard dash. The results suggested that functional performance was affected immediately following cryotherapy and that there was a gradual increasing in performance over time with muscular re-warming. Surenkok et al18 assessed knee joint position and static balance after the application of cryotherapy. The results showed a significant difference in joint position sense before and after cold application. Thus, joint 16 position sense is negatively affected with cryotherapy use which will alter body balance and can adversely affect an athlete and athletic performance immediately after cryotherapy. An article by Rivers19 investigated the effects of cryotherapy on total body balance and proprioception after cryotherapy and bracing. There was a significant decrease in total body balance immediately after the cryotherapy treatment but not over time. Overall, the results from these studies varied slightly but showed that functional performance was decreased after the application of cryotherapy. Some studies did agree with the findings of the present study. Jameson et al examined the effects of cryotherapy on vertical- ground-reaction- force during a double leg landing from a double leg jump.20 Subjects were placed in four conditions; no ice, ice on the ankle joint only, ice to the knee joint only, and ice to both ankle and knee joints combined. Ultimately, this study did not find a significant difference in vertical- ground- reaction- force as a result of cryotherapy. Hart et al21 performed a study to examine the effects of cryotherapy on vertical jump measurements. Subjects performed five single-leg landings before cryotherapy. Ice 17 was placed on the anterior, lateral and medial knee for twenty minutes. After cryotherapy the subjects performed five single-leg landings immediately, fifteen and thirty minutes after treatment was removed. The results showed that there were no significant changes in ground reaction force, knee range of motion or muscle activity. Vescovi22 investigated the effects on work, velocity and power when icing the arm and shoulder between weight lifting sets. Cryotherapy between sets resulted in having a significant effect on the increased number of arm pull sets, an increase of the speed with which the sets were completed and increase in power produced during the set. Thus, interval cryotherapy decreases fatigue rate and increases work, velocity and power. The results vary for several reasons. First, the main difference is the form of cryotherapy that was applied to the body. Patterson et al17, Surenkok et al18, and Rivers19 used ice immersion or cold spray as the method of cooling. Hart et al21, and Jameson20 used crushed or cubed ice bags for a specific area of cooling. The second difference is where the ice was applied to the body. Patterson et al, selected a cryotherapy condition of ice immersion to the lower leg. Hart et al, covered specifically the anterior, lateral and medial aspects of the knee. Jameson et al chose 18 to ice the ankle and/or the knee. Lastly, the difference of the time allotted between cryotherapy and testing varied. Normally, studies use twenty minutes of testing after cryotherapy is removed to allow for the effect of rewarming. However, the studies used a passage of time that ranged from three, to ten, to twenty minutes. The decrease in testing time after cryotherapy is removed can alter the testing results because re-warming does not occur. These differences could be the reason for differing results between researchers. Conclusions The results of this study show cryotherapy has no significant effect on peak landing force over the passage of time. The significance of these results is that they allow Athletic Trainers to continue to treat athletic injuries with cryotherapy at any time during athletic performance and return athletes to play without hindering their athletic performance. There have been multiple studies that examined cryotherapy’s effect on jumping, balance, speed and agility which are all important components of athletic performance. These studies have split conclusions on the negative and 19 positive effects that cryotherapy can have on performance. Therefore, the present study alone does not conclude that an athlete can return to play immediately after the removal of cryotherapy. Thus, it is recommended that an athlete perform a warm-up before returning to play after the use of cryotherapy to decrease the chance of future injury and rewarm the muscles to better enhance athletic performance. Recommendations The results of this study show that cryotherapy did not have an effect on peak landing forces during a singleleg vertical jump. This study supports the use of cryotherapy and returning athletes to play immediately afterwards with no negative effect on athletic performance. Unfortunately, there is not a conclusive outcome in the current research to conclude that cryotherapy has no effect on athletic performance. For future research, this study could be altered and/ or advanced by testing the subjects specifically instead of analyzing previously collected data. Future study would also benefit from testing a larger number of subjects. These alterations could enhance the acceptance of the results found in the study. To improve research further, 20 cryotherapy’s effect on peak landing force can be examined by having the subjects jump from a specific height. Testing the subjects in this manner will remove the muscular fatigue that can occur during repeated eccentric contractions, such as jumping. This will allow subjects to absorb their landing force and there will be no variation in the amount of force produced during jumping between subjects. Lastly, a future researcher could increase the surface area to which cryotherapy is applied on the body to examine if increased surface area covered with cryotherapy will have an effect on force absorption. 21 REFERENCES 1. Merrick MA, Knight KL, Ingersol CD, Potteiger JA. The effects of ice and compression wraps on intramuscular temperatures at various depths. J Athl Train. 1996; 28 (3):236-245. 2. Richendoller ML, Darby LA, Brown TM. Ice bag application, active warmup and three measures of maximal functional performance. J Athl Train. 2006; 41(4):364-370. 3. Evans TA, Ingersoll C, Knight K.L, Worrell T. Agility following the application of cold therapy. J Athl Train. 1995; 30(3):231-234. 4. Merrick MA. Secondary injury after musculoskeletal trauma; a review and update. J Athl Train. 2002;37:209-217. 5. Merrick MA, Rankin JM, Anders FA, Hinman CL. A preliminary examination of cryotherapy and secondary injury in skeletal muscle. Med Sci Sports Exerc. 1999;31:1516-1521. 6. Knight KL. The effects of hypothermia on inflammation and swelling. J Athl Train. 1976;11:7-10. 7. Knight KL. Cryotherapy in sports injury management. Champaing, IL: Human Kindetics; 1995. 8. Prentice W. Therapeutic Modalities in Sports Medicine. 2nd ed. St. Louis, MO: Mosby; 1990. 9. Rubley MD, Denegar CR, Buckley WE, Newell KM. Cryotherapy, Sensation, and Isometric-force variability. J Athl Train. 2003; 38(2):113-119. 10. Cross KM, Wilson RW, Perrin DH. Functional Peformance following an ice immersion to the lower extremity. J Athl Train. 1996;31(2):113-116. 11. Simon AM, Ferris DP. Lower limb force production and bilateral force asymmetries are based on sense of effort. Exp Brain Res. 2008;187:129-138. 22 12. Gross TS, Nelson RC. The shock attenuation role of the ankle during landing from vertical jump. Med Sci Sports Exerc. 1998;20(5):506-514. 13. Prapavessis H, McNair PJ. Effects of instruction in jumping technique and experience jumping on ground reaction forces. J Orthop Sports Phys Ther. 1999;29(6):352-356. 14. Cordova M, Takahaski Y, Kress G. Influence of external ankle support on lower extremity joint mechanics during drop landings. J Sport Rehab. 2010;19:136-148. 15. Winter D. Kinematic and Kinetc patterns in human gait. Human Movement Science. 1984;3:51-76. 16. Stache C. The effect of cryotherapy on the single leg vertical jump [Master’s Thesis]. California, PA: California University of Pennsylvania; 2009. 17. Patterson S, Uderman B, Doberstein S, Reineke D. The effects of cold whirlpool on power, speed, agility and range of motion. J Sport Sci Med. 2008;7:387-389. 18. Surkok O, Ayter A, Tuzun EH, Akman MN. Cryotherapy impairs knee joint position sense and balance. Iso & Exer Sci. 2008;16(1):69-73. 19. Rivers D.A. The influence of cryotherapy and Aircast bracing on total body balance and proprioception. J. Athl Train. Microform Publications, Int'l Institute for Sport and Human Performance, University of Oregon. 1995. 20. Jameson A, Kinzey S, Hallam J. Lower-extremity-joint cryotherapy does not affect vertical ground reaction force during landing. J Sport Rehabil. 2001;10:132-142. 21. 22. Hart JM, Ingresoll CD, Leonard JL. Single-leg landing strategy after knee-joint cryotherapy. J Sport Rehabil. 2005;14:313-320. Vescovi J, McGuigan M. Relationships between sprinting, agility, and jump ability in female athletes. J Sport Sci. 2008: 26:97-107. 23 24 APPENDICES 25 APPENDIX A Review of Literature 26 REVIEW OF LITERATURE Cryotherapy is the most commonly used therapeutic and rehabilitative treatment when an acute injury is present.1 Specifically, cryotherapy is used when the goal is to decrease pain, inflammation, metabolism and swelling. Through education, cryotherapy is taught to be used after activity due to its diminishing effects on the function of the vasculature and musculature which can decrease athletic performance. Athletic performance is a combination of agility, balance, force production, speed and the body’s ability to decrease the fatigue rate.2 Without these components, athletic performance could be impaired. Furthermore, many athletes use cryotherapy before athletic performance in order to play without pain. However, it is unclear if cryotherapy decreases athletic performance to a degree at which athletic performance is significantly decreased. The purpose of this literature review is to review cryotherapy and cryotherapy’s effects on athletic performance with a focus on force production and force absorption. The following sections will describe the indications of 27 cryotherapy, cryotherapy’s effects and different methods of cryotherapy. Additionally, this literature review will debate whether or not cryotherapy has a diminishing effect on musculature by testing athletic performance and if cryotherapy can affect muscle force production over time. Cryotherapy Cryotherapy is a treatment where ice or cold application is used therapeutically. Cryotherapy is the most commonly used modality in athletics today.1-3 Athletes use cryotherapy as a rehabilitative measure daily or before practice to decrease the pain and swelling that is present from a previous or existing injury. Cryotherapy is used in the beginning phases of acute injury treatment to reduce metabolism, inflammation, and muscle spasms as well as for controlling pain.4-9 Cryotherapy has multiple effects, such as reducing nerve conduction, reducing local blood flow9, and decreasing muscle functioning.10-12 Cryotherapy also reduces tissue temperature, blood flow, pain and metabolism.13 These cooling effects on the body are mediated by conduction and convection. Conduction is heat loss or gain through direct contact with an object, such as cold pack, ice immersion, 28 ice massage, cold spray, contrast bath, cryo-cuff, or cryokinetics.14 Convection is heat loss or gain through the movement of water molecules across the skin, such as cold whirlpool.14 In regards to the treatment of cryotherapy, Bleackly et al15 reported that cold seemed to be more effective in limiting swelling and decreasing pain in the short term. Unfortunately, as stated previously there are many effects of cryotherapy but all of which are effects that are needed to control pain, swelling and inflammation. As described by Knight in Cryotherapy in Sports Injury Management, cooling the ankle joint considerably improves a patient’s ability to perform active exercise and decrease injury-recovery time.7 Cryotherapy Effects on the Body Cryotherapy’s most known effect on the body is cooling, resulting in therapeutic relief for pain. Many studies have examined how cooling takes place in the body, and all are in agreement that cooling happens when cold agents undergo a substance change; such as from a solid to a liquid.16-18 Initially the nociceptors and cold receptors will be affected by cryotherapy. This initiates the sensations of cold and pain in the body. Thermoreceptors 29 are superficial receptors that respond quickly to changes in temperature.19-22 Overall, it was found that crushed ice pack, ice massage, and cold water immersion are considered the most effective clinical modalities for reducing tissue temperature based on testing of skin and intramuscular temperatures.17,20 Cryotherapy also reduces nerve conduction velocity (NCV) in the sensory and motor nerves.21,22 Cooling decreases nerve conduction velocity, synaptic transmission, and sensory nerve action potentials.7,8,23 This means that if muscles are directly cooled, the nerves firing will not be as quick as normal and nerve impulses on the muscle will impair the muscles ability to contract as it would normally.24 Cryotherapy has other additional effects on the body such as decreased metabolism, and vasoconstriction which will ultimately decrease swelling. Cryotherapy will slow down cellular processes which will inhibit the body from repairing the damage done by the injury.25 Additional vasoconstriction occurs when the cold temperatures causes the smooth muscle to contract in the blood vessels. The smooth muscle contraction will decrease the radius of the vessel, resulting in a decreased amount of blood being able 30 to get to the area that is under the influence of cryotherapy.26 Methods of Application Cryotherapy can be applied to the body in various ways; these include, but are not limited to: cold whirlpools, ice bags, ice immersion, and chemical ice packs. These methods of application have the same indications for use but may have differing effects on the body. In a study by Pfeiffer et al, the researchers tested the effects of a 20 minute cold water immersion on neuromuscular function, rectal and skin temperature and femoral venous diameter after exercise in the heat. After the subjects completed two, 90 minute cycling periods they were either tested with a cold water immersion or a control recovery group. It was shown that rectal temperature was significantly lower in cold water immersion; skin temperature and femoral vein diameter were also significantly lower than the control recovery group from 25 to 50 minutes after the cycling trial. This study suggests that cold water immersion decreases rectal temperature but has a negative effect on neuromuscular function.16 31 In another study, Dykstra et al compared the difference of skin temperature in different cold therapies. These cold therapies included: ice pack with cubed ice, crushed ice, and wetted ice. Subjects’ intramuscular and skin temperatures were taken before and after application of the cold treatment. It was found that cubed ice and wetted ice produced lower surface and intramuscular temperatures when compared to crushed ice. Wetted ice produced a greater decrease in surface temperature.14 The outcomes of both of the articles show that ice bags are the best source of cryotherapy that will give the effects of decreased skin temperature as well as decreased blood flow to the area via vasoconstriction. With cryotherapy being the most commonly used modality in athletics today it has been shown to be effective in treating soft tissue injuries.13 As discussed previously there are many different ways to apply cryotherapy, such as ice bags, ice immersion and cold whirlpools. Each cryotherapy modality has its own specific parameters of treatment time and effectiveness, but all have been shown to decrease pain, swelling, metabolism and blood flow.13,6,9,16 32 Cryotherapy and Functional Performance Functional performance is a great testing tool done by an athletic trainer to see how athletes perform in certain physical activities such as balance, jumping, speed, agility and the ability of resist muscle fatigue. Functional performance testing is implemented to track how an athlete is progressing with and through activities by comparing functional testing outcomes. Functional performance testing can be very sports specific, which raises the question; does cryotherapy have an effect on functional performance in athletes? Cryotherapy does have its benefits as a therapeutic modality for acute injuries but these benefits can have depressive effects on the body such as nerve conduction and force production.14-16,27-29 These depressive effects can in turn have a diminishing effect on functional performance. It is the focus for this section to identify and understand specific aspects of functional performance, to identify any alternative effects on functional performance with the use of ice and how cryotherapy can affect muscular fatigue. 33 Force Production Force is a generation of tension and pressure created in the body via muscle, muscle fibers, nerves and neural functioning.30 Humans generate force in everyday activities such as walking, running, jumping, lifting and moving objects. Force production is one of the many tested aspects of functional performance in athletes. Force production can be tested by jumping and measuring single or double leg landing ground forces; eccentric loading, distal to proximal, of the lower-extremity musculature controlling joint flexion.31-33 Jameson examined the effects of cryotherapy on vertical- ground-reaction- force during a double leg landing from a double leg jump.33 Subjects jumped five times prior to cryotherapy treatment and five times after cryotherapy treatment. Subjects were placed in four conditions; no ice, ice on the ankle joint only, ice to the knee joint only, and ice to both ankle and knee joints combined. Ultimately, this study did not find a significant difference in vertical- ground- reaction- force as a result of cryotherapy. In a study by Simon et al30, force production was tested by means of isometric force production of the lower leg. This study suggested that subjects attempting to 34 produce equal lower limb forces would generate equal percentages of force of their bilateral maximum voluntary strength rather than equal absolute limb forces. This study used ten male and ten female subjects, who performed isometric extensions of the lower limb. Subjects were asked to match forces in their lower limbs at three different sub-maximal levels. It was found that subjects continually produced less force in the weaker limb during all force matching levels. These articles are different in many ways but the main focal point is these are only two of the many ways force production can be measured. The articles demonstrate decreasing force production in the lower leg whether it is between cryotherapy treatments or dominant versus non dominant leg strength. Agility Agility is defined as the ability to change direction rapidly and also to change that direction accurately.34-38 Agility is frequently compared to speed; however, speed is movement in a straight path whereas agility is multidirectional. Vescovi et al39 studied the relationships between different agility tests in female athletes. This study 35 examined 83 high school soccer, 51 college soccer and 79 college lacrosse athletes. These athletes were tested by linear sprinting, countermovement jump, and agility. Test outcomes were determined through Pearson’s correlation coefficients when pairing the testing trials. Correlation categories were low, moderate and high. The relationships in linear sprint times were strongly correlated. The relationship between countermovement jump height and linear sprinting was stronger with longer distance compared to shorter distances. The results of this study indicate linear sprinting, agility, and vertical jumping are independent locomotor skills and suggest a variety of tests ought to be included in an assessment protocol for high school and college female athletes.39 Patterson et al40 tried to determine if cold whirlpool treatment decreases functional performances equally regardless of gender. This study also looked at the time functional performance increased after cold whirlpool. Subjects were volunteers, all of college age. All subjects performed four measures of functional performance including vertical jump, t- test, 40 yard dash and active range of motion of the ankle. Subjects were treated with 20 minutes of a cold whirlpool after the pre-tests. In testing after the cold whirlpool, subjects showed significant decreases 36 in all four measures of performance immediately after treatment. After 32 minutes, vertical jump was the only test that was still decreased. In addition, subjects showed decreased levels of peak power and average power. These results suggest functional performance was affected immediately following and up to 32 minutes after the cold whirlpool treatment. It also shows that there is a gradual increase in functional performance over time after cryotherapy application. Agility is an important athletic attribute for any athlete to have and it can be affected by cryotherapy prior to athletic performance. Balance Balance is the body’s steady state of which the body finds its center and has a base of support.41 Balance is necessary for athletic performance. Balance is the basis for body support, postural control, center of gravity and proprioception. Surenkok et al42 assessed fifteen healthy basketball players in their sense of knee joint position and static balance after the application of a cold pack and cold spray. Subjects were tested first after a cold pack application and then a week later with a cold spray application. Joint position sense was measured with a isokinetic dynamometer and assessed by a single leg balance 37 before and after cryotherapy. Subject’s knees were tested with a continuous passive motion machine. Knee passive range of motion was flexion and extension from 0 to 90 degrees and movement at a velocity of five degrees per second. Significant differences were found in joint position sense before and after cold spray application and between joint position sense scores and pain. However, results on the single-leg balance tests showed no significant differences. Thus, joint position sense is negatively affected with cryotherapy use which will alter body balance and can adversely affect an athlete and athletic performance immediately after cryotherapy. An article by Rivers41 investigated the effects of cryotherapy on total body balance and proprioception with an Aircast bracing in 25 males and females. Subjects were tested for one minute trials and were in treatment conditions of cryotherapy and bracing or the control which was neither cryotherapy nor bracing. There was a pre-test followed by a 20 minute treatment and five, one minute balance trials. There was a significant decrease in total body balance after the first three minutes post treatment, but no significant decrease from four to ten minutes after cryotherapy treatment. There was no significant difference in balance with or without the bracing. From these two 38 articles we find that cryotherapy does have an adverse effect on whole body balance. Additionally from the article by Rivers, we know that the addition of a brace cannot compensate for the balance lost by cryotherapy. Speed Speed is commonly measured in a 40 yard sprint.34 Patterson et al40 was testing the effects of a cold whirlpool on power, speed, agility and range of motion on twenty-one subjects. For the sprint portion, subjects ran 40 yards on an indoor track surface. Prior to testing, subjects lightly jogged a lap of 200 meters for a warm up. The warm up was followed by four to six trials of submaximal level sprints for practice. No stretching was allowed. After practice a 60 second rest was given before the 40 yard sprint was completed. After the testing was completed the subject’s legs, fibular head down, were placed in a cold whirlpool for twenty minutes. Once treatment was completed the 40 yard dash was performed in intervals for 32 minutes. The mean times for the 40 yard dash were significantly increased at 2, 7, 12, and 22 minutes after the cold whirlpool compared to the pre test. There was no difference in the 17, 27, and 32 minutes after cold whirlpool immersion. Thus, cooling the body before a 39 sprint run can decrease performance regarding sprint time up to 22 minutes. Castle et al43 examined the effects of pre-cooling the body with an ice vest. The subjects were in the following conditions: 1)the upper body cooled via cold packs, 2)the thigh muscles cooled locally, 3)and the whole body immersed in a cold tub chest down; to counter act the effects of muscle fatigue when sprinting in a hot, humid condition. The hypothesis was that if the hot and humid condition was controlled with pre-cooling of muscles, the muscles would not increase their temperature as quickly which in turn would decrease the amount and quickness of cross-bridging occurring. This in turn would decrease the fatigue rate in sprinting. Twelve males completed four cycling sprints with 10 seconds of passive rest, five seconds of maximal sprint against a resistance of 7.5% their body mass, and 105 seconds of active recovery. After the sprint, subjects were either not cooled, cooled with a vest, cold ice packs or both for 20 minutes. This study showed that fatigue due to the heat occurred the quickest in the control group but was similar to the vest cooling group. The cold packs and water immersion did not have humidity effects; increased muscle temperature and decreases in peak power output occurred until 16 minutes into the exercise. Thus, this study 40 determining that pre-cooling reduced heat strain in sprint cycling. Fatigue Muscle fatigue is a limitation to athletic performance in which the muscles are no longer able to produce a sufficient amount of force to continue physical activity.44 Although fatigue is developed at a muscular level, mental processes, such as motivation and outside influences, can also affect the reduction in power output and/or fatigue.44 Muscle fatigue can be affected by long duration of specific physical activity; however, short-durations of local application of cryotherapy can lower muscle temperature and delay the onset of work fatigue.40,41 Verducci39 investigated the effects on work, velocity and power when icing the arm and shoulder between weight lifting sets. Ten males, all members of a private athletic club, participated in this study. Each subject had to pull 75% of their one repetition 22 times for each set as fast as possible. Afterward, subjects were either iced or had towels placed over their arms for three minutes and rested for 4.5 minutes. The testing continued in this fashion until 22 pulls could not be completed without stopping. Work was measured by the number of arm pull sets completed 41 before fatiguing, velocity was measured by the time it took to complete each set, and power was determined by dividing work by velocity. Cryotherapy between sets resulted in having a significant effect on the number of arm pull sets, how fast the sets were completed and how much power was produced during the set. Thus, interval cryotherapy decreases fatigue rate and increases work, velocity and power. Crowley et al44 used the Wingate anaerobic power test to examine if peripheral hypothermia caused an impairment in peak power and anaerobic performance before and after testing. Three males participated in this study, with a warm up on the bike prior to the subjects being tested on the Wingate test. After testing, subjects were treated with a no cooling process or a leg cooling from the waist down in an ice bath. After this, another Wingate test was taken and then a re-warming bath took place until skin and rectal temperatures returned to normal. This study found that peak power, average power output and point of fatigue were decreased with cooling. Although this is a great test to illustrate a fatiguing process, this study is limited in the use of only three subjects. For a short term power output in the major limb muscles, the temperature required appears to be slightly 42 higher than that found in resting muscle in a thermoneutral environment.43 Higher temperatures resulted in a significantly faster onset of work fatigue44-46, while mildly cold applications resulted in significantly longer work periods.46,47 Summary Cryotherapy is the most commonly used modality in athletics today.1-3 Cryotherapy is used in the beginning phases of acute injury treatment and many studies have shown that cryotherapy reduces metabolism, inflammation, and muscle spasms as well as controlling pain.4-9 All studies that were looked at showed negative effects on performance but none looked at the effect of cryotherapy on fatigue rate. Therefore more research needs to be done in the field to obtain a conclusive result of how cryotherapy affects performance in all aspects. The findings could eventually impact the player’s ability to return to play after injury and the Athletic Trainer’s decision to apply cryotherapy during and before play. 43 APPENDIX B The Problem 44 THE PROBLEM Statement of the Problem Cryotherapy is the most commonly used therapeutic and rehabilitative treatment when an acute injury is present.1 Specifically, cryotherapy is used when pain, inflammation, metabolism and swelling need to be decreased. Through education, cryotherapy is taught to be used after activity due to its diminishing effects on the vasculature and musculature which can decrease athletic performance. Athletic performance is a combination of agility, balance, force production, speed and the body’s ability to decrease the fatigue rate.2 Without these components athletic performance could be impaired. Furthermore, many athletes use cryotherapy before athletic performance in order to play without pain. However, it is unclear if cryotherapy can decrease athletic performance enough to cause an injury. Unfortunately, after activity is not the only time cryotherapy is used. Cryotherapy can be seen in use before and during activity. The purpose of this study is to examine the effects of cryotherapy on peak landing force on single-leg vertical jumps. There have been many conflicting studies reporting differing effects of this modality on peak landing forces. 45 Most research has found that cryotherapy decreases peak landing force immediately after cryotherapy treatment with diminishing effects as re-warming occurs. This information is important to know, if there is a limiting effect on peak landing force after cryotherapy than there is a decrease in performance. This may change the usage patterns of this modality immediate before participation. Definition of Terms The following definitions of terms will be defined for this study: 1) Cryotherapy- the application of a cold modality, specifically for this study it will include ice immersion and ice bags. 2) Single-leg Vertical Jump- is the maximal height at which an individual can jump straight up and land on the dominant leg. 3) Peak Landing Force- the greatest amount of force that is produced during the landing portion of the singleleg vertical jump. 4) Re-warming- the tissue reaction after a cryotherapy modality is removed, blood flow increases to the area and the tissues begin to re-warm, maybe increased by activity. 46 5) Physically active- participating in moderate to intense exercise at least 3 times per week. Basic Assumptions The following are basic assumptions of this study: 1) The previous subjects honestly completed the demographic sheet. 2) The previous subjects understood the instructions given to them during the study. 3) Subjects performed to the best of their ability. 4) The data that was collected was collected accurately. 5) The data that was collected was utilized accurately. Limitations of the Study The following are possible limitations of the study: 1) The subjects are volunteers and are limited to physically active subjects from California University of Pennsylvania. 2) Testing done with previously collected data. Significance of the Study This study is relevant because many Athletic Trainers prescribe cryotherapy for their athletes before participating in sporting events. Frequently cryotherapy treatment can be indicated at half time if an injury 47 occurred during the game. For these Athletic Trainers, knowing whether cryotherapy causes a diminishing effect on peak landing force may have professionals re-evaluate the application of cryotherapy before or during physical performance. If cryotherapy has an effect on physical performance then it should be known that a sufficient warm up is needed after the removal of cryotherapy before returning the athlete to play. If it is found that cryotherapy does not have any effect on physical performance then professionals can know that it is safe to put an athlete back to play after using cryotherapy. 48 APPENDIX C Additional Methods 49 APPENDIX C1 Institutional Review Board – California University of Pennsylvania 50 Institutional Review Board California University of Pennsylvania Psychology Department LRC, Room 310 250 University Avenue California, PA 15419 instreviewboard@calu.edu Robert Skwarecki, Ph.D., CCC-SLP,Chair Ms. Wilson, Please consider this email as official notification that your proposal titled “The Efects of Cryotherapy on Landing Forces During a Single Leg Jump” (proposal # 10066), described as re-analysis of existing anonymous data from a previous CalU IRB approved study (proposal #09-037: "The Effect of Cryotherapy on the Single Leg Vertical Jump") has been approved by the California University of Pennsylvania Institutional Review Board with the following stipulations: -Only currently existing data (as of 03-28-11) from study #09-037 (listed above) may be used. No additional data may be collected from new or prior participants. -Data must be provided to you stripped of any identifiers that can be linked to participant identity. -Communication with the researchers from study #09-037 (if any) must be conducted in a manner that does not reveal participant identity/identifiers to you. The effective date of the approval is 03-28, 2011 and the expiration date is 03-27-2012. These dates must appear on the consent form. Please note that Federal Policy requires that you notify the IRB promptly regarding any of the following: (1) Any additions or changes in procedures you might wish for your study (additions or changes must be approved by the IRB before they are implemented) (2) Any events that affect the safety or well-being of subjects (3) Any modifications of your study or other responses that are necessitated by any events reported in (2). (4) To continue your research beyond the approval expiration date of 03-22-2012 you must file additional information to be considered for continuing review. Please contact instreviewboard@calu.edu 51 Please notify the Board when data collection is complete. Regards, Robert Skwarecki, Ph.D., CCC-SLP Chair, Institutional Review Board 52 53 54 55 56 57 58 59 60 61 62 63 APPENDIX C2 Excel Spreadsheet Data Collection 64 Table 3: Mean Peak Landing Forces: The Cryotherapy Group Subject Pretest Posttest 5 min 10 min 20 min 1 1302.678 1454.809 1073.738 1588.884 2145.062 2 2603.1218 1804.31 1585.893 1759.621 2542.827 3 2574.8536 2520.11 2610.605 2425.146 2740.54 5 3284.3458 3090.873 3191.118 3412.208 2449.415 6 2784.111 2479.68 2853.577 2250.278 1559.135 7 4933.6224 3959.965 5023.578 3382.363 3963.336 8 1943.2996 1838.223 1905.264 2237.103 2077.899 10 4989.9684 5311.623 2911.031 5705.027 5205.072 12 4685.1774 3028.782 3499.896 3742.943 3651.279 13 3086.3194 2476.876 2954.488 2350.63 2519.33 14 2089.293 2420.022 2420.827 2396.807 2126.353 15 2667.9722 3098.05 3076.823 2797.518 2608.149 Table 4: Mean Peak Landing Forces: The Control Group Subject Pretest Posttest 5 min 10 min 20 min 1 1180.341 1239.555 1382.559 1555.728 1376.923 2 2106.846 2083.754 2189.751 2333.313 2061.389 3 2489.037 2283.597 2413.615 2328.705 2355.53 5 3945.647 2853.889 3118.37 2523.796 3103.627 6 2869.606 2751.731 2446.73 2394.76 2042.223 7 3909.152 4181.195 4315.261 4316.937 3976.185 8 2734.954 2778.525 2564.019 2724.899 2650.604 10 4352.129 4771.087 5372.709 4423.073 4419.162 12 3641.019 3157.263 3710.811 3565.172 3762.762 13 2400.112 2193.867 2371.304 2000.594 2280.655 14 2532.923 3224.296 4023.108 3117.043 4202.422 15 2749.99 2604.798 2066.298 2762.884 2813.159 65 EXAMPLE OF BIOANALYSIS GRAPH: A SINGLE-LEG VERTICAL JUMP 66 REFERENCES 1. Merrick MA, Knight KL, Ingersol CD, Potteiger JA. The effects of ice and compression wraps on intramuscular temperatures at various depths. J Athl Train. 1996; 28 (3):236-245. 2. Richendoller ML, Darby LA, Brown TM. Ice bag application, active warmup and three measures of maximal functional performance. J Athl Train. 2006; 41(4):364-370. 3. Evans T.A, Ingersoll C, Knight K.L, Worrell T. Agility following the application of cold therapy. J Athl Train. 1995; 30(3):231-234. 4. Merrick MA. Secondary injury after musculoskeletal trauma; a review and update. J Athl Train. 2002;37:209-217. 5. Merrick MA, Rankin JM, Anders FA, Hinman CL. A preliminary examination of cryotherapy and secondary injury in skeletal muscle. Med Sci Sports Exerc. 1999;31:1516-1521. 6. Knight KL. The effects of hypothermia on inflammation and swelling. Athl Train J Natl Athl Train Assoc. 1976;11:7-10. 7. Knight KL. Cryotherapy in sports injury management. Champaing, IL: Human Kindetics; 1995. 8. McGown HL. Effects of cold application on maximal isometric contraction. Phys Ther. 1967;47:185-192. 9. Krause B. Neurological Responses to Cold. Athletic Training Today. 2003; 8(4):59-61. 10. Hubbard T.J, Denegar C.R. Does cryotherapy improve outcomes with soft tissue injury? J Athl Train. 2004; 39(3):278-279. 67 11. Bleakley C, McDunough S, MacAuley P. The use of ice in the treatment of acute soft tissue injury; a systemic review of randomized controlled trials. Am J Sport Med. 2004; 32:251-261. 12. Peiffer J.J, Abbiss C.R, Nosaka K, Peake J.M, Larsen P.B. Effect of cold water immersion after exercise in the heat on muscle function, body temperatures, and vessel diameter. J Sports Sci Med. 2009; 12(1): 91-96. 13. Dykstra J, Hill H, Miller M. Comparison of cubed ice, crushed ice, and wetted ice on intramuscular and surface temperature changes. J Athl Train. 2009; 44(2):136-141. 14. Merrick Ma, Jute LS, Smith ME. Cold modalities with different thermodynamics properties produce different surface and intramuscular temperature. J Athl Train. 2003;38(1): 28-33. 15. Kanlayanaphotporn R, Janwantanakul P. Comparison of skin temepertures during the application of various cryotherapy modalities. Arch Phys Mod Rehabil. 2005;86(7):1411-1415. 16. Kennet J, Hardaker N, Hobbs S, Selfe J. Cooling efficiency of four common cryotheraptic agents. J Athl Train. 2007;42:343-348. 17. Hlgafly AA, George KP. The effect of cryotherapy on nerve conduction velocity, pain threshold and pain tolerance. Br J Sports Med. 2007;44:356-369. 18. Chesterton LS, Foster NE, Ross L. Skin temperature response to cryotherapy. Arch Phys Med Rehabl. 2002;83:543-549. 19. Starkey C. Therapeutic Modalities. Philadelphia, Pa. FA Davis; 1991. 20. Michalski WJ, Seguin JJ. The effects of muscle cooling and stretch on muscle spindle secondary endings in the cat. J Physiol. 1975;253:341-356. 21. Carrasco MA, Conzales JM. Conductive cooling of the forehead during physical activity increases comfort 68 and dampens the magnitude of physiological response. JEP. 2009;12(2):9-10. 22. Enwemeka C, Allen C, Avila R, Bina J, Konrade J, Munns S. Soft tissue thermodynamics before during and after cold pack therapy. Med & Science Sports & Exercise. 2002;34:45-50. 23. Prentice W. Therapeutic Modalities in Sports Medicine. 2nd ed. St. Louis, MO: Mosby; 1990. 24. Rubley M. D, Denegar C.R, Buckley W.E, Newell K.M. Cryotherapy, Sensation, and Isometric-force variability. J Athl Train. 2003; 38(2):113-119. 25. Coppin EG, Livingstone SD, Kuenn LA. Effects on handgrip strength due to arm immersion in a 10 degree C water bath. Aviat Space Environ Med. 1978;49:13221326. 26. Kowal MA. Review of physiological effects of cryotherapy. J Orthop Sports Phys Ther. 1983;5:66-73. 27. McMaster WC. Cryotherapy. Phys Sports Med. Nov 1982; 10:112-119. 28. McMaster WC. A literay review on ice therapy in injury. Am J Sport Med. 1977;2:124-126. 29. Cross KM, Wilson RW, Perrin DH. Functional Peformance following an ice immersion to the lower extremity. J Athl Train. 1996;31(2):113-116. 30. Simon AM, Ferris DP. Lower limb force production and bilateral force asymmetries are based on sense of effort. Exp Brain Res. 2008;187:129-138. 31. Gross TS, Nelson RC. The shock attenuation role of the ankle during landing from vertical jump. Med Sci Sports Exerc. 1998;20(5):506-514. 32. Prapavessis H, McNair PJ. Effects of instruction in jumping technique and experience jumping on ground reaction forces. J Orthop Sports Phys Ther. 1999;29(6):352-356. 69 33. Jameson A, Kinzey S, Hallam J. Lower-extremity-joint cryotherapy does not affect vertical ground reaction force during landing. J Sport Rehabil. 2001;10:132142. 34. Bloomfield J, Ackland TR, Elliot BC. Applied anatomy and biomechanics in sports. 1996; Melbourne, VIC: Blackwell Scientific. 35. Clark HE. Application of measurements to health and physical education. 1959. Englewood Cliffs, NJ: Prentice-Hall. 36. Matthews DK. Measurements in physical education. 1973. Philadelphia, PA: W.B Sanders. 37. Barrow H, McGee R. A practical approach to measurement in physical education. 1971. Philadelphia, PA: Lea and Febiger. 38. Johnson BL, Nelson JK. Practical measurements for evaluation in physical education. 1969. Minneapolis, MN: Burges. 39. Vescovi J, McGuigan M. Relationships between sprinting, agility, and jump ability in female athletes. J Sport Sci. 2008: 26:97-107. 40. Patterson S, Uderman B, Doberstein S, Reineke D. The effects of cold whirlpool on power, speed, agility and range of motion. J Sport Sci Med. 2008;7:387-389. 41. Rivers D.A. The influence of cryotherapy and Aircast bracing on total body balance and proprioception. J. Athl Train. Microform Publications, Int'l Institute for Sport and Human Performance, University of Oregon. 1995. 42. Surkok O, Ayter A, Tuzun EH, Akman MN. Cryotherapy impairs knee joint position sense and balance. Iso & Exer Sci. 2008;16(1):69-73. 43. Castle P, Macdonald A, Philp A, Webborn A, Watt P, Maxwell NS. Precooling leg muscles improves sprint exercise performance in hot, humid conditions. J Appl Phys. 2006;100(4):1377-1385. 70 44. Crowley GC, Garg A, Lohn MS, VanSomeren N, Wade AJ. Effects of cooling the legs on performance in astrandard wingate anerobic power test. Br J Sport Med. 1991;25(4):200-203. 45. Benjaminse A, Habu A, Sell TC, Abt JP, Fu FH, Myers JB, Lephart SM. Fatigue alters lower extremity kinematics during a single-leg stop-jump task. Sports Traumatology. 2008;16(4):400-408. 46. Tinazci C, Acikada C. Reproducibility and validity of hacettepe intermittent jumping test. Iso & Exer Sci. 2009; 17(2):93-99. 47. Orishimo KF, Kremenic JJ. Effect of fatigue on singleleg hop landing biomechanics. J Appl Biomech. 2006;22(4):245-254. 48. Denegar, CR, Saliba E, Salibe S. Therapuetic Modalities for Musculoskelatal Injuries Second Edition 2006; Human Kinetics. 71 ABSTRACT TITLE: THE EFFECT OF CRYOTHERAPY ON LANDING FORCES DURING A SINGLE LEG JUMP RESEARCHER: Danielle Wilson ADVISOR: Dr. Thomas F. West RESEARCH TYPE: Master’s Thesis OBJECTIVE: The purpose of the study is to examine the effects of cryotherapy on the lower extremity and peak landing forces measured during a single-leg vertical jump. DESIGN: Quasi-experimental, within subjects, repeated measures design. PARTICIPANTS: Twelve physically active college age students who volunteered with no previous injuries or cold contraindications. MAIN OUTCOME MEASURES: Peak landing force, treatment (cryotherapy and no cryotherapy), and time (pretest, posttest, five minutes, ten minutes, twenty minutes after posttest). RESULTS: The results showed there was no significant difference with cryotherapy treatments on peak landing forces or time. The results also showed that there was no significant difference with the interaction of cryotherapy and time. CONCLUSIONS: The results being insignificant, suggests that it is safe to have an athlete return to play immediately after cryotherapy treatment. However, it is recommended through other studies that a warm-up should be performed before the athlete returns to play. WORD COUNT: 175