A COMPARISON OF KNEE INJURIES AMONG MEN AND WOMEN VOLLEYBALL PLAYERS IN HONG KONG YU NOK TING (DR. ROSETTA, MUI)

Transcription

1 A COMPARISON OF KNEE INJURIES AMONG MEN AND WOMEN VOLLEYBALL PLAYERS IN HONG KONG YU NOK TING (DR. ROSETTA, MUI) 25 th April,2016

2 HONG KONG BAPTIST UNIVERSITY LIBRARY Honours Project Release Form Thesis Title: A Comparison of Knee Injuries Among Men and Women Volleyball Players in Hong Kong Author: Yu Nok Ting Student No.: Department: Physical Education Programme: Bachelor of Social Science in Sports and Recreation Leadership Declaration: I agree that the full text of my thesis may be consulted by the HKBU community users in print version in the Hong Kong Baptist University Library according to the circulation regulations currently in force. All Rights are reserved and governed by the Hong Kong Copyright Ordinance. Signature of Author: Date: 25th April, 2016

3 HONG KONG BAPTIST UNIVESITY 25 th APRIL, 2016 We hereby recommend that the Independent Project by Ms. Yu Nok Ting entitled A COMPARISON OF KNEE INJURIES AMONG MEN AND WOMEN VOLLEYBALL PLAYERS IN HONG KONG be accepted in partial fulfillment of the requirement for the Bachelor of Social Science in Sports and Recreation Leadership. DR. ROSETTA, MUI Chief Advisor

4 DECLARATION I hereby declare that this honours project A COMPARISON OF KNEE INJURIES AMONG MEN AND WOMEN VOLLEYBALL PLAYERS IN HONG KONG represents my own work and had not been previously submitted to this or other institution for a degree, diploma or other qualification. Citations from the other authors were listed in the references. Yu Nok Ting 25 th APRIL,2016

5 ACKNOWLEDGEMENTS I would like to express my deepest gratitude to my supervisor, Dr Rosetta, Mui for guiding and supporting me throughout the entire study. Last but not the least, I would like to thank the participants and the coachers. My project would have not been conducted smoothly without their participation and supports. Yu Nok Ting Department of Physical Education Hong Kong Baptist University Date: 25 th APRIL,2016

6 ABSTRACT AIMS: This cross-sectional study aimed to examine the incidence rate and risk factors among a sample of men and women volleyball player in Hong Kong. METHODS: Members form university volleyball team, volleyball club of Division I and Hong Kong volleyball team were invited to participate into this study. Participants reported on the habit of volleyball training and knee injuries suffered within the past one year. IBM SPSS statistics 21 was used for data analysis. Chi-square test was performed to test between group differences of categorical variables. RESULTS: A total of 142 players aged years (70 men, 72 women) were invited and all of them participated into the study, with a participation rate of 100.0%. The overall incidence rate of knee injures within the past one year was 62.7%. Most of the knee injuries were minor (i.e. overuse injury). Women were more likely to suffer from ACL tear injury than their counterparts. (73.7% vs 26.3%, p=0.031). There was significance difference in the amount of time for fitness training and weight training between injured and non-injured players (p=0.002; p=0.005). CONCLUSIONS: Most of the injured players suffered from overuse injury. It

7 was hard to prevent due to the sport nature of volleyball. The amount of time spent in fitness and weight training is significance factor to reduce the risk of getting knee injuries. Future research in a large-scaled sample should be conducted to confirm the findings. In addition, preventive measures should be implement to prevent and reduce the incidence rate of knee injuries among Hong Kong volleyball players. Keywords: Knee injuries; volleyball players; Hong Kong

8 TABLE OF CONTENTS CHAPTER Page 1. INTRODUCTION 1 Statement of Problem.3 Study Aims and Objectives 4 Hypothesis LITERATURE REVIEW Knee Injuries in Volleyball.6 Gender difference in the knee injuries in volleyball..8 Anterior cruciate ligament (ACL) injuries in volleyball...9 Summary METHODS. 14 Subject and Sampling...14 Measurements...14 Data Collection Procedures..15 Data Analysis...16 Timeline of the Project RESULTS Demographic Information Knee Injuries in Different Genders Regular Training of Injured Players and Non-Injured Players...24 Fitness Training of Injured Players and Non-Injured Players.. 27 Weight Training of Injured Players and Non-Injured Players..29

9 Warm Up and Cool Down Patterns of Players Categories of Knee Injuries Types of Knee Injuries Suffered by Players Antecedents of Knee Injuries Treatment for Knee Injuries Rehabilitation of Knee Injuries DISCUSSION AND CONCLUSIONS..43 Knee Injuries of Men and Women Volleyball Players.43 Fitness Training and Weight Training..44 Warm Up and Cool Down Patterns of the Players...45 Patterns of Knee Injuries of the Players...46 Antecedents of Knee Injuries...47 Treatments of Knee Injuries.49 Recovery Time..50 Prevention of Knee Injuries..50 Summary of Results..52 Conclusion...56 Recommendations for Future Studies...57 REFERENCES. 59 APPENDICES.. 63 Questionnaire 63

10 LIST OF TABLES AND FIGURES TABLE Page 1. Frequency and Percentage of Players Demographic Information Knee Injuries in Different Genders Regular Training/Competition of Injured Players and Non-Injured Players Fitness Training of Injured Players and Non-Injured Players Weight Training of Injured Players and Non-Injured Players Warm Up Activities of Injured Players and Non-Injured Players Cool Down Habit of Injured Players and Non-Injured Players Categories of Knee Injuries of Injured Players Types of Knee Injuries Suffered by Players The Rate of ACL Tear Injury among Genders Antecedents of Knee Injuries Treatment for Knee Injuries Number of Knee Injuries requiring Surgery Amount of Time for Recovery of Injured Players..42 FIGURE 1. Knee Injuries in Different Genders Regular Training/Competition of Injured Players and Non-Injured Players Fitness training of Injured Players and Non-Injured Players Weight Training of Injured Players and Non-Injured Players Warm Up Activities of Injured Players and Non-Injured Players Cool Down Habit of Injured Players and Non-Injured Players.. 35

11 1 Chapter 1 INTRODUCTION Volleyball is one of the most popular sports all over the world. In Hong Kong, it is increasingly popular due to the promotion of Volleyball Association of Hong Kong, china (VBAHK). Every year, the FIVB Volleyball World Grand Prix- Hong Kong (WGP-HK) is hold in Hong Kong Coliseum with full house audience. All matches are broadcast live or delayed by local and international. TV media with high audience rating (Major Sports Events Committee, 2009). Through WGP-HK and various promotional activities, it is significant in popularizing volleyball. Volleyball is unique among different team sports as it evolved into two distinct disciplines: indoor game that consists of six players in each team, and outdoor game that consists of two players per side. It will focus on indoor volleyball in this study. Moreover, volleyball is moderate level of activity that associated with numerous health benefits, including improved. physical fitness, weight control, increased muscle strength etc. (The department of health, 2011). According to the world health organization (2015), it recommends that children and youths aged 5-17 to accumulate at least 60 minutes of moderate- to vigorous-intensity physical activities

12 2 daily. In addition, volleyball is a kind of team sports, players could learn how to communicate and cooperate with others when they are participating in volleyball games. As a result, Hong Kong physical education teacher would include volleyball teaching in the syllabus. Apart from volleyball lesson in schools, there are different levels of volleyball competition in Hong Kong. For instance, inter- secondary school sports competition organized by Hong Kong Schools Sports Federation, inter-university sports competition organized by University Sports Federation of Hong Kong, China and the Hong Kong Open Volleyball Championship Competition organized by Volleyball Association of Hong Kong, China. Volleyball players need to engage in regular training and fitness training to prepare for the competition. The heavy physically demanding sports including volleyball, seems. to have an increased risk for developing patellar tendinopathy (Van Der Worp, Frings-sen, Van Den Akker-Scheek, Zwerver & Kuijer, 2011). Among the different levels of volleyball competition, inter-university competition and HK open volleyball championship competition in division I would be the most physically demanding. Compare with other team contact sports such as

13 3 soccer, basketball, ice hockey, the overall. injury risk was lowest in volleyball. However, injury in volleyball cannot be neglect. Most injuries happen to the lower limbs in volleyball. Knee is the most common location for injuries resulting in permanent. disability (Kujala, Taimela, Antti-Poika, Orava, Tuominen, & Myllynen, 1995). Also, some reference suggest that waist girth may have a biochemical as well as a mechanical influence on the development of patellar tendon pathology which lead to increased risk of knee injury among women volleyball players. Normally, it would take injured players around 1-2 weeks to return to play. If they suffer from knee.dislocation, they would return to their previous sport after a median time of 5.5 months, with some of them could. return to pre-injury levels (Hirschman, Iranpour, Mulle, & Friederich, 2010). It depends on the severity of knee injury. To reduce the injury rate of knee injury among volleyball player, we should identify the risk factors and suggest a prevention plan. Statement of Problem This study would focus on the comparison of the rate and types of knee injuries between men and women volleyball team. members in Hong Kong. It also aimed at examine the relationship between the gender and patterns of knee injuries.

14 4 Study Aims and Objectives This study would aim to compare knee injuries among men and women volleyball players in Hong Kong. This study would provide preliminary information about knee injuries pattern among a sample of men and women volleyball player in Hong Kong. In addition, the study would also examine the relationship between various risk factors and incidence rate of knee injury.

15 5 Hypothesis The following are the research hypothesis of this study: 1. There would be no significance difference in the rate of knee injuries between men and women volleyball players in Hong Kong. 2. There would be no no significant difference in volleyball training frequency between injured and non-injured players. 3. There would be no significant difference in fitness training frequency between injured and non-injured players. 4. There would be no no significant difference in weight training frequency between injured and non-injured players. 5. There would be no significance difference in the rate of ACL tear injury between men and women volleyball players.

16 6 Chapter 2 REVIEW OF LITERATURE Some existing literature present the situation of knee injury in volleyball. This review of literature divided into four sections: (i) knee injuries in volleyball, (ii) gender difference in the knee injuries in volleyball, (iii) anterior cruciate ligament (ACL) injuries in volleyball, and (iv) summary. Knee Injuries in Volleyball According to James, Kelly & Beckman (2014), Volleyball is recognized as one of the most popular sports in the world amongst men and women. It explains that why there are more and more people participate in both indoor and outdoor volleyball activities. Through participation in volleyball, the participants could get numerous health benefits. For instance, increased in muscle strength, improved cardiovascular endurance, coordination and balance (The department of health, 2011), but there are risks of getting injured due to sport-specific tasks, such as landing and jumping. Bere, Kruczynski, Veintimilla, Hamu, Bahr (2015) conduct a study on the risk and pattern of injuries among world-class players. According to the result, most commonly injuries of volleyball players were to the lower extremity (58.3%), with

17 7 15.2% of those injuries affecting the knee. This distribution was similar between match play (15.6%) and training (13.2%). The National Collegiate Athletic Association (NCAA) (Agel, Palmieri-Smith, Dick, Wojtys & Marshall, 2007) suggested that the lower extremity accounted for more than 55% of all game and practice injuries. It found that the rate of injury in competition was slightly higher than in practice in national level which is similar to international level. Another study conducted by Kujala et al. (1995) reveal that 19.0% of the volleyball injuries occurred in the knee. Throughout the 32 International Volleyball Federation (FIVB) events included, there were 440 injuries reported. The most common injury type was joint sprains (32.5), followed by muscle strains (14.1%) and contusions (12.7%) (Bere, 2015). An injury that result in at least 10 consecutive days of restricted or total loss of participation is classified as severe injury. Therefore, the most common injury type was ligament sprain (29.1%) and followed by internal derangement (25.7%) in NCAA volleyball competition (Agel etal. 2007). And Kujala et al. (1995) shows that the common injury type was knee sprains and muscle stains (15.4%) for Finland volleyball players.

18 8 For the cause of injury, there are 23% were reported as the result of contact between players, followed by 20.7% were overuse injuries, and 17.3% were reported as non-contact trauma. The knee injuries mainly affected by overuse problem (Bere, 2015). Refer to Agel, J. (2007), most injuries (>50%) did not involve direct external contact to the injured body part. The percentage of injuries in player contact, other contact (e.g. balls, floor) and no contact were similar during games; however the result of injuries in practice was no contact (54.0%), followed by other contact (27.0%) and player contact (15.0%). According to Reeser, (2006), Patellar tendinitis is an overuse injury. Symptom onset typically occurs gradually after a threshold of cumulative tissue injury has been exceeded. Therefore, players who increase the dynamic load on the patellar tendon would increase the risk of developing anterior knee pain (jumper s knee). (Reeser, Verhagen, Briner, Askeland, & Bahr, 2006) Patellar tendinitis, also known as jumper's knee, is probably so common in volleyball because of the high frequency of jumping in the sport (Briner Jr, & Kacmar, 1997). Gender difference in the knee injuries in volleyball There is no significant difference between males and females in the international volleyball competition (Bere, 2015). However, gender difference in peak torque

19 9 suggest that strength may influence the higher knee injury incidence in female athletes (Bowerman, Smith, Carlson & King, 2006). The presence of a Hamstring: quadriceps (H: Q) strength ratio below normal range (<60% at 60 /s and <80% at 300 /s) was linked to an increased incidence of overuse knee injuries among female collegiate athletes. Male collegiate athletes produced more peak torque, work, and average power compared to their female counterparts (Anderson, Dome, Gautam, Awh, & Rennirt, 2001; Huston & Wojtys, 1996). Males also demonstrated significantly higher (p<0:04) H: Q strength ratios at 601/s compared to females (Anderson et al. 2001). Several studies have revealed that muscular strength deficits and low H: Q ratios were linked to injury. To reduce the risk of knee injuries and maintain normal knee function, a balance between the quadriceps and hamstring muscles is important. Women in general are more flexible, with looser ligaments, tendons and muscles, which increase the risk of knee injury (Nora. & Aartan, 2015) Therefore, the strength deficit may be a possible risk factor to explain the higher knee injury incidence in female athletes compared to male. Anterior cruciate ligament (ACL) injuries in volleyball Although it is less common among volleyball player, anterior cruciate ligament

20 10 (ACL) injuries can be particularly devastating to an athlete. The ACL injuries frequently occur in minimal contact or non-contact situation. The actions of cutting manoeuvres, landing from a jump, sudden deceleration were the high risk mechanisms for ACL injuries. The leading cause of ACL injuries amongst volleyball players are via non-contact mechanisms such as landing, jumping. Therefore, middle, left and right hitters are at high risk of ACL injury as they have to perform these actions repeatedly during practice and competition. (Agel et al. 2007& Ferretti, 1992). From the result of Agel et al. (2007), only 5% of all volleyball injuries were acute knee injuries, while 3.7 % of injuries were to the ACL. de Loës, Dahlstedt, and Thomée (2000) reported the incidence of ACL rupture as two injured athletes per 100,000 athletes during 1 hour in male volleyball. However, an extended rehabilitation period exists for ACL injury, represented by an 11-month return-to-play duration, in addition to potentially permanent disability (Ferretti, Papandrea, Conteduca, & Mariani, 1992). According to Hughes, Watkins, & Owen, (2010), the normalized knee varus moment exhibited by males was significantly different from the normalized knee valgus moment exhibited by females during active loading, and the maximum

21 11 normalized knee valgus moment was significantly greater in females than males. This could cause overloading of knee muscles and contribute to the greater incidence of non-contact ACL injuries in females than their counterparts (Hughes, Watkins, & Owen, 2010). Also, Zahradnik, (2015) showed that the step-back technique (after unsuccessful block) resulted in a greater vertical ground reaction force, reduced knee energy absorption and increase hip energy absorption than the stick technique (after successful block). (Zahradnik, Jandacka, Uchytil, Farana, & Hamill, 2015) The result is supported by the study that investigate the the relationships between energy absorption and prospectively identified biomechanical factors associated with non-contact anterior cruciate ligament injury. Norcross et al. (2010) reported that greater energy absorption by the hip and ankle, and less by the knee, was associated with an increased risk of ACL injury. When determining ACL loading, the degree of knee flexion is critical. If the knee flexion angle is between 0-30 O, ACL would be pre-disposed to injury (Norcross, Blackburn, Goerger, & Padua, 2010). Terauchi et al., (2011) also suggested that the majority of athletes indicate the knee position as being close to full extension at the time of injury. The position of the leg just before collapse in all the non-contact ACL

22 12 injuries was near the foot strike with the knee close to full extension (Terauchi, Hatayama, Yanagisawa, Saito, & Takagishi, 2011). Besides, the back steeping extremity may be exposed to a greater risk of ACL injury during step-back landing due to higher valgus moment. (Zahradnik et al. 2015) In addition, hamstring relative to quadriceps (H: Q) weakness can increase the potential for anterior tibial shear (DeMorat, Weinhold, Blackburn, Chudik, & Garrett, 2004). It may be that women are at greater risk for anterior cruciate ligament injury in volleyball, possibly because of their greater incidence of knee recurvatum. (Briner Jr, & Kacmar, 1997) Therefore, female volleyball players may have a greater incidence of ACL injury compare to their male counterparts. Identifying and understanding the biomechanical risk factors would help to avoid and reduce the ACL injury rates. Summary Volleyball is an increasingly popular sport all over the world. It is different from other contact sport such as soccer, basketball, injuries are resulted from non-contact mechanism and overuse of muscle. Volleyball players are required to have good

23 13 muscular strength and modify in landing techniques to avoid repeatedly overloading the muscle. The most common body site susceptible to injuries is knee in volleyball during both practice session and competition. Players are sustained by different types of knee injuries, including knee sprain, muscle stain, ligament tear and laceration. Female players in volleyball would at a higher risk in sustaining knee injuries, including ACL injury. It might due to intrinsic factors, such as hamstring: quadriceps ratio, muscle strength. Fortunately, knee injuries could be prevented by some preventive measure. For instance, modification in lower-extremity landing techniques, hamstring specific resistance training program, muscle strengthening program etc.

24 14 Chapter 3 METHODS The study was a cross-sectional study. The method of this study was divided into the following sections, including (i)subject and sampling, (ii)measurement, (iii)data collection procedure, (iv)data analysis and (v)timeline of the project. Subject and Sampling The subjects were both male and female volleyball players. The subjects were members of university volleyball team in Hong Kong in the academic year of 2013/2014 to 2014/2015, who had been participating in regular training in volleyball provided by the university team. The subjects also from the volleyball club whom had been consecutively participated in the HK open volleyball championship competition division I in the year of 2013/2014 to 2014/2015. The subjects who represented Hong Kong volleyball team or Hong Kong junior volleyball team in the year of 2013/2014 to 2014/2015 were involved. Measurements A self-reported written questionnaire has been developed to collect information of the participants. The procedure of developing this questionnaire was based on

25 15 reviewing the literature that related to the research topic. It is also modified based on honours project from HKBU honours project database (Hei, L,2012). This questionnaire was consisting of three parts. In the first part, there were mainly demographic questions. For instance, age, gender, height and weight. In the second part, it was focus on the habit in volleyball training. It included the categories of volleyball team that engaged in the past two years, player s position, the average number of training hours spent on volleyball per week, the amount of time spent on fitness training and weight training and the habit of warm up and cool down exercise. In the third part, it was focus on the knee injury occurred during volleyball training or competition within past 12 months. The background information such as the categories of knee injury, the types of knee injuries, the cause/occasion when knee injuries occurred, the types of medical treatment, the amount of time for recovery were included. Data Collection Procedure A pilot study was conducted to access the understandability and suitability of the questionnaire before distributing the self-designed questionnaire to participants. Some

26 16 of the members from Hong Kong Baptist University men and women volleyball team were asked to complete the questionnaire. After that, they were asked if the questionnaire is understandable and stated out the problem when filling up the questionnaire. The questionnaires were distributed to participants directly by the coaches. The purpose of study and instructions of filling up the questionnaire were explained to participants clearly by the coach. The participants submitted their completed questionnaire back to the coach. All complete questionnaires were gathered by the coach and returned back to researcher. Data Analysis All the data collected were inputted into the Statistical Package for Social Science 21.0 for Windows (SPSS 21.0), and being analyzed. The level of significance was set at 0.05 for all statistical analyses. Descriptive statistics, such as mean, percentage, frequency and standard deviation, were used to describe the demographic information of the participants, for example the amount of time spent in weight training, the categories of knee injury. To

27 17 determine if there was any significance difference in the rate of knee injury between genders, the amount of time of regular training, fitness training and weight training between injured and non-injured players, the chi square tests were used. Timeline of the project The project was conducted following the below timeline (Table 1): Table 1 Timeline of the project Before the time Completion of task Week 1, 2 nd semester Data collection Week 6, 2 nd semester Data analysis Week 6, 2 nd semester Writing up results Week 7, 2 nd semester Writing up discussion and conclusions

28 18 Chapter 4 RESULTS The purpose of this study was to investigate the rate and type of knee injuries among men and women volleyball players in Hong Kong. It also measured various risk factors affect the incidence rate of knee injury. The descriptive statistics, chi square test were used to analyze the data. The analyses of the data were presented in the following results: 1. Description of the demographic information, including gender, age, height and weight, types of volleyball team that players engaged in and player s position in the team. 2. Knee injuries in different genders 3. Amount of time for regular training/competition of injured players and non-injured players 4. Amount of time for fitness training of injured players and non-injured players 5. Amount of time for weight training of injured players and non-injured players 6. Warm up and cool down patterns of players 7. Categories of knee injuries

29 19 8. Types of knee injuries suffered by players 9. Antecedents of knee injuries 10. Treatment for knee injuries 11. Rehabilitation of knee injuries

30 20 1. Demographic information The modified questionnaire obtained personal information of men and women volleyball player in Hong Kong. A total of 142 volleyball players were invited to respond to the questionnaires. There were 49.3% of the players (n=70) were men and 50.7% of the the players (n=72) were women. The age of the players was % (n=11) aged 20 or below, most of 79.6% (n=113) the volleyball players aged between and 12.7% (n=18) aged 26 or above. For the height of players, 2.8% (n=4) was m, 33.1% (n=47) were m, 39.4% (n=56) were m, 21.8% (n=31) were m and 2.8% (n=4) were m. For the weight of players, 7% (n=10) were 40-49kg, 16.2% (n=23) were 50-59kg, 45.1% (n=64) were 60-69kg, 24.6% (n=35) were 70-79kg, 6.3% (n=9) were 80-89kg and 0.7% (n=1) were 90-99kg. For types of volleyball team that players engaged in within the past two years, most of the players 93% (n=132) and 66.2% (n=94) were represent volleyball team in Division I and university volleyball team respectively, 15.5% (n=22) were represent Hong Kong volleyball team/ Junior volleyball team. For player s position, 33.8%

31 21 (n=48) were left side hitter, 23.9% (n=34) were middle blocker, 14.1% (n=20) were setter, 21.1% (n=30) were right side hitter and 7% (n=10) were libero. This result was shown in Table 1.

32 22 Table 1 Frequency and Percentage of Players Demographic Information Background Demographics Frequency Percentage (%) Gender Men Women Age 20 or below or above Height Weight Types of University Volleyball Team Volleyball Club Hong Kong Team Position Left Side Hitter Middle Blocker Setter Right Side Hitter Libero

33 23 2. Knee injuries in different genders Refer to Table 2, it shown that there were 89 of the players (62.7%) suffered different types of knee injuries during training or competition within the past one year. Among all the knee-injured players, (51.7%) (n=46) were men volleyball players and 48.3% (n=43) were women volleyball players. In order to determine if there was any significance difference in the knee injuries between genders, a chi square test was used. The result was found to be p=0.46. Therefore, there was no significant difference (p>0.05) in the knee injuries between men and women volleyball players. This result was shown in Table 2 and Figure 1. Table 2 Chi Square Test for Knee Injuries Suffered from Different Genders Sport Gender Knee Injury Volleyball Total (N=142) Men (n=70) Women (n=72) Yes No Chi Square p (65.7%) (34.3%) (59.7%) (40.3%) (62.7%) (37.3%)

34 24 Figure 1 shows the knee injuries suffered from men and women volleyball players during training or competition within the past one year 3. Amount of time for regular training/competition of Injured Players and Non-Injured Players All players engaged in training and competition regularly. It shown that 9.9% (n=14) of the players spent an average of 1to 5 hours in training or competition per week, 58.5% (n=83) of the players spent an average of 6 to 10 hours in training or competition per week, 25.4% (n=36) of the players spent an average of 11 to 15 hours in training or competition per week, and the remaining 6.3% (n=9) of the players spent an average of more than or equal to 16 hours in training or competition per week. For the players who spent an average of more than or equal to 16 hours in training or

35 25 competition, there were 33.3% (n=3) engaged in both university volleyball team, volleyball club in Division I and Hong Kong volleyball team. For injured players, there were 65.2% (n=58) of the players spent an average of less than or equal to 10 hours in training or competition and per week and 34.8% (n=31) of the players spent an average of more than or equal to 11 hours in training or competition per week. For non-injured players, there were 68.3% (n=97) of the players spent and average of less than or equal to 10 hours in training or competition per week and 31.7% (n=45) of the players spent an average of more than or equal to 11 hours in training or competition per week. In order to determine if there was any significance difference in the amount of time for regular training/competition between injured and non-injured players, a chi square test was used. The result was found to be p= Therefore, there was no significant difference (p>0.05) in the amount of time for regular training/competition between injured and non-injured players. This result was shown in Table 3 and Figure 2.

36 26 Table 3 Chi Square Test for the Amount of Time for Regular Training/Competition of Injured Players and Non-Injured Players Per Week Suffered Knee Injury or Not Regular Training/ Competition (Hours) Chi Square p Yes (n=89) (65.2%) (34.8%) No (n=53) (73.6%) (26.4%) Total (N=142) (68.3%) (31.7%) Figure 2 shows the amount of time for regular training/competition of injured players and non-injured players

37 27 4. Amount of time for fitness training of Injured Players and Non-Injured Players Fitness training is another important component to enhance player s performance. All of the players engaged in fitness training. There are 24.6% (n=35) of the players spent an average of less than or equal to 30 minutes in fitness training, 38.7% (n=55) of the players spent an average of 31 to 60 minutes in fitness training, 28.9% (n=41) of the players spent an average of 61 to 120 minutes in fitness training, and the remaining 7.7% (n=11) of the players spent an average of more than or equal to 121 minutes in fitness training. For injured players, there are 53.9% (n=48) of the players spent an average of less than or equal to 60 minutes in fitness training, 46.1% (n=41) of the players spent an average of more than or equal to 61 minutes in fitness training. For non-injured players, there are 79.2% (n=42) of the players spent an average of less than or equal to 60 minutes in fitness training, and the remaining 20.8% (n=11) of the players spent an average of more than or equal to 61 minutes in fitness training. In order to determine if there was any significance difference in the amount of time for fitness training between injured and non-injured players, a chi square test was used. The result was found to be p= Therefore, there was significant difference

38 28 (p<0.05) in the amount of time for fitness training between injured and non-injured players. This result was shown in Table 4 and Figure 3. Table 4 Chi Square Test for the Amount of Time for Fitness Training of Injured Players and Non-Injured Players Per Week Suffered Knee Injury or Not Fitness Training (Minutes) Chi Square p Yes (n=89) (53.9%) (46.1%) No (n=53) (79.2%) (20.8%) Total (N=142) (63.4%) (36.6%) Figure 3 shows the amount of time for fitness training of injured players and non-injured players

39 29 5. Amount of Time for Weight Training of Injured Players and Non-Injured Players Apart form regular volleyball training and fitness training, all of the players also engaged in weight training. There are 41.6% (n=59) of the players spent an average of less than or equal to 30 minutes in weight training, 25.4% (n=36) of the players spent an average of 31 to 60 minutes in weight training, 22.5% (n=32) of the players spent an average of 61 to 120 minutes in weight training, and the remaining 10.6% (n=15) of the players spent an average of more than or equal to 121 minutes in weight training. For injured players, 58.4% (n=52) of the players spent an average of less than or equal to 60 minutes in weight training and 41.6% (n=37) of the players spent an average of more than or equal to 61 minutes in weight training. For non-injured players, 81.1% (n=43) of the players spent an average of less than or equal to 60 minutes in weight training, and the remaining 18.9% (n=10) of the players spent an average of more than or equal to 61 minutes in weight training. In order to determine if there was any significance difference in the amount of time for weight training between injured and non-injured players, a chi square test was used. The result was found to be p= Therefore, there was significant difference

40 30 (p<0.05) in the amount of time for weight training between injured and non-injured players. This result was shown in Table 5 and Figure 4. Table 5 Chi Square Test for the Amount of Time for Weight Training of Injured Players and Non-Injured Players Per Week Suffered Knee Injury or Not Weight Training (Minutes) Chi Square p Yes (n=89) (58.4%) (41.6%) No (n=53) (81.1%) (18.9%) Total (N=142) (66.9%) (33.1%) Figure 4 shows the amount of time for weight training of injured players and non-injured players

41 31 6. Warm up and cool down patterns of players For warm up activities before the training, most of the players 93.7% (n=133) participated in warm up activities and 6.3% (n=9) of the players didn t spend time for warm up activities. Of those who participated in warm up activities, 52.6% (n=70) of the players spent an average of less than or equal to10 minutes in warm up activities, 45.1% (n=60) of the players spent an average of 11 to 20 minutes in warm up activities and only 2.3% (n=3) of the players spent an average of 21 to 30 minutes in warm up activities. For injured players, 48.2% (n=41) of the players spent an average of less than or equal to 10 minutes in warm up activities, 50.6% (n=43) of the players spent an average of 11 to 20 minutes in warm up activities and 1.2% (n=1) of the players spent an average of 21 to 30 minutes in warm up activities. For non-injured players, 60.4% (n=29) of the players spent an average of less than or equal to 10 minutes in warm up activities, 35.4% (n=17) of the players spent an average of 11 to 20 minutes in warm up activities and 4.2% (n=2) of the players spent an average of 21 to 30 minutes in warm up activities.

42 32 To determine if there was any significance difference in the amount of time for warm up activities between injured and non-injured players, a chi square test was used. The result was found to be p= Therefore, there was no significant difference (p>0.05) in the amount of time for warm up activities between injured and non-injured players. This result was shown in Table 6 and Figure 5. For the types of warm up activities, 88.7% (n=118) of the players would do jogging, 90.2% (n=120) of the players would do stretching, and 43.6% (n=58) of the players would do specific warm up. Cool down activities after training could help your body to get recover from hard workout, 73.9% (n=105) of the players participated in cool down activities and 26.1% (n=37) of the players didn t spend time for cool down activities. For injured players, 77.5% (n=69) of the players participated in cool down activities and 22.5% (n=20) didn t participated in cool down activities. For non-injured players, 67.9% (n=36) of the players of the players participated in cool down activities and 32.1% (n=17) of the players didn t participated in cool down activities. To determine if there was any significance difference in the rate of knee injuries between the players who were participated in cool down activities and those who were

43 33 not, a chi square test was used. The result was found to be p= Therefore, there was no significant difference (p>0.05) in the rate of knee injuries between the players who were participated in cool down activities and those who were not. This result was shown in Table 7 and Figure 6. Table 6 Chi Square Test for the Amount of Time for Warm Up Activities of Injured Players and Non-Injured Players Suffered Warm up activities (Minutes) Knee Injury or Not Chi Square p Yes (n=85) 41 (48.2%) 43 (50.6%) 1 (1.2%) No (n=48) 29 (60.4%) 17 (35.4%) 2 (4.2%) Total (n=133) 70 (52.6%) 60 (45.1%) 3 (2.3%)

44 34 Figure 5 shows the amount of time for warm up activities of injured players and non-injured players Table 7 Chi Square Test for the Cool Down Habit of Injured Players and Non-Injured Players Suffered Knee Injury or Not Participated in cool down activities Yes No Chi Square p Yes (n=89) 69 (77.5%) 20 (22.5%) No (n=53) 36 (67.9%) 17 (32.5%) Total (N=142) 105 (73.9%) 37 (26.1%)

45 35 Figure 6 shows the cool down habits of injured players and non-injured players 7. Categories of knee injuries The categories of knee injury were divided in two main categories, acute injury and chronic injury. The player could suffer. more than one knee injuries within. the past one year and the injuries. could be in different categories. There were 24.7% (n=22) of the players suffered from acute knee injuries and 77.5% (n=69) of the players suffered from chronic knee injuries. For those who suffered from acute knee injuries, 31.8% (n=7) of the players were men and 68.2% (n=15) of the players were women. For those who suffered from chronic knee injuries,

46 % (n=39) of the players were men and 43.5% (n=30) of the players were women. The result was shown in Table 8. Table 8 Categories of Knee Injuries of Injured Players Sport Gender Knee Injury Category Acute No Acute Chronic No Chronic Volleyball Total (n=89) Men (n=46) Women (n=43) 15.2% 84.8% 84.8% 15.2% 34.9% 65.1% 69.8% 30.2% 24.7% 75.3% 77.5% 22.5% 8. Types of knee injuries suffered by players There were several types of knee injuries, including contusion, overuse injury, meniscus tear, ACL tear, PCL tear, MCL tear and LCL tear. Players were asked whether they have suffered from any of these knee injuries within the past one year.pl Each of them could choose more than one type of knee injury. It shows that there were 20.2% (n=18) suffered from contusion, 75.3% (n=67) suffered from overuse injury, 14.6% (n=13) suffered from meniscus tear, 21.3%

47 37 (n=19) suffered from ACL tear, no PCL tear, 3.4% (n=3) suffered from MCL tear and no LCP tear. This result was shown in Table 9. Concern about the ACL tear, there were 26.3% (n=5) of the players were men and 73.7% (n=14) of the players were women. To determine if there was any significance difference in the rate of ACL tear injury between genders, a chi square test was used. The result was found to be p= Therefore, there was significant difference (p<0.05) in the rate of ACL tear injury between genders. This result was shown in Table 10. Table 9 Types of Knee Injuries Suffered by Players Knee Injury Types Gender Total Men Women (N=89) (n=46) (n=43) Contusion 16.7% 83.3% 20.2% Overuse Injury 59.7% 40.3% 75.3% Meniscus Tear 30.8% 69.2% 14.6% ACL Tear 26.3% 73.7% 21.3% PCL Tear 0% 0% 0% MCL Tear 33.3% 66.7% 3.4% LCL Tear 0% 0% 0%

48 38 Table 10 Chi Square Test for Men and Women Volleyball Players with the Rate of ACL Tear Injury Sport ACL Tear Injury Gender Men Women Chi Square p Volleyball Yes 26.3% 73.7% (n=19) No 58.6% 41.4% (n=70) Total 51.7% 48.3% (n=89) 9. Antecedents of knee injuries Knee injuries may cause by several reasons, including inadequate warm up, poor fitness, over-trained, inattentive, collision with others, venue problem, unsuitable equipment, and others. Players were asked about the reason for their knee injuries suffered within the past one year. It could be caused by more than one reason. It shows that there were 22.5% (n=20) caused by inadequate warm up, 37.1% (n=33) caused by poor fitness, 57.3% (n=51) caused by over-trained, 30.2% (n=27) caused by inattentive during training, 27% (n=24) caused by collision with others, 5.6% (n=5) caused by venue problem and 6.7% (n=6) caused by unsuitable equipment. This result was shown in Table 11.

49 39 Table 11 Antecedents of Knee Injuries Antecedents Gender Total Men Women (n=89) (n=46) (n=43) Inadequate Warm 65% 35% 22.5% Up Poor Fitness 54.5% 45.5% 37.1% Over-Trained 54.9% 45.1% 57.3% Inattentive During 66.7% 33.3% 30.3% Training Collision with 8.3% 91.7% 27% Others Venue Problem 60% 40% 5.6% Unsuitable Equipment 33.3% 66.7% 6.7% 10. Treatment for knee injuries Players received treatments based on the severities of the knee injuries, including rest, accident &emergency, general doctor, family doctor, orthopedic doctor, physiotherapy, Chinese bone setter, acupuncture, and others. The most common treatment was rest 49.4% (n=44), followed by physiotherapy 47.2% (n=42), accident &emergency 22.5% (n=20), Chinese bone setter 14.6% (n=13), acupuncture 11.2% (n=10) were other common treatments applied. Orthopedic doctor 9% (n=8) and general doctor 3.4% (n=3) were not common

50 40 treatment applied by players. None of the players received treatment from family doctor. This result was shown in Table 12. Table 12 Treatment for Knee Injuries Treatment Gender Total Men Women (n=89) (n=46) (n=43) Rest 59.1% 40.9% 49.4% Accident & 20% 80% 22.5% Emergency General Doctor 33.3% 66.7% 3.4% Family Doctor 0% 0% 0% Orthopedic Doctor 37.5% 62.5% 9% Physiotherapy 61.9% 38.1% 47.2% Chinese Bone 38.5% 61.5% 14.6% Setter Acupuncture 20% 80% 11.2% 11. Rehabilitation of knee injuries Even injury is bane of athlete s life, we still need to overcome it. All athletes want to return to his or her pre-injury level of function after injury. For some serious knee injuries such as tear in ligament, surgery was required as a treatment to help rehabilitation.

51 41 Refer to the result, 18% (n=16) of the injured players receive surgery as part of the treatment of their knee injuries. Of those who receive surgery, 6.3% (n=1) of the players were men and 93.8% (n=15) of the players were women. This result was shown in Table 13. Concerning about the severity of the knee injuries, the injured players required different amount of time for recovery. 11.2% (n=10) of the players spent less than or equal to one week for recovery. 38.2% (n=34) of the players spent 2 to 33 weeks for recovery. 13.5% (n=12) of the players spent 4 to 5 weeks for recovery and 37.1% (n=33) of the players spent more than or equal to 6 weeks for recovery and returned to regular training. This result was shown in Table 14. Table 13 Number of Knee Injuries requiring Surgery Sport Gender Surgery Yes No Volleyball Men (n=46) Women 2.2% 34.9% 97.8% 65.1% (n=43) Total(N=89) 18% 82%

52 42 Table 14 Amount of Time for Recovery of Injured Players Sport Gender Recovery Time 1 week 2-3 weeks 4-5 weeks 6 weeks Volleyball Men (n=46) Women 19.6% 2.3% 39.1% 37.2% 8.7% 18.6% 32.6% 41.9% (n=43) Total (n=89) 11.2% 38.2% 13.5% 37.1%

53 43 Chapter 5 DISCUSSION AND CONCLUSION A total of 142 volleyball players responded in this study. The result was used to give a better understanding of the demographic effects on knee injuries, patterns of knee injuries, causes of knee injuries, rehabilitation of knee injuries of volleyball players in Hong Kong. The target group and sample size were different from similar studies that have been conducted before. Therefore, it still be worth discussing between studies. 1. Knee Injuries of Men and Women Volleyball Players The researchers thought that female players might might have a higher chance to get knee injury compare to their male counterparts due to the biomechanical factor. However, refer to the result of this study, there was no significant difference (p>0.05) in the knee injuries between men and women volleyball players (p=0.46). Bere (2015) also showed that there was no significant difference between males and females in the international volleyball competition. Some studies revealed that female volleyball players could have higher risk for acute knee injuries than male volleyball players. Due to the significantly higher H: Q

54 44 strength ratios, it would be the possible factor to explain the difference in knee injury incidence between male and female volleyball players. Males demonstrated significantly higher H: Q strength ratios compared to females (Anderson et al., 2001). Sex-related differences in landing technique was not the major reason, male players landing from greater heights causing higher patellar tendon loading. Male players suffered from higher patellar tendon loading which would cause higher knee injury incidence rate than female players (Janssen, Steele, Munro, & Brown, 2014). 2. Fitness Training and Weight Training Many researchers suggested that fitness training and weight training could help reduce the incidence of sport injuries. Nowadays, it is not surprised that all of the players were engage in fitness and weight training to help enhance their performance. To reduce the risk of knee injuries and maintain normal knee function, a balance between the quadriceps and hamstring muscles is important. Reilly (1992) suggested that the stability of a joint could be increased by muscles that crossed the joint. The stability of the knee joint could therefore be increased by strengthening the quadriceps

55 45 which secures the joint together with the cruciate ligaments and collateral ligaments (Reilly, 1992). Other than strengthening muscle that across the knee joint, Prentice (2008) found that improving the body conditioning such as flexibility, cardiovascular endurance, muscular endurance, agility, speed, and balance could help to prevent knee injuries (Prentice, 2008). For the relationship between the rate of knee injuries and the frequency of fitness training and weight training, the result showed that there was significant difference in the amount of time for fitness training (p=0.002) and weight training (p=0.005) between injured and non-injured players. Gabbet & Domrow, (2007) found that reductions in training load during the early-competition training phase can reduce the odds of injury without compromising agility performances (Gabbett & Domrow, 2007). 3. Warm Up and Cool Down Patterns of the Players Most of the players (93.7%) participated in warm up activities before training. It helped to rise muscle temperature which had a significant effect on muscle function, power production and reduce the rate of injury. The warm up and cool down before and after a class would decreases the rate of injuries. The result showed that there was

56 46 no significant difference (p=0.175) in the rate of knee injuries between different frequency of warm up activities, also no significant difference (p=0.207) in the rate of knee injuries between the players who were participated in cool down activities and those who were not. When the warm up and cool down session is about 15 minutes, the number of injured appears significantly smaller. In other words, improve in flexibility can prevent from injury conditions, while the appropriate warm up and cool down prepares the muscle groups for the different types of exercise (Malliou, Rokka, Beneka, Mavridis, & Godolias, 2007). 4. Patterns of Knee Injuries of the Players The occurrence of chronic knee injuries was more frequent than that of acute knee injuries. Many researchers stated that patellar tendonitis was the most common types of overuse knee injury in volleyball due to the patellar tendon loading generated from repeatable jumping and landing. (Janssen et al. 2014) Among all types of knee injuries in this study, the result showed that there were 75.3% of the players suffer from overuse injury within the past one year. Due to the high intensity and frequency of the university team, Division I volleyball club and even Hong Kong volleyball team training, they would easily develop overuse injury in their knees. Anterior cruciate

57 47 ligament (ACL) injury (21.3%) and contusion (20.2%) were the next most common types of knee injuries. ACL injuries were occurred with less frequency but often carry more significant health consequences. ACL injury usually occurred under acute situation and it was more likely to occur in female players. In this study, there was significant difference (p=0.031) in the rate of ACL tear injury between genders. According to Nora & Aartan, (2015), quadriceps strength asymmetry was related to acute knee injuries. Females consistently have weaker hamstring muscles relative to their quadriceps as compared with their male counterparts, and this imbalance increases risk of ACL tear. Also, the degree of knee flexion was important when concern about ACL loading. When the knee flexion angle increased, the pressure on ACL would decrease. Both stick landing and step back landing may result in ACL injuries. However, the back-stepping limb may be exposed to a greater risk of ACL injury during the initial impact phase after a step-back landing (Zahradnik, 2015). 5. Antecedents of Knee Injuries The cause of knee injuries was related to the most common types of knee injury that players suffer within the past one year. According to the result, it showed that