Preventing Volleyball Injuries: Knees, Ankles, and Stress Fractures

Transcription

1 Preventing Volleyball Injuries: Knees, Ankles, and Stress Fractures William W. Briner, Jr., MD, FACSM,FAAFP, Head Team Physician, U.S. Volleyball National Teams and Flavia Pereira Fortunately the risk of injury in volleyball is lower than that of most other sports. Women s volleyball had the second lowest injury rate during competition among 15 sports studied by the NCAA. Serious injury resulting in many days missed from training is also thankfully rare. While these statistics are reassuring, they offer small solace to a team that loses a starting player to injury before an important match, or for an entire season. If there were strategies that could be employed to further reduce injury risk, most coaches would be interested in using them. Fortunately, there are some strategies for volleyball injury prevention that can be gleaned from the sports medicine literature. The NCAA Injury Surveillance System (ISS) is the most comprehensive database available for assessing injury risk. The ISS defines injury as a traumatic incident that results in time lost from at least one practice or competition. The ISS has provided current and reliable statistical data on injury trends in intercollegiate athletics since 1982, with injury rates given for each exposure during practice or competition. The last ISS report, from 1988 to 2004, showed football had the highest rate of injuries with 36 per 1,000 games and 9.6 per 1,000 practices. Women s soccer was next with rates of 16 and 5.27 injuries per 1,000 games and practices, respectively, followed by women s gymnastics then women s basketball.

2 Women s volleyball had just 4.10 injuries/1,000 practices and 4.58 injuries/1,000 competitions. The main focus here is to review the concepts behind a successful injury prevention program in volleyball athletes, particularly ankle sprains, patellar tendonitis, ACL tears, and stress fractures. Important concepts for coaches are primary and secondary injury prevention, pain vs. injury, jump rate, stretching, and overuse injuries in volleyball players. These concepts should help build framework for injury prevention in volleyball. Primary prevention is defined as measures taken to prevent injury before it ever occurs. This type of prevention is essential for severe season ending injury such as anterior cruciate ligament (ACL) injury. Secondary prevention focuses on preventing a reinjury after a previous injury has occurred. Studies have shown this to be the most effective type of prevention for ankle sprains. Volleyball injury studies suffer from the same problem that is seen in injury data in many sports, namely a lack of a consistent definition of injury. In 1992, Schafle found an injury rate of 1per 50 hours among participants in the 1987 U.S. Open Amateur Volleyball Tournament. She defined injury as any condition for which a player sought medical evaluation. Using a similar definition, at the 1995 U.S. Olympic Festival, the rate was 1 injury per 25 hours of practice and competition. These athletes were NCAA All American level players, who may have subjected themselves to greater stresses during competition, increasing their injury risk. Perhaps these athletes pain tolerance also played a role in their higher injury rate.

3 There are data to show that athletes may have a higher tolerance for pain than nonathletes, which in turn can make it difficult to sort out the difference between pain and injury. The difficulty of this distinction has been demonstrated in volleyball players. The International Volleyball Federation(FIVB) conducted a study of players on the FIVB beach tour in A vast majority of athletes were playing with pain in their lower back, shoulders, and/or knees. However, only a few of these athletes had seen a physician or had taken time off from training. Some were even considering surgery during the off season. So there certainly may be situations when it makes sense to try to prevent injury before an athlete presents to the medical staff an incident that would be defined as an injury. Jump rate is a major concern for volleyball players, and is a significant contributor to injuries in all sports. In 1991, Backx, et al., investigated Dutch school children and found those who participated in sports with the highest jump rate had the greatest chance of being injured. Of course, volleyball is the sport with the highest jump rate, and in this study volleyball practice had the highest injury rate of any sport activity. Goodwin Gerberich, et al., in 1987, evaluated the records of 106 patients treated for volleyball injuries and found that 63% were associated with jumping or landing. It may be that volleyball players spend more time stretching than they need to. The sports medicine literature on stretching has not shown that it is necessarily beneficial in preventing injury. According to recent comprehensive reviews, static stretching does not seem to prevent injury. Static stretching is the time honored

4 practice of holding a joint at the limit of its range of motion for several seconds. Dynamic stretching involves placing a joint on stretch, then moving it up and back (sagittal plane), side to side (coronal plane) and in a rotational motion (transverse plane). Dynamic stretching is more functional for athletic movement, and physical therapists feel that it is superior in improving range of motion. Studies have also shown that it can improve muscle strength and performance to a greater extent than other types of stretching, especially in high level athletes. It also takes less time than static stretching. Warm muscles can be stretched more effectively, so a reasonable recommendation might be five minutes of warmup, using the muscles involved in volleyball (jogging, shuffling, carioca), followed by five minutes of dynamic stretching at the start of practice. A few minutes of dynamic stretching at the end of practice is also a good idea, because muscles adapt to a shorter functional length during training. 1 The Coronal Plane divides the body into front and back halves.

5 2 The Sagittal Plane divides the body into left and right halves. 3 The Transverse Plane divides the body into upper and lower halves Lastly, a major risk factor for the development of injuries is the volume of training or number of repetitions of a given skill which results in overuse injuries. Such injuries occur for two reasons. The first is tissue that fails because of weakness. This failure often occurs at the growth plate of long bones in athletes in their early teens. Injury may also result from overstress to normal tissue, which may occur if too many repetitions are performed without enough rest in between. Rest should be incorporated into each training session, between sets of multiple repetitions; each week, taking a day off or scheduling lighter training sessions during competition; and each year, giving players time off before they return to training. As noted above, it is particularly important that players rest from jumping during the course of each year. When the stress is applied at a rate exceeding that of tissue repair, progressive damage occurs to the structures at risk. Club volleyball players may be particularly at risk for overuse injuries since the growth plates in their bones are still open. If they experience year round stresses through their high school and club seasons, these vulnerable structures are subject to greater risk of injury. Hopefully, it will not be a controversial recommendation to suggest that high school athletes be given three months off after their fall season. If the junior clubs could all agree to start practice in mid February, it would give the players bones and soft tissue the chance

6 to recover. This could significantly decrease the risk of injury for these young athletes. Ankle Injuries The ankle is the most common site for acute injury in volleyball players. This injury accounts for 30% of time loss injuries and can result in significant downtime from volleyball. Ankle sprains usually occur at the volleyball net when a player lands on the foot of an opponent or teammate after blocking or attacking. A primary prevention suggestion has been to change the centerline rule, so any contact with the line would be considered a violation. In Norway, this rule was experimented with for several weeks. The study found a two fold decrease in ankle sprains; however, the experiment had to be abandoned because players felt that too many interruptions in play occurred. The authors suggested that avoiding any contact with the center line during practice would decrease ankle sprain risk. It may also be reasonable to suggest this rule be used during warm ups. Players should be aware that when they hit a ball and then duck under the net they are practicing for their next ankle sprain. The most common risk situation in this study involved tight sets, when an attacker broad jumps and lands across the center line, and the opposing blocker lands on her foot. These problem attackers can be coached to take a longer final approach step and jump up instead of forward. It is usually easy to convince attackers to do this, since this technique results in a higher jump and greater chance of winning the point. Ankle sprains are much more likely to recur during the first year following an initial injury. Compared to an ankle with no prior injury, the risk of injury is fourfold

7 greater for an ankle that has been previously sprained. A secondary prevention program is crucial in order to decrease this risk of re injury. A ten week program of balancing and strength training for the foot and ankle has been shown to decrease the chance of recurrent ankle sprain. Ten minutes daily of neuromuscular rehabilitation, such as balance board training, decreases the risk of ankle sprain to almost the same level as an ankle that has not been previously injured. These programs can be designed by a sports medicine physician, certified athletic trainer or physical therapist. Finally, the use of ankle braces and taping have been widely investigated. Taping and bracing seem to increase proprioceptive awareness in the ankle joint, and these effects seem to be limited to athletes with previous injury. Stirrup braces, such as the Active Ankle or, have the best data to support their use in decreasing the chance of recurrence of injury, especially during the first year after a sprain. Knee Injuries Patellar tendinosis/tendonitis is the most frequent overuse injury in volleyball. The most common site for pain is at the bottom of the kneecap, where the tendon originates. Tendinosis is the more accurate term since the injured tendon actually consists of fibrosis or scar tissue, not inflammatory cells. Volleyball athletes at all levels are committed to jump training as part of their regimen, perhaps more so than athletes in any other sport. The biggest challenge for coaches and strength and conditioning personnel seems to be finding the fine line between performance enhancement and risk of injury. If we could clearly define this line for each athlete, it would be easier to prevent tendinosis. Athletes who generate the greatest power

8 during vertical jumping seem to be at greatest risk. Since these are the athletes who already jump the highest, it may be advisable for them to devote less time to jump training and plyometrics. Athletes with increased external tibial torsion and deeper than 90 degree knee flexion at takeoff are also at increased risk. So coaching attention to technique and amount of time spent jump training should help decrease the risk of patellar tendinosis. Adequate strength training prior to high impact jump training and plyometrics is believed to be an important part of decreasing the risk of tendon injury. An essential emphasis when the focus is on prevention of kneecap tendinosis, is to eccentrically load the muscles during strength training. This means working the negative during resistance exercise. This is best done in a closed chain fashion, with the foot in contact with the ground. So leg presses, for example, are much more beneficial than quadriceps extensions. Wall slides are a simple preventive exercise that does not require any special equipment. The athlete starts with her knees straight and back flat against a wall, then slowly slides down the wall into a wall sit position, holding for few seconds, then sliding back up; she should do two sets of 15 repetitions. Half squats and power clean exercises may also be beneficial, but athletes must be coached to emphasize the negative phase of the contraction going up fast and down slowly, work against gravity on the way down. Some evidence suggests that volleyball injury is less likely to occur on softer surfaces. The 1995 U.S. Olympic Festival participants reported five fold fewer injuries per hour playing on sand than on hard court surfaces. Doing plyometric or jump training on sand should help to decrease the risk of tendinosis.

9 Biomechanically correct landing may help to decrease the incidence of patellar tendon problems, and it has also been shown to decrease the chance of anterior cruciate injury. According to NCAA Injury Surveillance data, the frequency of ACL injury is considered lower in volleyball than in most other team sports. Ferreti et al. reported on 52 serious knee ligament injuries and found the most common mechanism of injury was landing from a jump in the attack zone. Most of these involved the ACL and there were more women than men in this case series. There are certain athletes who may be at greater risk, and who should be targeted for an ACL injury prevention program. Coaches should pay special attention to girls whose knees come together in knock kneed fashion when landing from a jump. A simple screening test is to have the athlete jump from an 18 inch box and observe her landing. If the knees come in towards each other, kissing knees, then the ligaments are absorbing too much of the landing forces. This has been referred to as ligament dominant landing, which puts the ligaments at greater risk. Girls who land with their knees straight, in extension, also seem to be at increased risk. A prevention program should emphasize strengthening the hamstring muscles, since those muscles work in conjunction with the ACL. The hamstrings can be trained to fire rapidly during landing from a jump, making the ACL less vulnerable. Hitters often reach high with their hitting hand and shoulder, so that the foot on that side is lifted higher up off the ground. Then they land on their opposite leg, putting that ACL at greater risk. However, there is no advantage to be gained from landing on one foot, so hitters should be coached to land with both feet together, to effectively dissipate landing forces. There are also studies that show that if players try to land

10 softly like a feather, there is less force transmitted to the joints in their legs. So players should land softly, with both feet at once, and their knees bent directly over their feet. There are even some data to suggest that this sort of landing maximizes eccentric training of the muscles used in jumping, resulting in greater jumping power. For a variety of reasons, it may be just as important to coach players on how they land as it is to train them how to jump. Stress Fractures A stress fracture is the inability of the skeleton to withstand repetitive bouts of mechanical loading, which results in structural fatigue, causing bone pain. If these forces continue, the bone cortex may fail and a true fracture will occur. Volleyball players appear to be at an increased risk for developing lower limb stress fractures, as well as lumbar spine spondylolysis, which is essentially a stress fracture in the pars interarticularis of the vertebra in the low back. This type of injury may occur in athletes who increase their volume of training quickly or continue training through muscle fatigue. Ideally, landing forces are absorbed by muscles, but as the muscles fatigue they become less effective shock absorbers. The consequence is that landing forces are transmitted to the bones causing a greater load which results in stress fracture. Women are more likely than men to get stress fractures, possibly because of the female athlete triad. The three aspects of the triad are: 1) oligoamenorrhea less frequent menstrual periods during training; 2) disordered eating when athletes take in inadequate calories for their energy needs; and 3) osteoporosis bone mineral loss. Any volleyball player suspected of having any of these three

11 conditions should be evaluated by a primary care sports medicine physician. A multidisciplinary treatment program may help to decrease the risk of stress fracture. A common method of training used to increase vertical jump in volleyball athletes is plyometrics. When done correctly, plyometrics have been shown to improve vertical jump, while decreasing stress to the bones, probably because of the maximal eccentric contraction prior to takeoff. However, teams often see increased stress fracture rates with a new plyometric program. The reason might be that tired muscles are stressed beyond the point where they can function as effective shock absorbers. What makes a plyometric program safe? The first step is to do adequate strength training prior to starting a program. Not all strength coaches agree on how strong is strong enough. A conservative recommendation might be for the athlete is able to perform two sets of 10 leg presses with twice her body weight. Her landing form should be biomechanically correct, as noted in the previous section. Athletes should take at least one day off in between sessions, and they should not perform plyometrics more than two or three times in a week. Plyometrics should be done early in practice, when muscles are fresh, and jump training should never be used for fitness training. Conclusion Injuries are almost an inescapable aspect of sports. Fortunately, the risk of injury in volleyball is among the lowest of the team sports. The most common acute injuries seen in volleyball are ankle sprains. Ankle re injury can be prevented with a rehabilitation program including balancing exercises and a stirrup type ankle brace.

12 Patellar tendinosis/tendinitis is the most frequent overuse injuries in volleyball. Adequate strength training and careful attention to the volume of jumping, as well as rest from jumping during training, may minimize the risk of this injury. ACL injury risk can be decreased by targeting athletes with flawed biomechanics of jumping and emphasizing correct landing technique with them. Similarly, stress fracture risk can be deceased by allowing enough rest, especially from jumping during the competitive season. Certified Athletic Trainers are often familiar with these injury prevention principles. Involving them in the strength and conditioning program of a volleyball team may be an effective way to minimize injury risk.