Friday, June 24, 2011

Avoiding the Pre-Season Injury Bug

As the fall approaches, players begin preparing for the upcoming soccer season. Pre-season training is a time to develop fitness, fine-tune technical skills and improve tactical abilities. It can be a physically demanding time of the player’s year. Unfortunately, it is also a time where injuries can be a problem. Studies of soccer as well as other sports show that athletes tend to be more susceptible to injuries during the pre-season than at other times during the year. This is true for muscle and joint injuries as well as overuse injuries. A recent study focused on the incidence of injury in youth players during pre-season training. The results show that young players are quite susceptible to certain types of injuries during this period. This study, coupled with the results of others provides some insight into how the risk of injury might be reduced.

The study, published in the Clinical Journal of Sports Medicine, examined the incidence of various injuries during the soccer pre-season period. It focused on “sub-elite” youth players from 40 different teams in the U13-U19 age groups. Each team trained 3-4 times per week during the 6-week pre-season period and played several matches. Injuries that required a player to miss at least one day of training were recorded along with the type of injury, the body part injured along with the number of days sidelined.

The researchers found that, on average, each team suffered 1-2 injuries during the preseason period. Of the injuries recorded, 34% required players to miss only a single day of training. However, 55% forced them to sit out for 8 or more days. To put it into a team perspective, more than half of the teams had at least one player miss more than a week of training due to an injury.

The most common injury was a "thigh muscle" strain (this was most likely hamstring strain or pulls). Bruises were almost as common with ligament sprains the third most likely to have occurred. This is consistent with other research studies of professionals that show pre-season is a time where players are very susceptible to hamstring injuries. Studies also show that players who suffer a hamstring strain are far more likely to re-injure the muscle during the next year. Thus, the impact of a pre-season hamstring injury can extend well beyond the immediate recovery period.

This raises the question as to how best to prevent pre-season injuries, particularly hamstring injuries. Unfortunately, only a handful of studies focused on hamstring injury prevention have been published. A few studies provide some insight but most of the recommendations are based on reducing the risk factors. Researchers in Greece found that hamstring injury risk is associated with lack of hamstring strength, flexibility and neuromuscular control. Fatigue also seems to play a role. Most importantly, the lack of hamstring strength, particularly eccentric strength, creates a muscle imbalance with the quadriceps muscles. That is, weak hamstrings coupled with strong quadriceps seem to be a key risk factor.

Using this information, hamstring injury prevention should include exercises designed to strengthen the hamstrings and increase hip range of motion (i.e. flexibility).  For example, exercises such as Russian curls will increase eccentric strength,  while static and dynamic stretching will improve flexibility. Researchers in Germany also suggest that training include balance and agility activities such hopping and jumping exercises along with balancing on one foot.

Coaches should be aware that hamstring injuries often occur when players are fatigued. Gradually increasing fitness over the pre-season may reduce the risk of injury. Avoiding high speed sprinting and other “high risk” activities when players are fatigued might also help.

Players can also play a role in injury prevention. They can reduce their risk by using the off-season to correct certain risk factors. Improving hamstring strength and flexibility during summer months, before pre-season begins can go a long way towards preventing injury. Including balance and agility training can also help with injury prevention as well as improve other aspects of their game.

Interestingly, the training components listed above are included in most anterior cruciate injury prevention programs. For example, FIFA’s 11+ recommends hamstring strengthening and flexibility training as well as balance and agility training. This program is designed as a short (15-20 minutes) warm-up program to be used at the start of each training session. Several research studies have shown that it is effective in reducing he risk of ACL injury as well as improving various components of soccer performance. Thus, including this type of training as a part of a pre-season program can reduce the risk of both knee and hamstring injuries and improve performance the field.

Avoiding the injury bug is an important part of pre-season training. Not only can a severe hamstring pull sideline a player for more than a week, it can be a recurrent problem for much of the season. Given that players are susceptible to these injuries during pre-season training, coaches should focus on prevention and avoid placing players at risk (such as high speed sprinting when they are fatigue). Hopefully, these strategies will prevent players from missing this important period of preparation for the upcoming season.

References:

Brito J, Rebelo A, Soares JM, Seabra A, Krustrup P, Malina RM (2011) Injuries in youth soccer during the preseason. Clinical Journal of Sports Medicine, 21:259-260.

Croisier J-L, Ganteaume S, Binet J, Gentry M, Ferret J-M (2008) Strength imbalances and prevention of hamstring injury in professional soccer players: A prospective study. American Journal of Sports Medicine, 36:1469-1475.

Elliott MC, Zarins B, Powell JW, Kenyon CD (2011) Hamstring muscle strains in professional football players: a 10-year review. American Journal of Sports Medicine, 39: 843-850

Fousekis K, Tsepis E, Poulmedis P, Athanasopoulos S, Vagenas G (2011) Intrinsic risk factors of non-contact quadriceps and hamstring strains in soccer: a prospective study of 100 professional players. British Journal of Sports Medicine, 45: 709-714.

Heiderscheit BC, Sherry MA, Silder A, Chumanov ES, Thelen DG (2010) Hamstring strain injuries: recommendations for diagnosis, rehabilitation, and injury prevention. Journal of Orthopedic and Sports Physical Therapy, 40: 67-81.

Kraemer R, Knobloch K (2009) A soccer-specific balance training program for hamstring muscle and patellar and Achilles tendon injuries: an intervention study in premier league female soccer. American Journal of Sports Medicine, 37: 1384-1393