Skating Strong : A New Approach to Groin Injury Prevention
Well, it’s that time of year again – the physiotherapists start to lick their chops in anticipation of the start of fall and winter sporting events. The excitement is obvious as the rather laid back summer activities get traded in for skates, skies, and of course – injuries. More specifically, skating sports such as hockey, speed skating, and cross-country skate skiing, see a very high incidence in groin injuries (Quinn et al., 2003; Tyler et al., 2001). Although there are many injuries that occur at the origin point of the groin muscles (stress fractures, avulsion fractures, osteitis pubis, sports hernia, etc.), adductor strains are the most common (Maffey & Emery, 2007). The groin muscles include the adductor brevis, longus, and magnus, the gracilis, and the pectineus which together flex, adduct, and medially rotate the thigh. The vast majority of these groin injuries are caused by the adductor muscles being put under a high eccentric load before having to decelerate (or accelerate in the opposite direction) and quickly shorten in an explosive concentric manner (Lynch & Renstrom, 1999). This can be seen when watching Cindy Classen drive her skate into the ice (abduction/extension) before quickly pulling (adduction/flexion) the femur back and ready for the next stride. Similarly, every time Roberto Luongo recovers from a butterfly, he has to drive his outside skate into the ice so that he can push across his crease in time for the next shot.
Some of these injuries are bad luck – the result of pushing off with the skate or ski, only to have it slip and not dig in. Because of the speed of the movement, the brain “thinks” or “assumes” that the skate will dig in, creating a nice surface to drive off of. However, when the slip occurs, the abductor group continues accelerating while the smaller adductor muscles go through a very powerful eccentric force, sometimes too large for this group to handle. Quite often however, groin injuries can be chronic injuries that seem to resurface time and time again during a competitive career.
Risk Factors
There are many risk factors that have been identified in the research that increase the likelihood of sustaining a groin strain in skating sports. These include previous injury, increased age (or number of years played), strength imbalances in both legs, increased abductor to adductor strength ratio, poor core stabilization, lack of sport-specific adaptation training, and poor adductor eccentric strength (Maffey & Emery 2007). Notice that adductor length has not been included in the list of risk factors. There has been some support for opposing muscle (hip abductors and quadriceps) length as a risk factor (Gabbe et al, 2005), indicating that hip flexibility should focus more on these muscles groups rather than the hip adductors.
As a strength coach, you need to address these risk factors, each weighted based on importance. Previous injury is usually something you have no control over. However, you can still learn from this information, and target the individual as “at risk” for future lower extremity injuries. Age or sport experience is again something out of your control but note that the older the athlete gets, the more detail and effort must go into implementing their training program.
Strength imbalances between legs should be recognized in the initial assessment of the athlete and addressed immediately in training. Unilateral strength training involving slow, controlled lifts will help to equalize the two limbs and improve movement economy. Similarly, although the need for abductor hip strength/power is crucial for success in skating sports, the opposing adductor group must not be far behind in order to reduce the risk of injury (Tyler et al 2001; Tyler et al, 2002).
Core stability, eccentric training, and dexterity training are three methods to help decrease some of the more controllable risk factors such as non-sport-specific adaptations, a large abductor:adductor ratio, and poor core stabilization.
Core Stability
Every athlete can benefit from proper core stabilization training. Most of the research that has been done on core stabilization and groin injuries has focused on implementing programs based on unstable surface training (BOSU, stability balls, balance boards, etc.). Although research has shown an increase in core muscle activation in a relatively static state, this does not cross-over to dynamic stabilization of movement (Cressey et al., 2007). Moreover, for the most part, skating sports occur on flat surfaces with the ankle joint fairly fixed in a boot; with unstable surface training, the foot is often placed in an awkward position, leading to an increased risk of injury.
Core stability has been shown to decrease injury in most sports, but specific to skating, it is proposed that a fair amount of groin pain results from the inability to transfer load properly from legs/torso to the hips (Ekberg et al., 1988; Meyers et al., 2000; Williams et al., 2000). As a strength coach you need to integrate core stabilization into primal movements and patterns specific to skating. It is one thing for a speed skater to be able to hold a front or side plank for 3 minutes, but it is another to decelerate quickly into a lateral lunge and power back while fatigued. The athlete must be able to brace under load to produce safe, powerful movements or else all that mat-based core work will go to waste.
Eccentric Strength
Eccentric strength training addresses a number of different risk factors: strength imbalances between legs, increased abductor to adductor strength ratio, lack of sport-specific adaptation training, and poor adductor eccentric strength. Previous research in hamstring injuries has indicated the importance in eccentric hamstring strength for avoiding hamstring strains and ACL injuries (Proske et al, 2004). This increase in hamstring eccentric strength increases their optimal length (force vs. length curve) resulting in the muscle group generating a greater force at a greater length – which means less incidence of hamstring strain.
So, why can’t we do this for hip adductors as well?
There hasn’t been a lot of attention given to eccentric training of hip adductors when it comes to addressing strength in the groin. Most of the protocols that have come from research have focussed on concentric strength. Plyometrics is one of the most effective training protocols in developing specific eccentric strength and rate of force development. In addition to weighted eccentric work, plyometric training allows the muscle (group) to undergo a very rapid stretch (eccentric), before transitioning (regaining potential energy) to a very explosive shortening (concentric) of the muscle. Lateral bounds, zig zags, angled lateral jumps, and cutting drills are great examples of plyometric exercises for the hip. Focus must be on making each jump as powerful as possible.
Weighted eccentric exercises are a little more complicated when it comes to the groin. Bands are often used as a training tool for eccentric training, however, as the groin is stretched (eccentric portion), the band gets shorter and thus provides less and less resistance (Emery, 2008). With eccentric training, the load needs to be significant and consistent to have the desired effect. One way to attempt this is using the cable pulley system. Attach the cable to the inside ankle and walk away (so the side of you faces the stack). Have a qualified strength coach holding your leg in neutral. As the coach lets go of your leg, your goal is to slow it down as it is being pulled back to the stack. To have a true eccentric effect, the weight should be heavy enough so that you cannot concentrically pull the leg back to the middle (coach returns the leg).
Sumo squats and deadlifts are a nice adjunct to plyometrics as they provide a wider stance in order to put the adductors on stretch. In addition, you are still getting the benefit of posterior chain strength – a necessity in skating sports. Weighted lateral lunges are also great for deceleration training, however, they focus more on the abductors; make sure you balance out the adductor strength with the above lifts to improve that abductor:adductor ratio.
Dexterity training
Now before you start doing finger push-ups, think again. Dexterity training as it applies to strength & conditioning is developing “a motor solution to a motor problem” (Bernstein, 1996). Because motor problems within sport are usually quite unpredictable as in hockey, we as strength coaches need to develop techniques and pre-habilitation programs that attend to as many contexts as possible (Moreno, 2008).
Oh great, so let’s get out the agility ladders right? Well, not exactly. Traditional coordination and agility training involves predetermined conditions to be performed as quickly as possible. With dexterity training, you want to create an unpredictable or chaotic environment. This can be done in conjunction with your plyometric training. For example, while your athlete is in mid-air during a vertical jump, point to a spot in which they must cut to upon landing. The objective is for the athlete to land, plant, and cut as quickly as possible while not having the luxury of a pre-planned movement pattern. This can also be done during on-ice sessions for goaltenders in hockey. Have the goalie perform continuous lateral pushes from a butterfly position. Tap your stick once to change direction, and twice to pop up into a stance. Although this will not eliminate situations such as losing an edge, it will better prepare your nervous system for the sporting environment.
So, whether you’re training a hockey player, skier, speed skater or other type of skater, keep in mind the importance of keeping healthy groin musculature.
References
Bernstein, N.A. (1996). On dexterity and its development. In Latash, M.L. and Turvey, M.T. (Eds), Dexterity and its Development. New Jersey, Lawrence Eribaum Associates.
Cressey, E. M., West, C. A., Tiberio, D. P., Kraemer, W. J., & Maresh, C. M. (2007). The effects of ten weeks of lower-body unstable surface training on markers of athletic performance. Journal of Strength & Conditioning Research, 21(2), 561-567.
Ekberg, O., Persson, H. H., Abrahamsson, P. A., Westlin, N. E., & Lilja, B. (1988). Longstanding groin pain in athletes. A multidisciplinary approach. / douleur persistante a l ' aine chez des athletes: Approche multidisciplinaire. Sports Medicine, 6(1), 56-61.
Emery, J. (2008). Groin pulls in hockey: An intervention to lower the risk. Human Motion: The Performance Advocate. Retrieved from www.humanmotion.ca
Gabbe, B. J., Finch, C. F., Bennell, K. L., Wajswelner, H., & Orchard, J. W. (2005). RISK FACTORS FOR HAMSTRING INJURIES IN AUSTRALIAN FOOTBALL. (abstract). British Journal of Sports Medicine, 39(6), 385-385.
Lynch, S. A., & Renström, P. A. F. H. (1999). Groin injuries in sport: Treatment strategies. Sports Medicine, 28(2), 137-144.
Maffey, L., & Emery, C. (2007). What are the risk factors for groin strain injury in sport? Sports Medicine, 37(10), 881-894.
Meyers, W. C., Foley, D. P., Garrett, W. E., Lohnes, J. H., & Mandlebaum, B. R. (2000). Management of severe lower abdominal or inguinal pain in high-performance athletes. / diagnostic et traitement d'une douleur severe dans le bas du ventre ou inguinale chez des athletes de haut niveau. American Journal of Sports Medicine, 28(1), 2-8.
Proske, U., Morgan, D., Brockett, C., & Percival, P. (2004). Identifying athletes at risk of hamstring strains and how to protect them. Clinical & Experimental Pharmacology & Physiology, 31(8), 546-550.
Quinn, A., Lun, V., McCall, J., & Overend, T. (2003). Injuries in short track speed skating. American Journal of Sports Medicine, 31(4), 507-510.
Tyler, T. F., Nicholas, S. J., Campbell, R. J., Donellan, S., & McHugh, M. P. (2002). The effectiveness of a preseason exercise program to prevent adductor muscle strains in professional ice hockey players. / fiabilite d ' un programme d ' exercices de pre-saison pour prevenir les lesions musculaires aux adducteurs chez des joueurs de hockey sur glace professionnels. American Journal of Sports Medicine, 30(5), 680-683.
Tyler, T. F., Nicholas, S. J., Campbell, R. J., & McHugh, M. P. (2001). The association of hip strength and flexibility with the incidence of adductor muscle strains in professional ice hockey players. / L'association de la force et de la flexibilite de la hanche joue-t-elle un role dans l'incidence d'une elongation du muscle adducteur chez des joueurs professionnels de hockey sur glace? American Journal of Sports Medicine, 29(2), 124-128.
Williams, P. R., Thomas, D. P., & Downes, E. M. (2000). Osteitis pubis and instability of the pubic symphysis: When nonoperative measures fail. / osteite du pubis et instabilite de la symphyse pubienne: Lorsque les mesures non-operatoires ne fonctionnent pas. American Journal of Sports Medicine, 28(3), 350-355.
