What's the Squeeze on These Adductor Strains?

If you have been paying attention to the 2021 MLB season, you have likely read articles on a rash of injuries.  Although the reasons behind such an onslaught of lost playing time remain unclear, one feature contributing to the injury data could be brief periods of inactivity, potentially caused by COVID outbreaks, where teams disperse until the medical staff can take control of contact tracing and protocols to establish a safe return back to the daily grind.  In conversations I have had with people around the league, issues with COVID outbreaks were especially apparent in Spring Training when many of the athletes were not vaccinated.   

One of the more common injuries seen this year has been hip adductor strains to pitchers who drive down the mound.  Hip adduction training (squeezing exercises between the knees) is not as frequently prescribed in comparison to hip abduction training (resistance applied to the outer muscles of the thigh that are integral to lateral push-off).  Another issue with traditional hip adduction training is that resistance is usually applied through a flexed hip (thighs parallel to the ground).  One of the notable training options is the seated hip adduction machine where you bring your knees together against a resistance.  Although this form of training is beneficial for pitchers, the force application is generally slow with little attention paid to eccentric training with the hip in a neutral position or with the hips being slightly extended that is more specific to pitching for the drive leg. 

The mechanism of hip adduction strains is much like any other strain-related injury.  High rates of tensile loading, being a rapid lengthening, eccentric contraction, can overwhelm the muscle and tendon’s ability to withstand it.  As a result, the tissues strain and cause pain typically near the groin. 

Biomechanically, the ankle, knee, and hip, create a corkscrew extension-like interaction as the foot is creating a frictional torque with ground while the knee and hip are extending.  The interconnection of ground reaction force with knee and hip extension do not merely incorporate linear forces, but also a type of ground reaction force application that is torsional.  As the cleats dig in and friction increases as the pitcher is going down the mound, knee-to-knee separation increases until a point where rapid knee extension of the drive leg occurs just before the cleats disengage and the heel turns over as the athlete transfers weight to the lead side.  It is believed that this endpoint knee extension, occurring with the greatest knee-to-knee separation may cause overload to the hip adductor of an athlete’s drive leg that can be intensified with hip adductor weakness.

This week’s ACIQ and blog go into deeper detail about how hip adductor strains occur, current injury relationships to the throwing arm, and the preventative training necessary to reduce risk.  Future biomechanical research should look at the interconnection between ground reaction force applications and frontal plane hip mechanics to determine athletes who could be at risk. 

In all cases, athletes and coaches should be monitoring arm strength and range of motion to optimize the throwing arm for health and velocity.  Any inefficiency with the lower body will impact the throwing arm, so it’s important that we focus on monitoring throwing arm strength, as changes in lower body fatigue will have less of an impact on biomechanical compensations and loading increases on the throwing shoulder and elbow.  As always strength matters most, so ensure you have no weak links from the ground up, and if you do experience a lower-body injury, use our platform to ensure a safe return to competition as you build up throwing workload.

Have a great week!

Train hard,

Ryan