Hip Abduction Strength Contributes to Dynamic Control of the Trunk and Legs
Simple single-leg step-down test (SLSD test) can help assess hip abduction strength, enhance performance and reduce the risk of injury
A recent study by medical personnel at USC and California Angles of 180 minor league baseball players indicated that a simple screening test can be used to identify hip weakness in pitchers that could translate into altered pitching mechanics and injury1.
Methods. The researchers had 68 pitchers and 50 position players stand on one leg and slowly lower the opposite heel to the floor. Once the heel touched the ground, they slowly returned to the starting position. The test took 4 seconds; 2 sec down and 2 sec up. Video cameras and Dartfish software were used to measure 2D hip flexion, knee valgus (knee caves in or moves inward), trunk flexion, trunk lateral lean and pelvic drop angles (hip drops).
Results. There was no significant correlation between hip abduction torque and single-leg drop variables. For pitchers, however, there was a significant relationship between hip weakness and increased knee valgus in the lead leg and a significant relationship between hip weakness and increased pelvic drop in the trail leg.
Takeaway. Pitchers who lacked hip strength were unable to effectively stabilize the knee of the lead leg or hip of the trail leg. They had an unstable base from which to apply force into the ground with the drive leg and absorb force with the landing leg. Pitching with an unstable base decreases force production in the lower body. The upper body has to compensate for the loss of lower body force which, in turn, increases the stress in the shoulder and elbow joints. Previous studies indicate that pro pitchers with poor lumbopelvic control have decreased performance and lose more time due to injury.
The SLSD down test can be used to identify movement deficits that can be corrected with properly prescribed exercises. If movement deficits can be identified and addressed early, pitchers should be able to improve pitching performance and reduce the risk of injury.
Zipser, M., et. al., Hip abduction strength: Relationship to trunk and lower extremity motion during a single-leg step-down task in pro baseball players. Inter J Sports Physical Therapy. 16(2): 342-349,2021.
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Gene Coleman, Ed. D., RSCC*E, FACSM has over four decades as a head strength and conditioning coach (Astros) and strength and conditioning consultant (Rangers). He is Professor Emeritus in the Exercise and Health Sciences Program at the University of Houston – Clear Lake and Website Education Manager baseballstrength.org.