Lower Extremity Joint Work During Braking Phase Of The Triple Hop For Distance

Abstract

The triple hop for distance (THD) involves three consecutive single leg hops for maximal horizontal displacement. This task imposes variable mechanical demands challenging balance, coordination and leg strength. While THD is common during late-stage rehabilitation, these demands may also qualify THD as appropriate for healthy athletes. While research shows that energy absorption strategies vary between landing styles, genders and heights, a limitation is the use of a single contact for analysis or training. As a result, changes in landing strategy over repeated landings are not well understood. PURPOSE: To determine changes in sagittal plane joint energetic landing strategy during each contact of THD. METHODS: Nine female college soccer players performed THD on the dominant limb. Ground reaction forces and lower extremity kinematics were measured using a force platform (1200Hz) and 9-camera motion capture system (240Hz). Three trials were collected of each contact in the THD sequence. Negative joint work was calculated as negative joint power integrated with respect to time. Total negative joint work (TJW) is the sum of eccentric work done on the hip, knee, and ankle, and the proportion of TJW done on each joint was defined as relative negative joint work (RJW). RESULTS: TJW increased from the first (-80.5 ± 26.3J) to the second (-95.5 ± 33.7J), and third (-145.2 ± 42.5J) landings. From the first to second contacts, RJW done on the ankle (33.5% vs 34.7%, d = 0.10), knee (53.9% vs 52.1%, d = 0.20), and hip (12.6% vs 13.1%, d = 0.08) was unchanged. From the second to third contacts, RJW done on the ankle was substantially decreased (34.7% vs 18.4%, d = 1.67), while RJW done on the hip was substantially increased (13.1% vs 25.4%, d = 1.68). RJW done on the knee was modestly greater (52.1% vs 56.3%, d = 0.54) in the second compared to third contacts in THD sequence. CONCLUSION: The serial nature of THD requires athletes to adapt to different demands in each ground contact. This includes progressively greater braking forces and landing strategy modulation during each contact. This represents a task which exposes athletes to variable demands of both ground reaction forces and joint work in a controlled manner. THD may therefore address multiple athletic performance qualities during performance enhancement and rehabilitation.