A recent study found that single-leg backward hopping is more sensitive for detecting quadricep strength deficits than forward and vertical hopping tests. The backward hopping showed better knee movements, power, and work, indicating greater sensitivity to quadricep fatigue.
"These findings help us better understand lower limb mechanics when hopping in different directions and may contribute to the development of a clinically applicable and valid strength assessment for monitoring rehabilitation progress in patients following ACLR," noted researchers.
This study included 34 injury-free recreational athletes (17 females, 17 males; mean age 22.5 years). Participants performed single leg forward, vertical, and backward hopping tasks on both legs before and after a quadriceps fatigue protocol. The fatigue protocol required participants to hold one leg at 60° of knee flexion with 50% of their 1-repetition maximum weight until exhaustion for 5 repetitions, according to results published in the Journal of Sport and Health Science.
Participants performed seven to eight practice trials for each hopping task to ensure consistent performance. Motion data were collected using eight opto-reflective cameras and a force platform. Peak joint moments, power, and work during the jumping phase were calculated and normalized by body weight and height.
Backward hopping showed the highest peak knee moments, power, and work across all conditions. Knee work decreased by up to 45% post-fatigue in backward hopping, while forward hopping saw only a 33% decrease.
Limb symmetry index decreases the most post-fatigue for backward hopping. Hip work remained similar pre- and post-fatigue, while ankle work decreased post-fatigue across all tasks.
The researchers noted several limitations, including potential central mental fatigue due to the high number of trials, and the specific nature of the fatigue protocol, which might differ from sports-specific activities. The study also used a predetermined counterbalanced order for the fatigued leg, rather than considering leg dominance.
The authors declared no conflicts of interest related to this study.