Acute effects of high-intensity dumbbell exercise after isokinetic eccentric damage: interaction between altered pain perception and fatigue on static and dynamic muscle performance

This study aimed to determine whether high-intensity dumbbell exercise involving both concentric and eccentric contractions would provide a temporary alleviation of delayed-onset muscle soreness (DOMS). It also examined the effect of alleviated muscle soreness on dynamic muscle performance using a stretch-shortening cycle (SSC; peak angular acceleration and velocity of the elbow during both lowering and concentric phases) to provide indirect evidence that DOMS contributes to the dynamic performance decrement after eccentric injury. Thirteen untrained adults performed 30 maximal isokinetic eccentric contractions of the elbow flexors to induce eccentric damage. Five sets of arm curls using a dumbbell (equivalent to 70% of isometric maximal voluntary contraction) were then performed until failure on days 1, 2, 3, and 5 of recovery. Muscle soreness significantly decreased after each session of dumbbell exercise (p = 0.001). Isometric strength further decreased immediately after dumbbell exercise, indicating muscle fatigue (p < 0.001). Dynamic performance variables were less affected by fatigue, however, with performance being reduced only for peak lowering velocity (p < 0.001). Other measures of dynamic performance were relatively constant after dumbbell exercise, particularly on days 2 and 3 when soreness was greatest. It was concluded that high-intensity concentric/eccentric dumbbell exercise was able to temporarily alleviate DOMS and that this reduction in soreness served to counter the effect of peripheral muscle fatigue during dynamic activities. Practical applications of this study are that after eccentric damage, alleviation of muscle soreness through an optimal warm-up may be helpful to temporarily recover dynamic muscle performance. Free-weight loading is one suggested technique to temporarily manage DOMS. KEY WORDS exercise-induced analgesia, DOMS, isometric strength, stretch-shortening cycle