Effect of rest duration between sets on fatigue and recovery after short intense plyometric exercise.

Plyometric training is characterized by high-intensity exercise which is performed in short term efforts divided into sets. The purpose of the present study was twofold: first, to investigate the effects of three distinct plyometric exercise protocols, each with varying work-to-rest ratios, on muscle fatigue and recovery using an incline-plane training machine; and second, to assess the relationship between changes in lower limb muscle strength and power and the biochemical response to the three exercise variants employed. Forty-five adult males were randomly divided into 3 groups (n = 15) performing an exercise of 60 rebounds on an incline-plane training machine. The G0 group performed continuous exercise, while the G45 and G90 groups completed 4 sets of 15 repetitions, each set lasting 45 s with 45 s rest in G45 (work-to-rest ratio of 1:1) and 90 s rest in G90 (1:2 ratio). Changes in muscle torques of knee extensors and flexors, as well as blood lactate (LA) and ammonia levels, were assessed before and every 5 min for 30 min after completing the workout. The results showed significantly higher (p < 0.001) average power across all jumps generated during intermittent compared to continuous exercise. The greatest decrease in knee extensor strength immediately post-exercise was recorded in group G0 and the least in G90. The post-exercise time course of LA changes followed a similar pattern in all groups, while the longer the interval between sets, the faster LA returned to baseline. Intermittent exercise had a more favourable effect on muscle energy metabolism and recovery than continuous exercise, and the work-to-rest ratio of 1:2 in plyometric exercises was sufficient rest time to allow the continuation of exercise in subsequent sets at similar intensity.

Effect of concentric vs. eccentric variant of lower limbs plyometric training on biomechanical and biochemical parameters.

AbstractThe study aimed to compare the effectiveness of two variants of 4 weeks plyometric training involving jumping up (dominance of concentric muscle work, UP) and jumping down (dominance of eccentric muscle work, DOWN) the stairs. Twenty-six young men were divided into two groups: UP (n = 13) and DOWN (n = 13). Control measurements of the muscle torques, vertical jumps, and creatine kinase (CK) activity were performed every week. The training resulted in significant changes (p < 0.001) in the muscle torques of the hip extensors (Δ ≈ 20% in both groups) and plantar flexors (ΔUP = 25%, ΔDOWN = 33%), but in the muscle torques of the knee extensors a significant (p < 0.001) increase occurred only in the group jumping down the stairs (ΔDOWN ≈ 15%). Furthermore, a significant increase (p < 0.001) of the height of the vertical jump was noted in the study only in the group jumping down (ΔDOWN = 8%). Training with the dominance of eccentric work caused greater weekly changes in the activity of creatine kinase in the plasma. The study confirmed that the exercise involving jumping on the stairs is viable in plyometric training, as it is an effective means of training the strength of the muscles of the lower limbs and vertical jump height, with a greater share assigned to jumping down consecutive steps.