Exhausting stretch-shortening cycle (SSC) exercise causes greater impairment in SSC performance than in pure concentric performance

Abstract

The purpose of the present study was to investigate the fatigue effect of repeated exhaustive stretch-shortening cycle (SSC) exercise on concentric muscle function. Ten healthy male subjects performed SSC exercise [92 (30) jumps] on a special sledge apparatus. Exhaustion occurred on average within 3 min. A squat jump (SJ) test utilizing a concentric-only action was performed immediately before and after the SSC exercise, and then 10 min, 20 min, 2 days and 4 days later. In addition, a drop jump (DJ) test using an SSC was also performed immediately before and 20 min after the SSC exercise, and 2 days and 4 days later. During jump tests, lower limb joint moment, power, and work contributions were analyzed by using the kinetic and kinematic data. The fatigue exercise was characterized by a relatively high blood lactate concentration [7.2 (0.8) mmol x l(-1)] and a 2-day delayed increase in serum creatine kinase activity [486 (300) U x l(-1)]. SJ performance decreased markedly immediately after the SSC exercise (P<0.05) and then recovered within 10 min. In contrast, DJ performance and knee joint contribution showed a delayed decrease 2 days after the SSC exercise bout. The surface electromyographic (EMG) activity of the lower limb muscles showed no obvious change in the SJ in comparison to the DJ, although in the latter there was a delayed decrease of knee extensor EMG during the pre-activation and braking phases. The results suggest that isolated concentric muscle function is affected mainly by acute metabolic fatigue after SSC exercise. During a follow-up period after the exercise, changes in hip and knee joint contribution in SJ showed a different recovery pattern compared to those in eccentric DJ. It could be suggested that exhaustive SSC exercise would mainly influence the relative power-work balance between the hip and knee joints during the eccentric phase of SSC. Thus different motor control strategies may account for the distinctive fatigue responses observed in SJ and DJ.

An Investigation Into the Recovery Process of a Maximum Stretch-Shortening Cycle Fatigue Protocol on Drop and Rebound Jumps

“…Similar findings have been reported for fatigue studies that used a submaximal SSC intensity workout. Avela and Komi (4), Gollhoffer et al (20,19), and Horita et al (25) reported a reduction in CT postfatigue. Avela and Komi (4), Hortia et al (26,27), and Nicol and Komi (33) indicated that because of submaximal SSC fatigue, the muscle mechanics and joint and muscle stiffness control are hampered.…”

“…Horita et al (27) reported an early recovery 2 hours postfatigue, but no potentiation effect was reported for the DJ. Horita et al (25) again examined the effect of a repeated exhaustive submaximal SSC fatigue protocol on DJs that were performed 20 minutes and 2 and 4 days after the workout. No potentiation effect was reported by the authors.…”

“…A possible reason for the lack of a PAP effect in past SSC fatigue studies may be because of a submaximal intensity SSC fatigue workout being used. For example, Horita et al (25) required subjects to perform repeated RBJs on the sledge and force platform apparatus to a height representing 70% of their predetermined maximum. In contrast, the present fatigue protocol probably provided greater stimulus resulting in a potentiation effect after 300 seconds because of using a 90% level for the repeated RBJs.…”

“…These and other research studies examining SSC fatigue in long distance running (29), have indicated that longer duration of fatiguing exercise often results in a reversible muscle damage process, which has considerable influence on muscle mechanisms, stretch reflex sensitivity (29), and joint and muscle stiffness (21). Various studies (19,20,25,27,30) induced fatigue by repeated submaximal SSC movements to exhaustion on a sledge and force platform ergometer and found that fatigue caused immediate reductions in SSC performance or longer term losses because of muscle damage.…”

Respostas neuromusculares dos membros inferiores durante protocolo intermitente de saltos verticais em voleibolistas

“…Entretanto, nossos resultados demonstram que durante um protocolo mais próximo da situação real de jogo, as alterações no comportamento neuromuscular, representadas pelas variáveis EMG, não foram significantes do início ao fim do protocolo. A divergência entre respostas neuromusculares pode estar relacionada com o menor efeito nos componentes contráteis e elásticos que potencializam o desempenho quando o protocolo é intermitente, como já citado na literatura (HORITA et al, 2002). Nessa perspectiva, a maioria dos estudos consideram somente as perspectivas neuromusculares e bioenergéticas ao avaliar a causa e o processo de instalação de fadiga na ação do salto vertical, induzidos pelos efeitos de protocolos contínuos e exaustivos (Bosco et al, 1986;Horita et al, 1996;Strojnik;Komi, 2000;Rodacki;Fowler;Bennett, 2002;McCaulley et al, 2007), diferentes da situação real de jogo.…”