Physical Activity Level Does Not Influence the Neuromuscular Fatigue in Adults

Abstract

Introduction: Fatigue during voluntary muscle contractions is a complex and multifactorial phenomenon associated with central changes and adaptations of the neuromuscular system. Objective: The purpose of this study was to evaluate the fatigue induced by intermittent successive extension of the knee between active and inactive university students. Method: Twenty healthy men (≥18 years), voluntarily participated in this study. To determine the maximum voluntary isometric contraction (MVIC) of the knee extensors muscle group, three sets of isometric contractions of knee extension were performed for five seconds with five minutes of rest between sets. The fatigue protocol consisted of 10 sets of 10 maximal concentric contractions of the extensor on the right knee, performed at 75% of MVIC with an interval of 45". Results: Significant reductions were observed (p<0.01), both in isometric strength (-34±4%) and the dynamic strength (-40 ± 3%). In addition, the slope of relationship strength x repetition was -0.79±0.07 Nm/repetitions and the magnitude of the effect reached -8.90. Conclusion: The protocol was useful to induce peripheral fatigue, although muscle strength is greater in the active group. In both isometric and dynamic action, muscle fatigue did not differ between groups.

Alterations in peak torque occur without hematological changes after muscle fatigue

“…When we refer to tension development, our data agree with the study previously published 10 by our group, demonstrating that active individuals have higher fatigue resistance than inactive individuals. Taking into account the responses of different muscle actions, our data indicate a reduction of torque capacity in both groups in eccentric and concentric action.…”

“…The International Physical Activity Questionnaire (IPAQ) -short version was used to estimate the level of physical activity conform previously publication of our group 10 . Questions were based on the level of physical activity performed weekly.…”

“…The completion of the dynamic fatigue protocol followed the model used of our group 10 . Briefly, all subjects attended the Laboratory on four occasions to perform an Isokinetic evaluation protocol using a Biodex System 3 (Biodex, Inc.,Shirley, NY).…”

“…To establish hematological changes, blood was collected with a 5 ml syringe using methodologies outlined previously 10 . Subsequently, the blood was transferred into tubes containing EDTA and kept in motion to avoid coagulation.…”