Diabetic polyneuropathy (DPN) can cause muscle atrophy, weakness, contractile slowing, and neuromuscular transmission instability. Our objective was to assess the response of the impaired neuromuscular system of DPN in humans when stressed with a sustained maximal voluntary contraction (MVC). Baseline MVC and evoked dorsiflexor contractile properties were assessed in DPN patients (n = 10) and c...

This study aimed to compare quadriceps function (i.e. strength, endurance, central, and peripheral fatigue) of young (Young-UnTr) and middle-aged (MidAge-UnTr) untrained men and young endurance-trained men (Young-Tr). Twenty-four male subjects (eight Young-UnTr (26 4 yr), eight Young-Tr (29 3 yr), and eight MidAge-UnTr (56 4 yr) performed a maximal cycling test to assess their fitness level. On...

The maximal rate of rise in muscle force [rate of force development (RFD)] has important functional consequences as it determines the force that can be generated in the early phase of muscle contraction (0-200 ms). The present study examined the effect of resistance training on contractile RFD and efferent motor outflow ("neural drive") during maximal muscle contraction. Contractile RFD (slope ...

Changes in contractile speed and force-fusion properties were examined during repetitive isometric contractions with the knee extensors at three different target force levels. Seven healthy subjects were studied at target force levels of 30, 45, and 60% of their maximal voluntary contraction (MVC) force. Repeated 6-s contractions followed by 4-s rest were continued until exhaustion. Contractile...

Few studies have quantified lower limb muscle activity over 24 h using electromyographic signals (EMG). None have described the changes in EMG duration and intensity when data are analyzed with different thresholds. Continuous bilateral EMG recordings were made from vastus lateralis (VL) in 10 subjects (20-48 yr) for 24 h. Before and after this recording, voluntary quadriceps forces and VL EMG ...

PURPOSE The present study was designed to determine to what extent muscle damage induced by repetitive eccentric exercise with maximal voluntary effort (ECC) affects the time course of central and peripheral fatigue during sustained maximal voluntary contraction (MVC). METHODS Ten healthy male volunteers were asked to perform brief (control MVC) and sustained MVC (fatigue test of 60 s in dura...

AIM Healthy adult ageing of the human neuromuscular system is comprised of changes that include atrophy, weakness and slowed movements with reduced spinal motor neurone output expressed by lower motor unit discharge rates (MUDRs). The latter observation has been obtained mostly from hand and lower limb muscles. The purpose was to determine the extent to which elbow flexor and extensor contracti...

PURPOSE To determine the most effective electromyographic (EMG) normalization method for cycling fatigue protocols. METHODS Ten healthy subjects performed two 5-s isometric knee extension maximal voluntary contractions (MVC) at a knee joint angle of 60 degrees, two fixed cycle pedal contraction at knee joint angles of 60 degrees (60 degrees A) and 108 degrees (108 degrees A), and a dynamic si...

This study analysed the effect of different electromyographic (EMG) capture rates during maximal voluntary contraction, submaximal and maximal dynamic cycling activity on EMG amplitude and signal characteristics. Ten healthy subjects participated in this study. Peak power output (PPO) and maximal isometric force output (MVC) were measured, followed by a progressive cycle ride on a cycle ergomet...

The corticospinal system plays an important role in control of voluntary movements in primates. Recently, we demonstrated that the effectiveness of this system is depressed after maximal exercise. Because the depression was absent after antidromic activation of the motoneurons, we argued that transmission across corticospinal synapses was involved. Here, we explore the possible functional conse...