Maximal voluntary contraction (MVC) using a handgrip dynamometer was assessed in seventy-two young adult males. The subjects were divided into two groups on the basis of a BMI of 18.5 kg/m2. The subjects with a BMI < 18.5 kg/m2 (n 38) were further divided into an underweight (UW; n 20) group and a chronically energy-deficient (CED; n 18) group. The CED subjects had significantly lower MVC (30.1...

It has previously been demonstrated that the maximal voluntary contraction (MVC) torque for the quadriceps femoris (QF) muscle occurs within the mid-range (i.e., 45 – 90 deg flexion) of knee range of motion (Ng, et al, 1994; Suter and Herzog, 1997; Welsch et al, 1998). Decreases in voluntary torque generation at the extremes of the functional joint range of motion (0 – 90 deg flexion) may be at...

In older adults, isometric force production is enhanced following a voluntary lengthening contraction when compared with isometric force produced at the same muscle length without a prior lengthening contraction. This phenomenon is termed residual force enhancement (RFE), and appears to be related to the age-related maintenance of eccentric (ECC) strength. However, it is unknown whether age-rel...

A reduction of blood flow to active muscle will precipitate fatigue, and sustained isometric contractions produce intramuscular and compartmental pressures that can limit flow. The present study explored how blood flow and muscle oxygenation respond to isometric contractions at low, moderate, and maximal intensities. Over two visits, 10 males (26 ± 2 yr; means ± SD) performed 1-min dorsiflexion...

The extent and characteristics of muscle fatigue of different muscle groups when subjected to a similar fatiguing task may differ. Thirteen healthy young men performed sustained contractions at 50% maximal voluntary contraction (MVC) force until task failure, with four different muscle groups, over two sessions. Per session, one upper limb and one lower limb muscle group were tested (knee exten...

This study investigated biceps brachii oxygenation and myoelectrical activity during and following maximal eccentric exercise to better understand the repeated-bout effect. Ten men performed two bouts of eccentric exercise (ECC1, ECC2), consisting of 10 sets of 6 maximal lengthening contractions of the elbow flexors separated by 4 wk. Tissue oxygenation index minimum amplitude (TOI(min)), mean ...

34 A reduction of blood flow to active muscle will precipitate fatigue and sustained isometric 35 contractions produce intramuscular and compartmental pressures which can limit flow. The 36 present study explored how blood flow and muscle oxygenation respond to isometric 37 contractions at low, moderate and maximal intensities. Over two visits, 10 males (26±2 years; 38 mean±SD) performed 1min d...

The superimposed twitch technique is frequently used to study the degree of motor unit activation during voluntary effort. This technique is one of the preferred methods to determine the activation deficit (AD) in normal, athletic, and patient populations. One of the limitations of the superimposed twitch technique is its variability under given contractile conditions. The objective of this res...

In 11 healthy volunteers, we evaluated, in a double-blind crossover study, whether the vasodilation that follows isometric contraction is mediated by prostaglandins (PGs) and/or is O2 dependent. Subjects performed isometric handgrip for 2 min at 60% maximal voluntary contraction (MVC), after pretreatment with placebo or aspirin (600 mg orally), when breathing air or 40% O2. Forearm blood flow w...

The purpose of this study was to compare fatigue and recovery of maximal voluntary torque [maximal voluntary contraction (MVC)] and muscle oxygenation after voluntary (Vol) and electrically stimulated (ES) protocols of equal torque production. On 1 day, 10 male subjects [25 yr (SD 4)] completed a Vol fatigue protocol and, on a separate day, an ES fatigue protocol of the right dorsiflexors. Each...