Endurance capacity of untrained males and females in isometric and dynamic muscular contractions

Abstract

The capacity to perform isometric and dynamic muscle contractions at different forces has been measured in two separate groups of subjects: 25 men and 25 women performed sustained isometric contractions of the knee-extensor muscles of their stronger leg to fatigue, at forces corresponding to 80%, 50% and 20% of the maximum voluntary force of contraction (MVC). The second experimental model involved a bilateral elbow-flexion weight lifting exercise. Eleven women and 12 men performed repetitions at loads corresponding to 90%, 80%, 70%, 60% and 50% of maximum load (1RM), at a rate of 10 X min-1 to the point of fatigue. Males were stronger (p less than 0.001) than females in both the static (675 +/- 120 N vs 458 +/- 80 N; mean +/- SD) and dynamic (409 +/- 90 N vs 190 +/- 33 N) contractions. Isometric endurance time of the males at a force corresponding to 20% of MVC was less than that of the females (180 +/- 51 s vs 252 +/- 56 s; p less than 0.001) but there was no difference between the sexes at 50% or 80% of MVC. Similarly, when the sexes were compared using dynamic elbow-flexion exercise, the female subjects were able to perform a greater number of repetitions than males at loads of 50% (p less than 0.005), 60% (p less than 0.001) and 70% (p less than 0.025) of 1RM, but there was no difference between the sexes at loads of 80% or 90% of 1RM.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of fatigue on force fluctuations in knee extensors in young adults

“…This increase in unsteadiness has been reported in the upper extremity both during as well as after sustained contractions (Maughan et al 1986;Huang et al 2006;Contessa et al 2009) and after repetitive fatiguing tasks (Dartnall et al 2008;Dundon et al 2008). However, except for a few studies on fatigue during sustained contractions (Maughan et al 1986;Clark et al 2005), the relationship between fatigue and unsteadiness in the lower extremity, and therefore during functional activities, remains uninvestigated.…”

Amount and structure of force variability during short, ramp and sustained contractions in males and females

“…Similarly to our findings during short duration and ramp 13 contractions, the control mechanisms influencing the amount and structure of force 14 variability could be gender dependent. 15 Moreover, the lower complexity or higher predictability found in females compared with 16 males corresponding to a higher degree of regularity may not be favourable. Indeed, it 17 may not allow appropriate adaptation to changes in sensory afferent feedback and may In summary, the analysis variability of task-related and tangential forces showed that the 1 changes in the amount and structure of force variability differed with increasing 2 contraction level and increased similarly with contraction time.…”

Gender Difference in Subjective Muscle-fatigue Sensation during Sustained Muscle Force Exertion

“…This time approximately agreed with peak force time (79.0 s) in males. Maughan et al (1986) reported that muscle endurance was higher in females in loads below 70% MVC, but there is not a gender difference in loads above 80% MVC. Laforest et al (1990) reported that there were not gender differences in force values during maximal work.…”

“…Also, the differences among individuals (Yamaji et al 2002;Yamaji et al 2004) and between genders (Maughan et al 1986;Laforest et al 1990) increase during a large decrease in force, until reaching a steady state. However, because measurement of muscle endurance using a progressive workload is without precedent, the effect of decreasing force is not entirely clear.…”

“…Muscle endurance, until now, has been mainly evaluated by sustaining time or decreasing rate using fixed, relative load intensities (Maughan et al 1986;Laforest et al 1990;Clarke et al 1992;Huczel et al 1992;Larsson et al 2003). When using very large loads, the exerted force decreases markedly just after initiating force exertion, blood pressure and heart rate increase, and also the sensation of muscle pain increases (Petrofsky and Hendershot 1984).…”