Sex differences in the fatigability of arm muscles depends on absolute force during isometric contractions

Abstract

Women are capable of longer endurance times compared with men for contractions performed at low to moderate intensities. The purpose of the study was 1) to determine the relation between the absolute target force and endurance time for a submaximal isometric contraction and 2) to compare the pressor response and muscle activation patterns of men [26.3 +/- 1.1 (SE) yr] and women (27.5 +/- 2.3 yr) during a fatiguing contraction performed with the elbow flexor muscles. Maximal voluntary contraction (MVC) force was greater for men (393 +/- 23 vs. 177 +/- 7 N), which meant that the average target force (20% of MVC) was greater for men (79.7 +/- 6.5 vs. 36.7 +/- 2.0 N). The endurance time for the fatiguing contractions was 118% longer for women (1,806 +/- 239 vs. 829 +/- 94 s). The average of the rectified electromyogram (%MVC) for the elbow flexor muscles at exhaustion was similar for men (31 +/- 2%) and women (30 +/- 2%). In contrast, the heart rate and mean arterial pressure (MAP) were less at exhaustion for women (94 +/- 6 vs. 111 +/- 7 beats/min and 121 +/- 5 vs. 150 +/- 6 mmHg, respectively). The target force and change in MAP during the fatiguing contraction were exponentially related to endurance time (r(2) = 0.68 and r(2) = 0.64, respectively), whereas the change in MAP was linearly related to target force (r(2) = 0.51). The difference in fatigability of men and women when performing a submaximal contraction was related to the absolute contraction intensity and was limited by mechanisms that were distal to the activation of muscle.

Sex Differences in Arm Muscle Fatigability With Cognitive Demand in Older Adults

“…The greater fatigability when high CD was imposed during the isometric sustained contractions in young adults was associated with baseline strength [16] such that weaker individuals were more susceptible to increased fatigability, possibly as a result of altered muscle perfusion [11,12,16]. This was achieved because we were able to match some of the male and female cohort for strength [16].…”

Comparison of neuromuscular adjustments associated with sustained isometric contractions of four different muscle groups

“…TIME TO TASK FAILURE of a sustained submaximal isometric contraction (i.e., endurance time, ET) depends on physiological factors such as relative force level (30,35), muscle fiber type composition (16,51,77), muscular activation strategy (6,19,38), muscle size (36), and length (54,58) but also depends on psychological factors such as motivation, mood, and expectation (24). Whereas the task dependency of ET is well documented (23,25,26), little is known about muscle fatigue characteristics induced by a given task sustained until failure in different muscle groups, in the same individuals.…”

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

“…The gender difference in muscle endurance is believed to be related to factors such as muscle mass, energy metabolism, and muscular tissue (Hicks et al 2001). Hunter and Enoka (2001) suggested that because people with larger muscle strength must maintain larger, absolute muscle strength when using the fixed, relative demand value, they are judged to be inferior in muscle endurance. Even when performing work with the same relative intensity, males exert larger muscle forces than females.…”