Sex differences in muscle contraction-induced limb blood flow limitations

• Published in: European journal of applied physiology Vol. 124; no. 4; pp. 1121 - 1129
• Main Authors: Hammer, Shane M., Sears, Kylie N., Montgomery, Tony R., Olmos, Alex A., Hill, Ethan C., Trevino, Michael A., Dinyer-McNeely, Taylor K.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-04-2024; Springer Nature B.V
• Subjects: Biomedical and Life Sciences; Biomedicine; Blood flow; Doppler effect; Females; Gender differences; Human Physiology; Males; Muscle contraction; Occupational Medicine/Industrial Medicine; Original Article; Sex differences; Sports Medicine; Intramuscular pressure; Sex differences; Fatigability; Blood flow
• ISSN: 1439-6319; 1439-6327
• DOI: 10.1007/s00421-023-05339-5

Purpose
To determined sex differences in absolute- and %-reductions in blood flow during intermittent muscular contractions as well as relationships between blood flow reductions and time to task failure (TTF).
Methods
Thirteen males (25 ± 4 years) and 13 females (22 ± 5 years) completed intermittent isometric trapezoidal forearm flexion at 50% maximal voluntary contraction until task failure. Doppler ultrasound was used to measure brachial artery blood flow (BABF) during the 12-s plateau phase and 12-s relaxation phase.
Results
Target torque was less in females than males (24 ± 5 vs. 42 ± 7 Nm;
p
 < 0.001); however, TTF was not different between sexes (F: 425 ± 187 vs. M: 401 ± 158 s;
p
 = 0.72). Relaxation-phase BABF at end-exercise was less in females than males (435 ± 161 vs. 937 ± 281 mL/min;
p
 < 0.001) but contraction-phase BABF was not different (127 ± 46 vs. 190 ± 99 mL/min;
p
 = 0.42). Absolute- and %-reductions in BABF by contraction were less in females than males (309 ± 146 vs. 747 ± 210 mL/min and 69 ± 10 vs. 80% ± 6%, respectively; both
p
 < 0.01) and were associated with target torque independent of sex (
r
 = 0.78 and 0.56, respectively; both
p
 < 0.01). Absolute BABF reduction per target torque (mL/min/Nm) and TTF were positively associated in males (
r
 = 0.60;
p
 = 0.031) but negatively associated in females (
r
 = − 0.61;
p
 = 0.029).
Conclusions
This study provides evidence that females incur less proportional reduction in limb blood flow from muscular contraction than males at a matched relative intensity suggesting females may maintain higher levels of muscle oxygen delivery and metabolite removal than males across the contraction–relaxation cycle of intermittent exercise.