Males have larger blood pressure (BP) responses to relative intensity static handgrip exercise compared to females. Controlling for absolute load (maximal voluntary contraction [MVC]) abolishes these differences. Whether similar observations exist during large muscle mass exercise or dynamic contractions, and the mechanisms involved, remain unknown.
BP, heart rate, muscle oxygenation (near-infrared spectroscopy), and rectus femoris electromyography (EMG) were recorded in 28 males and 17 females during 10% and 30% MVC static (120s) and isokinetic dynamic (180s; 1:2 work-to-rest ratio; angular velocity: 60°/s) knee extensor exercise. Static and dynamic exercises were completed on separate visits, in a randomized order. Sex differences were examined with and without statistical adjustment of MVC (ANCOVA).
Males had larger systolic BP responses (interaction, P<0.0001) and muscle deoxygenation (interaction, P0.2), including following adjustment for MVC (All P>0.1). Males had larger systolic BP responses during dynamic exercise at 10% and 30% (interaction, Both P=0.01), which were abolished after adjustment for MVC (interaction, Both P>0.08). Systolic BP responses were correlated with absolute MVC and stroke volume responses during 10% (r=0.31, P=0.04; r=0.61, P<0.0001, respectively) and 30% (r=0.4, P=0.007; r=0.59, P<0.0001, respectively).
Absolute contraction intensity can influence systolic BP responses to 10% but not 30% MVC static, as well as 10% and 30% MVC dynamic knee extensor exercise, and should be considered in cross-sectional comparisons of BP.

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