Blood Pressure Responses to Static and Dynamic Knee Extensor Exercise between Sexes: Role of Absolute Contraction Intensity

• Published in: Medicine and science in sports and exercise
• Main Authors: Lee, Jordan B, Lutz, William, Omazic, Lucas J, Jordan, Mitchell A, Cacoilo, Joseph, Garland, Matthew, Power, Geoffrey A, Millar, Philip J
• Format: Journal Article
• Language: English
• Published: United States 01.09.2021
• ISSN: 1530-0315
• DOI: 10.1249/mss.0000000000002648

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, P<0.01) than females during 10% static exercise, with no difference in EMG (interaction, P=0.67). Peak systolic BP was correlated to MVC (r=0.55, P=0. 0001), and adjustment for MVC abolished sex differences in systolic BP (interaction, P=0.3). BP, heart rate, muscle oxygenation/deoxygenation, and EMG responses were similar between sexes during 30% static exercise (interaction, All P>0.2), 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.