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

Abstract

Purpose: Males have larger blood pressure (BP) responses to relative-intensity static handgrip exercise compared with 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, remains unknown. Methods: BP, heart rate, muscle oxygenation (near-infrared spectroscopy), and rectus femoris EMG were recorded in 28 males and 17 females during 10% and 30% MVC static (120 s) and isokinetic dynamic (180 s; 1:2 work-to-rest ratio; angular velocity, 60°•s −1 ) 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). Results: Males had larger systolic BP responses (interaction, P < 0.0001) and muscle deoxygenation (interaction, P < 0.01) than did females during 10% static exercise, with no difference in EMG (interaction, P = 0.67). Peak systolic BP was correlated with 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 = 0.48, P = 0.001; r = 0.59, P < 0.0001, respectively). Conclusions: 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 exercise BP.

Impact of muscle echo intensity on post‐exercise blood pressure response in older normotensive and hypertensive females: Pilot study

“…First, as noted above, we conducted a very short‐lasting exercise protocol, ramp‐up exercise until 50% MVC with 50% MVC static exercise (~30‐s) and five repeated MVCs (~50‐s). This protocol may be too short and/or too weak to show relationships between MVC and BP reported in a previous study (Lee, Lutz, et al, 2021). However, even with our short‐lasting exercise protocol, we could observe differences between groups for BP post‐exercise.…”

“…Differences between the exercise protocols may also explain the lack of association between BP and absolute MVC in the present study. A previous study employed 10 and 30% MVC static (120‐s) and isokinetic dynamic (180‐s; 1:2 work‐to‐rest ratio; angular velocity, 60°s −1 ) knee extensor exercise (Lee, Lutz, et al, 2021). By contrast, in the present study, the exercise was ramp‐up exercise until 50% MVC with 50% MVC static exercise (~30‐s) and five repeated MVCs (10‐s intervals between each contraction).…”

“…This may have been too small as an exercise stimulus to reveal an association between absolute MVC and the BP response to exercise. It is also important to note that we measured BP immediately after exercise, whereas previous studies measured BP during exercise (Lee, Lutz, et al, 2021;Lee, Notay, et al, 2021;Notay et al, 2018) and in post-exercise with circulatory occlusion (Lee, Notay, et al, 2021).…”

“…Recently, Lee et al and Notay et al reported that the maximal isometric strength during maximal voluntary contraction (MVC) contributes to BP responses during exercise (Lee, Lutz, et al, 2021; Lee, Notay, et al, 2021; Notay et al, 2018) and post‐exercise with circulatory occlusion in young normotensive females as well as males (Lee, Notay, et al, 2021). However, whether this is also true in older females remains unclear.…”

Trade-Off Between Maximal Power Output and Fatigue Resistance of the Knee Extensors for Older Men

“…The intramuscular pressure developed during each contraction may be relatively higher in the more powerful participants, thus leading to greater occlusion of blood flow to the working muscle group during each contraction (Kent-Braun et al, 2002;Mcphee et al, 2014). Accordingly, the oxygen delivery to the muscle group may have been impaired in the more powerful participants during the fatigue task (Kent-Braun et al, 2002;Lee et al, 2021), worsening their neuromuscular fatigue resistance. Considering that both maximal power output and neuromuscular fatigue resistance assessed under isotonic conditions are higher in young than older adults (Dalton et al, 2015(Dalton et al, , 2010, however, this mechanism cannot explain the age-related difference in neuromuscular fatigue resistance.…”