Sex Differences in Muscle Metaboreflex Activation after Static Handgrip Exercise

Abstract

PurposeLarger blood pressure (BP) responses to relative-intensity static exercise in men versus women are thought to involve altered muscle metaboreflex activation, but whether this is because of an intrinsic sex difference in metabolite production or differences in muscle strength and absolute load is unknown.MethodsContinuous BP and heart rate were recorded in 200 healthy young men and women (women: n = 109) during 2 min of static handgrip exercise at 30% of maximal voluntary contraction (MVC), followed by 2 min of postexercise circulatory occlusion (PECO). Muscle sympathetic nerve activity (MSNA) was recorded in a subset of participants (n = 39; women, n = 21), permitting calculation of signal-averaged resting sympathetic transduction (MSNA-diastolic BP). Sex differences were examined with and without statistical adjustment for MVC. Multivariate regression analyses were performed to identify predictors of BP responses.ResultsMen had larger systolic BP responses (interactions, P < 0.0001) to static handgrip exercise (24 ± 10 vs 17 ± 9 mm Hg [mean ± SD], P < 0.0001) and PECO (20 ± 11 vs 16 ± 9 mm Hg, P < 0.0001). Adjustment for MVC abolished these sex differences in BP (interactions, P > 0.7). In the subset with MSNA, neither burst frequency or incidence responses to static handgrip exercise or PECO differed between men and women (interactions, P > 0.2). Resting sympathetic transduction was also similar (P = 0.8). Multiple linear regression analysis showed that MVC or the change in MSNA, were predictors of BP responses to static handgrip, but only MVC was associated with BP responses during PECO.ConclusionsSex differences in absolute contraction load contribute to differences in BP responses during muscle metaboreflex isolation using PECO. These data do not support an intrinsic effect of sex as being responsible for exercise BP differences between men and women.

Sympathoexcitatory Responses to Isometric Handgrip Exercise Are Associated With White Matter Hyperintensities in Middle-Aged and Older Adults

“…We have previously reported a 10-14% increase in HR, 7-20% increase in MAP, and 9-13% increase in MCAv in response to IHG exercise at 30% of MVC until fatigue in postmenopausal women with or without a history of hypertensive pregnancy ( Ranadive et al, 2017 ; Miller et al, 2019 ). Consistent with our previous work and others, we observed similar sustained increases in cardiovascular ( Lewis et al, 1983 ; Sander et al, 2010 ; Ranadive et al, 2017 ; Lee et al, 2021 ) and cerebrovascular variables ( Miller et al, 2019 ) during IHG exercise and post-exercise ischemia. A unique aspect of this study is the inclusion of cerebral hemodynamics (MCAv and CVRi) to assist in interpretation of hemodynamic changes in the cerebral vessels in response to two sympathoexcitatory stressors.…”

“…our previous work and others, we observed similar sustained increases in cardiovascular (Lewis et al, 1983;Sander et al, 2010;Ranadive et al, 2017;Lee et al, 2021) and cerebrovascular variables (Miller et al, 2019) during IHG exercise and postexercise ischemia. A unique aspect of this study is the inclusion of cerebral hemodynamics (MCAv and CVRi) to assist in interpretation of hemodynamic changes in the cerebral vessels in response to two sympathoexcitatory stressors.…”

“…Accordingly, participants with one or more copies of the APOE ε4 allele were considered APOE ε4 positive and assigned a value of 1 while participants without a copy were considered APOE ε4 negative and assigned a value of 0 ( Kaufman et al, 2021 ). Finally, the pressor response to handgrip exercise may be dependent upon absolute contraction loads during exercise ( Lee et al, 2021 ). Therefore, work performed during the IHG exercise protocol was added as an independent variable to account for inter-individual differences in MVC and absolute contraction load during exercise.…”

Sympathetic vasomotor outflow during low‐intensity leg cycling in healthy older males

“…It has been suggested that the absolute (rather than the percentage) ΔMSNA exerts the most influence on target organ responses, and is therefore the most physiologically significant measure (Tanaka et al, 1999). All recent studies (Badrov et al, 2016;Gagnon et al, 2015;Lee et al, 2021;Miller et al, 2019;Notarius et al, 2019;Wenner et al, 2022), with the exception of Keller-Ross et al (2020), that compared MSNA responses to acute physiological stressors (i.e., handgrip exercise and cold pressings) between younger and older individuals reported absolute MSNA changes only. MSNA BF is related to the plasma noradrenaline concentration (Morlin et al, 1983;Ng et al, 1993;Wallin et al, 1987) and renal noradrenaline spillover (Wallin et al, 1996).…”

Effect of isometric handgrip exercise on cognitive function: Current evidence, methodology, and safety considerations

“…For example, Keller et al (2022) used fNIRS to assess participants’ cerebral oxygenation during IHE and observed that at a 25% MVC protocol, there was a decrease in oxyhemoglobin in males but an increase in females, which directly affects cognitive performance ( Herold et al, 2019b ; Zhu et al, 2022 ). Additionally, sex differences in matched contraction load contribute to differences in BP responses and cardiac baroreflex sensitivity ( Teixeira et al, 2018 ; Lee et al, 2021 ), which potentially indirectly affects cognitive performance ( Ogoh and Tarumi, 2019 ). Lee et al (2021) reported males having larger acute BP responses during and immediately after the 2-min with 30% MVC exercise than females.…”