Sex-Specific Autonomic Responses to Acute Resistance Exercise

Abstract

Background and Objectives: Acute resistance exercise (RE) reduces vagal modulation and increases sympathovagal balance, which increases the risk for arrythmias. Few studies have examined sex differences in autonomic modulation after acute RE. The purpose of this investigation was to examine sex-specific responses to acute RE on autonomic modulation. Materials and Methods: Twenty-one resistance-trained individuals (men n = 11, women n = 10) between the ages of 19 and 25 y were analyzed for autonomic modulation in response to acute RE and a control (CON). Measures of autonomic modulation were collected at rest, 15 (R15), and 30 (R30) min following both conditions. Heart rate (HR), log transformed root mean square of successive differences (lnRMSSD), total power (lnTP), low-frequency power (lnLF), high-frequency power (lnHF), sample entropy (SampEn), and Lempel-Ziv entropy (LZEn) were measured at all time points. A three-way repeated analysis of variance (ANOVA) was used to analyze sex (men, women) across condition (RE, CON) and time (Rest, R15, R30). Results: The results are similar for all heart rate variability (HRV) variables at rest for both conditions (RE, CON). SampEn was significantly higher in men compared to women at rest for both conditions (p = 0.03), with no differences in LZEn (p > 0.05). There were no significant (p > 0.05) three-way interactions on any variables. Condition by time interactions demonstrated that both sexes increase in HR (p = 0.0001) and lnLF/HF ratio (p = 0.001), but decreases in lnRMSSD (p = 0.0001), lnTP (p < 0.0001), lnLF (p < 0.0001), lnHF (p = 0.0001), and LZEn (p = 0.009) at R15 and R30 compared to rest following acute RE and were different from CON. Condition by time interaction (p = 0.017) demonstrated that SampEn was attenuated at R15 compared to rest, and the CON, but not R30 following acute RE. Conclusion: Although SampEn is more complex at rest in men compared to women, autonomic modulation responses between sexes following acute RE appear to be similar.

Sex differences in autonomic recovery following repeated sinusoidal resistance exercise

“…Contrary to the findings of the present study, Humm et al ( 2021 ) reported similar HRV recovery profiles across sex. Notably, the weight levels used for resistance exercise in Humm et al ( 2021 ) (70% of one‐repetition maximum) were much higher than the present study (20% of bodyweight). Higher weight levels may have elicited greater BP increases and volitional fatigue, extensively stressing the ANS of participants.…”

“…This limits the generalizability and clinical utility of previous literature, given there are known chromosomal sex differences in ANS function (Koenig & Thayer, 2016 ). The research team is aware of only one study that examined sex‐specific differences in the ANS response to resistance exercise (Humm et al, 2021 ). Humm et al ( 2021 ) examined HRV acutely following resistance exercise bouts, which comprised three sets of ten repetitions (at 70% of one‐repetition maximum) for five exercises (e.g., leg press, lateral pulldown, chest press, leg curl, and leg extension).…”

“…The research team is aware of only one study that examined sex‐specific differences in the ANS response to resistance exercise (Humm et al, 2021 ). Humm et al ( 2021 ) examined HRV acutely following resistance exercise bouts, which comprised three sets of ten repetitions (at 70% of one‐repetition maximum) for five exercises (e.g., leg press, lateral pulldown, chest press, leg curl, and leg extension). Contrary to the findings of the present study, Humm et al ( 2021 ) reported similar HRV recovery profiles across sex.…”

“…Humm et al ( 2021 ) examined HRV acutely following resistance exercise bouts, which comprised three sets of ten repetitions (at 70% of one‐repetition maximum) for five exercises (e.g., leg press, lateral pulldown, chest press, leg curl, and leg extension). Contrary to the findings of the present study, Humm et al ( 2021 ) reported similar HRV recovery profiles across sex. Notably, the weight levels used for resistance exercise in Humm et al ( 2021 ) (70% of one‐repetition maximum) were much higher than the present study (20% of bodyweight).…”

“…Specifically, despite a higher resting HR, females display higher PNS sensitivity compared to males, and parallelly, males seem to be more sensitive to SNS activity despite a lower resting HR (Koenig & Thayer, 2016 ). Particular with exercise, some investigation into sex differences in ANS recovery has been completed (Humm et al, 2021 ; Kappus et al, 2015 ; Mendonca et al, 2010 ; Queiroz et al, 2013 ), although few are specific to resistance exercise (Humm et al, 2021 ) with a paucity of studies including sustained, cyclical resistance exercise (>1‐min).…”