Abstract
BACKGROUND: Muscle sympathetic nerve activity (MSNA) has been shown to be a predictor of cardiovascular diseases. There are currently disputed findings regarding the effects of exercise training on MSNA at rest. Therefore, this study sought to compare MSNA in young exercise trained and sedentary adults. The purpose of this analysis was to examine associations between MSNA at baseline with VO2max in order to determine if VO2max can be a predictor of MSNA. METHODS: Forty-two young adults were evaluated including 11 resistance trained (RE: age = 24 ± 4 years; BMI = 24 ± 2 kg/m2), 18 aerobically trained (AE: age = 27 ± 5 years; BMI = 24 ± 2 kg/m2), and 13 sedentary controls (CON: age = 28 ± 5 years; BMI = 25 ± 2 kg/m2). Participants underwent a maximal exercise test to exhaustion on a cycle ergometer to measure VO2max. During a separate visit, mean arterial pressure (MAP), heart rate (HR) and MSNA were measured at rest for five minutes. MSNA was assessed using burst frequency, burst incidence, and total activity. One-way ANOVA was performed in order to assess between-group differences in MSNA. Simple linear regression was performed in order to determine the impact of VO2max on MSNA and the relationship between MAP and VO2max. RESULTS: There were significant differences in VO2max across all three groups (RE: 41.4 ± 4.6 ml/kg/min; AE: 46.2 ± 4 ml/kg/min; CON: 35.3 ± 6.7 ml/kg/min; p < 0.01) and between groups (RE vs. AE p < 0.01; RE vs. CON p < 0.02; AE vs. CON p < 0.01). There were no differences in MSNA burst frequency (RE: 15 ± 8 bursts/min; AE: 17 ± 7 bursts/min; CON: 18 ± 5 bursts/min; p = 0.57), MSNA burst incidence (RE: 36 ± 13 bursts/100 cardiac cycles; AE: 34 ± 15 bursts/cardiac cycles; CON: 30 ± 7 bursts/100 cardiac cycles; p = 0.27), and total MSNA (RE: 881 ± 684 B/min; AE: 1361 ± 1092 B/min; CON: 1031 ± 379 B/min; p = 0.29) across the three groups. There were no relationships found between VO2max and MSNA burst frequency (r = 0.23; p = 0.15), VO2max and MSNA incidence (r = 0.06; p = 0.71), or VO2max and total MSNA (r = 0.03; p = 0.89). CONCLUSION: In conclusion, these results demonstrate a disassociation between MSNA and VO2max at rest in young adults. Since this analysis was limited to resting values, future studies could examine the relationship between VO2max and MSNA as a result of an exercise training intervention. Funding: NIH HL118154, Virginia Horne Henry This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.