Author(s): VAZQUEZ, J.R., RÚA-ALONSO, M., NINE, I., FARIÑAS, J., REVUELTA-LERA, B., RIVERA-MEJÍA, S.L., IGLESIAS-SOLER, E. , Institution: UNIVERSITY OF A CORUNA, Country: SPAIN, Abstract-ID: 1712

INTRODUCTION:
Hormonal changes of menopause impact on womens health (1). Resistance training is recommended on reducing the risk of cardiovascular disease (2), but manipulation of set configuration has been found to influence the acute decrease in cardiac parasympathetic modulation (3). The aim of this study was to explore cardiac autonomic modulation and baroreflex sensitivity after resistance training sessions differing in set configuration.
METHODS:
50 physically active postmenopausal women (37 normotensive-13 hypertensive) participated in this study funded by the Spanish Ministry of Science and Innovation (PID2021-124277OB). After a medical exam and familiarization, women completed in a randomized order one control (CON) and 3 experimental sessions (4 exercises): 9 sets of 4 repetitions with 45s of inter-set rest (9S); 6 sets of 6 repetitions with 72s of rest (6S) and 4 sets of 9 repetitions with 120s of rest (4S). Before and after each session, cardiac autonomic modulation [root mean square of differences between adjacent pulse interval (RMSSD), heart rate (HR), high frequency power (HF) and sample entropy (SampEn)], baroreflex sensitivity (BRS) and its effectiveness (BEI) was evaluated at rest.
4x10ANOVA was used to analyze the effects of set configuration across time for cardiac autonomic modulation (Baseline and post-sessions: 5-10, 10-15, 15-20, 20-25, 25-30, 30-35, 35-40, 40-45, 45-50min). 4x5ANOVA was used to analyze baroreflex sensitivity (Baseline and post: 5-15, 15-25, 30-40, 40-50min).

RESULTS:
No differences between normo- and hypertensive women were observed. CON values for all parameters were greater after sessions compared to experimental sessions (regardless HR, which was lower).
ANOVA detected a main effect of session, time, and session×time interaction (p<0.05) for RMSSD, HF, HR, BRS and BEI. The decrease of RMSSD and HF after 6S and 9S was greater compared to 4S (p<0.05). Compared to baseline, RMSSD was attenuated until 15min, 25min and 30min after 4S, 6S and 9S respectively (p=0.033). HF was decreased up to 20min, 25min and 30min after 4S, 6S after 9S respectively (p=0.016). Overall, FC was greater after 9S and 6S compared to 4S, being increased until 25min after 4S and 6S and up to 35min after 9S (p<0.05). Similar values of SampEn were observed between experimental sessions, being greater in CON. BRS was attenuated until 10min after 4S, and up to 25min after 6S and 9S and BEI was decreased until 15min only after 9S (p>0.05).

CONCLUSION:
Experimental sessions produced a reduction of cardiac parasympathetic modulation and cardiac baroreflex activity, being longer sets which produced a greater drop in comparison with short sets. Results agree with previous findings in healthy young subjects (3). Short set configurations should be recommended for post-menopausal women.

REFERENCES:
1) Hulteen, et al., Int. J. Sports Med, 2023.
2) Momma, et al. Br. J. Sports Med, 2022.
3) Rúa-Alonso, et al. Eur. J. Appl. Physiol, 2020.