Abstract
IntroductionThe delay in cardiac autonomic recovery (CAR) following physical activity is associated with increased risk of cardiovascular events. Aging is a major risk factor for cardiovascular disease, and older adults have altered resting cardiac autonomic modulation than young individuals. The intensity of exercise also influences autonomic recovery in young individuals.ObjectiveTo compare the CAR following resistance exercise (RE) in young (Y) and older (O) men, using high and low intensity RE.MethodsThe two groups (Y: n=9, age=26.3±4y, BMI=22.3±1.5Kg/m2 and O: n=9, age=64.3±4y, BMI=26.2±1.8 Kg/m2) performed 4 sets of RE, using leg press equipment, until failure. Subjects performed two different protocols; RE at 80% of 1RM (RE80) and at 30% of 1RM (RE30) in a random sequence. Heart rate was measured via a heart rate monitor and CAR was obtained through heart rate variability analysis pre and 30‐min post‐RE. The change values for heart rate variability (post 30‐min – pre) were assessed by root mean square (RMSSD) of successive RR intervals (iRR), high and low frequency in normalized units (HF and LF, respectively) and analyzed by 2‐way ANOVA (group*load).ResultsThe table shows a greater reduction of iRR, RMSSD and HF and a greater increase of LF in Y compared to O. Since the total load was higher in Y compared to O in RE80 and RE30 (Y RE30: 13767 ± 4738 kg vs. O RE30: 7812 ± 2094 kg, p < 0.05, and Y RE80: 10921 ± 4201 kg vs. O RE80: 7488 ± 2040 kg, p < 0.05), we evaluated the change in heart rate variability as a function of TL. This correction eliminated differences between Y and O for iRR and RMSSD (p > 0.05), while HF and LF remained different between Y and O (p < 0.05).ConclusionY showed delayed CAR in protocols with both RE80 and RE30. The higher TL in Y did not explain the delayed CAR in this group, thus other factors are involved. It is possible the lower heart rate variability adjustments of O is associated with limiting increases in sympathetic and reductions in parasympathetic modulation during RE but this needs further investigation.Support or Funding InformationWe thanks the support of CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico), FAEPEX (Fundo de Apoio ao Ensino, à Pesquisa e Extensão da Universidade Estadual de Campinas) and CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
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