UNLABELLED: The reduction in heart rate (HR) during the first minute of recovery immediately after a graded maximal exercise stress test (GXT) has recently been found to be a powerful and independent predictor of cardiovascular and all-cause mortality. Reduced vagal activity has been postulated as the cause, but this has not been proven in a population with slow HR recovery (HRR). PURPOSE: To investigate autonomic contributions to HRR using time-frequency analysis in a group of individuals demonstrating slow HRR. METHODS: HRR was defined as the difference in HR between peak exercise and 1 min later; a value < or = 18 bpm was set as threshold and considered abnormal. A modified continuous wavelet transform (CWT) was used to perform time-dependent spectral analysis during the baseline steady state and the following non-steady-state conditions created by GXT. This method provides dynamic measures of low-frequency (LF) and high-frequency (HF) peaks associated with autonomic activity. Individuals (N = 20) with a previous slow HRR underwent a second GXT within 3 months after their initial test. An additional eight subjects whose first GXT disclosed normal HRR were taken as a control group. RESULTS: Seven of 20 subjects demonstrated slow HRR (14 +/- 5 bpm) on the repeat test, and 13 subjects displayed normal HRR (29 +/- 5 bpm). Subjects with slow HRR in both GXT displayed significantly (P < 0.05) lower HF and LF fluctuations during recovery than those with normal HRR. CONCLUSIONS: Attenuated HRR after GXT, assessed by CWT, is indeed associated with abnormal vagal reactivation and prolonged sympathetic stimulation after termination of maximal exercise.
UNLABELLED: The reduction in heart rate (HR) during the first minute of recovery immediately after a graded maximal exercise stress test (GXT) has recently been found to be a powerful and independent predictor of cardiovascular and all-cause mortality. Reduced vagal activity has been postulated as the cause, but this has not been proven in a population with slow HR recovery (HRR). PURPOSE: To investigate autonomic contributions to HRR using time-frequency analysis in a group of individuals demonstrating slow HRR. METHODS: HRR was defined as the difference in HR between peak exercise and 1 min later; a value < or = 18 bpm was set as threshold and considered abnormal. A modified continuous wavelet transform (CWT) was used to perform time-dependent spectral analysis during the baseline steady state and the following non-steady-state conditions created by GXT. This method provides dynamic measures of low-frequency (LF) and high-frequency (HF) peaks associated with autonomic activity. Individuals (N = 20) with a previous slow HRR underwent a second GXT within 3 months after their initial test. An additional eight subjects whose first GXT disclosed normal HRR were taken as a control group. RESULTS: Seven of 20 subjects demonstrated slow HRR (14 +/- 5 bpm) on the repeat test, and 13 subjects displayed normal HRR (29 +/- 5 bpm). Subjects with slow HRR in both GXT displayed significantly (P < 0.05) lower HF and LF fluctuations during recovery than those with normal HRR. CONCLUSIONS: Attenuated HRR after GXT, assessed by CWT, is indeed associated with abnormal vagal reactivation and prolonged sympathetic stimulation after termination of maximal exercise.
Authors: Kristin Haraldsdottir; Andrew M Watson; Arij G Beshish; Dave F Pegelow; Mari Palta; Laura H Tetri; Melissa D Brix; Ryan M Centanni; Kara N Goss; Marlowe W Eldridge Journal: Eur J Appl Physiol Date: 2019-01-11 Impact factor: 3.078
Authors: N M Pimenta; H Santa-Clara; H Cortez-Pinto; J Silva-Nunes; M da Lapa Rosado; P J Sousa; R Calé; X Melo; L B Sardinha; B Fernhall Journal: Eur J Clin Nutr Date: 2013-12-04 Impact factor: 4.016
Authors: David Hupin; Philip Sarajlic; Ashwin Venkateshvaran; Cecilia Fridén; Birgitta Nordgren; Christina H Opava; Ingrid E Lundberg; Magnus Bäck Journal: Front Med (Lausanne) Date: 2021-12-15