We examined arterial stiffness, baroreflex sensitivity (BRS), and systolic arterial pressure (SAP) variability after an acute bout of aerobic exercise compared to resistance exercise. We hypothesized that arterial stiffness would be reduced after aerobic exercise, while it would be increased after resistance exercise, and these alterations would be associated with differential changes in BRS and SAP variability. Arterial stiffness, BRS, and SAP variability were assessed before and 20 min after a bout of aerobic exercise and resistance exercise in 13 male participants. Pulse wave velocity (PWV) was used to measure central (carotid-femoral) and peripheral (femoral-dorsalis pedis) arterial stiffness. BRS was derived via the sequence technique. Spectral decomposition of beat-to-beat SAP variability was used as an estimate of sympathetic vasomotor tone. A mode-by-time interaction (p < 0.001) was detected for central PWV, due to an increase in PWV (p < 0.05) following resistance exercise and a decrease in PWV following aerobic exercise (p < 0.05). A mode-by-time interaction was also detected for peripheral PWV (p < 0.05), due to a decrease in peripheral PWV following aerobic exercise (p < 0.05) with no change following resistance exercise. BRS was significantly lower following resistance compared with aerobic exercise (p < 0.004). SAP variability increased following resistance exercise (p < 0.05) but there was no interaction. In conclusion, aerobic exercise decreased both central and peripheral arterial stiffness, while resistance exercise significantly increased central arterial stiffness only. BRS was reduced after both bouts of exercise, but significantly greater reductions were seen following resistance exercise.

Heffernan KS, Fahs CA, Shinsako KK, Jae SY, Fernhall B. Heart rate recovery and heart rate complexity following resistance exercise training and detraining in young men. Am J Physiol Heart Circ Physiol 293: H3180-H3186, 2007. First published September 21, 2007; doi:10.1152/ajpheart.00648.2007.-The purpose of this study was to examine heart rate recovery (HRR) and linear/nonlinear heart rate variability (HRV) before and after resistance training. Fourteen young men (25.0 Ϯ 1.1 yr of age) completed a crossover design consisting of a 4-wk time-control period, 6 wk of resistance training (3 days/wk), and 4 wk of detraining. Linear HRV was spectrally decomposed using an autoregressive approach. Nonlinear dynamics of heart rate complexity included sample entropy (SampEn) and LempelZiv entropy (LZEn). HRR was calculated from a graded maximal exercise test as maximal heart rate attained during the test minus heart rate at 1 min after exercise (HRR). There was no change in SampEn, LZEn, or HRR after the time-control portion of the study (P Ͼ 0.05). SampEn (P Ͻ 0.05), LZEn (P Ͻ 0.05), and HRR (P Ͻ 0.05) increased after resistance training and returned to pretraining values after detraining. There was no change in spectral measures of HRV at any time point (P Ͼ 0.05). These findings suggest that resistance exercise training increases heart rate complexity and HRR after exercise but has no effect on spectral measures of HRV in young healthy men. These autonomic changes regress shortly after cessation of training.heart rate variability; entropy; parasympathetic; autonomic LOSS OF HEART RATE variability (HRV) and slow heart rate recovery (HRR) after exercise, indexes of cardiac autonomic function, are associated with increased risk for arrhythmia and other cardiovascular morbidities and mortality (9,11,47,48,51,53). Concomitantly, increased HRV and HRR are associated with improved prognosis and lower mortality related to cardiovascular disease (11,53). Numerous studies have shown that aerobic/endurance exercise training increases HRV and HRR (13,17,25,26,31,49). Far less is known regarding the effects of resistance training on autonomically mediated beatto-beat cardiac fluctuations and postexercise HRR.Cross-sectional studies have found faster HRR after exercise in strength-trained athletes than their sedentary peers (34), suggesting faster vagal reactivation and/or faster sympathetic withdrawal. No prospective studies have examined the effect of resistance training on HRR. Moreover, the limited evaluations of cardiac autonomic modulation using HRV do not support favorable adaptations. Spectrally decomposing HRV, Cooke and Carter (12) demonstrated no change in high-frequency (HF) power after a strength-training intervention, suggesting no change in cardiac parasympathetic modulation.However, a great deal of information in the HRV signal spectra is not solely harmonic. A certain degree of randomness or irregularity exists in the system (24). As such, use of linear methods alone to analyze beat-to-beat changes in heart rate re...

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These findings suggest that physical fitness (defined here as aerobic capacity and knee extensor strength) limits the ability of adults with DS to perform functional tasks of daily living. Randomized controlled trials should be performed to test the probable causal relationship between exercises designed to improve physical fitness and functional tasks of daily living.

These findings show that progressive resistance training is an effective intervention for persons with DS to improve leg strength and stair-climbing ability.