Lower‐body dynamic exercise reduces wave reflection in healthy young adults

Abstract

Acute lower-body dynamic (LBD) exercise decreases surrogate measures of wave reflection, such as the augmentation index. However, the augmentation index is influenced by the combined effects of wave reflection timing, magnitude and other confounding factors external to wave reflection, which make it difficult to discern the origin of changes in surrogate measures. The relative contributions of forward (Pf) and backward (Pb) pressure wave amplitudes to central pressure can be determined by wave separation analysis. Reflection magnitude (RM = Pb/Pf) and the timing of apparent wave reflection return can also be determined. We tested the hypothesis that acute LBD exercise decreases RM and reflected wave transit time (RWTT). Applanation tonometry was used to record radial artery pressure waveforms in 25 adults (24 ± 4 years of age) at baseline and during light-, moderate-and vigorous-intensity exercise.Wave separation analysis was conducted offline using a personalized physiological flow wave to determine Pf, Pb, RM and RWTT. The RM decreased during all intensities of exercise compared with baseline (all P < 0.001; baseline, 43 ± 5%; light, 33 ± 6%; moderate, 23 ± 7%; vigorous, 17 ± 5%). The reduction in RM was attributable to the combined effect of increased Pf and decreased Pb during exercise. The RWTT decreased during all intensities of exercise compared with baseline (all P < 0.04; baseline, 156 ± 17 ms; light, 144 ± 15 ms; moderate, 129 ± 16 ms; vigorous, 121 ± 17 ms).Lastly, in a stepwise multilinear regression, Pf, but not Pb and RWTT, contributed to increased central pulse pressure during LBD exercise. These data show that wave reflection decreased and that central pulse pressure is most influenced by Pf during LBD exercise.

Seated Elliptical Exercise, But Not Periodic Standing, Alleviates Sitting-Induced Changes to Arterial Wave Reflections

“…An initial sample size estimate of n = 12 was based on simulation-based power calculations (2000 simulations) for the anticipated effect of an absolute change in RM of +0.06 for prolonged sitting, +0.04 for periodic standing, and −0.02 for seated elliptical with a common standard deviation of 0.05 (Cohen's f = 0.61), yielding >80% power to detect differences between elliptical versus prolonged sitting and elliptical versus standing in a one-way repeated-measures ANOVA design with Bonferroni-Holm corrected dependent t-tests for significant main effects (22). Effect sizes were estimated from previous work with low-intensity (40% maximal heart rate) cycling (RM Δ −0.10 from rest) and with standing (RM Δ −0.12 from supine) (18,19). The standard deviation of 0.05 is based on reported values at baseline and post-intervention (e.g., lower body dynamic exercise, isometric and dynamic handgrip exercises) (19,23).…”

“…Effect sizes were estimated from previous work with low-intensity (40% maximal heart rate) cycling (RM Δ −0.10 from rest) and with standing (RM Δ −0.12 from supine) (18,19). The standard deviation of 0.05 is based on reported values at baseline and post-intervention (e.g., lower body dynamic exercise, isometric and dynamic handgrip exercises) (19,23). We recruited additional participants (n = 18) to account for data drop out, as well as to address order and carry-over effects using a balanced Latin square design.…”

“…Standing for 30 min reduces P b , P f , and RM compared with supine rest, although an exact mechanism has not been identified (18). Moreover, acute cycling at low intensities reduces RM, likely as a result of local vasodilation and reduced vascular resistance (19,20). Although the available data on wave reflections is sparse, there are clear beneficial effects of activity interruptions on other aspects of cardiovascular health.…”

Exercise as an Aging Mimetic: A New Perspective on the Mechanisms Behind Exercise as Preventive Medicine Against Age-Related Chronic Disease

“…Exercise produces a substantial blood pressure response [systolic pressures >190 mmHg in young adults ( Sabbahi et al, 2018 )] and increase in heart rate that stiffens the large arteries ( Armentano et al, 1991 ; Studinger et al, 2003 ; Townsend et al, 2015 ). Increases in large artery stiffness during exercise ( Studinger et al, 2003 ; Sharman et al, 2005 ; Pomella et al, 2018 ) are accompanied by increased forward wave energy ( Jiang et al, 1995 ; Heckmann et al, 2000 ; Stock et al, 2021 ) and decreased wave reflection ( Stock et al, 2021 ), ultimately contributing to greater pulsatile hemodynamics ( Armentano et al, 1991 ; Ogoh et al, 2005 ; Alwatban et al, 2020 ). Additionally, exercise-induced acute increases in blood pressure may transiently impair endothelial function through a combination of mechanical distension/dilation of the artery, reductions in nitric oxide bioavailability, and endothelin-1 release during exercise ( Millgård and Lind, 1998 ; Jurva et al, 2006 ; Gonzales et al, 2011 ; Morishima et al, 2020 ).…”

Relation of Aortic Waveforms with Gut Hormones following Continuous and Interval Exercise among Older Adults with Prediabetes

“…Aerobic exercise improves blood pressure (BP), lipid profiles, and inflammation, often in the absence of clinically meaningful weight loss [ 24 , 25 , 26 ]. Furthermore, acute exercise can decrease fasting AIx75 during the immediate post-exercise period [ 27 ], although some suggest the acute effect of aerobic exercise on AIx75 may last up to 24 h following the last bout [ 28 ]. Lower AIx75 following exercise may be partially attributed to the working muscles promoting reduced vascular resistance via enhancement of nitric oxide [ 29 , 30 ].…”