Low Dose Resistance Exercise: A Pilot Study Examining Effects on Blood Pressure and Augmentation Index Between Intensities

Dynamic resistance exercise-induced pressor response does not alter hypercapnia-induced cerebral vasodilation in young adults

Excessive arterial pressure elevation induced by resistance exercise (RE) attenuates peripheral vasodilatory function, but its effect on cerebrovascular function is unknown. We aimed to evaluate the effect of different pressor responses to RE on hypercapnia-induced vasodilation of the internal carotid artery (ICA), an index of cerebrovascular function. To manipulate pressor responses to RE, 15 healthy young adults (11M/4F) performed two RE: high intensity with low repetitions (HL) and low intensity with high repetitions (LH) dynamic knee extension. ICA dilation, induced by 3 min of hypercapnia, was measured before and 10 min after RE using Doppler ultrasound. HL exercise elicited a greater pressor response than LH exercise. In relaxation phases of RE, ICA blood velocity increased in both HL and LH trials. However, ICA shear rate did not significantly increase in either trial (P = 0.06). Consequently, neither exercise altered post-exercise hypercapnia-induced ICA dilation (HL, 3.9 ± 1.9% to 5.1 ± 1.7%; LH, 4.6 ± 1.4% to 4.8 ± 1.8%; P > 0.05 for all). When viewed individually, the changes in ICA shear rate were positively correlated with changes in end-tidal partial pressure of carbon dioxide (P_ETCO₂) (r = 0.46, P < 0.01) than with mean arterial pressure (r = 0.32, P = 0.02). These findings suggest that the effects of RE-induced pressor response on cerebrovascular function may be different from peripheral arteries. An increase in P_ETCO₂ during the relaxation phase may play a more crucial role than elevated pressure in increasing cerebral shear during dynamic RE.

High-intensity functional exercise does not cause persistent elevations in augmentation index in young men and women

Elevations in central augmentation index (AIx) are predictive of cardiovascular disease. Our objective was to examine AIx immediately and 24-hrs following an acute bout of high-intensity functional training (HIFT) in apparently healthy young adults. A second aim compared the exercise induced AIx recovery response between men and women. Thirty-two recreationally active younger adults (n=16 men) were tested. Baseline central hemodynamic measures were assessed, followed by a single bout of bodyweight HIFT. The HIFT included four rounds of burpees, jump squats, split squats, and walking lunges. Assessments were repeated 5-, 10-, 15- and 24-hrs post exercise. AIx was normalized to a heart rate of 75 bpm (AIx75). There was a significant main effect of time on AIx75 across all groups (p<0.001) with AIx75 increasing at all acute timepoints compared with baseline and returning to resting values 24-hrs post-exercise. When examining sex differences after covarying for height and body fat percentage, we found no time*sex interaction (p=0.62), or main effect for sex (p=0.41), but the significant main effect of time remained (p<0.001). The AIx75 response to HIFT follows a similar recovery pattern as previously studied modes of exercise with no residual effects 24 hrs later and no differences between men and women indicating no persistent cardiovascular strain in younger adults participating in this mode of exercise.

The Effect of a Single Bout of Resistance Exercise with Blood Flow Restriction on Arterial Stiffness in Older People with Slow Gait Speed: A Pilot Randomized Study

Purpose: Low-intensity resistance exercise with moderate blood-flow restriction (LIRE-BFR) is a new trending form of exercises worldwide. The purpose of this study was to compare the acute effect of a single bout of traditional resistance exercise (TRE) and LIRE-BFR on arterial stiffness in older people with slow gait speeds. Methods: This was a randomized, controlled clinical study. Seventeen older adults (3 men; 14 women; 82 ± 5 years old) completed a session of TRE (n = 7) or LIRE-BFR (n = 10). At baseline and after 60 min post-exercise, participants were subject to blood pressure measurement, heart rate measurements and a determination of arterial stiffness parameters. Results: There was no significant difference between the TRE and LIRE-BFR group at baseline. Pulse-wave velocity increased in both groups (p < 0.05) post-exercise with no between-group differences. Both exercise modalities did not produce any adverse events. The increase in systolic blood pressure, pulse pressure, augmentation pressure and pulse wave velocity (all p > 0.05) were similar after both TRE and LIRE-BFR. Conclusion: TRE and LIRE-BFR had similar responses regarding hemodynamic parameters and pulse-wave velocity in older people with slow gait speed. Long-term studies should assess the cardiovascular risk and safety of LIRE-BFR training in this population.