GEPrEx

Pulse Wave Reflection Responses After Aerobic Exercise with Different Volumes in Normotensive and Hypertensive Men

Guilherme Fonseca MSc, Tainah de Paula MSc, Mario F. T. Neves MD/PhD, Felipe A. Cunha PhD State University of Rio de Janeiro, RJ, Brazil.

BACKGROUND

Although aerobic exercise (AE) has been established as effective for lowering blood pressure (BP), little is known about the alterations in aortic BP and pulse wave reflection (PWR) after exercise.

PURPOSE
To investigate the acute aortic BP and PWR responses after moderate AE with different volumes in normotensive and hypertensive men.

METHODS
A total of twenty-four participants were assigned into normotensive (n = 14) and hypertensive groups (n = 10). Participants visited the laboratory on five occasions to perform: a) a pre-participation questionnaire for assessment of cardiovascular risk, BP at-office and anthropometric profile, and then 24-h ambulatory BP monitoring (ABPM) to confirm or not the diagnosis of hypertension – normotensives were defined as those with 24-h SBP/DBP < 130/80 mmHg, and hypertensives as those with 24-h SBP/DBP ≥ 130/80 mmHg groups; b)  resting and maximal oxygen uptake (VO₂) assessments; c) a non-exercise control session (CTL), and two cycling bouts at 50% VO₂ reserve (150 vs. 300 kcal) in a randomized order. Aortic SBP (aSBP), aortic pulse pressure [aPP (i.e. aSBP minus aDBP)], augmented pressure [AP (i.e. augmentation of aSBP induced by return of the reflected wave)], and augmentation index [AIx (ratio between AP vs. PP × 100 to give a percentage)] were determined using applanation tonometry 10 min before, and 30- and 70-min after CTL and the two exercise bouts in a supine position (SphygmoCor® system, AtCor Medical Pty Ltd, Sydney, Australia).

All statistical analyses were performed using Statistica 10 software (StatSoftTM, Tulsa, OK, USA). Descriptive sample statistics are reported as the mean and standard error of the mean (SEM). Changes in aortic BP and PWR were calculated as ∆ values [i.e. difference between post- and pre-intervention values]. The effects of condition and time on aortic BP and PWR responses were analyzed using a 2-way RM-ANOVA. LSD post hoc tests were applied to determine pair wise differences when significant F ratios were obtained. Two-tailed statistical significance for all tests was accepted as P ≤ 0.05.

RESULTS
In the normotensive group, AE 150 kcal decreased aSBP (mean diff: ∆ – 8.1 mmHg,  P = 0.050) and AIx (mean diff: ∆ – 10.5 %,  P = 0.036), in comparison with CTL, until 30 min of recovery. In addition, normotensive men showed a decrease in aPP after all AE bouts, without differences between conditions. In the hypertensive group, only AE 300 kcal was able to mitigate the aSBP increase observed between 30 and 70 min post-CTL (mean diff30-70min: Δ 7.0 mmHg, P = 0.017) and post-AE 150 kcal (mean diff30-70min: Δ 7.3 mmHg, P = 0.013). Like aSBP, post hoc pairwise comparisons showed a significant increase for aPP between 30 and 70 min post-CTL (mean diff30-70min: Δ 4.0 mmHg, P = 0.050), while both AE bouts attenuated the aPP increase observed in CTL .

Figure 1: Mean ± SE values for aortic BP and PWR responses in the normotensive and hypertensive groups following 30 and 70 min of recovery from CTL and each cycling bout. P values indicate significant differences between 30 and 70 min post-intervention. *: Significantly different from CTL at 30 min (P < 0.05).

KEY POINTS

• In terms of acute aortic BP and PWR responses, exercise volume is not a primary outcome of the exercise prescription in normotensive men, at least when training bouts are performed at moderate-intensity.
• Aerobic exercise performed with higher volume (e.g. 300 kcal) is recommended for individuals with hypertension. The present study provides evidence that this strategy may mitigate the increased BP responses observed after CTL and AE with lower volume (e.g. 150 kcal).
• Regardless of exercise-related energy expenditure, aerobic bouts performed at moderate-intensity do not affect the acute PWR responses among hypertensive men.
• These findings may have important implications within the context of aerobic exercise prescription for the initial management of hypertension.

CONCLUSIONS

In the normotensive group, lower AE volume was able to reduce aortic BP until 30 min of recovery. However, only the greater AE volume attenuated the increase in aortic BP, with no difference in PWR after any experimental protocol in the hypertensive group.

FUNDING
Supported by the Brazilian Council for the Technological and Research Development (CNPq) and Carlos Chagas Foundation for the Research Development in the State of Rio de Janeiro (FAPERJ).

Recovery pattern of cardiac autonomic control following aerobic exercise with different volumes in hypertensive men

André C. Michalski MSc, Guilherme Fonseca MSc, Victor Costa, Tainá Pryor, Paulo Junior Tainah  Paula PhD, and Felipe A. Cunha PhD.

State University of Rio  Janeiro, RJ, Brazil. 

BACKGROUND
The recovery pattern of cardiac autonomic control acute aerobic (AE) is a robust index of individual ability to recruit tone and may provide further evidence of the risks and benefits of a typical AE bout to promote health. However, the extent to which autonomic control, as assessed by heart rate variability (HRV), depends on exercise volume remains unclear in hypertensive individuals.

PURPOSE
The present study investigated the acute effects of cycling bouts with different volumes and matched by on HRV markers in hypertensive men.

Ten men [age: 39.0 ± 7.0 yr; body mass index: 29.3 ± 1.0  kg/m²; maximal oxygen uptake (VO_2max): 26.7 ± 0.8 mL∙kg^-1∙min^-1; 24-h ambulatory systolic/diastolic blood pressure (SBP/DBP): 139 ± 8 / 86 ± 7 visited the times to undertake the following procedures: a) assessment of resting and maximal VO₂; b) perform a non-exercise control session (CTL) and two AE bouts expending 150 (AE150) and 300 (AE300) at 50% VO₂ , order. The root mean square of successive R-R differences calculated for consecutive 30-s windows (rMSSD30s) was calculated to assess the reactivation during the first 5 min of recovery in a supine position via (RS800cx, Polar^TM, Finland). Prolonged HRV analysis [i.e. – (LF), high-frequency band (HF), and sympathovagal balance (LFHF ratio)] was performed during the subsequent 21-h under ambulatory conditions using a three-channel Holter (CardioLight, Cardios Ltda, Brazil). 

All statistical analyses were performed using IBM SPSS® version 23 (SPSS^TM Inc., Chicago, IL USA). Marginal models were used to compare HRV changes between trials. Where main effects were statistically significant, post hoc pairwise comparisons with Sidak-adjusted P values were performed. Statistical significance was accepted as P ≤ 0.05.
RESULTS

Mean (SD) times to achieve 150 and 300 at 50% VO₂R were 22.1 (3.6) and 44.3 (6.2) min, respectively. Significant differences for rMSSD30s were only detected between CTL vs. AE150 [∆ -38.8 ms (P < 0.001)] and CTL vs. AE300 [∆ – 40.0 (P < 0.001)]. Within the subsequent 21-h of recovery, no significant differences were observed among CTL, AE150 and AE300 for LF, HF and LFHF ratio.

 

These findings suggest that exercise volume is not a major determinant of exercise prescription when considering the recovery pattern of cardiac autonomic control in hypertensive men, at least when AE is performed at

FUNDING
Supported by the Brazilian Council for the Technological and Research Development (CNPq) and Carlos Chagas Foundation for the Research Development in the State of Rio de Janeiro (FAPERJ).