Purpose:
Evidence has accumulated to show that BP variability (BPV) has a striking relationship with cardiovascular (CV) risk and is predictive of future CV events, independent of mean BP. Despite the mounting evidence, scant attention has been paid to the ability of treatment modalities to attenuate BPV. To the best of our knowledge, no previous study has investigated the efficacy of non-pharmacologic treatment modalities on BPV. Therefore, the purpose of our study was to investigate the effects of aerobic exercise training (AEXT) on short- and long-term BPV in non-hypertensive and hypertensive African Americans.
Methods:
We compared the effects of a 6 month AEXT intervention (3 days/week, 65% of VO
2max
, 40 min/session) on BPV in 16 non-hypertensive subjects (BP < 140/90 mmHg) and 14 hypertensive subjects (BP ≥ 140/90 mmHg or receiving antihypertensive monotherapy). Before and after AEXT, office BP was measured at 3 separate visits according to JNC7 guidelines and 24hr ambulatory BP monitoring (ABPM) was conducted. From ABPM, the standard deviation (STD), coefficient of variation (CV), and average real variability (ARV) of BP were calculated in 3 time frames (awake, sleep, and 24hr) to evaluate short-term BPV. The STD, CV, and average successive variability (ASV) of BP across 3 office visits were calculated to evaluate visit-to-visit variability, an index of long-term BPV.
Results:
In the hypertensive group, there was a significant reduction in systolic BPV (SBPV) during the awake period for STD (pre: 11.3 ± 2.3 vs. post: 10.9 ± 2.5 mmHg; p < 0.03) and CV (pre: 8.5 ± 1.4 vs. post: 7.2 ± 1.2%; p < 0.02); and during the 24hr period for STD (pre: 12.6 ± 2.0 vs. post: 10.9 ± 2.5 mmHg; p < 0.04) and CV (pre: 9.6 ± 1.3 vs. post: 8.2 ± 1.5%; p < 0.03). Visit-to-visit variability in SBP for STD (pre: 7.8 ± 6.2 vs. post: 4.8 ± 4.4 mmHg), CV (pre: 6.0 ± 4.9 vs. post: 3.6 ± 3.1%), and ASV (pre: 5.2 ± 3.9 vs. post: 3.7 ± 3.0 mmHg) were also reduced post-AEXT, but did not reach statistical significance. In the non-hypertensive group, all measures of BPV were increased post-AEXT with the increase reaching statistical significance for awake diastolic BPV (DBPV) for STD (pre: 7.2 ±1.4 vs. post: 8.3 ± 1.9 mmHg; p < 0.02), CV (pre: 9.3 ±2.1 vs. post: 10.8 ± 2.2%; p < 0.02), and ARV (pre: 6.8 ±1.3 vs. post: 7.6 ± 1.6 mmHg; p < 0.04). Between group comparisons of non-hypertensive and hypertensive groups showed significant between group differences in the magnitude of change in awake SBPV (STD and CV; p < 0.007), awake DBPV (STD; p < 0.05), 24hr SBPV (STD and CV; p < 0.02), 24hr DBPV (CV; p < 0.04), and visit-to-visit variability in SBP (STD and CV; p < 0.05).
Conclusion:
These preliminary findings provide some evidence that AEXT may reduce BPV in hypertensive African Americans, however the increase in BPV in the non-hypertensive group brings into question the potential efficacy of AEXT in the treatment of BPV. Future investigations are needed.
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