Acute Vascular Effects of Aquatic and Land Treadmill Exercise in Pre-Hypertensive Men
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Chronic aquatic treadmill (ATM) exercise has previously been shown to offer similar benefits in cardiovascular health as traditional land treadmill (LTM) exercise with the added benefit of reduced blood pressure (BP) reactivity and increased skeletal muscle endothelial nitric oxide synthase content. The purpose of the present study was to determine the acute vascular effects of ATM and LTM exercise on resting, post-exercise, ambulatory BP, flow-mediated dilation (FMD), plasma nitrates/nitrites (NO), and carotid-femoral pulse wave velocity (PWV) in physically untrained, pre-hypertensive men. Following BP screening and a graded exercise test, 19 subjects completed the study (32 ± 12 years, 180 ± 7 cm, 91.9 ± 24.4 kg, 38.2 ± 8.4 ml·kg^-1·min^-1, 29.5 ± 9.9 % fat, 130/78 ± 7/8 mmHg). Subjects completed 2, 3-day acute exercise sequences, one for each exercise mode with 1-2 weeks between modes. Whether subjects began with ATM or LTM was randomized and counterbalanced. Each 3-day sequence included the following: day 1 exercise, day 2 exercise, and day 3 follow-up (3F). For each exercise day the following measurements were made: pre-exercise – BP, FMD, PWV, blood; immediately post-exercise (IPE) – blood; 1-hour post-exercise – blood, FMD, PWV. BP was measured following 10-minutes of seated rest prior to exercise and every 10 minutes from 20-60 minute post-exercise. Ambulatory BP was measured following each exercise session. Day 3F involved only BP, blood, FMD, and PWV measures. A 2-way repeated measures ANOVA was the primary model of statistical analysis. The specific analyses used for each dependent variable were as follows: 1) resting BP – 2 (Mode: ATM vs. LTM) x 3 (Day: 1, 2, 3F); 2) post-exercise blood pressure change and ambulatory blood pressure – 2 (Mode) x 2 (Day); 3) FMD and PWV – 2 (Mode) x 5 (Time point: Day 1 Pre, Day 1 Post, Day 2 Pre, Day 2 Post, Day 3F); 4) change in FMD and PWV – 2 (Mode) x 3 (Time point: 1, 24, 48 hours post-exercise); 5) plasma nitrates/nitrites – 2 (Mode) x 7 (Time point: Day 1 Pre, 1 IPE, 1 1hr, Day 2 Pre, 2 IPE, 2 1hr, Day 3F); 6) plasma volume change – 2 (Mode) x 6 (Time point: Day 1 IPE, 1 1hr, Day 2 Pre, 2 IPE, 2 1hr, Day 3F). While there was a main effect for mode for resting diastolic BP (DBP) and mean arterial pressure (MAP) across the 3 days, these differences existed prior to the first exercise session. There were no differences in the reduction in resting systolic BP, DBP, and MAP (~2.5 mmHg) between modes across the 3 days. There was a main effect for day on resting DBP (Day 1: 74.2 mmHg, Day 2: 72.2 mmHg, Day 3F: 72.0 mmHg) and MAP (Day 1: 91.5 mmHg, Day 2: 90.3 mmHg, Day 3F: 89.5 mmHg), indicating a reduction in resting BP following the exercise sessions. Neither ambulatory BP (136/78 mmHg) nor post-exercise BP (~2 mmHg reduction in SBP) differed between mode or exercise day. There was a trend for a mode specific difference (p = 0.076) for a greater FMD response for ATM. FMD increased from ATM1 pre-exercise (6.5 ± 3.9%) to ATM1 1-hour post-exercise (7.4 ± 4.7%) and ATM1 24-hour post-exercise (7.4 ± 4.3%), although there were no differences in plasma nitrates/nitrites. Overall these results demonstrate that acute ATM exercise offers similar BP benefits as LTM exercise with the potential for enhanced FMD and improved endothelial function. These data support the efficacy of ATM as an exercise modality to benefit cardiovascular health and mitigate disease risk.
Joubert, Dustin Paul (2015). Acute Vascular Effects of Aquatic and Land Treadmill Exercise in Pre-Hypertensive Men. Doctoral dissertation, Texas A & M University. Available electronically from