Gaesser, Glenn A.

ABSTRACT Purpose We assessed resting central/peripheral blood pressure (BP), postexercise BP, and hemodynamic responses (stroke volume, cardiac output, and systemic vascular resistance) after acute exercise and 2 wk of aerobic training in lean and centrally obese men matched for BP. Methods Eight lean (body mass index < 25 kg·m −2 , visceral fat = 279 ± 224 cm 3 ) and eight centrally obese (body mass index > 30 kg·m −2 , visceral fat = 1471 ± 374 cm 3 ) men performed six training sessions (3 d·wk −1 for 40 min at 65%–70% HR max ). Resting BP and hemodynamic measurements were obtained at baseline, after exercise for 60 min, and at 24 h and 48 h after the last training session. Results Postexercise brachial and central systolic BP (SBP) and mean arterial BP decreased 3–4 mm Hg below resting in lean ( P < 0.001) and increased by 3 mm Hg in obese ( P < 0.02). Posttraining resting brachial/central SBP were reduced by 3–4 mm Hg only in lean men ( P < 0.05). Pretraining postexercise hypotension was significantly correlated with the training-induced change in resting brachial SBP at 48 h ( r = 0.58, P = 0.02), but not at 24 h ( r = 0.38, P = 0.15). Similar correlations were observed between acute reductions in central SBP and central SBP at 24 h ( r = 0.43, P = 0.09) and 48 h ( r = 0.54, P = 0.03) posttraining. Conclusions In contrast to the consistent results for lean men, postexercise hypotension was not observed in centrally obese men, and resting SBP was not reduced after a short aerobic training program. Considerable individual variation in postexercise BP response among obese men may have implications for design of exercise interventions to lower BP in these individuals.

We examined the relationship between energy expenditure (in kcal) and epinephrine (Epi), norepinephrine (NE), and growth hormone (GH) release. Ten men [age, 26 yr; height, 178 cm; weight, 81 kg; O2uptake at lactate threshold (LT), 36.3 ml · kg−1 · min−1; peak O2uptake, 49.5 ml · kg−1 · min−1] were tested on six randomly ordered occasions [control, 5 exercise: at 25 and 75% of the difference between LT and rest (0.25LT, 0.75LT), at LT, and at 25 and 75% of the difference between LT and peak (1.25LT, 1.75LT) (0900–0930)]. From 0700 to 1300, blood was sampled and assayed for GH, Epi, and NE. Carbohydrate (CHO) expenditure during exercise and fat expenditure during recovery rose proportionately to increasing exercise intensity ( P = 0.002). Fat expenditure during exercise and CHO expenditure during recovery were not affected by exercise intensity. The relationship between exercise intensity and CHO expenditure during exercise could not be explained by either Epi ( P = 1.00) or NE ( P = 0.922), whereas fat expenditure during recovery increased with Epi and GH independently of exercise intensity ( P = 0.028). When Epi and GH were regressed against fat expenditure during recovery, only GH remained statistically significant ( P < 0.05). We conclude that a positive relationship exists between exercise intensity and both CHO expenditure during exercise and fat expenditure during recovery and that the increase in fat expenditure during recovery with higher exercise intensities is related to GH release.

Abstract Aims High-intensity interval training (HIIT) improves peak oxygen uptake and left ventricular diastology in patients with heart failure with preserved ejection fraction (HFpEF). However, its effects on myocardial strain in HFpEF remain unknown. We explored the effects of HIIT and moderate-intensity aerobic continuous training (MI-ACT) on left and right ventricular strain parameters in patients with HFpEF. Furthermore, we explored their relationship with peak oxygen uptake (VO2peak). Methods and results Fifteen patients with HFpEF (age = 70 ± 8.3 years) were randomized to either: (i) HIIT (4 × 4 min, 85–90% peak heart rate, interspersed with 3 min of active recovery; n = 9) or (ii) MI-ACT (30 min at 70% peak heart rate; n = 6). Patients were trained 3 days/week for 4 weeks and underwent VO2peak testing and 2D echocardiography at baseline and after completion of the 12 sessions of supervised exercise training. Left ventricular (LV) and right ventricular (RV) average global peak systolic longitudinal strain (GLS) and peak systolic longitudinal strain rate (GSR) were quantified. Paired t-tests were used to examine within-group differences and unpaired t-tests used for between-group differences (α = 0.05). Right ventricular average global peak systolic longitudinal strain improved significantly in the HIIT group after training (pre = −18.4 ± 3.2%, post = −21.4 ± 1.7%; P = 0.02) while RV-GSR, LV-GLS, and LV-GSR did not (P &gt; 0.2). No significant improvements were observed following MI-ACT. No significant between-group differences were observed for any strain measure. ΔLV-GLS and ΔRV-GLS were modestly correlated with ΔVO2peak (r = −0.48 and r = −0.45; P = 0.1, respectively). Conclusions In patients with HFpEF, 4 weeks of HIIT significantly improved RV-GLS.

Heart failure with preserved ejection fraction (HFpEF) is a major cause of morbidity and mortality. Exercise training is an established adjuvant therapy in heart failure; however, the effects of high-intensity interval training (HIIT) in HFpEF are unknown. We compared the effects of HIIT vs. moderate-intensity aerobic continuous training (MI-ACT) on peak oxygen uptake (V̇o2peak), left ventricular diastolic dysfunction, and endothelial function in patients with HFpEF. Nineteen patients with HFpEF (age 70 ± 8.3 yr) were randomized to either HIIT (4 × 4 min at 85-90% peak heart rate, with 3 min active recovery) or MI-ACT (30 min at 70% peak heart rate). Fifteen patients completed exercise training (HIIT: n = 9; MI-ACT: n = 6). Patients trained 3 days/wk for 4 wk. Before and after training patients underwent a treadmill test for V̇o2peak determination, 2D-echocardiography for assessment of left ventricular diastolic dysfunction, and brachial artery flow-mediated dilation (FMD) for assessment of endothelial function. HIIT improved V̇o2peak (pre = 19.2 ± 5.2 ml·kg−1·min−1; post = 21.0 ± 5.2 ml·kg−1·min−1; P = 0.04) and left ventricular diastolic dysfunction grade (pre = 2.1 ± 0.3; post = 1.3 ± 0.7; P = 0.02), but FMD was unchanged (pre = 6.9 ± 3.7%; post = 7.0 ± 4.2%). No changes were observed following MI-ACT. A trend for reduced left atrial volume index was observed following HIIT compared with MI-ACT (−3.3 ± 6.6 vs. +5.8 ± 10.7 ml/m2; P = 0.06). In HFpEF patients 4 wk of HIIT significantly improved V̇o2peak and left ventricular diastolic dysfunction. HIIT may provide a more robust stimulus than MI-ACT for early exercise training adaptations in HFpEF.

Context: Obesity attenuates spontaneous GH secretion and the GH response to exercise. Obese individuals often have low fitness levels, limiting their ability to complete a typical 30-min bout of continuous exercise. An alternative regimen in obese subjects may be shorter bouts of exercise interspersed throughout the day. Objective: The objective of the study was to examine whether intermittent and continuous exercise interventions evoke similar patterns of 24-h GH secretion and whether responses are attenuated in obese subjects or affected by gender. Design: This was a repeated-measures design in which each subject served as their own control. Setting: This study was conducted at the University of Virginia General Clinical Research Center. Subjects: Subjects were healthy nonobese (n = 15) and obese (n = 14) young adults. Interventions: Subjects were studied over 24 h at the General Clinical Research Center on three occasions: control, one 30-min bout of exercise, and three 10-min bouts of exercise. Main Outcome Measures: Twenty-four hour GH secretion was measured. Results: Compared with unstimulated 24-h GH secretion, both intermittent and continuous exercise, at constant exercise intensity, resulted in severalfold elevation of 24-h integrated serum GH concentrations in young adults. Basal and pulsatile modes of GH secretion were attenuated both at rest and during exercise in obese subjects. Conclusions: The present data suggest that continuous and intermittent exercise training should be comparably effective in increasing 24-h GH secretion.