Chueh-Lung Hwang

Novel all-extremity high-intensity interval training improves aerobic fitness, cardiac function and insulin resistance in healthy older adults

Aging is associated with decreased aerobic fitness and cardiac remodeling leading to increased risk for cardiovascular disease. High-intensity interval training (HIIT) on the treadmill has been reported to be more effective in ameliorating these risk factors compared with moderate-intensity continuous training (MICT) in patients with cardiometabolic disease. In older adults, however, weight-bearing activities are frequently limited due to musculoskeletal and balance problems. The purpose of this study was to examine the feasibility and safety of non-weight-bearing all-extremity HIIT in older adults. In addition, we tested the hypothesis that all-extremity HIIT will be more effective in improving aerobic fitness, cardiac function, and metabolic risk factors compared with all-extremity MICT. Fifty-one healthy sedentary older adults (age: 65±1years) were randomized to HIIT (n=17), MICT (n=18) or non-exercise control (CONT; n=16). HIIT (4×4min 90% of peak heart rate; HRpeak) and isocaloric MICT (70% of HRpeak) were performed on a non-weight-bearing all-extremity ergometer, 4×/week for 8weeks under supervision. All-extremity HIIT was feasible in older adults and resulted in no adverse events. Aerobic fitness (peak oxygen consumption; VO2peak) and ejection fraction (echocardiography) improved by 11% (P<0.0001) and 4% (P=0.001), respectively in HIIT, while no changes were observed in MICT and CONT (P≥0.1). Greater improvements in ejection fraction were associated with greater improvements in VO2peak (r=0.57; P<0.0001). Insulin resistance (homeostatic model assessment) decreased only in HIIT by 26% (P=0.016). Diastolic function, body composition, glucose and lipids were unaffected (P≥0.1). In conclusion, all-extremity HIIT is feasible and safe in older adults. HIIT, but not MICT, improved aerobic fitness, ejection fraction, and insulin resistance.

Sex impacts the flow-mediated dilation response to acute aerobic exercise in older adults

ABSTRACT There is growing evidence of sex differences in the chronic effect of aerobic exercise on endothelial function (flow‐mediated dilation; FMD) in older adults, but whether there are sex differences also in the acute effect of aerobic exercise on FMD in older adults is unknown. The purpose of this study was to test the hypothesis that sex modulates the FMD response to acute aerobic exercise in older adults. Thirteen older men and fifteen postmenopausal women (67 ± 1 vs. 65 ± 2 years, means ± SE, P = 0.6), non‐smokers, free of major clinical disease, participated in this randomized crossover study. Brachial artery FMD was measured: 1) prior to exercise; 2) 20 min after a single bout of high‐intensity interval training (HIIT; 40 min; 4 × 4 intervals 90% peak heart rate (HRpeak)), moderate‐intensity continuous training (MICT; 47 min 70% HRpeak) and low‐intensity continuous training (LICT; 47 min 50% HRpeak) on treadmill; and 3) following 60‐min recovery from exercise. In older men, FMD was attenuated by 45% following HIIT (5.95 ± 0.85 vs. 3.27 ± 0.52%, P = 0.003) and by 37% following MICT (5.97 ± 0.87 vs. 3.73 ± 0.47%, P = 0.03; P = 0.9 for FMD response to HIIT vs. MICT) and was normalized following 60‐min recovery (P = 0.99). In postmenopausal women, FMD did not significantly change in response to HIIT (4.93 ± 0.55 vs. 6.31 ± 0.57%, P = 0.14) and MICT (5.32 ± 0.62 vs. 5.60 ± 0.68%, P = 0.99). In response to LICT, FMD did not change in postmenopausal women nor older men (5.21 ± 0.64 vs. 6.02 ± 0.73%, P = 0.7 and 5.70 ± 0.80 vs. 5.55 ± 0.67%, P = 0.99). In conclusion, sex and exercise intensity influence the FMD response to acute aerobic exercise in older adults. HighlightsSex impacts flow‐mediated dilation (FMD) response to acute aerobic exercise in aging.In older men, FMD was attenuated after a bout of high‐intensity interval training.FMD was also attenuated after a bout of moderate‐intensity continuous training.However, FMD was unchanged after a bout of low‐intensity continuous training.In postmenopausal (PM) women, FMD did not change following acute aerobic exercise.

All-extremity Exercise Training Improves Arterial Stiffness in Older Adults.

Large elastic arteries stiffen with age, which predisposes older adults to increased risk for cardiovascular disease. Aerobic exercise training is known to reduce the risk for cardiovascular disease, but the optimal exercise prescription for attenuating large elastic arterial stiffening in older adults is not known. Purpose The purpose of this randomized controlled trial was to compare the effect of all-extremity high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) on aortic pulse wave velocity (PWV) and carotid artery compliance in older adults. Methods Forty-nine sedentary older adults (age = 64 ± 1 yr), free of overt major clinical disease, were randomized to HIIT (n = 17), MICT (n = 18), or nonexercise controls (CONT; n = 14). HIIT (4 × 4 min at 90% HRpeak interspersed with 3 × 3 min active recovery at 70% HRpeak) and isocaloric MICT (70% HRpeak) were performed on an all-extremity non–weight-bearing ergometer, 4 d·wk−1 for 8 wk under supervision. Aortic (carotid to femoral PWV [cfPWV]) and common carotid artery compliance were assessed at pre- and postintervention. Results cfPWV improved by 0.5 m·s−1 in MICT (P = 0.04) but did not significantly change in HIIT and CONT (P > 0.05). Carotid artery compliance improved by 0.03 mm2·mm Hg−1 in MICT (P = 0.001), but it remained unchanged in HIIT and CONT (P > 0.05). Improvements in arterial stiffness in response to MICT were not confounded by changes in aortic or brachial blood pressure, HR, body weight, total and abdominal adiposity, blood lipids, or aerobic fitness. Conclusion All-extremity MICT, but not HIIT, improved central arterial stiffness in previously sedentary older adults free of major clinical disease. Our findings have important implications for aerobic exercise prescription in older adults.