title: Novel all-extremity high-intensity interval training improves aerobic fitness, cardiac function and insulin resistance in healthy older adults.
abstract: 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.
authors.affiliation: Dept of Applied Physiology & Kinesiology, University of Florida, Gainesville, FL, United States.
authors.forename: Chueh-Lung
authors.initials: CL
authors.lastname: Hwang
authors.affiliation: Dept of Applied Physiology & Kinesiology, University of Florida, Gainesville, FL, United States.
authors.forename: Jeung-Ki
authors.initials: JK
authors.lastname: Yoo
authors.affiliation: Dept of Applied Physiology & Kinesiology, University of Florida, Gainesville, FL, United States.
authors.forename: Han-Kyul
authors.initials: HK
authors.lastname: Kim
authors.affiliation: Dept of Applied Physiology & Kinesiology, University of Florida, Gainesville, FL, United States; Division of Health and Exercise Science, Incheon National University, Incheon, Republic of Korea.
authors.forename: Moon-Hyon
authors.initials: MH
authors.lastname: Hwang
authors.affiliation: Division of Cardiovascular Medicine, University of Florida, Gainesville, FL, United States.
authors.forename: Eileen M
authors.initials: EM
authors.lastname: Handberg
authors.affiliation: Division of Cardiovascular Medicine, University of Florida, Gainesville, FL, United States.
authors.forename: John W
authors.initials: JW
authors.lastname: Petersen
authors.affiliation: Dept of Applied Physiology & Kinesiology, University of Florida, Gainesville, FL, United States. Electronic address: ddchristou@ufl.edu.
authors.forename: Demetra D
authors.initials: DD
authors.lastname: Christou
mesh_terms: D000368:Aged; D000375:Aging / Q000502:physiology*; D001823:Body Composition; D000072599:Cardiorespiratory Fitness; D005260:Female; D005431:Florida; D064368:Healthy Volunteers; D006339:Heart Rate; D000072696:High-Intensity Interval Training / Q000379:methods*; D006801:Humans; D007333:Insulin Resistance; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption; D012307:Risk Factors; D016474:Weight-Bearing
keywords: Aerobic fitness; Aging; Cardiac function; High-intensity interval training; Metabolic risk factors; Moderate-intensity continuous training