The purpose of this study was to examine the effects of 6 weeks of high intensity functional interval training (HIFIT) compared with high intensity resistance training (HIRT) on muscle strength/endurance, functional performance, and aerobic capacity, exercise confidence and level of enjoyment, as exercise interventions for promoting health among older adults.
A group randomized trial study design was implemented to complete either the HIFIT or the HIRT training program. Twenty older adults trained and completed either HIFIT (n=12, age = 62.9 ± 5.0), or HIRT (n=8, age = 61.1 ± 3.8). Following a 2 weeks adaptation phase, the participants trained for 6-weeks, 3 times per week, for 30 minutes each session. Both groups performed 6 sets of 5 minutes of combined exercise and rest periods. Three within interval movements were performed: strength, faster body weight power, and sprint like movements. The HIFIT group trained using multi-modal exercises and executed the strength, power, and sprint movements; whereas, HIRT group trained using only the strength, and power movements for whole body resistance training. Testing involved VO2max, body composition with dual energy x-ray absorptiometry, functional performance (i.e. Timed up and Go (TUG), Stair Climb Power (SCPT), 30 second Sit to Stand (STS), Fast Gait Speed (FGS), incremental shuttle walk test (ISWT)); and strength measurements such as 3 repetition maximum (RM) deadlift, 4RM bench press, and 80% of 4RM bench press endurance. Exercise confidence and enjoyment level was surveyed by answering the Exercise Self-Efficacy Scale (EXSE) and Physical Activity Enjoyment Scale (PACES) questionnaires.
Over the 6-weeks training period, both HIFIT and HIRT groups revealed significant increases in muscle strength when performing the 3RM deadlift (p=0.00) and 4RM bench press endurance (p=0.00). Strength for 4RM bench press was significantly greater in the HIRT group (p=0.03). Both groups showed notable improvements when executing the TUG (p=0.00) and the STS (p=0.04), although HIFIT demonstrated greater increase in SCPT (p=0.01). Aerobic capacities (VO2max), anaerobic threshold (AT), and respiratory compensation threshold (RCT) were measured in relation to lean mass (LM) and body weight (BW). Also, both HIFIT and HIRT group had significant increase for VO2max LM (p=0.03), AT LM (p=0.01), RCT LM (p=0.01), VO2max BW (p=0.02), AT BW (p=0.02), and RCT BW (p=0.01). There was a significant increase for lean mass (p=0.04) and decrease in fat mass (p=0.04) for both groups from pre to post-test but no between group differences. In addition, HIFIT and HIRT groups have similar level of physical activity enjoyment (Cronbach’s α = 0.97) and self-confidence feedback (80-82%), with 96% adherence. There were no significant findings for ISWT (p=0.72), and gait speed tests (FGS, p=0.34 and CGS, p=0.54).
HIFIT and HIRT interventions have similar remarkable effects on strength, body composition adaptations, aerobic capacity, functional performance, exercise efficacy, and enjoyment level over time ; however, group by time interaction revealed HIFIT had significantly greater increase in performing stair climb power test and HIRT significantly greater increase in strength for older adults.||