(9) Comparing the Effects of High-Intensity Functional Training and Sprint-Interval Training on Cardiovascular and Performance Metrics

Purpose: To examine the effects of a 4-week HIFT vs. SIT intervention on 2-mile run time and 3-min weighted stair climber test. Methods: 12 participants (9 males: 21±2 yrs, 179.6±7 cm, 91.4±12.7 kg; 3 females: 21±4 yrs, 162.6±3.6 cm, 64.6±5.5 kg) were assigned to either HIFT (n=6) or SIT (n=6) intervention groups. During visit 1, participants completed a 3-repetition maximum (3RM) for the standing dumbbell (DB) shoulder press (HIFT group) or a Wingate to determine peak power output (PPO) (SIT group). During visits 2 (pre) and 11 (post), participants completed a 3-min stair climber test wearing a 50-lb weighted vest and timed 2-mile run. During the stair climber test, heart rate and VO₂ were continuously collected. For visits 3-10, the HIFT group performed as many rounds as possible of a 20-min circuit consisting of 10 repetitions each of: DB bench press, DB lunge, standing DB shoulder press, and DB box step-ups using 40% 3RM. Self-selected rest was provided between exercises and sets. The SIT group completed 8 rounds of 30-sec cycling sprints at 80% PPO, with 2-minutes of active recovery cycling at 10% PPO between sets. Paired samples t-tests were used to compare within-group (absolute values) changes and independent samples t-tests to determine between-group (%Δ pre- to post-intervention) changes in peak and average HR and VO₂ during the 3-min stair climber test, and 2-mile run time. Alpha was set at p< 0.05. Results: There was a decrease in average HR for the HIFT group from pre- (160±11 bpm) to post-intervention (149±7 bpm, p=0.028) and a decrease in peak HR for the SIT group from pre- (169±9 bpm) to post-intervention (162±13 bpm, p=0.012). There was no change in any other variable for the HIFT (p=0.095-0.703) or SIT (p=0.091-0.909) groups. There was no difference between the HIFT and SIT groups in the %Δ from pre- to post-intervention for peak HR, average HR, peak VO₂, average VO₂, or 2-mile run time (p=0.179-0.550). Conclusions: After 8 sessions, HIFT reduced average HR, while the SIT reduced peak HR, during the 3-min stair climber test. However, neither group showed improvements in endurance performance or oxygen consumption. Although not significant, 8 sessions of HIFT or SIT reduced 2-mile run time, as time decreased on average by 1.3 min. This suggests HIFT and SIT protocols may be efficient options to improve fitness when time is limited. Practical Applications: Lack of time is a common reason cited for not engaging in exercise training. The results of the present study suggest completing just two, 20-min high-intensity workouts per week for 4-weeks can improve fitness parameters. Therefore, coaches and practitioners can encourage individuals to implement HIFT or SIT for a time-efficient approach to enhance their cardiovascular fitness. Acknowledgements: None