Background: A single bout of high-intensity interval resistance training (HIIRT, aka “rest-pause” training) has been shown to increase resting energy expenditure (REE) and decrease respiratory exchange ratio, an indicator of increased fat burning. This study compared the long-term effects of HIIRT to those of traditional resistance training on body composition, lipid profile, and muscle strength.
The study: Twenty healthy adults (aged 22 on average) began the trial with the same traditional resistance training (TRT) protocol for weeks 1–2. For weeks 3–8, they were randomized into two groups: TRT (n=9) or HIIRT (n=11). The workouts were performed thrice a week with at least one day of rest in between.
The 62-minute TRT session was simple: 3 sets of 15 reps at 60% one-repetition maximum load (1RM), with 75 seconds of rest in between, for each exercise.
The 43-minute HIIRT session was more complex: 6 repetitions at 80% 1RM. Rest 20 seconds. Lift the same weight to failure (typically two more reps). Rest 20 seconds. Lift the same weight to failure (typically two more reps again). Rest 150 seconds. Repeat the whole thing again, for each exercise.
Body composition, resting energy expenditure, aerobic capacity, muscle strength, and blood measurements were taken before and after this 8-week trial.
The results: Both protocols resulted in increased strength. The HIIRT protocol also resulted in increased endurance strength (+22.1%, as measured by isometric grip strength) and lean-body mass (+2.8%). Resting energy expenditure, respiratory exchange ratio, and lipid profile did not change in either group.