Shorter 1-minute HIIT intervals significantly increased work completed to task failure (8447 kJ) compared to 3-minute intervals (1930 kJ) and constant load (1076 kJ) (P<0.001).
RCT (n=12)
Randomized
Does a shorter work-to-rest ratio HIIT protocol (1-min) improve exercise tolerance and reduce fatigability compared to longer intervals (3-min) or constant load in healthy individuals?
Shorter high-intensity cycling intervals (1-min work/rest) mitigate physiological and perceptual responses, enhancing exercise tolerance compared to longer intervals or constant load.
Absolute Event Rate: 8447% vs 1930%
p-value: p=<0.001
INTRODUCTION: The intensity, duration, and distribution of work and recovery phases during high-intensity interval training (HIIT) modulate metabolic perturbations during exercise and subsequently influence the development of performance fatigability and exercise tolerance. This study aimed to characterize neuromuscular, perceptual, and cardiorespiratory responses to work-to-rest ratio-matched HIIT protocols differing in work and rest interval duration. METHODS: Twelve healthy individuals (six women) first completed a ramp incremental test to determine 90% of peak power output, and then in three randomized visits, they completed three cycling protocols to task failure at 90% of peak power output: (i) 3- to 3-min work-to-passive rest ratio HIIT (HIIT 3min ), (ii) 1- to 1-min work-to-passive rest ratio HIIT (HIIT 1min ), and (iii) constant load (CL). Interpolated twitch technique, including maximal voluntary isometric knee extensions and femoral nerve electrical stimuli, was performed at baseline, every 6 min of work, and task failure. Perceptual and cardiorespiratory responses were recorded every 3 min and continuously across the exercises, respectively. RESULTS: The work completed during HIIT 1min (8447 ± 5124 kJ) was considerably greater than HIIT 3min (1930 ± 712 kJ) and CL (1076 ± 356) ( P < 0.001). At work-matched, HIIT 1min resulted in a lesser decline in maximal voluntary contraction and twitch force compared with HIIT 3min and CL ( P < 0.001). Perceived effort, pain, and dyspnea were least in HIIT 1min and HIIT 3min compared with CL ( P < 0.001). At task failure, HIIT 1min resulted in less voluntary activation than HIIT 3min ( P = 0.010) and CL ( P = 0.043), and engendered less twitch force decline than CL ( P = 0.021). CONCLUSIONS: Overall, the mitigated physiological and perceptual responses during shorter work periods (HIIT 1min ) enhance exercise tolerance in comparison to longer work intervals at the same intensity (HIIT 3min , CL).
McClean et al. (Mon,) conducted a rct in Healthy individuals (n=12). 1- to 1-min work-to-passive rest ratio HIIT (HIIT 1min) vs. 3- to 3-min work-to-passive rest ratio HIIT (HIIT 3min) and constant load (CL) was evaluated on Work completed to task failure (p=<0.001). Shorter 1-minute HIIT intervals significantly increased work completed to task failure (8447 kJ) compared to 3-minute intervals (1930 kJ) and constant load (1076 kJ) (P<0.001).