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Updated: Mar 7, 2026
A Real-World High-Intensity Interval Training Protocol for Cardiorespiratory Fitness Improvement
Published on: February 22, 2022
Muscle activation and heart rate responses to a side-step interval exercise
Robert S Thiebaud1, Takashi Abe2, Jonathan C Bravo1
1Department of Kinesiology, Texas Wesleyan University, Fort Worth, TX, USA.
Background:
The side-step test is commonly used to assess agility. Side-step interval exercise may also be a potential way to improve cardiorespiratory and muscular fitness. However, the acute heart rate and muscle activation response to this type of exercise is not well established. In addition, different tempos can influence these responses. The purpose of this study was to determine the acute heart rate and muscle activation responses of a side-step interval exercise to different exercise tempos.
Methods:
Ten participants completed a V˙O2 max test and performed a side-step interval exercise for 4 × 1 min intervals separated by 1-min rest intervals at a slow (84 bpm) and fast (112 bpm) tempo. Muscle activation of the vastus lateralis and vastus medialis and heart rate were measured during exercise.
Results:
During the slow tempo, vastus lateralis muscle activation varied from 45% to 48% of maximum muscle activation (EMGmax ) while vastus medialis muscle activation varied from 51% to 54% EMGmax . During the fast tempo, vastus lateralis muscle activation varied from 53% to 65% EMGmax while vastus medialis muscle activation varied from 64% to 76% EMGmax . Heart rates varied from 80-84% HRmax from set 1 to set 4 for the fast tempo and varied from 67% to 72% HRmax from set 1 to set 4 for the slow speeds.
Conclusion:
Exercise intensity of a side-step interval exercise reached adequate levels to suggest that it may be possible to use this type of exercise to improve cardiorespiratory and muscular fitness.
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