title: Muscle activation and heart rate responses to a side-step interval exercise.
abstract: 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% EMGmaxwhile vastus medialis muscle activation varied from 64% to 76% EMGmax. Heart rates varied from 80-84% HRmaxfrom set 1 to set 4 for the fast tempo and varied from 67% to 72% HRmaxfrom set 1 to set 4 for the slow speeds.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Kinesiology, Texas Wesleyan University, Fort Worth, TX, USA.
authors.forename: Robert S
authors.initials: RS
authors.lastname: Thiebaud
authors.affiliation: Department of Sports and Life Sciences, National Institute of Fitness and Sports in Kanoya, Kagoshima, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Abe
authors.affiliation: Department of Kinesiology, Texas Wesleyan University, Fort Worth, TX, USA.
authors.forename: Jonathan C
authors.initials: JC
authors.lastname: Bravo
authors.affiliation: Department of Kinesiology, Texas Wesleyan University, Fort Worth, TX, USA.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Giovannitti
authors.affiliation: Department of Kinesiology, Texas Wesleyan University, Fort Worth, TX, USA.
authors.forename: Avery P
authors.initials: AP
authors.lastname: Sullivan
mesh_terms: D000293:Adolescent; D000328:Adult; D000072599:Cardiorespiratory Fitness; D018592:Cross-Over Studies; D004576:Electromyography; D015444:Exercise / Q000502:physiology*; D005260:Female; D006304:Health Status; D006339:Heart Rate; D000072696:High-Intensity Interval Training / Q000379:methods*; D006801:Humans; D007537:Isometric Contraction; D008297:Male; D010507:Periodicity; D052097:Quadriceps Muscle / Q000502:physiology*; D013997:Time Factors; D055815:Young Adult
keywords: acute; cardiorespiratory fitness; electromyography; high-intensity interval training; muscular fitness