High-Intensity Interval Training and Performance
Condition: Healthy
Study type: Interventional

Summary: 
      The goal of this clinical trial was to compare to different types of high-intensity interval
      training in young, healthy females. The main questions were: Will changes in body composition
      differ between the two interventions? Will changes in endurance and muscle performance differ
      between the two interventions? Participants were randomized to 8 weeks of high-intensity
      interval training involving body weight, plyometric exercises or cycling only. Researchers
      compared changes in endurance performance, body composition, and muscle performance to
      determine if there were differences between groups.
    

Detailed description: 
      The purpose of this study was to compare the effects of plyometric- and cycle-oriented
      high-intensity interval training on body composition, aerobic capacity, and skeletal muscle
      size, quality, and function in recreationally trained females. Young (21.7 ± 3.1 yrs),
      recreationally active females were randomly assigned to 8 weeks of twice weekly plyometric (n
      = 15) or cycling (n = 15) high-intensity interval training. The plyometric-oriented Les Mills
      BODYATTACK program was used for the plyometric group whereas Les Mills SPRINT, which
      exclusively involves stationary cycling, represented the cycling group. Both protocols
      involved alternating high-intensity and recovery intervals, and participants were
      consistently instructed to give maximal effort during the 'work' periods.

      The 30 min plyometric routines included four blocks of high-intensity exercise intervals. The
      'work' portions consisted of the following exercises: high-knee runs, plyometric lunges,
      jumping jacks, squat jumps, burpees, and speed-agility patterns. The recovery periods
      consisted of complete rest (transitioning between exercises), a light jog, or a low impact
      stepping motion. On average, participants were instructed to give maximal effort for 1-2 min,
      with recovery intervals of 15-45 sec. Four separate routines were used throughout the
      duration of the study, keeping one routine per week; participants completed each routine a
      total of 4 times within a session.

      The 30 min cycling routines were performed on upright stationary bikes (Schwinn, AC
      Performance, Chicago, IL). Protocols involved 'work' ranging from 20-80 sec with recovery
      intervals between 10-60 sec. Recovery intervals consisted of complete rest on bike or
      particularly slow cycling. Resistance and cycling speed were relatively variable across
      sessions, with some intervals of higher resistance and lower speed and others involving lower
      resistance and higher speed (e.g., >120 RPMs). The same four workouts were used throughout
      the duration of the study alternating each week.

      Body composition (4-compartment model), VO2peak, countermovement jump performance, muscle
      size and echo intensity (muscle quality) as well as strength and power of the knee extensors
      and plantar flexors were measured before and after training. Body composition testing was
      completing using dual-energy x-ray absorpiometry, air displacement plethysmogrphay, and
      bioeletrical impedance. VO2peak was measured using a standardized maximal exercise test on a
      treadmill. Countermovement jump height and power was recorded with participants performing
      jumps on a force plate. Muscle size and quality were determined using non-invasive
      ultrasonography. Finally, serum growth hormone responses to the VO2peak test were measured
      before and after the protocols.
    

Intervention name(s): High-Intensity Interval Training
Intervention type(s): Behavioral
Intervention description(s): The training intervention is a popular exercise format that consist of alternating brief bouts of high-intensity efforts with bouts of light effort or complete rest.
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: Two groups performed different types of high-intensity interval training
Masking: None (Open Label)
Primary purpose: Other