PMID 28381445

Research
All papers

High-intensity interval training improves performance in young and older individuals by increasing mechanical efficiency

Jabbour G, Iancu HD, Mauriège P, Joanisse DR, Martin LJ

Question

Does six weeks of short supramaximal cycling HIIT improve mechanical efficiency, peak power, energy expenditure, body composition, and VO2max in young and older sedentary adults?

Summary

Six weeks of very short cycling sprints improved peak power and mechanical efficiency in healthy sedentary young and middle-aged/older adults, but did not improve VO2max. The study had no non-exercise control group and focused on laboratory physiology outcomes.

Methodology

  • Healthy sedentary young adults and healthy sedentary older adults.
  • 30 participants.
  • Cycle ergometer.
  • Work intervals: 6 seconds supramaximal cycling.
  • Recovery: 2 minutes passive recovery.
  • Intensity: Maximal velocity against resistance determined by force-velocity testing; resistance adjusted every 2 weeks.
  • About 16-18 minutes including 5-minute warm-up at 40-50% HRmax.
  • 3 sessions per week.
  • 6 weeks; 18 sessions.
  • Single-arm pre/post training study comparing responses in young and older age groups.
  • Peak power output, Mechanical efficiency, VO2max, and Body mass and fat mass were tracked.

Outcomes

Peak power

Peak power increased in both young and older groups.

Young Pmax 520 to 620 W; older 540 to 600 W; relative Pmax increased young 6.1 to 8.5 W/kg and older 6.1 to 7.1 W/kg; p < 0.01.

Improved

Mechanical efficiency

Mechanical efficiency increased at VT1, VT2, and VO2max in both groups.

ME increases were significant at all assessed intensities (p < 0.01), with larger percentage gains in the older group at several thresholds.

Improved

VO2max

VO2max did not change in either age group.

Authors reported no VO2max change after training.

No clear change

Older group body composition

The older group lost body mass and fat mass, while the young group did not change body mass.

Older body mass 90.1 to 87.1 kg, p < 0.01; fat mass 33.8 to 31.8.

Improved

Insights

  • Very short sprints with long passive recovery can improve peak power and mechanical efficiency without increasing VO2max.
  • For app messaging, this is better evidence for performance/efficiency mechanisms than for cardiorespiratory fitness gains.
  • The 6-second sprint format is highly equipment- and testing-dependent.

Limitations

  • No non-exercise control group.
  • Small sample.
  • Short intervention.
  • The older group averaged about 54.5 years, so it is not representative of elderly adults.
  • Laboratory cycle ergometry and mechanical-efficiency outcomes limit direct translation.
  • Diet and non-study activity were not tightly controlled.

Safety

  • All participants completed all 18 sessions.
  • The article stated no other difficulties were encountered.
  • Participants were screened to exclude chronic disease and contraindicating conditions.