PMID 36231609

Research
All papers

Very Low-Volume, High-Intensity Interval Training Mitigates Negative Health Impacts of COVID-19 Pandemic-Induced Physical Inactivity

Reljic D, Eichhorn A, Herrmann HJ, Neurath MF, Zopf Y

Question

Can a real-world worksite LOW-HIIT program improve cardiometabolic health in sedentary office workers, and can continued home-based LOW-HIIT mitigate lockdown-related physical inactivity effects?

Summary

A 6-month worksite cycling LOW-HIIT program in sedentary office workers improved VO2max, workload, resting heart rate, diastolic/mean blood pressure, HbA1c, and quality of life. During a subsequent COVID-19 lockdown follow-up, participants who continued home-based LOW-HIIT maintained VO2max and quality of life, while those who stopped exercise lost fitness and worsened blood pressure/quality of life. The evidence is real-world and useful, but not randomized and had substantial dropout.

Methodology

  • Previously sedentary office workers from a large company near the research center.
  • 114 participants.
  • Indoor spinning bike.
  • Work intervals: 1 minute.
  • Recovery: 1 minute low-intensity pedaling.
  • Intensity: 85-90% HRmax during weeks 1-4, 90-95% HRmax from week 5 onward.
  • 14 minutes including 2 minute warm-up and 3 minute cool-down.
  • Asked to attend 2 sessions/week; 24 possible weekly class times were offered.
  • Planned 1 year but terminated at 6 months due to COVID-19 pandemic.
  • Pre/post worksite intervention with observational 6-month follow-up subgroups
  • Cardiorespiratory fitness, Blood pressure and blood chemistry, Body composition, and Quality of life and self-reported outcomes were tracked.

Outcomes

VO2max and workload after 6 months

Participants improved VO2max, maximal workload, and workload at ventilatory threshold after the worksite intervention.

Relative VO2max +1.5 mL/kg/min, p=0.002; absolute VO2max +0.17 L, p=0.001; Wmax +22 W, p<0.001; WVT +41 W, p<0.001.

Improved

Blood pressure, HR, HbA1c

Resting HR, diastolic BP, mean arterial BP, and HbA1c decreased after 6 months.

Resting HR -18 b/min p<0.001; DBP -5 mmHg p<0.001; MAB -4 mmHg p<0.001; HbA1c -0.2% p=0.005.

Improved

Follow-up fitness

Only participants who continued home LOW-HIIT maintained VO2max; other exercise and no-exercise groups lost fitness during lockdown.

Group x time for relative VO2max p<0.001; EX -3.7 mL/kg/min p<0.001; NON-EX -5.8 mL/kg/min p<0.001.

Mixed

Adherence and acceptability

No adverse events occurred and most enjoyed/intended to continue, but dropout was substantial over the 6-month worksite intervention.

43 dropped out within first 6 months; dropout about 24% excluding COVID/unrelated disease/injury; 79% reported enjoyment and intended continuation.

Mixed

Insights

  • A 14-minute, 5 x 1-minute cycling LOW-HIIT class can be implemented at worksites and may improve fitness and cardiometabolic markers.
  • Two weekly home LOW-HIIT sessions may help preserve fitness during periods of reduced activity, but home cycling equipment availability is a barrier.
  • Real-world adherence was lower than tightly controlled lab studies, so app programs should prioritize scheduling flexibility and adherence support.

Limitations

  • No passive control group.
  • Not randomized; pre/post and observational follow-up design.
  • Previously sedentary but otherwise healthy workers only.
  • Self-reported physical activity, exercise behavior, and quality of life may be biased.
  • Diet was not standardized.
  • Home LOW-HIIT continuation depended on cycle ergometer availability.

Safety

  • No adverse events occurred during the whole intervention period.
  • One participant was excluded before starting due to health concerns detected at examination.
  • Authors recommend proper medical examination before LOW-HIIT, especially home-based LOW-HIIT after inactivity.