# Very Low-Volume, High-Intensity Interval Training Mitigates Negative Health Impacts of COVID-19 Pandemic-Induced Physical Inactivity PMID: 36231609 Journal: International journal of environmental research and public health Published: 2022 Sep 28 Authors: 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. ## Population - Previously sedentary office workers from a large company near the research center. - Sample size: 114 - Age: 48 +/- 10 years at baseline invitation; 50 +/- 10 among T2 completers - Sex: 44% female at baseline, 39% female at T2, 33% female at T3 - Fitness level: Self-reported sedentary for at least 1 year; less than 30 min moderate activity 3 times/week and no specific exercise training - Health status: Otherwise healthy office workers; excluded heart disease, cancer, severe orthopedic conditions/injuries, pregnancy, and prior COVID-19 diagnosis ## Methodology - Pre/post worksite intervention with observational 6-month follow-up subgroups - 6-month intervention plus 6-month follow-up - Worksite group cycling classes, then home-based exercise during COVID-19 lockdown ## Protocol - Worksite LOW-HIIT. - Modality: Indoor spinning bike. - Work intervals: 1 minute. - Recovery: 1 minute low-intensity pedaling. - Sets or repetitions: 5 interval bouts. - Intensity: 85-90% HRmax during weeks 1-4, 90-95% HRmax from week 5 onward. - Session duration: 14 minutes including 2 minute warm-up and 3 minute cool-down. - Frequency: Asked to attend 2 sessions/week; 24 possible weekly class times were offered. - Program length: Planned 1 year but terminated at 6 months due to COVID-19 pandemic. - Progression: Minimum target HR increased after week 4. - Follow-up behavior groups. - Modality: Unsupervised home LOW-HIIT, other home exercise, or no exercise during lockdown. - Work intervals: HIIT group continued LOW-HIIT pattern; exact home protocol not fully detailed. - Recovery: HIIT group continued LOW-HIIT pattern. - Intensity: Self-reported home LOW-HIIT or other exercise. - Frequency: HIIT about 2 weekly sessions per discussion; EX about 1.8 sessions/week and 42 min/week. - Program length: 6-month lockdown follow-up. ## Outcomes ### VO2max and workload after 6 months Status: improved 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. ### Blood pressure, HR, HbA1c Status: improved 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. ### Follow-up fitness Status: mixed 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. ### Adherence and acceptability Status: mixed 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. ## Practical 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 And Adherence - 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. ## Original Sources - [PubMed](https://pubmed.ncbi.nlm.nih.gov/36231609/) (pubmed) - [DOI](https://doi.org/10.3390/ijerph191912308) (doi) - [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9565952/) (full text) ## Agent Guidance Preserve the paper-level scope of this note. Do not generalize beyond the population, protocol, measured outcomes, and limitations above.