Short bursts of exercise may improve fitness and blood sugar in sedentary adults

by · News-Medical

Could a few minutes of movement at a time offer meaningful health benefits for people who spend much of their day sitting?

Why sitting less still matters

While adults are recommended to do at least 75 minutes of vigorous or 150 minutes of moderate aerobic activity weekly, in addition to resistance exercise at least twice a week, time constraints, medical problems, and a lack of readily available facilities make this difficult to achieve.

Nevertheless, further research is needed, as existing studies are small, short, and inconsistent.

How researchers tested the potential of exercise "snacks"

Searches used keywords and Medical Subject Headings (MeSH) in PubMed, Web of Science, Scientific Electronic Library Online (SciELO), Cochrane Central Register of Controlled Trials (CENTRAL), and China National Knowledge Infrastructure (CNKI) through February 5, 2026.

Eligible studies included sedentary adults aged 18 years or older receiving brief, structured ES compared with usual lifestyle or non-exercise interventions. Outcomes included maximal oxygen uptake (VO2max), peak oxygen uptake (VO2peak), body fat, muscle mass, strength, blood glucose, insulin, and triglycerides. Included designs were randomized controlled trials (RCTs) and non-randomized controlled trials (N-RCTs).

The Cochrane Risk of Bias 2 (RoB 2) tool assessed risk of bias for RCTs, and the Risk of Bias in Non-randomized Studies of Interventions (ROBINS-I) tool assessed risk of bias for N-RCTs. The certainty of evidence for each outcome was evaluated using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. Researchers used a random-effects meta-analysis and conducted subgroup, meta-regression, sensitivity, heterogeneity, and publication-bias analyses.

What short bursts of exercise changed

The search identified 9,981 records; 2,611 duplicates were removed, leaving 7,370 records. After screening titles and abstracts, a total of 101 full-text articles were evaluated. Of these, 80 articles were excluded, and one additional study was identified from other sources.

The review included 22 studies with 994 sedentary or inactive participants. Of the 22 studies, 18 were RCTs, and four were N-RCTs; intervention durations ranged from one day to 12 weeks and varied considerably across studies.

For cardiorespiratory fitness, 11 studies reported VO2max. ES were associated with a significant improvement in VO2max compared with control conditions; however, results varied considerably across studies. Four studies assessed VO2peak, which also improved significantly with ES.

Subgroup analyses examined sex, intervention frequency, duration, and age for VO2max, but none significantly explained differences between subgroups. Across five studies, researchers found no significant difference in muscle mass between ES and control groups. For body fat, 11 studies also found no significant improvement.

Insulin levels did not significantly improve across five studies. Three studies showed a significant improvement in triglyceride levels, while eight studies showed improved blood glucose. Muscle strength also showed no significant improvement across four studies.

The certainty of evidence was moderate for VO2max, low for VO2peak, muscle mass, triglycerides, blood glucose, and strength, and very low for body fat and insulin. Risk-of-bias assessments identified concerns in several RCTs, while about half of the N-RCTs had high risk of bias. Sensitivity analyses showed that individual studies had little influence on VO2max; however, some studies materially affected VO2peak, triglyceride, and blood glucose results. Publication bias was detected for VO2max, and the apparent benefit was no longer statistically significant after adjustment.

Where exercise snacks show promise, and where evidence falls short

ES were associated with improvements in VO2peak, triglycerides, and blood glucose among sedentary individuals. In contrast, the apparent improvement in VO2max was not statistically significant after adjustment for publication bias. ES did not significantly improve body fat, muscle mass, insulin, or muscle strength.

Because intervention types and durations varied, the certainty of evidence for most outcomes was rated as low or very low, and heterogeneity was high in many analyses. The authors also acknowledged that they registered the review with PROSPERO after completing the literature search, which may limit the protection prospective registration provides against post-hoc methodological changes. More comprehensive studies with longer follow-up periods and standardized ES protocols are needed to clarify the long-term effects of ES.

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