{
  "schema_version": 1,
  "id": "activity-breaks-postprandial-metabolism-boundary-2026",
  "canonical_url": "https://brali-lifeos.github.io/evidence/activity-breaks-postprandial-metabolism-boundary-2026/",
  "json_url": "https://brali-lifeos.github.io/evidence/activity-breaks-postprandial-metabolism-boundary-2026/index.json",
  "decision": "propose-protocol",
  "decision_label": "Protocol candidate",
  "reviewed_at": "2026-08-30",
  "reviewed_by": "Brali Evidence Reviewer",
  "source": {
    "title": "The Acute Effects of Interrupting Prolonged Sitting With Regular Activity Breaks on Postprandial Glucose and Insulin in Adults: A Systematic Review and Meta-Analysis",
    "url": "https://onlinelibrary.wiley.com/doi/10.1111/obr.70152",
    "type": "meta-analysis",
    "doi": "10.1111/obr.70152",
    "citation_text": "Gale JT, Martin H, Haszard JJ, Peddie MC. Obesity Reviews. 2026:e70152.",
    "study_design": "Systematic review and random-effects meta-analysis of acute laboratory randomized crossover trials. Fifty-three studies met eligibility criteria and 39 were included in meta-analysis. Eligible interventions lasted at least three hours but less than 24 hours, compared prolonged sitting with at least three brief activity breaks, and measured serial postprandial glucose and/or insulin responses.",
    "population": "Adults aged at least 18 years across healthy, overweight/obesity and some clinical/metabolic-risk groups. Studies varied in age, sex, nationality, weight status, health status and laboratory protocol.",
    "intervention_or_exposure": "Interrupting prolonged sitting with regular activity breaks lasting no more than ten minutes, using standing, walking, resistance or other activity modes, compared with uninterrupted prolonged sitting of the same duration.",
    "outcomes": [
      "Postprandial glucose incremental area under the curve",
      "Postprandial insulin incremental area under the curve",
      "Subgroup estimates by activity mode",
      "Subgroup estimates by break frequency",
      "Risk-of-bias assessment"
    ]
  },
  "supported_claim": "For acute post-meal metabolism, replacing small portions of a prolonged sitting period with brief activity is better supported than remaining continuously seated. Across randomized crossover evidence, regular activity breaks reduced postprandial glucose and insulin responses, with walking producing the strongest overall mode estimates. Brali can therefore propose a bounded protocol to interrupt long sitting bouts with brief movement, especially walking when feasible, while treating the exact timing and dose as adaptable rather than universally fixed.",
  "unsupported_or_overstated_claims": [
    "A break every 20 minutes is the universal optimal schedule for all people and settings.",
    "Brief movement breaks prevent diabetes, cardiovascular disease, obesity, or mortality.",
    "The protocol improves concentration, productivity, mood, pain, or cognitive performance.",
    "Standing alone produces the same metabolic effect as walking or active movement.",
    "Brief sitting interruptions can replace recommended weekly physical activity or structured exercise.",
    "The subgroup estimates establish which BMI or clinical group will benefit most.",
    "One exact walking speed, intensity, duration, or exercise routine is required."
  ],
  "limitations": [
    "All included studies were acute laboratory randomized crossover trials lasting less than 24 hours, so the evidence does not establish long-term health effects or sustainability.",
    "Prolonged-sitting laboratory protocols, especially the longer ones, may not resemble habitual real-world sitting.",
    "Many pooled and subgroup estimates had substantial heterogeneity that remained after subgroup analysis.",
    "Most studies were rated fair or good rather than excellent; participant blinding was impossible and reporting of attrition and assessor blinding was inconsistent.",
    "The review was not prospectively registered in PROSPERO or another registry and no review protocol was prepared.",
    "The search was limited to peer-reviewed English-language studies, so relevant evidence may have been missed.",
    "Frequency and mode subgroup comparisons do not by themselves prove that the largest subgroup estimate is the optimal prescription for an individual."
  ],
  "target_hack_ids": [
    "break-up-prolonged-sitting"
  ],
  "target_protocol_ids": [
    "brali:break-up-prolonged-sitting"
  ],
  "risk_flags": [
    "health"
  ],
  "notes": "Protocol direction: when a work or leisure block has become prolonged sitting, use a low-friction cue to stand up and add brief movement such as a short walk, then return to the task. Do not market a universal 20-minute timer. The protocol should coexist with, not replace, Brali's weekly movement-baseline guidance. Track whether the pattern is feasible and whether long uninterrupted sitting actually decreases."
}