Aerobic exercise → Insulin resistance (HOMA-IR)

Mechanism

Gray randomized 48 adults in Glasgow, mean age 49, to keep their usual walking or to add about 3,000 pedometer steps a day on five days a week. The intervention arm rose from 6,682 to 10,182 steps a day. The control arm stayed near 6,400. Blood at baseline and at 12 weeks was assayed for glucose, insulin, hsCRP, IL-6, soluble IL-6 receptor, TNF-alpha, and the two soluble TNF receptors. None of those blood markers moved in either arm. The authors conclude that this community walking dose did not change insulin sensitivity or systemic inflammation. The assigned object is walking. Fasting insulin and glucose are the inputs to HOMA-IR. The the record here abstract does not report a HOMA number. Gray did not set a heart-rate range. SMILE-style treadmill sessions are not this trial.

Caveats

Forty-eight people, 11 of them men. Twelve weeks. Community pedometers, not supervised sessions at 70 to 85 percent of heart-rate reserve. The abstract names 48 people. A null in a sample this size can be a true null for this dose or a miss. The authors report no change in any measured variable. They do not publish an effect size in the abstract. This page is not lifting. Waters and Ho sit on the resistance-training edge. It is not unbroken sitting. Dempsey sits on that page. It is not a diet-plus-exercise kitchen sink. This is not medical advice and not a walking prescription.

Effect

qualitative. Gray 2009: +3000 steps/d on 5 d/wk vs no change, n=24+24, 12 wk. Fasting glucose, insulin, inflammatory markers unchanged. Insulin sensitivity null.

Nodes

Named confounders

• Prolonged sitting
• Resistance training
• Ultra-processed food intake
• Sleep duration and regularity

Papers

• The effect of a 12 week walking intervention on markers of insulin resistance and systemic inflammation.

  SR Gray, G Baker, A Wright, CF Fitzsimons, N Mutrie, MA Nimmo · 2009 · Preventive medicine