Summary of recent studies assessing the association between regular PA and SI
| Reference | Participants | Study type | PA or other data collected | Outcome measure | Authors' conclusions and comments |
| Uemura et al46 | Five hundred and eighteen eligible subjects (380 men and 138 women) who attended the Tokushima Prefectural General Health Checkup Center. | Survey. | Questionnaire on lifestyle characteristics, including leisure-time exercise and daily non-exercise activities. | Subjects with longer durations of daily non-sedentary activities had significantly lower adjusted ORs for MetS. Daily non-sedentary activities were associated with lower HOMA-IR. | A lifestyle involving greater time spent in non-sedentary activities reduced the risk of IR. |
| Rosenberger et al47 | Three hundred and one overweight/obese patients with prediabetes. | Survey of PA habits. | Participants reported walking and other activities, and were assessed for factors associated with MetS. Participants were categorised as those with and those without MetS. | Eighteen per cent of subjects with MetS reported at least 150 min of activity minutes per week compared with 29.8% of those without MetS. The odds of MetS was lower with greater activity minutes. | Meeting PA goals of 150 min/week, reduced MetS odds in overweight/obese adults with prediabetes. |
| Caro et al48 | One hundred and one adults with no personal history of disease aged 30–70 years. | A cross-sectional, observational study in an adult population. Participants were age-matched and sex-matched for comparison. | Participants were classified into: (1) those who undertook regular exercise of 30–60 min of moderate physical exercise 5 days per week, and (2) non-exercising controls who exhibited a sedentary lifestyle. | Indicators of fasting plasma insulin levels HOMA-IR were significantly lower in the regular PA group. Prevalence rates of MetS were 20.7% and 45.8% in the regular PA and sedentary groups, respectively. | Moderate regular PA is associated with higher SI. |
| Jiménez-Pavón et al49 | One thousand and fifty-three boys and girls, aged 12.5–17.5 years. | A cross-sectional study in a school setting. | PA was assessed via accelerometry; CRF assessed via a 20 m shuttle run test. Fasting insulin and glucose concentrations were measured. The HOMA-IR and quantitative SI index were calculated. | In men, VPA was negatively associated with markers of resistance (IR) after adjusting for confounders including waist circumference. In women moderate PA, moderate PA to VPA, and average PA were negatively associated with markers of IR after adjusting for confounders. When the sample was segmented by CRF levels, all the PA intensities were significantly negatively associated with the markers of IR in women with low CRF but not in those with middle-high CRF after adjusting for confounders. | The findings suggest that PA is negatively associated with markers of IR after adjusting for confounders including total and central body fat in both sexes. This relationship is modified by the CRF levels, which are especially important in those women with low CRF. Preventive strategies should focus on increasing the volume of PA and on enhancing CRF through VPA. |
| Telford et al50 | Seven hundred and eight primary school children, mean age 8.1±0.35 years. | Four-year cluster-randomised intervention study into the effects of specialists versus non-specialists delivering physical education classes. | The intervention involved the employment of specialist physical education teachers to deliver PE classes (intervention) in primary schools, rather than delivery by generalist primary teachers (control). | The PE classes delivered by the PE specialists involved more fitness work than the control PE classes delivered by primary generalists (7 min vs 1 min) and more moderate PA (17 min vs 10 min, respectively). There were no differences at baseline, but by grade 6, the intervention had lowered the prevalence of IR by 14% in the boys and by 9% in the girls, also the percentage of children with IR > 3 (a cut-off point for metabolic risk) was lower in the intervention than in the control group (combined, 22% vs 31%; boys, 12% vs 21%; girls, 32% vs 40%). | Specialist-taught primary school PE increased physical activity in PE classes, and was associated with a lower prevalence of IR in community-based children. |
CRF, cardiorespiratory fitness; HOMA-IR, homoeostasis model of assessment-insulin resistance; IR, insulin resistance; MetS, metabolic syndrome; PA, physical activity; SI, insulin sensitivity; VPA, vigorous physical activity.