Objectively-measured physical activity and its association with adiponectin and other novel metabolic markers: a longitudinal study in children (EarlyBird 38)

Abstract

Objective: Recent evidence suggests that, in children, traditional markers of metabolic disturbance are related only weakly to physical activity (PA). We therefore sought to establish the corresponding relationships with newer metabolic markers.

Research Design and Methods: This is a non-intervention longitudinal study of 213 healthy children recruited from 54 schools in Plymouth, UK. MTI accelerometers were used to make objective seven-day recordings of PA at ages 5y (SD ±0.3y), 6y, 7y and 8y. Overall PA was taken as the average of the four annual time points. The metabolic markers at 8y were adiponectin, leptin, high sensitivity C-reactive protein (hsCRP) and insulin resistance (HOMA-IR). Potential confounders included percent body fat (%BF) measured by DEXA and diet measured by food frequency questionnaire.

Results: While PA did not correlate with IR (r=−0.01), leptin (r=+0.04) or hsCRP (r=+0.01) independently of %BF, it did with adiponectin, but inversely (r=−0.18 p=0.02). This unexpected inverse relationship was strongest among the less active children (PA<median: r= −0.30, p=0.01) but negligible in the more active children (PA>median: r=+0.04, p=0.76). Adiponectin was significantly higher (0.52SD, p<0.01) in the least active tertile compared to the other two tertiles. Insulin resistance, however, did not differ across the PA tertiles (p=0.62).

Conclusions: Adiponectin levels in children are highest among those who are least active but their insulin resistance is no different. Adiponectin has a known insulin-sensitizing effect, and our findings are consistent with a selective effect at low levels of physical activity.