Effects of a 200 W-15 min cycling exercise on postural control during quiet standing in healthy young adults.

The purpose of the present experiment was to investigate the immediate effects of a cycling exercise on postural control during quiet standing in healthy young adults. To this aim, 12 university students were asked to stand upright as immobile as possible, with their eyes closed, prior to and following a 15 min cycling exercise performed at a power output of 200 W. Centre of foot pressure (CP) displacements, recorded using a force platform along both the medio-lateral (ML) or antero-posterior (AP) axes, were used to compute the motions of the vertical projection of the centre of gravity (CG(v)) and those of the difference between the CP and the CG(v) (CP - CG(v)). Metabolic (heart rate, respiratory exchange ratio and blood lactate concentration) and psychological (rate of perceived exertion) measurements ensured that subjects were fatigued at the end of the cycling exercise. The cycling exercise induced a decreased of both CG(v) and CP - CG(v) motions along the AP-axis, whereas no significant changes were observed along the ML-axis. These discrepancies of the postural effects according to the direction of balance are likely to stem from the directionally sensitive activity of postural muscles, when considering (1) what the cycling exercise involved in terms of joints and tendons receptors stimulation and lower limb muscles recruitment (i.e. sagittal plane movers of the lower extremities) and (2) the skeletal muscles involved in postural control during quiet standing (i.e. sagittal and frontal plane movers of the lower extremities for the AP and ML balance, respectively).