Acute arterial stiffness responses to various bouts of grounded and heightened one-leg standing

To examine acute effects of various bouts of grounded and heightened one-leg standing (OLS) on arterial stiffness of supporting and non-supporting side, and to investigate the possible role of muscle activity of supporting leg.

Twenty-two healthy young adults (24.3 ± 0.3 years) underwent 7 conditions using random crossover fashion: no-intervention control (CON), grounded OLS for 1 × 3 min (G1), 2 × 3 min (G2) and 3 × 3 min (G3), and heightened OLS for 1 × 3 min (H1), 2 × 3 min (H2) and 3 × 3 min (H3). Bilateral arterial stiffness measurements using cardio-ankle vascular index (CAVI) were performed at baseline (BL), immediately (0 min) and every 10 min after OLS. CAVI changes from BL in the same condition (∆CAVI) were analyzed. Root mean square (RMS) from electromyography was used to reflect gastrocnemius muscle (GS) activity.

As to supporting side, ∆CAVI remained unchanged in G1, G2 and G3, and decreased in H1 with - 0.4 ± 0.1 and in H2 with - 0.5 ± 0.1 relative to CON at 0 min; however, it increased in H3 with 0.5 ± 0.1 relative to CON at 0 min. ∆CAVI changes of non-supporting side were similar to those of supporting side in all corresponding conditions. RMS of GS from supporting leg was increased in heightened OLS (P < 0.01).

Grounded OLS has no impacts on AS regardless of standing dose, and heightened OLS results in AS decrease and increase with increasing standing bouts. AS changes induced by height exposure are bilateral, and might be related to increased GS activity of supporting leg.