The effects of sprint interval training on endothelial function in young men and women

The benefits of exercise training on endothelial function in the healthy young population are unclear. This study was designed to assess the effects of sprint interval training (SIT; 4-7 x 30-45 s all out exercise efforts separated by 4 min of recovery, repeated 3-4 times/wk over 6 wk) on endothelial function of the superficial femoral artery (SFA) in young recreationally active men and women. Twenty-one men and twenty women arrived at the laboratory after \u3e3 h fast and were assigned randomly to SIT or Control (no training) groups. SFA diameter and blood velocity (BV) were assessed using Doppler ultrasound and imaging before and after 5 min of suprasystolic cuff inflation of the lower limb. Normalized flow mediated dilation (FMD) was analyzed as the maximal ∆ in SFA diameter (%) ÷ shear rate (mean BV x 8 ÷ SFA diameter: s-1) measured every 30 s for 5 min following cuff release. Percent FMD (% FMD) was also calculated as the maximal ∆ in SFA diameter (%). Measures were assessed before and following 6 weeks of SIT vs Control. After training, no changes in baseline SFA diameter (Women: P=0.61; Men:P=0.33), peak shear rate (30 sec average) after cuff release (Women: P=0.10; Men: P=0.22) or peak flow after cuff release (Women: P=0.15; Men: P=0.50) were observed. However; in the women SIT decreased time to peak dilation (Pre-=163±68 vs Post= 69±34 s; P=0.003), increased normalized FMD (SIT = 0.002±0.001 vs Control = 0.001±0.001 s-1; P= 0.02), and increased % FMD (SIT = 6.5±3.2 vs Control = 2.5±1.3 %; P= 0.04). There were no changes observed in the men. These data suggest that SIT improved endothelial function in the women. The mechanisms responsible as well as the reasons for the observed gender differences require further study. Key words: Flow mediated dilation, Doppler ultrasound, blood velocit