A comparison of postexercise shear rate patterns following different intensities and durations of running in healthy men.

PURPOSE: We tested the hypothesis that high-intensity exercise would elicit the greatest alterations in postexercise shear rate (SR) patterns when compared to moderate intensity exercise, and moderate duration exercise would produce similar postexercise SR patterns as long-duration exercise. METHODS: On separate days, ten healthy men completed three acute treadmill exercise sessions at different intensities and/or durations. Sessions were 80% VO(2peak) for 30 min (HIGH), 50% VO(2peak) for 30 min (MOD) and 50% VO(2peak) for 60 min (MOD(L) . SR in the brachial artery was assessed at baseline, immediately postexercise, 1 and 2 h postexercise using Doppler ultrasound. RESULTS: Oscillatory and retrograde SR decreased immediately following all exercise sessions (P<0·01) and returned to baseline at 1 h postexercise; however, there were no differences between sessions (P>0·08). Antegrade and mean SR were elevated immediately following all exercise sessions (P<0·01), and the greatest elevations were observed following the HIGH session (P<0·05). Antegrade and mean SR declined below baseline values at 1 h (P<0·05) and 2 h (P<0·05) after the MOD(L) session and 2 h following the HIGH session (P<0·05). CONCLUSION: Antegrade and mean SR immediately following running exercise are dependent upon exercise intensity. Reductions in oscillatory and retrograde SR after treadmill running are not dependent on exercise intensity or duration and appear to last <1 h. Collectively, SR profiles following exercise are differentially altered based on the dose of exercise performed.