Cardiorespiratory and vascular function outcomes following 4 weeks of single-sprint training

It is unknown if brief intense exercise bouts are sufficient to improve vascular function.

Healthy participants (n=46) ages 18-35 were allocated to either a training (n=24) or control (n=22) group. Training consisted of a 20s maximal cycling sprint (no warm-up or cool-down) 3 days/week, while control received no training intervention. Testing occurred at pre-, mid- (2 weeks), and post-intervention (4 weeks). Post occlusive reactive hyperemia (PORH), brachial flow-mediated dilation, and passive leg movement hyperemia were used to assess vascular function. Graded exercise testing was used to test cardiorespiratory fitness. A Bayesian repeated measures ANOVA approach with effect estimation was used. Results are mean change (SD) from pre-to-post testing sessions with BF_incl in reference to group x time interaction.

There was no evidence of a training effect for vascular and cardiorespiratory outcomes. Changes in forearm PORH via ultrasound (cm/s) were 0.35 (11.61) for training and -1.59 (10.06) for control (BF_incl = 0.177) and via near-infrared spectroscopy (StO₂%/s) were -0.03 (0.61) for training and -0.13 (0.49) for control (BF_incl = 0.161). Changes in leg PORH via ultrasound (cm/s) were -1.20 (10.88) for training and 3.51 (15.92) for control (BF_incl = 1.070) and via near-infrared spectroscopy (StO₂%/s) were 0.15 (0.38) for training and -0.03 (0.29) for control (BF_incl = 0.492). Changes in maximal oxygen uptake (L/min) were 0.00 (0.19) for training and 0.05 (0.14) for control (BF_incl = 0.394).

Vascular and cardiorespiratory function did not show meaningful improvement, establishing an important basis for future investigation of vascular adaptations to brief intense exercise bouts.