Vascular adaptations following an eight-week sprint interval training intervention in healthy men.

Background: Sprint interval training (SIT) has been shown to improve many indices of cardiovascular risk. The effect of SIT on emerging indicators of cardiovascular health, including arterial stiffness and carotid intima media thickness, remains unclear. Thus, the purpose of this study was to assess changes in augmentation index at 75 beats per minute (AIx@75), pulse wave velocity (cfPWV), and carotid intima media thickness (CIMT) at three time points of an 8-week SIT intervention.

Methods: Eighteen sedentary men (age: 24.7±5.1 years, BMI: 26.7±5.8 kg/m²) participated in the study. Subjects trained 3 times a week for 8 weeks. Training consisted of 3-6 consecutive 30-second bouts of maximal intensity cycling, with 4.5 minutes of active recovery between bouts. Baseline, 4-week, and 8-week vascular assessments were performed. Training effects were analyzed using repeated measures ANOVA. Pearson correlations were used to determine the relationship between baseline values and the change scores (baseline to 8 weeks) of each vascular measure.

Results: AIx@75 (BL: -3.6±10.9%, 4W: -5.6±8.3%, 8W: -3.2±9.5%), cfPWV (BL: 5.6±1.0 m/s, 4W: 5.8±0.9 m/s, 8W: 5.6±0.7 m/s), and CIMT (BL: 0.51±0.08 mm, 4W: 0.52±0.08 mm, 8W: 0.51±0.08 mm) did not significantly change (all P>0.05). Baseline cfPWV and AIx@75 were negatively correlated to their change from baseline to 8 weeks (P<0.05).

Conclusions: These findings demonstrate that 8 weeks of SIT is an insufficient stimulus to reduce cfPWV, AIx@75, or CIMT in a group of young, healthy men. Baseline arterial stiffness may modulate vascular adaptations to SIT.