Acute Effect Of Repeated Bouts Of Supramaximal Exercise On Carotid Wave Intensity

Repeated bouts of supramaximal exercise may induce changes in hemodynamics during recovery in young and healthy women. Wave intensity analyses (WI) offers insight into the interaction of the heart and vasculature in response to repeated bouts of supramaximal exercise. The 1st positive wave (W1) occurs during early systole and represents left ventricular contractility. The 2nd positive wave (W2) is associated with ventricular function during end-systole/early-diastole and follows a period of relatively small backward-traveling compression wave referred to as negative area (NA), that may be caused by reflected waves from the brain. PURPOSE: To investigate the effects of repeated bouts of supramaximal exercise on carotid WI in young and healthy women. METHODS: Eleven normotensive young and healthy women (age: 22 ± 3 years; BMI = 23.0 ± 2.6 kgm-2) performed 2 bouts of the steep ramp test (SRT) on a cycle ergometer separated by 30 minutes of supine recovery. During SRT, participants cycled unloaded for 2 minutes followed by increasing work rate of 25 Watts every 10 seconds until exhaustion. Wave intensity measurements were performed at the right common carotid at rest (R), 5 min (SRT1-P5) and 30 min (SRT1-P30) after the first SRT, and 5 min (SRT2-P5) and 30 min (SRT2-P30) after the second SRT. WI is the product of time derivates of flow velocity and pressure. One-way repeated-measures ANOVA with Bonferroni post-hoc analysis was used. RESULTS: There were significant main time effects for W1 (9.4 ± 0.4, 9.8 ± 0.4, 9.6 ± 0.3, 9.9 ± 0.3, and 9.8 ± 0.3 mmHg m s-3 for R, SRT1-P5, SRT1-P30, SRT2-P5, and SRT2-P30, respectively; p < 0.05) and NA (4.2 ± 0.6, 5.0 ± 0.4, 4.3 ± 0.5, 5.1 ± 0.5, and 4.5 ± 0.4 mmHg m s-2 for R, SRT1-P5, SRT1-P30, SRT2-P5, and SRT2-P30, respectively; p < 0.05). Compared to rest, W1 was significantly higher at SRT2-P30 (p < 0.05). NA increased at 5 min after each exercise bout (p < 0.05) and recovered by 30 min (p < 0.05). W2 did not change over time. CONCLUSIONS: After consecutive bouts of supramaximal exercise, young and healthy women exhibit sustained increases in left ventricular contraction and transient increases in backward-traveling compression waves.