Purpose: To examine and compare the acute effects of moderate-intensity continuous and accumulated exercise in three bouts with different intervals on arterial stiffness.
Method: Nineteen healthy young males (mean age = 24.7 years) were randomized to no-exercise control (CON), continuous exercise (CE, 30-min cycling), accumulated exercise with 10-min intervals (AE10, 3 × 10-min cycling, 10-min interval), and accumulated exercise with 60-min intervals (AE60, 3 × 10-min cycling, 60-min interval) trial in balanced self-control crossover design. The intensity in all the exercise trials was set at 50% heart rate reserve. Cardio-ankle vascular index (CAVI), an index of arterial stiffness, was measured at baseline (BL), immediately after (0 min) and 60 min after the completion of the exercise.
Results: CAVI remained stable (6.8 ± 0.1, 6.8 ± 0.2, 6.9 ± 0.1 at BL, 0 and 60 min, respectively) in CON trial. Immediately after exercise, CAVI in CE, AE10 and AE60 trials all decreased significantly to similar degree compared to CON trial (P < 0.05 for CE, AE10 and AE60 vs. CON). Though CAVI in CE trial returned to baseline level after 60 min of recovery, CAVI in both AE10 and AE60 trials remained significantly low compared to CON trial (P < 0.01 for AE10 and AE60 vs. CON).
Conclusion: When the total duration and relative intensity were matched, the effects of accumulated exercise in three bouts were superior to continuous exercise. Elongation of intervals between bouts did not attenuate the superior effects of accumulated exercise on arterial stiffness.
Trial registration: ChiCTR-OTRCC-14005229.
Keywords: Accumulated exercise; Arterial stiffness; Continuous exercise; Interval duration.