Acute arterial stiffness responses to stable vs. unstable squats: impacts of duration and intermittency

Under stable and unstable conditions, we examined acute changes in arterial stiffness in response to static squat exercises of different durations and formats (continuous or intermittent).

Healthy young adults (n = 23, 11 males and 12 females, aged 23 ± 1 years) participated in 7 trials in randomized order: no-squat control (CON), stable 1-min squat (S1), stable 6-min squat (S6), stable 6 × 1-min squat (6S1), unstable 1-min squat (U1), unstable 6-min squat (U6), and unstable 6 × 1-min squat (6U1). Arterial stiffness as assessed by cardio-ankle vascular index (CAVI) was measured repeatedly before and after exercises. CAVI changes from baseline (ΔCAVI) of the same trial were calculated.

There were no significant changes in ΔCAVI with S1 and U1 (P > 0.05). ΔCAVI decreased immediately after S6 to -0.5 ± 0.1 and 6S1 to -0.4 ± 0.1 (both P < 0.01). An increase in ΔCAVI was observed immediately after U6 to 0.4 ± 0.1 (P < 0.01), but such an increase was absent after 6U1 (P > 0.05).

Stable long squat and its intermittent form decreased arterial stiffness similarly, while unstable long squat increased arterial stiffness, with its intermittent form abolishing this increase.