Acute effects of the different relaxation periods during passive intermittent static stretching on arterial stiffness

Abstract

To clarify whether the relaxation period during stretching affects the degree of elevated shear rate and the degree of reduction of arterial stiffness, we examined relaxation duration to build an adequate stretching protocol. In Experiment 1, the changes in cardiac output, the shear rate in the posterior tibial artery, and blood volume in the calf muscle were measured during recovery (0–60 s) from a single bout of one-legged passive calf stretching in 12 healthy young men. In Experiment 2, the effects of different relaxation periods (5-, 10-, 20-, and 60-s) of passive one-legged intermittent calf stretching (30-s × 6 sets) on the femoral-ankle pulse wave velocity (faPWV) as an index of peripheral arterial stiffness were identified in 17 healthy young men. As a result, the stretched leg’s shear rate significantly increased from 0 to 10th s after stretching. The muscle blood volume in the stretched leg significantly reduced during stretching, and then significantly increased during the recovery period after stretching; however, cardiac output remained unchanged during stretching and recovery. Additionally, the reduction in faPWV from the pre-stretching value in the stretched leg was significantly larger in the protocol with 10-s and 20-s relaxation periods than that in the non-stretched leg, but this did not differ in the 5-s and 60-s relaxation periods. These findings suggest that the relaxation periods of intermittent static stretching that cause a high transient increase in shear rate (via reperfusion after microvascular compression by the stretched calf muscles) are effective to reduce arterial stiffness.

Effects of acute cervical stretching on arterial wall elastic properties

“…Acute stretching of a local body part is well known to elicit an increase in arterial compliance and a reduction in arterial stiffness in that body part ( Yamato et al, 2017 ; Higaki et al, 2021 ; Ikebe et al, 2022b ). Our results are consistent with those of previous studies and indicate that acute cervical stretching increased carotid arterial distensibility without reducing systemic arterial stiffness (haPWV and CAVI).…”

“…Indeed, the findings of animal studies indicate that arterial structural changes (i.e., in the composition of elastin and collagen) are less likely to occur in a relatively short period (Tanaka et al, 2000;Nosaka et al, 2003;Maeda et al, 2005). Second, in terms of arterial functional factors, previous studies have reported that stretching induces blood flow and shear rate during the relaxation period (Yamato et al, 2021), and that this stimulus can cause a reduction in arterial stiffness (i.e., an increase in arterial compliance) after stretching (Hotta et al, 2013;Higaki et al, 2021;Yamato et al, 2021;Hotta et al, 2018). In our experimental data, an increasing tendency of shear stress immediately after cervical stretching was observed (CON vs. CS: 1.4 ± 5.9% vs. 10.7 ± 5.1%).…”

“…Furthermore, regular ( i.e., mid- or long-term) stretching exercises increase arterial compliance and/or reduce arterial stiffness ( Cortez-Cooper et al, 2008 ; Nishiwaki et al, 2015 ; Shinno et al, 2017 ; Ikebe et al, 2022a ). Acute ( i.e., immediate) local stretching exercises would also reduce corresponding local arterial stiffness ( Yamato et al, 2017 ; Higaki et al, 2021 ; Ikebe et al, 2022b ). Thus, these findings indicate that some physiological mechanisms (namely, arterial structural factors and/or arterial functional factors, but not confounding factors) participate in the relationship between body flexibility and arterial function status and stretching training adaptations.…”

Four weeks of lower-limb static stretching reduces regional arterial stiffness in middle-aged and older women

“…To reduce the degree of reduction in arterial stiffness, continuous high shear stress (e.g., shear rate) on endothelial cells induces vasodilation with increased secretion of endothelial-derived relaxation factor [ 20 - 24 ]. We, as well as others, have demonstrated that acute passive static stretching of the quadriceps or calf muscle increased blood flow and shear rate in the stretched leg [ 15 , 16 , 25 - 27 ]. Conversely, the blood flow and shear rate in the non-stretched leg did not change [ 15 , 25 ].…”

“…We, as well as others, have demonstrated that acute passive static stretching of the quadriceps or calf muscle increased blood flow and shear rate in the stretched leg [ 15 , 16 , 25 - 27 ]. Conversely, the blood flow and shear rate in the non-stretched leg did not change [ 15 , 25 ]. Therefore, these findings suggest that habitual repetition of the increase in shear rate induced by stretching of the lower limb may result in reduced arterial stiffness.…”