Resistance- and endurance-trained young men display comparable carotid artery strain parameters that are superior to untrained men

Abstract

Purpose: Central arterial stiffness, a predictor of cardiovascular risk, attenuates with endurance-exercise in ageing populations. However, in young individuals, this effect is inconsistent and emerging evidence suggests resistance-exercise may increase arterial stiffness. Two-dimensional (2D)-Strain imaging of the common carotid artery (CCA) is more sensitive at detecting endurance-training induced alterations in CCA stiffness than conventional methods, but has not been used to examine CCA stiffness in young resistance-trained individuals. Therefore, we compared CCA 2D-Strain parameters at rest, during acute exercise and recovery between resistance-trained, endurance-trained, and untrained young men.

Methods: Short-axis CCA ultrasound images were obtained from 12 endurance-trained [27yrs (95%CI; 24-29)], 14 resistance-trained [24yrs (23-26)] and 12 untrained [23yrs (22-24] men at rest, during isometric handgrip (IHG) exercise and recovery. 2D-Strain analysis quantified CCA peak circumferential strain (PCS) and systolic (S-SR) and diastolic (D-SR) strain rates. Conventional stiffness indices included aortic pulse-wave velocity, CCA β-stiffness (β₁) and Petersons elastic modulus (E_p).

Results: Resting conventional stiffness indices were not different between groups (P > 0.05). Resting PCS and S-SR were comparable between resistance- [11.6% (10.6-12.5) and 1.46 s^-1 (1.37-1.55), respectively] and endurance-trained [11.4% (10.7-12.2) and 1.5 s^-1 (1.38-1.62)] men and superior to untrained men [9.5% (9.19-9.9); P < 0.004 and 1.24 s^-1 (1.17 - 1.31); P < 0.018)]. Both trained groups displayed comparable reductions in PCS and S-SR during IHG, which returned to resting values during recovery (P < 0.001), whereas these parameters remained unchanged in untrained men. D-SR decreased during IHG in all groups (P < 0.001), but to a lesser extent in endurance-trained men (P < 0.023), whereas β₁ and E_p increased to a similar magnitude in all groups and returned to resting values during recovery (P < 0.001).

Conclusion: Resistance- and endurance-trained men display comparable CCA 2D-Strain parameters that are superior to untrained men, which contends previous reports that resistance-training increases CCA stiffness.

Keywords: Arterial health; Carotid artery stiffness; Endurance-exercise; Resistance-exercise; Two-dimensional strain imaging.

Fig. 1

Resting peak circumferential strain (%); ANOVA P < 0.001 (A), systolic strain-rate (s⁻¹); ANOVA P = 0.003 (B), β₂ (AU); ANOVA P = 0.021 (C); Diastolic strain-rate (s⁻¹); ANOVA P = 0.23 (D), aortic pulse wave velocity (m.s⁻¹); ANOVA P = 0.67 (E), and β₁ (AU); ANOVA P = 0.76 (F) in endurance-trained, resistance-trained and untrained men. Error bars represent SD. * Indicates P < 0.05 difference between endurance-trained vs. untrained groups. ꝉ Indicates P < 0.05 difference between resistance-trained vs. untrained groups

Fig. 2

Peak circumferential strain (%) (A), systolic strain rate (s⁻¹) (B), diastolic strain rate (s⁻¹) (C), β₂ (AU) (D), diastolic diameter (mm) (E) and β₁ (AU) (F) before (“rest”), during (“mid” and “end”) and after (“rec”) a 3 min bout of isometric hand-grip exercise in resistance-trained, endurance-trained and untrained men. Error bars represent SD. P values for the two-way ANOVA data are presented (“time”, “training” and “interaction”). * Indicates P < 0.05 difference between endurance-trained vs. untrained groups at the same time-point. ꝉ Indicates P < 0.05 difference between resistance-trained vs. untrained groups at the same timepoint