Carotid Artery Wall Mechanics During Lower Body Resistance Exercise In Strength Trained and Untrained Men.

Abstract

PURPOSE: To investigate the impact of double-leg press exercise on arterial wall mechanics (peak circumferential strain, systolic and diastolic strain rate) in the common carotid arteries (CCA) of strength trained (ST) and untrained (UT) men. METHODS: Short-axis ultrasound images of the CCA were collected in 9 ST (age: 23 ± 3 yrs; stature: 177.5 ± 5.5 cm; body mass; 89.3 ± 11.3 kg; 8 repetition maximum (8RM): 264 ± 42.5 kg) and 9 UT (age: 24 ± 4 yrs; stature: 179.5 ± 6.6 cm; body mass; 83.0 ± 11.9 kg; 8RM: 152 ± 19.9 kg) men at rest, and during double-leg press exercise at 40% and 80% of 8RM. Images were analysed for peak circumferential strain (PCS), peak systolic and diastolic strain rate (S-SR and D-SR, respectively), as well as systolic and diastolic carotid diameter (DiamSYS and DiamDIAS respectively). Systolic and diastolic brachial blood pressures (SBP and DBP, respectively) were also assessed at rest and during exercise. In addition, apical five chamber echocardiography was used to examine stroke volume (SV) in a subset of ten participants (n = 6 ST, n = 4 UT). RESULTS: Whilst S-SR and SV were not influenced by exercise intensity (P = 0.86 and P = 0.08, respectively), PCS and D-SR decreased significantly from rest to 40% 8RM (-2.7 ± 0.79 %, 95% CI: 1.0 - 4.4, P < 0.01 and -0.26 ± 0.08 1/s, 95% CI: 0.10 - 0.422, P < 0.01, respectively). There was however, no significant difference in PCS or D-SR from 40% to 80% 8RM (P = 0.126 and P = 0.467, respectively). In contrast, systolic and diastolic diameter (0.06±0.01 cm, 95% CI: 0.35 - 0.75, P < 0.01 and 0.07±0.01, 95% CI: 0.06 - 0.09, P < 0.01 respectively), SBP and DBP (31±2.3 mmHg, 95% CI: 25.9 - 35.5, P < 0.01 and 18.0±1.7 mmHg, 95% CI: 14.3 - 21.6, P < 0.01, respectively) all increased significantly from rest to 40% 8RM, but continued to increase further between 40% and 80% 8RM (all P < 0.01). No significant differences were found between ST and UT men (all P > 0.05). CONCLUSION: Acute changes in carotid arterial wall mechanics occur with the onset of lower body resistance exercise, irrespective of strength training status. Additionally, during double-leg press exercise, changes in carotid arterial wall mechanics do not occur simultaneously with changes in other haemodynamic variables, and therefore might be reflective of modifications to the intrinsic properties of the vessel wall.