Effect Of A Brief Bout Of Post-Resistance Training Cycling Exercise On Aortic Stiffness

PURPOSE: Resistance training (RT) has been shown to increase aortic stiffness both acutely and chronically, whereas endurance training (ET) tends to reduce it. However, RT-focused individuals may avoid prolonged ET bouts due to lack of training specificity or concerns of interference effects, highlighting the need to investigate the effects of shorter ET protocols on central arterial compliance. Thus, we aimed to determine whether a brief bout of ET performed post-RT attenuates acute increases in aortic stiffness. METHODS: Twelve men (23.2 ± 3.8 years, 26.7 ± 3.4 kg/m2, 4.1 ± 2.0 years of RT experience) performed identical bouts of RT on separate days with and without 10 min of post-RT ET on an air bike (70% of age-predicted maximal heart rate) in a counterbalanced order. The RT protocol involved 5 sets of 5 repetitions of the bench press (95% of 5 repetition maximum [RM]) and 5 sets of 10 repetitions of the arm curl (95% of 10 RM). Carotid-femoral pulse wave velocity (cfPWV, an index of aortic stiffness) was obtained in the supine position following 5 min of stabilization immediately pre-RT, immediately post-RT, and again 5-, 15-, and 30-min post-ET intervention or control (10 min seated rest). RESULTS: A significant main effect of time was observed for cfPWV (P < 0.0001). Post-hoc analyses showed that cfPWV immediately post-RT (6.0 ± 0.7 m/s) was greater (Ps <0.0001) than all other time points (5.5 ± 0.6 - 5.6 ± 0.6 m/s). No condition (P = 0.74) or condition × time interaction (P = 0.16) effects were observed. Following the ET intervention, greater reductions in cfPWV at post-30 relative to immediately post-RT were associated (r = 0.732, P < 0.01) with lower relative cycling power output (W/kg). CONCLUSIONS: A brief bout of moderate intensity ET did not alter group-level aortic stiffness responses post-RT. However, the ET intervention was more effective in reducing cfPWV among participants with lower cardiorespiratory fitness, inferred from relative cycling power output. Supported by: Funded by the National Strength and Conditioning Association Graduate Student Research Grant-Masters