Moderate Versus Heavy Intensity Interval Training For Vascular Health In Post-menopausal Women

Abstract

PURPOSE: Whilst the menopause has been associated with a decline in vascular function, sedentary postmenopausal women report a dislike of heavy intensity exercise. This study aimed to compare the impact of moderate (MOD) versus heavy (HVY) intensity interval exercise training upon vascular function and endothelial integrity. METHODS: 27 sedentary post-menopausal women completed either MOD (90% lactate threshold (LT) 10:10 s duty cycle) or HVY (120% LT 30:30 s duty cycle) interval exercise training twice per week for 12 weeks. Endothelial function (FMD), peak oxygen uptake (VO2peak), LT, circulating angiogenic cell number (FACS) and adhesive capacity to cultured saphenous vein vascular smooth muscle cells (VSMCs) were recorded prior to and following training. Group and time differences were assessed via two-way mixed mode ANOVA. RESULTS: VO2peak and LT increased in HVY only (VO2peak: MOD: 29.97 ±5.5 to 29.65 ± 5.4; HVY: 30.18 ±5.3 to 32.25 ±6.5 ml/kg/min; interaction P=0.02; LT: MOD: 1.13 ±0.19 to 1.11 ±0.18; HVY 1.09 ±0.15 to 1.22 ±0.17 L/min; interaction P=0.005). FMD (group mean: 4.7 ±2.4 %), brachial diameter (group mean: 3.7 ±0.3 mm) and blood pressure were unaffected by training (P>0.05), whilst peripheral arterial stiffness decreased post training in both groups (-0.58 a.u). [CD34+CD45dim] increased after MOD but not after HVY intensity interval training (MOD: 5.3 ±3.8 to 8.9 ±6.3; HVY: 6.34 ±3.1 to 5.7 ±2.6 CAC/105 leucocytes: interaction P=0.02). The adhesive capacity of CACs to VSMCs was seen to increase by 70% following MOD but only 12 % following HVY (P>0.05), this capacity persisted over 60 min in the MOD group (time x group interaction: P=0.05). CONCLUSION: In post-menopausal women HVY intensity interval training provided greater benefits for cardiorespiratory fitness. However, MOD intensity intervals produced equivalent reductions in arterial stiffness and greater modulation of CAC function perceived as beneficial to endothelial integrity. Neither intensity was sufficient to produce significant changes in FMD. Varying the intensities used in interval exercise prescription may provide the most effective cardiovascular benefits in post-menopausal women.