Effects On Aerobic Capacity Of Three 48-week Community-based Exercise Interventions

Abstract

A sedentary lifestyle is associated with cardiovascular disease (CVD). A substantial and compelling body of evidence demonstrates reduced CVD risk following systematic physical activity (PA). Despite this evidence, CVD continues to rise, and public health PA initiatives appear to be failing to demonstrate clinically relevant effects. PURPOSE: A core component of cardiovascular health is the ability to utilise oxygen, termed ‘oxygen uptake’ or VO2. We investigated the effectiveness of three physical activity interventions on oxygen uptake. We did so using a Phase-IV clinical trial model, in which all treatments were administered in uncontrolled community settings, and in which all interventions and measures were delivered by, and conducted by, community health centre staff. METHODS: Participants were sedentary individuals receiving no medication to reduce CVD risk (n=238, age 43±5 years). Participants selected a PA or exercise (EX) pathway. Those who selected PA were randomised to either fitness centre based physical activity counselling delivered by an exercise professional (PAC) or a wait-list control condition (CON). Those who selected EX were randomised to either a structured exercise program (STRUC) or unstructured fitness centre use (FREE). The dependent measure was predicted maximum oxygen uptake (VO2 max; ml/kg/min), measured using the COSMED Fitmate. Measures were taken at baseline and 48 weeks. RESULTS: Repeated measures ANOVA indicated no statistically significant difference between treatments (F [3,215] = 1.173, p = .321), and paired-sample t-tests indicated no significant pre-post effects for any treatment. When data were grouped using a quartile split by baseline VO2 max however, repeated measures ANOVA indicated significant differences between groups (F [3,215] = −6.1, p < .001), specifically that whilst in the highest two quartiles VO2 max was reduced (M = -2.7, SD = 7.0, p=.05 and M = -2.6, SD = 6.0, p=.008 respectively), and no significant change was observed in the third quartile (M = -0.1, SD = 5.0, p = .89), in the lowest quartile, VO2 max was significantly increased (M = 4.1, SD = 6.6, p < .001). CONCLUSIONS: Data suggest that in terms of VO2, treatments in the current study were more effective with the least fit participants at baseline, and actually counter-productive for the most fit.