Abstract
BACKGROUND AND OBJECTIVE The energetic cost of cycling (CE) is a major contributor to cycling performance but whether CE can be improved by exercise intervention remains uncertain. Here, we sought to systematically review and determine the effect of exercise training on CE in healthy humans. METHODS MEDLINE, Scopus, and Web of Science were searched since their inceptions up until December 2014 for articles assessing the effect of exercise training in healthy subjects on CE, as determined by cycling economy or efficiency. Meta-analyses were performed to determine the standardized mean difference (SMD) in CE between post- and pre-training measurements. Subgroup and meta-regression analyses were used to evaluate potential moderating/confounding factors. RESULTS Fifty-one studies were included after systematic review, comprising a total of 531 healthy subjects (mean age = 20-66 years). Exercise interventions primarily consisted of endurance and/or strength training ranging from 4 to 34 weeks of duration. After data pooling, the meta-analysis revealed that CE was improved with strength training alone or along with endurance training (n = 16, SMD = -0.50, P < 0.0001) but not with endurance training alone (n = 33, SMD = -0.18, P = 0.08). In further subgroup analyses, endurance training alone was effective in improving CE in previously untrained (n = 20, SMD = -0.21, P = 0.04) but not in trained (n = 6, SMD = 0.09, P = 0.75) subjects. The SMD in CE was associated with the duration of training (n = 51, B = -0.03, P = 0.0002). CONCLUSION The current meta-analysis provides evidence that CE is improved by exercise training, particularly when strength training or untrained subjects are included.
