Citation

Maitland ME. Clin. J. Sport. Med. 2012; 22(3): 292-293.

Affiliation

University of Washington, Seattle, Washington.

Copyright

(Copyright © 2012, Canadian Academy of Sport Medicine, Publisher Lippincott Williams and Wilkins)

DOI

10.1097/JSM.0b013e318256e797

PMID

22544063

Abstract

OBJECTIVE: : To systematically review current evidence for cycling-specific health benefits. DATA SOURCES: : Using terms related to bicycle, health, morbidity, and mortality, 7 databases were searched for peer-reviewed publications in English and German language journals. Reference lists of relevant articles were scanned. STUDY SELECTION: : The inclusion criteria were observational or intervention studies, no restrictions by age or gender, quantitative measurement of cycling (excluding stationary cycling), and measures of mortality or morbidity (including risk factors) and/or of health or fitness. The searches retrieved 3534 studies, and 10 additional studies were identified. Two investigators evaluated 18 articles and agreed to include 16 studies. DATA EXTRACTION: : Data on study methods, sampling, exposure, and results were extracted onto standard forms. Methods were assessed by the Quality Assessments Tool for Quantitative Studies. Evidence was considered strong, moderate, limited, inconclusive, or no evidence, depending on the methods of the studies and the consistency of their results. Controlled intervention studies (n = 3), prospective cohort and case-control studies (n = 8), and cross-sectional studies (n = 4) were separately evaluated. MAIN RESULTS: : The 2 randomized controlled trials of cycling to work (10 and 8.5 km 1 way, on average 3 and 3.75 days per week, at a mean intensity of 65% and 60% of maximal aerobic power [V[Combining Dot Above]O2max], for 10 weeks and 6 months, respectively) found improvements in cardiorespiratory fitness among the cyclists. The third study of a 1-year nonrandomized intervention found significant increases in maximal power output and relative V[Combining Dot Above]O2max among the cyclists versus the controls. Among the cohort and case-control studies, the 3 that were methodologically strongest found an inverse association with cardiovascular disease for cycling and sports but not for gardening and walking (10-year follow-up), and a nonsignificantly lower risk of all-cause mortality for those who cycled most (6-year follow-up) and less than half the risk of colon cancer among both men and women who cycled >120 minutes per day versus <30 minutes per day (case-control study). Among the 3 studies that were moderately rigorous, cardiorespiratory fitness improved in boys and girls who changed to cycling (6-year follow-up); no differences were found in a population-based follow-up for all-cause or cardiovascular mortality among persons who cycled for <30 minutes or >30 minutes per week; and there was a significant weight loss for nurses who cycled or walked briskly for 30 minutes per day but not for those who walked slowly (16-year follow-up). Among the cross-sectional studies, the 2 reports that were moderately rigorous found school children who cycled to school had greater aerobic power, muscle endurance, and flexibility and were more likely to be in the top quartile of fitness than walkers or passive travelers. Among the 6 studies that looked at dose-response of cycling, greater health benefits (eg, 30% increase in fitness) were shown with lower initial fitness and shorter initial trip distances, whereas there was little change with higher initial fitness. Improvements in fitness continued for 6 months of cycling but then leveled off. Greater weekly total energy expenditure (>1000 and >1500 kcal/week for women and men, respectively) in cycling was associated with gains in V[Combining Dot Above]O2max. Greater weekly duration or energy expenditure in cycling was associated with a lower risk of all-cause mortality, cancer, and specifically colon cancer. Cardiovascular disease incidence decreased for up to 3.5 hours per week of cycling and for a greater cycling volume when there was additional participation in sport (adjusted hazard ratio, 0.63) in comparison with those who neither cycled nor played sports. CONCLUSIONS: : Cycling benefited adults and children in a dose-response manner. It improved cardiorespiratory fitness (strong evidence), showed benefits in cardiovascular risk factors (moderate evidence), and may have reduced all-cause, cardiovascular, and cancer mortality and contributed to weight loss (inconclusive evidence).

Language: en