Cardiorespiratory fitness and vision loss among young and middle-age U.S. adults

Purpose. To examine the association between vision loss and cardiorespiratory fitness among young and middle-age U.S. adults. Design. The study had a cross-sectional design. Setting. The National Health and Nutrition Examination Survey 1999-2004 served as the study setting. Subjects. Study subjects included 3135 adults ages 20 to 49 years. Measures. Cardiorespiratory fitness was assessed from cardiorespiratory extrapolation using heart rate response during submaximal treadmill testing, with inadequate cardiorespiratory fitness defined as below the 60th percentile for age and gender. Visual acuity was objectively assessed for each eye. Analysis. Multivariable regression (linear and logistic) models were computed to examine the association between cardiorespiratory fitness and vision. Results. Poorer cardiorespiratory fitness (β=-3.7 mL O₂/kg per minute; 95% confidence interval:-5.3 to-2.2) was observed in subjects with visual impairment after adjusting for age, gender, race/ethnicity, and comorbid illness. Participants with vision impairment, as compared with those with normal sight, had 4.4-fold higher odds of having inadequate cardiorespiratory fitness (95% confidence interval: 1.04-18.97), whereas participants with uncorrected refractive error were not more likely to demonstrate poorer cardiorespiratory fitness. Conclusion. Adults with visual impairment, but not adults with uncorrected refractive error, demonstrate a significant reduction in cardiorespiratory fitness and are much more likely to have inadequate fitness compared with those with normal vision. Evaluation and implementation of strategies to increase cardiorespiratory fitness among those with vision impairment, in particular, are needed.