Sex Differences in Cardiorespiratory Fitness and All-Cause Mortality

Abstract

Objective To determine whether sex modifies the relationship between fitness and mortality. Patients and Methods We included 57,284 patients without coronary artery disease or heart failure who completed a routine treadmill exercise test between 1991 and 2009. We determined metabolic equivalents of task (METs) and linked patient records with mortality data via the Social Security Death Index. Multivariable Cox regression was used to determine the association between sex, fitness, and all-cause mortality. Results There were 29,470 (51.5%) men and 27,814 (48.6%) women with mean ages of 53 and 54 years, respectively. Overall, men achieved 2 METs higher than women (P<.001). Over a median of 10 years follow-up, there were 6,402 deaths. The mortality rate for men in each MET group was similar to that of women who achieved an average 2.6 METs lower (P=.03). Fitness was inversely associated with mortality in both men (HR 0.84 per 1 MET; 95% CI: 0.83, 0.85) and women (HR 0.83 per 1 MET; 95% CI: 0.81, 0.84). This relationship did not plateau at high or low METs values. Conclusions While men demonstrated 2 METs higher than women, their survival was equivalent to women demonstrating 2.6 METs lower. Further, higher METs were associated with lower mortality for both men and women across the range of MET values. These findings are useful for tailoring prognostic information and lifestyle guidance to men and women undergoing stress testing.

Exercise training improves sleep quality: A randomized controlled trial

“…These differences may explain the fact that women did not improve total sleep time after the intervention programme, mainly due to the differences in exercise physiology between men and women . For example, women have lower gains in muscle mass, lower cardiorespiratory fitness or lower muscle strength among others. Additionally, benefits of exercise appeared to be stronger for men than women in sleep parameters .…”

Individual and interpersonal correlates of cardiorespiratory fitness in adults – Findings from the German Health Interview and Examination Survey

“…In the current study, women had 17% lower  VO max 2 than men, which is comparable to an often reported sex difference in CRF of about 20% 8,11 . Lower fitness among women compared to men is commonly explained by women's smaller organ and body size and higher percentage of body fat on average and lower skeletal muscle mass 7,44 . Additional analyses with sex as an additional covariate showed that sex differences are not mediated by the anthropometric, behavioral, sociodemographic and interpersonal factors used in the fully adjusted model.…”

Trends in cardiorespiratory fitness: The evolution of exercise treadmill testing at a single Academic Medical Center from 1970 to 2012

“…23 For example, testing exercise capacity using exercise testing with or without gas exchange unmasks gender differences in the relationship of fitness to cardiovascular risk: even though men only achieve 1.7 greater METs on average, women have the same predicted mortality as men with 2.6 greater MET capacity. 24 Despite guideline-supported recommendations and the added clinical value of measuring exercise capacity (CRF), our ETT laboratory experience and that of other institutions appear to be moving towards less use of ETT. 25 This trend may eventually lead to adverse clinical outcomes when less predictive, more costly tools are relied upon in place of ETT.…”