Abstract P131: Racial Differences in the Response of Cardiorespiratory Fitness to Aerobic Exercise Training in Caucasian and African American Postmenopausal Women
Introduction: African American (AA) women have an elevated risk of cardiovascular disease and have been reported to have lower cardiorespiratory fitness compared to Caucasian Americans (CA) women. However, racial differences in CRF have not been evaluated specifically in postmenopausal women or following aerobic exercise training.
Methods: A cohort from the Dose Response to Exercise in Women study who were of CA (n=264) or AA (n=122) decent and were adherent to exercise training (>75%) were used in the present analysis. Participants were randomized to 4, 8, 12 kilocalories per kg body weight per week (KKW) of aerobic training or the non-exercise control group for six months. Cardiorespiratory fitness was evaluated using a cycle ergometer, and expressed in relative (mL O2•kg-1•min -1) and absolute (L O2/min) terms. An analysis of covariance was used to evaluate differences in baseline and change in cardiorespiratory fitness between CA and AA women following the intervention.
Results: AA women had lower baseline CRF when expressed in relative (CA: 15.7 vs. AA: 15.1 mL O2•kg-1•min -1, p=0.011) or absolute (CA: 1.33 vs. AA: 1.25 L O2/min, p= 0.003) terms compared to CA women. Similarly, a greater increase in relative cardiorespiratory fitness was observed in CA compared to AA women in the 4 (CA: 1.00 vs. AA: 0.35 mL O2•kg-1•min -1, p= 0.034), 8 (CA: 1.59 vs. AA: 0.82 mL O2•kg-1•min -1, p= 0.041) and 12KKW (CA: 1.98 vs. AA: 0.50 mL O2•kg-1•min -1, p=0.001) groups. Similar effects were found in absolute CRF with the exception of the 4KKW (CA: 0.04 vs. AA: 0.02, L O2/min, p= 0.147) group. However, in categorical analyses, the percentages of women who improved both relative (>0 mL O2•kg-1•min -1) and absolute (>0 L O2/min) cardiorespiratory fitness were similar for CA and AA participants in all exercise groups (all p>0.05).
Conclusions: AA postmenopausal women in general had lower baseline fitness, and an attenuated increase in cardiorespiratory fitness (both relative and absolute) following exercise training, but had similar response rates compared to CA women. Future studies should investigate the physiologic mechanisms responsible for this attenuated response.
- © 2013 by American Heart Association, Inc.