Racial differences in the response of cardiorespiratory fitness to aerobic exercise training in Caucasian and African American postmenopausal women

Damon L. Swift, Neil M. Johannsen, Carl J. Lavie, Conrad P. Earnest, William D. Johnson, Steven N. Blair, Timothy S. Church, Robert L. Newton

African American (AA) women have an elevated risk of cardiovascular disease and have been reported to have lower cardiorespiratory fitness (CRF) compared with Caucasian American (CA) women. However, little data exist that evaluate racial differences in the change in CRF following aerobic exercise training. CA (n = 264) and AA (n = 122) postmenopausal women from the Dose-Response to Exercise in Women study were randomized to 4, 8, and 12 kcal·kg body wt(-1)·wk(-13) (KKW) of aerobic training or the control group for 6 mo. CRF was evaluated using a cycle ergometer. A greater increase in relative CRF was observed in CA compared with 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 12 (CA: 1.98 vs. AA: 0.50 ml O2·kg(-1)·min (-1), P = 0.001) KKW groups. Similar effects were found in absolute CRF, with the exception of the 4-KKW (CA: 0.04 vs. AA: 0.02 l O2/min, P = 0.147) group. However, in categorical analyses, the percentages of women who improved in both relative (>0 ml O2·kg(-1)·min (-1)) and absolute (>0 l O2/min) CRF were not significantly different for CA and AA women in all exercise groups (all P > 0.05). AA postmenopausal women, in general, had an attenuated increase in CRF (both relative and absolute) following exercise training, but had similar response rates compared with CA women. Future studies should investigate the physiologic mechanisms responsible for this attenuated response.