Are there differences in performance, metabolism, and quadriceps muscle activity in black African and Caucasian athletes during brief intermittent and intense exercise?

The purpose of the present study was to determine whether there are any differences in power output (PO) and/or quadriceps muscle (Quad) activity between black African and Caucasian football players during a force-velocity (fv) exercise test, which consisted of performing maximal 6-s sprints against an increasing load. Each subject started the test with a load of 2 kg and then recovered for 5 min before repeating the same test with a load increased by 2 kg. When the pedal frequency did not exceed 130 rev·min–1, the load was increased by only 1 kg. Each subject attained the load corresponding to his maximal power if an additional increase in load (+1 kg) induced a power decrease. Nine black Africans (mean age 24.2 ± 3.3 years) and nine Caucasians (24.7 ± 4.2 years) (matched for stature and aerobic fitness) participated in the fv exercise test. During the test, PO, blood lactate, and the quadriceps electromyography (EMG) root mean square (Quad RMS) were assessed. Higher blood lactate was observed in Caucasians than in black Africans for POs over the load range from 4 kg up to the maximal power. However, PO and Quad RMS values were similar in Caucasians and black Africans. They also had similar lean leg volume (LLV) and consequently produced similar PO/LLV and Quad RMS/LLV values. Overall, our results suggest that Caucasians and black Africans matched for stature, max, and training background have similar PO and Quad RMS values, but different blood lactate concentrations during brief, intermittent, intense exercise performed on a cycloergometer

Low cardiorespiratory fitness in African Americans: a health disparity risk factor?

Low cardiorespiratory fitness (CRF) is a well-established risk factor for all-cause and cardiovascular disease mortality. African Americans have higher rates of cardiovascular disease compared with their Caucasian counterparts. However, the extent to which lower CRF levels contribute to the excess risk in African Americans has not been fully explored. The purpose of this review is to: (i) explore the literature evaluating the relationship between CRF and mortality specifically in African American populations; and (ii) critically evaluate the studies which have compared CRF between African American and Caucasians in epidemiological studies and clinical trials. We have further discussed several potential mechanisms that may contribute to the observation of lower CRF levels in African American compared with Caucasian adults, including potential racial differences in physical activity levels, muscle fiber type distribution, and hemoglobin levels. If lower CRF is generally present in African Americans compared with Caucasians, and is of a clinically meaningful difference, this may represent an important public health concern