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01.03.2012 | Original Article | Ausgabe 3/2012

European Journal of Applied Physiology 3/2012

Exercise intensity and oxygen uptake kinetics in African-American and Caucasian women

Zeitschrift:
European Journal of Applied Physiology > Ausgabe 3/2012
Autoren:
Nicola Lai, Fatima Tolentino-Silva, Melita M. Nasca, Marco A. Silva, L. Bruce Gladden, Marco E. Cabrera
Wichtige Hinweise
Communicated by Susan A. Ward.
M.E. Cabrera died February 5, 2009.

Abstract

The effect of exercise intensity on the on- and off-transient kinetics of oxygen uptake (VO2) was investigated in African American (AA) and Caucasian (C) women. African American (n = 7) and Caucasian (n = 6) women of similar age, body mass index and weight, performed an incremental test and bouts of square-wave exercise at moderate, heavy and very heavy intensities on a cycle ergometer. Gas exchange threshold (LTGE) was lower in AA (13.6 ± 2.3 mL kg−1 min−1) than C (18.6 ± 5.6 mL kg−1 min−1). The dynamic exercise and recovery VO2 responses were characterized by mathematical models. There were no significant differences in (1) peak oxygen uptake (VO2peak) between AA (28.5 ± 5 mL kg−1 min−1) and C (31.1 ± 6.6 mL kg−1 min−1) and (2) VO2 kinetics at any exercise intensity. At moderate exercise, the on- and off- VO2 kinetics was described by a monoexponential function with similar time constants τ 1,on (39.4 ± 12.5; 38.8 ± 15 s) and τ 1,off (52.7 ± 10.1; 40.7 ± 4.4 s) for AA and C, respectively. At heavy and very heavy exercise, the VO2 kinetics was described by a double-exponential function. The parameter values for heavy and very heavy exercise in the AA group were, respectively: τ 1,on (47.0 ± 10.8; 44.3 ± 10 s), τ 2,on (289 ± 63; 219 ± 90 s), τ 1,off (45.9 ± 6.2; 50.7 ± 10 s), τ 2,off (259 ± 120; 243 ± 93 s) while in the C group were, respectively: τ 1,on (41 ± 12; 43.2 ± 15 s); τ 2, on (277 ± 81; 215 ± 36 s), τ 1,off (40.2 ± 3.4; 42.3 ± 7.2 s), τ 2,off (215 ± 133; 228 ± 64 s). The on- and off-transients were symmetrical with respect to model order and dependent on exercise intensity regardless of race. Despite similar VO2 kinetics, LTGE and gain of the VO2 on-kinetics at moderate intensity were lower in AA than C. However, generalization to the African American and Caucasian populations is constrained by the small subject numbers.

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