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Effect of exercise dose on fat oxidation capacity in postmenopausal women
Author(s) -
Johannsen Neil Michael,
Edwards W. Brent,
Church Timothy S.,
Blair Steven N,
Earnest Conrad P.
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.955.22
Subject(s) - vo2 max , medicine , cohort , aerobic capacity , zoology , physical therapy , heart rate , blood pressure , biology
The capacity to oxidize fat may play an important role in health and disease. However, the effect of exercise dose on maximal fat oxidizing capacity remains unexplored. To investigate this relationship, we utilized a sub‐cohort of women (n = 260) from the DREW study (n = 464) who met stringent VO 2max criteria before and after 6 months of exercise. Women were randomly assigned to doses of exercise (kcal·kg body weight −1 ·week −1 ; KKW) at 50% VO 2max ; control (CON; n = 54), 4 KKW (n = 82), 8 KKW (n = 62), and 12 KKW (n = 62). Maximal fat oxidation (MFO; g/min) and intensity eliciting MFO (FatMax) were calculated from VO 2max data. Overall, our current sub‐cohort had similar improvements in VO 2max to those previously published by our group (trend P < 0.001). Mean (±SD) baseline MFO and relative FatMax (%) were 0.20 ± 0.06 g/min and 51.3 ± 6.3%, respectively. Neither MFO ( P = 0.93) nor FatMax (%; P = 0.51) increased with training; however, improvements in absolute FatMax (mL·kg −1 ·min −1 ) were greater after training at 8KKW (0.7 ± 1.2) and 12KKW (1.0 ± 1.1) compared with CON (0.0 ± 1.4) and 4KKW (0.1 ± 1.1; P < 0.001). In conclusion, exercise at 50% VO 2max for 6 months does not significantly improve MFO or relative FatMax. The data suggest that 50% VO 2max may not be adequate to improve MFO. Absolute FatMax data indicate that the workload during training must be constantly increased at higher doses of exercise in order to optimize fat oxidation. This research was funded by grant HL66262 from the National Institutes of Health.