Effects of one year aerobic endurance training on resting metabolic rate and exercise fat oxidation in previously untrained men and women. Metabolic endurance training adaptations.

ABSTRACT

Although metabolic training adaptations are considered to be an important aim of recreational endurance exercise, effects of aerobic endurance training on metabolism have hardly been recorded over longer training periods. The aim of the study was therefore to record changes in resting metabolic rate (RMR), substrate oxidation at rest and maximal exercise fat oxidation rate (MFO) after one year of recreational endurance training within the ACSM-recommendations. Seventeen sedentary participants (7 male symbol/10 female symbol, 42+/-5 yr, pre-training characteristics BMI 24.6+/-2.2 kg.m (-2), VO(2max) 37.5+/-4.7 ml.min (-1).kg (-1)) completed a 12 months jogging/walking program 3 days/week for 45 min/session at a constant heart rate (HR) prescription of 60% HR-reserve. Resting measurements and maximal incremental treadmill tests were conducted before the training program, after 6 and 12 months of training. Indirect calorimetry was used to assess metabolic parameters. After 12 months of training, body weight remained unchanged ( P=0.16), however, body fat was significantly reduced by 3.4+/-2.1% ( P<0.001). Neither RMR ( P=0.42) nor substrate oxidation at rest ( P=0.25) changed significantly. MFO increased significantly over time by 0.07+/-0.08 g.min (-1) ( P<0.01) and occurred at significantly higher exercise intensities (35+/-6 vs. 44+/-15 vs. 50+/-14%VO(2max), P<0.01). In summary one year of recreational endurance training does therefore not appear to influence RMR or substrate oxidation at rest in previously untrained non-obese participants. In contrast, a constant training stimulus within the ACSM-recommendations elicits sustained improvements in MFO over at least one year of training.