Energy system contributions during incremental exercise test

The main purpose of this study was to determine the relative contributions of the aerobic and glycolytic systems during an incremental exercise test (iet). ten male recreational longdistance runners performed an iet consisting of three-minute incremental stages on a treadmill. the fractions of the contributions of the aerobic and glycolytic systems were calculated for each stage based on the oxygen uptake and the oxygen energy equivalents derived by blood lactate accumulation,respectively. total metabolic demand (wtotal) was considered as the sum of these two energy systems. the aerobic (waer) and glycolytic (wglycol) system contributions were expressed as a percentage of the wtotal. the results indicated that waer(86-95%) was significantly higher than wglycol(5-14%) throughout the iet (p < 0.05). in addition,there was no evidence of the sudden increase in wglycolthat has been previously reported to support to the anaerobic threshold concept. these data suggest that the aerobic metabolism is predominant throughout the iet and that energy system contributions undergo a slow transition from low to high intensity. © journal of sports science and medicine (2013).