This observational study aims to accurately assess weekly physical activity levels of postmenopausal women using lactate thresholds to individualize the accelerometer cut-points.~Postmenopausal women will be recruited from local advertisements in public health centers. Each woman will perfom on different days a progressive discontinuous submaximal walking-running test and several constant speed tests wearing an accelerometer to identify the individual lactate threshold (LT), the maximal lactate steady state (MLSS) and the corresponding accelerometer activity counts/min (cpm). Participants then will wear an actigraph accelerometer (wGT3X-BT) for seven days.~Linear regression equations will be developed for each participant to determine accelerometer activity counts for each intensity level: 1) sedentary behaviour (<200 cpm), 2) light intensity (200 cpm to activity counts at LT), 3) moderate intensity (activity counts between LT and MLSS) and 4) vigorous intensity (activity counts >MLSS). Physical activity levels will be measured using both, individualized approach and Sasaki, Jonh and Freedson´s (2011) absolute cut-points obtained through walking and running activities eliciting 3-6 MET intensities (2689-6166 cpm), considering it a moderate effort.
The purpose of this study is to accurately assess weekly physical activity levels of postmenopausal women using lactate thresholds to individualize the accelerometer cut-points.