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.
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.
Study Type
OBSERVATIONAL
Enrollment
80
Centro de Estudios, Investigación y Medicina del Deporte
Pamplona, Navarre, Spain
Time spent in moderate-to-vigorous physical activities
The time spent in moderate-to-vigorous physical activities during a week (The participants have to wear an accelerometer attatched at the hip on an elastic belt for a period of 7 days)
Time frame: 1 week
accelerometer intensity cut-points
accelerometer activity counts corresponding to each woman´s lactate thresholds will determine each intensity level (These thresholds are determined on the walking-running tests performed on different days with a minimum of one week in between. These tests are independent, they are performed at constant speed during 20min to determine the highest speed at which the lactate concentration remains in a steady state between the minute 10 and 20 of the test)
Time frame: an average of 1 month
Number of vertical acceleration peaks during the day
raw acceleration data will be measured to describe daily exposure to potentially osteogenic vertical impacts (The participants have to wear an accelerometer attatched at the hip on an elastic belt for a period of 7 days)
Time frame: 1 week
aerobic fitness
determination of the speeds corresponding to the lactate thresolds during the walking-running test
Time frame: an average of 1 month
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