https://www.selleckchem.com/products/shikonin.html ite cyclists of various disciplines, which opens opportunities for application in talent orientation and transfer. Exercise intolerance, evaluated by O2 consumption, predicts mortality in cystic fibrosis (CF). People with CF exhibit skeletal muscle dysfunctions that may contribute to an imbalance between O2 delivery and utilization. Sildenafil, a phosphodiesterase type 5 inhibitor, increases blood flow and improves O2 consumption, although the exact mechanisms in CF have yet to be elucidated. Thus, we hypothesized that exercise intolerance in CF is limited primarily by an impaired skeletal muscle O2 utilization, and sildenafil improves exercise tolerance in CF by addressing this mismatch between O2 demand and extraction. Fifteen individuals with mild to moderate CF and 18 healthy controls completed an incremental exercise test and measurements of gaseous exchange, chronotropic response, hemodynamics, and O2 extraction and utilization. People with CF also completed a 4-wk treatment with sildenafil with a subsequent follow-up evaluation after treatment. Skeletal muscle O2 extraction and utilization during exercise werk of sildenafil treatment improves the capacity of the skeletal muscle to use O2 more efficiently during exercise. Findings from the present study highlight the importance of targeting skeletal muscle O2 utilization to improve exercise tolerance in CF. This study examined one-year reliability and construct validity of survey items relating to time spent on muscle-strengthening exercise (MSE) in a subset of a large prospective cohort. Participants (N = 293 men, 433 women; age 32-73 years) were selected from the Cancer Prevention Study-3. Information was collected using a one-year pre- and post-survey and four 7-day diaries throughout the year. The pre- and post-surveys collected time spent on MSE in two ways one question captured MSE activities performed during a typical 24-hour period (24-hour survey), an