Lifestyle. . . Loss In Addition To GPX4
1984; Jequier & Flatt, 1986). We defined the underlying efficiencies using three individual determinations, as follows: (1) selleck exercise efficiency (i.e. delta efficiency) determined from power output and oxygen uptake measured during a cycle ergometer test; (2) a simple method for estimating contractile-coupling efficiency of the quadriceps in vivo; and (3) mitochondrial-coupling efficiency based on a combination of in vivo and biopsy determinations (Conley et al. 2000b). The new insight from this pairing of experiments with analysis is the important role of mitochondrial-coupling efficiency in the decline in exercise efficiency in the elderly. This new analysis uses magnetic resonance measurements reported by Conley et al. (2000b) and cycle ergometer results reported by Conley et al. (2000a). The leg power output values have not been previously reported. All subjects voluntarily gave informed, written consent, and the study was approved by the University of Washington Human Subjects Review Committee in conformity with the latest revision of the Declaration of Helsinki for treatment of human subjects. The characteristics of the subjects were reported in a previous paper (Conley et al. 2000b). Briefly, the adult group consisted of nine subjects (six males and three females; mean �� SD age, 38.8 �� 7.5 years) and the elderly group consisted of 39 subjects (17 male and 22 female; mean �� SD age, 68.8 �� 2.4 years). www.selleckchem.com/products/azd9291.html Subjects completed maximal cycle ergometry (Medgraphics CPE 2000, St Paul, MN, USA) to obtain values for maximal oxygen uptake () and the corresponding values for leg power output (Pmax), respiratory exchange ratio (RERmax) and heart rate (HRmax) at . The protocol consisted of a brief familiarization on the cycle and a 1 min pre-exercise period, during which resting metabolic data were collected. A 1 min period of unloaded GPX4 cycling was next and then at min 2 the ramp increase in workload began at a fixed rate of 10, 12 or 14 W min?1. The rate was chosen based on the subject's reported fitness level and body mass. The tests were completed within 7�C15 min. Subjects maintained a constant pedalling rate of 60 r.p.m. For the elderly subjects, a physician continuously oversaw a 12-lead electrocardiogram (Quinton 650, Seattle, WA, USA) to monitor heart rate and any cardiac abnormalities during the test. Blood pressure was measured manually every 2 min during the exercise. Criteria for test termination included subject fatigue, signs and symptoms of exercise intolerance, electrocardiogram changes and abnormal blood pressure or respiratory response, in accordance with American College of Sports Medicine guidelines (ACSM, 1991). Details concerning the gas and lactate analysis, as well as the reproducibility of the physiological measures, have already been published (Conley et al. 2000a).
