J. A. Woods

Effects of carbohydrate feedings on plasma free tryptophan and branched-chain amino acids during prolonged cycling

SummaryBrain serotonin (5-hydroxytryptamine, 5-HT) has been suggested to be involved in central fatigue during prolonged exercise. Changes in the ratio of plasma free tryptophan (free Trp) to branched-chain amino acids (BCAA) are associated with altered brain 5-HT synthesis. The purposes of this study were to describe systematically the effects of prolonged exercise on changes in plasma free Trp and BCAA and to examine the effects of carbohydrate (CHO) feedings on these same variables. Eight well-trained men [n

Effects of exercise on the immune response to cancer

dot V{text{O}}_{text{2}}

Effects of exercise on macrophage activation for antitumor cytotoxicity

nmax = 57.8 (SE 4.1) ml kg−1 min−1] cycled for up to 255 min at a power output corresponding toVO2 at lactate threshold (approximately 68%VO2max) on three occasions separated by at least 1 week. Subjects drank 5 ml kg−1 body wt−1 of either a water placebo, or a liquid beverage containing a moderate (6% CHO) or high (12% CHO) concentration of carbohydrate beginning at min 14 of exercise and every 30 min thereafter. Exercise time to fatigue was shorter in subjects receiving placebo [190 (SE 4) min] as compared to 6% CHO [235 (SE 10) min] and 12% CHO [234 (SE 9) min] (P<0.05). Glucose and insulin decreased in the placebo group, and free Trp, free-Trp/BCAA, and free fatty acids increased approximately five- to sevenfold (P < 0.05). These changes were attenuated in a dose-related manner by the carbohydrate drinks. Plasma free Trp and plasma free fatty acids were highly correlated (r=0.86,P<0.001). Plasma BCAA did not change in the placebo group, but decreased slightly in those receiving 6% CHO and 12% CHO (P<0.05). No differences in heart rate,n

Correlates to Performance on Field Tests of Muscular Strength

dot V{text{O}}_{text{2}}

684 MECHANISMS INVOLVED IN EXERCISE-INDUCED INCREASES IN MACROPHAGE ANTI-TUMOR CYTOTOXICITY (CYTX)

n, plasma volume and respiratory exchange ratio were found. The results indicate that free Trp and free Trp/BCAA increase progressively during prolonged cycling to fatigue. This response was attenuated by CHO feedings. Changes in plasma free fatty acids probably play a prominent role in these responses.

Effects of Exercise on the Immune Response to Cancer: 384

The purpose of this study was to determine the validity of five field tests (FTs) of upper body muscular strength and endurance (UBMSE) in 9-10-year-old children. Ninety-four children (38 boys, 56 girls) performed five FTs of UBMSE: pull-ups, flexed arm hang, push-ups, Vermont modified pull-ups (VMPU), and New York modified pull-ups. They also performed three criterion tests (CTs) of strength and three CTs of muscular endurance using a supported weight, set-resistance device. Zero-order correlations between the sum of the standard scores on the three CTs of strength (SUM1RM) and the FTs were nonsignificant. However, when SUM1RM was expressed relative to body weight (SUM1RM.kg-1), significant (p < .01) correlation coefficients were obtained for each FT. Highest correlations with SUM1RM.kg-1 were observed for the VMPU, and this same test yielded the smallest percentage of zero scores. Principal components analysis of the CTs, normalized for body weight, and FTs yielded a factor on which both the FTs and CTs of strength loaded significantly. These data indicate that the five FTs, though invalid as measures of absolute strength and muscular endurance, manifest concurrent and construct validity as measures of weight-relative muscular strength.