Biomedical subjects

B C Ruby

Publications and source records attributed to B C Ruby.

4 recordsLinked to original sources

PubMed1997

Role of hope in academic and sport achievement.

Hope is the sum of goal thoughts as tapped by pathways and agency. Pathways reflect the perceived capability to produce goal routes; agency reflects the perception that one can initiate action along these pathways. Using trait and state hope scales, studies explored hope in college student athletes. In Study 1, male and female athletes were higher in trait hope than nonathletes; moreover, hope significantly predicted semester grade averages beyond cumulative grade point average and overall self-worth. In Study 2, with female cross-country athletes, trait hope predicted athletic outcomes; further, weekly state hope tended to predict athletic outcomes beyond dispositional hope, training, and self-esteem, confidence, and mood. In Study 3, with female track athletes, dispositional hope significantly predicted athletic outcomes beyond variance related to athletic abilities and affectivity; moreover, athletes had higher hope than nonathletes.

Achievement↗

PubMed1997

Effects of estradiol on substrate turnover during exercise in amenorrheic females.

The purpose of this investigation was to determine the effects of transdermal estradiol (E2) replacement on substrate utilization during exercise. Amenorrheic females (N = 6) performed three exercise trials following 72 h of placebo (C 72) and 72 and 144 h of medicated transdermal estradiol (E2) treatment (E2 72 and E2 144). Exercise involved 90 min of treadmill running at 65% VO2max followed by timed exercise to exhaustion at 85% VO2max. Resting blood samples were obtained for glucose, insulin, free fatty acids (FFA), and E2. Exercise blood samples were obtained for E2, lactate, epinephrine, and norepinephrine. Rates of appearance and disposal were calculated for glucose and glycerol using a primed, continuous infusion of [6,6-2H] glucose and [2H5] glycerol. Medicated transdermal placement increased E2 significantly at rest, before exercise (35.03 +/- 12.3, 69.5 +/- 20.1, and 73.1 +/- 31.6 pg.mL-1 for the C 72, E2 72, and E2 144 trials, respectively, P < 0.05). Resting FFA increased significantly following E2 treatment (0.28 +/- 0.16, 0.41 +/- 0.27, and 0.40 +/- 0.21 mmol.L-1 for the C 72, E2 72, and E2 144 trials, respectively, P < 0.05). Glucose Ra was significantly decreased during exercise as a result of E2 replacement (21.9 +/- 7.7, 18.9 +/- 6.2, and 18.9 +/- 5.6 mumol.kg-1.min-1 for the C 72, E2 72, and E2 144 trials, respectively, P < 0.05). Average glucose Rd also decreased during exercise as a result of E2 replacement (21.3 +/- 7.8, 18.5 +/- 6.4, and 18.6 +/- 5.8 mumol.kg-1.min-1 for the C 72, E2 72, and E2 144 trials, respectively, P < 0.05). However, the estimated relative contribution of plasma glucose and muscle glycogen to total carbohydrate oxidation was similar among the trials. Epinephrine values were significantly lower late in exercise during the E2 72 and E2 144 trials, compared with the C 72 trial (P < 0.05). These results indicate that elevated E2 levels can alter glucose metabolism at rest and during moderate intensity exercise as a result of decreased gluconeogenesis, epinephrine secretion, and/or glucose transport.

Administration, Cutaneous↗

PubMed1997

Effects of deep water and treadmill running on oxygen uptake and energy expenditure in seasonally trained cross country runners.

OBJECTIVE: The purpose of this study was to physiologically compare submaximal intensity deep water running (DWR) and treadmill running (TMR) exercise in trained athletes. EXPERIMENTAL DESIGN: Pre-test, post-test, 2 x 2 factoral design. SETTING: Treadmill exercise tests occurred in the Human Performance Laboratory. DWR trials took place in the deep end of the University pool. PARTICIPANTS: Seasonally trained college-aged male cross country runners (N = 8). Subjects completed a treadmill maximal oxygen consumption (VO2max) test, followed by a submaximal treadmill and deep water run at heart rates equivalent to 60% and 80% treadmill VO2max. MEASURES: Oxygen consumption (VO2), ventilation (VEstpd), rates of perceived exertion (RPE), energy expenditure (kcal.min-1), respiratory exchange ratio (RER), fat and carbohydrate oxidation (g.min-1) were measured during two 5 minute steady state stages for both trials. RESULTS: The trial by intensity interaction for VEstpd was significant, demonstrating greater ventilation during DWR as compared to TMR at 80% VO2max. The main effect of trial demonstrated that significantly higher RER and carbohydrate oxidation, and lower fat oxidation occurred during DWR as compared to TMR. VO2, RPE, and energy expenditure did not differ significantly between trials. CONCLUSIONS: DWR is a comparable form of submaximal intensity exercise as TMR in well-trained athletes. DWR does, however, maintain unique properties that differs it from TMR. Therefore, the concept of training specificity should be further considered when prescribing DWR and using it as an enhancement tool or substitute for dry land running.

Adipose Tissue↗

PubMed1994

Gender differences in substrate utilisation during exercise.

The selection and utilisation of metabolic substrates during endurance exercise are regulated by a complex array of effectors. These factors include, but are not limited to, endurance training and cardiorespiratory fitness, exercise intensity and duration, muscle morphology and histology, hormonal factors and diet. Although the effects of these factors on substrate utilisation patterns are well understood, the variation in substrate utilisation during endurance exercise between males and females is not. Because of the extreme heterogeneity in exercise protocols and individuals studied, the differences in substrate utilisation between males and females remain somewhat inconclusive. Regardless of heterogeneity, if the results from studies are interpreted collectively, an apparent gender difference in the selection and metabolism of substrates can be seen in sedentary individuals. However, this difference between genders diminishes as the level of cardiorespiratory fitness is increased to that of highly trained individuals. During rest and lower intensity exercise, the preferential metabolism of lipid occurs with a concomitant sparing of muscle glycogen. However, as the intensity of exercise is increased, the relative contribution of carbohydrate also increases. The exercise intensity at which the shift from lipid to carbohydrate is determined and regulated by the previously mentioned factors. Because the intensity and duration of exercise play a predominant role, the variation in exercise protocols poses a methodological concern when interpreting previous research. When attempting to compare the metabolism of substrates during endurance exercise, appropriate selection and interpretation of measurement techniques are necessary. Measurement techniques include the nonprotein respiratory exchange ratio, muscle and fat biopsies and the measurement of various blood metabolites, such as free fatty acids and glycerol. Similarly, in vitro analysis of lipolytic activity has also been demonstrated in males and females in response to varying levels of female gonadotrophic hormones. When comparing the substrate utilisation patterns between males and females, the area of hormonal regulation has received less attention. Often the catecholamine response to endurance exercise is measured; however, the gonadotrophic hormones, particularly those of the female, have received less attention when comparing genders. Indeed, the regulatory nature of the female gonadotrophic hormones has been demonstrated. Collectively, the effects of elevated estrogen, as in the luteal phase of menstruation, appear to promote lipolytic activity. Estrogen-mediated lipolytic activation occurs by apparently altering the sensitivity to lipoprotein lipase and by increasing the levels of human growth hormone (somatotropin), an activator of lipolysis.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗