Browsing by Subject "body composition"
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Item Effects of 28 Days of Beta-Alanine and Creatine Monohydrate Supplementation on Muscle Carnosine, Body Composition and Exercise Performance in Recreationally Active Females(2012-07-16) Kresta, Julie YongEarly research with beta-alanine (beta-ALA) supplementation has shown increases in muscle carnosine as well as improvements in body composition, exercise performance and blood lactate levels. Creatine monohydrate supplementation has been extensively researched for its effects on anaerobic exercise performance. Recently, a new line of studies have examined the combined effects beta-ALA and creatine supplementation on anaerobic exercise performance and lactate threshold. The purpose of the present study is to examine the acute and chronic effects of beta-ALA supplementation with and without creatine monohydrate on body composition, aerobic and anaerobic exercise performance, and muscle carnosine and phosphagen levels in college-aged recreationally active females. Thirty-two females were randomized in a double-blind placebo controlled manner into one of four supplementation groups including beta-ALA only, creatine only, beta-ALA and creatine combined and placebo. Participants supplemented for four weeks and reported for testing at baseline, day 7 and day 28. Testing sessions consisted of a resting muscle biopsy of the vastus lateralis, body composition measurements, a graded exercise test on the cycle ergometer for VO2max and lactate threshold, and multiple Wingate tests for anaerobic exercise performance. Results showed all supplementation strategies increasing muscle carnosine levels over placebo after four weeks, but not between groups. Muscle creatine increased for all groups after four weeks, but not between groups. There were improvements for all groups with body composition after four weeks, despite the present study not including a specific training protocol. There were no group differences observed for aerobic exercise, blood lactate levels, lactate threshold, ventilatory threshold, peak power, mean power, total work or rate of fatigue. There were some trends for anaerobic exercise indicating groups supplementing with creatine may have greater improvements, however, these findings were not statistically significant. The present study failed to show any additive effects of beta-ALA and creatine supplementation for body composition, aerobic exercise, lactate threshold or anaerobic exercise measures. This could be due to the small sample size resulting in low power and effect sizes. Previous research has demonstrated that four weeks of beta-ALA and creatine supplementation was enough time to increase muscle carnosine and phosphagen levels. However, perhaps more time is needed for performance adaptations to occur, especially without the addition of an exercise training component.Item Evaluation of Early Measures of Body Composition as Related to Beef Carcass Traits(2010-07-14) Maulsby, Richard Paul.Two similarly managed trials were conducted to investigate serial ultrasound measures of body composition (longissimus muscle area (ULMA), 12th - rib fat thickness (UFAT), and percentage of intramuscular fat (UIMF)) early in the lives of feeder calves as they compared to carcass traits. Group 1 cattle were Charolais-sired by Brahman-British crossbred dams whereas Group 2 cattle were purebred Beefmaster. Both groups were fed at the same commercial feedlot (Graham Land and Cattle Co.) in Gonzales, Texas. In both data sets classifications were developed for ribeye area of Lower (less than 70.95 cm2, Middle (between 70.95 cm2 and 90.3 cm2) and Upper (over 90.3 cm2) based on a range that fit within the ribeye specifications of such branded beef programs as Certified Angus Beef and Nolan Ryan?s Tender Aged Beef. Differences among ribeye area and quality grade (Choice vs. Select) categories were evaluated for ultrasound and carcass traits. As reported previously, correlations between ultrasound measures and carcass traits became larger at times closer to harvest. In both sets of cattle, there were no differences in fat thickness or intramuscular fat at the ultrasound scan sessions or in these carcass traits due to ribeye area category. The same trend for quality grade classification was not seen across both groups of cattle however. In Group 1, there were no differences in early measures of body composition between carcass quality grade classes except for ultrasound fat thickness at weaning. However, in Group 2 cattle there were differences in ultrasound fat at times 1 and 2, IMF at time 1, and ribeye area at time 2 between cattle that graded choice verses those that graded select. Correlations between ultrasound measures of REA (r of .26 to .50) and ultrasound REA and carcass REA (r of .16 to .81) appeared to be lower in Group 1 vs. Group 2 (r of .55, and .64 to 81 respectively). Results from this project imply that changes in ribeye area will not automatically result in changes of marbling and vice versa. Furthermore, these results also show that ultrasound is useful to help predict beef carcass traits, but that early measures of body composition used alone do not explain a large portion of the variation in the carcass measures and specific methods should be developed by different biological cattle types.Item Variation in energy expenditures between growing steers with divergent residual feed intakes(Texas A&M University, 2006-04-12) White, Monte Blaine IIIObjectives of this study were to determine if variation in energy expenditures contributed to differences in feed efficiency between low and high RFI steers. Nine steers with the lowest and highest residual feed intakes (RFI) were selected from 169 Braunvieh-sired crossbred steers that were individually fed a pelleted roughage-based diet for 77 d. Following the RFI measurement period, heat production (HP) measurements were obtained using indirect calorimetry while steers were fed the same roughage diet (RD) and on a high-concentrate diet (CD). Linear regression analyses of log HP or retained energy on ME intake were used to determine energy partitioning. Motion and lying activity were measured concurrently with HP on the RD and CD. During the RFI measurement period, low RFI steers had lower (P < 0.01) RFI (-1.7 vs. 1.6 ?? 0.17 kg/d), DMI (7.7 vs. 10.2 ?? 0.42 kg/d) and feed:gain ratio (F:G; 7.2 vs. 10.6 ?? 0.60), but similar final BW and ADG compared to high RFI steers. However, there were smaller differences in DMI (8.4 vs. 9.7 ?? 0.38 kg/d; P < 0.05; 7.56 vs. 8.16 ?? 0.31; P = 0.19) and F:G (10.0 vs. 10.9 ?? 0.40; P = 0.36; 6.5 vs. 7.5 ?? 0.30; P < 0.05) between low and high RFI steers, on the RD and CD, respectively. ME for maintenance (MEm; kg .75 d??1) and the partial efficiencies of ME used for maintenance and gain were similar for low and high RFI steers. Likewise, no differences were found in fasting HP or fed HP. Motion activity was lower (P < 0.05) for low RFI steers compared to high RFI steers during fasting HP. Covariate analysis of HP at the same activity level yielded similar results. At slaughter, weights of lung and trachea (P < 0.05), spleen (P < 0.05) and adrenal gland (P = 0.07) were higher for low RFI cattle. The lack of differences in energy partitioning between divergent RFI steers may have been the result of alterations in feeding behavior or stress imposed by adapting steers to calorimetry chambers.