Browsing by Subject "Resistance training."
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Item A comparison of the effects of ursolic acid and L-leucine supplementation on markers of muscle protein synthesis via Akt-mTOR signaling response to resistance exercise.(2014-09-05) Church, David D.; Willoughby, Darryn Scott, 1963-; Health, Human Performance and Recreation.; Baylor University. Dept. of Health, Human Performance and Recreation.Resistance exercise (RE) stimulates skeletal muscle protein synthesis (MPS) during post-exercise recovery due to up-regulation of the mammalian target of rapamycin (mTOR) signaling pathway L-leucine supplementation is also known to stimulate MPS by activating mTOR signaling. However, recent research has discovered a natural compound called ursolic acid which also appears to stimulate MPS by activating the mTOR signaling pathway, and has been presumed to occur due to IGF-1 receptor (IGF-1R) up-regulation. Ursolic acid is a natural pentacyclic triterpenoid carboxylic acid that is widely found in apple skin and other fruits such as cranberries. The main purpose of this study was to compare the effects of a single dose of ursolic acid or L-leucine supplementation given immediately after resistance exercise on IGF-1 (a serum regulator of MPS) and the subsequent effects of IGF-1 on phosphorylating/activating its receptor (IGF-1R^Tyr1131). Furthermore, the purpose was to also determine the effects on signaling intermediates of MPS contained within the Akt/mTOR pathway (phosphorylated levels of Akt^Thr308, mTOR^Ser2448, p70S6K^Thr389). In a randomized, cross-over design, nine apparently healthy, resistance-trained [regular, consistent resistance training (i.e. thrice weekly) for at least 1 year prior to the onset of the study], men between the ages of 18-30 performed three separate testing sessions of lower-body resistance exercise involving 4 sets of 8-10 repetitions at 75-80% 1-RM on the angled leg press and knee extension exercises. Immediately after each resistance exercise session, participants orally ingested 3 grams (0.043 g/kg equivalent) of cellulose placebo (PLC), L-leucine (LEU), or ursolic acid (UA). A venous blood sample was obtained before, and 0.5, 2, and 6 hr post-exercise, whereas a vastus lateralis muscle biopsy was obtained before and 2 and 6 hr post-exercise. Each testing session was separated by 7 days to allow full recovery between sessions. Statistical analyses were performed utilizing separate two-way ANOVA for each criterion variable employing a probability level of ≤ 0.05. Using ELISA, no significant differences were observed among the three supplements for serum IGF-1 (p> 0.05). Also using ELISA, for skeletal muscle phosphoproteins, no significant differences existed among the three supplements for phosphorylated IGF-1R, Akt, and p70S6K (p> 0.05). However, the LEU supplement significantly increased phosphorylated mTOR compared to UA and PLC (p= 0.001). At the 3 g dose provided, ursolic acid was unable to increase IGF-1R signaling and, unlike L-leucine, ursolic acid had no positive effect on mTOR signaling activity. Therefore, ursolic acid appears to have no effect on mTOR activity when ingested immediately following resistance exercise.Item Determining related work-to-rest ratios following a maximal effort isokinetic leg extension bout in trained and untrained males : a double-blind creatine/placebo controlled study.(2010-02-02T20:02:01Z) Parker, Adam G.; Greenwood, Mike.; Health, Human Performance and Recreation.; Baylor University. Dept. of Health, Human Performance and Recreation.Purpose: A single 30 second bout of high intensity isokinetic exercise is capable of depleting available skeletal muscle Phosphocreatine (PCr) and adenosine triphosphate (ATP). Within several minutes the body is able to replenish those stores to facilitate further muscular activity. There have been suggested work-to-rest ratios to allow for the optimal recovery period to achieve repletion of the intramuscular PCr and ATP. This study attempted to determine how training status and supplementation with creatine monohydrate (CM) may affect this process. Methods: Subjects in the CM group consumed 20 g of CM (four 5 g doses/day), while subjects in the placebo group consumed 20 g of dextrose (four 5 g doses/day). Five (pre-supplementation, pre-exercise, immediate post exercise, 3 min. post exercise, and 5 min. post exercise) muscle samples were taken from the vastus lateralis of the dominant leg of 32 males [16 resistance trained (8 each receiving CM or placebo), 16 untrained (8 each receiving CM or placebo)]. Samples were measured for Cr, PCr, ATP, glycogen, and lactate, and TCr was calculated by adding Cr and PCr at all time points. Blood lactate was measured via finger prick prior to and 5 minutes after the exercise bout. Results: Subjects consuming CM increased muscle total creatine content by 10.2%. Neither CM supplementation nor resistance training status significantly affected PCr or ATP repletion rates. Trained subjects had significantly (p >.05) higher muscle glycogen content. Trained individuals maintained non-significantly higher muscle ATP and PCr after and at all time points during recovery from the exercise bout compared to untrained individuals. At both 3 and 5 minutes after exercise, none of the groups were able to fully restore resting levels of muscle ATP or PCr. Conclusions: The results indicate that CM and training status did not significantly enhance repletion rates of muscle ATP or PCr. Further, 5 minutes of rest was not long enough to fully recover muscular ATP and PCr content.Item The effects of a 12-week resistance training program combined with casein or whey protein supplementation on body composition, muscle strength, and markers of satellite cell activation in older males.(2010-10-08T16:12:13Z) Allison, Annie G.; Cooke, Matthew B.; Health, Human Performance and Recreation.; Baylor University. Dept. of Health, Human Performance and Recreation.Resistance training and protein supplementation have been shown to increase muscle mass and strength, and thus may be an effective method to combat muscle wasting (sarcopenia) that occurs with aging. Thirty-six males (62.5 yrs, 177 cm and 95.25 kg) were randomly assigned to ingest either whey isolate protein, casein protein or carbohydrate while participating in a 12-week high intensity resistance training program. Resistance training increased both upper and lower body strength, body mass and lean muscle mass while decreasing body fat percentage. However, no effects from training were observed on serum anabolic hormones and indirect markers of satellite cell activation. A trend towards significantly higher lower body strength was observed in the whey isolate (p=0.053) and casein (p=0.086) groups, respectively, compared to carbohydrate placebo group. The present study suggests protein supplementation in conjunction with high intensity resistance training may be important in combating sarcopenia.