The Effects of Branched-Chain Amino Acid Supplementation on Indirect Indicators of Muscle Damage and Performance

The purpose of this study was to determine whether branched-chain amino acid (BCAA) supplementation attenuates indirect indicators of muscle damage, lowers ratings of perceived exertion, and improves aerobic performance as compared to an isocaloric, carbohydrate (CHO) beverage or a non-caloric placebo beverage. Nine, untrained males (VO2 max 36.26 2.23 ml/kg/min) performed three 90-minute cycling bouts at 55% VO2 max followed by a 15-minute time trial. Metabolic data was collected every 15 minutes during the steady-state ride, and indirect muscle damage markers were assessed pre, post, 4-hours, 24-hours, and 48-hours post-exercise. Pre and post-exercise concentrations of the BCAA and glucose were also recorded. All blood markers were adjusted for plasma volume shifts.There were no differences in dietary intake between trials for 3 days prior to exercise. Creatine kinase concentrations were significantly lower after the BCAA trial as compared to the placebo trial at 4, 24, and 48-hours post-exercise, as well as the CHO beverage at 24-hours post-exercise. Creatine kinase was lower in the CHO trial at the 24- and 48-hour time points as compared to the placebo trial. Lactate dehydrogenase concentrations were elevated in the placebo trial at 4-hours as compared to the BCAA trial. As compared to the alternate trials, ratings of perceived soreness were lower at 24-hours post-exercise, leg flexion torque was higher at the 48-hour time point, and plasma concentrations of the BCAA were elevated following the BCAA trial. Time-trial performance was improved in the CHO trial, and ratings of perceived exertion were lower at 75 and 90-minutes of exercise in the BCAA trial as compared to the placebo trial. There were no significant condition x time differences for leg extension torque, VO2, ventilation, heart rate, RER, or energy expenditure. In addition, there was no order effect for creatine kinase, lactate dehydrogenase, leg flexion/extension torque, ratings of perceived soreness, or time trial performance. The present data suggest that BCAA supplementation attenuates muscle damage during prolonged endurance exercise in unfit, college-aged males, but does not affect time trial performance. CHO ingestion improves time trial performance and attenuates post-exercise creatine kinase levels at 24-hours post-exercise as compared to a placebo beverage

Acute Effects of Plyometric and Resistance Training on Running Economy in Trained Runners

Results regarding the acute effects of plyometric and resistance training (PRT) on running economy (RE) are conflicting. Eight male collegiate distance runners (21 +/- 1 years, 62.5 +/- 7.8 ml/kg/min V[Combining Dot Above]O2 peak) completed V[Combining Dot Above]O2 peak and 1 repetition maximum (1RM) testing. Seven days later, subjects completed a 12 minute RE test at 60% and 80% V[Combining Dot Above]O2 peak, followed by a PRT protocol or a rested condition of equal duration (CON). The PRT protocol consisted of 3 sets of 5 repetitions at 85% 1RM for barbell squats, Romanian deadlifts, and barbell lunges; the same volume was utilized for resisted lateral lunges, box jumps, and depth jumps. Subjects completed another RE test immediately following the treatments as well as 24 hours later. Subjects followed an identical protocol six days later with condition assignment reversed. RE was determined by both relative V[Combining Dot Above]O2 (ml/kg/min) as well as energy expenditure (kcal/min). There was a significant (p \u3c 0.05) between-trial increase in V[Combining Dot Above]O2 (37.1 +/- 4.2 ml/kg/min PRT vs. 35.5 +/- 3.9 ml/kg/min CON) and energy expenditure (11.4 +/- 1.3 kcal/min PRT vs. 11.0 +/- 1.4 kcal/min CON) immediately post-PRT at 60% V[Combining Dot Above]O2 peak, but no significant changes were observed at 80% V[Combining Dot Above]O2 peak. Respiratory exchange ratio (RER) was significantly (p \u3c 0.05) reduced 24 hours post-PRT (0.93 +/- 0.0) as compared to the CON trial (0.96 +/- 0.0) at 80% V[Combining Dot Above]O2 peak. Results indicate that high intensity PRT may acutely impair RE in aerobically trained individuals at a moderate running intensity, but that the attenuation lasts less than 24 hours in duration

Reliability of BOD POD Measurements Remain High Following a Short Duration Low-Carbohydrate Diet

The purpose of the present study was to determine whether expected changes in body weight via a three day low-carbohydrate (CHO) diet will disrupt the reliability of air displacement plethysmography measurements via BOD POD. Twenty-four subjects recorded their typical diets for three days prior to BOD POD and seven-site skinfold analyses. Subjects were matched for lean body mass and divided into low-CHO (LC) and control (CON) groups. The LC group was given instruction intended to prevent over 50 grams/day of carbohydrate consumption for three consecutive days, while the CON group replicated their previously recorded diet. Body composition measurements were repeated post-dietary intervention. Test -retest reliability measures were significant (p \u3c 0.01) and high for body fat percentage in both the LC and CON groups (r = 0.993, 0.965, respectively). Likewise, skinfold analysis for body fat percentage reliability was high in both groups (r = 0.996, 0.997, respectively). There were significant differences between first and second BOD POD measurements for body mass (72.9 ± 13.3 vs. 72.1 ± 13.0 kg) and body volume (69.0 ± 12.7 to 68.1 ± 12.2 L) in the LC group (p \u3c 0.05). However, there were no differences (p \u3e 0.05) in BOD POD-determined body fat percentage, lean body mass, or fat mass between the first and second trial in either groups. Body composition measures via BOD POD and seven-site skinfolds remain reliable after three days of a LC diet despite significant decreases in body mass

Twelve Week Calcium Collagen Chelate or Calcium plus Vitamin D Supplementation Does Not Affect Bone Metabolism in Trained Cyclists

The purpose of the present study was to determine whether 12 weeks of calcium collagen chelate (CCC) supplementation during habitual training would affect body composition, bone mineral density (BMD), and biomarkers of bone metabolism in competitive cyclists. Twenty trained (maximal aerobic capacity \u3e 50 ml/kg/min, mean training volume: 28 h/wk) male cyclists performed maximal exercise testing and 40-km time trials (TT) on an electronically braked cycle ergometer. BMD of the whole body, lumbar spine (L1-L4), and both hips were measured via dual-energy X-ray absorptiometry (DXA). The cyclists were assigned to one of two groups: 1) 6 g/d of CCC with 600 mg calcium and 400 IU vitamin D or 2) a placebo control (CON) composed of an inert compound with equivalent calcium and vitamin D concentrations to CCC. Two-way repeated measures ANOVA and Pearson product-moment correlations were used to determine the effects of CCC or CON supplementation on BMD, bone alkaline phosphatase (BAP), tartrate resistant acid phosphatase 5b (TRAP5b), and sclerostin (SCL); significance was accepted at p \u3c 0.05. No within- or between-group differences in dependent variables were found. Significant correlations were found between weekly training volume and TRAP5b (r = 0.531), BAP and VO2 max (r = -0.561), and BAP/TRAP5b ratio and both right/left hip BMD (r = -0.649 and r = -0.646, respectively). In conclusion, 12 weeks supplementation of CCC does not affect body composition, BMD, or biomarkers of bone metabolism in trained, competitive cyclists in comparison to equivalent amounts of calcium plus vitamin D

Effect of Carbohydrate-Protein Supplement Timing on Acute Exercise-Induced Muscle Damage

Purpose: To determine if timing of a supplement would have an effect on muscle damage, function and soreness. Methods: Twenty-seven untrained men (21 ± 3 yrs) were given a supplement before or after exercise. Subjects were randomly assigned to a pre exercise (n = 9), received carbohydrate/protein drink before exercise and placebo after, a post exercise (n = 9), received placebo before exercise and carbohydrate/protein drink after, or a control group (n = 9), received placebo before and after exercise. Subjects performed 50 eccentric quadriceps contractions on an isokinetic dynamometer. Tests for creatine kinase (CK), maximal voluntary contraction (MVC) and muscle soreness were recorded before exercise and at six, 24, 48, 72, and 96 h post exercise. Repeated measures ANOVA were used to analyze data. Results: There were no group by time interactions however, CK significantly increased for all groups when compared to pre exercise (101 ± 43 U/L) reaching a peak at 48 h (661 ± 1178 U/L). MVC was significantly reduced at 24 h by 31.4 ± 14.0%. Muscle soreness was also significantly increased from pre exercise peaking at 48 h. Conclusion: Eccentric exercise caused significant muscle damage, loss of strength, and soreness; however timing of ingestion of carbohydrate/protein supplement had no effect

Effect of carbohydrate-protein supplement timing on acute exercise-induced muscle damage

<p>Abstract</p> <p>Purpose</p> <p>To determine if timing of a supplement would have an effect on muscle damage, function and soreness.</p> <p>Methods</p> <p>Twenty-seven untrained men (21 ± 3 yrs) were given a supplement before or after exercise. Subjects were randomly assigned to a pre exercise (n = 9), received carbohydrate/protein drink before exercise and placebo after, a post exercise (n = 9), received placebo before exercise and carbohydrate/protein drink after, or a control group (n = 9), received placebo before and after exercise. Subjects performed 50 eccentric quadriceps contractions on an isokinetic dynamometer. Tests for creatine kinase (CK), maximal voluntary contraction (MVC) and muscle soreness were recorded before exercise and at six, 24, 48, 72, and 96 h post exercise. Repeated measures ANOVA were used to analyze data.</p> <p>Results</p> <p>There were no group by time interactions however, CK significantly increased for all groups when compared to pre exercise (101 ± 43 U/L) reaching a peak at 48 h (661 ± 1178 U/L). MVC was significantly reduced at 24 h by 31.4 ± 14.0%. Muscle soreness was also significantly increased from pre exercise peaking at 48 h.</p> <p>Conclusion</p> <p>Eccentric exercise caused significant muscle damage, loss of strength, and soreness; however timing of ingestion of carbohydrate/protein supplement had no effect.</p

Influence of Exogenous β-Hydroxybutyrate on Walking Economy and Rating of Perceived Exertion

This study investigates the effect of a supplementary ketone, β-hydroxybutyrate (BHB), on walking economy and ratings of perceived exertion in apparently healthy individuals. In a repeated-measures, crossover design, ten non-aerobically trained participants (three males; seven females) performed two stages of a duration-modified Bruce treadmill protocol. Participants blindly consumed either 1 ounce of an exogenous BHB solution (KETO) or a noncaloric placebo (CON) 30 minutes prior to exercise testing. Blood ketone and glucose concentrations were measured prior to supplementation (baseline), immediately before exercise, and after exercise. Oxygen consumption (VO2), respiratory exchange ratio (RER), energy expenditure (EE), and rating of perceived exertion (RPE) were recorded during the last two minutes of each stage. Blood BHB concentrations were significantly elevated at the pre-exercise and postexercise time points as compared to the CON condition (p \u3c .001), and blood glucose was significantly elevated postexercise in both conditions as compared to baseline levels (p \u3c .001). No significant between-trial differences (p \u3e .05) were found for VO2, RER, EE, or RPE. The intervention of this study did not produce evidence of an ergogenic benefit from BHB supplementation in a healthy subject pool

Older Black Women’s Experiences Initiating and Maintaining Physical Activity: Implications for Theory and Practice

Using a semi-structured discussion guide, 15 interviews were conducted with physically active, older, Black women living in the Eastern U.S. to examine what contributed to participants’ physical activity initiation and maintenance. Thematic analysis organized content. Constant comparison methods compared themes between participants. Participants initiated physical activity when a cue to action, such as weight gain or a medical issue, triggered a perceived need to exercise. When participants initiated physical activity, they experienced immediate unexpected benefits, such as improved energy. Participants reported continuing activity because of these initial benefits. After continued physical activity over time, participants experienced the health benefits they originally hoped to achieve. Most participants also mentioned continuing physical activity because it is “me time.” All participants reported needing to modify their physical activity routine at some point. Having a regular, yet adaptable, routine and planning skills helped participants maintain physical activity. These findings contribute to the refinement of theory, and might be useful for professionals promoting physical activity among older Black women

Physical Activity Evolution Among Older African American Women

Using a semi-structured discussion guide, 15 interviews were conducted with physically active, older, Black women living in the Eastern U.S. to examine what contributed to participants’ physical activity initiation and maintenance. Thematic analysis organized content. Constant comparison methods compared themes between participants. Participants initiated physical activity when a cue to action, such as weight gain or a medical issue, triggered a perceived need to exercise. When participants initiated physical activity, they experienced immediate unexpected benefits, such as improved energy. Participants reported continuing activity because of these initial benefits. After continued physical activity over time, participants experienced the health benefits they originally hoped to achieve. Most participants also mentioned continuing physical activity because it is “me time.” All participants reported needing to modify their physical activity routine at some point. Having a regular, yet adaptable, routine and planning skills helped participants maintain physical activity. These findings contribute to the refinement of theory, and might be useful for professionals promoting physical activity among older Black women

Timing Influence of Carbohydrate-Protein Ingestion on Muscle Soreness and Next-Day Running Performance

The present study investigates timing effects of a carbohydrate-protein (CHO-PROT) beverage on indicators of muscle damage and next day running performance. Nine trained subjects completed three trials of a 30 min downhill run, followed by a 1.5 mile treadmill running time trial 24 hours later in a blinded, crossover design. Either a CHO-PROT or non-caloric placebo beverage was given 30 min and 5 min prior to, at the 15 min mark during, immediately after, and 30 min after the downhill running protocol. In the first treatment (T1), a total of 360 kilocalories was given 30 min and 5 min prior to downhill running, as well as at the 15 min mark, with placebos used at other time points. In the second treatment (T2), an isocaloric amount was given but only immediately after and 30 min after downhill running, with placebos used at other time points. In the placebo treatment (PL), a placebo was given at all time points. There were no significant differences in the 1.5 mile time trial or soreness between trials (p \u3e 0.05). Regardless of timing, the ingestion of a CHO-PROT beverage had no effect on next day running performance or muscular soreness versus a placebo