J. Luke Pryor

Effect of betaine supplementation on cycling sprint performance

PurposeTo examine the effect of betaine supplementation on cycling sprint performance.MethodsSixteen recreationally active subjects (7 females and 9 males) completed three sprint tests, each consisting of four 12 sec efforts against a resistance equal to 5.5% of body weight; efforts were separated by 2.5 min of cycling at zero resistance. Test one established baseline; test two and three were preceded by seven days of daily consumption of 591 ml of a carbohydrate-electrolyte beverage as a placebo or a carbohydrate-electrolyte beverage containing 0.42% betaine (approximately 2.5 grams of betaine a day); half the beverage was consumed in the morning and the other half in the afternoon. We used a double blind random order cross-over design; there was a 3 wk washout between trials two and three. Average and maximum peak and mean power were analyzed with one-way repeated measures ANOVA and, where indicated, a Student Newman-Keuls.ResultsCompared to baseline, betaine ingestion increased average peak power (6.4%; p < 0.001), maximum peak power (5.7%; p < 0.001), average mean power (5.4%; p = 0.004), and maximum mean power (4.4%; p = 0.004) for all subjects combined. Compared to placebo, betaine ingestion significantly increased average peak power (3.4%; p = 0.026), maximum peak power max (3.8%; p = 0.007), average mean power (3.3%; p = 0.034), and maximum mean power (3.5%; p = 0.011) for all subjects combined. There were no differences between the placebo and baseline trials.ConclusionsOne week of betaine ingestion improved cycling sprint power in recreationally active males and females.

Bike and run pacing on downhill segments predict Ironman triathlon relative success

OBJECTIVES Determine if performance and physiological based pacing characteristics over the varied terrain of a triathlon predicted relative bike, run, and/or overall success. Poor self-regulation of intensity during long distance (Full Iron) triathlon can manifest in adverse discontinuities in performance. DESIGN Observational study of a random sample of Ironman World Championship athletes. High performing and low performing groups were established upon race completion. METHODS Participants wore global positioning system and heart rate enabled watches during the race. Percentage difference from pre-race disclosed goal pace (%off) and mean HR were calculated for nine segments of the bike and 11 segments of the run. Normalized graded running pace (accounting for changes in elevation) was computed via analysis software. Step-wise regression analyses identified segments predictive of relative success and HP and LP were compared at these segments to confirm importance. RESULTS %Off of goal velocity during two downhill segments of the bike (HP: -6.8±3.2%, -14.2±2.6% versus LP: -1.2±4.2%, -5.1±11.5%; p<0.020) and %off from NGP during one downhill segment of the run (HP: 4.8±5.2% versus LP: 33.3±38.7%; p=0.033) significantly predicted relative performance. Also, HP displayed more consistency in mean HR (141±12 to 138±11 bpm) compared to LP (139±17 to 131±16 bpm; p=0.019) over the climb and descent from the turn-around point during the bike component. CONCLUSIONS Athletes who maintained faster relative speeds on downhill segments, and who had smaller changes in HR between consecutive up and downhill segments were more successful relative to their goal times.

Repetitive Box Lifting Performance is Impaired in a Hot Environment: Implications for Altered Work-Rest Cycles

This study investigated the effects of environmental temperature on repetitive box lifting (RBL) performance, associated stress hormone and creatine kinase (CK) responses. Ten healthy males performed two experimental trials in a random crossover design. The trials consisted of three 40 min (10 min sitting, 20 min standing, and 10 min RBL) circuits performed in either 23°C or 38°C followed by a 180 min seated recovery period in 23°C. RBL performance (i.e., number of boxes lifted) was reduced (p ≤ 0.05) in 38°C compared to the 23°C trial. Physiological Strain Index was significantly different between trials (38°C: 8.5 ± 1.1 versus 23°C: 7.2 ± 0.7; p ≤ 0.01). Plasma testosterone was elevated (p ≤ 0.05) across both trials and then decreased at 60 min recovery, compared to pre-exercise (PRE) measures, but was higher (p ≤ 0.05) during the 38°C trial. Plasma cortisol increased (p ≤ 0.05) at 60 min during both trials and remained elevated until 120 min in 23°C, and until 60 min recovery in 38°C. Serum CK was greater through 48 hr post compared to PRE values in both trials. Thus, 10 min RBL performance was reduced in 38°C despite the 30-min rest periods between RBL intervals. Plasma testosterone and cortisol were generally higher during the 38°C trial, suggesting a greater stress response. Additional research is needed to determine optimal work:rest cycles for maximizing work performance in thermally oppressive environments.

The Addition of Beta-hydroxy-beta-methylbutyrate and Isomaltulose to Whey Protein Improves Recovery from Highly Demanding Resistance Exercise

Objective: This study evaluated whether a combination of whey protein (WP), calcium beta-hydroxy-beta-methylbutyrate (HMB), and carbohydrate exert additive effects on recovery from highly demanding resistance exercise. Methods: Thirteen resistance-trained men (age: 22.6 ± 3.9 years; height: 175.3 ± 12.2 cm; weight: 86.2 ± 9.8 kg) completed a double-blinded, counterbalanced, within-group study. Subjects ingested EAS Recovery Protein (RP; EAS Sports Nutrition/Abbott Laboratories, Columbus, OH) or WP twice daily for 2 weeks prior to, during, and for 2 days following 3 consecutive days of intense resistance exercise. The workout sequence included heavy resistance exercise (day 1) and metabolic resistance exercise (days 2 and 3). The subjects performed no physical activity during day 4 (+24 hours) and day 5 (+48 hours), where recovery testing was performed. Before, during, and following the 3 workouts, treatment outcomes were evaluated using blood-based muscle damage markers and hormones, perceptual measures of muscle soreness, and countermovement jump performance. Results: Creatine kinase was lower for the RP treatment on day 2 (RP: 166.9 ± 56.4 vs WP: 307.1 ± 125.2 IU · L−1, p ≤ 0.05), day 4 (RP: 232.5 ± 67.4 vs WP: 432.6 ± 223.3 IU · L−1, p ≤ 0.05), and day 5 (RP: 176.1 ± 38.7 vs 264.5 ± 120.9 IU · L−1, p ≤ 0.05). Interleukin-6 was lower for the RP treatment on day 4 (RP: 1.2 ± 0.2 vs WP: 1.6 ± 0.6 pg · ml−1, p ≤ 0.05) and day 5 (RP: 1.1 ± 0.2 vs WP: 1.6 ± 0.4 pg · ml−1, p ≤ 0.05). Muscle soreness was lower for RP treatment on day 4 (RP: 2.0 ± 0.7 vs WP: 2.8 ± 1.1 cm, p ≤ 0.05). Vertical jump power was higher for the RP treatment on day 4 (RP: 5983.2 ± 624 vs WP 5303.9 ± 641.7 W, p ≤ 0.05) and day 5 (RP: 5792.5 ± 595.4 vs WP: 5200.4 ± 501 W, p ≤ 0.05). Conclusions: Our findings suggest that during times of intense conditioning, the recovery benefits of WP are enhanced with the addition of HMB and a slow-release carbohydrate. We observed reductions in markers of muscle damage and improved athletic performance.

Coach-led preventive training program in youth soccer players improves movement technique

Long-term implementation of preventive training programs (PTP) in youth sport requires coach involvement. However, the optimal training of coaches to effectively implement a PTP remains unknown. It is also unknown if the benefits of PTP can be enhanced with multiple sport seasons of exposure. OBJECTIVES To evaluate the influence of prior PTP exposure on movement technique in youth soccer players after completing a coach-led PTP. DESIGN Cluster-randomized controlled trial. METHODS Twelve youth soccer teams (n=89; age range 8-14 years) were divided into groups with (Experience (EXP); 6 teams [n=18 females, n=25 males]) and without (Novice (NOV); 6 teams [n=30 females, n=16 males]) previous professional-led PTP experience. The coaches and players of the EXP teams were exposed to an eight-week professional-led PTP before the coach-led PTP. EXP and NOV coaches attended the educational workshop prior to implementing the coach-led PTP. The Landing Error Scoring System (LESS) was used to evaluate movement technique. RESULTS Both groups improved LESS scores over time (mean difference±SD [post-pre]=-0.8±0.2, 95%CI [-1.2, -0.4], p=0.0001). Of the 64 participants classified as high risk for injury (LESS ≥5) prior to PTP implementation, a greater proportion of EXP (n=14) compared to NOV (n=7) participants changed risk classification from high to low (LESSΔ≥1 and LESS <5; p=0.03). CONCLUSIONS Our PTP enhanced movement technique regardless of PTP experience, but the benefits of the PTP impacted a proportionally greater number of players with previous PTP experience supporting continued PTP implementation. Coaches effectively implemented an exercise-based PTP after attending a training workshop regardless of previous PTP experience.

Hydration Status and Sodium Balance of Endurance Runners Consuming Postexercise Supplements of Varying Nutrient Content.

Postexercise protein and sodium supplementation may aid recovery and rehydration. Preserved beef provides protein and contains high quantities of sodium that may alter performance related variables in runners. The purpose of this study was to determine the effects of consuming a commercial beef product postexercise on sodium and water balance. A secondary objective was to characterize effects of the supplementation protocols on hydration, blood pressure, body mass, and running economy. Eight trained males (age = 22 ± 3 y, VO2max = 66.4 ± 4.2 ml·kg-1·min-1) completed three identical weeks of run training (6 run·wk-1, 45 ± 6 min·run-1, 74 ± 5% HRR). After exercise, subjects consumed either, a beef nutritional supplement (beef jerky; [B]), a standard recovery drink (SRD), or SRD+B in a randomized counterbalanced design. Hydration status was assessed via urinary biomarkers and body mass. No main effects of treatment were observed for 24 hr urine volume (SRD, 1.7 ± 0.5; B, 1.8 ± 0.6; SRD+B, 1.4 ± 0.4 L·d-1), urine specific gravity (1.016 ± 0.005, 1.018 ± 0.006, 1.017 ± 0.006) or body mass (68.4 ± 8.2, 68.3 ± 7.7, 68.2 ± 8.1 kg). No main effect of treatment existed for sodium intake-loss (-713 ± 1486; -973 ± 1123; -980 ± 1220 mg·d-1). Mean arterial pressure (81.0 ± 4.6, 81.1 ± 7.3, 83.8 ± 5.4 mm Hg) and average exercise running economy (VO2: SRD, 47.9 ± 3.2; B, 47.2 ± 2.6; SRD+B, 46.2 ± 3.4 ml·kg-1·min-1) was not affected. Urinary sodium excretion accounted for the daily sodium intake due to the beef nutritional supplement. Findings suggest the commercial beef snack is a viable recovery supplement following endurance exercise without concern for hydration status, performance decrements, or cardiovascular consequences.