High-dose short-term creatine supplementation without beneficial effects in professional cyclists: a randomized controlled trial.

BACKGROUND: Growing evidence supports the ergogenic effects of creatine supplementation on muscle power/strength, but its effects on endurance performance remain unclear. We assessed the effects of high-dose short-term creatine supplementation in professional cyclists during a training camp. METHODS: The study followed a double-blind, randomized parallel design. Twenty-three professional U23 cyclists (19 ± 1 years, maximum oxygen uptake: 73.0 ± 4.6 mL/kg/min) participated in a 6-day training camp. Participants were randomized to consume daily either a recovery drink (containing carbohydrates and protein) with a 20-g creatine supplement (creatine group, n = 11) or just the recovery drink (placebo group, n = 12). Training loads and dietary intake were monitored, and indicators of fatigue/recovery (Hooper index, countermovement jump height), body composition, and performance (10-second sprint, 3-, 6-, and 12-minute time trials, respectively, as well as critical power and W') were assessed as study outcomes. RESULTS: The training camp resulted in a significant (p < 0.001) increase of training loads (+50% for total training time and + 61% for training stress score, compared with the preceding month) that in turn induced an increase in fatigue indicators (significant time effect [p < 0.001] for delayed-onset muscle soreness, fatigue, and total Hooper index) and a decrease in performance (significant time effect [p = 0.020] for critical power, which decreased by -3.8%). However, no significant group-by-time interaction effect was found for any of the study outcomes (all p > 0.05). CONCLUSIONS: High-dose short-term creatine supplementation seems to exert no consistent beneficial effects on recovery, body composition or performance indicators during a strenuous training period in professional cyclists.

Pre-sleep protein supplementation in professional cyclists during a training camp: a three-arm randomized controlled trial.

Background: The effects of pre-sleep protein supplementation on endurance athletes remain unclear, particularly whether its potential benefits are due to the timing of protein intake or solely to an increased total protein intake. We assessed the effects of pre-sleep protein supplementation in professional cyclists during a training camp accounting for the influence of protein timing. Methods: Twenty-four professional U23 cyclists (19 ± 1 years, peak oxygen uptake: 79.8 ± 4.9 ml/kg/min) participated in a six-day training camp. Participants were randomized to consume a protein supplement (40 g of casein) before sleep (n = 8) or in the afternoon (n = 8), or an isoenergetic placebo (40 g of carbohydrates) before sleep (n = 8). Indicators of fatigue/recovery (Hooper index, Recovery-Stress Questionnaire for Athletes, countermovement jump), body composition, and performance (1-, 5-, and 20-minute time trials, as well as the estimated critical power) were assessed as study outcomes. Results: The training camp resulted in a significant (p < 0.001) increase in training loads (e.g. training stress score of 659 ± 122 per week during the preceding month versus 1207 ± 122 during the training camp), which induced an increase in fatigue indicators (e.g. time effect for Hooper index p < 0.001) and a decrease in performance (e.g. time effect for critical power p = 0.002). Protein intake was very high in all the participants (>2.5 g/kg on average), with significantly higher levels found in the two protein supplement groups compared to the placebo group (p < 0.001). No significant between-group differences were found for any of the analyzed outcomes (all p > 0.05). Conclusions: Protein supplementation, whether administered before sleep or earlier in the day, exerts no beneficial effects during a short-term strenuous training period in professional cyclists, who naturally consume a high-protein diet.

Cardiorespiratory fitness and adiposity in breast cancer survivors: is meeting current physical activity recommendations really enough?

PURPOSE: Breast cancer (BC) survivors are becoming increasingly predisposed to cardiovascular disease (CVD) mortality. Low cardiorespiratory fitness and physical activity (PA) levels, as well as high values of adiposity indices, contribute to CVD risk. We evaluated adiposity, cardiorespiratory profile, and PA levels in two independent cohorts of BC survivors. METHODS: Data were collected from two groups (99% women) from different areas of Madrid (Spain): group 1, n = 110, age 51.4 ± 9.7 years, median time from diagnosis 365 days (95% confidence interval [CI], 354-401), and group 2, n = 93, age 54.7 ± 8.9 years, 1714 days (95% CI, 1502-1938). We estimated peak oxygen uptake (VO2peak) and measured body mass index (BMI), waist circumference (WC), waist-to-hip index, and accelerometry-determined PA. RESULTS: Both groups had values of BMI in the overweight range (25.3 ± 4.3 and 27.1 ± 5.1 kg/m2, p = 0.003). Estimated VO2peak levels were lower in group 2 than in group 1 (28.1 ± 9.1 and 23.7 ± 8.8 ml/kg/min, p < 0.001), although levels in both groups were low. Yet, the majority of participants in both groups (81 and 88%, p = 0.234) met international PA recommendations (235 ± 196 and 351 ± 173 min/week of moderate-vigorous PA, p < 0.001). Both groups had very low levels of vigorous PA. These results were essentially independent of type of treatment (anthracycline/radiotherapy). CONCLUSIONS: We found a poor cardiorespiratory profile in two independent BC cohorts that differed in median time from diagnosis (as well in socioeconomic status), supporting the notion that implementation of PA (possibly focusing on vigorous PA) and dietary intervention is urgently needed in this patient population.