Breakfast before resistance exercise lessens urinary markers of muscle protein breakdown in young men: A crossover trial.

OBJECTIVES: Skipping breakfast prolongs the fasting state initiated after the last meal consumed the previous day and can have negative effects on muscle protein balance. The aim of this crossover trial was to examine the effects of skipping breakfast before a single bout of resistance exercise (RE) on muscle protein breakdown (MPB), as assessed using the urinary 3-methylhistidine/creatinine ratio (3-MH/Cr). METHODS: Thirteen healthy young men, who habitually consumed breakfast (21.8 ± 1.1 y of age), were assigned to eating breakfast (EB) and skipping breakfast (SB) conditions. Participants consumed meat-free diets throughout the 5-d experiment. On day 5, individuals in the EB group consumed breakfast (497 kcal) 2.5 h before RE (75% repetition maximum), whereas those in the SB group consumed the same meal after dinner. RESULTS: In the two-way analysis of variance, significant interactions were observed with blood insulin and free fatty acid levels, and the 3-MH/Cr ratio (P < 0.05). We confirmed a significantly greater decrease in the insulin level pre-RE (P < 0.001; d = 3.281), and increases in the free fatty acid level pre-RE (P < 0.001; d = 1.437) and post-RE (P = 0.013; d = 0.811) and the 3-MH/Cr ratio 6 (P < 0.001; d = 0.878) and 8 h (P < 0.001; d = 0.634) post-RE in the SB condition than in the EB condition. CONCLUSION: Eating breakfast before RE can be beneficial for MPB suppression. The importance of breakfast consumption in terms of positive muscle protein balance is emphasized on sports fields.

Validity and Reproducibility of a Self-Administered Food Frequency Questionnaire for the Assessment of Sugar Intake in Middle-Aged Japanese Adults.

We evaluated the validity and reproducibility of estimated sugar intakes using a food frequency questionnaire (FFQ) among middle-aged Japanese adults in the Japan Public Health Centre-Based Prospective (JPHC) study. In subsamples of the JPHC study (Cohorts I and II in multiple areas), we computed Spearman's correlations of FFQ results with urine sugar concentrations and dietary records (DR) for validity; we evaluated correlations between two FFQs for reproducibility. During 1994⁻1998, participants (Cohort I: n = 27 [men], n = 45 [women]) provided two (spring and fall) 24-h urine samples and completed 7-consecutive-day DR per season (I: n = 99, n = 113; II: n = 168, n = 171) and two FFQs (147 food items) at yearly intervals (I: n = 101, n = 108; II: n = 143, n = 146). Sugar intakes from FFQ were correlated with urinary sugar (de-attenuated correlations: 0.40; 95%CI: 0.19, 0.58). After adjustment for sociodemographic and lifestyle variables, correlations between FFQ and DR for men and women were 0.57 (0.42, 0.69) and 0.41 (0.24, 0.55) (I) and 0.56 (0.44, 0.65) and 0.34 (0.20, 0.47) (II), respectively. Correlations between FFQs for men and women were 0.63 (0.49, 0.73) and 0.55 (0.41, 0.67) (I) and 0.66 (0.55, 0.74) and 0.63 (0.52, 0.72) (II). In conclusion, our study showed moderate FFQ validity and reproducibility for sugar intake evaluation.