International journal of sport nutrition and exercise metabolism最新文献

An increase in visceral fat is associated with an increase in insulin resistance, so reducing body fat mass through exercise may help alleviate type 2 diabetes mellitus (T2DM). The current meta-analysis evaluated the effect of changes in body fat via an intervention of regular exercise on hemoglobin A1c (HbA1c) in patients with T2DM. The inclusion criteria were randomized controlled trials involving adults with T2DM, intervention involving exercise alone, an overall duration of intervention ≥12 weeks, and reporting HbA1c and body fat mass. The mean differences (MDs) were defined as the MD between the exercise group and the control group, and the MDs in HbA1c (in percentage) and body fat mass (in kilograms) were calculated. All MDs in HbA1c were pooled as overall effects. A meta-regression analysis was performed to evaluate the relationship between the MD in the body fat mass (in kilograms) and the MD in HbA1c. Twenty studies (1,134 subjects) were analyzed. The pooled MD in HbA1c (in percentage) decreased significantly (-0.4; 95% confidence interval [-0.5, -0.3]) but contained significant heterogeneity (Q = 52.7, p < .01; I2 = 41.6%). A meta-regression analysis showed that a decrease in the MD in body fat mass was significantly associated with a decrease in the MD in HbA1c (R2 = 80.0%) and heterogeneity decreased (Q = 27.3, p = .61; I2 = 11.9%), and a reduction in body fat mass of 1 kg was estimated to decrease the HbA1c (%) by approximately 0.2. The current study suggested that a decrease in HbA1c due to regular exercise depends on a reduction in body fat mass in patients with T2DM.

Branched-chain amino acids (BCAA) and carbohydrate (CHO) are commonly recommended postexercise supplements. However, no study has examined the interaction of CHO and BCAA ingestion on myofibrillar protein synthesis (MyoPS) rates following exercise. We aimed to determine the response of MyoPS to the co-ingestion of BCAA and CHO following an acute bout of resistance exercise. Ten resistance-trained young men completed two trials in counterbalanced order, ingesting isocaloric drinks containing either 30.6-g CHO plus 5.6-g BCAA (B + C) or 34.7-g CHO alone following a bout of unilateral, leg resistance exercise. MyoPS was measured postexercise with a primed, constant infusion of L-[ring13C6] phenylalanine and collection of muscle biopsies pre- and 4 hr postdrink ingestion. Blood samples were collected at time points before and after drink ingestion. Serum insulin concentrations increased to a similar extent in both trials (p > .05), peaking at 30 min postdrink ingestion. Plasma leucine (514 ± 34 nmol/L), isoleucine (282 ± 23 nmol/L), and valine (687 ± 33 nmol/L) concentrations peaked at 0.5 hr postdrink in B + C and remained elevated for 3 hr during exercise recovery. MyoPS was ∼15% greater (95% confidence interval [-0.002, 0.028], p = .039, Cohen's d = 0.63) in B + C (0.128%/hr ± 0.011%/hr) than CHO alone (0.115%/hr ± 0.011%/hr) over the 4 hr postexercise period. Co-ingestion of BCAA and CHO augments the acute response of MyoPS to resistance exercise in trained young males.

First morning urine (FMU) assessment would be a practical and convenient solution for clinically acceptable detection of underhydration prior to competition/training, and for the general public. Thus, we thus sought to determine the diagnostic accuracy of FMU as a valid indicator of recent (previous 24 hr, 5 days average) hydration practices. For 5 consecutive days and one final morning, 67 healthy women (n = 38) and men (n = 29; age: 20 [1] years, body mass index: 25.9 [5.5]) completed 24-hr diet logs for total water intake (from beverages and foods, absolute and relative to body mass), 24-hr urine and FMU collection (last morning only) for osmolality (Osm), specific gravity (SG), and color (Col), and morning blood sampling for plasma osmolality and copeptin. Correlations determined significance and relationship strength among FMU and all other variables. Area under the receiver operating characteristic curves, sensitivity, specificity, and positive likelihood ratios were employed using previously reported values to indicate underhydration (total water intake < 30 ml/kg, osmolality > 500, and >800 mOsm/kg, specific gravity > 1.017, and copeptin > 6.93 pmol/L). FMU_Osm and FMU_SG were significantly correlated (p < .05) to all variables except the previous 5-day plasma osmolality. FMU_Col was only significantly correlated with other color time intervals and total water intake per gram. FMU_Osm held greatest utility (area under the receiver operating characteristic curve, sensitivity, and specificity >80%) overall, with the best outcome being FMU_Osm indicating a previous 24-hr osmolality threshold of 500 mOsm/kg (FMU_Osm criterion >710 mOsm/kg and positive likelihood ratio = 5.9). With less effort and cost restriction, FMU is a viable metric to assess underhydration.

The aim of this audit was to assess the representation of female athletes, dietary control methods, and gold standard female methodology that underpins the current guidelines for chronic carbohydrate (CHO) intake strategies for athlete daily training diets. Using a standardized audit, 281 studies were identified that examined high versus moderate CHO, periodized CHO availability, and/or low CHO, high fat diets. There were 3,735 total participants across these studies with only ∼16% of participants being women. Few studies utilized a design that specifically considered females, with only 16 studies (∼6%) including a female-only cohort and six studies (∼2%) with a sex-based comparison in their statistical procedure, in comparison to the 217 studies (∼77%) including a male-only cohort. Most studies (∼72%) did not provide sufficient information to define the menstrual status of participants, and of the 18 studies that did, optimal methodology for control of ovarian hormones was only noted in one study. While ∼40% of male-only studies provided all food and beverages to participants, only ∼20% of studies with a female-specific design used this approach for dietary control. Most studies did not implement strategies to ensure compliance to dietary interventions and/or control energy intake during dietary interventions. The literature that has contributed to the current guidelines for daily CHO intake is lacking in research that is specific to, or adequately addresses, the female athlete. Redressing this imbalance is of high priority to ensure that the female athlete receives evidence-based recommendations that consider her specific needs.

Objective: To determine whether statin medication in individuals with obesity, dyslipidemia, and metabolic syndrome affects their capacity to mobilize and oxidize fat during exercise.

Methods: Twelve individuals with metabolic syndrome pedaled during 75 min at 54 ± 13% V˙O2max (5.7 ± 0.5 metabolic equivalents) while taking statins (STATs) or after 96-hr statin withdrawal (PLAC) in a randomized double-blind fashion.

Results: At rest, PLAC increased low-density lipoprotein cholesterol (i.e., STAT 2.55 ± 0.96 vs. PLAC 3.16 ± 0.76 mmol/L; p = .004) and total cholesterol blood levels (i.e., STAT 4.39 ± 1.16 vs. PLAC 4.98 ± 0.97 mmol/L; p = .008). At rest, fat oxidation (0.99 ± 0.34 vs. 0.76 ± 0.37 μmol·kg-1·min-1 for STAT vs. PLAC; p = .068) and the rates of plasma appearance of glucose and glycerol (i.e., Ra glucose-glycerol) were not affected by PLAC. After 70 min of exercise, fat oxidation was similar between trials (2.94 ± 1.56 vs. 3.06 ± 1.94 μmol·kg-1·min-1, STA vs. PLAC; p = .875). PLAC did not alter the rates of disappearance of glucose in plasma during exercise (i.e., 23.9 ± 6.9 vs. 24.5 ± 8.2 μmol·kg-1·min-1 for STAT vs. PLAC; p = .611) or the rate of plasma appearance of glycerol (i.e., 8.5 ± 1.9 vs. 7.9 ± 1.8 μmol·kg-1·min-1 for STAT vs. PLAC; p = .262).

Conclusions: In patients with obesity, dyslipidemia, and metabolic syndrome, statins do not compromise their ability to mobilize and oxidize fat at rest or during prolonged, moderately intense exercise (i.e., equivalent to brisk walking). In these patients, the combination of statins and exercise could help to better manage their dyslipidemia.

β-Alanine (BA) is one of the most widely used sport supplements, due to its capacity to improve high-intensity exercise performance by increasing muscle carnosine (MCarn) content, and consequently, the buffering capacity of the muscle. BA is also available in a variety of animal foods, but little is currently known about the influence of dietary BA intake on MCarn. The aim of the current study was to compile a detailed summary of available data on the BA content of commonly consumed foods, and to explore whether associations could be detected between self-reported dietary BA intake and skeletal MCarn in a group of 60 healthy, active, omnivorous men and women. Dietary BA intake was assessed via 3-day food records, and MCarn content assessed by high-performance liquid chromatography. A series of univariate and multivariate linear regression models were used to explore associations between estimated dietary BA and MCarn. No evidence of associations between dietary BA intake and MCarn were identified, with effect sizes close to zero calculated from models accounting for key demographic variables (f2 ≤ 0.02 for all analyses). These findings suggest that capacity to increase MCarn via dietary strategies may be limited, and that supplementation may be required to induce increases of the magnitude required to improve performance.

This study investigated within-subject variability in the circulating metabolome under controlled conditions, and whether divergent exercise training backgrounds were associated with alterations in the circulating metabolome assessed in resting samples. Thirty-seven men comprising of endurance athletes (END; body mass, 71.0 ± 6.8 kg; fat-free mass index, 16.9 ± 1.1 kg/m2), strength athletes (STR; 94.5 ± 8.8 kg; 23.0 ± 1.8 kg/m2), and recreationally active controls (CON; 77.6 ± 7.7 kg; 18.1 ± 1.0 kg/m2) provided blood samples after an overnight fast on two separate occasions controlled for time of day of sampling, recent dietary intake, time since last meal, and time since last exercise training session. A targeted profile of metabolites, performed using liquid chromatography and mass spectrometry on plasma samples, identified 166 individual metabolites and metabolite features, which were analyzed with intraclass correlation coefficients, a multilevel principal component analysis, and univariate t tests adjusted for multiple comparisons. The median intraclass correlation coefficient was .49, with 46 metabolites displaying good reliability and 31 metabolites displaying excellent reliability. No difference in the abundance of any individual metabolite was identified within groups when compared between visits, but a combined total of 44 metabolites were significantly different (false discovery rate <0.05) between groups (END vs. CON, 42 metabolites; STR vs. CON, 10 metabolites; and END vs. STR, five metabolites). Under similar measurement conditions, the reliability of resting plasma metabolite concentrations varies largely at the level of individual metabolites with ∼48% of metabolites displaying good-to-excellent reliability. However, a history of exercise training was associated with alterations in the abundance of ∼28% of metabolites in the targeted profile employed in this study.