Timing Of Post-exercise Protein Ingestion Alters Anabolic Signaling During
Prolonged Recovery
Medicine & Science in Sports & Exercise: May 2011 - Volume 43 - Issue 5 - p 136
Areta, Jose L; Burke, Louise M.

Muscle protein synthesis (MPS) is synergistically enhanced by resistance exercise and
feeding with mRNA translation initiation being a critical regulatory step. Previous
studies indicate 20 g of protein immediately after resistance exercise maximally
stimulates MPS during the early recovery period. However, no studies have examined
the effect of manipulating the quantity and timing of protein ingestion on anabolic
signaling over a whole day.

PURPOSE:To determine the time-course of anabolic signaling during prolonged
recovery from resistance exercise.

METHODS: 24 resistance trained men were randomly assigned to one of three groups.
Each reported to the laboratory following 72 h diet/activity control and an overnight
fast. Immediately following leg extension exercise (4 × 10 @ 80% 1repetition
maximum, 3 min recovery)
1) one group (PULSE) consumed an 8 × 10 g (125 mL) whey protein isolate drink at
1.5 h intervals;
2) an intermediate group (INT) consumed 4 × 20 g (250 mL) every 3 h;
3) and the final group (BOLUS) received 2 × 40 g (500 mL) 6 h apart during 12 h
passive recovery.

Muscle biopsy samples from vastus lateralis were taken at rest before exercise and 1, 4,
6, 7 and 12 h post-exercise. p70S6K Thr389 phosphorylation was measured as a
marker of translation initiation for MPS.

RESULTS:
BOLUS ingestion increased phosphorylation of p70S6K Thr389 above rest only at 1 h
(~20 fold) and 7 h post-exercise (~12 fold; both p<0.05).
INT feeding also increased Thr389 phosphorylation compared to rest at the 1 h time-
point during recovery (~12 fold, p<.05) and this effect was still evident 4 h post-
exercise (~8 fold, p<0.05) but not at any later time points.
In contrast, there were no differences in phosphorylation with PULSE. Moreover, the
phopshorylation with BOLUS and INT ingestion was greater than PULSE 1 h post-
exercise (P<0.05).

CONCLUSIONS: Pulse feeding (10 g) appears to have only modest capacity for
activating translation. In contrast, Bolus (40 g) feeding may induce transient,
repeatable activation of translational machinery while Intermediate ingestion (20 g)
extends the early, but not late, anabolic response. We show that altering the quantity
and timing of protein ingestion generates different anabolic signaling responses during
extended recovery from resistance exercise.

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1,25(OH)2Vitamin D3 Stimulates Myogenic Differentiation by Inhibiting Cell Proliferation and Modulating the Expression of Promyogenic Growth Factors and Myostatin in C2C12 Skeletal Muscle Cells
Leah A. Garcia, Keisha K. King, Monica G. Ferrini, Keith C. Norris and Jorge N. Artaza     Endocrinology August 1, 2011 vol. 152 no. 8 2976-2986

Skeletal muscle wasting is an important public health problem associated with aging, chronic disease, cancer, kidney dialysis, and HIV/AIDS. 1,25-Dihydroxyvitamin D (1,25-D3), the active form of vitamin D, is widely recognized for its regulation of calcium and phosphate homeostasis in relation to bone development and maintenance and for its calcemic effects on target organs, such as intestine, kidney, and parathyroid glands. Emerging evidence has shown that vitamin D administration improves muscle performance and reduces falls in vitamin D-deficient older adults. However, little is known of the underlying mechanism or the role 1,25-D3 plays in promoting myogenic differentiation at the cellular and/or molecular level. In this study, we examined the effect of 1,25-D3 on myoblast cell proliferation, progression, and differentiation into myotubes. C2C12 myoblasts were treated with 1,25-D3 or placebo for 1, 3, 4, 7, and 10 d. Vitamin D receptor expression was analyzed by quantitative RT-PCR, Western blottings and immunofluorescence. Expression of muscle lineage, pro- and antimyogenic, and proliferation markers was assessed by immunocytochemistry, PCR arrays, quantitative RT-PCR, and Western blottings. Addition of 1,25-D3 to C2C12 myoblasts 1) increased expression and nuclear translocation of the vitamin D receptor, 2) decreased cell proliferation, 3) decreased IGF-I expression, and 4) promoted myogenic differentiation by increasing IGF-II and follistatin expression and decreasing the expression of myostatin, the only known negative regulator of muscle mass, without changing growth differentiation factor 11 expression. This study identifies key vitamin D-related molecular pathways for muscle regulation and supports the rationale for vitamin D intervention studies in select muscle disorder conditions.

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Effects of Lactate Consumption on Blood Bicarbonate Levels and Performance During High-Intensity Exercise
IJSNEM Volume 21, Issue 4, August

The authors sought to determine the effects of oral lactate consumption on blood bicarbonate (HCO3–) levels, pH levels, and performance during high-intensity exercise on a cycle ergometer. Subjects (N = 11) were trained male and female cyclists. Time to exhaustion (TTE) and total work were measured during high-intensity exercise bouts 80 min after the consumption of 120 mg/kg body mass of lactate (L), an equal volume of placebo (PL), or no treatment (NT). Blood HCO3– increased significantly after ingestion of lactate (p

.05). No changes in pH were observed as a result of treatment. TTE and total work during the performance test increased significantly by 17% in L compared with PL and NT (p = .02). No significant differences in TTE and total work were seen between the PL and NT protocols (p = .85). The authors conclude that consuming 120 mg/kg body mass of lactate increases HCO3– levels and increases exercise performance during high-intensity cycling ergometry to exhaustion.

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Sodium and Potassium Intake and Mortality Among US Adults
Prospective Data From the Third National Health and Nutrition Examination Survey

Quanhe Yang         Arch Intern Med. 2011;171(13):1183-1191.

Background Several epidemiologic studies suggested that higher sodium and lower potassium intakes were associated with increased risk of cardiovascular diseases (CVD). Few studies have examined joint effects of dietary sodium and potassium intake on risk of mortality.

Methods To investigate estimated usual intakes of sodium and potassium as well as their ratio in relation to risk of all-cause and CVD mortality, the Third National Health and Nutrition Examination Survey Linked Mortality File (1988-2006), a prospective cohort study of a nationally representative sample of 12 267 US adults, studied all-cause, cardiovascular, and ischemic heart (IHD) diseases mortality.

Results During a mean follow-up period of 14.8 years, we documented a total of 2270 deaths, including 825 CVD deaths and 443 IHD deaths. After multivariable adjustment, higher sodium intake was associated with increased all-cause mortality (hazard ratio [HR], 1.20; 95% confidence interval [CI], 1.03-1.41 per 1000 mg/d), whereas higher potassium intake was associated with lower mortality risk (HR, 0.80; 95% CI, 0.67-0.94 per 1000 mg/d). For sodium-potassium ratio, the adjusted HRs comparing the highest quartile with the lowest quartile were HR, 1.46 (95% CI, 1.27-1.67) for all-cause mortality; HR, 1.46 (95% CI, 1.11-1.92) for CVD mortality; and HR, 2.15 (95% CI, 1.48-3.12) for IHD mortality. These findings did not differ significantly by sex, race/ethnicity, body mass index, hypertension status, education levels, or physical activity.

Conclusion Our findings suggest that a higher sodium-potassium ratio is associated with significantly increased risk of CVD and all-cause mortality, and higher sodium intake is associated with increased total mortality in the general US population.

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Sorbic acid improves growth performance and regulates insulin-like growth factor system gene expression in swine
Z.-F. Luo J ANIM SCI August 2011 vol. 89 no. 8 2356-2364

Sorbic acid (SA) is a PUFA with a conjugated double bond. The conjugated fatty acids, including CLA, are multifunctional bioactive fatty acids with the ability to improve growth performance. The effect of SA on pig growth performance was examined to determine its mechanism of action. The ADG, ADFI, and serum IGF-I concentration were examined, as were IGF-I secretion and IGF system gene expression in hepatocytes. Two hundred forty 21-d-old Duroc × Landrace × Yorkshire weaned piglets (6.86 ± 0.02 kg) were randomly divided into 4 groups, each consisting of 3 pens of 20 piglets (10 female and 10 male). The 4 groups of piglets were kept in a temperature-controlled room (26 to 28°C), and feed and water were provided to the pigs ad libitum. Weanling piglets were fed diets that included 0, 0.5, 2, or 4 g of SA/kg for 42 d. The diet supplemented with 0.5 g/kg of SA improved (P < 0.05) ADG, BW, and G:F, whereas supplementation with all 3 SA doses increased (P < 0.05) ADG and G:F at 21 to 42 d of age. The greatest concentration of plasma triglycerides was observed (P < 0.05) in the 4 g/kg of SA group. The SA increased (0.5 g of SA/kg, P > 0.05; 1 g of SA/kg, P < 0.05; and 2 g of SA/kg, P < 0.05, respectively) plasma total serum protein and globulin concentrations in a dose-dependent manner. It was noted that the smallest SA treatment dose (0.5 g/kg) dramatically increased (P < 0.05) serum IGF-I concentration but decreased (P < 0.05) the concentrations of blood urea N and cortisol. The SA increased (P < 0.05) IGF-I, IGF-II, IGF-I receptor (IGF-IR), and PPARα gene mRNA expression and IGF-I secretion, but not (P > 0.05) IGFBP or PPARγ mRNA expression, in pig primary hepatocytes. These results indicate that SA improves growth performance by regulating IGF system gene expression and hormone secretion.

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Podcast de Michael Gundill

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The effects of catechin rich teas and caffeine on energy expenditure and fat oxidation: a meta-analysis
R. Hursel             Obesity Reviews       Volume 12, Issue 7, pages e573–e581, July 2011

Different outcomes of the effect of catechin-caffeine mixtures and caffeine-only supplementation on energy expenditure and fat oxidation have been reported in short-term studies. Therefore, a meta-analysis was conducted to elucidate whether catechin-caffeine mixtures and caffeine-only supplementation indeed increase thermogenesis and fat oxidation. First, English-language studies measuring daily energy expenditure and fat oxidation by means of respiration chambers after catechin-caffeine mixtures and caffeine-only supplementation were identified through PubMed. Six articles encompassing a total of 18 different conditions fitted the inclusion criteria. Second, results were aggregated using random/mixed-effects models and expressed in terms of the mean difference in 24 h energy expenditure and fat oxidation between the treatment and placebo conditions. Finally, the influence of moderators such as BMI and dosage on the results was examined as well. The catechin-caffeine mixtures and caffeine-only supplementation increased energy expenditure significantly over 24 h (428.0 kJ (4.7%); P < 0.001 and 429.1 kJ (4.8%); P < 0.001, respectively). However, 24 h fat oxidation was only increased by catechin-caffeine mixtures (12.2 g (16.0%); P < 0.02 and 9.5 g (12.4%); P = 0.11, respectively). A dose-response effect on 24 h energy expenditure and fat oxidation occurred with a mean increase of 0.53 kJ mg−1 (P < 0.01) and 0.02 g mg−1 (P < 0.05) for catechin-caffeine mixtures and 0.44 kJ mg−1 (P < 0.001) and 0.01 g mg−1 (P < 0.05) for caffeine-only. In conclusion, catechin-caffeine mixtures or a caffeine-only supplementation stimulates daily energy expenditure dose-dependently by 0.4–0.5 kJ mg−1 administered. Compared with placebo, daily fat-oxidation was only significantly increased after catechin-caffeine mixtures ingestion.

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