The effect of milk on recovery from repeat-sprint cycling in female team-sport athletes

The consumption of milk following eccentric exercise attenuates the effects of muscle damage in team-sport athletes. However, participation in team sport involves both concentric-eccentric loading and metabolic stress. Therefore, the aim of this study was to investigate the effects of postexercise milk consumption on recovery from a cycling protocol designed to simulate the metabolic demands of team sport. Ten female team-sport athletes participated in a randomised crossover investigation. Upon completion of the protocol participants consumed 500 mL of milk (MILK) or 500 mL of an energy-matched carbohydrate (CHO) drink. Muscle function (peak torque, rate of force development, countermovement jump, 20-m sprint), muscle soreness and tiredness, serum creatine kinase, high-sensitivity C-reactive protein, and measures of oxidative stress (protein carbonyls and reduced glutathione/oxidized glutathione (GSH/GSSG) ratio) were determined at pre-exercise and 24 h, 48 h, and 72 h postexercise. MILK had a possible beneficial effect in attenuating losses in peak torque (180°/s) from baseline to 24 h (3.2% ± 7.8% vs. -6.2% ± 7.5%, MILK vs. CHO) and a possible beneficial effect in minimising soreness (baseline-48 h; baseline-72 h) and tiredness (baseline-24 h; baseline-72 h). There was no change in oxidative stress following the exercise protocol, though a likely benefit of milk was observed for GSH/GSSG ratio at baseline-24 h (0.369 ×/÷ 1.89, 1.103 ×/÷ 3.96, MILK vs. CHO). MILK had an unclear effect on all other variables. Consumption of 500 mL of milk after repeat sprint cycling had little to no benefit in minimising losses in peak torque or minimising increases in soreness and tiredness and had no effect on serum markers of muscle damage and inflammation.

Timing and pattern of postexercise protein ingestion affects whole-body protein balance in healthy children: a randomized trial

The dose and timing of postexercise protein ingestion can influence whole-body protein balance (WBPB) in adults, although comparable data from children are scarce. This study investigated how protein intake (both amount and distribution) postexercise can affect WBPB in physically active children. Thirty-five children (26 males; 9-13 years old) underwent a 5-day adaptation diet, maintaining a protein intake of 0.95 g·kg^-1·day^-1. Participants consumed [¹⁵N]glycine (2 mg·kg^-1) before performing 3 × 20 min of variable-intensity cycling, and whole-body protein kinetics were assessed over 6 and 24 h of recovery. Fifteen grams of protein was distributed across 2 isoenergetic carbohydrate-containing beverages (15 and 240 min postexercise) containing reciprocal amounts of protein (i.e., 0 + 15 g, 5 + 10 g, 10 + 5 g, and 15 + 0 g for Groups A-D, respectively). Over the 6 h that included the exercise bout and consumption of the first beverage at 15 min postexercise, WBPB (i.e., synthesis - breakdown) demonstrated a linear increase of 0.647 g·kg^-1·day^-1 per 1 g protein intake (P < 0.001). Over 24 h, robust regression revealed that WBPB was best modeled by a parabola (P < 0.05), suggesting that a maximum in WBPB was achieved between groups B and C. In conclusion, despite a dose response early in recovery, a periodized protein intake with multiple smaller doses after physical activity may be more beneficial than a single bolus dose in promoting daily WBPB in healthy active children.

Cancer cachexia and diabetes: similarities in metabolic alterations and possible treatment

Cancer cachexia is a metabolic syndrome featuring many alterations typical of type 2 diabetes (T2D). While muscle wasting is a hallmark of cachexia, epidemiological evidence also supports an accelerated age-related muscle loss in T2D. Insulin resistance manifests in both conditions and impairs glucose disposal and protein anabolism by tissues. A greater contribution of gluconeogenesis to glucose production may limit amino acid availability for muscle protein synthesis, further aggravating muscle loss. In the context of inter-dependence between glucose and protein metabolism, the present review summarizes the current state of knowledge on alterations that may lead to muscle wasting in human cancer. By highlighting the similarities with T2D, a disease that has been more extensively studied, the objective of this review is to provide a better understanding of the pathophysiology of cancer cachexia and to consider potential treatments usually targeted for T2D. Nutritional approaches aimed at stimulating protein anabolism might include specially formulated food with optimal protein and amino acid composition. Because the gradual muscle loss in T2D may be attenuated by diabetes treatment, anti-diabetic drugs might be considered in cachexia treatment. Metformin emerges as a choice candidate as it acts both on reducing gluconeogenesis and improving insulin sensitivity, and has demonstrated tumour suppressor properties in multiple cancer types. Such a multimodal approach to slow or reverse muscle wasting in cachexia warrants further investigation.

Insulin resistance of protein metabolism in type 2 diabetes and impact on dietary needs: a review

Evidence shows that the metabolism of protein is altered in type 2 diabetes mellitus and insulin resistance not only applies to glucose and lipid but protein metabolism as well. Population surveys report greater susceptibility to loss of lean tissue and muscle strength with aging in diabetes. Prevention of sarcopenia requires that protein receives more attention in dietary prescriptions. Protein intake of 1-1.2 g/kg of body weight (with weight at a body mass index of 25 kg/m(2))/day may be distributed equally among 3 meals a day, including breakfast, to optimize anabolism. Adopting a dietary pattern that provides a high plant-to-animal ratio and greater food volume favouring consumption of vegetables, legumes, fruits, complemented with fish, low fat dairy and meat (preferably cooked slowly in moisture), soy and nuts may assist with metabolic and weight control. Depending on the magnitude of energy restriction, usual protein intake should be maintained or increased, and the caloric deficit taken from fat and carbohydrate foods. Exercise before protein-rich meals improves skeletal muscle protein anabolism. Because high levels of amino acids lower glucose uptake in individuals without diabetes, the challenge remains to define the optimal protein intake and exercise regimen to protect from losses of muscle mass and strength while maintaining adequate glucose control in type 2 diabetes.