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Chocolate milk for recovery from exercise: a systematic review and meta-analysis of controlled clinical trials.
Amiri, M, Ghiasvand, R, Kaviani, M, Forbes, SC, Salehi-Abargouei, A
European journal of clinical nutrition. 2019;73(6):835-849
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Plain language summary
Post-exercise nutrition is highly important for recovery and performance. It has been proposed that beverages containing protein, carbohydrates and electrolytes may attenuate exercise-induced fatigue and dehydration. Chocolate milk contains all of these nutrients and has recently drawn attention as a plausible post-exercise recovery drink. Therefore the aim of this study was to assess the efficacy of chocolate milk on post-exercise recovery markers. This review included 12 studies and a sub-analysis found significant improvements in time to exhaustion and lowered post-exercise blood-lactate. There were no significant differences between the other markers considered in the analysis. Based on these results, the authors deem chocolate milk to provide equivalent outcomes to placebo or other recovery drinks. As the available research is limited, the authors recommended high quality controlled trials with larger sample sizes be done to gain more clarity on best-practice for post-exercise recovery.
Abstract
BACKGROUND/OBJECTIVES Chocolate milk (CM) contains carbohydrates, proteins, and fat, as well as water and electrolytes, which may be ideal for post-exercise recovery. We systematically reviewed the evidence regarding the efficacy of CM compared to either water or other "sport drinks" on post-exercise recovery markers. SUBJECTS/METHODS PubMed, Scopus, and Google scholar were explored up to April 2017 for controlled trials investigating the effect of CM on markers of recovery in trained athletes. RESULTS Twelve studies were included in the systematic review (2, 9, and 1 with high, fair and low quality, respectively) and 11 had extractable data on at least one performance/recovery marker [7 on ratings of perceived exertion (RPE), 6 on time to exhaustion (TTE) and heart rate (HR), 4 on serum lactate, and serum creatine kinase (CK)]. The meta-analyses revealed that CM consumption had no effect on TTE, RPE, HR, serum lactate, and CK (P > 0.05) compared to placebo or other sport drinks. Subgroup analysis revealed that TTE significantly increases after consumption of CM compared to placebo [mean difference (MD) = 0.78 min, 95% confidence interval (CI): 0.27, 1.29, P = 0.003] and carbohydrate, protein, and fat-containing beverages (MD = 6.13 min, 95% CI: 0.11, 12.15, P = 0.046). Furthermore, a significant attenuation on serum lactate was observed when CM was compared with placebo (MD = -1.2 mmol/L, 95% CI: -2.06,-0.34, P = 0.006). CONCLUSION CM provides either similar or superior results when compared to placebo or other recovery drinks. Overall, the evidence is limited and high-quality clinical trials with more well-controlled methodology and larger sample sizes are warranted.
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The effects of a ketogenic diet on exercise metabolism and physical performance in off-road cyclists.
Zajac, A, Poprzecki, S, Maszczyk, A, Czuba, M, Michalczyk, M, Zydek, G
Nutrients. 2014;6(7):2493-508
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Free full text
Plain language summary
While it is well-known that nutrient availability affects numerous aspects of exercise metabolism, new concepts of improving endurance performance are being explored. Sports nutrition has historically focused on a high carbohydrate diet to increase glycogen stores, however there is increasing evidence that a low carbohydrate, high fat diet may benefit endurance athletes. The aim of this crossover study was to determine the effects of a long-term keteogenic diet on aerobic performance and exercise metabolism in eight male cyclists. The participants were assigned to either a mixed or ketogenic diet for one month with a one-week recovery period and performed an exercise protocol consisting of moderate and high intensities. The findings indicated that consuming a low carbohydrate diet promotes fat oxidation during moderate-intensity and reduces post-exercise muscle damage. Based on these results, the authors conclude that long-term, high fat diets may be favourable for aerobic endurance athletes during the preparatory season.
Abstract
The main objective of this research was to determine the effects of a long-term ketogenic diet, rich in polyunsaturated fatty acids, on aerobic performance and exercise metabolism in off-road cyclists. Additionally, the effects of this diet on body mass and body composition were evaluated, as well as those that occurred in the lipid and lipoprotein profiles due to the dietary intervention. The research material included eight male subjects, aged 28.3 ± 3.9 years, with at least five years of training experience that competed in off-road cycling. Each cyclist performed a continuous exercise protocol on a cycloergometer with varied intensity, after a mixed and ketogenic diet in a crossover design. The ketogenic diet stimulated favorable changes in body mass and body composition, as well as in the lipid and lipoprotein profiles. Important findings of the present study include a significant increase in the relative values of maximal oxygen uptake (VO2max) and oxygen uptake at lactate threshold (VO2 LT) after the ketogenic diet, which can be explained by reductions in body mass and fat mass and/or the greater oxygen uptake necessary to obtain the same energy yield as on a mixed diet, due to increased fat oxidation or by enhanced sympathetic activation. The max work load and the work load at lactate threshold were significantly higher after the mixed diet. The values of the respiratory exchange ratio (RER) were significantly lower at rest and during particular stages of the exercise protocol following the ketogenic diet. The heart rate (HR) and oxygen uptake were significantly higher at rest and during the first three stages of exercise after the ketogenic diet, while the reverse was true during the last stage of the exercise protocol conducted with maximal intensity. Creatine kinase (CK) and lactate dehydrogenase (LDH) activity were significantly lower at rest and during particular stages of the 105-min exercise protocol following the low carbohydrate ketogenic diet. The alterations in insulin and cortisol concentrations due to the dietary intervention confirm the concept that the glucostatic mechanism controls the hormonal and metabolic responses to exercise.
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A low glycemic index meal before exercise improves endurance running capacity in men.
Wu, CL, Williams, C
International journal of sport nutrition and exercise metabolism. 2006;16(5):510-27
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Plain language summary
Carbohydrate loading before exercise is thought to improve exercise performance. However high carbohydrate meals suppress fat metabolism which is important for energy production during prolonged exercise. A low glycemic index (GI) meal consumed 3 to 4 h before exercise is therefore often adopted by sports people. This randomised cross over trial with a wash out period investigated the effects of ingesting a low GI meal or high GI meal 3 hours prior to exercise on endurance running capacity in 8 male recreational runners. The average running time during the low GI trial was significantly longer than high GI trial. Fat oxidation rates were higher during exercise after the low GI meal than after the high GI meal. The authors speculate that subjects began exercise with a higher muscle glycogen concentration after the high GI trial than in the low GI trial and consequently may have used more glycogen during prolonged exercise. In the low GI trial the lower rate of glycogenolysis and higher rate of fat oxidation may have allowed a more rapid “up-regulation” of fat metabolism that was sufficient to support energy expenditure for longer than during the high GI trial. In summary, ingestion of a low GI meal 3 h before exercise resulted in a greater endurance capacity than after the ingestion of a high GI meal.
Abstract
This study investigated the effects of ingesting a low (LGI) or high (HGI) glycemic index carbohydrate (CHO) meal 3 h prior to exercise on endurance running capacity. Eight male recreational runners undertook two trials (LGI or HGI) which were randomized and separated by 7 d. After an overnight fast (12 h) the subjects ingested either a LGI or HGI meal 3 h prior to running at 70% VO2max until exhaustion. The meals contained 2 g/kg body mass CHO and were isocaloric and iso-macronutrient with calculated GI values 77 and 37 for the HGI and LGI respectively. The run times for the LGI and HGI trials were 108.8 +/- 4.1 min and 101.4 +/- 5.2 min respectively (P = 0.038). Fat oxidation rates were higher during exercise after the LGI meal than after the HGI meal (P < 0.05). In summary, ingestion of a LGI meal 3 h before exercise resulted in a greater endurance capacity than after the ingestion of a HGI meal.