Caffeine has shown to improve exercise performance. Therefore, caffeine is a popular supplement among athletes.
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There appears to be much variation in the individual response to caffeine. This may be explained by variation in the CYP1A2 gene, which determines whether caffeine is metabolized fast or slow. Therefore, the effects of caffeine may depend on the activity of this gene.
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This study investigated whether the impact of caffeine on endurance performance differed between slow and fast caffeine metabolizers. The subjects were male athletes and ingested different doses of caffeine (0, 2, or 4 mg/kg) ~30 min before a 10-km cycling time trial.
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The fast metabolizers improved performance by 5% with the 2 mg/kg dose and 7% with the 4 mg/kg dose of caffeine.
However, the slow metabolizers had 5% worse performance with the 2 mg/kg dose and a 14% worse performance with the 4 mg/kg dose.
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Subjects who were neither fast nor slow caffeine metabolizers (‘in between’) did not show a difference in performance with caffeine.
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It should be noted that only 8% of the participants were categorized as slow metabolizers. 49% were categorized as fast metabolizers, while 43% of the participants were ‘in between’.
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In conclusion, the effect of caffeine differs between people. In most people, it improves or has no effect on exercise performance. In contrast, it decreases performance in some people.
The ketogenic diet restricts carbohydrates with the purpose of lowering insulin levels. Insulin is a hormone that is involved in fat metabolism. Therefore, some suggest that a ketogenic diet is very effective for fat loss.
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This study investigated whether a ketogenic diet increases fat loss compared to a high-carbohydrate diet in overweight and obese men.
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Our new paper:
Pre-sleep Protein Ingestion Increases Mitochondrial Protein Synthesis Rates During Overnight Recovery from Endurance Exercise: A Randomized Controlled Trial
Prostate cancer is one of the most common types of cancer. An effective treatment is androgen deprivation therapy (ADT), which lowers testosterone levels to castration levels. However, such low testosterone levels tend to result in a loss of muscle mass and strength.
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Our study investigated the effect of resistance training with or without protein supplementation on muscle mass and strength in prostate cancer patients undergoing ADT.
Exercise and protein ingestion are the main factors that stimulate muscle protein synthesis (the main process driving muscle adaptations such as growth).
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It has been reported that athletes are more likely to consume excessive amounts of alcohol, especially as part of binge-drinking practices in team sports. Can these practices affect muscle protein synthesis?
Muscle growth occurs when muscle protein synthesis exceeds muscle protein breakdown. Resistance exercise stimulates both muscle protein synthesis and breakdown. Ingestion of protein further increases muscle protein synthesis and is needed to achieve positive protein net balance.
In young adults, 20 g of high-quality protein seems optimal to stimulate post-exercise muscle protein synthesis. However, is this also true for older adults?