King Grub
2011-10-12, 09:19
BACKGROUND:
Both protein and caffeine co-ingestion with carbohydrate (CHO) have been suggested to represent effective dietary strategies to further accelerate post-exercise muscle glycogen synthesis in athletes.
PURPOSE:
To assess the impact of protein or caffeine co-ingestion on post-exercise muscle glycogen synthesis rates when optimal amounts of carbohydrate are ingested.
METHODS:
14 male cyclists were studied on 3 different test days. Each test day started with a glycogen depleting exercise session. This was followed by a 6 h recovery period, during which subjects received 1.2 g·kg·h carbohydrate (CHO), or the same amount of carbohydrate with 0.3 g·kg·h of a protein plus leucine mixture (CHO+PRO) or 1.7 mg·kg·h caffeine (CHO+CAF). All drinks were enriched with ]U-C6[ labelled glucose to assess potential differences in the appearance rate of ingested glucose from the gut. Muscle biopsies were collected immediately after cessation of exercise and after 6 h of post-exercise recovery.
RESULTS:
The plasma insulin response was higher in CHO+PRO compared with CHO and CHO+CAF (P<0.01). Plasma glucose responses and glucose appearance rates did not differ between experiments. Muscle glycogen synthesis rates averaged 31±4, 34±4 and 31±4 mmol·kg dw·h in CHO, CHO+PRO and CHO+CAF, respectively (P=NS). In accordance, histochemical analyses did not show any differences between net changes in type I and type II muscle fiber glycogen content between experiments.
CONCLUSION:
Co-ingestion of protein or caffeine does not further accelerate post-exercise muscle glycogen synthesis when ample amounts of carbohydrate (1.2 g·kg·h) are ingested.
Med Sci Sports Exerc. 2011 Oct 7. Impact of Caffeine and Protein on Post-Exercise Muscle Glycogen Synthesis.
Both protein and caffeine co-ingestion with carbohydrate (CHO) have been suggested to represent effective dietary strategies to further accelerate post-exercise muscle glycogen synthesis in athletes.
PURPOSE:
To assess the impact of protein or caffeine co-ingestion on post-exercise muscle glycogen synthesis rates when optimal amounts of carbohydrate are ingested.
METHODS:
14 male cyclists were studied on 3 different test days. Each test day started with a glycogen depleting exercise session. This was followed by a 6 h recovery period, during which subjects received 1.2 g·kg·h carbohydrate (CHO), or the same amount of carbohydrate with 0.3 g·kg·h of a protein plus leucine mixture (CHO+PRO) or 1.7 mg·kg·h caffeine (CHO+CAF). All drinks were enriched with ]U-C6[ labelled glucose to assess potential differences in the appearance rate of ingested glucose from the gut. Muscle biopsies were collected immediately after cessation of exercise and after 6 h of post-exercise recovery.
RESULTS:
The plasma insulin response was higher in CHO+PRO compared with CHO and CHO+CAF (P<0.01). Plasma glucose responses and glucose appearance rates did not differ between experiments. Muscle glycogen synthesis rates averaged 31±4, 34±4 and 31±4 mmol·kg dw·h in CHO, CHO+PRO and CHO+CAF, respectively (P=NS). In accordance, histochemical analyses did not show any differences between net changes in type I and type II muscle fiber glycogen content between experiments.
CONCLUSION:
Co-ingestion of protein or caffeine does not further accelerate post-exercise muscle glycogen synthesis when ample amounts of carbohydrate (1.2 g·kg·h) are ingested.
Med Sci Sports Exerc. 2011 Oct 7. Impact of Caffeine and Protein on Post-Exercise Muscle Glycogen Synthesis.