Fat adaptation followed by carbohydrate restoration increases AMPK activity in skeletal muscle from trained humans

Sep 20, 2008Journal of applied physiology (Bethesda, Md. : 1985)

Switching from fat to carbs increases energy-regulating enzyme activity in muscles of trained people

AI simplified

Circadian Biology on OpenScience ↗PubMed ↗DOI ↗

Abstract

Fat-adapt increased resting muscle triglyceride levels and AMPK-alpha1 and -alpha2 activity compared to a high-carbohydrate diet.

Muscle biopsies revealed higher triglyceride levels after Fat-adapt (P < 0.05).
Resting AMPK-alpha1 and -alpha2 activity was significantly elevated after Fat-adapt (P = 0.02 and P = 0.05, respectively).
The respiratory exchange ratio during exercise was lower after Fat-adapt (P < 0.01).
Muscle glycogen utilization was decreased during exercise after Fat-adapt (P < 0.05).
Exercise increased AMPK-alpha1 activity after the high-carbohydrate diet but not after Fat-adapt (P = 0.03).
Post-exercise pACC at Ser221 was higher after Fat-adapt compared to the high-carbohydrate diet (P = 0.02).

AI simplified

We have previously reported that 5 days of a high-fat diet followed by 1 day of high-carbohydrate intake (Fat-adapt) increased rates of fat oxidation and decreased rates of muscle glycogenolysis during submaximal cycling compared with consumption of an isoenergetic high-carbohydrate diet (HCHO) for 6 days (Burke et al. J Appl Physiol 89: 2413-2421, 2000; Stellingwerff et al. Am J Physiol Endocrinol Metab 290: E380-E388, 2006). To determine potential mechanisms underlying shifts in substrate selection, eight trained subjects performed Fat-adapt and HCHO. On day 7, subjects performed 1-h cycling at 70% peak O2 uptake. Muscle biopsies were taken immediately before and after exercise. Resting muscle glycogen content was similar between treatments, but muscle triglyceride levels were higher after Fat-adapt (P < 0.05). Resting AMPK-alpha1 and -alpha2 activity was higher after Fat-adapt (P = 0.02 and P = 0.05, respectively), while the phosphorylation of AMPK's downstream target, acetyl-CoA carboxylase (pACC at Ser221), tended to be elevated after Fat-adapt (P = 0.09). Both the respiratory exchange ratio (P < 0.01) and muscle glycogen utilization (P < 0.05) were lower during exercise after Fat-adapt. Exercise increased AMPK-alpha1 activity after HCHO (P = 0.03) but not Fat-adapt. Exercise was associated with an increase in pACC at Ser221 for both dietary treatments (P < 0.05), with postexercise pACC Ser221 higher after Fat-adapt (P = 0.02). In conclusion, compared with HCHO, Fat-adapt increased resting muscle triglyceride stores and resting AMPK-alpha1 and -alpha2 activity. Fat-adapt also resulted in higher rates of whole body fat oxidation, reduced muscle glycogenolysis, and attenuated the exercise-induced rise in AMPK-alpha1 and AMPK-alpha2 activity compared with HCHO. Our results demonstrate that AMPK-alpha1 and AMPK-alpha2 activity and fuel selection in skeletal muscle in response to exercise can be manipulated by diet and/or the interactive effects of diet and exercise training.

Full Text

Full text is available at the source.

View full text ↗

Fat adaptation followed by carbohydrate restoration increases AMPK activity in skeletal muscle from trained humans

Abstract

Full Text

You found one interesting study. We’ll send the next 7.

what lands in your inbox each week:

Recent issues from the circadian biology brief

Abstract

Full Text

Related papers

You found one interesting study. We’ll send the next 7.

what lands in your inbox each week:

Recent issues from the circadian biology brief