Amino acid metabolism after intense exercise

Abstract

We studied postexercise amino acid metabolism, in the whole body and across the forearm. Seven volunteers were infused with L-[alpha-15N]lysine and L-[1-13C]-leucine twice [one time during 3 h after cycle exercise (75% VO2max), and one time in the resting state]. Whole body protein breakdown was estimated from dilution of L-[alpha-15N]lysine and L-[1-13C]ketoisocaproic acid (KIC) enrichments in plasma. Leucine oxidation was calculated from 13CO2 enrichments in expired air. Whole body protein breakdown was not increased above resting levels during the recovery period. Leucine oxidation was decreased after exercise (postexercise 13 +/- 2.3 vs. resting 19 +/- 3.2 mumol.kg-1.h-1; P less than 0.02), while nonoxidative leucine disposal was increased (115 +/- 6.1 vs. 103 +/- 5.6 micrograms.kg-1.min-1; P less than 0.02). After exercise, forearm net lysine balance was unchanged (87 +/- 25 vs. 93 +/- 28 nmol.100 ml-1.min-1), but there were decreases in forearm muscle protein degradation (219 +/- 51 vs. 356 +/- 85 nmol.100 ml-1.min-1; P less than 0.05) and synthesis (132 +/- 41 vs. 255 +/- 69 nmol.100 ml-1.min-1; P less than 0.01). In conclusion, after exercise 1) whole body protein degradation is not increased, 2) leucine disposal is directed away from oxidative and toward nonoxidative pathways, 3) forearm protein synthesis is decreased. Postexercise increases in whole body protein synthesis occur in tissues other than nonexercised muscle.

Recovery of skeletal muscle mass after extensive injury: positive effects of increased contractile activity

“…The basal activity of AMPK increased in human skeletal muscle in response to endurance training, at least 15 h after the last exercise bout (18). This is a surprising result because increased basal AMPK activity would slow down the increase in muscle protein synthesis commonly reported during the recovery from endurance exercise (10). Although there are discrepancies between our results and those reported previously in human muscle (18), the decreased AMPK phosphorylation reported in the present study after running exercise may have played a physiological role during this period in enhancing the activity of the mTOR pathway, particularly in Reg muscles.…”

The Mediterranean Diet Adequacy Index in Sports Participants

“…For very active adolescents, protein intake in the range between 1.70 and 2.12 g/kg body weight has been proposed. This corresponds to 12-15% of expended daily energy [34].…”

“…When carbohydrate is scarce, the muscle uses the branched amino acids (leucine, valine, and isoleucine) as an energy source. There is an increase of protein degradation in the body after 2 h of intense exercise beyond 75% of VO 2 max [26,34].…”

Level of dietary protein impacts whole body protein turnover in trained males at rest

“…doi:10.1016/j.metabol.2005. 10.012 after exercise [16,18]. Leucine oxidation increases during exercise in an intensity-dependent manner and may contribute 2% to 6% of total energy expended during an exercise session [2,3,13,19,20].…”