Muscle carnitine after strenuous endurance exercise.
The effect of very long endurance exercise on muscle carnitine was studied. Eighteen cross-country skiers took part in a race in the Alps (average inspired partial pressure of O2 100-110 Torr) that lasted on average 13 h 26 min. Carnitine intake, evaluated for 2 wk before the event, was 50 +/- 4 (SE) mg/day. Muscle (vastus lateralis) total carnitine concentration, measured twice with a 2-yr interval on eight rested subjects, did not change with time (17 vs. 16 mumol/g dry wt, NS) but showed consistent interindividual differences (range 12-22, P = 0.001) with no correlation with intake. After exercise, total muscle carnitine was unaltered (from 17.9 +/- 1.0 at rest to 18.3 +/- 0.8 mumol/g dry wt postexercise in the 15 subjects who completed the race, NS), but muscle free carnitine decreased 20% (from 14.9 +/- 0.8 mumol/g, P = 0.01) and short-chain acylcarnitine increased 108% (from 3.5 +/- 0.4 mumol/g, P = 0.01). These results suggest that carnitine deficiency will probably not result from strenuous aerobic exercise in trained subjects who consume a moderate amount of carnitine in their food.
Decombaz
J
J
Nestec Limited, Research Centre, Vers-chez-les-Blanc, Lausanne, Switzerland.
Gmuender
B
B
Sierro
G
G
Cerretelli
P
P
D000328:Adult; D000531:Altitude; D002331:Carnitine / Q000008:administration & dosage / Q000172:deficiency / Q000378:metabolism*; D004032:Diet; D002149:Energy Intake; D015444:Exercise / Q000502:physiology; D006801:Humans; D008297:Male; D009132:Muscles / Q000378:metabolism*; D010807:Physical Endurance / Q000502:physiology*; D012865:Skiing
D002331:Carnitine