Decrease in respiratory quotient during exercise following L-carnitine supplementation.
This study was undertaken to determine the effects of L-carnitine addition to the diet during submaximal exercise in endurance-trained humans. Ten subjects (VO2max: 62 ml.kg-1.min-1) performed a control test (C) (45 min of cycling at 66% of VO2max) followed by 60 min of recovery in a sitting position. Each subject repeated this trial after 28 days of placebo (P) and L-carnitine (L-C) treatment (double-blinded cross-over design). The dose of each treatment was 2 g/day. There were no differences between the C and P tests. The respiratory quotient was lower (p less than 0.05) with treatment than with P or C during exercise. In addition, oxygen uptake, heart rate, blood glycerol, and resting plasma free fatty acid concentrations presented a nonsignificant trend toward higher values in L-C than in the C or P groups. These observations suggest an increased lipid utilization by muscle during exercise in the L-C-treated group. This effect has further possibilities for improving performance during submaximal exercise.
Gorostiaga
E M
EM
Association Sport-Biologie, Lyone, France.
Maurer
C A
CA
Eclache
J P
JP
D000328:Adult; D002331:Carnitine / Q000494:pharmacology*; D004311:Double-Blind Method; D015444:Exercise; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D010806:Physical Education and Training; D010807:Physical Endurance; D012119:Respiration / Q000187:drug effects*
D002331:Carnitine