Effects of dietary L-arginine intake on cardiorespiratory and metabolic adaptation in athletes.
To assess the effect of diet enrichment with L-arginine or supplementation at high doses on physiological adaptation during exercise, 9 athletes followed 3 different diets, each over 3 consecutive days, with a wash-out period of 4 d between training sessions: control diet (CD), 5.5 +/- 0.3 g/d of L-arginine; Diet 1 (rich in L-arginine food), 9.0 +/- 1.1 g/d of L-arginine; and Diet 2 (the same as CD but including an oral supplement of 15 g/d), 20.5 +/- 0.3 g/d of L-arginine. Plasma nitrate levels of each participant were determined on the day after each treatment. Participants performed a submaximal treadmill test (initial speed 10-11 km/hr, work increments 1 km/hr every 4 min until 85-90% VO2max, and passive recovery periods of 2 min). Oxygen uptake and heart rate were monitored throughout the test. Blood lactate concentration ([La-]b) was determined at the end of each stage. Repeated-measures ANOVA and paired Student's t tests were used to compare the various physiological parameters between diets. The level of significance was set at p < .05. [La-]b showed a significant effect at the 5-min time point between CD and Diet 2 (CD 3.0 +/- 0.5 mM, Diet 2 2.5 +/- 0.5 mM, p = .03), but this tendency was not found at higher exercise intensities. No significant differences were observed in any of the cardiorespiratory or plasma nitrate levels. In conclusion, dietary L-arginine intake on the days preceding the test does not improve physiological parameters during exercise.
Bescós
Raul
R
Physiology Laboratory, National Institute of Physical Education, Barcelona, Spain.
Gonzalez-Haro
Carlos
C
Pujol
Pere
P
Drobnic
Franchek
F
Alonso
Eulalia
E
Santolaria
Maria Luisa
ML
Ruiz
Olga
O
Esteve
Marc
M
Galilea
Pedro
P
D000222:Adaptation, Physiological / Q000187:drug effects* / Q000502:physiology; D000293:Adolescent; D000704:Analysis of Variance; D001120:Arginine / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*; D018592:Cross-Over Studies; D019587:Dietary Supplements; D005080:Exercise Test; D005527:Food, Fortified; D006339:Heart Rate / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D019344:Lactic Acid / Q000097:blood*; D008297:Male; D009566:Nitrates / Q000097:blood*; D010101:Oxygen Consumption / Q000187:drug effects* / Q000502:physiology
D009566:Nitrates; D019344:Lactic Acid; D001120:Arginine