title: Acute l-arginine supplementation increases muscle blood volume but not strength performance.
abstract: l-Arginine (L-arg) is an amino acid precursor to nitric oxide (NO). Dietary supplements containing L-arg have been marketed with the purpose of increasing vasodilation, thereby elevating blood flow to the exercising muscle and enhancing the metabolic response to exercise. Our goal was to identify the acute effect of L-arg supplementation on biceps strength performance, indicators of NO production (nitrite and nitrate - NOx), and muscle blood volume (Mbv) and oxygenation (Mox) during recovery from 3 sets of resistance exercise. Fifteen males participated in a randomized, double-blind, placebo-controlled study. After withdrawing resting blood samples, the subjects were supplemented with 6 g of L-arg (ARG) or placebo (PLA). Monitoring of Mbv and Mox with near-infrared spectroscopy began 30 min after supplementation and lasted for 60 min. The exercise protocol (3 sets of 10 maximal voluntary contractions of isokinetic concentric elbow extension at 60°·s(-1), 2-min rest between sets) was initiated 80 min after supplementation. Blood samples were drawn at 30, 60, 90, and 120 min after supplementation. Repeated measures ANOVA showed that Mbv significantly (p ≤ 0.05) increased in ARG compared with the PLA during the recovery period of each set of resistance exercise. NOx, Mox, peak torque, total work, and set total work were not significantly different between groups. We found that acute L-arg supplementation increases Mbv during recovery from sets of resistance exercise with no increase in strength performance. It is still premature to recommend nutritional supplements containing L-arg as an ergogenic aid to increase muscle strength during resistance training in healthy subjects.
authors.affiliation: Gama Filho University, Rio de Janeiro, Brazil. alvares@iq.ufrj.br
authors.forename: Thiago Silveira
authors.initials: TS
authors.lastname: Alvares
authors.forename: Carlos Adam
authors.initials: CA
authors.lastname: Conte
authors.forename: Vânia Margaret Flosi
authors.initials: VM
authors.lastname: Paschoalin
authors.forename: Joab Trajano
authors.initials: JT
authors.lastname: Silva
authors.forename: Cláudia de Mello
authors.initials: Cde M
authors.lastname: Meirelles
authors.forename: Yagesh N
authors.initials: YN
authors.lastname: Bhambhani
authors.forename: Paulo Sergio Chagas
authors.initials: PS
authors.lastname: Gomes
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001120:Arginine / Q000008:administration & dosage* / Q000097:blood; D015415:Biomarkers / Q000097:blood; D001696:Biomechanical Phenomena; D001810:Blood Volume / Q000187:drug effects*; D001938:Brazil; D019587:Dietary Supplements; D004311:Double-Blind Method; D006801:Humans; D008297:Male; D009119:Muscle Contraction; D053580:Muscle Strength / Q000187:drug effects*; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000187:drug effects* / Q000378:metabolism; D009566:Nitrates / Q000097:blood; D009569:Nitric Oxide / Q000378:metabolism; D009573:Nitrites / Q000097:blood; D010101:Oxygen Consumption / Q000187:drug effects; D020127:Recovery of Function; D012039:Regional Blood Flow / Q000187:drug effects; D055070:Resistance Training; D019265:Spectroscopy, Near-Infrared; D013997:Time Factors; D019415:Torque; D034941:Upper Extremity; D014664:Vasodilation / Q000187:drug effects; D055815:Young Adult
chemical_list: D015415:Biomarkers; D009566:Nitrates; D009573:Nitrites; D009569:Nitric Oxide; D001120:Arginine