title: Effects of twenty-eight days of beta-alanine and creatine monohydrate supplementation on the physical working capacity at neuromuscular fatigue threshold.
abstract: The purpose of this study was to examine the effects of 28 days of beta-alanine (b-Ala) and creatine monohydrate (CrM) supplementation on the onset of neuromuscular fatigue by using the physical working capacity at neuromuscular fatigue threshold (PWC(FT)) test in untrained men. Fifty-one men (mean age +/- SD = 24.5 +/- 5.3 years) volunteered to participate in this 28-day, double-blind, placebo-controlled study and were randomly assigned to 1 of 4 groups: placebo (PLA; 34 g dextrose; n = 13), CrM (5.25 g CrM plus 34 g dextrose; n = 12), b-Ala (1.6 g b-Ala plus 34 g of dextrose; n = 12), or b-Ala plus CrM (CrBA; 5.25 g CrM plus 1.6 g b-Ala plus 34 g dextrose; n = 14). The supplement was ingested 4 times per day for 6 consecutive days, then twice per day for 22 days before posttesting. Before and after the supplementation, subjects performed a continuous incremental cycle ergometry test while a surface electromyographic signal was recorded from the vastus lateralis muscle to determine PWC(FT). The adjusted mean posttest PWC(FT) values (covaried for pretest PWC(FT) values) for the b-Ala and CrBA groups were greater than those for the PLA group (p < or = 0.05). However, there were no differences between the CrM vs. PLA, CrBA vs. b-Ala, CrM vs. b-Ala, or CrM vs. CrBA groups (p > 0.05). These findings suggested that b-Ala supplementation may delay the onset of neuromuscular fatigue. Furthermore, there appeared to be no additive or unique effects of CrM vs. b-Ala alone on PWC(FT).
authors.affiliation: Department of Health and Exercise Science, University of Oklahoma, Norman, OK 73019, USA. jrstout@ou.edu
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Stout
authors.forename: Joel T
authors.initials: JT
authors.lastname: Cramer
authors.forename: Michelle
authors.initials: M
authors.lastname: Mielke
authors.forename: Joseph
authors.initials: J
authors.lastname: O'Kroy
authors.forename: Don J
authors.initials: DJ
authors.lastname: Torok
authors.forename: Robert F
authors.initials: RF
authors.lastname: Zoeller
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D003401:Creatine / Q000008:administration & dosage* / Q000494:pharmacology; D019587:Dietary Supplements; D004311:Double-Blind Method; D004576:Electromyography; D005947:Glucose / Q000008:administration & dosage; D006801:Humans; D016018:Least-Squares Analysis; D008297:Male; D018763:Muscle Fatigue / Q000187:drug effects* / Q000502:physiology; D010807:Physical Endurance / Q000187:drug effects* / Q000502:physiology; D015091:beta-Alanine / Q000008:administration & dosage* / Q000494:pharmacology
chemical_list: D015091:beta-Alanine; D005947:Glucose; D003401:Creatine