Production of reactive oxygen species (ROS) during muscle contractions is associated with muscle fatigue and damage in the short term and adaptive responses in the long term. When adaptation is inconsequential acute antioxidant supplementation may be able to attenuate muscle fatigue and damage to enhance performance. This study aimed to determine the effects of acute oral N-acetylcysteine (NAC) supplementation on Yo-Yo Intermittent Recovery Test Level 1 (YIRT-L1) performance after repeated bouts of damaging intermittent exercise. In a pair-matched design, 12 recreationally trained men engaged in 6 d of either NAC (n = 6) or placebo (n = 6) supplementation. After a treatment-loading day, participants completed 3 testing sessions, on alternating days, consisting of a preexercise isokinetic dynamometry (IKD) test, a damaging intermittent-exercise protocol, YIRT-L1, and a postexercise IKD test. Another IKD test was completed on the 2 intervening d. NAC treatment resulted in a significant preservation of YIRT-L1 performance (p ≤ .0005). IKD performance significantly deteriorated over time at all contraction speeds, and this deterioration was not influenced by treatment group. Plasma creatine kinase values increased significantly over time (p = .002) and were significantly greater in the NAC group than in the placebo group (p = .029). NAC induced mild gastrointestinal side effects. NAC supplementation may be a useful strategy to enhance performance during short-term competitive situations when adaption is inconsequential. Titration studies to elucidate a treatment dose that enhances performance without inducing side effects are now required.
James N. Cobley, Chris McGlory, James P. Morton and Graeme L. Close
Emma M. Crum, Matthew J. Barnes and Stephen R. Stannard
through an increase in plasma NO (as indicated by increased plasma NO 3 − ) and would increase performance in a time trial (TT). Second, it was predicted that these improvements would be augmented by cosupplementation with the thiol N -acetylcysteine (NAC). Materials and Methods Participants Eight
Leonardo F. Ferreira, Kenneth S. Campbell and Michael B. Reid
N-acetylcysteine (NAC) is a thiol donor with antioxidant properties that has potential use as an ergogenic aid. However, NAC is associated with adverse reactions that limit its use in humans.
The authors evaluated NAC efficacy as a thiol donor before handgrip exercise, measuring changes in serum cysteine and glutathione status and recording adverse reactions in adult subjects across a range of doses.
Healthy individuals ingested NAC capsules (9 ± 2 or 18 ± 4 mg/kg) or solution (0, 35, 70, or 140 mg/kg). Venous blood samples were collected and subjects answered a questionnaire about adverse reactions.
Low doses of NAC (capsules) did not affect plasma cysteine or glutathione or cause adverse reactions. Adverse reactions to NAC solution were predominantly mild and gastrointestinal (GI). Intensity of GI reactions to 140 mg/kg NAC was significantly higher than placebo (in a.u., 0.67 ± 0.16 vs. 0.07 ± 0.04; p < .05). Plasma cysteine concentration increased with NAC dose from 9.3 ± 0.7 μM (placebo) to 65.3 ± 6.7 μM (140 mg/kg); however, there was no difference (p > .05) in plasma cysteine for 70 mg/kg vs. 140 mg/kg. Similar increases were observed for the ratio of cysteine to total cysteine, which was directly related to handgrip exercise performance. Plasma glutathione was elevated and oxidized glutathione diminished (p < .05) with NAC 140 mg/kg vs. placebo.
NAC effects on plasma thiols are maximized by oral administration of 70 mg/kg, a dose that does not cause significant adverse reactions.
Luciano A. Silva, Paulo C.L Silveira, Cléber A. Pinho, Talita Tuon, Felipe Dal Pizzol and Ricardo A. Pinho
The objective of the study was to verify the effect of N-acetylcysteine (NAC) supplementation on parameters of oxidative damage and inflammatory response after high-intensity eccentric exercise (EE). 29 participants with a mean age of 21.3 ± 4 yr, weight of 74.5 ± 7.7 kg, and height of 177.2 ± 6.9 cm were selected and divided randomly into 3 groups: placebo (21 days; n = 8), NAC (21 days; n = 9), and NAC plus placebo (14 days; n = 8). Four participants withdrew from the study for personal reasons. 14 days after starting supplementation, the participants performed EE: 3 sets until exhaustion (elbow flexion and extension on the Scott bench, 80% 1RM). Blood samples were collected before and on the 2nd, 4th, and 7th day after EE. Muscle soreness (MS), lipoperoxidation, protein carbonylation, tumor-necrosis factor-cc(TNF-(), and interleukin 10 (IL-10) were determined. Results showed a significant increase in MS in all the groups on the 2nd day after EE and a decrease in the following days. A significant increase was observed in malondialdehyde and carbonyl levels on the 4th and 7th days after EE in all groups. TNF-EEincreased significantly on the 2nd day after eccentric exercise and decreased in the following days irrespective of NAC supplementation; concentration of IL-10 increased significantly on the 4th day in all groups. Only the supplemented groups maintained high levels of IL-10 on the 7th day after EE. The results suggest that treatment with NAC represents an important factor in the defense against muscle soreness and has different effects on oxidative damage and pro- and anti-inflammatory cytokines.
Mero Antti, Paavo V. Komi, Tapio Korjus, Enrique Navarro and Robert J. Gregor
This study investigated body segment contributions to javelin throwing during the last thrust phases. A 3-D analysis was performed on male and female javelin throwers during the finals of the 1992 Olympic Games in Barcelona. The subjects were videotaped from the right sight of the throwing area by two NAC high-speed cameras operating at 100 frames per second. Both men’s and women’s grip of javelin and body center of mass displayed a curved pathway to the right from the left (bracing) foot during the final foot contact. The position of the body center of mass decreased at the beginning of the final foot contact, but after the decrease period it began to increase. Simultaneously with the increase, the peak joint center speeds occurred in a proper sequence from proximal to distal segments and finally to the javelin at release. Release speed correlated significantly with throwing distance in both male and females.
This investigation analyzed the visual search patterns of novice and expert dance teachers when viewing a live performance of a dance composition. The hypotheses tested were that (a) experts would not differ from novices in the number of eye fixations and duration of each, (b) the number of fixations and duration of each would differ between dances, and (c) expert teachers’ search patterns would differ from those of novice teachers. The subjects were four experts who averaged 25.5 years of teaching, and five novice teachers who averaged 2.4 years. To determine the ocular fixation and scanning patterns of subjects, the NAC Eye Movement Recorder, a corneal reflection technique, was used. The films were analyzed using a computer program designed to collect the data. Two 2 × 2 (expertise and dances) analyses of variance were used to determine the differences in the number of fixations, duration of fixations, and differences of variable between dances. Chi-square was used to determine the location of scan patterns. Results indicated that the level of expertise did not influence the number or duration of each eye fixation, but the task being observed did influence these variables. Individual differences in visual scanning patterns were found among and within both groups.
Rand Wilcox, Travis J. Peterson and Jill L. McNitt-Gray
Probability and Statistics . Stanford, CA : Stanford University Press ; 1960 : 448 – 485 . 15. Cressie NAC , Whitford HJ . How to use the two sample t -test . Biom J . 1986 ; 28 : 131 – 148 . doi:10.1002/bimj.4710280202 10.1002/bimj.4710280202 16. Wilcox RR , Rousselet GA . A guide to robust
Nico Hofman, Jac Orie, Marco J.M. Hoozemans, Carl Foster and Jos J. de Koning
C . Effect of pacing strategy on energy expenditure during a 1500-m cycling time-trial . Med Sci Sports Exerc . 2007 ; 39 : 2212 – 2218 . PubMed doi:10.1249/mss.0b013e318156e8d4 18046193 10.1249/mss.0b013e318156e8d4 22. Hettinga FJ , de Koning JJ , Schmidt LJI , Wind NAC , MacIntosh
Daniela Rodrigues, Cristina Padez and Aristides M. Machado-Rodrigues
23581744 27. Monteiro JL . Caracterização dos Espaços Urbanos na RLVT: O contributo da análise discriminante . Rev Estud Reg—Inst Nac Estatística . 2000 ; 2 ( 1 ): 21 – 46 . 28. Holt NL , Kingsley BC , Tink LN , Scherer J . Benefits and challenges associated with sport participation by
Shohei Shibata, Yuki Inaba, Shinsuke Yoshioka and Senshi Fukashiro
two fingers were obtained using a high-speed camera at 1,000 frames per second (MEMRECAM HX-6; nac Image Technology, Inc., Tokyo, Japan). Conventional Model and Finger Model The “finger model” divides the hand segment into palm, finger, and ball segments (Figure 1a ). The ball is assumed to be a mass