title: The impact of intensified training with a high or moderate carbohydrate feeding strategy on resting and exercise-induced oxidative stress.
abstract: OBJECTIVE
  This study investigated the impact of intensified training (IT) and carbohydrate (CHO) supplementation on resting and exercise-induced oxidative stress.
  
  
  METHODS
  Male cyclists (n = 13, mean ± SD: age 25 ± 6 years; [Formula: see text] 72 ± 5 ml/kg/min) undertook two 9 day periods of endurance-based IT. In a counter-balanced, crossover and double-blinded study design, participants completed IT whilst ingesting high (H-CHO) or moderate (M-CHO) CHO beverages before (H-CHO: 24 g vs.
  2 g), during (H-CHO: 60 g/h vs.
  20 g/h) and after training sessions (H-CHO: 44 g vs.
  10 g). Participants completed fasted performance trials without CHO on days 2, 6 and 10. Blood samples were taken before and immediately after exercise to assess plasma oxidative stress.
  
  
  RESULTS
  Resting thiol (-SH) and catalase (CAT) activities decreased following 6 days of IT, independent of CHO condition [-SH (μM oxidised NADPH): H-CHO-14.0 ± 18.8, M-CHO-20.4 ± 20.3 and CAT (nmol/min/ml): H-CHO 12.5 ± 12.5, M-CHO 6.0 ± 4.5; all p < 0.05]. Resting total antioxidant capacity (TAC) was reduced after IT in M-CHO. All exercise bouts elicited significant increases in CAT, TAC, protein carbonylation (PC) and lipid hydroperoxides (LOOH), independent of CHO condition (p < 0.05). The magnitude of increase in PC and LOOH was greater on days 6 and 10 compared to day 2 in both conditions.
  
  
  CONCLUSIONS
  Short-term IT caused reductions in resting antioxidant capacity in trained cyclists. Exercise-induced increases in PC and LOOH were exaggerated as a result of IT; however, these responses were independent of carbohydrate intake before, during and after the preceding IT sessions.
authors.affiliation: School of Sport, Exercise and Health Sciences, Loughborough University, Leicestershire, LE11 3TU, England, UK, a.wadley@worc.ac.uk.
authors.forename: Alex J
authors.initials: AJ
authors.lastname: Wadley
authors.forename: Sophie C
authors.initials: SC
authors.lastname: Killer
authors.forename: Ida S
authors.initials: IS
authors.lastname: Svendsen
authors.forename: Michael
authors.initials: M
authors.lastname: Gleeson
mesh_terms: D000328:Adult; D000339:Affect / Q000187:drug effects; D015308:Anaerobic Threshold; D000975:Antioxidants / Q000378:metabolism; D001642:Bicycling / Q000502:physiology*; D002374:Catalase / Q000097:blood; D018592:Cross-Over Studies; D004040:Dietary Carbohydrates / Q000494:pharmacology*; D004311:Double-Blind Method; D006801:Humans; D015227:Lipid Peroxidation / Q000187:drug effects; D008297:Male; D018384:Oxidative Stress / Q000187:drug effects*; D064797:Physical Conditioning, Human / Q000379:methods*; D050050:Protein Carbonylation; D012146:Rest / Q000502:physiology*; D013438:Sulfhydryl Compounds / Q000097:blood; D055815:Young Adult
chemical_list: D000975:Antioxidants; D004040:Dietary Carbohydrates; D013438:Sulfhydryl Compounds; D002374:Catalase
references.citation: J Sports Med Phys Fitness. 1998 Dec;38(4):281-5
references.pmid: 9973769
references.citation: Free Radic Biol Med. 2008 Jan 15;44(2):142-52
references.pmid: 18191750
references.citation: Biochem Biophys Res Commun. 2000 Jul 5;273(2):729-35
references.pmid: 10873672
references.citation: Neurochem Int. 2005 Jun;46(8):635-40
references.pmid: 15863241
references.citation: Brain Behav Immun. 2014 Aug;40:182-90
references.pmid: 24675034
references.citation: Anal Biochem. 1985 Oct;150(1):76-85
references.pmid: 3843705
references.citation: Biogerontology. 2005;6(1):71-5
references.pmid: 15834665
references.citation: Scand J Med Sci Sports. 2008 Feb;18(1):67-76
references.pmid: 17346286
references.citation: Physiol Rev. 2008 Oct;88(4):1243-76
references.pmid: 18923182
references.citation: Free Radic Biol Med. 1997;23(3):361-6
references.pmid: 9214571
references.citation: Med Sci Sports Exerc. 2011 Aug;43(8):1552-60
references.pmid: 21266928
references.citation: Free Radic Biol Med. 2008 Jan 15;44(2):126-31
references.pmid: 18191748
references.citation: Med Sci Sports Exerc. 2009 Mar;41(3):709-31
references.pmid: 19225360
references.citation: J Appl Physiol (1985). 2004 Oct;97(4):1245-53
references.pmid: 15155717
references.citation: J Nutr. 2004 Jan;134(1):128-31
references.pmid: 14704304
references.citation: Can J Appl Physiol. 2005 Apr;30(2):186-95
references.pmid: 15981787
references.citation: Int J Sports Med. 2007 Nov;28(11):921-7
references.pmid: 17497585
references.citation: Free Radic Biol Med. 2007 Sep 15;43(6):901-10
references.pmid: 17697935
references.citation: Free Radic Res. 2003 Aug;37(8):835-40
references.pmid: 14567443
references.citation: J Sports Sci. 2010 Feb;28(3):309-17
references.pmid: 20077275
references.citation: J Physiol. 2011 May 1;589(Pt 9):2119-27
references.pmid: 21041533
references.citation: Sports Med. 2014 May;44 Suppl 1:S25-33
references.pmid: 24791914
references.citation: Can J Appl Physiol. 2003 Aug;28(4):588-604
references.pmid: 12904636
references.citation: J Appl Physiol (1985). 2001 Mar;90(3):1031-5
references.pmid: 11181616
references.citation: J Sports Sci. 2017 Jul;35(14 ):1402-1410
references.pmid: 26406911
references.citation: J Appl Physiol (1985). 2004 Apr;96(4):1331-40
references.pmid: 14660506
references.citation: Eur J Appl Physiol. 2014;114(7):1483-92
references.pmid: 24719046
references.citation: Int J Sports Med. 2006 Feb;27(2):87-93
references.pmid: 16475052
references.citation: Int J Sport Nutr Exerc Metab. 2007 Oct;17(5):478-90
references.pmid: 18046057
references.citation: J Sports Sci. 1997 Jun;15(3):353-63
references.pmid: 9232561
references.citation: Int J Sports Med. 2007 Jan;28(1):21-5
references.pmid: 17024638
references.citation: Free Radic Res. 2015 Mar;49(3):290-8
references.pmid: 25547896
references.citation: Anal Biochem. 1996 Jul 15;239(1):70-6
references.pmid: 8660627
references.citation: J Lipid Res. 1989 Apr;30(4):627-30
references.pmid: 2754343
references.citation: Clin Chem. 1998 Jun;44(6 Pt 1):1309-15
references.pmid: 9625058
references.citation: Free Radic Res. 2005 Nov;39(11):1241-8
references.pmid: 16298751
references.citation: J Appl Physiol (1985). 2008 Mar;104(3):853-60
references.pmid: 18006866
references.citation: Med Sci Sports Exerc. 1995 Sep;27(9):1292-301
references.pmid: 8531628
references.citation: Free Radic Biol Med. 1999 Jul;27(1-2):69-74
references.pmid: 10443921
references.citation: Behav Res Methods. 2007 May;39(2):175-91
references.pmid: 17695343
references.citation: J Appl Physiol (1985). 2011 Jul;111(1):206-11
references.pmid: 21493722
references.citation: J Appl Physiol (1985). 2008 Jun;104(6):1611-7
references.pmid: 18420715