title: Muscle buffer capacity and aerobic fitness are associated with repeated-sprint ability in women.
abstract: In addition to a high aerobic fitness, the ability to buffer hydrogen ions (H+) may also be important for repeated-sprint ability (RSA). We therefore investigated the relationship between muscle buffer capacity (betamin vivo and betamin vitro) and RSA. Thirty-four untrained females [mean (SD): age 19 (1) years, maximum oxygen uptake (VO2peak) 42.3 (7.1) ml x kg(-1) x min(-1)] completed a graded exercise test (GXT), followed by a RSA cycle test (five 6-s sprints, every 30 s). Capillary blood was sampled during the GXT and before and after the RSA test to determine blood pH (pHb) and lactate concentration ([La-]b). Muscle biopsies were taken before (n=34) and after (n=23) the RSA test to determine muscle lactate concentration ([La-]i), hydrogen ion concentration ([H+]i) pHi, betamin vivo and betamin vitro. There were significant correlations between work decrement (%) and betamin vivo (r=-0.72, P<0.05), VO2peak (r=-0.62, P<0.05), lactate threshold (LT) (r=-0.56, P<0.05) and changes in [H+]i (r=0.41, P<0.05). There were however, no significant correlations between work decrement and betamin vitro, or changes in [La-]i, or [La-]b. There were also no significant correlations between total work (J x kg(-1)) during the RSA test and betamin vitro, betamin vivo, or changes in [La-]i, pHi, [La-]b, or pHb. There were significant correlations between total work (J x kg(-1)) and both VO2peak (r=0.60, P<0.05) and LT(r=0.54, P<0.05). These results support previous research, identifying a relationship between RSA and aerobic fitness. This study is the first to identify a relationship between betamin vivo and RSA. This suggests that the ability to buffer H+ may be important for maintaining performance during brief, repeated sprints.
authors.affiliation: Team Sport Research Group, School of Human Movement and Exercise Science, The University of Western Australia, WA 6009 Crawley, Australia. dbishop@cyllene.uwa.edu.au
authors.forename: David
authors.initials: D
authors.lastname: Bishop
authors.forename: Johann
authors.initials: J
authors.lastname: Edge
authors.forename: Carmel
authors.initials: C
authors.lastname: Goodman
mesh_terms: D000328:Adult; D015308:Anaerobic Threshold / Q000502:physiology; D001642:Bicycling / Q000502:physiology*; D001784:Blood Gas Analysis; D002021:Buffers; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000378:metabolism; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000502:physiology*; D010809:Physical Fitness / Q000502:physiology*; D000091402:Prohibitins; D011659:Pulmonary Gas Exchange
chemical_list: D002021:Buffers; C000717328:PHB protein, human; D000091402:Prohibitins; D019344:Lactic Acid