title: The effects of 3000-m swimming on subsequent 3-h cycling performance: implications for ultraendurance triathletes.
abstract: The purpose of this study was to examine the physiological effects of 3000-m swimming on subsequent 3-h cycling time trial performance in ultraendurance triathletes. Eight highly trained ultraendurance triathletes [mean (SEM) age 34 (2) years, body fat 12.5 (0.8)%, maximum oxygen consumption 63.2 (2.1) ml x kg(-1) x min(-1)] completed two randomly assigned trials 1 week apart. The swim/bike trial (SB) involved 3000 m of swimming [min:s 52:28 (1:48)] immediately followed by a 3-h cycling performance at a self-selected time-trial pace. The control trial (CON) consisted of an identical 3-h cycling time trial but without prior swimming. Subjects consumed an 8% carbohydrate (CHO)/electrolyte beverage during both trials at the rate of 60 g CHO x h(-1) and 1 l x h(-1). No significant differences were evident between CON and SB on the dependent measures (CON vs. SB): power output [W, 222 (14) W vs. 212 (13) W], heart rate [fc, 147 (5) beats x min(-1) vs. 143 (4) beats min(-1); %fcmax 80.0 (1.6)% vs. 78.4 (1.5)%], oxygen uptake [3.10 (0.12) l x min(-1) vs. 2.97 (0.15) l x min(-1)], minute ventilation [82.5 (4.4) l x min(-1) vs. 77.3 (3.7) l x min(-1)], rating of perceived exertion [14.6 (0.4) vs. 14.0 (0.1)], blood lactate [6.1 (0.5) mmol x l(-1) vs. 4.8 (0.5) mmol x l(-1)], and blood glucose [5.0 (0.2) mmol x l(-1) vs. 5.3 (0.1) mmol x l(-1); all non-significant at the P>0.05 level]. However, the CON respiratory exchange ratio was significantly greater than for SB [0.91 (0.01) vs. 0.89 (0.01); P<0.05], suggesting that the SB trial required a greater reliance on lipid as a fuel substrate. Hence, the main finding in the present study was that 3000 m of swimming had no significant performance effect (in terms of W) on subsequent 3-h cycling performance in ultraendurance triathletes.
authors.affiliation: J.M. Buchanan Exercise Science Laboratory, School of Human Kinetics, University of British Columbia, Vancouver, Canada.
authors.forename: P B
authors.initials: PB
authors.lastname: Laursen
authors.forename: E C
authors.initials: EC
authors.lastname: Rhodes
authors.forename: R H
authors.initials: RH
authors.lastname: Langill
mesh_terms: D000328:Adult; D001628:Beverages; D001642:Bicycling / Q000502:physiology*; D001786:Blood Glucose / Q000378:metabolism; D002241:Carbohydrates / Q000008:administration & dosage; D004573:Electrolytes / Q000008:administration & dosage; D006339:Heart Rate; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D008297:Male; D010101:Oxygen Consumption; D010807:Physical Endurance / Q000502:physiology*; D012119:Respiration; D013550:Swimming / Q000502:physiology*
chemical_list: D001786:Blood Glucose; D002241:Carbohydrates; D004573:Electrolytes; D019344:Lactic Acid