Computational protocol: Assessing a commercially available sports drink on exogenous carbohydrate oxidation, fluid delivery and sustained exercise performance

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Protocol publication

[…] Fourteen club level male cyclists were recruited for participation following power calculation assessment (G*Power3, Dusseldorf []). All participants had an endurance training background of at least two years, and did not suffer from diabetes or have known dysglycemia. Before undertaking the study, participants were required to provide written informed consent and satisfactorily complete a health screen questionnaire. Additionally, participants were excluded if consuming other nutritional supplements. Ethical approval for the study was provided by the University of Hertfordshire Life and Medical Sciences Ethics Committee. [...] At least one week prior to experimental trials, participants completed an incremental exercise test to volitional exhaustion for assessment of maximal power output (Wmax) and maximal oxygen consumption (VO2max). All testing was undertaken in the Human Physiology Laboratory, Division of Sport, Health and Exercise, University of Hertfordshire. Upon reporting to the laboratory, the participants’ nude body mass (Seca, model 780, Hamburg, Germany) and height were recorded. Following this, maximal tests were performed on a Computrainer (RaceMate Inc, Seattle, USA) and related Coaching Software program (Comp CS, RaceMate Inc, Seattle, USA). The Computrainer was pre-calibrated and standardised to the body mass and cycle of the participant.Following a 10 minute standardised warm-up at 100 W, an incremental step protocol was then undertaken, with power output progressing by 30 W each 3 minutes until volitional exhaustion. Participants were fitted with an oro-nasal face mask (7920 series, Hans Rudolph Inc., Kansas City, USA) attached to a triple-V digital volume transducer. Respiratory data was recorded throughout exercise using a Metalyzer 3B system online automated gas-analyser in conjunction with Metasoft version 3 software (Cortex Biophysik, Leipzig, Germany). Heart rate (HR) was recorded continuously via radio-telemetry (Polar Electro Oy, Kempele, Finland). Ratings of perceived exertion (RPE) were collected in the final minute of each stage, using the Borg 6–20 subjective exertion scale []. The test concluded when participants reached volitional exhaustion or were unable to maintain the required power output.Maximal power was calculated by adding the final completed workload to the fraction of time spent in the non-completed workload, multiplied by 30 W. Oxygen consumption (VO2) was defined as maximal when two of the following criteria were met: 1) a levelling off of VO2 with increasing workload (increase of no more than 2 ml · kgˉ1 · minˉ1); 2) attainment of maximal predicted heart rate (±10 beats.min-1); and 3) a respiratory exchange ratio (RER) of >1.05. The highest attained VO2, maintained for 20 seconds, was determined to be the VO2max. Participants also undertook a separate habituation trial for both steady state and performance conditions. The characteristics of the participants are shown in Table . [...] Total oxidation rates:Rates of CHOTOT and FATTOT (g · min-1) were calculated from absolute VO2 and VCO2 (L · min-1) utilising the following stoichiometric equations [], with protein oxidation during exercise assumed negligible: CH O TOT = 4.585 VC O 2 3.226 V O 2 FA T TOT = 1.695 V O 2 ‒ 1.701 VC O 2 Exogenous carbohydrate oxidation rates:The rate of CHOEXO (g · min-1) was calculated using the following formula []: CHOEXO = VCO 2 · Exp ‒ Ex p BKG Ing ‒ Ex p BKG · 1 k Where δExp is the 13C-enrichment of expired air throughout the oxidation trial, δIng is the 13C-enrichment of the CHO solution,ExpBKG is the 13C-enrichment of expired air throughout the placebo trial (P) and k is the CO2 produced via the oxidation of 1 g of glucose (k = 0.7467 litres of CO2 per gram of glucose []).The 13C-enrichment was expressed as δ‰ difference between the 13C:12C ratio of the sample and a known laboratory reference standard (PDB) according to the following formula []: δ 13 C = 13 C 12 C of sample 13 C 12 C of standard ‒ 1 · 1 0 3 The rate of CHOENDO was calculated by subtracting CHOEXO from CHOTOT. Substrate oxidation was calculated over the final 90 minutes of exercise (60–150 minutes) due to the earlier capture of 13CO2 in the bicarbonate (HCO3ˉ) pool. It has been reported that dilution in the bicarbonate pool becomes negligible after 60 minutes of exercise, when 100% of the 13CO2 from oxidation is retrieved [,,].Carbohydrate oxidation efficiency:Estimation of carbohydrate oxidation efficiency was determined using the following formula []: CHOEXO efficiency = 100 · CHOEXO CHO ingestion rate Statistical analyses:Statistical analyses were performed using SPSS Statistics for Windows version 19 (SPSS, Chicago, USA). A two-way analysis of variance (ANOVA) with repeated measures design was used to assess for interaction effects between conditions, trials and over time. Where appropriate, a one-way ANOVA was used to assess for differences for relevant experimental measures (e.g.: mean CHOEXO) between trials only. Significant differences were assessed with a student t-test with Bonferoni post hoc adjustments. Where pertinent, pearson chi squared assessment was undertaken (e.g.: gastrointestinal responses). An alpha level of 0.05 was employed for assessment of statistical significance. All data are reported as means ± SE. […]

Pipeline specifications

Software tools G*Power, METASOFT, SPSS
Applications Miscellaneous, GWAS
Chemicals Fructose, Deuterium Oxide