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Methods continued

Following is some of the methods section from the article: Hadjicharalambous, M., Georgiades, E., Kilduff, L. P., Turner, A. P., Tsofliou, F. and Pitsiladis, Y. P. (2006) Influence of caffeine on perception of effort, metabolism and exercise performance following a high-fat meal, Journal of Sports Sciences, 24:8,875-887.

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Methods stage Part of the method Critical questions


All exercise tests were carried out between 16:00 and 21:00 h following a 4 h fast, where water was allowed ad libitum. The experimental protocols for Experiment 1 and Experiment 2 are shown in Figure 1.
Figure 1

Figure 1. Schematic illustration of the experimental protocols in Experiment 1 (top panel) and Experiment 2 (bottom panel). HR=heart rate, RPE=rating of perceived exertion, Dysp=dyspnoea

Participants reported to the laboratory 1½ h before the start of exercise, and on the two fat trials consumed capsules containing caffeine or placebo, 3 h after consuming the fat meal. Once bodymass was measured, participants were seated comfortably with their right hand and forearm immersed for 15 min in water at 42–44°C, to achieve arterialization of the venous blood (Forster, Dempsey, Thomson, Vidruk, & DoPico, 1972). Following this, an 18G venous cannula was introduced into a superficial vein on the dorsal surface of the heated hand and a resting blood sample (~10 ml) was obtained. For Experiment 1, further blood samples were obtained at 10 min intervals during the constant-load phase, at the end of the ramp, and at 5 and 10 min postexercise. For Experiment 2, further blood samples were obtained at 15 min intervals throughout exercise until the 90min time-point and at exhaustion. In Experiment 2, participants were transferred to the climatic chamber (ambient temperature 10.2, s = 0.2°C; relative humidity 69.8, s = 1.0%; velocity of approximately 3.6ms-1) and began exercise within 1 min of entering. The exercise intensity and ambient temperature in Experiment 2 were chosen to induce fatigue that would most likely be due to muscle glycogen depletion, rather than the result of some failure in thermoregulation (Galloway & Maughan, 1997). The cannula was kept patent by a slow (~0.5 mlmultiplied bymin-1) infusion of isotonic saline between samples during both experiments. Arterialization of the venous blood was maintained throughout exercise by heating the hand using an infrared lamp. In Experiment 2, participants ingested
7.14 gmultiplied bykg-1 and 2.14 gmultiplied bykg-1 body mass of water at rest and every 15 min throughout exercise, respectively. The participants were asked to maintain a pedal cadence of 60–80 revmultiplied bymin-1 throughout the test; exhaustion was defined as the point at which the participant could no longer maintain the pedal cadence above 60 revmultiplied bymin-1.

For Experiment 1, gas exchange variables were determined breath-by-breath using previously derived algorithms (Beaver, Wasserman, & Whipp, 1973). Respired volumes were measured using a bidirectional turbine volume transducer (VMM, Alpha Technologies, Laguna Niguel, USA), calibrated using a high-precision 3-litre syringe (Hans Rudolph, Kansas City, MO, USA). Respired gas concentrations were measured every 20 ms by a quadrupole mass spectrometer (QP9000, Morgan Medical, Gillingham, Kent, UK), which was calibrated against two precision-analysed gas mixtures. For Experiment 2, expired gas was collected in Douglas bags for 5min at rest, and thereafter 1min collections were obtained every 15min during exercise. Expired gas was analysed within 5 min of collection for [O2] (Servomex 570A, East Sussex, UK) and [CO2] (Servomex 1400 B4, East Sussex, UK), volume (dry gas meter, Harvard Apparatus Ltd, Hertfordshire, UK) and temperature (C6600 10-Channel Microprocessor, Comark, Hertfordshire, UK). All gas volumes were corrected to STPD. Barometric pressure was measured using a standard mercury barometer. Oxygen uptake (VO2), carbon dioxide production (VCO2), ventilation (VE) and respiratory exchange ratio (RER) were subsequently determined and, consequently, the rates of fuel oxidation and energy expenditure were estimated. Energy expenditure was calculated for each time-point using the following equation (Ravussin et al., 1985):

energy expenditure (kcalmultiplied bymin-1)
= {4:686 + [(RER - 0:707) / 0.293] x =0.361} x VO2

For both experiments, the participants were asked to rate “shortness of breath”(breathlessness/dyspnoea) and "leg effort" (leg exertion) using Borg’s 6–20 RPE scale (Borg, 1982) every 10 min during exercise until exhaustion. Heart rate (Polar Sport Tester, Polar Electro Oy, Finland) was also recorded every 10min during exercise until exhaustion. Following exercise in Experiment 2, participants were weighed and loss of body mass was calculated, after correcting for water consumed during exercise. Time to exhaustion was recorded, but withheld from the participant until all trials had been completed and the participant had answered the postintervention questionnaire. Participants were asked: (1) to predict the order of treatments received during the study; (2) to nominate the treatment they perceived produced their best performance; and (3) to indicate which trial they found the most difficult.

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Yes, it provides a clear visual summary of the experiments.

No, but this indicates the experimental procedure was consistently maintained between subjects.

Energy expenditure, heart rate, body mass and blood composition.

To determine whether the treatment results are significantly different from the control results

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