short-duration, high-intensity cycling TT, compared with a placebo and water control. Performance was improved in both the CHO and PLA trials, suggesting there was a placebo effect of ingesting breakfast. This would indicate that with the length and intensity of the exercise used in the current study
Stephen A. Mears, Kathryn Dickinson, Kurt Bergin-Taylor, Reagan Dee, Jack Kay and Lewis J. James
Bryan Saunders, Craig Sale, Roger C. Harris and Caroline Sunderland
To determine whether gastrointestinal (GI) distress affects the ergogenicity of sodium bicarbonate and whether the degree of alkalemia or other metabolic responses is different between individuals who improve exercise capacity and those who do not.
Twenty-one men completed 2 cycling-capacity tests at 110% of maximum power output. Participants were supplemented with 0.3 g/kg body mass of either placebo (maltodextrin) or sodium bicarbonate (SB). Blood pH, bicarbonate, base excess, and lactate were determined at baseline, preexercise, immediately postexercise, and 5 min postexercise.
SB supplementation did not significantly increase total work done (TWD; P = .16, 46.8 · 9.1 vs 45.6 · 8.4 kJ, d = 0.14), although magnitude-based inferences suggested a 63% likelihood of a positive effect. When data were analyzed without 4 participants who experienced GI discomfort, TWD (P = .01) was significantly improved with SB. Immediately postexercise blood lactate was higher in SB for the individuals who improved but not for those who did not. There were also differences in the preexercise-to-postexercise change in blood pH, bicarbonate, and base excess between individuals who improved and those who did not.
SB improved high-intensity-cycling capacity but only with the exclusion of participants experiencing GI discomfort. Differences in blood responses suggest that SB may not be beneficial to all individuals. Magnitude-based inferences suggested that the exercise effects are unlikely to be negative; therefore, individuals should determine whether they respond well to SB supplementation before competition.
Thomas C. Ball, Samuel A. Headley, Paul M. Vanderburgh and John C. Smith
The purpose of this study was to investigate the effect of 7% carbohydrate-electrolyte (CE) drink on sprint capacity immediately following 50 min of high-intensity cycling. After an overnight 12-hr fast, 8 trained male cyclists performed two 50-min simulated time trials on a Monark stationary cycle ergometer. Subjects consumed either the CE or a flavored water placebo (PL) at 10, 20, 30, and 40 min during the time trial. At the conclusion of each 50-min time trial, subjects immediately performed a Wingate Anaerobic Power Test. Peak power, mean power, and minimum power were significantly higher for the CE trials, whereas mean RPE was significantly lower. Mean heart rate and fatigue index were not different between trials. These results suggest that sprint performance following a high-intensity simulated time trial of only 50 min can be improved with periodic consumption of CE during the ride, particularly following an overnight fast, when liver glycogen is likely to be low. These findings have implications for competitive cycling, where sprint capacity at the conclusion of a race is an important determinant of success.
Carl J. Petersen, Marc R. Portus, David B. Pyne, Brian T. Dawson, Matthew N. Cramer and Aaron D. Kellett
Cricketers are often required to play in hot/humid environments with little time for heat adaptation.
We examined the effect of a short 4-d hot/humid acclimation program on classical physiological indicators of heat acclimation.
Male club cricketers were randomly assigned into heat acclimation (ACC, n = 6) or control (CON, n = 6) groups, and 30 min treadmill trials (10 km/h, approx. 30 ± 1.0°C, approx. 65 ± 6% RH) were conducted at baseline and postacclimation. The ACC group completed four high intensity (30–45 min) acclimation sessions on consecutive days at approx. 30°C and approx. 60% RH using a cycle ergometer. The CON group completed matched cycle training in moderate conditions (approx. 20°C, approx. 60% RH). Physiological measures during each treadmill trial included heart rate; core and skin temperatures; sweat Na+, K+ and Cl– electrolyte concentrations; and sweat rate.
After the 4-d intervention, the ACC group had a moderate decrease of -11 (3 to -24 beats/min; mean and 90% CI) in the 30 min heart rate, and moderate to large reductions in electrolyte concentrations: Na+ -18% (–4 to -31%), K+ -15% (0 to -27%), Cl– -22% (-9 to -33%). Both ACC and CON groups had only trivial changes in core and skin temperatures and sweat rate. After the intervention, both groups perceived they were more comfortable exercising in the heat. The 4-d heat intervention had no detrimental effect on performance.
Four 30–45 min high intensity cycle sessions in hot/humid conditions elicited partial heat acclimation. For full heat acclimation a more intensive and extensive (and modality-specific) acclimation intervention is needed for cricket players.
Andrew E. Kilding, Claire Overton and Jonathan Gleave
To determine the effects of ingesting caffeine (CAFF) and sodium bicarbonate (SB), taken individually and simultaneously, on 3-km cycling time-trial (TT) performance.
Ten well-trained cyclists, age 24.2 ± 5.4 yr, participated in this acute-treatment, double-blind, crossover study that involved four 3-km cycling TTs performed on separate days. Before each TT, participants ingested either 3 mg/kg body mass (BM) of CAFF, 0.3 g · kg−1 · BM−1 of SB, a combination of the two (CAFF+SB), or a placebo (PLAC). They completed each 3-km TT on a laboratory-based cycle ergometer, during which physiological, perceptual, and performance measurements were determined. For statistical analysis, the minimal worthwhile difference was considered ~1% based on previous research.
Pretrial pH and HCO3 were higher in SB and CAFF+SB than in the CAFF and PLAC trials. Differences across treatments for perceived exertion and gastric discomfort were mostly unclear. Compared with PLAC, mean power output during the 3-km TT was higher in CAFF, SB, and CAFF+SB trials (2.4%, 2.6%, 2.7% respectively), resulting in faster performance times (–0.9, –1.2, –1.2% respectively). Effect sizes for all trials were small (0.21–0.24).
When ingested individually, both CAFF and SB enhance high-intensity cycling TT performance in trained cyclists. However, the ergogenic effect of these 2 popular supplements was not additive, bringing into question the efficacy of coingesting the 2 supplements before short-duration high-intensity exercise. In this study there were no negative effects of combining CAFF and SB, 2 relatively inexpensive and safe supplements.
Richard Ebreo, Louis Passfield and James Hopker
investigate the impact of GE on high-intensity cycling performance. 4 It has been demonstrated that the estimated anaerobic contribution to cycling time-trial performance is 30% larger during time trials of less than 4000 m when a declining rather than constant GE is assumed. 4 A declining GE and a higher
Lewis A. Gough, Steven Rimmer, Callum J. Osler and Matthew F. Higgins
This study evaluated the ingestion of sodium bicarbonate (NaHCO3) on postexercise acid-base balance recovery kinetics and subsequent high-intensity cycling time to exhaustion. In a counterbalanced, crossover design, nine healthy and active males (age: 23 ± 2 years, height: 179 ± 5 cm, body mass: 74 ± 9 kg, peak mean minute power (Wpeak) 256 ± 45 W, peak oxygen uptake (V̇O2peak) 46 ± 8 ml.kg-1.min-1) performed a graded incremental exercise test, two familiarization and two experimental trials. Experimental trials consisted of cycling to volitional exhaustion (TLIM1) at 100% WPEAK on two occasions (TLIM1 and TLIM2) interspersed by a 90 min passive recovery period. Using a double-blind approach, 30 min into a 90 min recovery period participants ingested either 0.3 g.kg-1 body mass sodium bicarbonate (NaHCO3) or a placebo (PLA) containing 0.1 g.kg-1 body mass sodium chloride (NaCl) mixed with 4 ml.kg-1 tap water and 1 ml.kg-1 orange squash. The mean differences between TLIM2 and TLIM1 was larger for PLA compared with NaHCO3 (-53 ± 53 vs. -20 ± 48 s; p = .008, d = 0.7, CI =-0.3, 1.6), indicating superior subsequent exercise time to exhaustion following NaHCO3. Blood lactate [Bla-] was similar between treatments post TLIM1, but greater for NaHCO3 post TLIM2 and 5 min post TLIM2. Ingestion of NaHCO3 induced marked increases (p < .01) in both blood pH (+0.07 ± 0.02, d = 2.6, CI = 1.2, 3.7) and bicarbonate ion concentration [HCO3 -] (+6.8 ± 1.6 mmo.l-1, d = 3.4, CI = 1.8, 4.7) compared with the PLA treatment, before TLIM2. It is likely both the acceleration of recovery, and the marked increases of acid-base after TLIM1 contributed to greater TLIM2 performance compared with the PLA condition.
Florian Engel, Sascha Härtel, Jana Strahler, Matthias Oliver Wagner, Klaus Bös and Billy Sperlich
This study aimed to determine the effects of a single high-intensity interval training (HIIT) session on salivary cortisol (SC) levels, physiological responses, and performance in trained boys and men. Twenty-three boys (11.5 ± 0.8 years) and 25 men (29.7 ± 4.6 years) performed HIIT (4 consecutive Wingate Anaerobic Tests). SC in boys and men increased after HIIT from 5.55 ± 3.3 nmol/l to 15.13 ± 9.7 nmol/l (+173%) and from 7.07 ± 4.7 nmol/l to 19.19 ± 12.7 nmol/l (+171%), respectively (p < .01). Pretest SC as well as posttest changes were comparable in both groups (both p < .01). Peak blood lactate concentration was significantly lower in boys (12.6 ± 3.5 mmol/l) than in men (16.3 ± 3.1 mmol/l; p < .01). Throughout the HIIT, mean heart rates in boys were higher (p < .001) but relative peak oxygen uptake (ml·min−1·kg−1; p < .05) and performance were lower (p < .001) in boys than in men. HIIT in young athletes is associated with a higher activation of the hormonal stress axis than other types of exercise regimes as described in the literature. This study is the first to show a pronounced SC increase to HIIT in trained boys accompanied by elevated levels of blood lactate concentrations and heart rate suggesting a high cardio-respiratory, metabolic, and hormonal response to HIIT in 11-year-old boys.
David S. Rowlands and Will G. Hopkins
The effect of pre-exercise meal composition on metabolism and performance in cycling were investigated in a crossover study. Twelve competitive cyclists ingested high-fat, high-carbohydrate, or high-protein meals 90 min before a weekly exercise test. The test consisted of a 1-hour pre-load at 55% peak power, five 10-min incremental loads from 55 to 82% peak power (to measure the peak fat-oxidation rate), and a 50-km time trial that included three 1-km and 4-km sprints. A carbohydrate supplement was ingested throughout the exercise. Relative to the high-protein and high-fat meals, the high-carbohydrate meal halved the peak fat-oxidation rate and reduced the fat oxidation across all workloads by a factor of 0.20 to 0.58 (p = .002–.0001). Reduced fat availability may have accounted for this reduction, as indicated by lower plasma fatty acid, lower glycerol, and higher pre-exercise insulin concentrations relative to the other meals (p = .04–.0001). In contrast, fat oxidation following the high-protein meal was similar to that following the high-fat meal. This similarity was linked to evidence suggesting greater lipolysis and plasma fat availability following high-protein relative to high-carbohydrate meals. Despite these substantial effects on metabolism, meal composition had no clear effect on sprint or 50-km performance.
Megan L. Ross, Brian Stephens, Chris R. Abbiss, David T. Martin, Paul B. Laursen and Louise M. Burke
To observe voluntary fluid and carbohydrate intakes and thermoregulatory characteristics of road cyclists during 2 multiday, multiple-stage races in temperate conditions.
Ten internationally competitive male cyclists competed in 2 stage races (2009 Tour of Gippsland, T1, n = 5; 2010 Tour of Geelong, T2, n = 5) in temperate conditions (13.2–15.8°C; 54–80% relative humidity). Body mass (BM) was recorded immediately before and after each stage. Peak gastrointestinal temperature (TGI peak) was recorded throughout each stage. Cyclists recalled the types and volumes of fluid and food consumed throughout each stage.
Although fluid intake varied according to the race format, there were strong correlations between fluid intake and distance across all formats of racing, in both tours (r = .82, r = .92). Within a stage, the relationship between finishing time and fluid intake was trivial. Mean BM change over a stage was 1.3%, with losses >2% BM occurring on 5 out of 43 measured occasions and the fastest competitors incurring lower BM changes. Most subjects consumed carbohydrate at rates that met the new guidelines (30–60 g/h for 2–3 h, ~90 g/h for >3 h), based on event duration. There were consistent observations of TGI peak >39°C during stages of T1 (67%) and T2 (73%) despite temperate environmental conditions.
This study captured novel effects of highintensity stage racing in temperate environmental conditions. In these conditions, cyclists were generally able to find opportunities to consume fluid and carbohydrate to meet current guidelines. We consistently observed high TGI peak, which merits further investigation.