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Purpose: To determine effects of intensified training (IT) and carbohydrate supplementation on overreaching and immunity., Methods: In a randomized, double-blind, crossover design, 13 male cyclists (age 25 ± 6 years, VO2max 72 ± 5 ml/kg/min) completed two 8-day periods of IT. On one occasion, participants ingested 2 % carbohydrate (L-CHO) beverages before, during and after training sessions. On the second occasion, 6 % carbohydrate (H-CHO) solutions were ingested before, during and after training, with the addition of 20 g of protein in the post-exercise beverage. Blood samples were collected before and immediately after incremental exercise to fatigue on days 1 and 9., Results: In both trials, IT resulted in decreased peak power (375 ± 37 vs. 391 ± 37 W, P < 0.001), maximal heart rate (179 ± 8 vs. 190 ± 10 bpm, P < 0.001) and haematocrit (39 ± 2 vs. 42 ± 2 %, P < 0.001), and increased plasma volume (P < 0.001). Resting plasma cortisol increased while plasma ACTH decreased following IT (P < 0.05), with no between-trial differences. Following IT, antigen-stimulated whole blood culture production of IL-1α was higher in L-CHO than H-CHO (0.70 (95 % CI 0.52-0.95) pg/ml versus 0.33 (0.24-0.45) pg/ml, P < 0.01), as was production of IL-1β (9.3 (95 % CI 7-10.4) pg/ml versus 6.0 (5.0-7.8) pg/ml, P < 0.05). Circulating total leukocytes (P < 0.05) and neutrophils (P < 0.01) at rest increased following IT, as did neutrophil:lymphocyte ratio and percentage CD4+ lymphocytes (P < 0.05), with no between-trial differences., Conclusion: IT resulted in symptoms consistent with overreaching, although immunological changes were modest. Higher carbohydrate intake was not able to alleviate physiological/immunological disturbances.

Unlabelled: It is possible that dietary nitrate (NO3 (-)) supplementation may improve both physical and cognitive performance via its influence on blood flow and cellular energetics., Purpose: To investigate the effects of dietary NO3 (-) supplementation on exercise performance and cognitive function during a prolonged intermittent sprint test (IST) protocol, which was designed to reflect typical work patterns during team sports., Methods: In a double-blind randomised crossover study, 16 male team-sport players received NO3 (-)-rich (BR; 140 mL day(-1); 12.8 mmol of NO3 (-)), and NO3 (-)-depleted (PL; 140 mL day(-1); 0.08 mmol NO3 (-)) beetroot juice for 7 days. On day 7 of supplementation, subjects completed the IST (two 40-min "halves" of repeated 2-min blocks consisting of a 6-s "all-out" sprint, 100-s active recovery and 20 s of rest), on a cycle ergometer during which cognitive tasks were simultaneously performed., Results: Total work done during the sprints of the IST was greater in BR (123 ± 19 kJ) compared to PL (119 ± 17 kJ; P < 0.05). Reaction time of response to the cognitive tasks in the second half of the IST was improved in BR compared to PL (BR first half: 820 ± 96 vs. second half: 817 ± 86 ms; PL first half: 824 ± 114 vs. second half: 847 ± 118 ms; P < 0.05). There was no difference in response accuracy., Conclusions: These findings suggest that dietary NO3 (-) enhances repeated sprint performance and may attenuate the decline in cognitive function (and specifically reaction time) that may occur during prolonged intermittent exercise.

Fatmax and lactate increase above baseline (LIAB) were measured in 11 adolescent girls and 8 adolescent boys during incremental cycling. Fatmax was the exercise intensity at the point of maximal fat oxidation rate (MFO). The LIAB was the exercise intensity coincident with a sustained increase in blood (lactate) above an initial baseline. We defined the minimum important difference (MID) between the exercise intensity at Fatmax and LIAB as +/-8% of both peak VO2 and peak heart rate (HR). Systematic bias was examined via the mean difference between parameters and its uncertainty, with inference based on the disposition of the confidence interval to the MID. Individual-level agreement was the proportion of differences between Fatmax and LIAB falling within the MID. MFO was at 35 (6)% peak VO2 with LIAB at 39 (7)% peak VO2 Systematic bias was -3.8% of peak VO2 and -4.4% of peak HR. The estimated population proportion with between-variable agreement within +/-8% was 0.76 for both % peak VO2 and % peak HR. Within the tolerance limits of the MID, the mean bias is 'almost certainly not' important; similarly, there is good agreement between the two parameters at the individual level. We conclude that Fatmax and lactate increase above baseline coincide in adolescents.

The aim of this study is to investigate the effects of CHO ingestion during high intensity exercise performance lasting approximately 25 min. Twelve endurance trained male cyclists (age 19-41 years; body mass 73.2 +/- 4.2 kg; VO(2)max 66.4 +/- 6.2 ml kg(-1) min(-1)) completed a simulated 16 km time trial (457 +/- 37 kJ) time trial in the lab on three occasions. Once they received a 6% carbohydrate electrolyte solution (CHO) and twice they received the same electrolyte containing placebo drink (PLA). Carbohydrate or placebo drinks were ingested 5 min before the start (4 ml kg(-1)) and at 25, 50, and 75% of completion of the time trial (1.4 ml kg(-1)). The CHO drink was a 6% sucrose-glucose-electrolyte solution. No differences were observed in the time to complete the time trials with either treatment. Time in min:s were 25:30 +/- 1:34 and 25:27 +/- 1:46 for the two placebo trials and 25:38 +/- 1:59 in the CHO trial. Power output during the time trials was also remarkably similar: 300 +/- 37 W, 301 +/- 39 W and 299 +/- 40 W, respectively. Pacing strategies and heart rate were identical in all three trials. From the two placebo trials, a coefficient of variation for this performance task was calculated to be 1.1%. Data from this study provides evidence that carbohydrate ingestion during short high intensity exercise (approximately 30 min, 85-90% VO(2)max) does not improve performance. Furthermore, this study found a very low coefficient of variation (1.1%) for a simulated 16 km time trial.

It is well documented that a single bout of endurance exercise (EE) can improve insulin sensitivity, whereas relatively little is known about the acute effects of resistance exercise (RE) in humans. The objective of this study is to investigate the insulin and glucose responses to an oral glucose tolerance test (OGTT) following a high intensity bout of either EE or RE followed by post-exercise carbohydrate-protein hydrolysate ingestion. Eighteen participants were divided into two groups: a group in which nine participants completed 1 h of EE (cycle ergometry at 75% W (max)) and a RE group in which nine participants completed a RE circuit (3 sets of 10 repetitions). Participants ingested 1.5 l of a carbohydrate (200 g)-protein hydrolysate (50 g) beverage within 1 h of exercise completion. An OGTT was performed 6 h post-exercise. On the control day the endurance and resistance groups performed the above protocol without the prior exercise (CEE or CRE). The control and exercise days were counterbalanced. RE reduced plasma glucose AUC (822 +/- 68 vs. 694 +/- 23 mmol l(-1).120 min; CRE vs. RE, respectively; P < 0.05) but EE did not lead to a change (784 +/- 40 vs. 835 +/- 59 mmol l(-1).120 min; CEE vs. EE, respectively). Plasma insulin AUC remained unchanged compared to the control in both the RE and EE groups. The results suggest that the benefit of RE on glucose tolerance following CHO intake remains for 6 h even when a carbohydrate-protein hydrolysate beverage was ingested within 1 h after exercise, while the well documented benefit of EE was not observed.

The aim of this study was to investigate the reliability of a protocol designed to simulate endurance performance in events of long duration (approximately 5 h) where endogenous carbohydrate stores are low. Seven male subjects were recruited (age 27 +/- 7 years, VO(2max) 66 +/- 5 ml/kg/min, W (max) 367 +/- 42 W). The subjects underwent three trials to determine the reliability of the protocol. For each trial subjects entered the laboratory in the evening to undergo a glycogen-depleting exercise trial lasting approximately 2.5 h. The subjects returned the following morning in a fasted state to undertake a 1-h steady-state ride at 50% W (max) followed by a time trial of approximately 40-min duration. Each trial was separated by 7-14 days. The trials were analysed for reliability of time to completion of the time trial using a coefficient of variation (CV), with 95% confidence intervals (data are mean +/- SD). The times to complete the three trials were 2,546 +/- 529, 2,585 +/- 490 and 2,568 +/- 555 s for trials 1, 2 and 3, respectively. The CV between trials 1 and 2 was 4.5% (95% CI 2.9-10.4%) and between trials 2 and 3, 3.8% (95% CI 2.4-9.9%). There was no difference in oxygen uptake, respiratory exchange ratio, carbohydrate oxidation, fat oxidation, plasma glucose concentration and plasma lactate concentration between the three trials. Therefore we can conclude that prior glycogen depletion does produce a reliable measure of performance with metabolic characteristics similar to ultraendurance exercise.

The purpose of this article was to establish whether previously reported oxygen-to-mass ratios, used to predict flat and hill-climbing cycling performance, extend to similar power-to-mass ratios incorporating other, often quick and convenient measures of power output recorded in the laboratory [maximum aerobic power (W(MAP)), power output at ventilatory threshold (W(VT)) and average power output (W(AVG)) maintained during a 1 h performance test]. A proportional allometric model was used to predict the optimal power-to-mass ratios associated with cycling speeds during flat and hill-climbing cycling. The optimal models predicting flat time-trial cycling speeds were found to be (W(MAP)m(-0.48))(0.54), (W(VT)m(-0.48))(0.46) and (W(AVG)m(-0.34))(0.58) that explained 69.3, 59.1 and 96.3% of the variance in cycling speeds, respectively. Cross-validation results suggest that, in conjunction with body mass, W(MAP) can provide an accurate and independent prediction of time-trial cycling, explaining 94.6% of the variance in cycling speeds with the standard deviation about the regression line, s=0.686 km h(-1). Based on these models, there is evidence to support that previously reported VO2-to-mass ratios associated with flat cycling speed extend to other laboratory-recorded measures of power output (i.e. Wm(-0.32)). However, the power-function exponents (0.54, 0.46 and 0.58) would appear to conflict with the assumption that the cyclists' speeds should be proportional to the cube root (0.33) of power demand/expended, a finding that could be explained by other confounding variables such as bicycle geometry, tractional resistance and/or the presence of a tailwind. The models predicting 6 and 12% hill-climbing cycling speeds were found to be proportional to (W(MAP)m(-0.91))(0.66), revealing a mass exponent, 0.91, that also supports previous research.

The glycaemic and insulinaemic responses to different carbohydrates vary and these have been suggested to affect performance. The purpose of the present study was to determine the effects of pre-exercise ingestion of glucose (GLU), galactose (GAL) and trehalose (TRE) on metabolic responses at rest and during exercise and on subsequent time-trial (TT) performance. Eight well-trained male cyclists completed three exercise trials separated by at least 3 days. At 45 min before the start of exercise subjects consumed 500 ml of a beverage containing 75 g of either glucose, galactose or trehalose. The exercise trials consisted of 20 min of submaximal steady-state exercise (SS) at 65% of maximal power output immediately followed by a [mean (SEM)] 702 (25) kJ TT. Plasma glucose concentration 15 min postprandial was significantly higher in GLU compared to GAL and TRE ( P<0.05). This was accompanied by a more than twofold greater rise in plasma insulin concentration in GLU compared to GAL and TRE (118% and 145%, respectively). During SS exercise four subjects in GLU and one subject in TRE developed a rebound hypoglycaemia (plasma glucose concentration less than 3.5 mmol.l(-1)). No differences were observed in TT performance between the three trials. Pre-exercise ingestion of trehalose and galactose resulted in lower plasma glucose and insulin responses prior to exercise and reduced the prevalence of rebound hypoglycaemia. Despite the attenuated insulin and glucose responses at rest and during exercise following pre-exercise ingestion of galactose and trehalose, there was no difference in TT performance compared with pre-exercise ingestion of glucose.

The development of rebound hypoglycaemia has been reported after pre-exercise carbohydrate (CHO) ingestion in some studies but not in others. Differences in the experimental design and factors such as the exercise intensity are likely to be responsible for the discrepancies between these studies. Exercise intensity might be a crucial factor since it affects both insulinaemia and glucose uptake. Therefore the aim of the present study was to compare the glycaemic and insulinaemic responses to exercise at different intensities after ingestion of a standardized pre-exercise CHO load. Eight moderately trained subjects consumed 75 g of glucose 45 min prior to 20 min of exercise at 40%, 65% or 80% maximal power output. Blood samples were collected before glucose ingestion, at 15 min intervals at rest and 5 min intervals during exercise. During exercise, measurements of heart rate and breath-by-breath analysis of expired gas were performed continuously. The trials were performed at [mean (SEM)] 55 (1), 77 (1) and 90 (1) percentages maximal oxygen uptake. At the onset of exercise, plasma glucose concentration returned to pre-ingestion levels, while the insulin concentration was more than three times higher than at rest [on average 57 (7) compared to 16 (1) microU.ml(-1)]. During exercise, plasma glucose concentrations decreased during the first 5 min of exercise and then stabilized in all trials at concentrations that would not be considered to be hypoglycaemic. There were no significant differences in glucose or insulin concentrations between the three trials during exercise. These data suggest that the glycaemic response to ingestion of 75 g of CHO 45 min pre-exercise is similar during exercise of different intensities.

Studies on the effect of the pre-exercise ingestion of carbohydrate on metabolism and performance have produced conflicting results, perhaps because of differences in the designs of the studies. The purpose of the present study was to examine the effects of ingesting differing amounts of glucose pre-exercise on the glucose and insulin responses during exercise and on time-trial (TT) performance. Nine well-trained male cyclists completed four exercise trials separated by at least 3 days. At 45 min before the start of exercise subjects consumed 500 ml of a beverage containing either 0 g (PLAC), 25 g (LOW), 75 g (MED) or 200 g (HIGH) of glucose. The exercise trials consisted of 20 min of submaximal steady-state exercise (SS) at 65% of maximal power output immediately followed by a [mean (SEM)] 691 (12) kJ TT. Plasma insulin concentrations at the onset of exercise were significantly higher ( P<0.05) in MED and HIGH compared with LOW and PLAC. Plasma glucose concentration fell rapidly ( P<0.05) during SS exercise in all glucose trials, but remained steady in PLAC. No difference in plasma glucose concentration was observed between the glucose trials at any time. Hypoglycaemia (less than 3.5 mmol.l(-1)) was observed in six subjects during SS but only after ingesting glucose pre-exercise. However, there was no difference in TT performance between the four trials. The ingestion of 0, 25, 75 or 200 g of glucose 45 min before a 20 min submaximal exercise bout did not affect subsequent TT performance. In addition, mild rebound hypoglycaemia following pre-exercise glucose ingestion did not negatively affect performance.

The occurrence of rebound hypoglycaemia may depend on the timing of carbohydrate intake. The aim of the present study was to investigate the metabolic and performance responses to the ingestion of carbohydrate at differing times before exercise. Eight subjects [mean (SEM)] [28 (3) years, 74.5 (2.6) kg, maximal oxygen uptake 63.1 (3.1) ml.kg(-1).min(-1)] performed three experiments. They ingested 75 g glucose dissolved in 500 ml water, thereafter resting for either 15, 45 or 75 min (15-Pre, 45-Pre and 75-Pre) before exercising for 20 min at 65% maximal power output followed by a time trial [total work 685 (18) kJ]. There were no differences in performance between conditions [mean powers 268 (10), 269 (7) and 276 (12) W for 15-Pre, 45-Pre and 75-Pre, respectively]. There were significant differences in plasma glucose concentration between 15-Pre [6.6 (0.6) mmol.l(-1); P<0.05] and both 45-Pre [4.5 (0.2) mmol.l(-1)] and 75-Pre [3.7 (0.2) mmol.l(-1)] immediately before exercise. Insulin concentrations immediately before exercise were higher ( P<0.05) during 15-Pre [72.6 (10.4) microU.ml(-1)] than during 45-Pre [50.8 (9.9) microU.ml(-1)], which was higher ( P<0.05) than during 75-Pre [33.9 (5.5) microU.ml(-1)]. These differences disappeared within 10 min of exercise. Two subjects became hypoglycaemic (plasma glucose concentration of less than 3.5 mmol.l(-1)) in the 15-Pre while three and five subjects were transiently hypoglycaemic in the 45-Pre and 75-Pre, respectively. Performance and rating of perceived exertion did not seem to be related to hypoglycaemia. Altering the timing of the ingestion of carbohydrate before exercise resulted in differences in plasma glucose/insulin responses which disappeared within 10 min of exercise and which had no effect on performance. Hypoglycaemia was observed in some subjects during the first 10 min but this did not affect performance.

Information concerning the validity and reliability of commercial on-line gas analysis systems is limited. The aim of this study was to provide a comparison of the validity and reliability of three on-line systems (Oxycon Alpha, Oxycon Pro and Pulmolab EX670) with that of Douglas bags. Two separate studies were conducted. In study 1, the three gas analysis systems were compared with Douglas bags using a metabolic simulator over four increases in ventilation. In study 2, ten subjects were split into equal groups exercising at 100 W or 150 W for 85 min on three separate occasions. Each system was used twice per visit. Study 1 demonstrated that the Oxycon Alpha and Douglas bags produced similar respiratory values over all levels of ventilation. The Oxycon Pro tended to slightly overestimate mean expiratory flow (V(E) ), oxygen uptake ( VO2), carbon dioxide production (VCO2) and respiratory exchange ratio (RER) at the higher ventilations. The Pulmolab produced large overestimations at all ventilations for and RER (up to 26.3% away from expectations), whilst values for, and were slightly underestimated at higher ventilations (up to 7.5% from expectations). The results of study 2 support the findings of study 1, with the Oxycon Pro and Oxycon Alpha producing similar results compared to Douglas bags for, and RER. The coefficients of variation for and measured using Douglas bags, Oxycon Pro and Oxycon Alpha were 3.3-5.1%, 4.7-7.0% and 4.5-6.3%, respectively, whilst that for the Pulmolab was highly variable (26.8-45.8%). The exercise study showed the Oxycon Pro and Oxycon Alpha to be both valid and reliable on-line systems for the measurement of parameters of respiration, at least at workloads up to 150 W.

To investigate the effects of replacing a portion of endurance training by strength training on exercise performance, 14 competitive cyclists were divided into an experimental (E; n = 6) and a control (C; n = 8) group. Both groups received a training program of 9 weeks. The total training volume for both groups was the same [E: 8.8 (1.1) h/week; C: 8.9 (1.7) h/week], but 37% of training for E consisted of explosive-type strength training, whilst C received endurance training only. Simulated time trial performance (TT), short-term performance (STP), maximal workload (Wmax) and gross (GE) and delta efficiency (DE) were measured before, after 4 weeks and at the end of the training program (9 weeks). No significant group-by-training effects for the markers of endurance performance (TT and Wmax) were found after 9 weeks, although after 4 weeks, these markers had only increased (P < 0.05) in E. STP decreased (P < 0.05) in C, whereas no changes were observed in E. For DE, a significant group-by-training interaction (P < 0.05) was found, and for GE the group-by-training interaction was not significant. It is concluded that replacing a portion of endurance training by explosive strength training prevents a decrease in STP without compromising gains in endurance performance of trained cyclists.