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Purpose We previously observed increased energy intake (EI) at the meal before planned afternoon exercise, but the proximity of the meal to exercise might have reduced the scale of the pre-exercise anticipatory eating. Therefore, this study examined EI in the 24 h before fasted morning exercise. Methods Fourteen males, experienced with gym-based aerobic exercise (age 25 ± 5 years, BMI 23.8 ± 2.5 kg/m2), completed counterbalanced exercise (EX) and resting (REST) trials. On day 1, subjects were told the following morning’s activity (EX/REST), before eating ad-libitum laboratory-based breakfast and lunch meals and a home-based afternoon/evening food pack. The following morning, subjects completed 30-min cycling and 30-min running (EX; 3274 ± 278 kJ) or 60-min supine rest (REST; 311 ± 34 kJ) fasted. Appetite was measured periodically, and EI quantified. Results Afternoon/evening EI (EX 7371 ± 2176 kJ; REST 6437 ± 2070 kJ; P = 0.017) and total 24-h EI (EX 14,055 ± 3672 kJ; REST 12,718 ± 3379 kJ; P = 0.011) were greater during EX, with no difference between trials at breakfast (P = 0.761) or lunch (P = 0.071). Relative EI (EI minus energy expended through EX/REST) was lower in EX (EX 10,781 ± 3539 kJ; REST 12,407 ± 3385 kJ; P = 0.004). Conclusion This study suggests planned fasted aerobic exercise increases EI during the preceding afternoon/evening, precipitating a ~ 10% increase in EI in the preceding 24-h. However, this increase did not fully compensate for energy expended during exercise; meaning exercise induced an acute negative energy balance.

This study tested the hypothesis that exposure to chlorine-sterilised pool water would impair oral nitrate reduction (ONR). ONR was assessed in elite swimmers before and after morning and afternoon pool-based training. Nonswimmers were only assessed in the morning. ONR was similar in swimmers and nonswimmers (P = 1.000) and unchanged before and after morning and afternoon training (P ≥ 0.341). Therefore, exposure to chlorinated pool water does not interfere with ONR. Novelty Exposure to chlorine-sterilised pool water does not impair oral nitrate reduction in elite swimmers.

Eight well-trained cyclists ingested 68 g·h−1 of a carbohydrate-electrolyte solution with sodium alginate and pectin (CHO-ALG) or a taste and carbohydrate type-matched carbohydrate-electrolyte solution (CHO) during 120 min of cycling at 55% maximal power followed by an ∼20 min time trial. Oxygen uptake, carbon dioxide production, blood glucose concentration, substrate oxidation, gastrointestinal symptoms, and time trial performance (CHO-ALG: 1219 ± 84 s, CHO: 1267 ± 102 s; P = 0.185) were not different between trials. Novelty Inclusion of sodium alginate and pectin in a carbohydrate drink does not influence blood glucose, substrate oxidation, gastrointestinal comfort, or performance in cyclists.

Effects of exercise on subsequent energy intake are well documented, but whether preexercise energy intake is affected by future planned exercise is unknown. This study investigated the effect of planned late-afternoon exercise on appetite and energy intake before (breakfast and lunch) and after (evening meal/snacks) exercise.Twenty healthy, active participants (10 male; age, 23 ± 5 yr; body mass index 23.7 ± 3.2 kg·m; V˙O2peak, 44.1 ± 5.4 mL·kg··min) completed randomized, counterbalanced exercise (EX) and resting (REST) trials. After trial notification, participants were provided ad libitum breakfast (0800 h) and lunch (1200 h) in the laboratory, before completing 1-h exercise (30-min cycling, 30-min running) at 75%-80% maximal HR (EX, 2661 ± 783 kJ) or 1-h supine rest (REST, 310 ± 58 kJ) 3 h after lunch. Participants were provided a food pack (pasta meal/snacks) for consumption after exercise (outside laboratory). Appetite was measured regularly, and meal and 24-h energy intake were quantified.Ad libitum energy intake was greater during EX at lunch (EX, 3450 ± 1049 kJ; REST, 3103 ± 927 kJ; P = 0.004), but similar between trials at breakfast (EX, 2656 ± 1291 kJ; REST, 2484 ± 1156 kJ; P = 0.648) and dinner (EX, 6249 ± 2216 kJ; REST, 6240 ± 2585 kJ; P = 0.784). Total 24-h energy intake was similar between trials (P = 0.388), meaning that relative energy intake (24-h energy intake minus EX/REST energy expenditure) was reduced during EX (EX, 9694 ± 3313 kJ; REST, 11,517 ± 4023 kJ; P = 0.004).Energy intake seems to be increased in anticipation of, rather than in response to, aerobic exercise, but the increase was insufficient to compensate for energy expended during exercise, meaning that aerobic exercise reduced energy balance relative to rest.

The practice of rapid weight loss (RWL) in mixed martial arts (MMA) is an increasing concern but data remain scarce. The aim of this study was to investigate the prevalence, magnitude, methods, and influencers of RWL in professional and amateur MMA athletes. MMA athletes (N = 314; 287 men and 27 women) across nine weight categories (strawweight to heavyweight), completed a validated questionnaire adapted for this sport. Sex-specific data were analyzed, and subgroup comparisons were made between athletes competing at professional and amateur levels. Most athletes purposefully reduced body weight for competition (men: 97.2%; women: 100%). The magnitude of RWL in 1 week prior to weigh-in was significantly greater for professional athletes compared with those competing at amateur level (men: 5.9% vs. 4.2%; women: 5.0% vs. 2.1% of body weight; p p always” or “sometimes” used water loading (72.9%), restricting fluid intake (71.3%), and sweat suits (55.4%) for RWL. Coaches were cited as the primary source of influence on RWL practices (men: 29.3%; women: 48.1%). There is a high reported prevalence of RWL in MMA, at professional and amateur levels. Our findings, constituting the largest inquiry to date, call for urgent action from MMA organizations to safeguard the health and well-being of athletes competing in this sport.

In many situations, meals are planned (i.e. what and how much) before they are eaten, but how exercise influences this planning is unknown. Therefore, this study investigated whether anticipation of an exercise session alters food intake planned for post-exercise. Forty (16 male) regular exercisers (mean ± SD; age 23.3 ± 5.6 y, BMI 22.7 ± 3.3 kg/m2, body fat 25.6 ± 7.6%) completed the study. Subjects arrived ≥3 h post-prandial and were given two hypothetical scenarios for the following day: 1) morning rest (REST), or 2) morning rest with the addition of 1 h of hard aerobic exercise at 10:00–11:00 (EXERCISE). For each scenario subjects had to plan their lunch, to consume at 12:00, by serving themselves cheesy tomato pasta and chocolate buttons. Scenarios were randomised and separated by 5 min and foods were not consumed. EXERCISE increased total energy served by 24% (EXERCISE 3308 ± 1217 kJ; REST 2663 ± 924 kJ; P

Bin Naharudin, MN, Yusof, A, Shaw, H, Stockton, M, Clayton, DJ, and James, LJ. Breakfast omission reduces subsequent resistance exercise performance. J Strength Cond Res 33(7): 1766-1772, 2019-Although much research has examined the influence of morning carbohydrate intake (i.e., breakfast) on endurance performance, little is known about its effects on performance in resistance-type exercise. Sixteen resistance-trained men (age 23 ± 4 years, body mass 77.56 ± 7.13 kg, and height 1.75 ± 0.04 m) who regularly (≥3 day/wk) consumed breakfast completed this study. After assessment of 10 repetition maximum (10RM) and familiarization process, subjects completed 2 randomized trials. After an overnight fast, subjects consumed either a typical breakfast meal (containing 1.5 g of carbohydrate/kg; breakfast consumption [BC]) or a water-only breakfast (breakfast omission [BO]). Two hours later, subjects performed 4 sets to failure of back squat and bench press at 90% of their 10RM. Sensations of hunger, fullness, desire to eat, and prospective food consumption were collected before, as well as immediately, 1 hour and 2 hours after BC/BO using 100-mm visual analogue scales. Total repetitions completed were lower during BO for both back squat (BO: 58 ± 11 repetitions; BC: 68 ± 14 repetitions; effect size [ES] = 0.98; p < 0.001) and bench press (BO: 38 ± 5 repetitions; BC: 40 ± 5 repetitions; ES = 1.06; p < 0.001). Fullness was greater, whereas hunger, desire to eat, and prospective food consumption were lower after a meal for BC compared with BO (p < 0.001). The results of this study demonstrate that omission of a pre-exercise breakfast might impair resistance exercise performance in habitual breakfast consumers. Therefore, consumption of a high-carbohydrate meal before resistance exercise might be a prudent strategy to help maximize performance.

Objectives Ingested ketogenic agents offer the potential to enhance endurance performance via the provision of an alternative exogenous, metabolically efficient, glycogen-sparing fuel (i.e. ketone bodies). This study aimed to assess the impact of combined carbohydrate and 1,3-butanediol (CHO-BD) supplementation on endurance performance, blood beta-hydroxybutyrate (βHB) concentration and glycolytic activity, in comparison to carbohydrate supplementation alone (CHO). Design Eleven male runners (age 38 ± 12 years, mass 67.3 ± 6.5 kg, height 174.5 ± 5.0 cm, V ˙ O 2 p e a k 64.2 ± 5.0 ml⋅kg−1⋅min−1) performed two experimental trials in a randomised crossover design. Methods Each trial consisted of 60 min of submaximal running, followed by a 5 km running time-trial (TT), and was performed following the ingestion of an energy matched ∼650 ml drink (CHO-BD or CHO). Results There was no difference in TT completion time between the trials (CHO: 1265 ± 93, CHO-BD: 1261 ± 96 s; p = 0.723). However, blood βHB concentration in the CHO-BD trial was at least double that of the CHO trial at all time points following supplementation (p Conclusions An energy matched CHO-BD supplementation drink raised βHB concentration and acutely lowered blood lactate concentration, without enhancing 5 km TT running performance.

Purpose Whilst there is evidence to suggest that hypohydration caused by physical work in the heat increases renal injury, whether this is the case during exercise in temperate conditions remains unknown. This study investigated the effect of manipulating hydration status during high-intensity intermittent running on biomarkers of renal injury. Methods After familiarisation, 14 males (age: 33 ± 7 years; V̇O2peak: 57.1 ± 8.6 ml/kg/min; mean ± SD) completed 2 trials in a randomised cross-over design, each involving 6, 15 min blocks of shuttle running (modified Loughborough Intermittent Shuttle Test protocol) in temperate conditions (22.3 ± 1.0 °C; 47.9 ± 12.9% relative humidity). During exercise, subjects consumed either a volume of water equal to 90% of sweat losses (EU) or 75 mL water (HYP). Body mass, blood and urine samples were taken pre-exercise (baseline/pre), 30 min post-exercise (post) and 24 h post-baseline (24 h). Results Post-exercise, body mass loss, serum osmolality and urine osmolality were greater in HYP than EU (P ≤ 0.024). Osmolality-corrected urinary kidney injury molecule-1 (uKIM-1) concentrations were increased post-exercise (P ≤ 0.048), with greater concentrations in HYP than EU (HYP: 2.76 [1.72–4.65] ng/mOsm; EU: 1.94 [1.1–2.54] ng/mOsm; P = 0.003; median [interquartile range]). Osmolality-corrected urinary neutrophil gelatinase-associated lipocalin (uNGAL) concentrations were increased post-exercise (P P = 0.073). Conclusion These results suggest that hypohydration produced by high-intensity intermittent running increases renal injury, compared to when euhydration is maintained, and that the site of this increased renal injury is at the proximal tubules.

Hypohydration increases physiological strain and reduces physical and technical soccer performance, but there are limited data on how fluid balance responses change between different types of sessions in professional players. This study investigated sweat and fluid/carbohydrate intake responses in elite male professional soccer players training at low and high intensities in cool and hot environments. Fluid/sodium (Na+) losses and ad-libitum carbohydrate/fluid intake of fourteen elite male soccer players were measured on four occasions: cool (wet bulb globe temperature (WBGT): 15 &plusmn, 7 &deg, C, 66 &plusmn, 6% relative humidity (RH)) low intensity (rating of perceived exertion (RPE) 2&ndash, 4, m&middot, min&minus, 1 40&ndash, 46) (CL), cool high intensity (RPE 6&ndash, 8, m&middot, 1 82&ndash, 86) (CH), hot (29 &plusmn, 1 &deg, C, 52 &plusmn, 7% RH) low intensity (HL), hot high intensity (HH). Exercise involved 65 &plusmn, 5 min of soccer-specific training. Before and after exercise, players were weighed in minimal clothing. During training, players had ad libitum access to carbohydrate beverages and water. Sweat [Na+] (mmol&middot, L&minus, 1), which was measured by absorbent patches positioned on the thigh, was no different between conditions, CL: 35 &plusmn, 9, CH: 38 &plusmn, 8, HL: 34 &plusmn, 70.17, HH: 38 &plusmn, 8 (p = 0.475). Exercise intensity and environmental condition significantly influenced sweat rates (L&middot, h&minus, 1), CL: 0.55 &plusmn, 0.20, CH: 0.98 &plusmn, 0.21, HL: 0.81 &plusmn, 0.17, HH: 1.43 &plusmn, 0.23 (p =0.001), and percentage dehydration (p &lt, 0.001). Fluid intake was significantly associated with sweat rate (p = 0.019), with no players experiencing hypohydration &gt, 2% of pre-exercise body mass. Carbohydrate intake varied between players (range 0&ndash, 38 g&middot, 1), with no difference between conditions. These descriptive data gathered on elite professional players highlight the variation in the hydration status, sweat rate, sweat Na+ losses, and carbohydrate intake in response to training in cool and hot environments and at low and high exercise intensities.

Objectives: Short periods of excessive consumption of indulgent high-fat foods are common in Western society, but the effect this has on bone is unknown. The aim of this pilot study was to explore how a 7-d hyperenergetic, high-fat diet affects candidate biomarkers of bone metabolism.\ud \ud Methods: The study included 12 healthy men with a mean age of 24 y (SD = 4 y) and body mass index (BMI) of 24.1 kg/m2 (SD = 1.5). The men consumed a 7-d hyperenergetic, high-fat diet (HE-HFD; 20.9 [SD = 0.8] MJ; 65% total energy as fat) and a control (CON) diet (10.9 [SD = 2] MJ; 36% total energy as fat), in randomized, crossover order, with each trial separated by 3 wk. Markers of bone formation (P1NP) and bone resorption (CTx) were measured at baseline and after 1, 3, and 7 d of each diet. Bone metabolic responses were analyzed using two-factor repeated-measures analysis of variance and subsequent pairwise comparisons.\ud \ud Results: There was a main effect of time (P < 0.05), but no trial (P = 0.270) or time- × -trial interaction (P = 0.693) effects for plasma concentrations of CTx. Mean CTx concentrations did not differ between trials (CON: 0.97 ng/mL [SD = 0.39]; HE-HFD: 1.03 ng/mL [SD = 0.22]; P = 0.225). There was a main effect of trial (P < 0.01), but no time (P = 0.138) or trial- × -interaction (P = 0.179) effects for plasma concentrations of P1NP. Mean P1NP concentrations were lower during the HE-HFD (61.79 ng/mL [SD = 26.54]) than during the CON diet (77.89 ng/mL [SD = 28.71]; P < 0.01).\ud \ud Conclusions: A 7-d hyperenergetic, high-fat diet reduces a marker of bone formation but does not affect a marker of bone resorption. This pilot study suggested that short periods of excessive energy and fat consumption may detrimentally affect bone health.

This study investigated metabolic, endocrine, appetite and mood responses to a maximal eating occasion in fourteen men (mean: age 28 (sd5) years, body mass 77·2 (sd6·6) kg and BMI 24·2 (sd2·2) kg/m2) who completed two trials in a randomised crossover design. On each occasion, participants ate a homogenous mixed-macronutrient meal (pizza). On one occasion, they ate until ‘comfortably full’ (ad libitum) and on the other, until they ‘could not eat another bite’ (maximal). Mean energy intake was double in the maximal (13 024 (95 % CI 10 964, 15 084) kJ; 3113 (95 % CI 2620, 3605) kcal) compared with thead libitumtrial (6627 (95 % CI 5708, 7547) kJ; 1584 (95 % CI 1364, 1804) kcal). Serum insulin incremental AUC (iAUC) increased approximately 1·5-fold in the maximal compared withad libitumtrial (mean:ad libitum43·8 (95 % CI 28·3, 59·3) nmol/l × 240 min and maximal 67·7 (95 % CI 47·0, 88·5) nmol/l × 240 min,P< 0·01), but glucose iAUC did not differ between trials (ad libitum94·3 (95 % CI 30·3, 158·2) mmol/l × 240 min and maximal 126·5 (95 % CI 76·9, 176·0) mmol/l × 240 min,P= 0·19). TAG iAUC was approximately 1·5-fold greater in the maximalv.ad libitumtrial (ad libitum98·6 (95 % CI 69·9, 127·2) mmol/l × 240 min and maximal 146·4 (95 % CI 88·6, 204·1) mmol/l × 240 min,P< 0·01). Total glucagon-like peptide-1, glucose-dependent insulinotropic peptide and peptide tyrosine–tyrosine iAUC were greater in the maximal compared withad libitumtrial (P< 0·05). Total ghrelin concentrations decreased to a similar extent, but AUC was slightly lower in the maximalv.ad libitumtrial (P= 0·02). There were marked differences on appetite and mood between trials, most notably maximal eating caused a prolonged increase in lethargy. Healthy men have the capacity to eat twice the energy content required to achieve comfortable fullness at a single meal. Postprandial glycaemia is well regulated following initial overeating, with elevated postprandial insulinaemia probably contributing.

Exercise intensity affects many potential postprandial responses, but there is limited information on the influence of exercise modality. Therefore, the aim of this study was to investigate if the nature of exercise at two different intensities would affect gastric emptying rate (GER), appetite and metabolic responses following ingestion of a semi-solid meal. Twelve healthy men completed, in a random order, four 60-min cycles at 60% VO2peak (MOD), 40% VO2peak (LOW) and in a continuous (CON) or intermittent (INT) manner. INT consisted of 20 &times, 1-min exercise bouts with 2-min rest breaks. INT and CON were matched for total work output at each intensity. GER of the post-exercise meal was measured for 2 h using the 13C-breath method. Blood glucose, substrate utilisation and appetite ratings were measured at regular intervals throughout all trials and 24-h energy intake (EI) post-trials was assessed. GER-Delta over Baseline (DOB) was lower (p &lt, 0.05) on MOD-INT vs. MOD-CON from 30&ndash, 120 min post-meal. Blood glucose was higher mid-exercise (p &lt, 0.05) on MOD-INT vs. MOD-CON. Although post-exercise LOW-CON was significantly higher than LOW-INT (p &lt, 0.05), blood glucose was also higher 30-min post-meal ingestion on both CON trials compared to INT (p &lt, 0.001). No interaction effect was observed for perceived appetite responses 2 h after meal ingestion (all p &gt, 0.05). 24-h post-trial EI was similar between LOW-CON vs. LOW-INT (p &gt, 0.05), although MOD-INT vs. MOD-CON 3500 &plusmn, 1419 vs. 2556 &plusmn, 989 kCal: p &lt, 0.001 was elevated. In summary, MOD-INT exercise delays GER without stimulating perceived appetite in the 2 h period after meal ingestion, although EI was greater in the 24-h post-trial.

This study investigated whether supplementation with nitrate-rich beetroot juice (BR) can improve high-intensity intermittent running performance in trained males in normoxia and different doses of normobaric hypoxia. Eight endurance-trained males (, 62 ± 6 ml·kg−1·min−1) completed repeated 90 s intervals at 110% of peak treadmill velocity, from an initial step incremental test, interspersed by 60 s of passive recovery until exhaustion (Tlim). Participants completed the first three experimental trials during days 3, 5, and 7 of BR or nitrate-depleted beetroot juice (PLA) supplementation and completed the remaining experimental visits on the alternative supplement following at least 7 days of washout. The fraction of inspired oxygen during visits 1–3 was either 0.209, 0.182, or 0.157, equivalent to an altitude of 0, 1,200, and 2,400 m, respectively, and this order was replicated on visits 4–6. Arterial oxygen saturation declined dose dependently as fraction of inspired oxygen was lowered (p p lim between PLA and BR at 0 m (445 [324, 508] and 410 [368, 548] s); 1,200 m (341 [270, 390] and 332 [314, 356] s); or 2,400 m (233 [177, 373] and 251 [221, 323] s) (median and [interquartile range]; p > .05). The findings from this study suggest that short-term BR supplementation does not improve high-intensity intermittent running performance in endurance-trained males in normoxia or at doses of normobaric hypoxia that correspond to altitudes at which athletes typically train while on altitude training camps.

PURPOSE: To examine the effect on short duration, high intensity cycling time trial performance when a semi-solid breakfast containing carbohydrate or a taste and texture matched placebo is ingested 90 minutes pre-exercise compared to a water control. METHODS: Thirteen well trained cyclists (25 ± 8 years, 71.1 ± 5.9 kg, 1.76 ± 0.04 m, 383 ± 46 Wmax, VO2peak 4.42 ± 0.53 L·min-1) performed three experimental trials examining breakfast ingestion 90 minutes before a 10 minute steady state cycle (60% Wmax) and a ~20 minute time trial (to complete a workload target of 376 ± 36 kJ). Subjects consumed either water (WAT), a semi-solid carbohydrate breakfast (2 g carbohydrate·kg-1 body mass; CHO) or a taste and texture matched placebo (PLA). Blood lactate and glucose concentrations were measured periodically throughout the rest and exercise periods. RESULTS: The time trial was completed quicker in CHO (1120 ± 69 s; P=0.006) and PLA (1112 ± 50 s; P=0.030) compared to WAT (1146 ± 74 s). Ingestion of carbohydrate caused an increase in blood glucose concentration throughout the rest period in CHO (peak at 30 minutes rest: 7.37 ± 1.10 mmol·l-1; P

Objectives This study investigated the influence of a moderate caffeine dose on endurance cycle performance and thermoregulation during prolonged exercise in high ambient temperature. Design Double-blind cross-over study. Methods Eight healthy, recreationally active males (mean ± SD; age: 22 ± 1 years; body mass: 71.1 ± 8.5 kg; VO2peak: 55.9 ± 5.8 mL kg−1 min−1; Wmax: 318 ± 37 W) completed one VO2peak test, one familiarisation trial and two experimental trials. After an overnight fast, participants ingested a placebo or a 6 mg kg−1 caffeine dose 60 min before exercise. The exercise protocol consisted of 60 min of cycle exercise at 55% Wmax, followed by a 30 min performance task (total kJ produced) in 30 °C and 50% RH. Results Performance was enhanced (Cohen’s d effect size = 0.22) in the caffeine trial (363.8 ± 47.6 kJ) compared with placebo (353.0 ± 49.0 kJ; p = 0.004). Caffeine did not influence core (p = 0.188) or skin temperature (p = 0.577) during exercise. Circulating prolactin (p = 0.572), cortisol (p = 0.842) and the estimated rates of fat (p = 0.722) and carbohydrate oxidation (p = 0.454) were also similar between trial conditions. Caffeine attenuated perceived exertion during the initial 60 min of exercise (p = 0.033), with no difference in thermal stress across trials (p = 0.911). Conclusions Supplementation with 6 mg kg−1 caffeine improved endurance cycle performance in a warm environment, without differentially influencing thermoregulation during prolonged exercise at a fixed work-rate versus placebo. Therefore, moderate caffeine doses which typically enhance performance in temperate environmental conditions also appear to benefit endurance performance in the heat.

Background: Few studies have investigated the effect of hydration status on appetite for food in healthy adults. Prior work suggests hydration status does not alter appetite or energy intake, with mixed findings regarding appetite hormone secretion. However, an extensive investigation into both the psychological and physiological appetitive responses to hydration status has never been conducted. Objective: To investigate the effect of hydration status on multiple facets of appetite.Design: After 3 days pre-trial standardization, a range of appetite tasks were conducted when hypohydrated (HYPO) and euhydrated (EUHY) in 16 healthy participants (8 men). Hydration status was manipulated via dehydration in a heat tent for 60 min and subsequent fluid restriction (HYPO) or replacement (EUHY). The next day, a food reward computer task was completed followed by an ad libitum pasta meal. Pre- and post-prandial visual analogue scales assessing hunger, fullness, and flavour desires (sweet, salty, savoury and fatty) were additionally completed. Blood samples were taken the previous day before the hydration interventions in a euhydrated state, and in the fasted and post-prandial state during HYPO and EUHY.Results: HYPO induced -1.9 ± 1.2% body mass change, compared to -0.2 ± 0.6%, with accompanying changes in markers of hypohydration which were not seen during EUHY. A higher desire for foods was associated with a higher water content but the association was weaker in EUHY compared to HYPO, (β= -0.33 mm/g of food water content, p < 0.001) in the food reward task. Visual analogue scales showed similar hunger and fullness between interventions, but during HYPO there was consistently higher thirst (average range in difference 27–32 mm across all time points) and lower fasted desire for salt (−23, 95% CI −10, −35 mm). Ad libitum energy intake (HYPO 1953 ± 742 kJ, EUHY 2027 ± 926 kJ; p = 0.542) and post-prandial ghrelin concentrations (HYPO 180 ± 65 pg mL−1, EUHY 188 ± 71 pg mL−1; p = 0.736) were similar by hydration status.Conclusions: An acute manipulation to hydration status altered desire for salt and foods of differing water contents, but did not influence energy intake at an ad libitum pasta meal. Further research should investigate whether these appetites would alter food choice.

Background: Chronic hot water immersion (HWI) confers health benefits, including a reduction in fasting blood glucose concentration. Here we investigate acute glycaemic control immediately after HWI. Methods: Ten participants (age: 25 ± 6 years, body mass: 84 ± 14 kg, height 1.85 ± 0.09 m) were immersed in water (39oC) to the neck (HWI) or sat at room temperature (CON) for 60 min. One hour afterwards they underwent an oral glucose tolerance test (OGTT), with blood collected before and after HWI/CON and during the 2 h OGTT. Results: Glucose incremental area under the curve (iAUC) during the OGTT was higher for HWI (HWI 233 ± 88, CON 156 ± 79 mmol·L-1·2h, P = 0.02). Insulin iAUC did not differ between conditions (HWI 4309 ± 3660, CON 3893 ± 3031 mU·L-1·2h, P=0.32). Core temperature increased to 38.6 ± 0.2°C during HWI, but was similar between trials during the OGTT (HWI 37.0 ± 0.2, CON 36.9 ± 0.4°C, P=0.34). Directly following HWI, plasma average adrenaline and growth hormone concentrations increased 2.7 and 10.7-fold, respectively (P < 0.001). Plasma glucagon like peptide-1, peptide YY and acylated ghrelin concentrations were not different between trials during the OGTT (P > 0.11). Conclusions: HWI increased postprandial glucose concentration to an OGTT, which was accompanied by acute elevations of stress hormones following HWI. The altered glycaemic control appears to be unrelated to changes in gut hormones during the OGTT.

Context The mechanisms responsible for dietary fat-induced insulin resistance of skeletal muscle and its microvasculature are only partially understood. Objective To determine the impact of high-fat overfeeding on postprandial glucose fluxes, muscle insulin signaling, and muscle microvascular endothelial nitric oxide synthase (eNOS) content and activation. Design Fifteen non-obese volunteers consumed a high-fat (64%) high-energy (+47%) diet for 7 days. Experiments were performed before and after the diet. Stable isotope tracers were used to determine glucose fluxes in response to carbohydrate plus protein ingestion. Muscle insulin signaling was determined as well as the content and activation state of muscle microvascular eNOS. Results High-fat overfeeding impaired postprandial glycemic control as demonstrated by higher concentrations of glucose (+11%; P = 0.004) and insulin (+19%; P = 0.035). Carbohydrate plus protein ingestion suppressed endogenous glucose production to a similar extent before and after the diet. Conversely, high-fat overfeeding reduced whole-body glucose clearance (–16%; P = 0.021) and peripheral insulin sensitivity (–26%; P = 0.006). This occurred despite only minor alterations in skeletal muscle insulin signaling. High-fat overfeeding reduced eNOS content in terminal arterioles (P = 0.017) and abolished the increase in eNOS Ser1177 phosphorylation that was seen after carbohydrate plus protein ingestion. Conclusion High-fat overfeeding impaired whole-body glycemic control due to reduced glucose clearance, not elevated endogenous glucose production. The finding that high-fat overfeeding abolished insulin-mediated eNOS Ser1177 phosphorylation in the terminal arterioles suggests that impairments in the vasodilatory capacity of the skeletal muscle microvasculature may contribute to early dietary fat-induced impairments in glycemic control.

Knowledge of hydration status may contribute to hypohydration-induced exercise performance decrements; therefore, this study compared blinded and unblinded hypohydration on cycling performance. Fourteen trained, nonheat-acclimated cyclists (age: 25 ± 5 yr; V̇o2peak: 63.3 ± 4.7 ml·kg−1·min−1; cycling experience: 6 ± 3 yr) were pair matched to blinded (B) or unblinded (UB) groups. After familiarization, subjects completed euhydrated (B-EUH; UB-EUH) and hypohydrated (B-HYP; UB-HYP) trials in the heat (31°C); 120-min cycling preload (50% Wpeak) and a time trial (~15 min). During the preload of all trials, 0.2 ml water·kg body mass−1 was ingested every 10 min, with additional water provided during EUH trials to match sweat losses. To blind the B group, a nasogastric tube was inserted in both trials and used to provide water in B-EUH. The preload induced similar ( P = 0.895) changes in body mass between groups (B-EUH: −0.6 ± 0.5%; B-HYP: −3.0 ± 0.5%; UB-EUH: −0.5 ± 0.3%; UB-HYP −3.0 ± 0.3%). All variables responded similarly between B and UB groups ( P ≥ 0.558), except thirst ( P = 0.004). Changes typical of hypohydration (increased heart rate, rating of perceived exertion, gastrointestinal temperature, serum osmolality and thirst, and decreased plasma volume; P ≤ 0.017) were apparent in HYP by 120 min. Time trial performance was similar between groups ( P = 0.710) and slower ( P ≤ 0.013) with HYP for B (B-EUH: 903 ± 89 s; B-HYP: 1,008 ± 121 s; −11.4%) and UB (UB-EUH: 874 ± 108 s; UB-HYP: 967 ± 170 s; −10.1%). Hypohydration of ~3% body mass impairs time trial performance in the heat, regardless of knowledge of hydration status. NEW & NOTEWORTHY This study demonstrates, for the first time, that knowledge of hydration status does not exacerbate the negative performance consequences of hypohydration when hypohydration is equivalent to ~3% body mass. This is pivotal for the interpretation of the many previous studies that have not blinded subjects to their hydration status and suggests that these previous studies are not likely to be confounded by the overtness of the methods used to induce hypohydration.

Background: Intermittent severe energy restriction (SER) can induce substantial weight loss, but the appetite regulatory responses to SER are unknown and may dictate long-term dietary adherence.\ud \ud Objective: We determined the effect of 24-h SER on appetite regulation, metabolism, and energy intake.\ud \ud Design: Eighteen lean men and women completed two 3-d trials in randomized, counterbalanced order. On day 1 subjects consumed standardized diets containing 100% (mean 6 SD: 9.3 6 1.3 MJ; energy balance) or 25% [2.3 6 0.3 MJ; energy restriction (ER)] of energy requirements. On day 2, a standardized breakfast was consumed, with plasma concentrations of acylated ghrelin, glucagon-like peptide 1, insulin, glucose, and nonesterified fatty acids determined for 4 h. Ad libitum energy intake was assessed at lunch and dinner with subjective appetite and resting metabolism assessed throughout. On day 3, ad libitum energy intake was assessed at breakfast and by weighed food records.\ud \ud Results: Energy intake was 7% greater on day 2 (P

Purpose - Protein consumption after resistance exercise potentiates muscle protein synthesis, but its effects on subsequent appetite in this context are unknown. This study examined appetite and energy intake following consumption of protein- and carbohydrate-containing drinks after resistance exercise.\ud \ud Methods - After familiarisation, 15 resistance training males (age 21 ± 1 years, body mass 78.0 ± 11.9 kg, stature 1.78 ± 0.07 m) completed two randomised, double-blind trials, consisting of lower-body resistance exercise, followed by consumption of a whey protein (PRO 23.9 ± 3.6 g protein) or dextrose (CHO 26.5 ± 3.8 g carbohydrate) drink in the 5 min post-exercise. An ad libitum meal was served 60 min later, with subjective appetite measured throughout. Drinks were flavoured and matched for energy content and volume. The PRO drink provided 0.3 g/kg body mass protein.\ud \ud Results - Ad libitum energy intake (PRO 3742 ± 994 kJ; CHO 4172 ± 1132 kJ; P = 0.007) and mean eating rate (PRO 339 ± 102 kJ/min; CHO 405 ± 154 kJ/min; P = 0.009) were lower during PRO. The change in eating rate was associated with the change in energy intake (R = 0.661, P = 0.007). No interaction effects were observed for subjective measures of appetite. The PRO drink was perceived as creamier and thicker, and less pleasant, sweet and refreshing (P < 0.05).\ud \ud Conclusion - These results suggest whey protein consumption after resistance exercise reduces subsequent energy intake, and this might be partially mediated by a reduced eating rate. Whilst this reduced energy intake is unlikely to impair hypertrophy, it may be of value in supporting an energy deficit for weight loss.

Single bouts of land-based exercise (for example, walking, running, cycling) do not typically alter post-exercise energy intake on the day of exercise. However, anecdotal and preliminary empirical evidence suggests that swimming may increase appetite and energy intake. This study compared the acute effects of swimming on appetite, energy intake, and food preference and reward, versus exertion-matched cycling and a resting control. Thirty-two men (n = 17; mean ± SD age 24 ± 2 years, body mass index [BMI] 25.0 ± 2.6 kg/m2) and women (n = 15; age 22 ± 3 years, BMI 22.8 ± 2.3 kg/m2) completed three experimental trials (swimming, cycling, control) in a randomised, crossover design. The exercise trials involved 60-min of ‘hard’ exercise (self-selected rating of perceived exertion: 15) performed 90-min after a standardised breakfast. Food preference and reward were assessed via the Leeds Food Preference Questionnaire 15-min after exercise, whilst ad libitum energy intake was determined 30-min after exercise. The control trial involved identical procedures except no exercise was performed. Compared with control (3259 ± 1265 kJ), swimming increased ad libitum energy intake (3857 ± 1611 kJ; ES = 0.47, 95% CI of the mean difference between trials 185, 1010 kJ, P = 0.005); the magnitude of increase was smaller after cycling (3652 ± 1619 kJ; ES = 0.31, 95% CI -21, 805 kJ, P = 0.062). Ad libitum energy intake was similar between swimming and cycling (ES = 0.16, 95% CI -207, 618 kJ, P = 0.324). This effect was consistent across sexes and unrelated to food preference and reward which were similar after swimming and cycling compared with control. This study has identified an orexigenic effect of swimming. Further research is needed to identify the responsible mechanism(s), including the relevance of water immersion and water temperature per se.

Research shows that expected satiety is highly correlated with ideal portion size, however this correspondence has not been explored when a food is presented in an ‘unusual’ (incongruous) meal context. This study's aim was to explore whether expected satiety influences portion selection to the same extent in both congruous and incongruous meal contexts. Forty participants completed two trials (one at breakfast and one at lunch) on separate days in a randomised counterbalanced order. They completed measures of expected satiety and ideal portion size for four typical breakfast foods and four typical lunch foods, using a bespoke computer program. Our results showed a significant difference between expected satiety and ideal portion size for lunch foods presented at breakfast time (an incongruous meal context; t(39) = 2.95, p = 0.02). There was no significant difference between expected satiety and ideal portion size in the other incongruous meal context (breakfast foods at lunch; t(39) = 2.10, p = 0.17) or in congruous meal contexts (breakfast foods at breakfast time, lunch foods at lunch time; both t(39) ≤ −0.15, p > 0.999). These results suggest that expected satiety does not have as strong an influence on portion selection when food is presented in an unusual context. Furthermore, in such contexts, smaller portions were selected 1) to stave off hunger until the next meal and 2) as ideal portions compared to in more usual meal contexts. Research is warranted to explore this finding further to understand its implications for weight management.

Intermittent energy restriction (IER) involves short periods of severe energy restriction interspersed with periods of adequate energy intake, and can induce weight loss. Insulin sensitivity is impaired by short-term, complete energy restriction, but the effects of IER are not well known. In randomised order, fourteen lean men (age: 25 (sd 4) years; BMI: 24 (sd 2) kg/m2; body fat: 17 (4) %) consumed 24-h diets providing 100 % (10 441 (sd 812) kJ; energy balance (EB)) or 25 % (2622 (sd 204) kJ; energy restriction (ER)) of estimated energy requirements, followed by an oral glucose tolerance test (OGTT; 75 g of glucose drink) after fasting overnight. Plasma/serum glucose, insulin, NEFA, glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic peptide (GIP) and fibroblast growth factor 21 (FGF21) were assessed before and after (0 h) each 24-h dietary intervention, and throughout the 2-h OGTT. Homoeostatic model assessment of insulin resistance (HOMA2-IR) assessed the fasted response and incremental AUC (iAUC) or total AUC (tAUC) were calculated during the OGTT. At 0 h, HOMA2-IR was 23 % lower after ER compared with EB (PPPPP=0·161), GIP (P=0·473) and FGF21 (P=0·497) tAUC were similar between trials. These results demonstrate that severe energy restriction acutely impairs postprandial glycaemic control in lean men, despite reducing HOMA2-IR. Chronic intervention studies are required to elucidate the long-term effects of IER on indices of insulin sensitivity, particularly in the absence of weight loss.

There is a paucity of data examining the effect of cutlery size on the microstructure of within-meal eating behaviour or food intake. Therefore, the present studies examined how manipulation of spoon size influenced these eating behaviour measures in lean young men. In study one, subjects ate a semi-solid porridge breakfast ad libitum, until satiation. In study two, subjects ate a standardised amount of porridge, with mean bite size and mean eating rate covertly measured by observation through a one-way mirror. Both studies involved subjects completing a familiarisation visit and two experimental visits, where they ate with a teaspoon (SMALL) or dessert spoon (LARGE), in randomised order. Subjective appetite measures (hunger, fullness, desire to eat and satisfaction) were made before and after meals. In study one, subjects ate 8 % less food when they ate with the SMALL spoon (SMALL 532 (SD 189) g; LARGE 575 (SD 227) g; P=0·006). In study two, mean bite size (SMALL 10·5 (SD 1·3) g; LARGE 13·7 (SD 2·6) g; PSD 25) g/min; LARGE 108 (SD 29) g/min; Pad libitum food intake, possibly via a cascade of effects on within-meal eating microstructure. A small spoon might be a practical strategy for decreasing bite size and eating rate, likely increasing oral processing, and subsequently decreasing food intake, at least in lean young men.

Whey protein is a commonly ingested nutritional supplement amongst athletes and regular exercisers, however, its role in post-exercise rehydration remains unclear. Eight healthy male and female participants completed two experimental trials involving the ingestion of 35 g of whey protein (WP) or maltodextrin (MD) at the onset of a rehydration period, followed by ingestion of water to a volume equivalent to 150% of the amount of body mass lost during exercise in the heat. The gastric emptying rates of the solutions were measured using 13C breath tests. Recovery was monitored for a further 3 h by the collection of blood and urine samples. The time taken to empty half of the initial solution (T1/2) was different between the trials (WP = 65.5 &plusmn, 11.4 min, MD = 56.7 &plusmn, 6.3 min, p = 0.05), however, there was no difference in cumulative urine volume throughout the recovery period (WP = 1306 &plusmn, 306 mL, MD = 1428 &plusmn, 443 mL, p = 0.314). Participants returned to net negative fluid balance 2 h after the recovery period with MD and 3 h with WP. The results of this study suggest that whey protein empties from the stomach at a slower rate than MD, however, this does not seem to exert any positive or negative effects on the maintenance of fluid balance in the post-exercise period.

This study examined the effects of sodium chloride and potassium chloride supplementation during 48-h severe energy restriction on exercise capacity in the heat. Nine males completed three 48-h trials: adequate energy intake (100 % requirement), adequate electrolyte intake (CON); restricted energy intake (33 % requirement), adequate electrolyte intake (ER-E); and restricted energy intake (33 % requirement), restricted electrolyte intake (ER-P). At 48 h, cycling exercise capacity at 60 % $$ \dot{V} $$ O2 peak was determined in the heat (35.2 °C; 61.5 % relative humidity). Body mass loss during the 48 h was greater during ER-P [2.16 (0.36) kg] than ER-E [1.43 (0.47) kg; P

This study investigated the effects of hydration status and fluid availability on appetite and energy intake. Sixteen males completed four 24 h trials, visiting the laboratory overnight fasted on two consecutive days. Standardised foods were provided during the 24 h and on day two an ad-libitum semi-solid porridge breakfast was provided. Water intake during the 24 h (0 or 40 mL⋅kg(-1)) and fluid provision during the ad-libitum breakfast were manipulated so subjects were euhydrated with (EU-F) and without fluid (EU-NF) available at breakfast; and hypohydrated with (HYPO-F) and without fluid (HYPO-NF) available at breakfast. Blood samples (0 and 24 h), urine samples (0-24 h) and subjective responses (0, 24 and 24.5 h) were collected. HYPO trials decreased body mass by ~1.8%. Serum and urine osmolality increased and plasma volume decreased during HYPO trials (P 0.001). Total urine output was greater during EU than HYPO trials (P 0.001). Ad-libitum energy intake was not different between trials: 2658 (938) kJ (EU-F), 2353 (643) kJ (EU-NF), 2295 (529) kJ (HYPO-F), 2414 (954) kJ (HYPO-NF), (P = 0.131). Fluid intake was ~200 mL greater during HYPO-F than EU-F (P 0.01). There was an interaction effect for thirst (P 0.001), but not hunger or fullness. These results demonstrate that mild hypohydration produced by inadequate fluid intake and fluid availability during eating does not influence ad-libitum energy intake of a semi-solid breakfast, at least in healthy young males.

Angiotensin converting enzyme (ACE) and bradykinin receptor B2 (B2R) genetic variation may affect thirst because of effects on angiotensin II production and bradykinin activity, respectively. To examine this, 45 healthy Caucasian men completed 60 min of cycle exercise at 62% ± 5% peak oxygen uptake in a room heated to 30.5 ± 0.3 °C with ad libitum fluid intake. Blood samples were collected pre-, mid-, and immediately post-cycle. Fluid intake, body mass loss (BML), sweat loss (determined via changes in body mass and fluid intake), and thirst sensation were recorded. All participants were genotyped for the ACE insert fragment (I) and the B2R insert sequence (P). Participants were homozygous for the wild-type allele (WW or MM), heterozygous (WI or MP) or homozygous for the insert (II or PP). No differences between genotype groups were found in mean (±SD) voluntary fluid intake (WW: 613 ± 388, WI: 753 ± 385, II: 862 ± 421 mL, p = 0.31; MM: 599 ± 322, MP: 745 ± 374, PP: 870 ± 459 mL, p = 0.20), percentage BML or any other fluid balance variables for both the ACE and B2R genes, respectively. Mean thirst perception in the B2R PP group, however, was higher (p < 0.05) than both MM and MP at 30, 45, and 60 min. In conclusion, the results of this study suggest that voluntary fluid intake and fluid balance in healthy men performing 60 min of moderate-intensity exercise in the heat are not predominantly influenced by ACE or B2R genetic variation.

This study examined the effect of electrolyte addition to drinks ingested after severe fluid and energy restriction (FER). Twelve subjects (6 male and 6 female) completed 3 trials consisting of 24-hour FER (energy intake: 21 kJ·kg body mass; water intake: 5 ml·kg body mass), followed by a 2-hour rehydration period and a 4-hour monitoring period. During rehydration, subjects ingested a volume of drink equal to 125% of the body mass lost during FER in 6 aliquots, once every 20 minutes. Drinks were a sugar-free lemon squash (P) or the P drink with the addition of 50 mmol·L sodium chloride (Na) or 30 mmol·L potassium chloride (K). Total void urine samples were given before and after FER and every hour during rehydration and monitoring. Over all trials, FER produced a 2.1% reduction in body mass and negative sodium (-67 mmol), potassium (-48 mmol), and chloride (-84 mmol) balances. Urine output after drinking was 1627 (540) ml (P), 1391 (388) ml (K), and 1150 (438) ml (Na), with a greater postdrinking urine output during P than Na (p ≤ 0.05). Ingestion of drink Na resulted in a more positive sodium balance compared with P or K (p < 0.001), whereas ingestion of drink K resulted in a more positive potassium balance compared with P or Na (p < 0.001). These results demonstrate that after 24-hour FER, ingestion of a high sodium drink results in an increased sodium balance that augments greater drink retention compared with a low electrolyte placebo drink.

This study assessed the effect of carbohydrate intake on self-selected soccer-specific running performance. Sixteen male soccer players (age 23 ± 4 years; body mass 76.9 ± 7.2 kg; predicted VO2max = 54.2 ± 2.9 mL∙kg−1∙min−1; soccer experience 13 ± 4 years) completed a progressive multistage fitness test, familiarisation trial and two experimental trials, involving a modified version of the Loughborough Intermittent Shuttle Test (LIST) to simulate a soccer match in a fed state. Subjects completed six 15 min blocks (two halves of 45 min) of intermittent shuttle running, with a 15-min half-time. Blocks 3 and 6, allowed self-selection of running speeds and sprint times, were assessed throughout. Subjects consumed 250 mL of either a 12% carbohydrate solution (CHO) or a non-caloric taste matched placebo (PLA) before and at half-time of the LIST. Sprint times were not different between trials (CHO 2.71 ± 0.15 s, PLA 2.70 ± 0.14 s; p = 0.202). Total distance covered in self-selected blocks (block 3: CHO 2.07 ± 0.06 km; PLA 2.09 ± 0.08 km; block 6: CHO 2.04 ± 0.09 km; PLA 2.06 ± 0.08 km; p = 0.122) was not different between trials. There was no difference between trials for distance covered (p ≥ 0.297) or mean speed (p ≥ 0.172) for jogging or cruising. Blood glucose concentration was greater (p < 0.001) at the end of half-time during the CHO trial. In conclusion, consumption of 250 mL of 12% CHO solution before and at half-time of a simulated soccer match does not affect self-selected running or sprint performance in a fed state.

The addition of whey protein to a carbohydrate-electrolyte drink has been shown to enhance post-exercise rehydration when a volume below that recommended for full fluid balance restoration is provided. We investigated if this held true when volumes sufficient to restore fluid balance were consumed and if differences might be explained by changes in plasma albumin content. Sixteen participants lost ~1.9% of their pre-exercise body mass by cycling in the heat and rehydrated with 150% of body mass lost with either a 60 g · L(-1) carbohydrate drink (CHO) or a 60 g · L(-1) carbohydrate, 20 g · L(-1) whey protein isolate drink (CHO-P). Urine and blood samples were collected pre-exercise, post-exercise, post-rehydration and every hour for 4 h post-rehydration. There was no difference between trials for total urine production (CHO 1057 ± 319 mL; CHO-P 970 ± 334 mL; P = 0.209), drink retention (CHO 51 ± 12%; CHO-P 55 ± 15%; P = 0.195) or net fluid balance (CHO -393 ± 272 mL; CHO-P -307 ± 331 mL; P = 0.284). Plasma albumin content relative to pre-exercise was increased from 2 to 4 h during CHO-P only. These results demonstrate that the addition of whey protein isolate to a carbohydrate-electrolyte drink neither enhances nor inhibits rehydration. Therefore, where post-exercise protein ingestion might benefit recovery, this can be consumed without effecting rehydration.

The purpose of this study was to examine the gastric emptying and rehydration effects of hypotonic and hypertonic glucose-electrolyte drinks after exercise-induced dehydration. Eight healthy males lost ~1.8% body mass by intermittent cycling and rehydrated (150% of body mass loss) with a hypotonic 2% (2% trial) or a hypertonic 10% (10% trial) glucose-electrolyte drink over 60 min. Blood and urine samples were taken at preexercise, postexercise, and 60, 120, 180, and 240 min postexercise. Gastric and test drink volume were determined 15, 30, 45, 60, 90, and 120 min postexercise. At the end of the gastric sampling period 0.3% (2% trial) and 42.1% (10% trial; p < .001) of the drinks remained in the stomach. Plasma volume was lower (p < .01) and serum osmolality was greater (p < .001) at 60 and 120 min during the 10% trial. At 240 min, 52% (2% trial) and 64% (10% trial; p < .001) of the drinks were retained. Net fluid balance was greater from 120 min during the 10% trial (p < .001). When net fluid balance was corrected for the volume of fluid in the stomach, it was greater at 60 and 120 min during the 2% trial (p < .001). These results suggest that the reduced urine output following ingestion of a hypertonic rehydration drink might be mediated by a slower rate of gastric emptying, but the slow gastric emptying of such solutions makes rehydration efficiency difficult to determine in the hours immediately after drinking, compromising the calculation of net fluid balance.

Weight categorized athletes use a variety of techniques to induce rapid weight loss (RWL) in the days leading up to weigh in. This study examined the fluid and electrolyte balance responses to 24-hr fluid restriction (FR), energy restriction (ER) and fluid and energy restriction (F+ER) compared with a control trial (C), which are commonly used techniques to induce RWL in weight category sports. Twelve subjects (six male, six female) received adequate energy and water (C) intake, adequate energy and restricted water (~10% of C; FR) intake, restricted energy (~25% of C) and adequate water (ER) intake or restricted energy (~25% of C) and restricted (~10% of C) water intake (F+ER) in a randomized counterbalanced order. Subjects visited the laboratory at 0 hr, 12 hr, and 24 hr for blood and urine sample collection. Total body mass loss was 0.33% (C), 1.88% (FR), 1.97% (ER), and 2.44% (F+ER). Plasma volume was reduced at 24 hr during FR, ER, and F+ER, while serum osmolality was increased at 24 hr for FR and F+ER and was greater at 24 hr for FR compared with all other trials. Negative balances of sodium, potassium, and chloride developed during ER and F+ER but not during C and FR. These results demonstrate that 24 hr fluid and/or energy restriction significantly reduces body mass and plasma volume, but has a disparate effect on serum osmolality, resulting in hypertonic hypohydration during FR and isotonic hypohydration during ER. These findings might be explained by the difference in electrolyte balance between the trials.

The general scientific consensus is that starting exercise with hypohydration >2% body mass impairs endurance performance/capacity, but most previous studies might be confounded by a lack of subject blinding. This study examined the effect of hypohydration in a single blind manner using combined oral and intragastric rehydration to manipulate hydration status. After familiarization, seven active males (mean ± SD: age 25 ± 2 years, height 1.79 ± 0.07, body mass 78.6 ± 6.2, V O 2peak 48 ± 7 mL·kg·min −1 ) completed two randomized trials at 34°C. Trials involved an intermittent exercise preload (8 × 15 min exercise/5 min rest), followed by a 15‐min all‐out performance test on a cycle ergometer. During the preload, water was ingested orally every 10 min (0.2 mL·kg body mass −1 ). Additional water was infused into the stomach via a gastric feeding tube to replace sweat loss (EU) or induce hypohydration of ~2.5% body mass (HYP). Blood samples were drawn and thirst sensation rated before, during, and after exercise. Body mass loss during the preload was greater (2.4 ± 0.2% vs. 0.1 ± 0.1%; P 0.001), while work completed during the performance test was lower (152 ± 24 kJ vs. 165 ± 22 kJ; P 0.05) during HYP. At the end of the preload, heart rate, RPE, serum osmolality, and thirst were greater and plasma volume lower during HYP ( P 0.05). These results provide novel data demonstrating that exercise performance in the heat is impaired by hypohydration, even when subjects are blinded to the intervention.

Objectives The aim of this study was to examine the influence of octopamine supplementation on endurance performance and exercise metabolism. Design Double-blind cross-over study. Methods Ten healthy, recreationally active men (Mean ± SD; age: 24 ± 2 years; body mass: 78.4 ± 8.7 kg; VO2peak: 50.5 ± 6.8 mL kg−1 min−1) completed one VO2peak test, one familiarisation trial and two experimental trials. After an overnight fast, participants ingested either a placebo or 150 mg of octopamine 60 min prior to exercise. Trials consisted of 30 min of cycle exercise at 55% peak power output, followed by a 30 min performance task whereby participants completed as much work (kJ) as possible. Results Performance was similar between the experimental trials (placebo: 352.8 ± 39 kJ; octopamine: 350.9 ± 38.3 kJ; Cohen’s d effect size = 0.05; p = 0.380). Substrate oxidation and circulating concentrations of free fatty acids, prolactin and cortisol were similar between trial conditions (all p > 0.05). There were also no differences across trials for heart rate or perceived exertion during exercise (both p > 0.05). Conclusions Acute supplementation with a low dose of octopamine did not influence endurance cycle performance, substrate oxidation or circulating hormonal concentrations, which could be due to the low serum octopamine concentrations observed. Future studies should investigate the influence of larger doses of octopamine in recreationally active and well-trained individuals during prolonged exercise in temperate and high ambient conditions.

The aim of the current study was to investigate the influence of mouth rinsing carbohydrate at increasing concentrations on ~1 hr cycle time trial performance. Eleven male cyclists completed three experimental trials, following an overnight fast. Cyclists performed a ~1 hr time trial on a cycle ergometer, while rinsing their mouth for 5 s with either a 7% maltodextrin solution (CHO), 14% CHO or a taste-matched placebo (PLA) after every 12.5% of the set amount of work. Heart rate was recorded every 12.5% of the time trial, while RPE and GI comfort were determined every 25% of the time trial. The mouth rinse protocol influenced the time to complete the time trial (p < .001), with cyclists completing the time trial faster during 7% CHO (57.3 ± 4.5 min; p = .004) and 14% CHO (57.4 ± 4.1 min; p = .007), compared with PLA (59.5 ± 4.9 min). There was no difference between the two carbohydrate trials (p = .737). There was a main effect of time (Pp = .107 and p = .849, respectively). Scores for GI comfort ranged from 0–2 during trials, indicating very little GI discomfort during exercise. In conclusion, mouth rinsing and expectorating a 7% maltodextrin solution, for 5 s routinely during exercise was associated with improved cycle time trial performance approximately 1 h in duration. Increasing the carbohydrate concentration of the rinsed solution from 7% to 14% resulted in no further performance improvement.

Obese individuals exhibit a diminished muscle protein synthesis response to nutrient stimulation when compared with their lean counterparts. However, the effect of obesity on exercise-stimulated muscle protein synthesis remains unknown. Nine lean (23.5 ± 0.6 kg/m2 ) and 8 obese (33.6 ± 1.2 kg/m2 ) physically active young adults participated in a study that determined muscle protein synthesis and intracellular signaling at rest and following an acute bout of resistance exercise. Mixed muscle protein synthesis was determined by combining stable isotope tracer ([13 C6 ]phenylalanine) infusion with serial biopsies of the vastus lateralis. A unilateral leg resistance exercise model was adopted so that resting and postexercise measurements of muscle protein synthesis could be obtained simultaneously. Obesity was associated with higher basal levels of serum insulin (P

This study investigated the acute circulating gut hormone, appetite and gastric emptying rate responses to a semi-solid meal following exercise at different intensities. Twelve men completed three trials in a randomised-crossover design, consisting of continuous cycling at 70% V˙O2Peak (HIGH), 40% V˙O2Peak (LOW) or rest (CONTROL). Baseline samples were collected after an overnight fast before undertaking the 60 min exercise or rest period, followed by 30 min rest before consumption of a standardised semi-solid meal (~242 kcal). During the 2 h postprandial period, gastric emptying rate of the meal was examined using the 13C-breath test method, appetite was measured using visual analogue scales, and serum concentrations of acylated ghrelin, pancreatic polypeptide, peptide YY, glucagon-like peptide-1, insulin, glucose, triglycerides, total cholesterol and non-esterified fatty acids were assessed. Subjective appetite response was not different between trials (p &gt, 0.05). Half emptying time of the meal was 89 &plusmn, 13, 82 &plusmn, 8 and 94 &plusmn, 31 min on CONTROL, LOW and HIGH, respectively (p = 0.247). In healthy un-trained adult males, responses to exercise at intensities of 70% and 40% V˙O2Peak did not differ to a non-exercise control for measurements of subsequent gastric emptying, circulating gut hormone response or appetite. These results suggest that exercise intensity has little effect on post-exercise appetite response to a semi-solid meal.

Although chronic fish oil intervention had been shown to have a positive impact on vascular reactivity, very little is known about their acute effects during the postprandial phase. Our aim was to examine the impact of a fish oil-enriched test meal on postprandial vascular reactivity in healthy younger ( v. older ( ≥ 50 years) men. Vascular reactivity was measured at baseline (0 h), 2 and 4 h after the meal by laser Doppler iontophoresis and blood samples taken at 0 and 4 h for the measurement of plasma lipids, total nitrite, glucose and insulin. Acetylcholine- (ACh, endothelial-dependent vasodilator) and sodium nitroprusside (SNP, endothelial-independent vasodilator)-induced reactivities were greater at 4 h than at baseline or 2 h in the younger men (P P = 0·006) and SNP (P = 0·05) at 4 h in the younger compared with the older males. Postprandial NEFA concentrations were also greater at 4 h in the younger compared with the older men (P = 0·005), with no differences observed for any of the other analytes. Multiple regression analysis revealed age to be the most significant predictor of both ACh and SNP induced reactivity 4 h after the meal. In conclusion, the ingestion of a meal enriched in fish oil fatty acids was shown to improve postprandial vascular reactivity at 4 h in our younger men, with little benefit evident in our older men.

Background/Objectives: Long-term success of weight loss diets might depend on how the appetite regulatory system responds to energy restriction (ER). This study determined the effect of 24 h severe ER on subjective and hormonal appetite regulation, subsequent ad libitum energy intake and metabolism. \ud Subjects/Methods: In randomised order, eight overweight or obese males consumed a 24 h diet containing either 100% (12105 (1174 kJ; energy balance; EB) or 25% (3039 (295) kJ; ER) of estimated daily energy requirements (EER). An individualised standard breakfast containing 25% of EER (3216 (341) kJ) was consumed the following morning and resting energy expenditure, substrate utilisation and plasma concentrations of acylated ghrelin, glucagon-like peptide-1 (GLP-17–36), glucose-dependant insulinotropic peptide (GIP1–42), glucose, insulin and non-esterified fatty acid (NEFA) were determined for 4 h after breakfast. Ad libitum energy intake was assessed in the laboratory on day 2 and via food records on day 3. Subjective appetite was assessed throughout. \ud Results: Energy intake was not different between trials for day 2 (EB: 14946 (1272) kJ; ER: 15251 (2114) kJ; P=0.623), day 3 (EB: 10580 (2457) kJ; 10812 (4357) kJ; P=0.832) or day 2 and 3 combined (P=0.693). Subjective appetite was increased during ER on day 1 (P0.381). Acylated ghrelin, GLP-17–36 and insulin were not different between trials (P>0.104). Post-breakfast area under the curve (AUC) for NEFA (P

AB Purpose: Acute doses of Sinemet(R) (l-DOPA combined with carbidopa) previously failed to influence prolonged exercise performance in a temperate environment, but it is not known whether acute doses of l-DOPA timed to reach maximum plasma concentrations (Cmax) during exercise will improve prolonged cycling performance in warm conditions (30.2[degrees]C +/- 0.2[degrees]C, 50% +/- 1%). Methods: Ten physically active men (age, 26 +/- 4 yr; height, 1.76 +/- 0.08 m; body mass, 76.3 +/- 10.6 kg; V[spacing dot above]O2peak, 57 +/- 8 mL[middle dot]kg-1[middle dot]min-1) were recruited for this study. Participants cycled for 1 h at 60% V[spacing dot above]O2peak followed by a 30-min exercise test, during which they were instructed to complete as much work as possible. Heart rate, skin and core temperatures, as well as RPE and thermal stress were recorded throughout the exercise, and blood samples were collected at rest, at 15-min intervals during the first hour of exercise, and at the end of the exercise test. Finger tapping tests at the beginning and end of the exercise were conducted to examine fine motor control. Results: There was no significant difference in the work done on the placebo (314 +/- 43 kJ) and l-DOPA trials (326 +/- 48 kJ, P = 0.276). Prolactin concentrations were increased at the end of the exercise in all trials (P < 0.001), but this response was attenuated at the end of the exercise for the l-DOPA trial (11.4 +/- 5.5 ng[middle dot]mL-1) and placebo trials (20.8 +/- 3.3 ng[middle dot]mL-1, P = 0.003). No differences between trials were found for any other measure. Conclusions: The results suggest that increasing central catecholamine availability inhibits the normal prolactin response to exercise in the heat but does not alter performance, thermoregulation, or sympathetic outflow

Breakfast omission induces compensatory eating behaviour at lunch, but often reduces daily energy intake. This study investigated the effect of breakfast omission on within-day subjective appetite, energy expenditure, substrate utilisation, and appetite hormone profiles, in response to standardised feeding and exercise.Eight male, habitual breakfast eaters completed two randomised trials. Subjects arrived overnight fasted (0 h), and either consumed (BC) or omitted (BO) a standardized breakfast (mean standard deviation [SD]) (3085 [217] kJ). Lunch (4162 [510] kJ) and dinner (4914 [345] kJ) were provided at 4.5 and 10 h, respectively and subjects performed 60 min fixed-intensity cycling (50% VO2 peak) at 8 h. Blood samples were collected at 0, 4.5, 6, and 8 h, with expired air and subjective appetite sensations (hunger, fullness, desire to eat (DTE), and prospective food consumption [PFC]) collected throughout. Heart rate and perceived exertion were measured during exercise.Hunger, DTE and PFC were greater and fullness lower during BO (P0.05) between breakfast and lunch, with no differences after lunch (P0.193). Resting energy expenditure was greater at 2.5 h during BC (P0.05) with no other differences between trials (P0.156). Active glucogon-like peptide-1 (GLP-17-36) was greater (P0.05) and acylated ghrelin tended to be greater (P = 0.078) at 4.5 h during BC. Heart rate was greater on BO (P0.05) during exercise.The results of this laboratory-controlled study suggest that the effects of breakfast omission are transient and do not extend beyond lunch, even when the negative energy balance created by breakfast omission is sustained via standardised feeding and exercise.

The aim of this study was to evaluate the effects of skimmed milk as a recovery drink following moderate–vigorous cycling exercise on subsequent appetite and energy intake in healthy, female recreational exercisers. Utilising a randomised cross-over design, nine female recreational exercisers (19.7 ± 1.3 years) completed a V̇O2peak test followed by two main exercise trials. The main trials were conducted following a standardised breakfast. Following 30 min of moderate-vigorous exercise (65% V̇O2peak), either 600 mL of skimmed milk or 600 mL of orange drink (475 mL orange juice from concentrate, 125 mL water), which were isoenergetic (0.88 MJ), were ingested, followed 60 min later with an ad libitum pasta meal. Absolute energy intake was reduced 25.2% ± 16.6% after consuming milk compared to the orange drink (2.39 ± 0.70 vs. 3.20 ± 0.84 MJ, respectively, p = 0.001). Relative energy intake (in relation to the energy content of the recovery drinks and energy expenditure) was significantly lower after milk consumption compared to the orange drink (1.49 ± 0.72 vs. 2.33 ± 0.90 MJ, respectively, p = 0.005). There were no differences in AUC (× 1 h) subjective appetite parameters (hunger, fullness and desire to eat) between trials. The consumption of skimmed milk following 30 min of moderate-vigorous cycling exercise reduces subsequent energy intake in female recreational exercisers.

Purpose: Consuming 375-500 ml of water 30 min before a meal has been shown to reduce energy intake in older, but not younger adults. This study investigated the effects of ingesting a water preload immediately pre-meal (

Carbohydrate and protein ingestion post-exercise are known to facilitate muscle glycogen resynthesis and protein synthesis, respectively, but the effects of post-exercise nutrient intake on subsequent appetite are unknown. This study aimed to investigate whether protein induced satiety that has been reported at rest was still evident when pre-loads were consumed in a post-exercise context. Using a randomized, double blind, crossover design, 12 unrestrained healthy males completed 30 min of continuous cycling exercise at ~60% VO2peak, followed by five, 3 min intervals at ~85% VO2peak. Ten min post-exercise, subjects consumed 500 ml of either a low energy placebo (15 kJ) (PLA); a 6% whey protein isolate drink (528 kJ) (PRO); or a 6% sucrose drink (528 kJ) (CHO). Sixty min after drink ingestion, a homogenous ad-libitum pasta lunch was provided and energy intake at this lunch was quantified. Subjective appetite ratings were measured at various stages of the protocol. Energy consumed at the ad-libitum lunch was lower after PRO (5831 ± 960 kJ) than PLA (6406 ± 492 kJ) (P0.315). Considering the post-exercise drink, total energy intake was not different between trials (P=0.383). There were no differences between trials for any of the subjective appetite ratings. The results demonstrate that where post-exercise liquid protein ingestion may enhance the adaptive response of skeletal muscle, and this may be possible without affecting gross energy intake relative to consuming a low energy drink.

The present study investigated the relationship between the milk protein content of a rehydration solution and fluid balance after exercise-induced dehydration. On three occasions, eight healthy males were dehydrated to an identical degree of body mass loss (BML, approximately 1·8 %) by intermittent cycling in the heat, rehydrating with 150 % of their BML over 1 h with either a 60 g/l carbohydrate solution (C), a 40 g/l carbohydrate, 20 g/l milk protein solution (CP20) or a 20 g/l carbohydrate, 40 g/l milk protein solution (CP40). Urine samples were collected pre-exercise, post-exercise, post-rehydration and for a further 4 h. Subjects produced less urine after ingesting the CP20 or CP40 drink compared with the C drink (Psd 12) %) and CP40 (64 (sd 6) %) drinks had been retained compared with the C drink (46 (sd 9) %) (Psd 154) ml) compared with both trials CP20 ( − 181 (sd 280) ml) and CP40 ( − 107 (sd 126) ml) (PP

This study investigated the effects of hypohydration by fluid restriction on voluntary and evoked indices of neuromuscular performance at a functional joint angle. Measures of static volitional peak force (2–3–s maximal muscle actions) and evoked peak twitch force, electromechanical delay, and rate of force development were obtained from the knee extensors (30° knee flexion) of 10 males (age, 24 (4) years; height, 1.76 (0.10) m; body mass, 78.7 (9.13) kg (mean (SD))) prior to and immediately following 24 h of (i) euhydration (EU) and (ii) hypohydration (HYP). Neuromuscular performance was also assessed in response to a fatiguing task (3 × 30-s maximal static knee extensions) following each condition. Repeated-measures ANOVAs showed that HYP was associated with a significant 2.1% loss in body mass (p < 0.001) and a 7.8% reduction in volitional peak force (p < 0.05). Following fatigue, data indicated statistically similar levels of impairment to volitional peak force (11.6%, p < 0.01) and rate of force development (21.0%, p < 0.01) between conditions (EU; HYP). No changes to any other indices of performance were observed. The substantive hypohydration-induced deficits to muscle strength at this functional joint angle might convey a decreased performance capability and should be considered by the hypohydrated athlete. Whilst hypohydration did not affect fatigue-related performance of the knee extensors, the additive changes associated with lower baseline levels of strength performance (7.8%) and fatigue (11.6%) coupled with slower rate of muscle force production (from 0–100 ms) following fatigue may present significant challenges to the maintenance of dynamic knee joint stability, particularly at this vulnerable joint position.

Chronic fish oil intervention had been shown to have a positive impact on endothelial function. Although high-fat meals have often been associated with a loss of postprandial vascular reactivity, studies examining the effects of fish oil fatty acids on vascular function in the postprandial phase are limited. The aim of the present study was to examine the impact of the addition of fish oil fatty acids to a standard test meal on postprandial vascular reactivity. A total of 25 men received in a random order either a placebo oil meal (40 g of mixed fat; fatty acid profile representative of the U.K. diet) or a fish oil meal (31 g of mixed fat and 9 g of fish oil) on two occasions. Vascular reactivity was measured at baseline (0 h) and 4 h after the meal by laser Doppler iontophoresis, and blood samples were taken for the measurement of plasma lipids, total nitrite, glucose and insulin. eNOS (endothelial NO synthase) and NADPH oxidase gene expression were determined in endothelial cells after incubation with TRLs (triacylglycerol-rich lipoproteins) isolated from the plasma samples taken at 4 h. Compared with baseline, sodium nitroprusside (an endothelium-independent vasodilator)-induced reactivity (P=0.024) and plasma nitrite levels (P=0.001) were increased after the fish oil meal. In endothelial cells, postprandial TRLs isolated after the fish oil meal increased eNOS and decreased NADPH oxidase gene expression compared with TRLs isolated following the placebo oil meal (P≤0.03). In conclusion, meal fatty acids appear to be an important determinant of vascular reactivity, with fish oils significantly improving postprandial endothelium-independent vasodilation.