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Jorn Trommelen, Milou Beelen, Marjan Mullers, Martin J. Gibala, Luc J.C. van Loon and Naomi M. Cermak

Carbohydrate mouth rinsing during exercise has been suggested to enhance performance of short (45–60 min) bouts of high-intensity (>75% VO2peak) exercise. Recent studies indicate that this performance enhancing effect may be dependent on the prandial state of the athlete. The purpose of this study was to define the impact of a carbohydrate mouth rinse on ~1-hr time trial performance in both the fasted and fed states. Using a double-blind, crossover design, 14 trained male cyclists (27 ± 6 years; 5.0 ± 0.5 W·kg−1) were selected to perform 4 time trials of ~1 hr (1,032 ± 127 kJ) on a cycle ergometer while rinsing their mouths with a 6.4% sucrose solution (SUC) or a noncaloric sweetened placebo (PLA) for 5 s at the start and at every 12.5% of their set amount of work completed. Two trials were performed in an overnight fasted state and two trials were performed 2 h after consuming a standardized breakfast. Performance time did not differ between any of the trials (fasted-PLA: 68.6 ± 7.2; fasted-SUC: 69.6 ± 7.5; fed-PLA: 67.6 ± 6.6; and fed-SUC: 69.0 ± 6.3 min; Prandial State × Mouth Rinse Solution p = .839; main effect prandial state p = .095; main effect mouth rinse solution p = .277). In line, mean power output and heart rate during exercise did not differ between trials. In conclusion, a sucrose mouth rinse does not improve ~1-hr time trial performance in well-trained cyclists when performed in either the fasted or the fed state.

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Jennie A. Gilbert and James E. Misner

This study examined the metabolic response to a 763-kcal mixed meal at rest and during 30 min of exercise at 50% maximal oxygen consumption (VO2max) in 8 aerobically trained (AT), 8 resistance trained (RT), and 8 untrained (UT) subjects. Oxygen consumption (VO,) was measured minute by minute during 30 min of exercise by indirect calorimetry on 2 nonconsecutive days (postabsorptive exercise, PA; and postprandial exercise, PP). Total VO, consumed and total caloric expenditure during the PA and PP conditions were similar for the three groups, indicating that prior food intake did not affect energy expenditure during exercise. Consequently, TEM during exercise did not differ significantly among the groups. Respiratory exchange ratio (R) differed significantly only during the PA condition, with the AT group exhibiting significantly lower R values compared to the RT group, and significantly lower R values compared to the UT group. These data suggest that the consumption of a meal 30 min prior to exercise does not increase TEM during exercise in AT, RT, and UT subjects.

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Krystyna Burkhard-Jagodzinska, Krystyna Nazar, Maria Ladyga, Janina Starczewska-Czapowska and Lech Borkowski

Twelve girls who trained in rowing were examined twice a year for 4 years. Their initial age was 11.7 ± (SD) 0.2 yrs. Control groups consisted of 13 girls age 11.5±0.3 yrs and 18 girls age 14.4±0.3 yrs examined simultaneously with trained girls in the first and last year of the study, respectively. The examination involved basic anthropometry, estimation of sexual maturation (Tanner scale), 2-day food records, measurements of resting metabolic rate, energy expenditure following glucose ingestion (50 g), and determinations of blood glucose and plasma insulin concentrations prior to and 2 hrs after glucose load. Body mass, height, and fat content were slightly greater in trained girls. None of the subjects reported disturbances in menstrual function, and the age of menarche was similar for all. Both trained and untrained girls reported similar daily energy intake closer to the lower limit or slightly below the estimates of energy requirements for adolescents. Resting metabolic rate calculated per kg of total body mass or lean body mass was lower in trained girls, while the thermogenic effect of glucose was greater. Plasma insulin concentrations measured 2 hrs after glucose ingestion were lower in trained girls. The results suggest that in circumpubertal girls, increased physical activity leads to energy conservation at rest in postabsorptive state and a tendency toward enhancement of food-induced thermogenesis.

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Gabriella A.M. Ten Have, Marielle P.K.J. Engelen, Yvette C. Luiking and Nicolaas E.P. Deutz

The small intestine acts as interface and regulator between the gut lumen and the rest of the body and controls the degree and rate of transport of amino acids coming from dietary protein via the portal vein to the liver and the systemic circulation. To measure protein absorption, kinetics multicatheter animal (pig) models in combination with amino acid tracer technology are available. Dietary factors infuence the absorption rates from the lumen to the gut, metabolism of dietary component in the gut, and the release of amino acids to the portal circulation from digested protein. In a balanced-protein meal, the gut dietary amino acid utilization (30–50%) for gut protein synthesis will result in a labile protein pool in the gut that can be benefcial during the postabsorptive state. To enhance gut retention, amount and quality of protein and the presence of carbohydrate are major factors. Besides this the use of a slowly digestible protein or the presence of fber in the meal can increase retention further. During the absorption of low-quality protein meals, fewer amino acids are utilized by the gut, resulting in higher amounts of amino acid release to the portal circulation. Malnutrition or starvation, protein depletion, defciencies of specifc nutrients, or illness such as sepsis all inhibit the growth and change protein turnover of the intestinal mucosa and therefore affect absorption kinetics. Therefore, the kind of protein meal that has the most optimal absorption kinetics (the most benefcial) for gut and for the rest of the body depends on these (patho)physiological circumstances. Despite the absence of different absorption kinetics between protein, peptides, and amino acids, they could be benefcial in specifc circumstances.

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Amy J. Hector and Stuart M. Phillips

protein timing and balanced distribution translates into better retention of LBM in elite athletes. Sleep is critical for recovery and performance of elite athletes, with average durations of sleep lasting ∼8 hr ( Knufinke et al., 2018 ; Staunton et al., 2017 ), and represents a prolonged postabsorptive

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Ana B. Peinado, Nuria Romero-Parra, Miguel A. Rojo-Tirado, Rocío Cupeiro, Javier Butragueño, Eliane A. Castro, Francisco J. Calderón and Pedro J. Benito

time trial and characteristics of the mountain pass. RPE indicates rating of perceived exertion. Participants reported to the testing location in a 3-hour-postabsorptive state. Body and bike mass were measured. Participants were then asked to perform a 30-minute warm-up at an intensity ranging from 60

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Emily Arentson-Lantz, Elfego Galvan, Adam Wacher, Christopher S. Fry and Douglas Paddon-Jones

of falling. Walking bouts were completed within approximately 18–22 min between 10:00 and 11:00 each morning. Vastus lateralis muscle samples (∼200 mg/biopsy) were obtained pre- and post-BR on study Days 4 and 11 using a 5-mm Bergström biopsy needle with subjects in the postabsorptive state. Outcome

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William Abbott, Adam Brett, Emma Cockburn and Tom Clifford

MPS throughout the day. 9 , 10 Such effects might not translate to scenarios whereby exercise is performed in the evening, and there are fewer opportunities to further promote MPS before sleep—typically a 7 to 10 hours postabsorptive period. Indeed, it has been shown that a single dose of 20 to 30 g

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Chris Brogden, Kelly Marrin, Richard Page and Matt Greig

attended the ambient temperature controlled laboratory in a 3-hour postabsorptive state, following 24 hours of abstinence from alcohol, caffeine, and vigorous exercise. Prior to the completion of each testing sessions, participants undertook a 10-minute standardized warm-up protocol. Participants were also

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Petter Fagerberg

adjusted to account for EEE and to restore EA to the set level. Authors did not mention how EEE was measured and EA levels needs to be interpreted with caution • Energy balance: 45 • Energy deficiency: 30 Changes in body composition were not reported • Postabsorptive rates of MPS were 27% lower in energy