The blood acid base and gastrointestinal response to three different forms of sodium citrate encapsulation.

Enterically coated (ENT) or delayed-release (DEL) capsules may lessen gastrointestinal symptoms (GIS) following acute sodium citrate (SC) ingestion, although the effects on blood acid-base balance are undetermined. Fourteen active males ingested 0.4 g.kg-1 body mass (BM) SC, within gelatine (GEL), DEL and ENT capsules or 0.07 g.kg-1 BM sodium chloride control (CON). Blood acid-base balance and GIS were measured for 4 h. Ingestion form had no significant effect on total GIS experienced (GEL: 2 ± 7; DEL: 1 ± 8; ENT: 1 ± 4 AU). Most (7/14) participants experienced zero symptoms throughout. Peak GIS typically emerged ≤100 min post-ingestion, with a similar time to reach peak GIS between ingestion form (GEL: 36 ± 70; DEL: 13 ± 28; ENT: 15 ± 33 AU). Blood [HCO3-] was significantly higher with ENT versus GEL (ENT: 29.0 ± 0.8; GEL: 28.5 ± 1.1 mmol.L-1, P = 0.037). Acute ingestion of a reduced SC dose elicited minimal GIS, producing significant changes in blood [HCO3-] from rest, irrespective of ingestion form (GEL: 6.0 ± 0.9; DEL: 5.1 ± 1.0; ENT: 6.2 ± 0.8 mmol.L-1). The necessity of individualized ingestion strategies is also challenged, with sustained increases in blood [HCO3-] of ≥4 mmol.L-1 for up to 153 min highlighted. If commencing exercise at peak alkalosis augments subsequent performance above starting at a standardized time point where HCO3- is still elevated remains unclear.

Extracellular buffer choice influences acid-base responses and gastrointestinal symptoms.

To compare the bicarbonate kinetics and gastrointestinal (GI) symptom responses between an equal dose of sodium bicarbonate and sodium citrate using delayed-release capsules. Thirteen active males (age 20.5 ± 2.1 y, height 1.8 ± 0.1 m and body mass [BM] 76.5 ± 9.6 kg) consumed either 0.3 g.kg-1 BM sodium bicarbonate, sodium citrate or a placebo, using a double-blind, randomized crossover design. Blood bicarbonate ion (HCO3-) concentration, pH and GI symptoms were measured pre-consumption and every 10 min for 180 min post-consumption. Blood HCO3- concentration (P < 0.001) and pH (P = 0.040) were significantly higher in the sodium bicarbonate condition compared with sodium citrate condition up to 3 h post-consumption. Peak blood HCO3- concentration was significantly higher with the sodium bicarbonate compared with citrate (P < 0.001). Mean GI symptom scores were lower (P = 0.037) for sodium citrate (1.5 ± 1.8 AU) than bicarbonate (2.6 ± 3.1 AU), with considerable inter-individual variability. No GI symptoms were reported following consumption of the placebo. Both substances increase HCO3- values significantly, with sodium bicarbonate causing significantly higher pH and HCO3- values than the same dose of sodium citrate, but results in slightly more severe GI symptoms.

High dose Nitrate ingestion does not improve 40 km cycling time trial performance in trained cyclists.

This study evaluated the chronic effects of nitrate (NO3-) ingestion over three days, on 40 km TT performance in 11trained cyclists (VO2max: 60.8 ± 7.4 ml.kg-1.min-1; age: 36 ± 9 years; height: 1.80 ± 0.06 m; body mass: 87.2 ± 12.0 kg). Utilising a double-blind randomised cross-over design, participants completed three 40 km TT on a Velotron® ergometer following the ingestion of either a 140 ml of "BEET It sport®" NO3- shot containing 12.8 mmol or 800 mg of NO3-, a placebo drink or nothing (control). Performance, oxygen consumption (VO2), blood bicarbonate (HCO3-), pH and lactate (BLa) and ratings of perceived exertion (RPE) were measured every 10 km throughout the TT. The present findings show that NO3- ingestion had no effect on TT performance (NO3-: 4098.0 ± 209.8 vs. Placebo: 4161.9 ± 263.3 s, p = 0.296, ES = 0.11), or VO2 (p = 0.253, ES = 0.13). Similarly, blood lactate and RPE were also unaffected by the experimental conditions (p = 0.522, ES = 0.06; p = 0.085, ES = 0.30) respectively. Therefore, these results suggest that a high dose of NO3- over three days has limited efficacy as an ergogenic aid for 40 km TT cycling performance in trained cyclists.

Factors influencing ultra-endurance athletes food choices: an adapted food choice questionnaire.

Inadequate nutritional intake has been reported during ultra-endurance training and competition. While substandard nutritional knowledge may contribute to inappropriate nutritional choices, the relationship between these variables is often weak. As such, this study investigated the importance of a range of factors to the food choices of ultra-endurance athletes. An existing food choices questionnaire was extended to reflect the main factors proposed to influence the food choices of these athletes. The questionnaire was pilot tested with endurance athletes, during which, it was refined and reassessed for internal consistency and test-retest reliability. Subsequently, 101 experienced ultra-endurance athletes completed the amended questionnaire. Athletes also documented dietary restrictions or strategies employed in preparation for competition. The factors rated as important by the majority of the athletes were "provides me with energy", "do not cause me gastrointestinal discomfort" and, "are nutritious". Despite the high importance of the provision of energy, only 38.2% of participants reported following a high carbohydrate diet in preparation for competition. In addition, given that nutritious foods are typically high in fibre, it is likely that this factor may conflict with the avoidance of gastrointestinal discomfort. The potential incompatibility of these factors may help explain the observed suboptimal nutritional intake.

Early structured surgical management plan for neonates with short bowel syndrome may improve outcomes.

BACKGROUND: In children with short bowel syndrome, maximal adaptation of the bowel after extensive resection is thought to occur during the first 2 years of life. The aim of the present study was to review children with short bowel syndrome from two intestinal rehabilitation centers, comparing those undergoing lengthening procedures <365 days of age (early) versus those whose lengthening procedure was carried out >365 days of age (late). METHODS: Retrospective data collection was performed from January 2004 to December 2010 in Manchester, UK, and from December 2006 to December 2010 in Brussels, Belgium. Both medical centers follow a similar intestinal rehabilitation program (IRP). Data collected included population demographics, bowel length preoperatively and postoperatively, age at operation, parenteral nutrition (PN), central access, and complications. RESULTS: Complete data were available for eight children who underwent lengthening surgery at <365 days of age, and six who underwent the procedure at >365 days of age. Diagnoses were similar. Groups were matched for gestation and birthweight, with no statistical difference in preoperative and postoperative bowel lengths. The mean duration of PN postoperatively was 378 days in the early cohort and 589 days in the late cohort. This trended toward statistical significance (p = 0.071). Full enteral autonomy was achieved at 17 months (early) and 59 months (late) (p = 0.01). Patients in the early group required fewer central lines than those operated on later (p = 0.035). CONCLUSIONS: Enrolling children into an IRP involving early (<365 days of age) lengthening surgery allows a shorter postoperative time to allow weaning to full enteral nutrition, as well as fewer central lines. Both outcomes provide benefits for the child and family, allowing an earlier return to normal life.

Influence of environmental temperature on duathlon performance.

The aim of this study was to evaluate the physiological, metabolic and performance responses to duathlon performance under a range of ambient temperatures. Ten male recreational athletes performed three self-paced duathlon time trials consisting of a 5 km run (R1), a 30 km cycle and a 5 km run (R2) at 10 degrees C, 20 degrees C and 30 degrees C and a relative humidity of 50%. Performance times, heart rate (HR), rating of perceived exertion (RPE), core temperature (Tc) and skin temperature (Tsk) were measured every kilometre. Carbohydrate and fat oxidation rates were calculated via expired gas analysis at the first and fourth kilometres during both running stages. Blood samples were taken before and after exercise for the determination of prolactin concentration.Overall performance was significantly faster at 10 degrees C (100.76+/-5.32 min) than at 30 degrees C (105.38 +/- 4.28 min). Significantly higher Tc was noted in the 30 degrees C trial than in the 10 degrees C trial, with concomitant elevations in prolactin after exercise (19.88 +/- 6.48 ng/ml at 30 degrees C; 13.10 +/- 8.75 ng/ml at 10 degrees C). The rates of carbohydrate oxidation did not differ between conditions, although fat oxidation rates were highest at 10 degrees C. Elevated ambient temperature has a negative effect on duathlon performance. This effect may be reflected in increased Tc and prolactin concentration.