Purpose To evaluate the effects of probiotic supplementation on gastrointestinal (GI) symptoms, circulatory markers of GI permeability, damage, and markers of immune response during a marathon race. Methods Twenty-four recreational runners were randomly assigned to either supplement with a probiotic (PRO) capsule [25 billion CFU Lactobacillus acidophilus (CUL60 and CUL21), Bifidobacterium bifidum (CUL20), and Bifidobacterium animalis subs p. Lactis (CUL34)] or placebo (PLC) for 28 days prior to a marathon race. GI symptoms were recorded during the supplement period and during the race. Serum lactulose:rhamnose ratio, and plasma intestinal-fatty acid binding protein, sCD14, and cytokines were measured pre- and post-races. Results Prevalence of moderate GI symptoms reported were lower during the third and fourth weeks of the supplement period compared to the first and second weeks in PRO ( p < 0.05) but not PLC ( p > 0.05). During the marathon, GI symptom severity during the final third was significantly lower in PRO compared to PLC ( p = 0.010). The lower symptom severity was associated with a significant difference in reduction of average speed from the first to the last third of the race between PLC (− 14.2 ± 5.8%) and PRO (− 7.9 ± 7.5%) ( p = 0.04), although there was no difference in finish times between groups ( p > 0.05). Circulatory measures increased to a similar extent between PRO and PLC ( p > 0.05). Conclusion Probiotics supplementation was associated with a lower incidence and severity of GI symptoms in marathon runners, although the exact mechanisms are yet to be elucidated. Reducing GI symptoms during marathon running may help maintain running pace during the latter stages of racing.

Background In this Position Statement, the International Society of Sports Nutrition (ISSN) provides an objective and critical review of the literature pertinent to nutritional considerations for training and racing in single-stage ultra-marathon. Recommendations for Training. i) Ultra-marathon runners should aim to meet the caloric demands of training by following an individualized and periodized strategy, comprising a varied, food-first approach; ii) Athletes should plan and implement their nutrition strategy with sufficient time to permit adaptations that enhance fat oxidative capacity; iii) The evidence overwhelmingly supports the inclusion of a moderate-to-high carbohydrate diet (i.e., ~ 60% of energy intake, 5–8 g·kg− 1·d− 1) to mitigate the negative effects of chronic, training-induced glycogen depletion; iv) Limiting carbohydrate intake before selected low-intensity sessions, and/or moderating daily carbohydrate intake, may enhance mitochondrial function and fat oxidative capacity. Nevertheless, this approach may compromise performance during high-intensity efforts; v) Protein intakes of ~ 1.6 g·kg− 1·d− 1 are necessary to maintain lean mass and support recovery from training, but amounts up to 2.5 g.kg− 1·d− 1 may be warranted during demanding training when calorie requirements are greater; Recommendations for Racing. vi) To attenuate caloric deficits, runners should aim to consume 150–400 Kcal·h− 1 (carbohydrate, 30–50 g·h− 1; protein, 5–10 g·h− 1) from a variety of calorie-dense foods. Consideration must be given to food palatability, individual tolerance, and the increased preference for savory foods in longer races; vii) Fluid volumes of 450–750 mL·h− 1 (~ 150–250 mL every 20 min) are recommended during racing. To minimize the likelihood of hyponatraemia, electrolytes (mainly sodium) may be needed in concentrations greater than that provided by most commercial products (i.e., > 575 mg·L− 1 sodium). Fluid and electrolyte requirements will be elevated when running in hot and/or humid conditions; viii) Evidence supports progressive gut-training and/or low-FODMAP diets (fermentable oligosaccharide, disaccharide, monosaccharide and polyol) to alleviate symptoms of gastrointestinal distress during racing; ix) The evidence in support of ketogenic diets and/or ketone esters to improve ultra-marathon performance is lacking, with further research warranted; x) Evidence supports the strategic use of caffeine to sustain performance in the latter stages of racing, particularly when sleep deprivation may compromise athlete safety.

Our results indicate that both TTP and absolute change in HCO is more reliable than pH. As such, these data provide support for an individualised NaHCO ingestion strategy to consistently elicit peak alkalosis before exercise. Future work should utilise an individualised NaHCO ingestion strategy based on HCO responses and evaluate effects on exercise performance.

Limited research examining the effect of taurine (TA) ingestion on human exercise performance exists. The aim of this study was to investigate the effect of acute ingestion of 1,000 mg of TA on maximal 3-km time trial (3KTT) performance in trained middle-distance runners (MDR). Eight male MDR (mean ± SD: age 19.9 ± 1.2 years, body mass 69.4 ± 6.6 kg, height 180.5 ± 7.5 cm, 800 m personal best time 121.0 ± 5.3 s) completed TA and placebo (PL) trials 1 week apart in a double-blind, randomised, crossover designed study. Participants consumed TA or PL in capsule form on arrival at the laboratory followed by a 2-h ingestion period. At the end of the ingestion period, participants commenced a maximal simulated 3KTT on a treadmill. Capillary blood lactate was measured pre- and post-3KTT. Expired gas, heart rate (HR), ratings of perceived exertion (RPE), and split times were measured at 500-m intervals during the 3KTT. Ingestion of TA significantly improved 3KTT performance (TA 646.6 ± 52.8 s and PL 658.5 ± 58.2 s) (p = 0.013) equating to a 1.7 % improvement (range 0.34-4.24 %). Relative oxygen uptake, HR, RPE and blood lactate did not differ between conditions (p = 0.803, 0.364, 0.760 and 0.302, respectively). Magnitude-based inference results assessing the likeliness of a beneficial influence of TA were 99.3 %. However, the mechanism responsible for this improved performance is unclear. TA's potential influence on exercise metabolism may involve interaction with the muscle membrane, the coordination or the force production capability of involved muscles. Further research employing more invasive techniques may elucidate TA's role in improving maximal endurance performance.

Abstract:Purpose: To examine the influence of an acute dose of sodium bicarbonate (NaHCO3) on buffering capacity and performance during a repeated sprint ability (RSA) protocol. Methods: Eleven (mean ± SD: age 24.6 ± 6.1y; mass 74.9 ± 5.7kg; height 177.2 ± 6.7cm) participated in the study, undertaking four test sessions. On the first visit to the laboratory, each participant ingested 300 mg.kg-1 of NaHCO3 (in 450ml of flavoured water) and blood samples were obtained at regular intervals to determine the individual times peak pH and HCO3-response time. During the subsequent visits, participants ingested either 300mg.kg-1 of NaHCO3, or 270 mg.kg-1 BM of NaCI or no drink followed by a RSA cycling protocol (10 x 6s sprints with 60s recovery), which commenced at each individuals pre-determined ingestion peak pH response time. Blood samples were obtained pre-exercise, and after the 1st, 5th and 10th sprint to determine the blood pH, HCO3-and lactate (La-) responses. Results: The total work completed during the repeated sprint protocol was higher (P < 0.05) in the NaHCO3 condition (69.8 ± 11.7kJ) compared with both the control (59.6±12.2 kJ) and placebo (63.0±8.3 kJ) conditions. Peak power output (PPO) was similar (P > 0.05) between the three conditions. Relative to the control and placebo conditions, NaHCO3 ingestion induced higher (P < 0.05) blood pH and HCO3-concentrations pre-exercise and during the bouts, and higher lactate concentrations (P < 0.05) following the final sprint. Conclusion: The results from the present study suggest that NaHCO3-improves the total amount of work completed during RSA through enhanced buffering capacity. Results:The total work completed during the repeated sprint protocol was higher (P < 0.05) in the NaHCO 3 condition (69.8 ± 11.7kJ) compared with both the control (59.6±12.2 kJ) and placebo (63.0±8.3 kJ) conditions. Peak power output (PPO) was similar (P > 0.05) between the three conditions. Relative to the control and placebo conditions, NaHCO 3 ingestion induced higher (P < 0.05) blood pH and HCO 3 -concentrations pre-exercise and during the bouts, and higher lactate concentrations (P < 0.05) following the final sprint. Conclusion: The results from the present study suggest that NaHCO 3 -improves the total amount of work completed during RSA through enhanced buffering capacity.

Abstract:Studies have established that supplementation of nitrate increases nitrous oxide which in turn improves exercise performance. The current study aimed to investigate the effects of nitrate ingestion on performance of bench press resistance exercise till failure. Twelve recreationally active (age, 21 ± 2yrs, height, 177.2 ± 4.0 cm, weight, 82.49 ± 9.78 kg) resistance trained males participated in the study. The study utilised a double blind randomized cross-over design, where subjects ingested either 70 ml of "BEET It Sport ®" nitrate shot containing 6.4 millimoles (mmol/L) or 400 mg of nitrate; or a blackcurrant placebo drink. Participants completed a resistance exercise session, consisting of bench press exercise at an intensity of 60% of their established 1 repetition maximum (1-RM), for three sets until failure with 2 minute rest interval between sets. The repetitions completed, total weight lifted, local and general rate of perceived exertion (RPE), and blood lactate were all measured. The results showed a significant difference in repetitions till failure (p=<0.001) and total weight lifted (p=<0.001). However there were no significant difference between blood lactate over the two trials (p = 0.238), and no difference in Local (p= 0.807) or general (p= 0.420) indicators of fatigue as measured by RPE. This study demonstrates that nitrate supplementation has the potential to improve resistance training performance and work output compared to a placebo.

Objectives: Whilst the presence of a competitor has been found to improve performance, the mechanisms influencing the change in selected work rates during direct competition have been suggested but not specifically assessed. The aim was to investigate the physiological and psychological influences of a visual avatar competitor during a 16.1-km cycling time trial performance, using trained, competitive cyclists. Design: Randomised cross-over design. Method: Fifteen male cyclists completed four 16.1km cycling time trials on a cycle ergometer, performing two with a visual display of themselves as a simulated avatar (FAM and SELF), one with no visual display (DO), and one with themselves and an opponent as simulated avatars (COMP). Participants were informed the competitive avatar was a similar ability cyclist but it was actually a representation of their fastest previous performance. Results: Increased performance times were evident during COMP (27.8 ± 2.0 min) compared to SELF (28.7 ± 1.9 min) and DO (28.4 ± 2.3 min). Greater power output, speed and heart rate were apparent during COMP trial than SELF (p < 0.05) and DO (p ≤ 0.06). There were no differences between SELF and DO. RPE was unchanged across all conditions. Internal attentional focus was significantly reduced during COMP trial (p < 0.05), suggesting reduced focused on internal sensations during an increase in performance. Conclusions: Competitive cyclists performed significantly faster during a 16.1-km competitive trial than when performing maximally, without a competitor. The improvement in performance was elicited due to a greater external distraction, deterring perceived exertion.

The aim of this study was to investigate the effects of sodium bicarbonate (NaHCO) on 4 km cycling time trial (TT) performance when individualised to a predetermined time to peak blood bicarbonate (HCO). Eleven male trained cyclists volunteered for this study (height 1.82 ± 0.80 m, body mass (BM) 86.4 ± 12.9 kg, age 32 ± 9 years, peak power output (PPO) 382 ± 22 W). Two trials were initially conducted to identify time to peak HCO following both 0.2 gkg BM (SBC2) and 0.3 gkg BM (SBC3) NaHCO. Thereafter, on three separate occasions using a randomised, double-blind, crossover design, participants completed a 4 km TT following ingestion of either SBC2, SBC3, or a taste-matched placebo (PLA) containing 0.07 gkg BM sodium chloride (NaCl) at the predetermined individual time to peak HCO. Both SBC2 (-8.3 ± 3.5 s; p < 0.001, d = 0.64) and SBC3 (-8.6 ± 5.4 s; p = 0.003, d = 0.66) reduced the time to complete the 4 km TT, with no difference between SBC conditions (mean difference = 0.2 ± 0.2 s; p = 0.87, d = 0.02). These findings suggest trained cyclists may benefit from individualising NaHCO ingestion to time to peak HCO to enhance 4 km TT performance.