ORCID Profile
0000-0002-9467-0077
Current Organisation
Deakin University
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Publisher: Public Library of Science (PLoS)
Date: 17-05-2021
DOI: 10.1371/JOURNAL.PONE.0251808
Abstract: To compare blood alkalosis, gastrointestinal symptoms and indicators of strong ion difference after ingestion of 500 mg.kg -1 BM sodium citrate over four different periods. Sixteen healthy and active participants ingested 500 mg.kg -1 BM sodium citrate in gelatine capsules over a 15, 30, 45 or 60 min period using a randomized cross-over experimental design. Gastrointestinal symptoms questionnaires and venous blood s les were collected before ingestion, immediately post-ingestion, and every 30 min for 480 min post-ingestion. Blood s les were analysed for blood pH, [HCO 3 - ], [Na + ], [Cl - ] and plasma [citrate]. Linear mixed models were used to estimate the effect of the ingestion protocols. For all treatments, blood [HCO 3 - ] was significantly elevated above baseline for the entire 480 min post-ingestion period, and peak occurred 180 min post-ingestion. Blood [HCO 3 - ] and pH were significantly elevated above baseline and not significantly below the peak between 150–270 min post-ingestion. Furthermore, blood pH and [HCO 3 - ] were significantly lower for the 60 min ingestion period when compared to the other treatments. Gastrointestinal symptoms were minor for all treatments the mean total session symptoms ratings (all times summed together) were between 9.8 and 11.6 from a maximum possible rating of 720. Based on the findings of this investigation, sodium citrate should be ingested over a period of less than 60 min (15, 30 or 45 min), and completed 150–270 min before exercise.
Publisher: Springer Science and Business Media LLC
Date: 25-10-2023
Publisher: Springer Science and Business Media LLC
Date: 12-2021
DOI: 10.1186/S40798-021-00389-5
Abstract: This study assessed relationships and sex differences between psychological state (recovery, stress, anxiety, and self-confidence) and gastrointestinal symptoms (GIS) prior to and during a 56 km ultramarathon running race and identified predictive factors of race GIS. Forty-four (26 males, 18 females) ultramarathon competitors completed anxiety, recovery, stress and GIS questionnaires for three days prior to the race and immediately pre-race. Race GIS were assessed immediately post-race. Spearman’s rank order, Mann–Whitney U tests and regression analyses were used to determine correlations and identify sex differences between psychological state and GIS and determine predictors of race GIS. Race GIS were significantly correlated with recovery ( r s = − 0.381, p = 0.011), stress ( r s = 0.500, p = 0.001) and anxiety ( r s = 0.408, p = 0.006), calculated as the mean of the three days preceding the race and on race morning. The correlation between anxiety and GIS was strongest in the 24 h immediately prior to the race (all r s 0.400, and all p 0.05), but unclear patterns were identified for stress and recovery. Regression analyses showed 36% and 40% of variation in the severity and number of race GIS was accounted for by body mass and measures of stress, anxiety, and GIS over the three days preceding the race and on race morning (both p 0.001). There were no sex differences in the number and severity of GIS leading up to or during the race (all p 0.05), however, females reported greater state anxiety ( p = 0.018) and lower self-confidence than males ( p = 0.006) over the three days preceding the race and on race morning. Endurance athletes that experience GIS during competition should investigate elevated stress and/or anxiety as a potential contributor and identify if management strategies can reduce the occurrence and severity of GIS.
Publisher: Human Kinetics
Date: 04-2021
Abstract: Purpose : Hot-water immersion (HWI) after training in temperate conditions has been shown to induce thermophysiological adaptations and improve endurance performance in the heat however, the potential additive effects of HWI and training in hot outdoor conditions remain unknown. Therefore, this study aimed to determine the effect of repeated postexercise HWI in athletes training in a hot environment. Methods : A total of 13 (9 female) elite reelite racewalkers completed a 15-day training program in outdoor heat (mean afternoon high temperature = 34.6°C). Athletes were ided into 2 matched groups that completed either HWI (40°C for 30–40 min) or seated rest in 21°C (CON), following 8 training sessions. Pre–post testing included a 30-minute fixed-intensity walk in heat, laboratory incremental walk to exhaustion, and 10,000-m outdoor time trial. Results : Training frequency and volume were similar between groups ( P = .54). Core temperature was significantly higher during immersion in HWI (38.5 [0.3]) than CON (37.8°C [0.2°C] P .001). There were no differences between groups in resting or exercise rectal temperature or heart rate, skin temperature, sweat rate, or the speed at lactate threshold 2, maximal O 2 uptake, or 10,000-m performance ( P .05). There were significant ( P .05) pre–post differences for both groups in submaximal exercising heart rate (∼11 beats·min −1 ), sweat rate (0.34–0.55 L·h −1 ) and thermal comfort (1.2–1.5 arbitrary units), and 10,000-m racewalking performance time (∼3 min). Conclusions : Both groups demonstrated significant improvement in markers of heat adaptation and performance however, the addition of HWI did not provide further enhancements. Improvements in adaptation appeared to be maximized by the training program in hot conditions.
Publisher: Human Kinetics
Date: 03-2021
Abstract: This review aimed to identify factors associated with (a) physiological responses, (b) gastrointestinal (GI) symptoms, and (c) exercise performance following sodium citrate supplementation. A literature search identified 33 articles. Observations of physiological responses and GI symptoms were categorized by dose ( 500, 500, and 500 mg/kg body mass [BM]) and by timing of postingestion measurements (in minutes). Exercise performance following sodium citrate supplementation was compared with placebo using statistical significance, percentage change, and effect size. Performance observations were categorized by exercise duration (very short 60 s, short ≥ 60 and ≤ 420 s, and longer 420 s) and intensity (very high 100% VO 2 max and high 90–100% VO 2 max). Ingestion of 500 mg/kg BM sodium citrate induced blood alkalosis more frequently than 500 mg/kg BM, and with similar frequency to mg/kg BM. The GI symptoms were minimized when a 500 mg/kg BM dose was ingested in capsules rather than in solution. Significant improvements in performance following sodium citrate supplementation were reported in all observations of short-duration and very high–intensity exercise with a 500 mg/kg BM dose. However, the efficacy of supplementation for short-duration, high-intensity exercise is less clear, given that only 25% of observations reported significant improvements in performance following sodium citrate supplementation. Based on the current literature, the authors recommend ingestion of 500 mg/kg BM sodium citrate in capsules to induce alkalosis and minimize GI symptoms. Supplementation was of most benefit to performance of short-duration exercise of very high intensity further investigation is required to determine the importance of ingestion duration and timing.
Publisher: Wiley
Date: 10-2019
DOI: 10.14814/PHY2.14216
Publisher: Human Kinetics
Date: 2023
Abstract: This study compared the recommended dose of sodium citrate (SC, 500 mg/kg body mass) and sodium bicarbonate (SB, 300 mg/kg body mass) for blood alkalosis (blood [HCO 3 − ]) and gastrointestinal symptoms (GIS number and severity). Sixteen healthy in iduals ingested the supplements in a randomized, crossover design. Gelatin capsules were ingested over 15 min alongside a carbohydrate-rich meal, after which participants remained seated for forearm venous blood s le collection and completion of GIS questionnaires every 30 min for 300 min. Time-course and session value (i.e., peak and time to peak) comparisons of SC and SB supplementation were performed using linear mixed models. Peak blood [HCO 3 − ] was similar for SC (mean 34.2, 95% confidence intervals [33.4, 35.0] mmol/L) and SB (mean 33.6, 95% confidence intervals [32.8, 34.5] mmol/L, p = .308), as was delta blood [HCO 3 − ] (SC = 7.9 mmol/L SB = 7.3 mmol/L, p = .478). Blood [HCO 3 − ] was ≥6 mmol/L above baseline from 180 to 240 min postingestion for SC, significantly later than for SB (120–180 min p .001). GIS were mostly minor, and peaked 80–90 min postingestion for SC, and 35–50 min postingestion for SB. There were no significant differences for the number or severity of GIS reported ( p .05 for all parameters). In summary, the recommended doses of SC and SB induce similar blood alkalosis and GIS, but with a different time course.
No related grants have been discovered for Charles Urwin.