Due to gastrointestinal tract adaptability, the study aimed to determine the impact of gut-training protocol over 2 weeks on gastrointestinal status, blood glucose availability, fuel kinetics, and ...running performance. Endurance runners (n = 25) performed a gut-challenge trial (GC1), consisting of 2 h running exercise at 60% V̇O
2max
whilst consuming gel-discs containing 30 g carbohydrates (2:1 glucose/fructose, 10% w/v) every 20 min and a 1 h distance test. Participants were then randomly assigned to a carbohydrate gel-disc (CHO-S), carbohydrate food (CHO-F), or placebo (PLA) gut-training group for 2 weeks of repetitive gut-challenge intervention. Participants then repeated a second gut-challenge trial (GC2). Gastrointestinal symptoms reduced in GC2 on CHO-S (60%; p = 0.008) and CHO-F (63%; p = 0.046); reductions were greater than PLA (p < 0.05). H
2
peak was lower in GC2 on CHO-S (mean (CI): 6 (4–8) ppm) compared with CHO-F (9 (6–12) ppm) and PLA (12 (2–21) ppm) (trial × time: p < 0.001). Blood glucose concentration was higher in GC2 on CHO-S (7.2 (6.3–8.1) mmol·L
−1
) compared with CHO-F (6.1 (5.7–6.5) mmol·L
−1
) and PLA (6.2 (4.9–7.5) mmol·L
−1
) (trial × time: p = 0.015). No difference in oxidation rates, plasma I-FABP, and cortisol concentrations were observed between groups and trials. Distance test improved on CHO-S (5.2%) and CHO-F (4.3%) in GC2, but not on PLA (–2.1%) (trial × time: p = 0.009). Two weeks of gut-training with CHO-S and CHO-F improved gastrointestinal symptoms and running performance compared with PLA. CHO-S also reduced malabsorption and increased blood glucose availability during endurance running compared with PLA.
Celotno besedilo
Dostopno za:
DOBA, FSPLJ, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The aim was to test the hypothesis that one night of sleep deprivation will impair pre-loaded 30 min endurance performance and alter the cardio-respiratory, thermoregulatory and perceptual responses ...to exercise. Eleven males completed two randomised trials separated by 7 days: once after normal sleep (496 (18) min: CON) and once following 30 h without sleep (SDEP). After 30 h participants performed a 30 min pre-load at 60%
followed by a 30 min self-paced treadmill distance test. Speed, RPE, core temperature (
T
re
), mean skin temperature (
T
sk
), heart rate (HR) and respiratory parameters (
,
,
, RER pre-load only) were measured. Less distance (
P
= 0.016,
d
= 0.23) was covered in the distance test after SDEP (6037 (759) 95%CI 5527 to 6547 m) compared with CON (6224 (818) 95%CI 5674 to 6773 m). SDEP did not significantly alter
T
re
at rest or thermoregulatory responses during the pre-load including heat storage (0.8°C) and
T
sk
. With the exception of raised
at 30 min on the pre-load, cardio-respiratory parameters, RPE and speed were not different between trials during the pre-load or distance test (distance test mean HR, CON 174 (12), SDEP 170 (13) beats min
−1
: mean RPE, CON 14.8 (2.7), SDEP 14.9 (2.6)). In conclusion, one night of sleep deprivation decreased endurance performance with limited effect on pacing, cardio-respiratory or thermoregulatory function. Despite running less distance after sleep deprivation compared with control, participants’ perception of effort was similar indicating that altered perception of effort may account for decreased endurance performance after a night without sleep.
Purpose
The study aimed to determine the effects of exertional-heat stress on gastrointestinal integrity, symptoms, systemic endotoxin and inflammatory responses; and assess the relationship between ...changes in body temperature and gastrointestinal perturbations.
Methods
Ten endurance runners completed 2 h running at 60%
V
˙
O
2max
in hot (HOT: 35 °C) and temperate (TEMP: 22 °C)-ambient conditions. Rectal temperature (
T
re
) and gastrointestinal symptoms were recorded every 10 min during exercise. Blood samples were collected pre- and post-exercise, and during recovery to determine plasma intestinal fatty acid binding protein (I-FABP), cortisol, bacterial endotoxin and cytokine profile. Calprotectin was determined from pre- and post-exercise faecal samples. Urinary lactulose:
l
-rhamnose ratio was used to measure intestinal permeability.
Results
Compared with TEMP, HOT significantly increased
T
re
(1.4 ± 0.5 vs 2.4 ± 0.8 °C,
p
< 0.001), cortisol (26 vs 82%,
p
< 0.001), I-FABP (127 vs 432%,
p
< 0.001), incidence (70 vs 90%) and severity (58 counts vs 720 counts,
p
= 0.008) of total gastrointestinal symptoms. Faecal calprotectin and circulating endotoxin increased post-exercise in both trials (mean increase 1.5 ± 2.5 µg/g,
p
= 0.032, and 6.9 ± 10.3 pg/ml,
p
= 0.047, respectively), while anti-endotoxin antibodies increased 28% post-exercise in TEMP and decreased 21% in HOT (
p
= 0.027). However, intestinal permeability did not differ between trials (
p
= 0.185). Inflammatory cytokines were greater on HOT compared to TEMP (
p
< 0.05). Increases in
T
re
were positively associated with I-FABP, IL-10, cortisol, nausea and urge to regurgitate (
p
< 0.05).
Conclusions
Exertional-heat stress induces a thermoregulatory strain that subsequently injures the intestinal epithelium, reduces endotoxin clearance capacity, promotes greater cytokinaemia, and development of gastrointestinal symptoms.
It is commonly believed that gastrointestinal issues during exercise are exacerbated by hypohydration. This study aimed to determine the effect of exercise-induced hypohydration on gastrointestinal ...integrity, function, symptoms, and systemic endotoxin and inflammatory profiles. In a randomized crossover design, male endurance runners (
= 11) performed 2 h of running at 70% of maximum oxygen uptake in 25°C ambient temperature with water provision euhydration (EuH) and total water restriction hypohydration (HypoH) during running, which accounted for 0.6 ± 0.6% and 3.1 ± 0.7% body mass loss, respectively. Blood and fecal samples were collected before and after exercise. Breath samples (H
determination) were collected and gastrointestinal symptoms (GIS) recorded before, during, and after exercise. HypoH resulted in a higher, yet insignificant, ∆ preexercise to postexercise plasma cortisol concentration (+286 nmol/l vs. +176 nmol/l;
= 0.098) but significantly higher intestinal fatty acid-binding protein (I-FABP) (+539 pg/ml vs. +371 pg/ml;
= 0.047) concentration compared with EuH. A greater breath H
response (
= 0.026) was observed on HypoH (1,188 ppm/3 h, peak +12 ppm) vs. EuH (579 ppm/3 h, peak +6 ppm). Despite greater GIS incidence on HypoH (82%) vs. EuH (64%), GIS severity scores were not significant between trials. Exercise-induced leukocytosis (overall pre- to postexercise: 5.9 × 10
/l to 12.1 × 10
/l) was similar on both trials. Depressed in vitro neutrophil function was observed during recovery on HypoH (-36%) but not on EUH (+6%). A pre- to postexercise increase (
< 0.05) was observed for circulating cytokine concentrations but not endotoxin values. Hypohydration during 2 h of running modestly perturbs gastrointestinal integrity and function and increases GIS incidence but does not affect systemic endotoxemia and cytokinemia.
Despite anecdotal beliefs that exercise-induced hypohydration exacerbates perturbations to gastrointestinal status, the present study reports only modest perturbations in gastrointestinal integrity, function, and symptoms compared with euhydration maintenance. Exercise-induced hypohydration does not exacerbate systemic endotoxemia and cytokinemia compared with euhydration maintenance. Programmed water intake to maintain euhydration results in gastrointestinal symptom severity similar to exercise-induced hypohydration. Maintaining euhydration during exertional stress prevents the exercise-associated depression in bacterially stimulated neutrophil function.
Off-road running continues to grow in popularity, with differing event categories existing, and terminologies are often used interchangeably and without precision. Trail running, mountain running, ...skyrunning, fell running, orienteering, obstacle course racing and cross-country running all take place predominantly in off-road terrain. Ultramarathon running refers to any running event over marathon distance conducted in any terrain and surface. Although some overlap may exist between these running events, mainly through the common denominator of off-road terrain, distinct features need to be recognised. As scientific interest in these activities grows, it becomes important to clarify these terms and develop a universal language for discussing these events. Similarly, off-road running athletes are generally not properly defined within the scientific literature, which makes intra- and inter-study comparisons difficult. The current position statement of the Ultra Sports Science Foundation highlights the different off-road running events and recommends clear reference to distance, surface, elevation change and altitude, type of event (continuous vs. staged), type of support, name and year of the event, governing body, and guidance on terminology. We further recommend to describe off-road running athletes by basic data, physiological determinants, training and competition characteristics in the scientific literature in order to facilitate and guide further research and practice.
The study aimed to determine the effects of 24-h high (HFOD) and low (LFOD) fermentable oligo-, di-, monosaccharide, and polyol (FODMAP) diets before exertional heat stress on gastrointestinal ...integrity, function, and symptoms. Eighteen endurance runners consumed a HFOD and a LFOD (double-blind crossover design) before completing 2 h of running at 60% maximal oxygen uptake in 35 °C ambient temperature. Blood samples were collected before and after exercise to determine plasma cortisol and intestinal fatty acid binding protein (I-FABP) concentrations, and bacterial endotoxin and cytokine profiles. Breath hydrogen (H
2
) and gastrointestinal symptoms (GIS) were determined pre-exercise, every 15 min during, and in recovery. No differences were observed for plasma cortisol concentration between diets. Plasma I-FABP concentration was lower on HFOD compared with LFOD (p = 0.033). A trend for lower lipopolysaccharide binding protein (p = 0.088), but not plasma soluble CD14 (p = 0.478) and cytokine profile (p > 0.05), responses on HFOD was observed. A greater area under the curve breath H
2
concentration (p = 0.031) was observed throughout HFOD (mean and 95% confidence interval: HFOD 2525 (1452–3597) ppm·4 h
−1
) compared with LFOD (1505 (1031–1978) ppm·4 h
−1
). HFOD resulted in greater severity of GIS compared with LFOD (pre-exercise, p = 0.017; during, p = 0.035; and total, p = 0.014). A 24-h HFOD before exertional heat stress ameliorates disturbances to epithelial integrity but exacerbates carbohydrate malabsorption and GIS severity in comparison with a LFOD.
Novelty
Twenty-four-hour high FODMAP diet ameliorated disturbances to gastrointestinal integrity.
Twenty-four-hour high FODMAP diet results in greater carbohydrate malabsorption compared with low FODMAP diet.
Incidence of GIS during exertional heat stress were pronounced on both low and high FODMAP diets, but greater GIS severity was observed with high FODMAP diet.
Celotno besedilo
Dostopno za:
DOBA, FSPLJ, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Considering the recent growth of exercise gastroenterology research focusing on exercise-induced gastrointestinal syndrome mechanisms, response magnitude, prevention and management strategies, the ...standardized assessment of gastrointestinal symptoms (GIS) is warranted. The current methodological study aimed to test the reliability of a modified visual analog scale for assessing GIS during exercise, in response to a variety of exertional-stress scenarios, with and without dietary intervention. Recreational endurance runners (n = 31) performed one of the three exercise protocols, which included: 2-hr running at 70%
in temperate (24.7 °C) ambient conditions, with fluid restriction; 2-hr running at 60%
in hot (35.1 °C) ambient conditions, while consuming chilled water immediately before and every 15 min during exercise; and 2-hr running at 60%
in temperate (23.0 °C) ambient conditions, while consuming 30 g/20 min carbohydrate (2∶1 glucose∶fructose, 10% temperate w/v), followed by a 1-hr distance test. GIS was monitored pre-exercise, periodically during exercise, and immediately postexercise. After wash out, participants were retested in mirrored conditions. No significant differences (p > .05) were identified between test-retest using Wilcoxon signed-rank test for all GIS (specific and categorized), within each exercise protocol and the combined protocols. Strong correlations were observed for gut discomfort, total GIS, upper GIS, and nausea (r
= .566 to r
= .686; p < .001), but not for lower GIS (r
= .204; p = .232). Cohen's magnitude of difference was minimal for all GIS (specific δ < 0.14 and categorized δ < 0.08). The modified visual analog scale for assessing GIS during exercise appears to be a reliable tool for identifying incidence and severity of GIS in cohort populations and is sensitive enough to detect exertional and intervention differences.
The International Association of Athletics Federations recognizes the importance of nutritional practices in optimizing an Athlete's well-being and performance. Although Athletics encompasses a ...diverse range of track-and-field events with different performance determinants, there are common goals around nutritional support for adaptation to training, optimal performance for key events, and reducing the risk of injury and illness. Periodized guidelines can be provided for the appropriate type, amount, and timing of intake of food and fluids to promote optimal health and performance across different scenarios of training and competition. Some Athletes are at risk of relative energy deficiency in sport arising from a mismatch between energy intake and exercise energy expenditure. Competition nutrition strategies may involve pre-event, within-event, and between-event eating to address requirements for carbohydrate and fluid replacement. Although a "food first" policy should underpin an Athlete's nutrition plan, there may be occasions for the judicious use of medical supplements to address nutrient deficiencies or sports foods that help the athlete to meet nutritional goals when it is impractical to eat food. Evidence-based supplements include caffeine, bicarbonate, beta-alanine, nitrate, and creatine; however, their value is specific to the characteristics of the event. Special considerations are needed for travel, challenging environments (e.g., heat and altitude); special populations (e.g., females, young and masters athletes); and restricted dietary choice (e.g., vegetarian). Ideally, each Athlete should develop a personalized, periodized, and practical nutrition plan via collaboration with their coach and accredited sports nutrition experts, to optimize their performance.
ObjectivesThis study aimed to determine the impact of running and cycling exercise modalities on the magnitude of exercise-induced gastrointestinal syndrome (EIGS) and associated gastrointestinal ...symptoms (GIS).DesignParallel group trial design.MethodsTwenty-eight endurance athletes (male n = 14, female n = 14) completed 2 h running at 55 % of maximal oxygen uptake or cycling at 55 % of maximal aerobic power in Tamb 35 °C and 22 % RH. Pre- and post-exercise blood samples were collected and analysed for markers of intestinal epithelial integrity perturbations (i.e., plasma intestinal fatty acid protein (I-FABP), soluble (s)CD14, and lipopolysaccharide binding protein (LBP)) and systemic inflammatory cytokines (i.e., plasma IL-1β, TNFα, IL-10, and IL-1ra). GIS were assessed pre-exercise and every 10 min during exercise.ResultsExercise-associated Δ for plasma I-FABP (191 and 434 pg‧ml−1) and LBP (−1228 and 315 ng‧ml−1) did not differ between running and cycling, respectively; however for sCD14 was higher (p = 0.030) on cycling (116 ng‧ml−1) vs running (96 ng‧ml−1). There were no differences in absolute pre- and post-exercise systemic inflammatory cytokine concentration, with large individual variation observed. Exercise-associated plasma TNF-α, (p = 0.041) and IL-10 (p = 0.019) responses were greater in running than cycling, but did not lead to a greater systemic inflammatory response profile (p = 0.305) between running (5.0arb.units) and cycling (−2.5arb.units). Although greater GIS incidence occurred in running (44 %) compared with cycling (25 %), there was no difference between groups for GIS severity.ConclusionsWhen running and cycling exercise is performed with similar duration, intensity, ambient conditions, and with confounder control, the exercise modality does not substantially impact the magnitude of EIGS or associated GIS severity.
Ultra-endurance activities (≥ 4h) present unique challenges that, beyond fatigue, may be exacerbated by sub-optimal nutrition during periods of increased requirements and compromised gastrointestinal ...function. The causes of fatigue during ultra-endurance exercise are multi-factorial. However, mechanisms can potentially include central or peripheral fatigue, thermal stress, dehydration, and/or endogenous glycogen store depletion; of which optimising nutrition and hydration can partially attenuate. If exercise duration is long enough (e.g. ≥ 10h) and exercise intensity low enough (e.g. 45-60% of maximal oxygen uptake), it is bio-energetically plausible that ketogenic adaptation may enhance ultra-endurance performance, but this requires scientific substantiation. Conversely, the scientific literature has consistently demonstrated that daily dietary carbohydrates (3-12g/kg/day) and carbohydrate intake (30-110g/h) during ultra-endurance events can enhance performance at individually tolerable intake rates. Considering gastrointestinal symptoms are common in ultra-endurance activities, effective dietary prevention and management strategies may provide functional, histological, systemic, and symptomatic benefits. Taken together, a well-practiced and individualized fuelling approach is required to optimize performance in ultra-endurance events.
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