The Effect of Heat Stress and Dehydration on Carbohydrate Use During Endurance Exercise: A Systematic Review and Meta-Analysis.

Background: Carbohydrate metabolism during prolonged endurance exercise can be influenced by heat stress and dehydration. While heat exposure and dehydration have been shown to independently affect glycogen use and carbohydrate oxidation, their combined impact remains unclear. No previous review has systematically evaluated the effects of these factors on carbohydrate metabolism during prolonged endurance exercise or undertaken a meta-analysis.

Factors Affecting V̇O and Fat Oxidation Responses During Step Incremental Exercise.

Step incremental exercise tests are widely used to assess endurance performance determinants; however, to what extent step duration influences oxygen uptake (V̇O) and carbon dioxide production (V̇CO) is unclear. This study assessed the influence of sampling duration on V̇O, V̇CO, and fat oxidation (Fat) across different exercise intensities and modalities, and participant age and biological sex during graded exercise tests. A total of 169 participants (41 females; peak V̇O [V̇Opeak]: 54.

Twice a Day Lacrosse Training in Temperate Conditions Results in a Negative 24-Hour Sodium Balance in Male and Female University Lacrosse Players.

Macrae, HZ, Reynolds, KM, Cable, TG, Barutcu, A, Hansell, EJ, Mears, SA, Midwood, KL, Mould, C, Funnell, MP, Goosey-Tolfrey, VL, and James, LJ. Twice a day lacrosse training in temperate conditions results in a negative 24-hour sodium balance in male and female university lacrosse players. J Strength Cond Res 39(9): e1091-e1098, 2025-This study measured 24-hour fluid and sodium balance in 27 university lacrosse players (13 males, 14 females; 21 ± 1 years).

Gastrointestinal Temperature Measurement From Ingestible Pills Provided 3 Hours Preexercise Is Insufficient to Avoid Interference Caused by Tepid Water Ingestion.

Purpose: This study aimed to evaluate the effect of telemetric-pill ingestion timing on gastrointestinal temperature measurements during exercise with tepid fluid intake.

Methods: Twelve participants swallowed temperature pills 12, 3, or 0.5 hours before completing 60 minutes of treadmill running, consuming 200 mL of room-temperature water every 15 minutes.

24 h severe fluid restriction increases a biomarker of renal injury in healthy males.

Purpose: Exercise-induced hypohydration exacerbates biomarkers of renal injury, but studies isolating the effects of hypohydration without exercise have produced mixed findings. This study investigated the effects of 24-h severe fluid restriction on biomarkers of renal injury and glucose tolerance.

Methods: Fifteen males (age: 27 ± 5 y; BMI: 24.

Running in the heat similarly reduces lipid oxidation and peak oxygen consumption in trained runners and inactive individuals.

This study compared oxygen consumption and substrate oxidation while exercising in hot and temperate conditions in individuals with different physical activity statuses (i.e., inactive individuals vs.

7 days of L-citrulline supplementation does not improve running performance in the heat whilst in a hypohydrated state.

Purpose: 7 days L-citrulline supplementation has been reported to improve blood pressure, O kinetics, gastrointestinal (GI) perfusion and endurance cycling performance through increasing arterial blood flow. In situations where blood volume is compromised (e.g.

A Warm Environment Reduces Exogenous Glucose Oxidation and Endurance Performance during Cycling with Facing Airflow.

Purpose: This study investigated the effect of cycling in a warm versus temperate environment with sufficient facing airflow on exogenous glucose use, performance, and GI responses.

Methods: Ten trained male cyclists/triathletes (36 ± 6 yr; 55 ± 6 mL·kg -1 ·min -1 ) completed V̇O 2peak and familiarization trials, and two experimental trials in 19°C (TEMP) and 32°C (WARM). Experimental trials involved 2-h cycling at ~50% W peak (preload) and an ~15-min time trial (TT) with fan-provided airflow covering the cyclist (preload ~29 km·h -1 , TT ~35 km·h -1 ).

Environmental challenges facing athletes, stakeholders and spectators at Paris 2024 Olympic and Paralympic Games: an evidence-based review of mitigation strategies and recommendations.

The upcoming Paris 2024 Olympic and Paralympic Games could face environmental challenges related to heat, air quality and water quality. These challenges will pose potential threats to athletes and impact thousands of stakeholders and millions of spectators. Recognising the multifaceted nature of these challenges, a range of strategies will be essential for mitigating adverse effects on participants, stakeholders and spectators alike.

Fluid and electrolyte balance following consumption of skimmed milk and a plant-based soya beverage at rest in euhydrated males.

Purpose: Cow's milk is one of the most hydrating beverages, but many individuals choose not to consume dairy in their diet due to intolerance, allergy, or dietary preference. Milk is commonly replaced with plant-based beverages, including soya which has the most comparable protein content, but little is known about their hydration potential. This study compared fluid and electrolyte balance responses between a soya beverage and skimmed cow's milk.

Iterative assessment of a sports rehydration beverage containing a novel amino acid formula on water uptake kinetics.

Purpose: Rapid gastric emptying and intestinal absorption of beverages is essential for rapid rehydration, and certain amino acids (AA) may augment fluid delivery. Three sugar-free beverages, containing differing AA concentrations (AA + PZ), were assessed for fluid absorption kinetics against commercial sugar-free (PZ, GZ) and carbohydrate-containing (GTQ) beverages.

Methods: Healthy individuals (n = 15-17 per study) completed three randomised trials.

Perceived dehydration impairs endurance cycling performance in the heat in active males.

Dehydration of >3 % body mass impairs endurance performance irrespective of the individual's knowledge of their hydration status, but whether knowledge of hydration status influences performance at lower levels of dehydration is unknown. This study examined whether perception of hydration status influenced endurance performance. After familiarisation, nine active males (age 25 ± 2 y, V̇O 52.

A self-paced 15-minute cycling time trial is a reliable performance measure in recreationally active individuals.

Cycling time trial (TT) protocols have been shown to be reliable in trained cyclists, but their reproducibility in lesser-trained individuals is unknown. This study examined the reliability of a self-paced 15-minute cycling TT in recreationally active individuals. Twelve recreationally active males (age 27 ± 3 y; body mass 75.

Hypohydration induced by prolonged cycling in the heat increases biomarkers of renal injury in males.

Purpose: Recent studies have shown that hypohydration can increase renal injury. However, the contribution of hypohydration to the extent of renal injury is often confounded by exercise induced muscle damage. Therefore, the aim of the present study was to investigate the effect of manipulating hydration status during moderate-intensity cycling in the heat on biomarkers of renal injury.

Exercise-induced hypohydration impairs 3 km treadmill-running performance in temperate conditions.

Research assessing exercise-induced hypohydration on running performance in a temperate environment is scarce. Given the weight-bearing nature of running, the negative effects of hypohydration might be offset by the weight-loss associated with a negative fluid balance. Therefore, this study investigated the effect of exercise-induced hypohydration on running performance in temperate conditions.

Post-exercise rehydration: Comparing the efficacy of three commercial oral rehydration solutions.

Introduction: This study compared the efficacy of three commercial oral rehydration solutions (ORS) for restoring fluid and electrolyte balance, after exercise-induced dehydration.

Method: Healthy, active participants ( = 20; ♀ = 3; age ∼27 y, Opeak ∼52 ml/kg/min) completed three randomised, counterbalanced trials whereby intermittent exercise in the heat (∼36°C, ∼50% humidity) induced ∼2.5% dehydration.

Ad-libitum fluid intake was insufficient to achieve euhydration 20 h after intermittent running in male team sports athletes.

This study documented 20 h rehydration from intermittent running while concealing the primary outcome of rehydration from subjects. Twenty-eight male team sports athletes (age 25 ± 3 y; predicted V̇O 54 ± 3 mL kg min) were pair-matched to exercise (EX) or rest (REST) groups. To determine hydration status, body mass, urine and blood samples were collected at 08:00, pre-intervention (09:30), post-intervention (12:00), 3 h post-intervention and 08:00 the following morning (20 h).

Apple puree as a natural fructose source provides an effective alternative carbohydrate source for fuelling half-marathon running performance.

Carbohydrate supplementation during endurance exercise is known to improve performance, but the effects of food-based approaches in running exercise are understudied. Therefore, this study investigated the performance and gastrointestinal (GI) effects of a carbohydrate supplement containing a natural fructose source compared with a highly processed fructose source in a combined glucose-fructose supplement, during a half-marathon. Eleven trained runners (9 males, 2 females; age 32 ± 8 y, 89:53 ± 13:28 min half-marathon personal record) completed a familiarisation (8 miles) and two experimental trials (13.

The impacts of sport emissions on climate: Measurement, mitigation, and making a difference.

As a global industry, sport makes potentially significant contributions to climate change through both carbon emissions and influence over sustainability practices. Yet, evidence regarding impacts is uneven and spread across many disciplines. This paper investigates the impacts of sport emissions on climate and identifies knowledge gaps.

A Food First Approach to Carbohydrate Supplementation in Endurance Exercise: A Systematic Review.

This systematic review analyzed whether carbohydrate source (food vs. supplement) influenced performance and gastrointestinal (GI) symptoms during endurance exercise. Medline, SPORTDiscus, and citations were searched from inception to July 2021.

Hypohydration produced by high-intensity intermittent running increases biomarkers of renal injury in males.

Purpose: Whilst there is evidence to suggest that hypohydration caused by physical work in the heat increases renal injury, whether this is the case during exercise in temperate conditions remains unknown. This study investigated the effect of manipulating hydration status during high-intensity intermittent running on biomarkers of renal injury.

Methods: After familiarisation, 14 males (age: 33 ± 7 years; V̇O: 57.

Effects of Exercise on Acute Kidney Injury Biomarkers and the Potential Influence of Fluid Intake.

Acute kidney injury (AKI) incidence (diagnosed by changes in serum creatinine [Cr]) following prolonged endurance events has been reported to be anywhere from 4 to 85%, and hypohydration may contribute to this. Whilst an increase in serum Cr indicates impaired kidney function, this might be influenced by muscle damage. Therefore, the use of other AKI biomarkers which can detect renal tubular injury may be more appropriate.

Sports Drink Intake Pattern Affects Exogenous Carbohydrate Oxidation during Running.

Purpose: This study aimed to determine whether the pattern of carbohydrate sports drink ingestion during prolonged submaximal running affects exogenous carbohydrate oxidation rates and gastrointestinal (GI) comfort.

Methods: Twelve well-trained male runners (27 ± 7 yr; 67.9 ± 6.

Addition of sodium alginate and pectin to a carbohydrate-electrolyte solution does not influence substrate oxidation, gastrointestinal comfort, or cycling performance.

Eight well-trained cyclists ingested 68 g·h of a carbohydrate-electrolyte solution with sodium alginate and pectin (CHO-ALG) or a taste and carbohydrate type-matched carbohydrate-electrolyte solution (CHO) during 120 min of cycling at 55% maximal power followed by an ∼20 min time trial. Oxygen uptake, carbon dioxide production, blood glucose concentration, substrate oxidation, gastrointestinal symptoms, and time trial performance (CHO-ALG: 1219 ± 84 s, CHO: 1267 ± 102 s; = 0.185) were not different between trials.

Does Hypohydration Really Impair Endurance Performance? Methodological Considerations for Interpreting Hydration Research.

The impact of alterations in hydration status on human physiology and performance responses during exercise is one of the oldest research topics in sport and exercise nutrition. This body of work has mainly focussed on the impact of reduced body water stores (i.e.