Science
The research the BLOCKS assistant answers from: 1,118 studies and 81 guides, each graded for how strong the evidence is and who it was measured on, with a link to the original paper.
43 entries in Heat, altitude & travel
A-Pooled over 211 heat-acclimation papers, the typical block is 8 ± 4 exposures of 90 ± 36 min and buys a 3.1% time-trial gainAnd adding sessions buys a different adaptation from making sessions longerMcDonald 2025APolicy statement — Climatic heat stress and exercising children and adolescents (American Academy of Pediatrics): contrary to previous thinking, youth do not thermoregulate worse, have less cardiovascular capacity or tolerate exertion less than adults in the heat when adequately hydrated; the main risks are poor hydration, undue exertion, too little recovery between bouts or same-day sessions, and heat-retaining clothing and equipment — all modifiable, so exertional heat illness is usually preventableBergeron 2011C+Expert review of sport in the cold: the heat produced by exercise reduces the clothing needed, athletes should not overdress, and warm-up warmth should be kept with insulating clothing until the startOverdressing itself has not been studiedGatterer 2021BRain at 5 °C makes even hard running colder and costlier: rectal temperature was lower from 10 minutes, and oxygen uptake and perceived exertion were higher by 50–60 minutesIto 2019BIn a thin full-body race suit with a 5 m/s wind, hard running was best at −4 to +1 °C and already impaired at +10 °CThe best temperature depends on what is wornSandsund 2012BAt about 70% VO2max in still air, cycling time to exhaustion was longest at 10.5 °C (93.5 min) and shortest at 30.5 °C (51.6 min)An inverted U with temperatureGalloway & Maughan 1997BMarathon performance slows progressively as WBGT rises from 5 to 25 °CTop men were 1.7% off the course record in the 5–10 °C band and 4.5% off at 20–25 °C — and slower runners lose moreEly 2007B+Defining the "dose" of altitude training: how high to live for optimal sea level performance enhancementChapman 2014BPre-Altitude Serum Ferritin Levels and Daily Oral Iron Supplement Dose Mediate Iron Parameter and Hemoglobin Mass Responses to Altitude ExposureGovus 2015BOne hour of internal precooling with cold water/menthol enhances cycling performance in a heat/wet stress environment: A pilot studyRinaldi 2023BPhysical and Perceptual Cooling with Beverages to Increase Cycle Performance in a Tropical ClimateRiera 2014BPerceptual, Thermoregulatory, and Performance Effects of Menthol Gel Application in Trained Triathletes Exercising in Hot ConditionsBarwood 2025BEnhancement of Exercise Capacity in the Heat With Repeated Menthol-Spray ApplicationBarwood 2019A-Effects of different menthol administration routes on endurance performance and physiological responses in the heat: a network meta-analysisZhu 2026A-Acute topical menthol application and exercise performance: A systematic review and meta-analysis of perceptual and physiological responsesWang 2026A-How Cool is That? The Effects of Menthol Mouth Rinsing on Exercise Capacity and Performance: A Systematic Review and Meta-analysisGavel 2024A-The effects of menthol on exercise performance and thermal sensation: A meta-analysisJeffries & Waldron 2019B+Heat training raises haemoglobin mass reliably and performance only slightlySo it is a plausible substitute for an altitude camp, chosen per athlete by what they tolerate, and it belongs late in the priority list rather than earlyLundby & Robach 2025BChronic pill use impairs the sweating response in the heatThe sudomotor threshold and thermosensitivity are both blunted versus naturally cycling athletes, so an athlete on the pill is not simply "a cycle that got standardised"Lei 2019BSex differences in sweating appear only above a high heat-loss requirement, come from sweat gland OUTPUT rather than gland recruitmentAnd there is no sex difference in skin blood flowGagnon & Kenny 2012BIn well-trained women, cycle phase did NOT affect performance in the heatHumidity did, costing 7% of work doneLei 2017BMenstrual cycle phase cost endurance performance in hot, humid conditions but not in temperate onesThe environment decides whether the cycle shows up at allJanse de Jonge 2012B+The luteal phase raises core temperature before and throughout exercise in the heatBut sweat rate, skin temperature and exercise heart rate do not differ between cycle phasesGiersch 2020BThe spread in altitude losses is not random: the higher the sea-level VO₂max and lactate threshold, the LARGER the decline at a simulated 3000 mThe fittest athletes lose the mostKoistinen 1995BAerobic performance declines LINEARLY with altitudeAbout −6.3% VO₂max per 1000 m — and the loss is already statistically significant at 800 m: there is no threshold below which altitude is freeWehrlin & Hallén 2006CFebrile illness in the athleteFever means STOP: no consensus supports returning before the fever resolves, and training resumes gradually once fever and dehydration have clearedDick & Diehl 2013BDaytime napping in athletes — systematic review of 37 studies: naps may benefit physical and cognitive performance, perception, psychological state and night sleep; 20-90 min between 13:00 and 16:00, with 30 min to clear sleep inertia before trainingLastella 2021C+Air pollution harms athlete airway and cardiovascular healthFresh traffic and ice-resurfacer exhaust are the biggest concern; the performance evidence is thinRundell 2012BPhysical & cognitive performance vary with time of day AND chronotype"night owls" are impaired in the morning on every measure vs early typesFacer-Childs 2018AManaging travel fatigue and jet lag in athletes: review & consensus statement (26-expert panel)Janse van Rensburg 2021B+Cold Acclimatization — human physiological responses to cold exposureCastellani & Young 2016B+Heat Acclimation — adaptations and mechanisms (the defining review)Périard 2015BA Warm Environment Reduces Exogenous Glucose Oxidation and Endurance Performance during Cycling with Facing Airflow32 °C vs 19 °C with realistic airflow: exogenous glucose oxidation −14-15%, ~15-min TT 15% slowerReynolds 2024BThe Effects of Palmar Cooling on Repeated Sprinting Ability: A Randomized Controlled Clinical TrialBrown M 2025ASea-level exercise performance following adaptation to hypoxia: a meta-analysis51 studies, six protocols; in subelite athletes natural live-high-train-low gave +4.2% (±2.9%) and brief intermittent artificial LHTL +2.6% (±1.2%) in maximal endurance power; in elite athletes only…Bonetti & Hopkins 2009B+Combining Hypoxic Methods for Peak PerformanceMillet 2010BLong-term passive heat acclimation enhances maximal oxygen consumption via haematological and cardiac adaptation in endurance runners5 weeks of hot-water immersion (5 × 45 min/week, ≥40 °C) in 10 well-trained runners: Hb mass +33 g, blood volume +284 mL, LVEDV +10 mL, VO2max +2.7 mL/kg/min, speed at VO2max +0.8 km/hJenkins 2025C+Cooling interventions for athletes: effectiveness, mechanisms and practical considerationsBongers 2017A-Pre-cooling and sports performance: a meta-analytical reviewWegmann 2012A-Cooling prior to and during exercise in the heat: meta-analysis (Tyler 2013)Tyler 2015