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Table 2 Study characteristics

From: Sustainable solutions to mitigate occupational heat strain – an umbrella review of physiological effects and global health perspectives

Author (year) Aim Number of studies Number of participants Cooling Interventions Study context Type of analysis
Adams 2014 [91] Evaluate the change in heart rate for every 1% loss in body mass 20 a188
(173 M, 15 F)
Hydration Athletic performance ES + MR
Alhadad 2019 [93] Evaluate heat mitigation strategies to lower core temperature pre, mid and post exercise 123 a1470
(1382 M, 88 F)
Aerobic fitness, heat acclimation (low and high humidity), fluid ingestion (ad libitum, low and high consumption, hypohydrated, euhydrated), pre-cooling (cold water immersion, cold air exposure, cooling vests, cold fluid ingestion, ice slurry ingestion) Athletic performance ES
Best 2018 [80] Meta-analyze the effect of internal and external cooling methods applied before and during exercise on performance 10 a101
(101 M, 0 F)
Ice slurry ingestion, ice towels, oral rehydration, water dousing, external menthol application, cold fluids with menthol Athletic performance ES
Bongers 2015 [89] Evaluate precooling and percooling on exercise performance and thermoregulatory responses 28 a261
(283 M, 8 F)
Cooling vest, cold water immersion, cold water ingestion, cooling packs, mixed methods Athletic performance ES + MR
Born 2013 [88] Summarize evidence concerning compression garments on performance and recovery b3 30
(30 M, 0 F)
Compression garments Athletic performance ES
Brearley 2015 [81] Efficacy of water immersion in firefighting settings to rapidly reduce core temperature 43 642
(517 M, 125 F)
Limb immersion Firefighters QUAL
Burdon 2010 [86] Determine whether ingesting cool beverages lowers core temperature and improves athletic performance 10 86
(86 M, 0 F)
Cold fluid ingestion Athletic performance ES
Burdon 2012 [84] Effect of beverage temperature on drink palatability 11 233
(208 M, 25 F)
Fluid ingestion Athletic performance ES
Chalmers 2014 [65] Investigate the effect of short term heat acclimation on physical performance 8 98
(79 M, 19 F)
Short term heat acclimation Athletic performance QUAL
Chan 2015 [73] Determine the effectiveness of multiple microenvironment cooling systems on physical performance 32 235
(231 M, 4 F)
Phase change garments, air cooled garments, cold-air cooled garments, liquid cooled garments, hybrid cooling garments, local cooling packs, cooling packs on neck and head Sport, military, chemical protection, firefighting, and occupational health ES + MR
Choo 2018 [79] Effect of cold water immersion and ingestion on psychophysiological and athletic performance 22 245
(213 M, 32 F)
Cold water immersion, ice slurry ingestion Athletic performance ES
Daanen 2018 [64] Systematically review and analyze heat acclimation decay and reacclimation 21 449
(428 M, 21 F)
Heat acclimation (decay) Athletic performance MR
Douzi 2019 [75] Evaluate effect of various methods of percooling on aerobic and anaerobic performance 36 a,c379
(356 M, 23 F)
Neck cooling, air-ventilation, cold fluid ingestion, ice vests, cooling garments Athletic performance ES
Goodman 2019 [70] Meta-analyze the effect of active hypohydration on cognitive performance 10 179
(124 M, 55 F)
Hypohydration Cognitive performance ES
Goulet 2011 [85] Effect of exercise induced dehydration on time trial performance 5 39
(32 M, 7 F)
Exercise induced dehydration Athletic performance ES + MR
Hefferman 2019 Systematically review trace mineral element supplementation on athletic performance e15 a377
(328 M, 49 F)
Sodium supplementation Athletic performance QUAL
Holland 2017 [67] Determine effect of fluid ingestion on exercise performance 9 71
(64 M, 7 F)
Fluid ingestion Athletic performance ES + MR
Jeffries 2019 [77] Meta-analyze the effect of menthol use on athletic performance and psychophysiological responses 11 126
(126 M, 0 F)
Internal and external menthol application Athletic performance ES
Jones 2012 [66] Summarize the effectiveness of pre cooling methods 13 119
(108 M, 11 F)
Cold water immersion, cooling garment, cold water ingestion, ice slurry ingestion, leg cooling Athletic performance ES
Junge 2016 [95] The effect of environmental heat stress factors on cycling time trial performance 14 a145
(131 M, 14 F)
Environmental conditioning Athletic and occupaltional performance MR
Martin 2019 [94] Environmental heat stress on cognitive and military task performance f31 a683
(563 M, 120F)
Environmental heat stress Cognitive and military task performance QUAL
McCartney 2017 [68] Fluid intake following dehydration on physical and cognitive performance 64 643
(598 M, 45 F)
Fluid ingestion Athletic performance ES
McDermott 2009 [88] Evaluate the effect of whole-body methods for reducing exercise induced hyperthermia 7 a68
(56 M, 12 F)
Cold water immersion, wet towels, cold air exposure, skin wetting with fan use, ice packs, Athletic performance QUAL
McEntire 2013 [83] Systematically review cooling techniques and practices among firefighters 27 a308
(287 M, 21 F)
Passive cooling in air, hand and arm immersion, foot immersion, cooling vests, hand cooling, intravenous cooling, fanning, fanning with misting, cooling sock, liquid and air cooled suits, Firefighters QUAL
Rahimi 2019 [78] Heat acclimation on athletic performance and psychophysiological responses 11 215
(195 M, 20 F)
Heat acclimation Athletic performance ES
Ranalli 2010 [74] Effect of body cooling on exercise performance c9 a107
(92 M, 15 f)
Ice vest, cold water immersion, cooling collar Athletic performance %Increase
Ross 2013 [97] Evaluate the established pre-cooling literature 64 631
(587 M, 44 F)
Cold air, cold water immersion, cooling packs, cooling vests, ice towels, cold water ingestion, cold air inhalatiion Athletic performance QUAL
Ruddock 2017 [72] Does cooling during exercise decrease physiological strain and improve exercise performance 15 135
(135 M, 0 F)
Cold fluid, ice slurry, neck cooling collar, hand cooling, Athletic performance ES
Stearns 2010 [87] Meta-analyze the effect of protein and carbohydrate ingestion on exercise performance d1 a13
(7 M, 6 F)
Protein ingestion Athletic performance QUAL
Tomes 2017 [71] Effect of wearing protective body armour 16 433
(353 M, 80 F)
Clothing variety (protective) Law enforcement personnel wellbeing QUAL
Tyler 2015 [90] Effect of pre and percooling on exercise performance and capacity in the heat 38 335
(318 M, 17 F)
Mist and fan, ice vest, neck cooling collar Athletic performance ES
Tyler 2016 [69] Effect of heat acclimation on physiological, perceptual and performance variables 96 1056
(980 M, 76 F)
Heat acclimation Athletic performance ES
Vandenbogaerde 2011 Conduct a meta-analysis to determine the effect of carbohydrates on athletic performance 154 1628
(1469 M, 159 F)
Carbohydrate ingestion Athletic performance MR
Walker 2016 [96] Investigate the effect of fighting fires on hydration status 10 225
(214 M, 11 F)
Hydration Firefighter hydration QUAL
Wegmann 2012 [92] Effect of pre cooling on sport performance 27 268
(260 M, 8 F)
Cooling vest, cold water immersion, skin wetting, cooling packs, cold water ingestion, cold air Athletic performance ES
Wittbrodt 2018 [98] Determine the impact of dehydration on cognitive performance 33 463
(396 M, 67 F)
Hydration Athletic and occupational cognitive performance ES + MR
  1. M Male; F Female; ES Effect size; MR Meta-regression; QUAL Qualitative analysis
  2. a Distribution of male and female participants determined from the original investigations
  3. b Only includes studies examining the effect of core temperature as exercise performance was conducted in temperate conditions
  4. c Includes only the studies examining effect on aerobic performance/ excludes anaerobic performance
  5. d While this review examined and meta-analysed the results of 11 studies, they marked that protein ingestion was only
  6. e Number of studies pertaining to sodium ingestion only
  7. f Number of studies pertaining to the heat only