Table 1 Characteristics of cooling strategies assessed in the included studies.

Barr et al.²⁷

pre/post-cooling

cooling vest (− 30 °C); forearm immersion (~ 19 °C)

treadmill

2 blocks of 20 min walking at 5 km·h⁻¹ and 7.5% incline, separated by 15 min recovery.

T_amb: 49.6 ± 1.8 °C; RH: 13 ± 2%; T_rest: 21 ± 0.5 °C

15

55

Barr et al.³⁹

pre/post-cooling

cooling vest (− 30 °C); forearm immersion (~ 19 °C); combination of both strategies

treadmill

2 blocks of 20 min walking at 5 km·h⁻¹ and 7.5% incline, separated by 15 min recovery.

T_amb: 49.6 ± 1.3 °C; RH: 13 ± 2%; T_rest: 18 °C

15

55

Bennett et al.²⁹

per-cooling

cooling vest (− 28 °C)

active firefighting onboard

40 min active firefighting onboard.

T_amb: 120 °C

40

40

Bennett et al.⁶¹

per-cooling

cooling vest (− 28 °C) (4 and 6 packs)

treadmill

2 blocks of 30 min resting seated, alternating with 2 blocks of 30 min walking at 1.8 km·h⁻¹ and 0% incline.

T_amb: 34.4 ± 0.5 °C; RH: ~70%

120

120

Carter et al.³³

intermittent cooling

fan

step

2 blocks of 10 min stepping (25-30-35 step·min⁻¹), separated by 2 rests of 10 min.

T_amb: 40 ± 1 °C; RH: 70 ± 5%

20

40

Carter et al.³⁴

per/post-cooling

phase-change cooling vest (28 °C); forearm immersion (~ 15 °C)

fire and rescue activity simulation

50 min fire and rescue activity simulation and 20 min recovery.

T_amb: 170 °C; T_rest: 15 °C

20 (post-cooling) 50 (per-cooling)

70

Colburn et al.³⁵

post-cooling

liquid perfused vest; forearm immersion (~ 15 °C)

fire extinguishing activities (NFPA 1403: Live fire evolution)

20 min of fire extinguishing and 30 min of recovery.

T_amb: ~100 °C; T_rest: 22.5 ± 2.9 °C; RH: 47.2 ± 11%

30

50

Constable et al.³⁷

intermittent cooling

liquid perfused vest (~ 13 °C)

treadmill

30 min walking with incline (475 W, 40%VO_2max) alternating with 30 min recovery, until T_core= 39 °C

WBGT = 31 °C

120

240

Frim & Morris³⁰

per-cooling

liquid perfused suit

treadmill

3 work blocks of 10 min walking at 3.5 km·h⁻¹ and 0% incline + 10 min of stacking and unstacking boxes (15 kg) interspersed with 2 rests of 15 min.

T_amb: 34 °C; RH: 40% (Test 1); T_amb: 34 °C; HR: 80% (Test 2)

90

90

Fullagar et al.²⁵

intermittent cooling

forearm immersion (20 °C) + cooling towel + fan (9 km·h⁻¹) + cool water (~ 13 °C); forearm immersion (13 °C) + frozen gel packs + mist fan (9 km·h⁻¹) + ice slurry (− 1 °C)

treadmill and step

2 work blocks of 20 min (walking at 4 km·h⁻¹ and 0%; carrying a 26 kg load while walking; stepping with a 17.5 kg load at 70 step·min⁻¹; isometric grips with tools (19.5 kg); rope hitting; walking 4 km·h⁻¹ and 3.5%; and walking at 4 km·h⁻¹ and 0%, interspersed with 2 blocks of 20 min recovery.

T_amb: 32.0 ± 0.9 °C; RH: 53 ± 3%

40

80

Gao et al.³¹

per-cooling

phase-change cooling vest (24 °C); phase-change cooling vest (28 °C)

treadmill

20 min on a cycle ergometer at 50 W + walking at 5 km·h⁻¹ until 30 min is complete.

T_amb: 55 °C; RH: 30%

50

50

Hagan et a.l³²

per-cooling

liquid perfused vest

treadmill

30 min resting seated + 30 min walking at 4 km·h⁻¹ and 0% incline, repeated until test termination criteria are met.

T_amb: WBGT = 41.0 ± 0.2 °C; RH: 50%

~ 75

~ 75

Ramirez et al.⁶²

per-cooling

cooling vest (− 28 °C)

treadmill

20 min seated rest + 2 blocks of 20 min walking at 4 km·h⁻¹ and 0% alternating with 20 min seated recovery.

T_amb: 48 °C; RH: 50%; Trest: 29 °C; RH_rest: 65%

100

100

Sefton et al.⁶³

post-cooling

mist fan; cooling towel

treadmill

Run at 60%VO_2max until core temperature increases 1.5 °C above baseline or reaches 39 °C + 20 min seated recovery.

T_amb: 32.0 ± 0.5 °C; RH: 75.4 ± 2.6%

20

Selkirk et al.⁴⁰

intermittent cooling

mist fan (7 km·h⁻¹); forearm immersion (17.4 °C)

treadmill

2 blocks of 20 min walking at 4.5 km·h⁻¹ separated by 10 min simulated bottle ERA change + 30 min rest, repeated until test termination criteria are met.

T_amb: 35 °C; RH: 50%

40

~ 180

Selkirk et al.⁶⁴

intermittent cooling

cool water (~ 15 °C)

treadmill

2 blocks of 20 min walking at 4.5 km·h⁻¹ separated by 10 min walking at 2.5 km·h⁻¹ + 30 min rest, repeated until test termination criteria are met.

T_amb: 35 °C; RH: 50%

~ 110

Tabuchi et al.⁶⁵

pre-cooling

ice slurry (− 1.7 °C)

cycle ergometer

10 min cycle ergometer (125 W) + 20 min cycle ergometer (75 W) + 30 min rest

T_amb: 25 °C; RH: 50%; T_rest: 35 °C; RH_rest: 50%

8

70

Walker et al.²⁸

post-cooling

ice slurry (− 1 °C); full-body immersion up to the navel (~ 15 °C)

simulated search and rescue task

2 blocks of 20 min simulated search and rescue tasks separated by 10 min seated recovery + 25 min recovery.

T_amb: 105 ± 5 °C; RH: 38%; T_rest: 19.3 ± 2.7 °C

15

75

Wallace et al.⁶⁶

pre/post-cooling

water perfused hood (~ 13 °C)

treadmill

2 blocks of 20 min walking at 5.6 km·h⁻¹ with 4% incline separated by 20 min seated rest.

T_amb: 35 ± 5 °C; RH: 60%; T_rest: 19.3 ± 2.7 °C

20

60

Yeargin et al.⁴¹

per-cooling; intermittent cooling

frozen gel packs; forearm immersion (5 °C)

simulated fire extinguishing activity

2 blocks of 15 min simulated fire extinguishing tasks separated by 15 min recovery, repeated twice.

T_amb: 33.2 ± 1.5 °C; RH: 27 ± 3%

60 (per-cooling); 30 (intermittent cooling)

90