Table 4 Participant characteristics for each included study

Arngrïmsson et al., 2004 [24]

Competitive collegiate and club middle/long distance runners

Age men: 23.4 (4.4) years

Age women: 22.1 (2.2) years

Height men: 178.6 (4.4) cm

Height women: 167.7 (5.5) cm

Body mass men: 67.7 (4.2) kg

Body mass women: 55.9 (4.3) kg

Body fat men: 7.3 (2.0) %

Body fat women: 17.8 (3.3) %

Best 5 km run time men: 15.5 (0.8) min

Best 5 km run time women: 17.9 (1.1) min

VO₂max men: 4.50 (0.31) l/min

VO₂max women: 3.24 (0.25) l/min

Heat acclimatized

Booth et al., 1997 [42]^a

Competitive runners from a local athletic club

Age: 26.7 (1.7) years

Height: 169.7 (4.0) cm

Weight: 65.96 (2.87) kg

Sum of eight skinfolds: 62.5 (9.7) mm

Body surface area: 1.75 (0.06) m²

Body fat: 15.8 (1.2) %

HR_max: 189.5 (2.8) beats/min

VO₂peak: 63.1 (0.1) ml/kg/min

Non-heat acclimatized

Cotter et al., 2001 [25]

Habitually active, but were of lower average aerobic fitness than subjects used in previous studies on the effects of pre-cooling

Age: 32.4 (3.6) years

Height: 175.6 (6.9) cm

Body mass: 80.9 (10.5) kg

Body surface area: 1.96 (0.15) m²

VO₂peak: 51 (8) ml/min/kg

Non-heat acclimatized

Duffield et al., 2010 [41]

Moderate to well trained cyclists of club and regional standard who trained multiple times a week, competing in regional competitions

Age: 24.8 (3.3) years

Height: 178.3 (8.0) cm

Body mass: 76.1 (2.7) kg

Sum of seven skinfolds: 54.4 (10.9) mm

Lactate threshold: 221 (42) W

Non-heat acclimatized

Gonzalez-Alonso et al., 1999 [40]*

Endurance trained

Age: 28 (3) years

Height: 187 (6) cm

Body mass: 77.9 (6.4) kg

HR_max: 200 (9) beats/min

VO₂peak: 5.13 (0.30) l/min

Non-heat acclimatized

Hasegawa et al., 2006 [43]*

Untrained

Age: 21.8 (0.8) years

Height: 1.72 (0.02) cm

Body mass: 61.7 (2.1) kg

Body fat: 15.1 (1.1) %

VO₂max: 48.5 (1.5) ml/kg/min

Non-heat acclimatized

Ihsan et al., 2010 [16]

Endurance trained regularly competing in cycling or triathlon, cycling more than four sessions and > 150 km/week

Age: 27.7 (3.1) years

Height: 176.7 (5.8) cm

Body mass: 81.38 (9.09) kg

Non-heat acclimatized

Kay et al., 1999 [28]*

Moderately to well-trained and undertook bicycle riding, training and competition on a regular basis

Age: 23.7 (2.1) years

Height: 182 (3) cm

Body mass: 76.1 (4.0) kg

Sum of four skinfolds: 28.4 (2.3) mm

Body surface area: 1.97 (0.06) m²

HR_max: 184 (3) beats/min

VO₂peak: 4.91 (0.25) l/min

Non-heat acclimatized

Quod et al., 2008 [27]

Well trained male cyclists with 6 (5) years of experience

Age: 28 (4) years

Height: 182 (2) cm

Body mass: 75.1 (3.2) kg

Sum of seven skinfolds: 50 (11) mm

VO₂peak: 71.4 (3.2) ml/kg/min

Maximum aerobic power: 384 (23) W

Non-heat acclimatized

Ross et al., 2011 [17]

Well trained A-grade cyclists aged 18 to 35 years

Age: 33 (5.1) years

Body mass: 72.1 (5.5) kg

Maximum aerobic power: 449 (26) W

VO₂peak: 71.6 (6.1) ml/kg/min

Heat acclimatized

Siegel et al., 2010 [18]

Moderately active, participating in recreational sport

Age: 28 (6) years

Height: 178.9 (6.3) cm

Body mass: 79.9 (11.2) kg

Sum of nine skinfolds: 92.8 (41.4) mm

VO₂peak: 56.4 (4.7) ml/kg/min

Non-heat acclimatized

Siegel et al., 2012 [19]

Moderately active, were partaking in recreational sport

Age: 26 (4) years

Height: 179.9 (6.7) cm

Body mass: 78.1 (5.9) kg

Sum of nine skinfolds: 87.3 (22.5) mm

VO₂peak: 54.2 (2.5) ml/kg/min

Non-heat acclimatized

Ückert and Joch, 2007 [26]

Regularly practiced types of sport with high endurance and strength components at a high level for example, soccer, athletics

Age: 25.6 (3.5) years

Height: 183.4 (7.6) cm

Weight: 77.9 (9.5) kg

Non-heat acclimatized