Table 7 Changes of haematological variables related to thermal acclimation protocols

Heat acclimation/acclimatisation

Costa et al. [50]

Runners (n = 6)

Three running exercise-heat exposures were performed at 30 °C (T1), followed by three running exercise-heat exposures at 35 °C (T2). Each running exercise-heat exposure was separated by 48 h

↓ (T1)

–

–

↓ (T1)

↑ + 7% (T1)

Loeppky [51]

Recreational athletes (n = 18)

PV variations were reported after 10 d of heat acclimation from studies in winter (WIN, n = 8) and summer (SUM, n = 10). In both studies, heat acclimation and dehydrating ergometer exercise were performed at 50 °C dry bulb and 26 °C wet bulb at 30% of each subject’s VO_2max

= ↓ − 2% (10 d)

–

–

=/= (10 d)

= ↑ + 5% (10 d)

Scoon et al. [52]

Runners (n = 6)

Six male distance runners completed 3 weeks of post-training sauna bathing and 3 weeks of control training with a 3-week washout. During the sauna period, subjects sat in a humid sauna at 90 °C immediately post-exercise for 30 min on 12 occasions

↓ − 1.3% (3 weeks)

–

–

↓ − 2% (3 weeks)

↑ + 7% (3 weeks)

Stanley et al. [53]

Cyclists (n = 7)

Seven well-trained male cyclists were monitored for 35 consecutive days (17 d baseline training, 10 d training plus sauna and 8 d training). Sauna exposure consisted of 30 min (87 °C, 11% relative humidity) immediately following normal training

↓ (4 d)

–

–

↓ (4 d)

↑ + 18% (4 d)

Tebeck et al. [54]

Cyclists (n = 11)

Eleven cyclists completed each of two 5-d blocks of short-term heat acclimation matched for heat index (44 °C) and total exposure time (480 min). The blocks were separated by 30 d. Two protocols were applied: dry (D/43 °C and 20% humidity) and humid (H/32 °C and 80% humidity)

↓/↓ (5 d)

–

–

↓/↓ (5 d)

↑ + 5%

↑ + 5% (5 d)

Oberholzer et al. [55]

Cyclists (n = 21)

Participants completed the 5½-week heat acclimation period, after which blood sampling was repeated. Blood sampling was conducted after 2 weeks into the intervention period prior to an exercise training session

= (NS)

= (NS) *Ret count

–

= (NS)

↑ + 7% (2 weeks)

Cold acclimation/acclimatisation

Banfi et al. [56]

Rugby players (n = 10)

Ten athletes were exposed daily to whole-body cryotherapy for 5 d at the Center of Spała, Poland. During this period, moderate training (3 h daily) continued for all athletes

↓ − 2% (5 d)

= (NS)

–

= (NS)

–

Checinska-Maciejewska et al. [57]

Swimmers (n = 34)

Thirty-four healthy subjects (18 men and 16 women) aged 50 years swam in cold seawater during the winter season at least twice a week. The average water temperature was 10 °C in October (T1), 1 °C in January (T2) and 4 °C at the end of April (T3)

↑ + 9% (T3)

–

–

= (NS)

–