Table 2.
Key data, findings and critical appraisal scores (CAS) and methodological quality ratings of included articles
| Study | Participants | Outcome measure(s) | Intervention(s) | Major Findings | CAS (%) |
|---|---|---|---|---|---|
| Cuddy et al. [1] | 15 Hot Spot firefighters (12 male, 3 female) Wore PPE |
Water turnover Nude BW |
Live wildland fire suppression over 3 days of work shifts (11.4 ± 0.7 h/day) (hiking, line dragging, laying hose, chain sawing, clearing brush, lookout, and scouting) Ad libitum drinking 27.5 ± 3.2 °C mean ambient temperature |
No significant change (p = 0.12) in morning BW across 3 days (pre 77.3 ± 8.3 kg, post 77.0 ± 8.9 kg) Mean water turnover 9.5 ± 1.7 L/d |
54 (Fair) |
| Raines et al. [2] | 32 firefighters (31 male,1 female) Ad libitum(AD) group (n = 17), pre-shift (PR) group (n = 15) PPE |
Plasma Osm Urine colour USG |
PR group consumed 500 mL fluid bolus pre shift and ad libitum remainder of shift 7 days (9.9 ± 2.2 h/day AD, 9.7 ± 2.3 h/day PR) of wildfire suppression (intense but intermittent work, using chainsaws, applying water, carrying, transit time and briefings) Mild to warm ambient temperatures (15.8–26.4 °C) |
No difference between groups in total fluid intake (3.4 ± 1.6 L AD, 3.7 ± 2.9 L PR, p = 0.730) No significant differences between groups for any hydration marker (urine colour, p = 0.44; USG, p = 0.92; plasma Osm, p = 0.41) Significant decrease in both urine colour (p = 0.001) and USG (p = 0.01) across the shift, but still dehydrated by end, though less than at start Plasma Osm indicates firefighters arrived on shift dehydrated and finish dehydrated (p < 0.0001) |
57 (Fair) |
| Horn et al. [6] | 35 career, volunteer and industrial firefighters (31 male, 4 female) Wore PPE and SCBA |
Nude BW Urine colour USG Urine Osm Salivary Osm |
3 h live fire training exercise in specialised training building. 3–4 evolutions lasting 15–25 min, separated by 10–15 min (obtain water, advance hoses, extinguish fires, forcible entries, search and rescue and ventilation tasks) Encouraged ad libitum drinking (water and sport drink) Cool autumn day |
Significant BW loss of 1.1 ± 0.8 kg (p < 0.001) and 1.9 ± 0.9 kg (2.2 % BW loss) adjusted for fluid intake and voiding Significant (p < 0.001) increase in salivary Osm (pre 78.0 ± 21.5 mOsm/kg, post 49.0 ± 15 mOsm/kg), reflective of dehydration No significant (p > 0.05) changes in Urine Osm (pre 768 ± 260 mOsm/kg, post 712 ± 251 mOsm/kg), urine colour (pre score 5.8 ± 1.5, post score 5.3 ± 1.5), or USG (pre 1.025 ± 0.009, post 1.024 ± 0.009) |
61 (Good) |
| Holsworth et al. [7] | 9 volunteer firefighters (8 males, 1 female) WorePPE and SCBA |
HCT | 2 × 30 min strenuous live structural fires No fluid intake |
Significant (p = 0.0014) change in HCT (pre 43.7 ± 3.1 %, post 46.1 ± 2.3 %), indicating significant dehydration | 61 (Good) |
| Smith et al. [8] | 11 male professional firefighters WorePPE and SCBA (20.4 kg) |
HCT | 3 trials of 5 standardised firefighting drills in a training structure (carrying a hose up 4 flights, hoisting a hose, discharging a pump can, dragging a dummy, chopping a block of wood). 10 min rest between trials No fluid intake Unknown ambient temperature |
Significant (p < 0.001) change in HCT (pre 43.2 ± 0.75 %, post 47.3 ± 0.75 %), indicating significant dehydration | 57 (Fair) |
| Angerer et al. [9] | 49 firefighter trainees (all male) Wore PPE and SCBA (24 kg) |
Nude BW | 30 min fire operation in a large simulation plant (ascending stairs, dragging hoses, fire suppression, dragging 80 kg dummy up and downstairs, crouched progression) No fluid intake Maximum 200 °C at 1.5 m above ground and 700 °C below the ceiling |
BW significantly (p <0.001) reduced by mean 0.6 ± 0.2 kg | 61 (Good) |
| Raines et al. [12] | 34 firefighters (32 male, 2 female) AD group (n = 17) PR group (n = 17) Wore PPE |
Plasma Osm Urine colour USG |
PR group consumed 600mLwater and 600 mL sport drink per hour of shift One day (9.9 ± 2.2 h/day AD, 10.5 ± 2.2 h/day PR) of wildfire suppression (intense but intermittent work, using chainsaws, applying water, carrying, transit time and briefings) Mild to warm ambient temperature (15.8–26.4 °C) |
PR group significantly higher total water intake (7.1 ± 3.1 L PR, 3.4 ± 1.6 L AD, p < 0.001) Both groups began work dehydrated according to USG (1.019 ± 0.007 AD, 1.016 ± 0.005 PR) PR post shift had significantly (p = 0.001) lower USG (1.004 ± 0.002) than AD (1.016 ± 0.008) Change from dehydrated to euhydrated for PR group only Significant (p < 0.01) change in urine colour for both groups (pre score 2.8 ± 0.4 AD, 2.6 ± 0.5 PR, post score 2.3 ± 0.8 AD, 1.4 ± 0.5 PR), but still dehydrated Plasma Osm no different between groups (p = 0.371), both arrived dehydrated and post shift both significantly reduced (p < 0.0001) to achieve similar euhydration |
57 (Fair) |
| Ruby et al. [15] | 14 wildland firefighters Wore PPE |
Water turnover USG Urine Osm |
5 day period of arduous fire suppression (hiking with load and fire line construction) Ad libitum drinking Unspecified ambient temperature |
Water turnover 6.7 ± 4 L/day No significant change in USG (pre 1.016 ± 0.006, post 1.108 ± 0.006) No significant change in urine Osm (pre 562 ± 175 mOsm/L, post 629 ± 216 mOsm/L) |
50 (Fair) |
| Raines et al. [18] | 12 male wildfire firefighters Wore PPE |
Plasma Osm | 2 days of 12 h live fire prescribed operation (controlled fire application, building containment lines with hoe, chasing spot fires and applying water) Ad libitum drinking Hot ambient temperature (30.9 ± 3.6 °C day 1, 32.8 ± 5.7 °C day 2) |
No significant (p = 0.73) change in plasma osmolality (day 1 292 ± 1 mOsm/L, day 2 289 ± 0.5 mOsm/L), indicating euhydration throughout | 57 (Fair) |
| Eglin et al. [28] | 14 firefighter instructors (all male) Wore PPE and SCBA (20.2 kg) |
USG Nude BW (adjusted) Fluid deficit |
30 hot fire (HF) exercises (33 ± 7.9 min, 74 ± 42 °C) 6 fire behaviour (FB) exercises (26.3 ± 5.5 min, 45 ± 12 °C) and 8 fire attack (FA) exercises (7.3 ± 2.6 min, 139 ± 48 °C) performed on same day with 2 h rest in-between Ad libitum drinking |
Mean BW change 0.96 ± 0.41 kg/h, fluid deficit 0.62 ± 0.61 L HF exercises (0.79 ± 0.80 %/h) Mean BW change 1.59 ± 0.57 kg for FB and FA exercises Mild hypohydration at end of exercises with insufficient fluid intake to counteract body weight loss from sweating No significant (p > 0.05) change in USG (pre 1.019 ± 0.08, post 1.021 ± 0.009) |
50 (Fair) |
CAS critical appraisal score, PPE personal protective equipment, SCBA self-contained breathing apparatus, HCT haematocrit, USG urine specific gravity, BW body weight, Osm osmolality