Year of Award


Document Type


Degree Type

Master of Science (MS)

Degree Name

Health and Human Performance (Exercise Science Option)

Department or School/College

Integrative Physiology and Athletic Training

Committee Chair

Dr. Charles Dumke

Commitee Members

Dr. John Quindry Dr. Charles Palmer Joseph Sol


wildland firefighting, DOMS, creatine kinase, overtraining, preparedness, occupational physiology


University of Montana

Subject Categories

Exercise Physiology | Exercise Science | Systems and Integrative Physiology


Introduction: Wildland firefighters (WLFF) undergo a critical training (CT) period immediately before the firefighting season. The intensity of CT exercise could lead to muscle damage, as previously reported cases of rhabdomyolysis in WLFFs have been documented. This study established the effects of activities performed during a two-week CT period on acute markers of muscle damage in WLFFs.

Methods: 18 male and 3 female Type I Interagency Hotshot WLFFs were studied during a 14-day critical training period. Upper- (US) and lower-body (LS) muscle soreness and daily body weight (BW) scales were collected. Venous blood was collected on Days 1, 4, 8, and 11 to measure markers of muscle damage (creatine kinase, lactate dehydrogenase, c-reactive protein) and overtraining (cortisol, testosterone). Skinfold measurements were taken on Days 1 and 11 to calculate body fat (BF) and lean body weight (LBW). The BLM fitness challenge defined fitness.

Results: No differences in body weight were observed Days 1-11 (p=0.065). BF significantly decreased from Day 1 to 11 (15.3±1.4% vs. 14.1±1.3%, p=0.002), while LBM significantly increased (67.3±2.3kg vs. 68.8±2.2kg, p=0.002). US and LS showed main effects of time, elevated from baseline for subsequent days, peaking on Day 3 (US: 3.8±0.5 cm, p<0.001; LS: 4.3±0.3 cm, p<0.001). CK showed a significant effect of time, elevated from baseline, peaking on Day 4 (73.4±14.4 U·L-1vs. 132.8±15.4 U·L-1, p=0.001). LDH showed a significant effect of time, where Day 11 significantly increased from Day 1 (159.4±5.5 IU·L-1 vs.164.4±6.9 IU·L-1, p=0.04). There was no significant difference in CRP (p=0.32). There was a significant increase in cortisol on Day 8 (48.0±4.6 ng·mL-1 vs. 61.9±2.9 ng·mL-1, p=0.036), while no difference was seen in testosterone (p=0.25). The testosterone/cortisol ratio showed a significant decrease on Day 8 (0.31±0.05 vs. 0.19±0.02, p=0.014). Elevated fitness and off-season training habits correlated with ameliorations in these markers.

Conclusion: These data suggest that WLFFs undergo significant physiological stressors resulting in muscle soreness, damage, and overtraining during CT. Fitness and preparedness appear to have a protective effect on the strain experienced from the training stimulus. Careful preparation and monitoring of the training stimulus are vital to avoid clinical ramifications.



© Copyright 2020 Katherine Sue Christison