Functional Performance of Firefighters After Exposure to Environmental Conditions and Exercise.

CONTEXT: Slips, trips, and falls are leading causes of musculoskeletal injuries in firefighters. Researchers have hypothesized that heat stress is the major contributing factor to these fireground injuries. OBJECTIVE: To examine the effect of environmental conditions, including hot and ambient temperatures, and exercise on functional and physiological outcome measures, including balance, rectal temperature, and perceived exertion. DESIGN: Randomized controlled clinical trial. SETTING: Laboratory environmental chamber. PATIENTS OR OTHER PARTICIPANTS: A total of 13 healthy, active career firefighters (age = 26 ± 6 years [range = 19-35 years], height = 178.61 ± 4.93 cm, mass = 86.56 ± 16.13 kg). INTERVENTION(S): Independent variables consisted of 3 conditions (exercise in heat [37.41°C], standing in heat [37.56°C], and exercise in ambient temperature [14.24°C]) and 3 data-collection times (preintervention, postintervention, and postrecovery). Each condition was separated from the others by at least 1 week and lasted a maximum of 40 minutes or until the participant reached volitional fatigue or a rectal temperature of 40.0°C. MAIN OUTCOME MEASURE(S): Firefighting-specific functional balance performance index, rectal temperature, and rating of perceived exertion. RESULTS: Exercise in the heat decreased functional balance, increased rectal temperature, and altered the perception of exertion compared with the other intervention conditions. CONCLUSIONS: A bout of exercise in a hot, humid environment increased rectal temperature in a similar way to that reported in the physically active population and negatively affected measures of functional balance. Rather than independently affecting balance, the factors of exercise and heat stress appeared to combine, leading to an increased likelihood of slips, trips, and falls.

Impact of Protein and Carbohydrate Supplementation on Musculoskeletal Injuries in Army Initial Entry Training Soldiers.

This project investigated whey protein and/or carbohydrate supplementation effects on musculoskeletal injury (MSI) outcomes. Four groups of Initial Entry Training soldiers consumed either: (1) one protein (38.6 g, 293 kcal); (2) one carbohydrate (63.4 g, 291 kcal); (3) two protein (77.2 g, 586 kcal); or (4) two carbohydrate servings/day (126.8 g, 582 kcal) after physical training and before bed, or before bed only. Odds Ratio, Chi-square and Wilcoxon ranked-sum test compared supplementation/no supplementation, number of servings, and protein/carbohydrate for MSI and limited/missed duty rates and limited/missed training days. Non-matched pairs group averages were compared to 2015/2016 historical data. Non-supplemented soldiers were approximately 5× more likely to sustain a MSI (χ2 = 58.48, p < 0.001) and 4× more likely to miss training (χ2 = 9.73, p = 0.003) compared to two servings. Non-supplemented soldiers missed five additional training days compared to two servings (W = 6059.5, p = 0.02). Soldiers consuming one serving were approximately 3× more likely to sustain a MSI than two servings (χ2 = 9.55, p = 0.002). There was no difference in limited/missed duty rates or limited/missed training days between consuming one or two servings. There was no difference between consuming one serving versus no supplementation or protein versus carbohydrate supplementation for any outcome variable. Soldiers consuming 2 servings/day of protein or carbohydrate had lower MSI rates, limited/missed duty rates, and limited/ missed training days compared to non-supplemented soldiers.

Effect of Whey Protein Supplementation on Physical Performance and Body Composition in Army Initial Entry Training Soldiers.

We investigated the effects of whey protein (WP) supplementation on body composition and physical performance in soldiers participating in Army Initial Entry Training (IET). Sixty-nine, male United States Army soldiers volunteered for supplementation with either twice daily whey protein (WP, 77 g/day protein, ~580 kcal/day; n = 34, age = 19 ± 1 year, height = 173 ± 6 cm, weight = 73.4 ± 12.7 kg) or energy-matched carbohydrate (CHO) drinks (CHO, 127 g/day carbohydrate, ~580 kcal/day; n = 35, age = 19 ± 1 year, height = 173 ± 5 cm, weight = 72.3 ± 10.9 kg) for eight weeks during IET. Physical performance was evaluated using the Army Physical Fitness Test during weeks two and eight. Body composition was assessed using 7-site skinfold assessment during weeks one and nine. Post-testing push-up performance averaged 7 repetitions higher in the WP compared to the CHO group (F = 10.1, p < 0.001) when controlling for baseline. There was a significant decrease in fat mass at post-training (F = 4.63, p = 0.04), but no significant change in run performance (F = 3.50, p = 0.065) or fat-free mass (F = 0.70, p = 0.41). Effect sizes for fat-free mass gains were large for both the WP (Cohen's d = 0.44) and CHO (Cohen's d = 0.42) groups. WP had a large effect on fat mass (FM) loss (Cohen's d = -0.67), while CHO had a medium effect (Cohen's d = -0.40). Twice daily supplementation with WP improved push-up performance and potentiated reductions in fat mass during IET training in comparison to CHO supplementation.