Faith F. Bradley1 , Grace S. Deetjen1, Michael J. Angelini2, Richard M. Kesler3, Matthew N. Petrucci4, Karl S. Rosengren5, Gavin P. Horn2,3, and Elizabeth T. Hsiao-Wecksler1,2

Exercise and Load Carriage Can Affect Firefighter Gait

1Dept. of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA 2 Dept. of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA

3Illinois Fire Service Institute, University of Illinois at Urbana-Champaign, Champaign, IL, USA 4Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL, USA

5Dept. of Psychology, Northwestern University, Evanston, IL, USA

Introduction • Slip, trip, and fall (STF) injuries account for over 11,000 fireground injuries

every year [1]. • Changes to gait have previously been associated with dynamic instability,

loss of control of gait, and muscular fatigue [2,3]. Muscular fatigue has been suggested to be an indicator of risk of STF injuries [4].

• This study quantified the effects of firefighter self-contained breathing apparatus (SCBA) design and duration of firefighting activities on gait parameters that may indicate risk for STF-related incidents.

Comparisons

Exercise Condition

Rounds Bout of exercise

1R 1

2R 2*

BB 2**

*5 minute rehabilitation break between bouts

outside chamber

**No break

Subjects completed 7 sessions with different combinations of SCBA and exercise durations.

Four comparisons testing: 1. SCBA size 2. Exercise 3. Profile 4. SCBA size * Exercise

P45

SCBA

Standard Cylinders Larger bottles supply more air but weigh more and create a larger displacement of the center of mass.

Low-Profile Prototype Designed to reduce displacement of center of mass. Comparable weight to S60 and comparable volume to S45.

S30 S45 S60

30-minute 45-minute 60-minute

P45

Firefighting-Simulating Exercise

Stair ascent and decent

Hose advance

Room search Ceiling pull

• Exercise completed in environmental chamber (47oC; 20% humidity, lights off)

• 1 Bout of exercise = 2 minutes each activity with 2 minutes rest between activities

P45_1R S45_1R

S60_BB

S60_2R S30_2R

S30_1R S60_1R

Methods Subjects • 30 Firefighters (29 male, 1 female) • Age: 30.7±8.1 years

• Height: 1.82±0.1 meters • Weight: 91.2±15.4 kilograms

Session Agenda

Gait Assessment (PRE) Exercise Protocol Gait Assessment (POST)

Gait Analysis

Results and Discussion SCBA Size

Multivariate ANOVAs were performed with SPSS (IBM, Armonk, NY) with significance levels of α=0.05 for all analyses. Values were averaged from two PRE and POST trials.

Results and Discussion (continued)

• Increased weight of SCBA increases DT. • Changes to double-support time suggests the S30 affects gait significantly less

than the S45 or S60. • Data represents average of PRE and POST. Error bars indicate standard error. • (*) indicates significant differences from S30_1R (p<0.05).

Conclusion • Heavier SCBA and extended duration of exercise may cause

firefighters to adopt more conservative gait, while profile appears to have no effect. These gait changes may serve as a compensatory strategy.

• The measured changes in gait may also indicate muscular fatigue, which has been previously suggested to be associated with an increased risk of STF injuries [3,4].

Future Work • Examine leg length, level of fitness and years of experience

interaction with SCBA and exercise duration on firefighter gait. • Examine if longer breaks will significantly reduce gait changes

resulting from fatigue. • Some firefighters were not able to complete each 2R or BB exercise

protocol. These data may be separated from those who fully completed all 8 sessions.

• All 4 gait parameters change as a result of an additional bout of exercise.

• No effects on gait parameters as a result of a rehabilitation break. • Reduced gait performance following an additional bout of exercise

may indicate greater muscular fatigue. • (*) indicates significant differences from S60_1R (p<0.05). • Data represents the average of PRE and POST values. Error bars

indicate standard error.

Exercise

Profile • No effects on gait with the low-profile prototype.

SCBA Size * Exercise • No significant interaction between the SCBA size and exercise.

Double-Support time (DT) = time both feet

contact ground

Four parameters of gait were assessed using a gait mat (GAITRite, 29 foot Platinum, CIR

Systems; Sparta, NJ): (1) stride velocity (SV)

(2) stride length(SL), (3) step width (SW) and (4) double-support time (DT).

7.92 m

[1] M. J. Karter, Patterns of Firefighter Fireground Injuries, Quincy, Massachusetts: National Fire Protection Association, 2003. [2] Barbieri, Fabio Augusto, et al. "Systematic review of the effects of fatigue on spatiotemporal gait parameters," Journal of back and musculoskeletal rehabilitation, 2013, 125-131. [3] Barbieri, Fabio Augusto, et al. "Effect of muscle fatigue and physical activity level in motor control of the gait of young adults." Gait & posture, 2013, 702-707. [4] Parijat, Prakriti, and Thurmon E. Lockhart. "Effects of lower extremity muscle fatigue on the outcomes of slip-induced falls." Ergonomics, 2008, 1873-1884.

References

Acknowledgements This project was funded through the DHS grant (#EMW-2010-FP-01606).