Influence of Lower Extremity Muscle Size and Quality on Stair-Climbing Performance in Career Firefighters

Research Team Members: Craig Kleinberg, Eric Ryan, Andrew Tweedell, TJ Barnette, and Chad Wagoner

firefightersWhy did you do this study?

Firefighters are a critical part of public safety and perform physically demanding jobs under hazardous conditions. In addition, firefighters must perform tasks, such as climbing stairs, dragging hoses, and forced entry while wearing personal protective equipment and their self-contained breathing apparatus weighing around 50 lbs.

Previous studies have demonstrated that muscle size and quality influences muscle strength and power. Thus, the purpose of this study was to determine if the size and quality of the quadriceps muscles is related to critical job tasks performed by firefighters. In this study, occupational performance was determined with a timed stair-climb assessment which is considered to be one of the most important job tasks among firefighters.

quadriceps-anatomyWhat did you do and what did you find in this study?

Using ultrasonography, we measured the size (cross-sectional area) and quality (muscle tissue composition and density) of the vastus lateralis and rectus femoris (2 muscles of the thigh) in 46 career firefighters.   Firefighters also performed a timed stair-climb test where they ascended and descended a flight of stairs 4 times (104 total steps) as quickly as possible. During the test, each firefighter wore a 50 lb vest to simulate the weight of their equipment. Our study demonstrated that both muscle size and quality were significant predictors of stair-climb performance in career firefighters.

How do these findings impact the public?

These findings suggest that lower extremity muscle size and quality may significantly influence one of the most demanding and critical firefighter tasks. Resistance training programs have recently been shown to improve both muscle size and quality and may serve as an important training strategy to improve occupational performance. However, given the high rate of injuries reported during exercise while on duty, certified strength and conditioning professionals are needed to help fire departments implement safe and effective resistance training programs.