Relationships Between Neuromuscular Function and Functional Balance Performance in Firefighters

Jacob A Mota,Brian Pietrosimone,Hayden K Giuliani,Timothy J Barnette,Gena R Gerstner,Craig R Kleinberg,Andrew J Tweedell,Brennan J Thompson,Eric D Ryan

doi:10.1038/s41598-018-33555-z

Abstract

The purpose of the present study was to examine the relationships between neuromuscular function and functional balance performance in firefighters. Fifty career firefighters (35.1 ± 7.5 yr) performed isometric leg extension and flexion muscle actions to examine peak torque (PT), and absolute (aTQ) and normalized (nTQ; %PT) rapid torque variables at 50, 100, 150, and 200 ms. A performance index (PI) was determined from the functional balance assessment completion time. Partial correlations were used to examine the relationship between the PI and the maximal and rapid TQ variables for each muscle and the composite value, while controlling for demographic data related to the PI. Multiple regression analyses examined the relative contributions of the maximal and rapid aTQ variables, and demographic data on the PI. After controlling for age and %BF, the majority of the later aTQ and nTQ variables (100–200 ms) and PT were associated with the PI (r = −0.501–−0.315). Age, %BF, and aTQ100 explained 42–50% of the variance in the PI. Lower rapid strength, increased age, and poorer body composition were related to worse performance during the functional balance assessment. Strategies to improve rapid strength and %BF, especially in aging firefighters may impact dynamic balance abilities in firefighters.

Highlights

Previous authors[10] have demonstrated that the leg flexors are more predictive of previous falls history than the leg extensors
Punakallio, et al.[18] demonstrated that functional balance assessments were predictive of decreased work ability in firefighters over a 3-year period. These assessments have been altered from their original form to include tasks that may be more commonly encountered on the fireground[13], and have been reported to be reliable[14] and sensitive to changes in firefighter personal protective equipment (PPE) and self-contained breathing apparatus (SCBA)[13,19]
Determining how maximal and rapid strength relates to functional balance performance may be important for identifying key impairments, which can be used to develop novel intervention strategies to mitigate the impact of STF in the fire service

Summary

Introduction

Previous authors[10] have demonstrated that the leg flexors are more predictive of previous falls history than the leg extensors. Punakallio, et al.[18] demonstrated that functional balance assessments were predictive of decreased work ability in firefighters over a 3-year period. These assessments have been altered from their original form to include tasks that may be more commonly encountered on the fireground[13], and have been reported to be reliable[14] and sensitive to changes in firefighter personal protective equipment (PPE) and self-contained breathing apparatus (SCBA)[13,19]. The purpose of the present study was to examine the relationships between maximal and rapid strength and functional balance performance in career firefighters. Based upon previous literature[9,10,11,20], we hypothesized that leg flexion rapid strength at early time intervals (i.e. 50 ms) would be the variable most strongly associated with functional balance performance

Objectives

Methods

Results

Conclusion