Relationships between Height, Mass, Body Mass Index, and Trunk Muscle Activation during Seated Whole-Body Vibration Exposure

Marwan Hassan,Michele Oliver,Alexander Nolan,Megan Govers

doi:10.3390/vibration4040046

Abstract

Operators of heavy equipment are often exposed to high levels of whole-body vibration (WBV), which has been associated with a variety of adverse health outcomes. Although anthropometric factors are known to impact vibration dose and risk of low back pain, studies have yet to investigate the influence of anthropometric factors on muscle activation during WBV exposure. This study quantified the relationships between muscle activation, vibration frequency, body mass, body mass index (BMI), and height both pre- and post-fatigue. Muscle activation of the external oblique (EO), internal oblique (IO), lumbar erector spinae (LE) and thoracic erector spinae (TE) were quantified using surface electromyography. Results indicate increased activation with increased mass, BMI, and frequency for the LE, TE, and IO, which may be a result of increased activation to stabilize the spine. Decreased muscle activation with increased height was seen in the TE, IO, and pre-fatigue EO, which could indicate higher risk for low back injury since height is associated with increased forces on the spine. This may contribute to the association between increased low back pain incidence and increased height. Results suggest that ISO 2631-1 health guidance should incorporate anthropometric factors, as these may influence muscle activation and back injury risk.

Highlights

Introductionwhole-body vibration (WBV) has been related to a variety of adverse health outcomes including degenerative changes in the spine [6,7], low back pain [7,8,9] and sciatic nerve pain [7,9]
Muscle activation and vibration frequency were positively correlated for pre-fatigue transformed %maximum voluntaryvoluntary electrical electrical activationactivatio activation (MVE) data (%MVET ) of the internal oblique (IO) (ρ = 0.25, p < 0.0001), lumbar erector spinae (LE) (ρ = 0.17, p < 0.0001), and thoracic erector spinae (TE) (ρ = 0.17, p < 0.0001), but negatively correlated in the external oblique (EO) (ρ = −0.16, p < 0.0001)
The results indicate increased muscle activation in individuals with increased body mass and body mass index (BMI) in all the trunk muscle groups investigated (EO, IO, LE, TE), as well as decreased muscle activation with increased height in the IO and TE, as well as the EO post-fatigue

Summary

Introduction

WBV has been related to a variety of adverse health outcomes including degenerative changes in the spine [6,7], low back pain [7,8,9] and sciatic nerve pain [7,9]. ISO 2631-1 provides health guidance zones for vibration exposure. ISO 2631-1 provides health weightings that are used to determine RMS (root mean square) values of frequency weighted acceleration [13]. Once the RMS acceleration values have been determined, they can be compared to the health guidance caution zones, assuming exposure times of

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