October 2012

Testing muscle tone and mechanical properties of rectus femoris and biceps femoris using a novel hand held MyotonPRO device: relative ratios and reliability

Authors: J. Mullix, M. Warner, M. Stokes

Affiliations: Faculty of Health Sciences, University of Southampton, United Kingdom

Journal: Working Papers in Health Sciences - October 2012 (ISSN: 2051-6266 / 20120006)

To use a novel, non-invasive hand held device (MyotonPRO) to quantify ratios of relative non-neural tone and
mechanical properties of the rectus femoris (RF) and biceps femoris (BF) muscles, and to assess reliability of a novice user.

The device offers rapid, objective testing of mechanical parameters of muscle in clinical or sports settings.

Participants: 21 healthy males (20-35 years)

Relaxed muscle parameters of RF and BFwere obtained using the MyotonPRO. The device applies a brief mechanical
impact, producing muscle oscillations from which tone (state of intrinsic tension, indicated by frequency [Hz]) and mechanical properties of elasticity (logarithmic decrement) and stiffness (N/m) are measured. Data were collected on two days, one week apart. Two series of 10 single measurements on each muscle were used to test within-day reliability. The mean of the two sets was used for between-day reliability.

The relative parameters between RF and BF were expressed as a ratio. Reliability was assessed using intra-class
correlation coefficients (ICCs).

The mean (±SD) RF:BF ratios for resting muscle were: frequency 1:0.96 (±0.05), decrement 1:1.10 (±0.17) and stiffness
1:0.95 (±0.07). Reliability of all three parameters was excellent within-sessions (ICCs 3,2 >0.99) and good between-days (ICCs 3,1 0.72-0.87).

The relative resting tone and mechanical properties of RF and BF has been characterised in young males, with
ratios close to 1:1. Measures made by a novice user were reliable, indicating that the MyotonPRO has the potential for
assessing changes in muscle properties objectively over time. Studies are needed in large healthy cohorts of different ages, activity levels and genders to produce reference data for assessing patients.

Implications: The relative tone and mechanical properties of RF and BF could potentially be used as a rapid method for
assessing risk of injury is sporting populations and presence of abnormality in musculoskeletal and neurological conditions, once normal values have been established in relevant groups.