Ratio between muscle fatigability and self-perceived tiredness could be an important parameter for characterizing frailty
Authors: V. Knoop, A. Costenoble, R. Vella Azzopardi, S. Vermeiren, A. Debain, B. Jansen, A. Scafoglieri and I. Bautmans
Publication Date: Feb. 2020
Purpose: Muscle fatigability is an important indicator of reduced intrinsic capacity, and therefore potentially an early characteristic of frailty. Meanwhile, self-perceived fatigue can be considered as a symptom of reduced intrinsic capacity. The aim of this study was to investigate whether older adults with low muscle fatigability and high feelings of fatigue are more prone to frailty.
Method: Four-hundred-and-four robust or pre-frail participants of the BUTTERFLY-study, a cohort study in well-functioning subjects aged 80+, were assessed for frailty score on Frailty Index of Fried (FFI), Groningen Frailty Indicator (GFI) and the Rockwood Index (RWI). Self-perceived fatigue was assessed by the Multidimensional Fatigue Index (MFI), muscle fatigability was measured with the Martin Vigorimeter, and expressed as grip work (GW = 0.75 * maximal grip strength * time for maximal grip strength to decrease to 50% during sustained contraction). Statistical analyses were corrected for age and sex.
Results: Pre-frail subjects showed significantly worse muscle fatigability and feel more fatigued than their robust counterparts (p<0.001). The ratio between muscle fatigability and self-perceived fatigue (GW/MFI) was significantly related to frailty (RWI (r=0,208), FFI (r=ǂ,228), GFI (r=ǂ,100)). This relationship was higher compared to independent correlations between MFI (r=0,186) and GW(r=0,202).
Conclusions: The ratio between muscle fatigability and self-perceived fatigue seems an interesting indicator for early frailty phenotypes, especially for physical frailty is the ratio an informative marker.