Recurrence quantification analysis of sustained sub-maximal grip contractions in patients with various metabolic muscle disorders

Recurrence quantification analysis (RQA)was used to analyse force signals during sustained sub-maximal grip contraction (SSGC) of three types of patients suffering from a metabolic muscle disorder (glycogen storage disease type III (GSD III), glycogen storage disease type V (GSD V) andmitochondrial myopathies (MITO)) compared to control subjects. Recurrence plots (RP) of patients showed clear non-uniformity, in comparison to control subjects who displayed quasi-periodic patterns. Quantitative analysis of the eywords: uscle contraction trength etabolic muscle disorders onlinear analysis RP showed significant differences between patients with metabolic disorders and the control group for four RQA parameters. The results showed that the SSGC signals of patients had decreased Lmax, which indicatedmore chaotic patterns. In addition the deterministic component of the signalswas less complex for patients than for controls. The differences of SSGC signal observed using RP and RQA were possibly related to the underlying changes in metabolism of muscle fibres due to the disease. Results of this study chniq haos theory ecurrence quantification illustrate that the RQA te