Surface electromyography assessment of muscle activation patterns while sitting down in young healthy women and patients with ankylosing spondylitis [Povrchové elektromyografické hodnocení svalové aktivity ve zkou ce posazení u zdravych mladych en a u pacient s ankylozující spondylitidou]

BACKGROUND: Muscle activation patterns depend on many factors. Surface electromyography (SEMG) can reveal these patterns in subjects of different ages and health states. We studied patterns of muscle activation in two groups of subjects - healthy young women (as a control group) and patients with ankylosing spondylitis. OBJECTIVE: The aim of this study was to register and compare muscle activation patterns while sitting down in these two groups in four situations with different positions of the lower and upper limbs. METHODS: Muscle activity was registered with the use of 8 channel surface polyelectromyography (Noraxon-Myosystem 1400A). We tested the following muscles bilaterally while the subjects were sitting down (tibialis anterior muscle, medial head of the gastrocnemius muscle, gluteus maximus muscle, erectores spinae muscles). The onset of each individual muscle's activity was determined by calculating the sum of the mean value of the SEMG baseline plus 10% of the maximum value of amplitude (peak). RESULTS: It was registered that the medial head of the gastrocnemius muscle and/or erectores spinae muscles were activated as the first ones in both groups of the subjects under study in most of the studied postural situations. We registered differences in timing (sequence of muscle activation) among various studied body and limb positions (P–, P+, PD–, and PN–). A great degree of variability in the sequence of muscle activation was revealed, depending on the positions of the upper and lower limbs. CONCLUSIONS: We did not find any unique patterns of muscle activation in either of the two groups under study. [VYCHODISKA: asové zapojování (aktivace) sval je závislé na mnoha faktorech. Povrchová polyelektromyografie zachycuje vzorce zapojování sval u proband rozdílného věku a zdravotního stavu v r znych podmínkách. CíLE: Cílem studie byla registrace a hodnocení po adí zapojování sval v pr běhu sedání u těchto dvou skupin en ve ty ech situacích s rozdílnymi pozicemi horních i dolních kon etin. METODIKA: Studovali jsme po adí zapojování sval u dvou skupin en – zdravych mladych en (jako kontrolní skupiny) a pacient s ankylozující spondylitidou. Aktivace vybranych sval byla hodnocena povrchovou polyelektromyografií (Noraxon-MyoSystem 1400A). Elektrody byly umístěny nad ty i vybrané svaly bilaterálně (m. tibialis anterior, mediální hlava m. gastrocnemii, m. gluteus maximus a mm. erectores spinae). Pro zji tění okam iku nástupu zapojení sval (timing) jsme pou ívali klidovou hodnotu amplitudy EMG signálu plus 10 % maximální hodnoty amplitudy (peak).