Muscle quality, architecture, and activation in cachectic patients with rheumatoid arthritis.
OBJECTIVE
To explore muscle-specific force (force per physiological cross-sectional area, or PCSA) and muscle activation in cachectic patients with rheumatoid arthritis (RA).


METHODS
In 14 muscle-wasted patients with RA and age and sex matched healthy controls, vastus lateralis (VL) force and voluntary activation capacity were assessed during maximal isometric contractions with electromyography and superimposed electrical stimulations. VL PCSA was determined from ultrasound measures of fiber fascicle length (Lf), pennation angle, and volume, together with assessments of body composition by dual energy x-ray absorptiometry and objective physical function.


RESULTS
Although patients with RA had reduced physical function, lower muscle mass, and VL volume relative to controls, there were no differences in muscle-specific force and activation. PCSA, force, and pennation angle tended to be lower in RA, with no differences in Lf.


CONCLUSIONS
Muscle-specific force and activation are not compromised and thus are unlikely to contribute to reduced function in cachectic patients with RA.
Matschke
Verena
V
School of Sport, Health and Exercise Sciences, Bangor University, George Building, Gwynedd, UK. v.matschke@bangor.ac.uk
Murphy
Peter
P
Lemmey
Andrew B
AB
Maddison
Peter J
PJ
Thom
Jeanette M
JM
D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000150:complications / Q000473:pathology / Q000503:physiopathology*; D002100:Cachexia / Q000209:etiology / Q000473:pathology / Q000503:physiopathology*; D004558:Electric Stimulation; D004576:Electromyography; D005260:Female; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D018485:Muscle Fibers, Skeletal / Q000473:pathology; D010807:Physical Endurance; D052097:Quadriceps Muscle / Q000473:pathology / Q000503:physiopathology*; D012720:Severity of Illness Index