Modified exercise test in screening for mitochondrial myopathies--adjustment of workload in relation to muscle strength.
The aim of this study was to evaluate the usefulness of a modification of the bicycle ergometer test, the subanaerobic threshold exercise test (SATET), as a screening test for patients with mitochondrial myopathies. Since the original SATET is frequently found to be strenuous for weak patients, a new variable (relative muscle strength) was added to the workload formula. Plasma lactate levels were recorded at rest, then after 5 and 15 min of cycling on an ergometer, with constant workload. Nine patients with mitochondrial myopathy, 10 patients with other neuromuscular diseases and 9 healthy but sedentary volunteers undertook the test. An upper reference limit after exercise for plasma lactate was settled at 2.9 mmol/l. The modified SATET showed a sensitivity of 78% and a specificity compared to the healthy subjects of 100%. Compared to patients with other neuromuscular diseases, the specificity was lower (60%). All subjects completed the test without severe fatigue or pain.
Hammarén
Elisabet
E
Neuromuscular Centre, Department of Neurology, Sahlgrenska University Hospital, Mölndal, Sweden. elisabet.hammaren@vgregion.se
Rafsten
Lena
L
Kreuter
Margareta
M
Lindberg
Christopher
C
D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D005080:Exercise Test / Q000379:methods; D017079:Exercise Tolerance; D005260:Female; D006801:Humans; D019344:Lactic Acid / Q000097:blood*; D008297:Male; D008403:Mass Screening / Q000379:methods*; D008875:Middle Aged; D017240:Mitochondrial Myopathies / Q000097:blood / Q000175:diagnosis*; D018482:Muscle, Skeletal / Q000503:physiopathology*; D009468:Neuromuscular Diseases / Q000175:diagnosis; D012680:Sensitivity and Specificity
D019344:Lactic Acid