Response of serum enzymes and other biochemical constituents to strenuous exercise in control subjects and patients with motor neurone disease

Abstract

Serum enzymes were estimated in 10 patients with motor neurone disease (MND) and in 5 control subjects at rest and after strenuous exercise. Creatine phosphokinase (CPK) levels were abnormally increased at rest in 6 of the MND patients, 1 of whom had the only abnormal increase in resting level of malate dehydrogenase (MDH). MDH and CPK increased, sometimes to abnormal levels, in response to exercise in control subjects. The mean rise in MDH after exercise in the MND patients closely paralleled that of the control group. In spite of higher resting CPK levels in MND patients compared to controls, the percentage increase in CPK activity immediately after exercise in this group was significantly lower than for controls. No significant changes in aspartate aminotransferase (GOT), sodium, total protein or urea were observed in either group before or after exercise, but significant differences were noted in the response patterns of potassium and bicarbonate. We suggest that abnormal resting CPK activities recorded in MND patients are caused by near maximal efflux from actively necrotic muscle cells, and any superimposed rise in CPK levels after exercise may be contributed by enzyme efflux from the remaining normal muscle cell mass.