[Studies on the serum aldolase activity in workers with muscle disorders caused by vibration work]

Recently, vibrating tools such as chain saws, pneumatic hammers, rock drills, riveters, and grinders have been widely introduced in various industries in order to increase efficiency and to reduce the burden of labor. The disease due to hand-arm vibration often causes serious damages to the operator's body, more particularly of the circulatory, peripheral nervous, osteo-articular and muscular systems. Many kinds of examinations such as roentgenography, electromyography, and sthenometry have been used to diagnose the damage to the musculoskeletal systems. Among these, the measurement of muscular strength, evaluated by grip and pinch strength, is widely used in mass examinations of vibration hazards but this is not always effective in precise recognition of the decrease in muscular strength. In the present study, therefore, in order to diagnose the severity of muscle disorders objectively, serum activities of aldolase (ALD), creatine phosphokinase (CPK) and lactate dehydrogenase (LDH), which are called "muscle enzymes," were determined in 260 chain saw operators aged 40 to 59 years. The same tests were performed for 46 healthy subjects (controls) of a similar age-range, who had a very short experience handling bush cleaners. All chain saw operators were classified into four groups according to the total chain saw operating time (TOT): 1) 58 operators with up to 2,500 hours' experience, 2) 70 with 2,500-5,000 hours' experience, 3) 74 with 5,000-10,000 hours' experience, and 4) 58 with over 10,000 hours' experience. The relationships were investigated in their enzyme activities on the one hand, and their TOT, muscular strength and numbness and pain symptoms related to muscle disorders of the upper extremities on the other hand. The following results were obtained: 1) Serum ALD and LDH activities in chain saw operators increased in proportion to the decrease in muscular strength. The activity of ALD showed a tendency to increase with increased TOT. The ALD activity in the group with over 5,000 hours' experience was significantly higher than that in the control group. However, no relationships were observed between CPK, LDH activities and TOT. 2) In chain saw operators with numbness and pain symptoms, ALD activity in the group with 2,500 hours' experience was significantly higher than that in the control group. However, no obvious relationships were found between CPK, LDH activities and numbness and pain symptoms. 3) In chain saw operators with muscular weakness in addition to numbness and pain symptoms, ALD activity in the group with over 2,500 hours' experience was significantly higher than that in the control group.(ABSTRACT TRUNCATED AT 400 WORDS)