Variations in serum myoglobin after a 2-min isokinetic exercise test and the effects of training.

Serum-myoglobin was measured after the completion of three different types of exercise i.e., dynamic, isometric, and isokinetic. The maximal rises in serum-myoglobin levels were 20%, 70%, and 300%, respectively. On the basis of this finding a 2-min isokinetic test was developed and standardized for the purpose of studying conditions in vivo that may affect myoglobin leakage from skeletal muscle cells. Fourteen healthy men performed the 2-min isokinetic test. Blood lactate increased on average eight times with maximal levels obtained 4 min after completed work. S-Myoglobin levels obtained 4 min after completed work. S-Myoglobin was raised approximately five times after 2 h. The rise in S-myoglobin was significantly (P less than 0.01) related to the loss in muscle strength (torque decline) during the test. After a training period of 3 weeks comprising 4 min of maximal isokinetic exercise three times a week the rise in S-myoglobin after a 2-min isokinetic test was reduced from on average 240 micrograms X 1(-1) to 96 micrograms X 1(-1) (P less than 0.001). The rise in blood lactate was not related to the variations in S-myoglobin or affected by training. The 2-min isokinetic exercise test is an easily standardized exercise test which in combination with measurements of serum-myoglobin should prove valuable in the study of conditions affecting leakage from muscle cells.