Increased serum enzyme activity after exercise was first reported in 1958; subsequent studies have established that many factors determine the degree to which the serum activities of a variety of enzymes increase during and after exercise. The serum activities of those enzymes found especially in muscle, particularly creatine kinase, increase in proportion to the intensity and duration of the preceding exercise, peaking 24 hours after exercise; the effect of duration is dominant, so that the highest postexercise serum enzyme activities are found after very prolonged competitive exercise such as ultradistance marathon running or triathlon events. Weight-bearing exercises which include eccentric muscular contractions such as bench stepping and downhill running induce the greatest increases in serum enzyme activities; serum enzyme activities increase very little even after prolonged participation in those non-weight-bearing activities such as swimming and cycling which do not include eccentric muscular contractions. Prolonged (greater than 2 hours) daily training or competition in weight-bearing activities produces chronically elevated serum enzyme activities. Serum enzyme activities increase more with exercise in males, Blacks and the untrained than they do in females, Whites and the trained, respectively; age does not appear to influence the degree to which serum enzyme activities increase with exercise. There is a remarkable individual variability in the degree to which serum enzyme activities increase with exercise; a 50-fold difference in post-race serum creatine kinase activities has been found in healthy and equally trained athletes completing the same 90km ultramarathon footrace. The biochemical explanation for this degree of individual variability is not currently understood; possibly persons who show abnormally large increases in serum enzyme activities with exercise may have as yet unrecognised subclinical myopathies. No circadian rhythms have been identified for serum enzyme activities; activities rise during the day because of increased physical activity. The rise in serum enzyme activities is greater after exercise at altitude or in the heat than after equivalent exercise at sea level or in the cold. The most likely explanation for the increased serum enzyme activities that follow prolonged weight-bearing activities that also cause marked muscle soreness, is myofibrillar damage in particular sarcomeric Z-disk disruption.(ABSTRACT TRUNCATED AT 400 WORDS)

Effect of exercise on serum enzyme activities in humans.

In 18 groups of trained healthy male subjects (n=166; age 17–42 years) the influence of type and duration of long-lasting exercise on the changes of creatine kinase (CPK) and hexose phosphate isomerase (PHI) activity in serum was studied. Above 65–70% of maximal aerobic capacity, a serum enzyme activity increase proportional to the exercise time was found with a different slope in each of the three exercise types examined [a) bicycle ergometer; b) ski race; c) impact-type exertion]. Work duration of more than 300 min induced in the third type of exertion an accelerated increase in serum CPK. A third degree equation best describes the changes in serum CPK for nine of our groups and five others from the literature. To ascertain the possible influence of intravascular hemolysis, sera were mixed with autologous erythrocyte hemolysates and enzyme activity measured. The findings are discussed with reference to critical aspects of the analytical methods, possible causes of serum enzyme changes, and possible use of enzyme measurements in evaluating adaptation of the organism to prolonged exercise.

Changes in serum creatine kinase and hexose phosphate isomerase activity with exercise duration

A number of blood biochemical parameters, including the activities of the plasma enzymes creatine kinase (CK), aspartate aminotransferase (ASAT), lactate dehydrogenase and alkaline phosphatase, were measured in 23 athletes before, and immediately after a 56-km running race. Of the 23 athletes, 18 had previously completed standard 42-km marathon or longer (up to 90-km) ultra-marathon races, whereas not one of the other five athletes had previously run in a long-distance race. After the race, plasma CK and ASAT activities had both risen at least 280% more in the novice runners despite their much slower mean running speed (9.8 +/- 0.4 vs. 13.8 +/- 0.3 hm/h). There were no other inter-group differences in the absolute levels of the other measured biochemical parameters, although the rise in plasma calcium during the race was significantly greater in the experienced marathon runners. This study shows that either higher levels of training, or previous ultra-marathon racing experience, or both, is associated with lower immediate post-exercise levels of plasma enzyme activity. This is compatible with the finding that physical training reduces post-exercise plasma enzyme levels.

The responses of plasma biochemical parameters to a 56-km race in novice and experienced ultra-marathon runners

In order to study the influence of physical exercise on liver function, experiments were performed in healthy volunteers subjected to controlled major physical effort. Blood samples obtained by catheterization of hepatic vein during exercise were analyzed for activities of LD (thermostabile and thermolabile isoenzymes), AIAT, SDH, ICD, AP and CPK, and these activities were compared with corresponding values in arterial blood samples taken simultaneously. Hepatic blood flow and oxygen saturation of hepatic venous blood were measured. Physical exercise resulted both in diminished hepatic blood flow and a fall in hepatic venous oxygen saturation. These changes were accompanied by release of liver specific enzymes, indicating that exhausting exercise may induce an “increased hepatocyte membrane permeability” in man.

Enzyme activities in hepatic venous blood under strenuous physical exercise

Branched-chain amino acid (BCAA) supplementation is becoming more widely used by athletes in an attempt to improve their recovery between training or competition. This study examined the effects of the supplementation on indicators of muscle damage after intense prolonged exercise. Sixteen male subjects were used in the study with eight taking BCAA supplementation and eight acting as the control group. The experimental group were required to take the manufacturer's recommended dose for the 14 days oi iesiing. For the seven days before the exercise test both groups had their blood analysed every second day for creatine kinase and lactate dehydrogenase which have been shown to be accurate indicators of muscle damage. The exercise test was a 120 minute bicycle ride at 70% of their predetermined VO2max. Directly after the exercise
and hourly for 4 hours all subjects again had blood samples analysed. The experimental group continued to take supplementation for 7 days after the test and all subjects had their blood analysed every second day. Subjects were also required to keep activity to a minimum and have their diet analysed during the 14 days and manipulated if necessary to ensure that the recommended daily Intake of BCAA's were being consumed as part of their normal diet. Results indicated that all subjects' diets did not require manipulation as they all consumed the recommended daily intake of BCAA's in their normal diet. No significant differences were found between any of the two enzyme values in the 7 days prior to the test. There were, however, significant changes in pre-exercise and post-exercise values for LDH at 2 hrs., 3 hrs., 4 hrs., 1 day, 2 days and 4 days after the test (p<0.05). There were also significant changes in pre -exercise and post-exercise values for CK at 4 hrs., 1 day, 2 days and 4 days after the test. The BCAA was shown to significantly (p<0.05) reduce this change in LDH at 3 hrs., 4 hrs. and 1 day and CK at 4 hrs., 1 day and 2 days post exercise. These results indicate that supplementary Branched Chain Amino Acids significantly reduce the levels of the intramuscular enzymes creatine kinase and lactate dehydrogenase after prolonged strenuous exercise. This suggests that the supplementation may reduce muscle damage.

/pdf/the-effects-of-branched-chain-amino-acid-supplementation-on-2vof3oro43.pdf

The Effects of Branched Chain Amino Acid Supplementation on Indicators of Muscle Damage after Prolonged Strenuous Exercise

Effect of exercise on serum enzyme levels in trained subjects.

The purpose of this study was to investigate the effect of increasing the intensity of exercise on serum enzyme levels in untrained males. Subjects exercised on a treadmill at one of four inclines for 15 minutes, and serum enzyme determinations were made before and after exercise. Results showed a greater increase in mean serum enzyme levels after strenuous exercise than after either mild or moderate exercise. Variations in serum enzyme concentrations between subjects, as well as differences in the relative increases of enzymes, were shown to exist.

Effect of Exercise on Serum Enzyme Levels in Untrained Males

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Effect of exercise on serum enzyme levels in trained subjects.

Effect of Exercise on Serum Enzyme Levels in Untrained Males