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We investigated whether there is a break point of creatine kinase (CK) release after daily endurance exercise and whether CK response depends on individual physical characteristics. Fifteen healthy young men performed 90 min of bicycle exercise for 3 consecutive days. Body composition, properties of the quadriceps femoris muscle (QFM), and aerobic and anaerobic capacities were estimated before the test. Blood samples were obtained 22 times during the experimental period. Endurance exercise significantly elevated serum CK from 3 h after the first exercise session (P < 0.05) and gradually increased thereafter. Subjects were classified into two groups according to their peak CK values: high responders (HR; >500 IU/l of CK) and low responders (LR; <300 IU/l of CK). Peak CK values during the experimental period correlated (P< 0.01) with workload/cross-sectional area of the QFM (r= 0.658), workload/volume of the QFM (r= 0.648), and knee extensor strength/body mass (r= −0.634); however, the HR and LR groups were separated in each variable. Thus the break point of CK release after endurance exercise under these conditions is 300–500 IU/l, two or three times higher than in the resting condition, and is associated with properties of the QFM.

We examined the hypothesis that the short, intensive exercise-induced increase in circulating neutrophil counts is affected by the interaction between the endocrine and immune systems. Twelve male winter-sports athletes underwent a maximal exercise test on a treadmill. Blood samples were collected before, immediately after (Post), and 1 h (Post 1 h) and 2 h (Post 2 h) after the exercise. The neutrophil counts increased significantly at Post 1 h (P< 0.05) and remained significantly high even at Post 2 h (P< 0.05), showing a leftward shift. Plasma granulocyte colony-stimulating factor (G-CSF) increased at Post (P< 0.05), and interleukin-6 (IL-6) increased at Post 1 h (P< 0.05). Plasma G-CSF at Post significantly correlated with the numbers of both neutrophils and stab cells at Post 1 h (P< 0.05). Plasma IL-6 at Post 1 h levels also correlated significantly with the number of neutrophils at Post 2 h (P< 0.05). The increase in the levels of plasma G-CSF and IL-6 after intensive exercise may play a role in the mobilization of neutrophils into the circulatory system.

We studied changes in serum opsonic activity (SOA) in male judoists who were engaged in active weight reduction. Serum immunoglobulins, complements and SOA, measured by neutrophil‐associated chemiluminescence responses, were investigated 20 days, 7 days and 1 day before a competition and 5 days after the competition. In addition, muscle strength and anaerobic work capacity, as well as body composition, were also determined. A dietary survey was conducted daily during the observation period. Body weight decreased by 4.2 kg over 19 days. SOA significantly decreased 5 days after the competition, as well as the concentrations of serum immunoglobulins, complements and total proteins. These trends were noted in the marked weight reduction group (i.e. reduction weight of body fat/body fat weight before weight reduction ≧25%) more than the slight reduction group (<25%). Depressed SOA was closely correlated with the decreased concentrations of immunoglobulins and complements. These results suggest that the decrease in immunoglobulins and complements following weight reduction is associated with reduced SOA, which might cause susceptibility to infections. This study demonstrated that such immunosuppression appeared in the recovery period after the competition rather than immediately before the competition. Copyright © 2002 John Wiley & Sons, Ltd.

In order to investigate the effect of exercise on the capacity of neutrophils to produce reactive oxygen species (ROS), eight male cross-country skiers underwent maximal exercise. Peripheral blood samples were taken pre-exercise, 0 h, 1 h, and 2 h after finishing maximal exercise. Leukocyte counts significantly increased (p &lt; 0.05), particularly lymphocytes (p &lt; 0.05), just after the exercise period (0 h) and significantly increased again (p &lt; 0.05), particularly neutrophils (p &lt; 0.05), 2 h after the exercise compared with pre-exercise values. The capacity of isolated neutrophils to produce ROS was assessed by lucigenin (Lg)-dependent chemiluminescence (CL) and luminol (Lm)-dependent CL on stimulation with opsonized zymosan (OZ) and phorbol myristate acetate (PMA). Just after exercise, the LgCL response was not affected, while the response of LmCL mixed with sodium azide, which inhibits catalase and myeloperoxidase (MPO) activity, was significantly enhanced (p &lt; 0.05). In addition, just after exercise, the level of serum growth hormone increased significantly (p &lt; 0.05). The serum cortisol level also increased significantly just after and 1 h after exercise (p &lt; 0.05). These data indicated that maximal exercise not only mobilized neutrophils from marginated pools into the circulation, but also caused increased ROS generation. Copyright © 2000 John Wiley & Sons, Ltd.

In order to investigate the effect of exercise on the capacity of neutrophils to produce reactive oxygen species (ROS), eight male cross‐country skiers underwent maximal exercise. Peripheral blood samples were taken pre‐exercise, 0 h, 1 h, and 2 h after finishing maximal exercise. Leukocyte counts significantly increased (p< 0.05), particularly lymphocytes (p< 0.05), just after the exercise period (0 h) and significantly increased again (p< 0.05), particularly neutrophils (p< 0.05), 2 h after the exercise compared with pre‐exercise values. The capacity of isolated neutrophils to produce ROS was assessed by lucigenin (Lg)‐dependent chemiluminescence (CL) and luminol (Lm)‐dependent CL on stimulation with opsonized zymosan (OZ) and phorbol myristate acetate (PMA). Just after exercise, the LgCL response was not affected, while the response of LmCL mixed with sodium azide, which inhibits catalase and myeloperoxidase (MPO) activity, was significantly enhanced (p< 0.05). In addition, just after exercise, the level of serum growth hormone increased significantly (p< 0.05). The serum cortisol level also increased significantly just after and 1 h after exercise (p< 0.05). These data indicated that maximal exercise not only mobilized neutrophils from marginated pools into the circulation, but also caused increased ROS generation. Copyright © 2000 John Wiley & Sons, Ltd.

We analyzed adaptation mechanisms regulating systemic inflammatory response of the stressed body by using an experimental challenge of repeated exercise bouts and accompanying muscle inflammation. Eight untrained men bicycled at 90 W for 90 min, 3 days in a row. Exercise induced peripheral neutrophilia with a leftward shift of neutrophil nucleus and neutrophil priming for oxidative activity determined by luminol-dependent chemiluminescence. Plasma growth hormone and interleukin-6 rose significantly after exercise and were closely correlated with the neutrophil responses. Serum creatine kinase and myoglobin levels as muscle damage markers rose after exercise in “delayed onset” and were closely correlated with the preceding neutrophil responses. These exercise-induced responses were strongest on day 1, but the magnitude gradually decreased with progressive daily exercise. In contrast, the magnitude of catecholamine responses to exercise sessions gradually rose, possibly suppressing neutrophil oxidative responses. These results indicate that stress-induced systemic release of bioactive substances may determine neutrophil mobilization and functional status, which then may affect local tissue damage of susceptible organs.

Gender-related differences in anthropometry, blood biochemistry, psychological parameters, and energy intake during prematch weight reduction were studied in 22 men and 7 women college judoists who lost weight by combining judo training, restricting food and fluid, and sweating. Body weight (BW) decreased significantly by 2.2±1.4 kg in men and 2.0±1.4 kg in women 2 weeks after weight reduction started — not significandy different. Body fat, relative body fat and total energy intake also decreased significandy in both groups 2 weeks after weight reduction started. Lean body mass decreased significandy 2 weeks after weight reduction started only in men. Men had significantly decreased blood lipids, immunoglobulins, complements, hematocrit, white blood cell count, and serum electrolytes, and significant increases in blood uric nitrogen, creatinine, and hemoglobin, while women showed no such changes. The score for vigor in the Profile of Mood States (POMS) decreased in both groups 2 weeks after weight reduction started, but with no statistically gender difference. In women, scores for anxiety in the State-Trait Anxiety Inventory (STAI) and confusion in POMS increased significandy. Although the men and women had the same BW reduction, significant physical stress response was seen only in men, and psychological stress due to weight reduction and mental pressure of an upcoming competition were seen more in women.

Summary: We examined the influence exerted, through disuse of the hindlimb, on the collagen fibres of the achilles tendon in rats. With disuse the body mass decreased by 28%, and the mass of soleus muscle decreased by 20%. A decrease in the surface area and diameter was observed in the experimental group when compared to the control group. A histogram of the collagen fibres showed a decrease of the thick fibres in the experimental group. The maximum surface area of collagen fibres in the experimental group was seen to be only 43% of that of the control group. These results showed a decrease in the thickness of the collagen fibres of the achilles tendon through disuse. This seemed to suggest that resistance to tension is decreased by disuse.