ABSTRACT
We investigated both the acute effects of maximal exercise and the chronic effects of training on nonspecific immunity in 15 winter-sports athletes during different periods of training : (a) before the athletic season, in summer, when the athletes were undertaking extensive endurance training to enhance aerobic capacity, (b) during the winter sports season, in early winter, when endurance and athletic training were being undertaken, and (c) after the winter sports season, in spring, when the athletes were resting (detraining for a month) . The mean value of the maximal oxygen uptake in each training period was (a) 65.4 (SD 4.6) mL·kg<SUP>-1</SUP>·min<SUP>-1</SUP>, (b) 63.1 (SD 5.5) mL· kg<SUP>-1</SUP>·min<SUP>-1</SUP>, and (c) 58.3 (SD 5.8) mL·kg<SUP>-1</SUP>·min<SUP>-1</SUP>, respectively. Following maximal exercise, acute peripheral leukocytosis due to lymphocytosis and neutrophila was observed in every period. The capacity of isolated neutrophils to produce reactive oxygen species upon stimulation with opsonized zymosan measure by luminol-dependent chemiluminescence (LDCL) was significantly enhanced after maximal exercise before and during the athletic season. However, the degree of enhancement was smaller during after-season detraining, suggesting that the conditioning state affected the exercise-induced changes in neutophil functional status. Serum opsonic activity also showed a similar pattern. As for the chronic effects of training, the resting values of the neutrophil count, especially the segmented neutrophil count, the neutrophil LDCL response and the serum IgG level, declined significantly in the pre-season training period. Since the subjects were engaged in exhaustive endurance training under heat exposure at that time, the nonspecific immune status might have been partially compromised due to chronic overload.
ABSTRACT
Twenty endurance-trained athletes (five male speed-skaters, eleven male and four female cross-country skiers, 16-18 years) ran on a treadmill by a protocol of incremental graded increase in workload until exhaustion during an endurance training period in off-season summer. Immediately after exercise, all developed peripheral leukocytosis (1.9 times; p<0.01) due mainly to lymphocytosis (2.6 times; p<0.01) with a predominant effect on large granular lymphocyte (natural killer cell) count (5.9 times ; p<0.01) . Monocyte count was also enhanced 2.3 times (p<0.01) . These increases were transitory and returned to the pre-exercise levels 1 h later. Peripheral neutrophilia was also observed by 43% (p<0.01) immediately after exercise and remained elevated by 25% (p<0.01) 1 h after exercise, but a shift to the left did not take place. The capacity of isolated neutrophils to produce reactive oxygen species was assessed by luminol-dependent chemiluminescence which detects mainly myeloperoxidase (MPO) -mediated formation of such hyperreactive oxidants as HOCl. The maximum intensity of chemiluminescence (peak height) upon stimulation with opsonized zymosan was significantly enhanced following exercise (p<0.05) . Similar results were obtained when phorbol myristate acetate was employed as nonphagocytic soluble stimulus (p<0.01), suggesting that the capacity of neutrophils to degranulate MPO rather than phagocytosis was enhanced following exercise. In addition, the enhancements of chemiluminescence were positively correlated with the increase in segmented neutrophil count. These data indicate that maximal exercise not only mobilized mature neutrophils from the marginated pool into the circulation, but also augmented their capacity to generate reactive oxygen species of higher reactivity.
ABSTRACT
A study was conducted to investigate the relationship between energy systems and running performance, especially during the last spurt in an 800-m race. The subjects were separated into good 800-m runners (group A n=5: best record, 1′54″3±1.4) and a second group of slower 800-m runners (group B n=4: best record, 2′02″1±1.3) . Each group executed two types of running test (600m test and 800m test) . To simulate an 800-m race, the running speed up to 600m was set by means of a lamp pace maker system. The last spurt was running 200m at maximal voluntary running speed. Plasma lactate, plasma ammonia, serum glucose and blood pH were assayed at rest, after warming up, and 6 and 10min after the running test.<BR>The following results were obtained:<BR>1) The last spurt time of group A was significantly faster than that of group B (p<0.01) . 2) In group A, plasma lactate and plasma ammonia concentrations increased significantly during the last spurt (p<0.05) . In group B, however, plasma lactate and plasma ammonia concentrations before the last spurt (600m test values) were very close to the values after the last spurt (800m test values), 3) Last spurt times were significantly related to changes in plasma lactate concentration (r=-0.870, p<0.01) and O<SUP>2</SUP> debt (r=-0.799, p<0.01) during the last spurt.<BR>These results suggest that running performance during the last spurt in an 800-m race depends on anaerobic energy ability, as reflected by plasma lactate, plasma ammonia and O<SUP>2</SUP> debt before the last spurt.
ABSTRACT
With disuse, e. g. that resulting from tail-suspension, skeletal muscle shows a decrease in both mass and strength, with concomitant atrophy. Type IIc fibers are observed during muscle fiber generation, regeneration and fiber type transformation. Thus, the recovery process of atrophied muscle fibers can be investigated by observing changes in type IIc fiber distribution. In this study, the behavior of type IIc fibers was examined in rats during recovery following 5 weeks of tail-suspension. Male rats were assigned to three groups : control (C), tailsuspension (S), and pair-weight (P), in which body weight was adjusted to that of the S group by controlled food consumption.<BR>The results were as follows : 1) After 5 weeks of tail-suspension, the weight of the m. soleus in the S group was less than 40% of that in the C group. 2) Weights of all muscles removed in the S group increased rapidly until 2 weeks into the recovery period, and returned to the level in the P group by 5 weeks. 3) Type IIc fiber distribution in the m, soleus in the S group was increased by about 35% after 5 weeks of tail-suspension, and had not returned to the level in the C group by 5 weeks of recovery. 4) Phanocytosis and central nuclei were observed in the atrophic muscle fibers of the S group.