176
Effects of Chronic Intense Exercise Training on the Leukocyte Response to Acute Exercise .1. A, Ndon, A. C. Snyder, C. Foster, W. B. Wehrenberg Department of Health Sciences and Department of Human Kinetics, University of Wisconsin-Milwaukee, WI, 53211
Introduction J. A. Ndon, A. C. Snyder, C. Foster and W. B. Wehrenberg, Effects of Chronic Intense Exercise Training on the Leukocyte Response to Acute Exercise. mt J Sports Med,Vol 13,No2,pp 176—182,1992.
Accepted: August 18, 1991
Circulatory leukocytes vary significantly in
response to acute bouts of exercise. However, little is known concerning the adaptability of this response to chronic intense exercise training. We investigated the circulating leukocytic response to acute exercise in trained athletes during a 28-day intense exercise training program. On day 0, 14, 28 and two days after cessation of the increased training, eight trained male athletes (VO2max> 60 mlkg min — 5 were subjected to a 20-km bicycle ergometer time
trial. Blood samples were drawn before (PRE, for resting baseline values) and five minutes after (POST, response to acute exercise) the time trial. Beginning on day 0, athletes
were instructed to increase the duration of their training 50%. The intense exercise training, which lasted 28 days, was verified weekly. Acute bouts of exercise caused a signif-
Competition and recreation have been the traditional motives for sports. Without question the motivation now also includes the fact that exercise training provides numerous health benefits (18, 32, 35, 40,41). Regular exercise and physical activity have been established as a means of reducing the risk of cardiovascular disease (40, 41) and contributing to longevity (18). It is generally believed that regular exercise increases resistance to infectious disease (42), but recent reports have associated overtraining in athletes with increased susceptibility to infections (21, 25). Similarly, physicians who have treated athletes in Olympic games (16, 22), as well as those who have treated athletes in private (17), have reported that the risk of an infection, particularly upper respiratory and gastrointestinal, is higher in athletes than for non-athletes. Since there is a direct relationship between the immune system and susceptibility to infectious agents, investigators have focused on the possible effects of exercise on immune function (21, 27, 34, 45). Many investigators have implied that regular and moderate exercise may improve the ability of the immune system to protect the host against infection (21, 23, 37). In contrast, some investigators have associated acute and exhaustive exercise with decreased immune function and increased susceptibility to infections (42). A study by Lewicki and associ-
icant increase (p < 0.05) in circulating white blood cells, lymphocytes, polymorphonuclear neutrophils and monocytes. The baseline resting values and the magnitude of the response to the acute bouts of exercise in the above parameters were not different during the 28 days of chronic intense exercise training or 2 days after cessation of training as compared to the values observed on day 0. Similarly there was a significant increase (p < 0.05) in cortisol levels
ates (26) provides evidence that repeated exercise may
in response to the acute bouts of exercise during the chronic intense exercise training, but the increases were not different from that observed under baseline conditions. These re-
tribution of circulating lymphocyte sub-populations (10, 13, 38, 42), and decreased salivary IgA (28, 29). Many of the observed changes appear to be transient and most of these responses appear to return to normal within hours after the exercise stimulus.
sults lead to the conclusion that chronic intense exercise training does not alter the circulating leukocytic response to acute exercise. Key words
Acute exercise, chronic exercise, leukocytes
Int.J.SportsMed. 13(1992)176— 182 GeorgThieme Verlag Stuttgart New York
suppress nonspecific immunity, which would render athletes more susceptible to infection. Both human (20, 26, 31, 34, 36) and animal (39) studies suggest that the timing and intensity of exercise are important in determining how exercise influences the immune system. Among the consistently observed changes in immune parameters after exercise are leukocytosis (6, 9, 14, 15, 20, 30, 31), increase in natural killer cells (10, 13, 27), redis-
The present study was designed to monitor changes in the number of leukocytes and their sub-populations, during rest and following acute exercise, in trained athletes who followed a chronic intense exercise training program for four weeks. Changes in serum IgA and cortisol were also monitored.
Downloaded by: University of British Columbia. Copyrighted material.
Abstract
mt. J. Sports Med. 13(1992) 177
Chronic In tense Exercise Training and Leukocyte Response
Subjects Ten well-trained male cyclists/triathietes who met minimum training and performance criteria were selected for this study. The inclusion criteria included a maximal oxy-
gen uptake (VO2max) of greater than 60 mlkg min tand the ability to complete a 20-km bicycle ergometer time trial in less than 32.5 minutes. Each subject voluntarily signed an informed consent statement approved by the University of Wisconsin-Milwaukee Institutional Review Board for Protection of Human Subjects. Body weight and height were obtained during a period of normal training and during the fourth week
of heavier than normal training. Maximal oxygen uptake (VO2max) was determined during an incremental exercise cycling test with open circuit spirometry (43). Percent body fat
was determined from a seven-site skinfold test (7). Results from only eight of the subjects are presented as two subjects were excluded since they showed signs of overtraining i. e., performance decrements.
three sub-populations, lymphocytes, mononuclear cells and granulocyte cells, the data were corroborated by identifying and enumerating 200 white blood cells on Wright's stained blood smear of each sample. Absolute polymorphonuclear neutrophil (PMN), monocyte and lymphocyte counts were calculated from the total WBC and percent of cell count from the differential count. In addition, serum immunoglobulin A (IgA) was measured using radial immunodiffusion plates (Behring Diagnostic mc, Somerville, NJ). Serum cortisol levels were measured using a radioimmunoassay kit (Diagnostic Products, Los Angeles, CA). The hematocrit and hemoglobin were determined for each sample. This information was incorporated into the formulas of Dill and Costill (11) to calculate the percent change in plasma volume in response to acute and chronic exercise.
Statistical Analysis Data were subjected to analysis of variance with consideration given to repeated measures (47) using the
MANOVA module of the Statistical Package for Social Acute and Chronic Exercise
Sciences, Inc. (SPSS, Chicago, IL). Statistical significance was
On day 0 of the experiment all subjects re-
mean SEM.
set at the p < 0.05 level. All data are expressed as
ported to the laboratory after a 12 h fast. Each athlete was subjected to an acute bout of exercise which consisted of a 20-km
Results
bicycle ergometer time trial on a wind-loaded simulator. Throughout the time trial, the subjects were aware of the speed and distance traveled but were not told elapsed time. All time-
related visual cues were eliminated. They were verbally encouraged throughout the ride. Blood samples were obtained by venipuncture in EDTA-coated and plain tubes while subjects were seated 5 mm prior to the acute bout of exercise (PRE) and five minutes following the acute exercise (POST). The blood samples from day 0 were used to establish the base-
The physical characteristics of the eight male subjects prior to the onset of chronic intense exercise training are presented in Table 1. The subjects significantly increased
their training duration (Pre = 434 173; Post 752 199 mm per week, p < 0.05). The time trial values for the 20-km bicycle ergometer test were 30.9 0.4 mm prior to the onset of chronic intense exercise training. Performance improved though not significantly as reflected on time trial values
line values and the response values to an acute bout of exercise during normal training for several hematological parameters. Following establishment of these baseline values, the subjects
decreasing to 29.5 0.3 mm by the end of the intense training period. These time trial values clearly indicated that these subjects were fit, training and met the performance criteria for in-
were instructed to increase the duration of their training by 50%. Since monotony in training could result in overtraining, the athletes were allowed to perform any activity (e. g., cy-
clusion in the study. Furthermore, they further demonstrated that the subjects were not overtrained. Estimated exercise
cling, running, swimming, weight lifting); however, they were encouraged to perform most of their training cycling. During the four weeks of heavy training the subjects were not allowed any days off(i. e., no rest days). The athletes were told to keep record of their daily activities during the four weeks of heavy training. This included the types of exercise performed and the duration of the exercise. None of the eight subjects included in the study reported being sick during the period of intense training. They reported that they spent 75 to 80% of the time cycling and 20 to 25% of the time running, swimming and weight lifting during the period of intense training. On day 14 and 28 of the heavy training and again following two days of recovery (i. e., day 30), the subjects were again challenged to a 20-km cy-
cling time trial in the laboratory. Blood was again obtained before and after the acute exercise.
energy expenditure increased from 994 157 kcal/training session prior to onset of chronic intense exercise training to 1777 180 kcal/training session during the heavy training period. Body weight after (73.8
paired t-test). Hematocrits averaged 44.3 0.4% prior to acute exercise and 46.8 0.4% following acute exercise. Plasma volume decreased 10.0 0.9% in response to acute exercise. There were no differences in the decrease in plasma volume on the different days.
Physiological ch aracteristics of th e eight male subjects prior to the onset of chron ic intense exercis e training Table 1
Characteristic
Hematological and Immune Parameters Complete blood cell counts and differential counts of white blood cells (WBC) were performed on a Coulter Counter S-Plus IV (Coulter Electronics, Inc., Hialeah, FL). Since this analyzer differentiates white blood cells into only
1.0 kg) the chronic intense
exercise training period was significantly lower than body weight prior to the intense training (74.8 1.9 kg, p
Effects of Chronic Intense Exercise Training on the Leukocyte Response to Acute Exercise .1. A, Ndon, A. C. Snyder, C. Foster, W. B. Wehrenberg Department of Health Sciences and Department of Human Kinetics, University of Wisconsin-Milwaukee, WI, 53211
Introduction J. A. Ndon, A. C. Snyder, C. Foster and W. B. Wehrenberg, Effects of Chronic Intense Exercise Training on the Leukocyte Response to Acute Exercise. mt J Sports Med,Vol 13,No2,pp 176—182,1992.
Accepted: August 18, 1991
Circulatory leukocytes vary significantly in
response to acute bouts of exercise. However, little is known concerning the adaptability of this response to chronic intense exercise training. We investigated the circulating leukocytic response to acute exercise in trained athletes during a 28-day intense exercise training program. On day 0, 14, 28 and two days after cessation of the increased training, eight trained male athletes (VO2max> 60 mlkg min — 5 were subjected to a 20-km bicycle ergometer time
trial. Blood samples were drawn before (PRE, for resting baseline values) and five minutes after (POST, response to acute exercise) the time trial. Beginning on day 0, athletes
were instructed to increase the duration of their training 50%. The intense exercise training, which lasted 28 days, was verified weekly. Acute bouts of exercise caused a signif-
Competition and recreation have been the traditional motives for sports. Without question the motivation now also includes the fact that exercise training provides numerous health benefits (18, 32, 35, 40,41). Regular exercise and physical activity have been established as a means of reducing the risk of cardiovascular disease (40, 41) and contributing to longevity (18). It is generally believed that regular exercise increases resistance to infectious disease (42), but recent reports have associated overtraining in athletes with increased susceptibility to infections (21, 25). Similarly, physicians who have treated athletes in Olympic games (16, 22), as well as those who have treated athletes in private (17), have reported that the risk of an infection, particularly upper respiratory and gastrointestinal, is higher in athletes than for non-athletes. Since there is a direct relationship between the immune system and susceptibility to infectious agents, investigators have focused on the possible effects of exercise on immune function (21, 27, 34, 45). Many investigators have implied that regular and moderate exercise may improve the ability of the immune system to protect the host against infection (21, 23, 37). In contrast, some investigators have associated acute and exhaustive exercise with decreased immune function and increased susceptibility to infections (42). A study by Lewicki and associ-
icant increase (p < 0.05) in circulating white blood cells, lymphocytes, polymorphonuclear neutrophils and monocytes. The baseline resting values and the magnitude of the response to the acute bouts of exercise in the above parameters were not different during the 28 days of chronic intense exercise training or 2 days after cessation of training as compared to the values observed on day 0. Similarly there was a significant increase (p < 0.05) in cortisol levels
ates (26) provides evidence that repeated exercise may
in response to the acute bouts of exercise during the chronic intense exercise training, but the increases were not different from that observed under baseline conditions. These re-
tribution of circulating lymphocyte sub-populations (10, 13, 38, 42), and decreased salivary IgA (28, 29). Many of the observed changes appear to be transient and most of these responses appear to return to normal within hours after the exercise stimulus.
sults lead to the conclusion that chronic intense exercise training does not alter the circulating leukocytic response to acute exercise. Key words
Acute exercise, chronic exercise, leukocytes
Int.J.SportsMed. 13(1992)176— 182 GeorgThieme Verlag Stuttgart New York
suppress nonspecific immunity, which would render athletes more susceptible to infection. Both human (20, 26, 31, 34, 36) and animal (39) studies suggest that the timing and intensity of exercise are important in determining how exercise influences the immune system. Among the consistently observed changes in immune parameters after exercise are leukocytosis (6, 9, 14, 15, 20, 30, 31), increase in natural killer cells (10, 13, 27), redis-
The present study was designed to monitor changes in the number of leukocytes and their sub-populations, during rest and following acute exercise, in trained athletes who followed a chronic intense exercise training program for four weeks. Changes in serum IgA and cortisol were also monitored.
Downloaded by: University of British Columbia. Copyrighted material.
Abstract
mt. J. Sports Med. 13(1992) 177
Chronic In tense Exercise Training and Leukocyte Response
Subjects Ten well-trained male cyclists/triathietes who met minimum training and performance criteria were selected for this study. The inclusion criteria included a maximal oxy-
gen uptake (VO2max) of greater than 60 mlkg min tand the ability to complete a 20-km bicycle ergometer time trial in less than 32.5 minutes. Each subject voluntarily signed an informed consent statement approved by the University of Wisconsin-Milwaukee Institutional Review Board for Protection of Human Subjects. Body weight and height were obtained during a period of normal training and during the fourth week
of heavier than normal training. Maximal oxygen uptake (VO2max) was determined during an incremental exercise cycling test with open circuit spirometry (43). Percent body fat
was determined from a seven-site skinfold test (7). Results from only eight of the subjects are presented as two subjects were excluded since they showed signs of overtraining i. e., performance decrements.
three sub-populations, lymphocytes, mononuclear cells and granulocyte cells, the data were corroborated by identifying and enumerating 200 white blood cells on Wright's stained blood smear of each sample. Absolute polymorphonuclear neutrophil (PMN), monocyte and lymphocyte counts were calculated from the total WBC and percent of cell count from the differential count. In addition, serum immunoglobulin A (IgA) was measured using radial immunodiffusion plates (Behring Diagnostic mc, Somerville, NJ). Serum cortisol levels were measured using a radioimmunoassay kit (Diagnostic Products, Los Angeles, CA). The hematocrit and hemoglobin were determined for each sample. This information was incorporated into the formulas of Dill and Costill (11) to calculate the percent change in plasma volume in response to acute and chronic exercise.
Statistical Analysis Data were subjected to analysis of variance with consideration given to repeated measures (47) using the
MANOVA module of the Statistical Package for Social Acute and Chronic Exercise
Sciences, Inc. (SPSS, Chicago, IL). Statistical significance was
On day 0 of the experiment all subjects re-
mean SEM.
set at the p < 0.05 level. All data are expressed as
ported to the laboratory after a 12 h fast. Each athlete was subjected to an acute bout of exercise which consisted of a 20-km
Results
bicycle ergometer time trial on a wind-loaded simulator. Throughout the time trial, the subjects were aware of the speed and distance traveled but were not told elapsed time. All time-
related visual cues were eliminated. They were verbally encouraged throughout the ride. Blood samples were obtained by venipuncture in EDTA-coated and plain tubes while subjects were seated 5 mm prior to the acute bout of exercise (PRE) and five minutes following the acute exercise (POST). The blood samples from day 0 were used to establish the base-
The physical characteristics of the eight male subjects prior to the onset of chronic intense exercise training are presented in Table 1. The subjects significantly increased
their training duration (Pre = 434 173; Post 752 199 mm per week, p < 0.05). The time trial values for the 20-km bicycle ergometer test were 30.9 0.4 mm prior to the onset of chronic intense exercise training. Performance improved though not significantly as reflected on time trial values
line values and the response values to an acute bout of exercise during normal training for several hematological parameters. Following establishment of these baseline values, the subjects
decreasing to 29.5 0.3 mm by the end of the intense training period. These time trial values clearly indicated that these subjects were fit, training and met the performance criteria for in-
were instructed to increase the duration of their training by 50%. Since monotony in training could result in overtraining, the athletes were allowed to perform any activity (e. g., cy-
clusion in the study. Furthermore, they further demonstrated that the subjects were not overtrained. Estimated exercise
cling, running, swimming, weight lifting); however, they were encouraged to perform most of their training cycling. During the four weeks of heavy training the subjects were not allowed any days off(i. e., no rest days). The athletes were told to keep record of their daily activities during the four weeks of heavy training. This included the types of exercise performed and the duration of the exercise. None of the eight subjects included in the study reported being sick during the period of intense training. They reported that they spent 75 to 80% of the time cycling and 20 to 25% of the time running, swimming and weight lifting during the period of intense training. On day 14 and 28 of the heavy training and again following two days of recovery (i. e., day 30), the subjects were again challenged to a 20-km cy-
cling time trial in the laboratory. Blood was again obtained before and after the acute exercise.
energy expenditure increased from 994 157 kcal/training session prior to onset of chronic intense exercise training to 1777 180 kcal/training session during the heavy training period. Body weight after (73.8
paired t-test). Hematocrits averaged 44.3 0.4% prior to acute exercise and 46.8 0.4% following acute exercise. Plasma volume decreased 10.0 0.9% in response to acute exercise. There were no differences in the decrease in plasma volume on the different days.
Physiological ch aracteristics of th e eight male subjects prior to the onset of chron ic intense exercis e training Table 1
Characteristic
Hematological and Immune Parameters Complete blood cell counts and differential counts of white blood cells (WBC) were performed on a Coulter Counter S-Plus IV (Coulter Electronics, Inc., Hialeah, FL). Since this analyzer differentiates white blood cells into only
1.0 kg) the chronic intense
exercise training period was significantly lower than body weight prior to the intense training (74.8 1.9 kg, p
