467
The Effects of Moderate Exercise Training on Natural Kifier Cells and Acute Upper Respiratory Tract Infections D. C. Nieman, S. L. Nehlsen-Cannarel!a, P. A. Markoff A. J. Balk-Lamberton, H. Yang, D. B. W. Chritton, J. W. Lee, and K. Arabatzis Department of Health Science, School of Public Health Loma Linda University. Immunology Center, Loma Linda University Medical Center.
D. C. Nieman, S. L. Nehisen-Cannarella, P. A. Markoff A. J. Balk-Lamberton, H. Yang, D. B. W. Chrition, J. W. Lee, K. Arabatzis, The Effects of Moderate Exercise Training on Natural Killer Cells and Acute Upper Respira-
tory Tract Infections. Tnt J Sports Mcd, Vol 11, No 6, pp 467—473,1990.
Accepted after revision: February 12, 1990
A randomly controlled 1 5-wk exercise training (El) study (five 45-mm sessions/wk, brisk walking at 60% heart rate reserve) with a group of 36 mildly obese, sedentary women was conducted to investigate the relationship between improvement in cardiorespiratory fitness, changes in natural killer (NK) cell number and activity, and acute upper respiratory tract infection (URI) symptomatology. The study was conducted using a 2 (exercise and nonexercise groups) x 3 (baseline, 6-, and 1 5-wk testing sessions) factorial design, with data analyzed using repeated measures ANOVA. No significant change in NK cell number occurred as a result of ET as measured by the CD16 and Leu-19 nionoclonal antibodies. El did have a significant effect on NK cell activity (E:T 50:1) especially during the initial 6-wk period [F(2,68) = 12.34, p< 0.0011. Using data from daily logs kept by each subject, the exercise group was found to have significantly fewer URI symptom
days/incident than the nonexercise group (3.6±0.7 vs 7.0 1.4 days, respectively, p = 0.049). Improvement in cardiorespiratory fitness was correlated significantly with a
reduction in URI symptom days/incident (r = 0.37, p = 0.025) and a change in NK cell activity from baseline to six but not 15 wks (r 0.35, p= 0.036). In summary, moderate ET is associated with elevated NK cell activity after six
but not 15 weeks, and reduced URI symptomatology in comparison to a randomized, sedentary control group. Key words
exercise, upper respiratory tract infections, natural killer cell activity, immune system
Acute upper respiratory tract infections (URI) impose a significant burden each year in terms of days of disability, lost school or work days, and medical costs (23). The Centers for Disease Control has estimated that 429 million URI occur annually in the US resulting in $2.5 billion in direct costs (37). The 1987 US incidence rates per 100 persons per year for all acute respiratory conditions was 80.1, led by influenza (38.2) and the common cold (25.9) (23). There is a growing interest in the effects of both
acute and chronic exercise on immunosurveillance and host protection (14, 18—22, 26, 30, 33, 35, 40). Although it is generally believed that exercise training increases resistance to URI, little scientific evidence exists to support this contention. Most
studies have examined the effects of acute submaximal and maximal exercise on changes in immune system parameters and function, providing little direct evidence as to how these alterations affect resistance to URI. Few prospective studies have been conducted in this area, and none have utilized randomized sedentary control groups (35, 40).
A better understanding of the relationship between exercise and URI may be gained by investigating the effects of exercise training on natural killer (NK) cells and their
activity. NK cells, first discovered in the early 1970s, are unique in that they express spontaneous cytolytic activity against a variety of tumor and virus-infected cells (12, 41). Unlike T lymphocytes, NK cells do not require the involvement of major histocompatibility antigens to initiate cytotoxicity. NK cells account for 10— 15% of mononuclear cells in the peripheral blood, and have been observed to respond rapidly to foreign materials and initially control them until the antigen spe-
cific immune system begins to respond. Thus interest in NK cells and their activity has grown because they represent a major first line defense system against viral infection (17, 41).
Nearly all studies to date have measured the acute effect of exercise, both maximal (2, 6, 9, 16) and submaximal (1, 7, 29, 36), on NK cell activity and numbers. We are aware of only two prospective studies that have measured the effects of exercise training on resting NK cell activity in human subjects (5, 40). The studies arrived at different conclusions, with Crist et al. (5) reporting a significant increase in NK
mt. J. Sports Med. 11(1990)467—473 GeorgThieme Verlag StuttgartNew York
cell activity following three months of exercise training and Watson et al. (40) reporting a decrease. In randomized controlled studies utilizing mice, daily exercise training has been
Downloaded by: NYU. Copyrighted material.
Introduction
Abstract
D. C. Niemann eta!.
468 mt. J. Sports Med. 11(1990) associated with a considerable increase in NK cell activity (8) and improved resistance to infection (4). Pedersen et a!. (28)
reported increased levels of NK cell activity at rest in trained vs untrained males, and proposed that the constantly elevated NK cell activity may promote better resistance have
Sin (34) used to determine the percent body fat. Residual volume was measured with the Jaeger constant volume, variable pressure plethysmograph (Erich Jaeger, GmbH & Co.,
Wurzburg, FRD). Body mass index (BMI) was calculated using the formula kg/rn
against TJRI.
randomly controlled 15-week brisk walking study with a group of mildly obese, sedentary, premenopausal women. This type of subject was selected because women of this age have been reported to have the highest rates of URI among adults (23), and to experience considerable cardiorespiratory benefits from regimens of brisk walking (13).
Methods
Subjects
The methods for this study have been described elsewhere (24). A brief description of our methods will be summarized here. Fifty women were selected for this study
who met the following criteria: 25—45 years of age, mildly obese (10—40% overweight), premenopausal, 155—170cm in height, not presently on an exercise program or a reducing diet, a nonsmoker without a history of alcohol or drug abuse, no current use of medications (except oral contraceptives), absence of hypertension and diabetes, and no family history of heart disease. Those who qualified for the study were instructed that they would be randomly assigned to an exercise (EX) or nonexercise (NEX) group. All subjects agreed to accept their randomized placement preceding the study, and were blinded as to the aims of the study. Each subject voluntarily signed an informed consent statement approved by the
Loma Linda University Institutional Review Board for Human Studies.
Maximal graded exercise testing was conducted using the Bruce treadmill protocol on the Quinton Q4000 stress test system and Q55 treadmill (Quinton Instrument Co., Seattle, WA). Metabolic measurements were taken with the Sensor Medics MMC Horizon System 4400 metabolic cart (Sensor Medics, Anaheim, CA).
Exercise Program For 15 weeks the EX group followed a closely supervised walking program on a measured course. This consisted of five 45-mm sessions each week at an intensity of 60% of heart rate reserve. To ensure that the subjects exercised at a proper intensity, heart rates were monitored by checking pulse rates every 0.8 km. At the completion of 45 mm the supervisor recorded their walking distance to the nearest 0.16km. During the 15-week study, the NEX group was instructed not to participate in any exercise outside of normal daily activity.
Subject Recording of URI Symptoms Log books for daily recording of health problems and exercise patterns were given to each subject at baseline. Careful verbal and written instructions were given. Subjects recorded health problems each day of the 15-week study, using 10 codes utilized in a previous study by the Centers for Disease Control (11). The coded health problems included:
cold (runny nose, cough, sore throat), allergy (itchy eyes, stuffy nose), headache, fever, nausea/vomiting/diarrhea, fatigue/tiredness, muscle/joint/bone problem or injury, menstrual cramps, other (describe in blank), or none. URI was
defined when subjects coded for a cold with or without supporting symptoms of headache, fever, fatigue/tiredness,
or nausea/vomiting/diarrhea. An episode of URI was Experimental Design The 15-week research project extended from the last weekend of January to mid-May 1989. Testing was conducted at 3 time periods: baseline, 6 weeks, and 15 weeks. Since exercise training was conducted on weekdays, testing was peformed on Sundays to allow EX subjects a minimum of 36 h of recovery from the last exercise session.
deemed to have commenced if symptoms were coded for a minimum of 48 h and separated by at least one week from a previous episode. Mode of exercise was recorded using 25 coded activities with duration and/or distance reported with each.
Blood Analysis Heparinized whole blood was used for NK cell
All subjects reported to the Loma Linda University Human performance Lab for testing at 0700 h following 12 h of fasting. After resting for at least 5 mm, blood samples were collected. Subjects returned throughout the day for assessment of the following: height and weight, body com-
number and activity assays and EDTA whole blood for
position (hydrostatic weighing and 7-site skinfold tests),
Peripheral blood lymphocytes were isolated by Ficoll-Hypaque centrifugation. Using direct immuno-
resting 12-lead EKG, and 12-lead EKG graded exercise testing with metabolic measurements. If a subject exhibited overt symptoms of URI, the appointment was rescheduled.
Body Composition and Treadmill Testing Body density was determined by hydrostatic weighing, as outlined by Pollock et al. (31), with the formula of
complete blood counts (CBC). CBC were performed on Coulter S-Plus IV instrumentation with visual cell differentials in our clinical hematology laboratory.
fluorescence staining of cell surfaces in lysed whole blood with
mouse anti-human monoclonal antibodies (mAb) from Becton Dickinson Immunocytometry Systems (Mountain View, CA), we analyzed the blood samples for NK cells (CD 16 and Leu-19 [CD undesignated]). Blood samples were also analyzed for other lymphocyte subpopulations, data which are being presented elsewhere (24). Dual-stained samples were
Downloaded by: NYU. Copyrighted material.
If a relationship exists between exercise training and decreased risk of URJ, a concomitant increase in NK cell activity would seem to be an important correlate. To investigate the effect of moderate exercise training on URI symptomatology and NK cell number and activity, we conducted a
mt. J. Sports Med. 11 (1990) 469
The Effects ofModerate Exercise Training on Natural Killer Table 1
Metabolic Parameters at Baseline, 6 weeks, and 15 weeks. (Means SE)
Baseline
Variable
HRstage2(bpm) HRmax (bpm)
162±3 183±2
2 (lmin 1) VEmax (Lmin1) VO2stage2 (mlkg1mint) VO2max (mlkg1min1)
53.7±1.9 81.8±2.7 21.1±0.4* 25.7±0.9
Exercise Group (N=18) 15 weeks 6 weeks 152
146 183
184±2 44.6 1.7t
44.1
85.3±2.4 19.2±0.3t 26.4±0.7
84.8±3.2 18.9±0.2t 26.3±0.7
1 .4t
Effect Group x Time
Nonexercise Group
(N=18) Baseline
6 weeks
15 weeks
p value
153±2
152±2
150±3
0.003
48.4± 1.8
47.8 1.9
47.4
81.1
85.1
19.3±0.3 25.0±0.9
19.0±0.2
88.2±2.8 18.8±0.2 24.7±0.9
25.1
1.8
The Effects of Moderate Exercise Training on Natural Kifier Cells and Acute Upper Respiratory Tract Infections D. C. Nieman, S. L. Nehlsen-Cannarel!a, P. A. Markoff A. J. Balk-Lamberton, H. Yang, D. B. W. Chritton, J. W. Lee, and K. Arabatzis Department of Health Science, School of Public Health Loma Linda University. Immunology Center, Loma Linda University Medical Center.
D. C. Nieman, S. L. Nehisen-Cannarella, P. A. Markoff A. J. Balk-Lamberton, H. Yang, D. B. W. Chrition, J. W. Lee, K. Arabatzis, The Effects of Moderate Exercise Training on Natural Killer Cells and Acute Upper Respira-
tory Tract Infections. Tnt J Sports Mcd, Vol 11, No 6, pp 467—473,1990.
Accepted after revision: February 12, 1990
A randomly controlled 1 5-wk exercise training (El) study (five 45-mm sessions/wk, brisk walking at 60% heart rate reserve) with a group of 36 mildly obese, sedentary women was conducted to investigate the relationship between improvement in cardiorespiratory fitness, changes in natural killer (NK) cell number and activity, and acute upper respiratory tract infection (URI) symptomatology. The study was conducted using a 2 (exercise and nonexercise groups) x 3 (baseline, 6-, and 1 5-wk testing sessions) factorial design, with data analyzed using repeated measures ANOVA. No significant change in NK cell number occurred as a result of ET as measured by the CD16 and Leu-19 nionoclonal antibodies. El did have a significant effect on NK cell activity (E:T 50:1) especially during the initial 6-wk period [F(2,68) = 12.34, p< 0.0011. Using data from daily logs kept by each subject, the exercise group was found to have significantly fewer URI symptom
days/incident than the nonexercise group (3.6±0.7 vs 7.0 1.4 days, respectively, p = 0.049). Improvement in cardiorespiratory fitness was correlated significantly with a
reduction in URI symptom days/incident (r = 0.37, p = 0.025) and a change in NK cell activity from baseline to six but not 15 wks (r 0.35, p= 0.036). In summary, moderate ET is associated with elevated NK cell activity after six
but not 15 weeks, and reduced URI symptomatology in comparison to a randomized, sedentary control group. Key words
exercise, upper respiratory tract infections, natural killer cell activity, immune system
Acute upper respiratory tract infections (URI) impose a significant burden each year in terms of days of disability, lost school or work days, and medical costs (23). The Centers for Disease Control has estimated that 429 million URI occur annually in the US resulting in $2.5 billion in direct costs (37). The 1987 US incidence rates per 100 persons per year for all acute respiratory conditions was 80.1, led by influenza (38.2) and the common cold (25.9) (23). There is a growing interest in the effects of both
acute and chronic exercise on immunosurveillance and host protection (14, 18—22, 26, 30, 33, 35, 40). Although it is generally believed that exercise training increases resistance to URI, little scientific evidence exists to support this contention. Most
studies have examined the effects of acute submaximal and maximal exercise on changes in immune system parameters and function, providing little direct evidence as to how these alterations affect resistance to URI. Few prospective studies have been conducted in this area, and none have utilized randomized sedentary control groups (35, 40).
A better understanding of the relationship between exercise and URI may be gained by investigating the effects of exercise training on natural killer (NK) cells and their
activity. NK cells, first discovered in the early 1970s, are unique in that they express spontaneous cytolytic activity against a variety of tumor and virus-infected cells (12, 41). Unlike T lymphocytes, NK cells do not require the involvement of major histocompatibility antigens to initiate cytotoxicity. NK cells account for 10— 15% of mononuclear cells in the peripheral blood, and have been observed to respond rapidly to foreign materials and initially control them until the antigen spe-
cific immune system begins to respond. Thus interest in NK cells and their activity has grown because they represent a major first line defense system against viral infection (17, 41).
Nearly all studies to date have measured the acute effect of exercise, both maximal (2, 6, 9, 16) and submaximal (1, 7, 29, 36), on NK cell activity and numbers. We are aware of only two prospective studies that have measured the effects of exercise training on resting NK cell activity in human subjects (5, 40). The studies arrived at different conclusions, with Crist et al. (5) reporting a significant increase in NK
mt. J. Sports Med. 11(1990)467—473 GeorgThieme Verlag StuttgartNew York
cell activity following three months of exercise training and Watson et al. (40) reporting a decrease. In randomized controlled studies utilizing mice, daily exercise training has been
Downloaded by: NYU. Copyrighted material.
Introduction
Abstract
D. C. Niemann eta!.
468 mt. J. Sports Med. 11(1990) associated with a considerable increase in NK cell activity (8) and improved resistance to infection (4). Pedersen et a!. (28)
reported increased levels of NK cell activity at rest in trained vs untrained males, and proposed that the constantly elevated NK cell activity may promote better resistance have
Sin (34) used to determine the percent body fat. Residual volume was measured with the Jaeger constant volume, variable pressure plethysmograph (Erich Jaeger, GmbH & Co.,
Wurzburg, FRD). Body mass index (BMI) was calculated using the formula kg/rn
against TJRI.
randomly controlled 15-week brisk walking study with a group of mildly obese, sedentary, premenopausal women. This type of subject was selected because women of this age have been reported to have the highest rates of URI among adults (23), and to experience considerable cardiorespiratory benefits from regimens of brisk walking (13).
Methods
Subjects
The methods for this study have been described elsewhere (24). A brief description of our methods will be summarized here. Fifty women were selected for this study
who met the following criteria: 25—45 years of age, mildly obese (10—40% overweight), premenopausal, 155—170cm in height, not presently on an exercise program or a reducing diet, a nonsmoker without a history of alcohol or drug abuse, no current use of medications (except oral contraceptives), absence of hypertension and diabetes, and no family history of heart disease. Those who qualified for the study were instructed that they would be randomly assigned to an exercise (EX) or nonexercise (NEX) group. All subjects agreed to accept their randomized placement preceding the study, and were blinded as to the aims of the study. Each subject voluntarily signed an informed consent statement approved by the
Loma Linda University Institutional Review Board for Human Studies.
Maximal graded exercise testing was conducted using the Bruce treadmill protocol on the Quinton Q4000 stress test system and Q55 treadmill (Quinton Instrument Co., Seattle, WA). Metabolic measurements were taken with the Sensor Medics MMC Horizon System 4400 metabolic cart (Sensor Medics, Anaheim, CA).
Exercise Program For 15 weeks the EX group followed a closely supervised walking program on a measured course. This consisted of five 45-mm sessions each week at an intensity of 60% of heart rate reserve. To ensure that the subjects exercised at a proper intensity, heart rates were monitored by checking pulse rates every 0.8 km. At the completion of 45 mm the supervisor recorded their walking distance to the nearest 0.16km. During the 15-week study, the NEX group was instructed not to participate in any exercise outside of normal daily activity.
Subject Recording of URI Symptoms Log books for daily recording of health problems and exercise patterns were given to each subject at baseline. Careful verbal and written instructions were given. Subjects recorded health problems each day of the 15-week study, using 10 codes utilized in a previous study by the Centers for Disease Control (11). The coded health problems included:
cold (runny nose, cough, sore throat), allergy (itchy eyes, stuffy nose), headache, fever, nausea/vomiting/diarrhea, fatigue/tiredness, muscle/joint/bone problem or injury, menstrual cramps, other (describe in blank), or none. URI was
defined when subjects coded for a cold with or without supporting symptoms of headache, fever, fatigue/tiredness,
or nausea/vomiting/diarrhea. An episode of URI was Experimental Design The 15-week research project extended from the last weekend of January to mid-May 1989. Testing was conducted at 3 time periods: baseline, 6 weeks, and 15 weeks. Since exercise training was conducted on weekdays, testing was peformed on Sundays to allow EX subjects a minimum of 36 h of recovery from the last exercise session.
deemed to have commenced if symptoms were coded for a minimum of 48 h and separated by at least one week from a previous episode. Mode of exercise was recorded using 25 coded activities with duration and/or distance reported with each.
Blood Analysis Heparinized whole blood was used for NK cell
All subjects reported to the Loma Linda University Human performance Lab for testing at 0700 h following 12 h of fasting. After resting for at least 5 mm, blood samples were collected. Subjects returned throughout the day for assessment of the following: height and weight, body com-
number and activity assays and EDTA whole blood for
position (hydrostatic weighing and 7-site skinfold tests),
Peripheral blood lymphocytes were isolated by Ficoll-Hypaque centrifugation. Using direct immuno-
resting 12-lead EKG, and 12-lead EKG graded exercise testing with metabolic measurements. If a subject exhibited overt symptoms of URI, the appointment was rescheduled.
Body Composition and Treadmill Testing Body density was determined by hydrostatic weighing, as outlined by Pollock et al. (31), with the formula of
complete blood counts (CBC). CBC were performed on Coulter S-Plus IV instrumentation with visual cell differentials in our clinical hematology laboratory.
fluorescence staining of cell surfaces in lysed whole blood with
mouse anti-human monoclonal antibodies (mAb) from Becton Dickinson Immunocytometry Systems (Mountain View, CA), we analyzed the blood samples for NK cells (CD 16 and Leu-19 [CD undesignated]). Blood samples were also analyzed for other lymphocyte subpopulations, data which are being presented elsewhere (24). Dual-stained samples were
Downloaded by: NYU. Copyrighted material.
If a relationship exists between exercise training and decreased risk of URJ, a concomitant increase in NK cell activity would seem to be an important correlate. To investigate the effect of moderate exercise training on URI symptomatology and NK cell number and activity, we conducted a
mt. J. Sports Med. 11 (1990) 469
The Effects ofModerate Exercise Training on Natural Killer Table 1
Metabolic Parameters at Baseline, 6 weeks, and 15 weeks. (Means SE)
Baseline
Variable
HRstage2(bpm) HRmax (bpm)
162±3 183±2
2 (lmin 1) VEmax (Lmin1) VO2stage2 (mlkg1mint) VO2max (mlkg1min1)
53.7±1.9 81.8±2.7 21.1±0.4* 25.7±0.9
Exercise Group (N=18) 15 weeks 6 weeks 152
146 183
184±2 44.6 1.7t
44.1
85.3±2.4 19.2±0.3t 26.4±0.7
84.8±3.2 18.9±0.2t 26.3±0.7
1 .4t
Effect Group x Time
Nonexercise Group
(N=18) Baseline
6 weeks
15 weeks
p value
153±2
152±2
150±3
0.003
48.4± 1.8
47.8 1.9
47.4
81.1
85.1
19.3±0.3 25.0±0.9
19.0±0.2
88.2±2.8 18.8±0.2 24.7±0.9
25.1
1.8
