The effect of aerobic exercise on neutrophil functions.

PURPOSE: Intense exercise bouts are associated with a reduction of immune function and increased susceptibility to infections. Neutrophils act as a first line of defense to eliminate infectious agents and are also involved in muscle tissue inflammatory response to exercise. Intensive exercise suppresses several neutrophil functions including chemotaxis. The study investigates the pathophysiological mechanisms of impaired chemotaxis after submaximal aerobic exercise. METHODS: Twenty-three healthy physically active adult males were tested before and 24 h after 30 min of treadmill running at 75% VO2max. N-formyl-Met-Leu-Phe (fMLP)-stimulated neutrophil migration, polarization, adherence, expression of adhesion molecules (CD11b/CD18), and chemotactic receptor (C5aR) were assessed preexercise and postexercise. RESULTS: Neutrophil chemotaxis and polarization were found to be impaired 24 h postexercise. Adherence was impaired 24 h postexercise as well, but the expression of the adhesion molecule CD11b/CD18 was not affected. Further, the availability of the C5aR was found to be unaffected 24 h postaerobic exercise. CONCLUSIONS: The pathophysiological mechanism of the impaired chemotaxis is likely related to the impaired postexercise neutrophil adherence and polarization but not to changes in the chemotactic receptor availability.

The effect of pre-test carbohydrate ingestion on the anaerobic threshold, as determined by the lactate-minimum test.

The purpose of this study was to investigate the effect of pre-test carbohydrate (CHO) ingestion on anaerobic-threshold assessment using the lactate-minimum test (LMT). Fifteen competitive male distance runners capable of running 10 km in 33.5-43 min were used as subjects. LMT was performed following CHO (2x300 mL, 7% solution) or comparable placebo (Pl) ingestion, in a double-blind, randomized order. The LMT consisted of two high-intensity 1 min treadmill runs (17-21 km.h(-1)), followed by an 8 min recovery period. Subsequently, subjects performed 5 min running stages, incremented by 0.6 km.h(-1) and separated by 1 min blood-sampling intervals. Tests were terminated after 3 consecutive increases in blood-lactate concentration ([La]) had been observed. Finger-tip capillary blood was sampled for [La] and blood-glucose determination 30 min before the test's onset, during the recovery phase following the 2 high-intensity runs, and following each of the subsequent 5 min stages. Heart rate (HR) and rating of perceived exertion (RPE) were recorded after each stage. The lactate-minimum speed (LMS) was determined from the individual [La]-velocity plots and was considered reflective of the anaerobic threshold. Pre-test CHO ingestion had no effect on LMS (13.19+/-1.12 km.h(-1) vs. 13.17+/-1.08 km.h(-1) in CHO and Pl, respectively), nor on [La] and glucose concentration at that speed, or on HR and RPE responses. Pre-test CHO ingestion therefore does not affect LMS or the LMT-estimated anaerobic threshold.

Daily physical activity and perception of condition severity among male and female adolescents with congenital heart malformation.

The purpose of this study was to examine among young patients with congenital heart malformation (CHM) the concordance between a cardiologist's definition of the severity of malformation and recommendations regarding physical activity and the patients' perceptions of their condition. Subjects included male (n = 55) and female (n = 45) adolescents aged between 12 and 18 years who have trivial (38%), mild (21%), or moderate (41%) CHM. Thirty-one percent of the patients rated their CHM as less severe whereas 15% rated their CHM as more severe than the cardiologist's definition. Although most patients engaged in physical activity appropriate for their condition, a noteworthy percentage engaged in activities more intense than those recommended by the patient's personal cardiologist.

Effect of low altitude at the Dead Sea on exercise capacity and cardiopulmonary response to exercise in cystic fibrosis patients with moderate to severe lung disease.

Oxygen supplementation may improve exercise tolerance and the physiological response to exercise in cystic fibrosis (CF) patients. Elevated barometric pressure at low altitude is a simple means of increasing the quantity of inspired oxygen. Our objectives were to examine the effect of natural oxygen enrichment (at the Dead Sea, 396 m below sea level) on exercise capacity, and the physiological responses to maximal and submaximal exercise in CF patients. Patients were tested twice: at sea level (barometric pressure, 754 +/- 6 mmHg, mean +/- SD), and at the Dead Sea (barometric pressure, 791 +/- 3 mmHg), in a randomized crossover design. We studied 14 CF patients (6 females, 8 males), aged 15-45 years, with moderate to severe lung disease (mean forced expired volume in 1 sec = 50.0 +/- 11.2% predicted). Tests at each site included resting spirometry, anthropometry, a graded submaximal exercise test, a maximal exercise test on a treadmill, and a 6-min walk test. Tests were performed in identical order at both sites. Tests at the Dead Sea were performed 72 hr after arrival. No differences between sites were observed in lung function at rest. Peak oxygen consumption was significantly improved at the Dead Sea compared with sea level (1.68 +/- 0.73 vs. 1.57 +/- 0.74 l/min, respectively, P = 0.05), along with an improvement in the ventilatory equivalent for oxygen (41.2 +/- 6.3 vs. 46.1 +/- 7.1, respectively, P < 0.05). During submaximal exercise, blood oxygen saturation improved at the Dead Sea compared with sea level at all exercise intensities (P < 0.05). In conclusion, these results suggest that even a brief stay at the Dead Sea area may have physiological benefits for CF patients with moderate to severe lung disease.

Exercise with and without an insulin pump among children and adolescents with type 1 diabetes mellitus.

BACKGROUND: The use of insulin pumps is becoming a popular technique for insulin delivery among patients with type 1 diabetes mellitus (T1DM), but there is no consensus regarding the guidelines for proper pump use during exercise. OBJECTIVE: To investigate the physiologic responses and risk of hypoglycemia among children and adolescents with T1DM when exercising with the pump on (PO) (50% of the basal rate) or pump off (PF). METHODS: Ten subjects with T1DM (6 female subjects and 4 male subjects), 10 to 19 years of age, performed prolonged exercise (40-45 minutes) on a cycle ergometer approximately 2 hours after a standard breakfast and an insulin (Lispro) bolus. Complex carbohydrates (20 g) were provided before and after the exercise. Each patient exercised once with PO and once with PF, in a randomized, crossover (single-blind) manner. During exercise and 45 minutes of recovery, subjects were monitored for cardiorespiratory, metabolic, and hormonal responses. Blood glucose concentrations were recorded for 24 hours after exercise, with a continuous glucose monitoring system, to document late hypoglycemic events. RESULTS: During exercise, blood glucose concentrations decreased by 59 +/- 58 mg/dL (mean +/- SD: 29 +/- 24%) with PF and by 74 +/- 51 mg/dL (35.5 +/- 18%) with PO (not significant). No significant differences were found in cortisol, growth hormone, or noradrenaline levels between PO and PF. There were no differences in cardiorespiratory parameters, blood lactate concentrations, or free fatty acids concentrations between pump modes. Hypoglycemic events during exercise were asymptomatic and occurred for 2 subjects with PO and 2 with PF. Nine subjects had late hypoglycemia after PO, compared with 6 after PF (not significant). CONCLUSIONS: We found no advantage for subjects with either PO or PF during exercise, and we noted that late hypoglycemia was more common than hypoglycemia during exercise. However, PO was associated with a trend of increased risk for late hypoglycemia. We recommend that the pump be removed or turned off during prolonged exercise and that blood glucose concentrations be monitored for several hours after exercise, regardless of the pump mode.

Transient decrease of neutrophil chemotaxis following aerobic exercise.

PURPOSE: Intense exercise affects the immune system, increasing the susceptibility of athletes to viral and bacterial infections. We have previously shown a significant decrease of fMLP-neutrophil migration 24 h after aerobic exercise. In this study we aimed to look at the differential effect of different chemoattractants on neutrophil migration following aerobic exercise, to determine the recovery time, and to better understand the role of the cell skeleton behind the impaired chemotaxis. METHODS: Sixteen female volunteers aged 22-30 yr were tested before, 24, and 48 h after aerobic exercise (30 min running at 70% (.)VO(2max). The submaximal exercise test was conducted a week after the (.)VO(2max) test. We studied the membrane cell receptor response to fMLP, IL-8, and C5a, which have specific ligand-receptor pathways. Further, we studied the cytoskeletal response by investigating the cell polarization and the F-actin polymerization. RESULTS: Significant decrease of the neutrophil net chemotaxis was detected with fMLP, IL-8 and C5a, 24 h after exercise (50 +/- 5%, P = 0.0001; 48 +/- 12%, P = 0.0015; and 32 +/- 11%, P = 0.011, respectively). Complete recovery was observed within 48 h with all chemoattractants. Normal neutrophil random migration and F-actin polymerization were found. Decreased neutrophil polarization was detected (46 +/- 6% vs 22 +/- 8% of polarized cells, before and after effort, respectively; P = 0.004). Correlation between polarization and chemotactic migration was found (r = 0.945; P = 0.001). CONCLUSIONS: The impaired chemotactic response, observed 24 h after exercise, was similar using different chemoattractants. This finding indicates a possible exercise-induced effect on a common factor at the ligand-receptor level. The abnormal cell polarization indicates skeletal dysfunction that should be further investigated and elucidated. The normal fMLP-stimulated-F-actin polymerization reflects an adequate pathway of signal transduction for the formyl peptide.

Effect of lycopene supplementation on lung function after exercise in young athletes who complain of exercise-induced bronchoconstriction symptoms.

BACKGROUND: It has been suggested that exercise-induced bronchoconstriction may involve oxidative stress. Strenuous exercise promotes free radical production, which can lead to many of the pathophysiologic changes associated with asthma, including bronchoconstriction, mucus secretion, and microvascular leakage. Lycopene has been shown to have high antioxidative activity. OBJECTIVE: To evaluate the effect of lycopene supplementation on airway hyperreactivity and inflammation in young athletes who complain of difficulty in breathing related to physical exertion. METHODS: Nineteen young athletes with exercise-related difficulty in breathing visited the exercise laboratory 3 times. During the first visit, participants underwent a baseline evaluation of exercise-induced bronchoconstriction. Daily for 1 week before each of the 2 subsequent visits, participants ingested 30 mg of lycopene (a natural antioxidant) or placebo (in randomized order, double-blind). A 2-week washout period was given between each visit. During each visit, lung functions were evaluated before and after an 8-minute run on the treadmill (85% of the predicted maximal heart rate). RESULTS: There was no difference in the mean+/-SD decrease in forced expiratory volume in 1 second after exercise during lycopene treatment compared with placebo treatment (11.8%+/-12.5% and 11.0%+/-11.6%). In addition, there was no apparent division into responders and nonresponders. CONCLUSION: A daily dose of lycopene for 1 week does not affect lung function after exercise and may not provide any protective effect against clinical difficulty in breathing in young athletes.

Quantitative ultrasound of the tibia and radius in prepubertal and early-pubertal female athletes.

BACKGROUND: Physical exercise during childhood has been shown to enhance bone mineral density, thus reducing the risk of osteoporosis. OBJECTIVE: To examine bone properties, as measured by quantitative ultrasound, in prepubertal and early-pubertal female athletes engaged in impact and nonimpact sports. DESIGN: Survey. SETTING: General community. PARTICIPANTS: Twenty-five acrobatic gymnasts, 21 swimmers, and 21 control subjects. Athletes had been training for at least 1(1/2) years. MAIN OUTCOME MEASURE: Bone speed of sound (bilateral) at the distal radius and the midtibia. RESULTS: Gymnasts were significantly shorter and lighter than swimmers and control girls (P<.001) but had a body mass index similar to that of swimmers. Adiposity was lower in athletes than in controls. Speed of sound did not correlate with measures of body size. Higher mean +/- SD radial speed of sound values (nondominant side) were observed in gymnasts (3764 +/- 104 m/s; P =.045) than in swimmers and control girls (3732 +/- 99 and 3721 +/- 83 m/s, respectively). Mean +/- SD tibial speed of sound values (nondominant side) were similar in gymnasts and swimmers (3629 +/- 87 and 3619 +/- 78 m/s, respectively) and higher in the athletic groups than in the control group (3516 +/- 127 m/s; P<.001). In all 3 groups, no differences were observed between dominant and nondominant sides in the radii or tibias. CONCLUSIONS: Physical exercise, impact and nonimpact, is related to enhanced bone properties, as measured by quantitative ultrasound. Longitudinal studies using various modes of bone evaluation are necessary to determine the long-term effect of various types of exercise on bone properties.

Weight gain associated with increased food intake and low habitual activity levels in male adolescent schizophrenic inpatients treated with olanzapine.

OBJECTIVE: The authors studied weight gain mechanisms and energy balance in patients treated with olanzapine. METHOD: The body mass index of male schizophrenic adolescent inpatients treated with olanzapine (N=10) and of 10 matched patients treated with haloperidol (N=10) were measured at baseline and after 4 weeks of treatment. For the patients treated with olanzapine, caloric intake, resting energy expenditure, and physical activity (determined through accelerometry and heart rate monitoring) were assessed at baseline and after 4 weeks of treatment. RESULTS: Body mass index significantly increased in those treated with olanzapine but not in those given haloperidol. The increase in body mass index was due to an increase in caloric intake without change in diet composition. Olanzapine had no significant effect on resting energy expenditure. Daily energy expenditure was very low before and after treatment. CONCLUSIONS: Olanzapine-induced weight gain is associated with a general increase in caloric intake.