Increased training load and the beta-adrenergic-receptor system on human lymphocytes

Immune Response of Elite Enduro Racers to Laboratory and Racing Environments: The Influence of Training Impulse and Vibration

Introduction: Understanding the sport-specific immune response elicited during both training and competition is imperative to maximise athlete health and performance. Despite a growing population of professional enduro mountain bike athletes, little is known about the recovery of the immune system following enduro racing events. Methods: Nine international level elite enduro mountain bike athletes (age 24.3 ± 2.4 years, height 178.5 ± 8.7 cm, mass 76.5 ± 12.5 kg) completed a laboratory-based maximal exercise test (LAB) on a cycle ergometer and competed in an international mountain bike enduro race event (RACE). Blood samples were taken before, immediately after, and 1 h after LAB and before, 1 h after, and 17 h after RACE. Leukocyte subsets were enumerated using seven-colour flow cytometry. Lucia’s training impulse (LuTRIMP) and vibration exposure (VIB) were quantified during RACE. Results: Seven participants were included in the final analyses. There was a significant (p < 0.05) increase in neutrophil count alongside a reduction of cytotoxic lymphocyte cell subsets of both the innate (CD3⁻/CD56⁺ NK-cells and CD3⁻/CD56^dim NK-cells) and adaptive (CD8⁺/CD62L⁻/CD45RA⁻ T-cells and CD8⁺/CD27⁺/CD28⁻ T-cells) components of the immune system one hour after RACE. All cell counts returned to baseline values 17 h afterwards (p > 0.05). Cell subset redistribution from pre- to post-one-hour time points (%Δpre-post1h) in cell subsets with potent effector functions (Neutrophils, CD3⁻/CD56⁺ NK-cells, CD8⁺/CD62L⁻/CD45RA⁻ T-cells, CD8⁺/CD27⁺/CD28⁻ T-cells, and CD3⁻/CD56^dim/CD57⁻ NK-cells) was significantly greater at RACE than LAB (p < 0.05). VIB was shown to be a superior predictor of %Δpre-post1h CD4⁺ T-cells, CD4⁺ early T-cells, CD4⁺ naïve T-cells, and NK cells as compared with LuTRIMP on its own (ΔR² = 0.63 − 0.89, p < 0.05). Conclusions: The race event offers a greater challenge to the immune system than LAB, and potentially, whole body vibration is a key component of training load measurement in mountain bike applications.

Leukocyte β2-adrenergic receptor expression in response to resistance exercise

PURPOSE

Epinephrine and norepinephrine mediate interactions between the neuroendocrine and the immune systems to alter immune cell activity. Although both systems respond to exercise stress, less is known about how they interact in response to such stress. The purpose of this investigation was to examine β2-adrenergic receptor (β2-ADR) expression on circulating leukocytes to an acute bout of resistance exercise in men and women.

METHODS

Resistance-trained men (n = 8; mean ± SD age = 24.63 ± 5.07 yr, body mass index = 26.09 ± 2.21 kg·m(-2)) and women (n = 7; age = 22.13 ± 3.09 yr, body mass index = 22.63 ± 2.03 kg·m(-2)) performed an acute resistance exercise protocol (six sets of five-repetition maximum heavy squats) and a control test (i.e., identical conditions with no exercise) in a balanced, randomized order. Using a within-subject design, β2-ADR expressions on circulating leukocytes were evaluated with flow cytometry, and plasma epinephrine and norepinephrine were evaluated with high-performance liquid chromatography.

RESULTS

Plasma epinephrine and norepinephrine increased during the exercise bout and returned to baseline during recovery. β2-ADR expression on monocytes was elevated in anticipation of the exercise protocol. β2-ADR expression on monocytes and granulocytes decreased during the exercise. β2-ADR expression on lymphocytes was elevated during the recovery time points.

CONCLUSIONS

In conclusion, β2-ADR expression on leukocyte subpopulations changes in response to acute heavy resistance exercise protocol. The present findings provide insights into the potential temporal interactions between the neuroendocrine and the immune systems in response to the physiological stress of acute heavy resistance exercise in men and women.

Freewheel training decreases pro- and increases anti-inflammatory cytokine expression in mouse intestinal lymphocytes

Intestinal inflammation and inflammatory bowel diseases (IBD) may occur due to imbalances in pro- and anti-inflammatory cytokines. Long-term exercise reduces the risk for IBD. The purpose of this study was to determine the effect of long-term wheel running in healthy mice on intestinal lymphocyte (IL) expression of pro- and anti-inflammatory cytokine proteins. In addition, pro- and anti-apoptotic proteins and the percentage of early apoptotic, late apoptotic, and dead IL were measured with wheel running and following acute aerobic exercise. Female C57BL/6 mice were given 16 weeks of wheel running (WR) or a control condition (No WR) and at the end of training were assigned to a single acute treadmill exercise session with sacrifice immediately, 2h after, or 24h after completion of exercise, or were not run (sedentary) with respect to the acute treadmill exercise. Intestinal lymphocytes were assessed for pro-(TNF-α, IL-17) and anti-(IL-10) inflammatory, and pleiotropic (IL-6) cytokines, and pro-(caspase 3 and 7, AIF) and anti-(Bcl-2) apoptotic protein expression. The percent of early (Annexin(+)) and late (Annexin(+)PI(+)) apoptotic, and dead (PI(+)) IL was determined. WR mice had lower TNF-α and caspase 7, and higher IL-10 and IL-6 expression in IL than No WR mice. A single exposure to intense aerobic treadmill exercise increased pro-(TNF-α) and anti-(IL-10) inflammatory cytokine and pro-apoptotic protein (caspase 3) expression in IL. The percent of early and late apoptotic, and dead IL were higher after acute exercise. Although long-term voluntary wheel running did not protect against acute exercise-induced changes in IL cytokine expression or apoptosis, there was an overall 'anti-inflammatory' effect observed as a result of wheel running in healthy mice.

Plasma β-endorphin, cortisol and immune responses to acute exercise are altered by age and exercise training in horses

REASONS FOR PERFORMING STUDY

Ageing appears to affect immune and neuroendocirne function in horses and response to acute exercise. No studies have examined the combined effects of training and ageing on immune and neuroendocirne function in horses.

HYPOTHESIS

To ascertain whether training and age would affect the plasma beta-endorphin (BE) and cortisol (C) as well as immune function responses to acute exercise in Standardbred mares.

METHODS

Graded exercise tests (GXT) and simulated race tests (SRT) were performed before and after 12 weeks training at 60 % HRmax. BE and C were measured at rest and at 5, 10, 20, 40, 60 and 120 min post GXT. Leucocyte cell number, CD4+ and CD8+ lymphocyte subsets, and mitogen stimulated lymphoproliferative response (LPR), were measured in jugular blood before and after the SRTs.

RESULTS

Cortisol rose by 5 min post GXT in young (Y) and middle-age (MA) mares (P<0.05) and remained elevated until 40 and 60 min post GXT, respectively during both pre- and post training GXT. There was no rise in C in old (0) mares after either GXT (P>0.05). Pretraining BE rose (P<0.05) by 5 min post GXT in all mares. After training, BE was higher in Y and O vs. MA (P<0.05) at 5 min post GXT. Post training BE was higher at 5 min post GXT in Y and O vs. pretraining (P<0.05). After SRT, lymphocyte number rose in all mares (P<0.05); however, lower lymphocyte numbers (P<0.05) were seen in MA vs. Y and O vs. MA (P<0.05). The O had reduced LPR to Con A and PHA stimulation (P<0.05) compared to Y and MA after the SRT after both pre- and post training SRT. LPR to PWM was lower (P<0.05) in O vs. Y and MA after the pretraining SRT. Training caused an increase in resting LPR to PWM in MA only (P<0.05).

CONCLUSION

Both age and training altered the plasma beta-endorphin and cortisol responses as well as and immune responses to acute exercise.

POTENTIAL RELEVANCE

This study provides important information on the effects of ageing and training that will aid in the management and care of an increasing number of active older horses.

The effects of chronic aerobic and anaerobic exercises n lymphocyte subgroups

Exercise is the strongest stress to which the body is ever exposed. The body responds to this stress through a set of physiological changes in its metabolic, hormonal and immunological systems. In this study, responses of the immune system to the long-term aerobic and anaerobic exercises have been investigated. Twenty-four sedentary male university students and officers participated in this study. Subjects were divided into two groups, each consisting of twelve people. Group-1 (age: 25.67 +/- 3.79 years, height: 174.83 +/- 5.15 cm, body mass: 72.17 +/- 8.05 kg) and Group-2 (age: 24.83 +/- 2.89 years, height: 175.3 +/- 6.68 cm, body mass: 70.67 +/- 6.15 kg). After physical examinations of the two groups, resting ECG, respiratory function tests and metabolic tests with the use of the breath by breath method were completed, and anerobic heart rates at the threshold level were determined. The first group was subjected to exercise using Monark ergometry cycles at a heart rate 10% below the threshold level for 8 weeks, 3 days a week, 30 min a day. The second group exercised at a heart rate 10% above the threshold level for 8 weeks, 3 days a week, 20 min a day. Heart rates were checked with the Polar Test during exercises. Pre-exercise (Ep) venous blood samples were taken from each group before their 1st and 24th exercises. Hb (gr), Hct (%), erythrocyte (x10(6)/microl), leukocyte (x10(6)/microl), leukocyte subpopulations (neutrophil, lymphocyte, monocyte, eosinophil, basophil %) and thrombocyte (x10(6)/microl) values were determined. CD3, CD4, CD8, CD19 and CD56 values were determined by Flow Cytometry method using monoclonal antibodies. The chronic effects of exercise were examined through a comparison of Ep blood samples at the 1st exercise with Ep blood samples at the 24th exercise. While the increase in the total leukocyte number was significant (p<0.05) in the first group, increase in the second group was found to be non-significant. When percentiles of leukocyte subpopulations were taken into consideration, changes in the first and second group were found to be non-significant. When lymphocyte subgroups were examined; in the first group a decrease in CD3 and CD4 percentiles to 7% and 12%, respectively (p<0.05) and a 65% increase (p<0.01) in the CD56 value were observed. In the second group a decrease in CD3 and CD4 percentiles to 13% and 17%, respectively (p<0.05) and a 73% increase (p<0.01) in the CD56 value were observed. The Sample-t Test and The Wilcoxon Test were used for statistical analysis.

Effects of exercise and ischemia on mobilization and functional activation of blood-derived progenitor cells in patients with ischemic syndromes: results of 3 randomized studies

BACKGROUND

Exercise training (ET) has been shown to improve regional perfusion in ischemic syndromes. This might be partially related to a regeneration of diseased endothelium by circulating progenitor cells (CPCs) or CPC-derived vasculogenesis. The aim of the present study was to determine whether ischemic stimuli during ET are required to promote CPC mobilization in patients with cardiovascular diseases.

METHODS AND RESULTS

Patients with peripheral arterial occlusive disease (PAOD) were randomized to 4 weeks of daily ischemic ET or control (group A). Successfully revascularized patients with PAOD were randomized to 4 weeks of daily nonischemic ET or control (group B). Patients with stable coronary artery disease were subjected to 4 weeks of subischemic ET or control (group C). At baseline and after 4 weeks, the number of KDR+/CD34+ CPCs was determined by fluorescence-activated cell sorting analysis. Levels of vascular endothelial growth factor (VEGF) were measured by ELISA. A Matrigel assay was used to quantify CPC integration into vascular structures. Expression of the homing factor CXCR4 was determined by reverse transcription-polymerase chain reaction. In group A only, ischemic ET increased VEGF levels by 310% (P<0.05 versus control) associated with an increase in CPCs by 440% (P<0.05 versus control), increased CXCR4 expression, and enhanced integration of CPCs into endothelial networks. In contrast, subischemic ET in groups B and C increased CXCR4 expression and CPC integration.

CONCLUSIONS

In training programs, symptomatic tissue ischemia seems to be a prerequisite for CPC mobilization. However, ischemic and subischemic ET programs affect CXCR4 expression of CPCs, which might lead to an improved CPC integration into endothelial networks.

Effect of chronic clenbuterol administration and exercise training on immune function in horses

Effects of longitudinal exercise training and acute intensive exercise (simulated race test) on immune function have not been reported in horses. Clenbuterol, a beta2-adrenergic agonist, is used to manage inflammatory airway disease in horses. This study investigated the interaction of 8 wk of exercise training with or without 12 wk of clenbuterol administration in horses. Twenty-three untrained standardbred mares (10 +/- 3 yr, Mean +/- SE) were used and divided into four experimental groups. Horses given clenbuterol plus exercise (CLENEX; n = 6) and clenbuterol alone (CLEN; n = 6) received 2.4 microg/kg BW of clenbuterol twice daily (in an average volume of 20 mL) on a schedule of 5 d on and 2 d off for 12 wk. The CLENEX group was also aerobically trained 3 d/wk. Mares given exercise alone (EX; n = 5) were aerobically trained for 3 d/wk, and the control group (CON; n = 6) remained sedentary. Both EX and CON horses were administered similar volumes (approximately 20 mL) of molasses twice daily. A simulated race test (SRT) resulted in an elevation in lymphocyte number postexercise (P < 0.05). There was no significant difference after acute exercise in either monocyte or granulocyte number. Acute exercise resulted in a decrease (P < 0.05) in the percentage of CD4+ and an increase (P < 0.05) in the percentage of CD8+ cells. The SRT resulted in a decreased lymphoproliferative response to pokeweed mitogen (P < 0.05). A SRT had no effect on antibody production in response to equine influenza vaccine. The EX group demonstrated greater cortisol concentrations at rest and at all other time points postexercise after completing the training regimen compared with CLENEX horses (P < 0.05). Preexercise (SRT) peripheral blood monocyte number was lower in CLENEX horses than in other treatment groups (P < 0.05). Clenbuterol and exercise training did not significantly affect post-SRT changes in leukocyte numbers. Exercise training resulted in a decrease (P < 0.05) in the percentage of CD8+ cells post-SRT compared with other groups, but the percentage of CD4+ cells was not altered by either clenbuterol or exercise conditioning. Lymphocyte proliferative response was not affected by clenbuterol or exercise treatment. Horses demonstrated responses to bouts of acute exercise as noted with other species, namely humans and rodents.

Effects of carbohydrate supplementation on performance and carbohydrate oxidation after intensified cycling training

To study the effects of carbohydrate (CHO) supplementation on performance changes and symptoms of overreaching, six male endurance cyclists completed 1 wk of normal (N), 8 days of intensified (ITP), and 2 wk of recovery training (R) on two occasions in a randomized crossover design. Subjects completed one trial with a 6% CHO solution provided before and during training and a 20% solution in the 1 h postexercise (H-CHO trial). On the other occasion, subjects consumed a 2% CHO solution at the same time points (L-CHO). A significant decline in time to fatigue at ∼63% maximal power output (H-CHO: 17 ± 3%; L-CHO: 26 ± 7%) and a significant increase in mood disturbance occurred in both trials after ITP. The decline in performance was significantly greater in the L-CHO trial. After ITP, a significant decrease in estimated muscle glycogen oxidation (H-CHO: N 49.3 ± 2.9 kcal/30 min, ITP 32.6 ± 3.4 kcal/30 min; L-CHO: N 49.1 ± 30 kcal/30 min, ITP 39.0 ± 5.6 kcal/30 min) and increase in fat oxidation (H-CHO: N 16.3 ± 2.4 kcal/30 min, ITP 27.8 ± 2.3 kcal/30 min; L-CHO: N 16.9 ± 2.6 kcal/30 min, ITP: 25.4 ± 3.5 kcal/30 min) occurred alongside significant increases in glycerol and free fatty acids and decreases in free triglycerides in both trials. An interaction effect was observed for submaximal plasma concentrations of cortisol and epinephrine, with significantly greater reductions in these stress hormones in L-CHO compared with H-CHO after ITP. These findings suggest that CHO supplementation can reduce the symptoms of overreaching but cannot prevent its development. Decreased endocrine responsiveness to exercise may be implicated in the decreased performance and increased mood disturbance characteristic of overreaching.

Acute exercise alters Gαi2 protein expressions through the ubiquitin–proteasome proteolysis pathway in rat adipocytes

The effects of acute exercise on the protein expressions of heterotrimeric G protein alpha subunits were examined in rat adipocytes. Galphai2 protein expression was significantly reduced 0 and 3h after exercise but increased 24h after exercise, without alterations in Galphai2 mRNA expressions. The protein expressions of other alpha subunits, Galphas, Galphai1, and Galphai3, were not influenced. Both the 26S proteasome activity and polyubiquitination of Galphai2 protein were significantly increased 0 and 3h after exercise. Whereas, proteasome activity was decreased, and the polyubiquitination of Galphai2 protein was returned to the control level 24h after exercise. The reductions in Galphai2 protein expressions 0 and 3h after exercise were completely prevented by the injection either of a proteasome inhibitor or of a beta-adrenergic receptor blocker prior to exercise. Thus, acute exercise altered the expression of Galphai2 protein via mechanisms which involve the coupling of beta-adrenergic receptors to an agonist with subsequent ubiquitin-proteasome-dependent proteolysis.

Exercise training-induced adaptations of immune response are mediated by β-adrenergic receptors in aged but not young mice

β-Adrenergic blockade was used to determine whether the exercise training-induced adaptations of immune response to viral infection were mediated by catecholamines in young and old mice. Young (2 mo) and older (16 mo) male BALB/c mice were randomly assigned to an exercise or control group, and half of the mice in each group received the β-adrenergic receptor antagonist nadolol. After 8 wk of moderate exercise training, mice were challenged with herpes simplex virus (HSV) 24 h postexercise. The results showed that exercise treatment increased anti-HSV IgM antibody, enhanced IL-10, and altered the kinetics of IFN-γ and IL-2 production in young and old mice. Unique to older mice, exercise decreased mitogen-induced proliferation, increased splenocytes, and tended to decrease memory cells (CD44hi+). In contrast, exercise increased mitogen-induced proliferation but decreased the number of splenic lymphocyte and CD4+ cells in young mice. β-Adrenergic blockade blunted the exercise-induced changes in anti-HSV IgM, IL-2, IFNγ, and mitogen-induced proliferation in old but not young mice. The findings suggest that some of the immunomodulatory effects of chronic exercise are mediated via β-adrenergic receptors and that the role of β-adrenergic receptors is age dependent.

Special feature for the Olympics: effects of exercise on the immune system: overtraining effects on immunity and performance in athletes

Overtraining is a process of excessive exercise training in high-performance athletes that may lead to overtraining syndrome. Overtraining syndrome is a neuroendocrine disorder characterized by poor performance in competition, inability to maintain training loads, persistent fatigue, reduced catecholamine excretion, frequent illness, disturbed sleep and alterations in mood state. Although high-performance athletes are generally not clinically immune deficient, there is evidence that several immune parameters are suppressed during prolonged periods of intense exercise training. These include decreases in neutrophil function, serum and salivary immunoglobulin concentrations and natural killer cell number and possibly cytotoxic activity in peripheral blood. Moreover, the incidence of symptoms of upper respiratory tract infection increases during periods of endurance training. However, all of these changes appear to result from prolonged periods of intense exercise training, rather than from the effects of overtraining syndrome itself. At present, there is no single objective marker to identify overtraining syndrome. It is best identified by a combination of markers, such as decreases in urinary norepinephrine output, maximal heart rate and blood lactate levels, impaired sport performance and work output at 110% of individual anaerobic threshold, and daily self-analysis by the athlete (e.g. high fatigue and stress ratings). The mechanisms underlying overtraining syndrome have not been clearly identified, but are likely to involve autonomic dysfunction and possibly increased cytokine production resulting from the physical stress of intense daily training with inadequate recovery.

Interleukin-6 and tumor necrosis factor-alpha production after acute psychological stress, exercise, and infused isoproterenol: differential effects and pathways

OBJECTIVE

The aim of the study was to assess the effects of three different methods of acute activation of the sympathetic nervous system on lipopolysaccharide-induced in vitro production of interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha).

METHODS

Thirty-two healthy volunteers performed speech and exercise tasks and underwent a 30-minute infusion of isoproterenol.

RESULTS

As expected, acute activation of the sympathetic nervous system led to leukocytosis, including increases in lymphocyte, monocyte, and granulocyte populations (p values <.05). Lipopolysaccharide-induced IL-6 production was increased after both the speaking and exercise tasks (p values <.001), whereas TNF-alpha production was elevated only after exercise (p<.05). In contrast, infusion of isoproterenol inhibited TNF-alpha production (p<.001) and caused no change in IL-6 production.

CONCLUSIONS

In response to the challenges, IL-6 and TNF-alpha production showed different profiles. Purely beta-agonist stimulation led to downregulation of TNF-alpha production, providing evidence of the antiinflammatory effect of in vivo beta-receptor activation. The enhanced production of both cytokines after exercise, and of IL-6 after the speech task, can be best explained by a simultaneous upregulation of proinflammatory and inflammation-responding mediators. These effects may have an important role in controlling the immune response to acute psychological and physical stress.