Strenuous bouts of prolonged exercise and heavy training are associated with depressed immune cell function. Furthermore, inadequate or inappropriate nutrition can compound the negative influence of heavy exertion on immunocompetence. Dietary deficiencies of protein and specific micronutrients have long been associated with immune dysfunction. An adequate intake of iron, zinc and vitamins A, E, B6 and B12 is particularly important for the maintenance of immune function, but excess intakes of some micronutrients can also impair immune function and have other adverse effects on health. Immune system depression has also been associated with an excess intake of fat. To maintain immune function, athletes should eat a well-balanced diet sufficient to meet their energy requirements. An athlete exercising in a carbohydrate-depleted state experiences larger increases in circulating stress hormones and a greater perturbation of several immune function indices. Conversely, consuming 30-60 g carbohydrate x h(-1) during sustained intensive exercise attenuates rises in stress hormones such as cortisol and appears to limit the degree of exercise-induced immune depression. Convincing evidence that so-called 'immune-boosting' supplements, including high doses of antioxidant vitamins, glutamine, zinc, probiotics and Echinacea, prevent exercise-induced immune impairment is currently lacking.

Exercise, nutrition and immune function

Irisin is produced by a proteolytic cleavage of fibronectin type III domain-containing protein 5 (FNDC5) and has emerged as a potential mediator of exercise-induced energy metabolism. The purpose of this study was to review the results of studies that investigated irisin responses to acute and chronic exercise and provide an update. A comprehensive search in the databases of MEDLINE was performed (74 exercise studies). The focus of the analysis was on data concerning FNDC5 mRNA expression in skeletal muscle and circulating irisin concentration relatively to exercise mode, intensity, frequency and duration and the characteristics of the sample used. Circulating irisin levels may either not relate to FNDC5 transcription or expression of the later precedes irisin rise in the blood. Acute speed/strength and endurance exercise protocols represent potent stimuli for irisin release if they are characterized by adequate intensity and/or duration. There are no reports regarding irisin responses to field sport activities. Although animal studies suggest that irisin may also respond to systematic exercise training, the majority of human studies has produced contradictory results. Certain methodological issues need to be considered here such as the analytical assays used to measure irisin concentration in the circulation. Results may also be affected by subjects' age, conditioning status and exercise intensity. The role of irisin as a moderator of energy metabolism during exercise remains to be seen.

Is irisin the new player in exercise-induced adaptations or not? A 2017 update.

Description of acute and chronic load, training monotony and strain over a season and its relationships with well-being status: A study in elite under-16 soccer players.

Irisin is a recently discovered myokine that plays an important role in fat metabolism through the browning of white adipose tissue. This myokine is usually secreted after exercise by improving energy balance and has shown great potential as a possible treatment for some metabolic diseases such as obesity, insulin resistance, and inflammation. Obesity has been linked to a higher incidence of some cancers. Furthermore, some studies have shown irisin to have direct positive effects on different types of cancers. Although it is hard to relay conclusions from in vitro to in vivo studies, the majority of the available data favor irisin as a potential substance for cancer regression through reducing proinflammatory markers linked to obesity. However, some controversies remain on the exact benefits of irisin on cancer with some studies showing no or even a negative effect of irisin on cancer. This review summarizes these 2 differing viewpoints and synthesizes them to form a clearer picture of exercise-induced irisin’s effects on cancer.

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Exercise-Induced Irisin, the Fat Browning Myokine, as a Potential Anticancer Agent

Regular aerobic exercise correlates with reduced anxiety and incresed levels of irisin in brain and white adipose tissue.

Monitoring collegiate soccer players during a congested match schedule: Heart rate variability versus subjective wellness measures

Background: Irisin is a new myokine secreted from the skeletal muscle and appears to affect the metabolism of adipose tissue. Objectives: The mechanisms of cellular and molecular identification by which exercise training exerts its benefits remain unclear and are under investigation. Methods: We examined the effect of 8-week resistance exercise on plasma irisin levels and expression profiles of muscle FNDC5 and subcutaneous adipose tissue UCP1 in male rats. Sixteen adult male rats were divided into two groups, control (n = 8) and exercise training (n = 8) groups. The training group received exercise for 3 days/week on a specific ladder (120 cm height) with a carrying load of 50% of body weight, which was attached to their tails. Results: The weight of the load was gradually increased during the training sessions, ultimately reaching 200% of the body weight of rats in the final week. There were three sets of five repetitions with a 3-min rest between each set of exercise sessions and 1 minute between repetitions. Plasma irisin levels and relative mRNA expression of the genes UCP1 and FNDC5 were assessed. The results demonstrated a significant increase in the irisin levels after 8 weeks of resistance exercise (P < 0.001, t = 4.48). The relative expression of FNDC5 (P < 0.001, t = 6.18) and UCP1 genes (P < 0.001, t = 13.91) was also significantly increased. Conclusions: Therefore, we can conclude from this study that resistance exercise may improve body composition possibly through increased thermogenesis in white adipose tissue through the secretion of irisin.

Can Resistance Exercise Alter Irisin Levels and Expression Profiles of FNDC5 and UCP1 in Rats

Simple Summary Overweight and obese, like other forms of malnutrition, have been shown to affect immune function through changing immunoglobin or cardio-respiratory fitness levels and cell-mediated immune responses. Although calorie restriction and exercise are the most common therapies for obesity or overweight, it is unclear what kind of supplementation these people should take or how much exercise they should perform. Hence, in this study, we examined the effect of 8 weeks of high-intensity interval training (HIIT) with spirulina supplementation on the humoral immunity, cardio-respiratory fitness, and body composition of overweight and obese women. The results demonstrated that spirulina supplementation with HIIT not only decreased fat free mass but also boosted immunoglobin-A, which plays an important role in the immune system. Abstract Our study examined the effect of 8 weeks of high-intensity interval training (HIIT) and spirulina supplementation on the humoral immunity, cardio-respiratory fitness, and body composition of overweight and obese women. Thirty sedentary women (height: 161.7 ± 2.8 cm, body mass: 75.8 ± 8.4 kg, body mass index [BMI]: 28.8 ± 2.5 kg/m2, age: 25.1 ± 6.7 years) were divided into three groups: placebo with HIIT group, spirulina group (SG), or combined group (CG). Exercise groups performed HIIT for 8 weeks, with three sessions per week and four to seven repetitions in each session of 30 s running and 30 s walking; the intensity was established at 90% of the maximum heart rate. Supplementation groups received 6 g of spirulina powder per day. Fasting blood samples were collected before and after 8 weeks to determine the concentrations of immunoglobulins (IgA and IgG). There was a significant group-by-time interaction for fat free mass (FFM; p = 0.001, f = 8.52, ηp2 = 0.39) and IgA (p = 0.036, f = 3.86, ηp2 = 0.22). The post hoc analysis revealed that CG reduced FFM significantly (p = 0.012, g = −0.55) after training. CG and SG showed significantly greater IgA concentrations after 8 weeks (p = 0.02, g = 0.70 and p = 0.001, g = 0.34, respectively). We conclude that spirulina supplementation with HIIT affects the body composition (lower FFM) but also boosts IgA, which plays an important role in the immune system.

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Effects of 8 Weeks of High-Intensity Interval Training and Spirulina Supplementation on Immunoglobin Levels, Cardio-Respiratory Fitness, and Body Composition of Overweight and Obese Women

Background: Betatrophin is a β-cell proliferation marker produced as a result of irisin expression. It is regarded as a therapeutic indicator of diabetes due to elevated insulin secretion. Objectives: The purpose of this study was to compare the effects of 2 different intensities of combined training on the levels of irisin, betatrophin, and insulin in women with type 2 diabetes. Methods: In this study, 26 female patients with type 2 diabetes were divided into 3 groups of combined high-intensity training, combined moderate-intensity training, and control. The training groups participated in combined training at high or moderate intensities for 8 weeks. The variance analysis test and the Duncan post-hoc test were applied to analyze the data (P > 0.05). Results: Combined training at 2 intensities of moderate and vigorous led to a rise in the levels of irisin, betatrophin, and insulin. Exercise intensity was a determining factor for these elevated levels insofar as combined high-intensity training resulted in higher levels of these hormones than combined moderate-intensity training. Conclusions: It appears that participating in relatively high-intensity training programs may be beneficial for diabetic patients inasmuch as they increase the levels of irisin, betatrophin, and then, insulin.

Comparison of the Effects of Two Different Intensities of Combined Training on Irisin, Betatrophin, and Insulin Levels in Women with Type 2 Diabetes

Aims: The aim of this study was to investigate the prediction of injuries in Iranian soldiers with the Functional Movement Screening. Methods: All the subjects were evaluated before the beginning of the trainings. The FMS tests including the deep squat, hurdle step, in-line lunge, shoulder mobility, straight leg raise, trunk stability push-up and rotary stability were used for the subjects’ evaluation. They were monitored for musculoskeletal injuries resulting through a 7-month basic combat training period. Results: At least one musculoskeletal injury had been suffered by 42% of the cadets during the observation period. Logistic regression modeling indicated that the subjects who had a lower FMS score demonstrated higher injury risks (p=0.001). Also, considering the ROC curve and the Yourdon's index, the score of 14 was considered as a cut-off point. Therefore cadets whom FMS scores were lower than 14, were considered 5.6 time higher than the other soldiers exposed to lower extremities injury ROC curve with a cut-off point equal to 14 which shows sensitivity of 0.83 and a specificity of 0.93. Conclusion: We can conclude from this study that functional movement screening can predict lower extremity injuries during medical in-processing.

Jalil Reisi

Papers

Monitoring collegiate soccer players during a congested match schedule: Heart rate variability versus subjective wellness measures

Can Resistance Exercise Alter Irisin Levels and Expression Profiles of FNDC5 and UCP1 in Rats

Effects of 8 Weeks of High-Intensity Interval Training and Spirulina Supplementation on Immunoglobin Levels, Cardio-Respiratory Fitness, and Body Composition of Overweight and Obese Women

Comparison of the Effects of Two Different Intensities of Combined Training on Irisin, Betatrophin, and Insulin Levels in Women with Type 2 Diabetes

Can Functional Movement Screening Predict Injuries in Iranian Soldiers