Acute effects of whole-body vibration on interlukin-10 and cortisol responses in the athlete and non athlete girls

ABSTRACT

INTRODUCTION: The aim of this study was to evaluate the acute responses of blood hormone concentrations following whole – body vibration (WBV) treatment.

METOTHOLOGY: 10 femail athletic [ means (SD) age 23.4 (1.4) years ] and 10 femail non-athletic subjects [ 22 (2.3) years ] were exposed to vertical sinusoidal sets WBV,10 times for 60 s, with 60s rest between the vibration sets (a rest period lasting 6min was allowed after 5 vibration sets). Blood sample were collected before, immediately and 2h after the WBV, and plasma concentrations of Cortisol (C) and IL-10 were measured.
RESULTS: The results showed a significant decrease in the plasma concentration of cortisol and IL-10.

DISCUTION: These results suggest that WBV treatment leads to acute responses of hormonal profile. It is therefore liklt that the effect of WBV treatment elicited a biological adaptation that in connected to a hormone effect. In conclusion, it is suggested that WBV influences in hormonal responses.
Moreover, since the hormonal responses, characterized by a decrease in C and IL-10, it is speculated that the two phenomena might have common underlying mechanisms.

INTRODUCTION

Recently, sport immunology has been noticed by many researchers of sport science, physiology, immunology and behavior sciences. It has been found that there is significant relationship between neuro-hormonal and immune systems. Sport effectively alters hormone level and neural system functions. Considering the extensive studies in this context, it has been found that the exercise directly and indirectly affects the immune system function and alters the immune system process. Data indicate that the immune response is associated with the intensity, duration, individual readiness, sampling method and time, measuring methods, age and the health or illness of the person (1, 2, 3). Exercise influences on the acquired and innate immunity. Cytokines (IL-10, IL-1 and IL-6) are the non cellular immune elements.

Four points are understood from the immunologic findings, as follow:

1- Exercise changes some immune functional aspects positively or negatively, though some parameters are not under the influence of exercise. It is unclear whether some of the exercise induced changes are useful or not (example, elevation of cytokines, turning to the initial condition after exercise, and reverse regulation of neutrophils preparing)

2- Exercise changes the immune response in the diving cells (such as surviving from infection, and cancer onset) and also certain immune factors (such as lymphocyte proliferation)

3- Generally there is a response-rate relationship between exercise and particular immune responses. There is significant interaction between the exercise duration and exercise intensity, and to a certain level of readiness, in determining the particular immune parameters in the exercise

4- There are contra indications about the immune response to exercise, the reason could not be explained completely yet (like some reports on increase of cytokines) while in some athletes such increase has not been noticed (4).
There are evidences indicating that at the time of exercise, the stress hormones act as mediator in changing the while cell corpuscles number and redistribution of their sub cellular fragment, but such relationship seems to be complex. It has been cleared that hormones such as epinephrine and cortisol affect the redistribution of the white blood corpuscles between blood circulation and spleen, liver and bone marrow. Physical exercises lead to the stimulation of the acquired and innate immunity, the cellular and non cellular immunity and their sub classes (5).

Exercise causes the starts of cascade like activity of main part of the leukocytes known as cytokines and immune cells (6). Cytokines response to exercise is complex and related to the training variable, previous training, the sample type (tissue, blood and urine) and measuring method (5). The mechanism of cytokines secretion during exercise is unclear yet, and seems to release after long exercise or the exercise leading to tissue damage. Role of immune system interaction with the nervous system, metabolic and endocrine systems is clear. The time and type of training, the involved tissues, the type of involved metabolic process (aerobic or anaerobic) or combination of them lead to excess function or suppression of the system during training or at the return period to the initial condition (6, 7, 8). The effect of various exercises on different parts of immune system has not had the same response (6). Different studies demonstrate that people with regular medium intensity training, are more resistant to infections. The medium intensity exercise improves immune system and possibly the physiologic function of the immune system.

The light, aerobic and regular training leads to the positive function of leucocyte receptors and their sub classes such as the pre inflammatory and anti inflammatory cytokines (IL-10, IL-1) and the immune cells and affect the innate and acquired immunity (9, 10). Intensive training enhances the pressure on the muscle, increases the inflammation and other severe changes which leads to immune disorder (11). Heavy exercise may weaken the immune system and lasts for several hours during the recovery period, ultimately deficiency of cytokines (IL-10 and IL-6) production and function (6). One of the mechanisms involved in changes of immune function during exercise, is related the changes of stress hormone, like cortisol. Cortisol suppresses immunity. During and after physical exercise, serum and salivary cortisol level increases.

Findings indicate that heavy exercise increases serum and salivary cortisol and remains long term after exercise. Researchers emphasize on the significance of cortisol as regulatory hormone of the immune response and immune system changes after exercise. No research on the immune system responses to the whole-body vibration (WBV) and its relationship with the immune responses has been done yet. Study on the effect of WBV related to the IL-6 indices, cortisol and creatinine kinase in the men elite football players in Iran revealed that the IL-6 and serum cortisol level after vibration declines significantly and creatin kinase do not increase (12). Studies in 2007 and 2008 on the effect of the WBV on different hormone levels showed insignificant changes of cortisol and testestrone levels after vibration compared to the before vibration (13, 14). Use of vibration training started since 40 years ago. In the ancient Greek, vibration has been used for the immediate treatment of injuries (15, 16, 17).

When for the first time the Russians used the vibration training to maintain the zero effect on the astronaut skeletal system, they started using the vibration in different sports (16). Bosco was the first who noticed the positive and exciting effects of vibration training. They showed that vibration is a mechanical stimulus described by oscillatory motion. Despite the recent studies on vibration training, the exact mechanism of vibration behind the muscular function leading to the improvement of exercise performance is not clearly understood yet (17). WBV training in the health centers is recognized as a training method together with the other training methods. Different risk factors of vibration training have been studied extensively at particular frequencies and amptitude on man (18). On the other hand, recently has been suggested that, mechanical stimulation with the low frequency and amptitude, is effective way in preparing the skeletal structures (18).Effects of WBV training on healthy men hormonal system has been studied by Diloreto et al. (2004). They tested 10 healthy men at 30 Hz frequency in 25 min on the vibration plate.

It showed a significant decline of blood glucose after vibration training, but norepinephrine increased. Insignificant difference was observed on insulin, glucagons, cortisol, epinephrine, and testestrone levels (19). Bosco et al. (2000) studied the effect of WBV to hormonal response in 14 male subjects mean age 25±4.6 years, exposed to vertical sinusoidal WBV, 10 times for 60 seconds, with 60 seconds rest between vibration sets, a rest period lasting 6 min was allowed after 5 and 6 vibration sets. Findings indicated increase of testestrone and growth hormones level, but serum cortisol level significantly decreased (20). No research has been done about the effect of vibration on IL-10 yet, but for more information, number of the studies related to exercise and IL-10 are discussed.

Markovitch et al. (2008) studied the acute effect of moderate intensity training on 12 non active young men age of 54±4 years, divided in two moderate intensity training and rest groups. Training was performed in 30 min with 50% maximal oxygen up take. In 7 days, insignificant changes in neutrophils, lymphocyte, monocyte and serum IL-6 and IL-10 level was observed (21). Nunes et al. (2008) studied on the increase of IL-10 level, left ventricle and blood pressure and per oxidation of muscle fat by training. The subjects under study, swam for 60 min/day, and 5 days/week for 8 weeks. It was found that in the non trained the IL-10 level was lower than the trained subjects (22). Yamade (2007) studied the effect of warm adaptation on the IL-10 level in 10 male and 20 female in 10 days lasting 100 minutes with 56% of maximal oxygen uptake at 42.5 ºC. Blood sample were collected on the 1st, 6th and 10th days, before and after training. It was found that IL-10 level had insignificant change after training and after 10 days (23). Oberbach et al. (2006) reported the effect of 4 weeks physical exercise on the plasma level inflammatory signs in the patients with unusual glucose tolerance. Increase of insulin sensitivity after training was noticed, but insignificant change of IL-10 and IL-6 concentration (24).

Kohut (2004) found that IgM and IL-10 increase in the athletes by regular training (25). Nieman et al. (2001) reported increase of IL-10, IL-8 and IL-1ra level after a maratun race, in the carbohydrate group, but IL-6 did not change significantly in the carbohydrate and placebo groups. The participants were 98 runners placed in two carbohydrate and placebo groups. Blood sample was collected 90 min after the match. Blood glucose was higher in the carbohydrate group and cortisol level lower than the placebo group (26). Studies revealed that WBV results in enhancement of body strength, which depends on to the characteristics of the vibration training amptitude, frequency and method of applied and the training protocols (intensity, volume, and type of training). It has been shown that, a training protocol with certain frequency, amptitude and condition significantly increases training performances. While when the same protocol in the condition but in the low amptitude was conducted elsewhere, insignificant different result was observed.

Due to existing contraindication on a particular training protocol, presenting and use of this method should be done with care, that demands further studies. Suggestion of a comprehensive and effective program is felt. The reason of finding similar or contradicting data in studies is attributed to the difference of subjects’ gender, age, the time test being done, amptitude, time and frequency of the vibrating machine, type of vibration training and the intension of the subjects under study. In most of the studies no comprehensive and simultaneous study have been done on the performing indices like, speed, agility, balance and figure of body and most have been done on the athlete or non athlete male and female, but less has been paid to compare the effects in the two groups. No study on the context of the effect of WBV on the immune system has been alone yet. No attention has been paid to the issue as to, whether WBV training causes any muscular and inflammatory defects. Proper selection of vibration training protocol helps the instructors, the athletes and non athletes to keep away their immune system from the injury and this issue could be very important to the sport society, because the athletes with heavy exercise suppress their immune system and acquire infections at the time of match and during training performance. Due to difference of immune response to training between males and females and lack of relevant data, still the question is that, as to whether one session of WBV training influences the serum IL-10 and cortisol level in the athlete and non athlete girls.

METHODOLOGY

Since control of all effective factors on variables of the research was not possible, hence it was done in a semi experimental method. The participants were the athletes and non-athletes subjects. The non athletes were all female students aged 20-25 years in their first term of the academic year 2009-2010, at the faculty of physical education Varamin-Pishva Branch Islamic Azad University. They had no exercise experience till the day of study. The athlete participants were the girls aged 20-25 years from footsall teams of Tehran province, all with playing experience of 4±1 years. From athlete group 10 persons were selected randomly with mean age of 23.4±1.4 years, height 166±4.43 cm and weight 61±3.2 Kg. From non athlete group 10 persons with age of 22±2.3 years, height 168±4.15 cm and weight of 63±3.26 Kg were selected. None of the participants on the day of sampling were in menstrual cycle. No subject had history of chronic pains, allergy and immunologic complication, and did not use any drug regularly.

 RESEARCH METHODOLOGY

One week prior to the beginning of the study the subjects performed the vibration test for 1 min, as an introductory. They were told not to have any heavy exercise 24 h before the beginning of the test. The study was done in one day as follow:
10 repeats of 1 min, frequency of 40 Hz and amptitude of 4 ml at a half with knee reflexion of 100º exposed to vertical sinusoidal MBV. A rest period lasting 1 min rest was allowed between each repetition and between the repeats 5th and 6th, 6 min rest was allowed (Bosco 2000). Blood samples were collected from the left hand brachial vein before, immediately after, and 2 h after vibration. During blood drawing, the subjects sat down on the chair, the arm fasten with turniket by the lab. expert, 10 ml blood was drawn, and collected in test tube. They warmed up before and after the first blood collection by reflecting and extending movement, and only drank water since 3 hours before beginning of training till after the 3rd blood collection. The samples were kept frozen at -20 ºC until assayed. Since the tests were performed in a day, hence the samples were kept in the laboratory for a short period.

DATA COLLECTION TOOL

The used tool were as follow: NEMES whole-body vibration machine, Jet-Vibe EST 900 N model, Germany; Hunhart chronometer, Germany, for measuring and recording of the obtained data with accuracy of 0.01 second, 5 ml syringe for blood drawing; The laboratory cooler, with 5 hours cooling efficiency; Kid of serum cortisol and interlukin-10.

MEASURING METHODS

For measuring of serum cortisol and IL-10, the ELISA kits from IBL company, Germany, with the sensitivity of 0.05 ng/ml and 2.3 pg/ml for interlukin 10 were used.

DATA ANALYSIS

For description of the obtained data the descriptive statistic test, and for data analysis, the inferential statistic methods such as variance of analysis (ANOVA) with repeated measurements and following test of LSD, and Pearson correlation test were used SPSS software was used for statistical analysis.

FINDINGS

The results of analysis of variance with repeated measurements in studying the effect of time on serum IL-10 level in athletes and non athlete girls show that, there is significant difference among the three time periods. LSD following test data show that there is insignificant difference between the serum IL-10 level changes prior to and immediately after training, but there is significant difference between immediately after training and 2 h after training, and between prior to training and immediately after training (figure-1). In the non athletes, insignificant difference of serum IL-10 level changes was seen between prior to training and immediately after training and between immediately after training and 2 h after training, but significant difference was observed between prior to training and 2 h after training (fig-2).

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One session vibration training has significant effect on the serum cortisol concentration in the athletes and non-athletes girls (P≤0.05). Serum cortisol concentration in the athlete girls immediately after training and after training showed significant difference compared to the before training, but insignificant 2 h after training compared to immediately after training (fig-3). Also serum cortisol concentration in the non athlete girls immediately after training showed significant decline compared to the before training, and had significant difference 2 h after training compared to immediately after training. Insignificant difference was noticed between before training and 2 h after training (fig-4).

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DISCUSSION

Findings showed that serum cortisol level in the athlete and non athlete girls immediately after training compared to before training had significant decline, but insignificant difference in the athlete girls immediately after and 2 h after training. In the non-athlete girls, insignificant difference was found between the levels before and 2 h after training. One of the mechanisms involved in the immune performance changes and energy metabolism in sport is related to the cortisol changes. Heavy exercise in short time like, repeated 60 second jumpings (27), anaerobic exercises (9, 28), weight lifting (29, 30) lead to hormones responses. There is strong relationship between blood hormone level and short time activities (27, 29).

Bosco et al. (2000) studied the effect of WBV on the hormonal responses in the athlete females. They found increase of testestrone and growth hormone and decrease of blood cortisol (20). Cortisol is one of the main hormones regulating the sugars and lipids metabolism, it causes lipid released from the lipid tissues and liver glycogenolysis. It provides required energy for long term activities by affecting the muscles and lipid tissue (31). There are studies about the increase of cortisol in different sports such as football, weight lifting, and strength sports (32). Stress is one of the factors directly influences the stimulation of cortisol secretion. If sport is considered as stressor, the plasma cortisol levels remain unchanged or increased. When cortisol increases, it causes two things: (1) Increase of liver glycogen and lipid tissue triglyceride for increasing the blood sugar. (2) Immune system suppression. Many researchers confirmed the function of cortisol as a hormone which regulates immune responses and causes changes of immune system after exercise (4). There are different mechanisms involved in increase of cortisol level following heavy exercise.

One of them is increase of hormone secretion though stimulation of hypothalamus, hypophysis-adrenal which increase ACTH secretion from hypophysis. As it is known, increase of ACTH secretion acts as a main inducer of cortisol secretion (32). It is found that the change in cortisol level depends on the intensity, duration and type of exercise, physical fitness and mental pressure (32, 33). Kis et al. (1995) showed that cortisol level is related to the age (34). The more decrease of blood sugar, the more increase of cortisol concentration. These findings agree with the data obtained by Zolanderland, Kopasalami and Marnili (35, 36, 37). Testestrone-cortisol ratio (Bosco 2000) is an anabolic to catabolic index.Increase of this ratio indicates increase of anabolic processes. Changes in secretion of anabolic-catabolic hormones, influences the cellular changes due to protein synthesis and muscle fibers functions.

If the catabolic hormones responses increase, possibly cause proteolysis. Kraemer et al. found that reduction of muscle fibers is related to the cortisol increase in the subjects under endurance exercise (28, 29). Permans et al. (2001) reported increases of cortisol secretion when vibration is done in lower intensity, which explains its role in providing energy and lipolysis. In the present study and of Viru et al. (2005) reduction of cortisol level was observed following vibration training, which is possibly related to the intensity of vibration used. It could be hypothesized that “high intensity vibrations, similar to strength exercises of moderate intensity causes hormonal response” (38). Since in the present study the serum cortisol level decreased, it could be concluded that insignificant stress due to vibration training has taken place (39). Increase of cortisol level is followed by increase of blood glucose and lipid.

Therefore it is concluded that vibration training does not require its energy be provided through liver glycogenolysis or from lipolysis of the lipid tissues and this training is somewhat similar to the strength training and induces hormonal responses. IL-10 decrease is also another reason of this function. Cortisol is an anti-inflammatory hormone and IL-10 is also an anti-inflammatory cytokine secreted after onset of inflammation. Therefore it could be stated that, it was due to lack of inflammation that cortisol did not secrete to act anti-inflammatory. On the other hand, during training the immediate endocrinal response is induced by the autonomic centers and the neuro-hormonal section of hypothalamus by central movement ways. Followed by the effects on the muscular receptors (25). Bosco (1998) believes that vibration does not have an absolute effect on the cerebrum cortex. Vibration does not use efferent ways originated from cerebrum cortex (40). Kachaer et al. (1987) stated that the increased demand for activity is associated with the increased activity of adrenal and adrenocortical systems.

Therefore decrease of cortisol level due to low stimulation of movement ways which is related to the type of vibration training, causes decrease of sympatho adrenal and adrenocortical systems stimulation. Also decrease of cortisol accumulation allows us to predict as inhibitory effect on the hormonal centers of hypothalamus (36). When the effect of strength exercise along with vibration is studied on cortisol response, insignificant difference between the strength exercise alone and strength exercise with vibration is observed (38), but the intensity of vibration training used by these researchers was not sufficient. May by using of higher intensity (like this study) with strength exercise has more potential effect. Also, it is possible to use this exercise with different sports training considering the similar effect of strength exercise in this vibration or by replacing vibration with strength training, and reduce the possibility or the injury of strength exercise particularly in the athletes who have history of injury.

The results of the present study showed the significant reduction of serum IL-10 level in the young girl athletes, immediately after and 2 h after training but its level in before training as compared with the after and 2 h after training had insignificant difference. Also in the non athletes there was significant difference between before training and 2 h after training, but insignificant difference was observed in the other times. Numerous studies have been done about the effect of vibration performance of different exercises and the muscular responses mechanism (27, 41, 42, 43, 44) and hormonal responses (20, 38, 45) which confirm the positive effect of vibration on exercise performances. No research on the effect of vibration on the immune system and its responses has been done yet. The physical stress of body affects the immune system function in different ways (46, 47, 48, 49). Vibration as a kind of physical activity can cause similar physiologic responses (3, 7, 50). Daryel defines vibration as a kind of exercise.

Despite, study on the immune system response particularly on IL-10 considering its anti-inflammatory role in response to different exercise seems necessary. In this regard, the present study pays to determining the IL-10 response to one session acute vibration exercise Cytokines can induce extensive immune changes (51). Mechanisms of cytokines in sports are not clear yet, and seems that they are released after long term exercise or during the exercises which cause muscular injuries (4). Recently Stizenberg et al. (2003) showed that the minor increase of plasma IL-6, stimulate the production of IL-10, IL-1ra and CRP (73). During exercise IL-6 increases these two cytokines and seems that, IL-6 released from muscle is the starter of this response. IL-6 and IL-4, stimulate monocytes and macrophages for production of IL-1ra which acts as inhibitor of IL-1 effects.Type 2 T-lymphocyte, monocytes and b-Lymphocytes are the main IL-10 producers which can inhibit cytokines produced by type-1 T-lymphotes.

On this bases, intensive exercise, reduces number of type 1 T-lymphocytes but, number of type-2 T-lymphocytes does not change. Cortisol and adrenalin suppress production of cytokine by type-1 T-lymphocytes. While IL-6 directly stimulates production of cytokine by type-2 T-lymphocyte. It worths to emphasize that shift (transit) towards type-2 T-lymphocytes is beneficial, because suppresses the efficiency of immune system in tissue damaging (52). To know whether the other cytokines act similar to IL-6, Jan et al. (2004) (53) and Nieman et al. (2004), (51) studied the expression of mRNA in some cytokines in response to longterm exercise. At the rest condition, mRNA of some cytokines like IL-1b. IL-6, IL-8, IL-5, TNFa, IL-12p35 and IFNa¢ could be detected in the skeletal muscle. In contrast, mRNA of the other cytokines such as IL-1a, IL-2, IL-10 and IL-12p40 were not detected. In both studies sport related increase of IL-10 mRNA expression was not observed. Since the IL-10 and IL-1ra are the anti-inflammatory cytokines, it is probable that sport related increase of IL-10 and IL-1ra concentration acts as a negative feed back mechanism for control of the rate and time effects of IL-1 and IL-6.

In this study, IL-6 was not measured and IL-10 level decreased after vibration exercise. Since IL-10 is an anti-inflammatory cytokine, and in case of inflammation is produced to decrease the IL-6 caused inflammation. Therefore it is concluded that vibration training in the present study did not cause injury and muscular inflammation, probably IL-6 level did not increase. Data on the performance of many cytokines related to exercise is little and further studies to understand the biological role of cytokines on exercise are necessary.

CONCLUSION

Findings of the present study indicated that one session vibration training at 40 Hz frequency causes decrease of IL-10 and cortisol significantly. The reason could be attributed to the nature of vibration, intensity, time or amptitude of vibration performance. Change in each of the above mentioned factor could have different effects on serum IL-10 and cortisol level, as indices of immune-hormonal system. Since there is controvery about presenting a protocol with certain frequency, amptitude and time of WBV, further relevant studies are suggested.

ACKNOWLEDGEMENT

Thanks to the authorities of the Enghlab Sport Complex for providing the vibration machine, special thanks devoed to the Noor Medical Diagnostic Laboratory for examination of the collected samples and to the research deputy of Varamin-Pishwa branch Islamic Azad University for the financial supports.

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