• endurance_training

The role of endurance training in disease prevention

Ahmed Khaled Abdelrahman Abbas, Isaac Grech, Guo Jiaen

Contents

Abstract:.......................................................................................................................... 1

Investigating changes in pro- and anti-inflammatory cytokine profiles in Arabian horses undergoing and endurance training program...................................................................... 1

Role of Cytokines:.......................................................................................................... 1

The resting hemogram:..................................................................................................... 4

Endurance trained male rats vs untrained one’s comparison:.............................................. 5

1.1. Motor system......................................................................................................... 5

1.2. Metabolic system.................................................................................................... 5

1.3. Cardiovascular system............................................................................................. 6

1.4. Nervous system...................................................................................................... 6

1.5. Urinary system....................................................................................................... 6

1.6 Cancer..................................................................................................................... 6

Endurance training effects to heart in Human:.................................................................... 7

Endurance training effects to heart in Animals:................................................................... 7

Conclusion:....................................................................................................................... 8

References:...................................................................................................................... 8

Abstract:

Endurance training is a routine program in most of the athletes training. Daily exercises such as running and swimming have been proved that can help in disease prevention and treatment. In this article we compare and summarize different studies and articles which are about the effects of endurance training either on human or in animal in different aspects. Endurance training does have the benefit effects on some aspects such as anti-inflammation, but exceeding endurance training may do harm to for example the heart, especially in animals.

Investigating changes in pro- and anti-inflammatory cytokine profiles in Arabian horses undergoing and endurance training program.

Witkowska-Piłaszewicz. O et al, (2019) implemented a stuy were, 9 young Arabian horses went through a 20-week training program, particularly targeting endurance training. The horses under study were young thus also inexperienced. Throughout these 20 weeks all the horses were constantly examined. These examinations included blood sampling before and after each training session. Such sampling was repeated for 5 times a month in order to observe the difference in hematological results before and after training sessions as the training program progressed. Cytokine patterns were also examined. These include: IL-1β, IL-6, TNF-α, IL-2, IL-4, IL-10, IL-17. These cytokines profiles were examined by using PCR tests and ELISA Tests.

Role of Cytokines:

Interleukins are mainly produced by macrophages, monocytes, dendritic cells, natural killer cells, B-lymphocytes and neutrophils after stimulation. Interleukin-1β is one of the cytokines responsible for the immune response of pathogenesis of a lung injury or a respiratory disease. Interleukin-6 causes an inflammatory response.

TNF-α is a protein released by macrophages. This protein function as a signal to other cells in order to evoke an immune response. Similarly, this particular protein induces the gene expression of various inflammatory cytokines and chemokines. Additionally, this TNF-α-mediated signaling initiates and accelerates atherogenesis, thrombosis, vascular remodeling, vascular inflammation, endothelium apoptosis, vascular oxidative stress and impaired NO bioavailability, which contribute to the blunted vascular function. (Zhang. H et al, 2009)

Interleukin-2 is responsible for stimulating white blood cells that cancerous cells thus by doing so it stops the rapid spreading and reproduction of cancer cells.

Interleukin-4 is important for the stimulation of B-cells which are vital for a competent immune system. Thanks to B-cells an organism can produce antibodies which identify an antigen and lead to an immune response. This interleukin is also vital for T-cell proliferation which are important for killing infected cells.

Interleukin-10 is responsible for limiting inflammatory responses whilst interleukin-17 has role in the induction of other interleukins as confirmed by (Mensikova et al, 2013).

One may ask why horses were used in this study. When compared to humans, horses are better test subjects as they are not involved in other daily activities which can lead to a disruption of the training program thus eventually influencing the results. Despite this, horses also have a very natural athletic capability and can withstand training for a long period of time. highlight the capability of the horse as an athlete. Nonetheless Arabian horses are one of the best breeds when it comes to athletic competence.

The daily exercise load of each horse varied depending on the condition of the horse. Within a month each horse covered approximately 28km so altogether the horses covered 250km per month. It should also be mentioned that every 14-20 days the horses performed sessions with a high exercise load and training intensity. A vet used to examine each horse before and after training. A clinical examination would include examination of heart rate, mucous membranes, dehydration, gut sounds, muscle condition.

Table of Hematological Results: (Table 1)

WBC: White blood cell count

RBC: Red blood cell count

HGB: Hemoglobin concentration

PLT: Platelet count

Table of Concentration of Cytokines in blood samples collected before and after each training session: (Table 2)

Discussion of Results of Table 1 and 2:

All the above results show the average data of all the nine Arabian horses under test. When it comes to the hematological results (Table 1) there was an overall increase in all the parameters. Also note that there was a decrease in the cytokine levels after training (Table 2). The decrease of cytokines would show a reduction in inflammatory capacity. One could also highlight the possibility that due to the decrease in cytokine level and inflammatory capacity, there would be an increase in the induction of anti-inflammation.

The level of IL-6 at the beginning of the training season was higher than at the end. The high level of IL-6 may have prevented the production of type 1 pro-inflammatory cytokines such as IL-β and TNFα, this would aid the horses in reaching an anti-inflammatory state.

As the training progressed the immune system evidently continued to adapt along with a progressive increase in workload during training. This adaptation of the immune system of each horse shows, that eventually there would be no inflammation developing in the muscles with an increase in workload.

To conclude the results, indicate that endurance training leads to the gradual development of a reduced inflammatory capacity. This reduction can be confirmed by a decrease in pro-inflammatory cytokine concentrations and eventually reaching anti-inflammatory state.

It is clear that the hematological values are affected with endurance training.

The resting hemogram

Poor reproducibility of Red Blood Cells - RBC in the resting racehorse has been reported, which may be due to its large capacity of sequestering blood cells in the spleen Garcia and Beech, (1986). The RBC ranged between 1.8-2.8% of the bodyweight at rest and up to 8% during exercise, which is workload-dependent and is mediated by sympathetically splenic mobilization (Evans et al., 1990), i.e., up to a 50% increase in the population of equine RBC in circulation during exercise (Persson et al., 1973). Therefore, Hematocrit - HCT values in resting horses may not be a good indicator representing the whole blood profile. A negative correlation between the HCT and erythrocyte sedimentation rate (ESR) was observed in the previous study (Ju et al., 1993). Evans et al., (1990) provided illustrations of athletic horses’ responding to an endurance training program under the environment of Taiwan.

Persson et al. (1973) reported that prolonged exercise-induced leukocytosis, which was caused by the release of cortisol. The leukocyte counts usually returned to normal levels within 24 h after exercise. The WBC counts responded clearly in a time-dependent manner after exercise as well as other parameters including RBC, HCT, and Hb values. They largely followed a pattern of increase-with-time of exercise and then returned to their initial values at the end of the recovery stage or 45 min after exercise. It is generally agreed that about one-third up to 50% of the blood cells are stored in the spleen at rest (Jones, 1989). Exercise causes the production of epinephrine, which in turn expels the spleen to eject the stored RBC into peripheral circulations (Garcia and Beech, 1986). However, endurance horses working at slow speeds for long periods experienced a different hematological response. Due to the incomplete splenic mobilization, the RBC, WBC, or HCT would not increase as much as that in intensive exercise such as competitive racing (Evans et al., 1990). The morphology and membrane characteristics of RBC may be altered by exercise. RBC osmotic fragility (Boucher, 1989) and the proportion of the crenated RBC, an abnormal RBC morphology known as schistocytes, increased. Although environmental factors such as nutrition, track surfaces, shoes, and jockey are all critical in successful racing, adequate training is one of the most important variables determining athletic performance after genetics.

On the other hand, apart from the impact of endurance on horses, one can also compare endurance trained male rats vs untrained ones. Exercise is considered an important intervention for the treatment and prevention of several diseases; There are a lot of differences in the effects of exercise talking about six systems. Experiences in rats were made to model these.

Endurance trained male rats vs untrained one’s comparison

1.1. Motor system

The main functions of the motor system are movement, support, and protection. Morais et al (2017) has recorded that exercise methods can prevent osteopenia by improving bone mineral density reducing bone loss and maintaining bone mass. Exercise protocols showed positive effects on muscle regeneration and recovery from the slow/oxidative phenotype. In resistance training, rats improved skeletal muscle regeneration through increased myogenic differentiation (MyoD) and myogenic factor 5 (Myf5) mRNA levels. Resistance training plays a potential role in preventing aging-related injuries such as tendon aging. Li et al (2017) stated that Physical activity, specifically treadmill and vibration platform training, could be a treatment for cartilage disease such as Osteoarthritis (OA) which is the most common disease affecting the joints. It is characterized by progressive degeneration of cartilage. The exercise protocols showed positive effects on muscle mass, fiber-type redistribution, and skeletal muscle function. Therefore, has a positive effect on preventing skeletal muscle atrophy (Krug et al. 2016).

1.2. Metabolic system

Catabolism and anabolism are the 2 processes essential for maintaining the normal condition of the human body and are the main components of metabolism. Metabolic disorders can lead to several diseases. Exercise protocols all showed positive effects on treating or preventing Obesity by reducing weight, increasing insulin sensitivity, and improving energy metabolism in obesity- related signaling pathways Perry et al. (2016) showed that Exercise protocols recorded positive effects in preventing Diabetes in male rats at different ages and in improving glucose metabolism and insulin resistance in rats with diabetes. Exercise protocols positive effects on Metabolic syndrome symptoms, such as triacylglycerol levels, lipid uptake, fatty acid oxidation, and other important factors (Janssens et al. 2015)

1.3. Cardiovascular system

Physical exercise is recommended as part of the rehabilitation for patients with heart diseases because it reduces the risk of heart disease, prevents myocardial damage, and improves heart function. Exercise can reverse pathologic Cardiac hypertrophy into physiologic cardiac hypertrophy which produces a large number of new blood vessels in the epicardium as well as ventricular hypertrophy. The blood vessels are fully capable of coping with the thickening of the ventricular myocardium. Yang et al (2010) has mentioned that the effectiveness of exercise has been reported in many animal experiments using cerebral ischemia models, for preventing Stroke which is the leading cause of disability and the 3rd highest cause of death in the world. Cornelissen and Smart (2013) revealed that exercise training is beneficial in the treatment of Hypertension. Exercise at long-term duration and moderate intensity may help protect the organism against Myocardial injury, which could be effective in reducing cardiac mitochondrial apoptotic, myocardial inflammation, edema, and fibrosis, and increased collagen content. Exercise can also prevent Atherosclerosis (AS) which is a pathologic condition that is the basis of several important adverse vascular events, such as angina, myocardial infarction, and spasm (Ishii et al. 2016)

1.4. Nervous system

The nervous system, including the central nervous system and the peripheral nervous system, plays a leading role in regulating physiological and functional activities in the human body. Exercise as a treatment for Parkinson's disease (PD) has been more and more widely used (Ahlskog JE. 2011). Currently, the treatment of Alzheimer’s disease (AD) is based mainly on drugs and diet. Ryan and Kelly (2016) reported that exercise therapy is also being investigated as another option for treating AD. Research in the field of sport in the treatment of Epilepsy has shown positive results. Further investigation is necessary to establish the relationship between sports activities and epileptic cognition.

1.5. Urinary system

Diseases can occur in the organs of the urinary system (kidney, ureter, bladder, and urethra) and spread to the whole system. Exercise is an increasingly effective method in the treatment of patients with chronic kidney disease (CKD), resulting in improved physical health, cardiovascular health, and quality of life (Clarke et al. 2015).

1.6 Cancer

Refers to a malignant tumor originating from epithelial tissue and is the most common type of malignant tumor. Breast cancer is generally treated with surgery and chemotherapy. Exercise can also be used as a therapeutic method for treating and preventing breast cancer. The exact causes of colon cancer are not clear. Colon cancer generally requires surgery and medication. Exercise therapy is also used as a treatment for patients with colon cancer (Brown et al. 2012).

People believe that exercise have a positive effect on cardiac disease treatments also on prevention. There are numbers of experiments and publications in human medicine, but limited documents in Veterinary medicine. Beside functional change, physical exercise or endurance training also have the effects on morphological change in heart.

Endurance training effects to heart in Human

A review research studied 1286 human patients who have suffered from coronary artery disease and have experienced heart attack previously, found that doing home exercise 3-7 times per week helped to decrease the systolic blood pressure, decrease the LDL but increase the HDL, which means the coronary artery disease risk factors have been improved.(Yu-Chi Chen et al, 2017) Meanwhile, exercise training can improve the muscle function including heart muscle, therefore it brings beneficial to heart failure human patients.(Renée Ventura-Clapier et al, 2007) Resistance training is also recommended to be a fitness program in human in preventing cardiac disease, as it can raise the ability of oxygen pumping by the heart. (Naga Meka et al, 2008)

Endurance training effects to heart in Animals

In veterinary medicine, there are several studies have different findings regarding to the effects of endurance training on the hearts. A study used rabbits and dogs as experiment models, by treadmill exercise for 16 weeks. After performing echocardiography and electrocardiogram, they found appearance of enlargement of the left ventrical with bradycardia, accompanied by heart rate increasing. (Alexandra Polyák et al, 2018) Another study looked into the cardiac morphology change in Alaskan sled dogs with endurance training. 77 Alaskan sled dogs go through 5 months of training (20km/day), resulted in a decreasing heart rate and the thickness of heart muscle. However, there is a overall increasing of murmur intensity, and the cardiac output, ejection fraction, stroke volume had limited change with training. (R. L. Stepien et al, 1998)

There are adequate evidence in human medicine that endurance training has positive effects on heart disease prevention, according to this we believe this effect also act on animals but need more further studies. Meanwhile, high intensity training will bring functional damage to the heart.

Conclusion

Endurance training has different effects on various aspects. It leads to the gradual development of a reduced inflammatory capacity. It has a positive effect on preventing skeletal muscle atrophy, also on metabolic system such as triacylglycerol levels, lipid uptake, fatty acid oxidation. The nervous system and urinary system also benefit from the training. There is adequate evidence in human medicine that endurance training has positive effects on heart disease prevention, according to this we believe this effect also act on animals but need more further studies. Meanwhile, high intensity training will bring functional damage to the heart.

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