Fatigue

Contents: Definition, causes, Types, Chronic fatigue, Overtraining, Management

1. FATIGUE BY UMA DOBARIA

2. FATIGUE In general terms fatigue is “General sensation of tiredness and accompanying decrements in muscular performance” Underlying causes and site of fatigue can be described by : 1. The energy system (ATP- PCr , anaerobic glycolysis and oxidation) 2. The accumulation of metabolic by products such as lactate. 2

3. 3. The nervous system and 4. The failure of muscle fiber's contractile mechanism 3

4. Energy systems and fatigue : PCr ( phospocreatinine ) depletation : It is useful in anaerobic condition to rebuilt high energy APT as it is used and thus maintain body's ATP stores. Study on human thigh muscle show that during repeated maximal contraction fatigue coincides with PCr depletion. 4

5. Although ATP is directly responsible for the energy used during activities, it is depleted less rapidly than PCr during muscular effort because ATP is being produced by other systems. Body's ability to quickly replace the spent ATP is hinderd . ATP use continuous ,but the ATP- PCr system is less able to replase it. Thus, ATP levels also decreases. 5

6. At exhaustion, both ATP and PCr may be depleted . It now appears that P, which increases during intense short term exe rc ise because of the breakdown of PCr , is a potential cause of fatigue . S o warm up is needed before ex ercise. 6

7. Glycogen depletion : Other reason of ATP maintainance is aerobic and anaerobic breakdown of muscle glycogen. In event lasting longer than a few seconds, muscle glycogen becomes the primary energy source for ATP synthesis. Glycogen reserves are limited and depleted quickly. 7

8. Musc l e glycogen can be limited factor even during mild effort . Muscle glycogen is used more rapidly during the first few minutes of exercise than in the later stages .(warm up ) Sensation of fatigue in long term exercise co-insides with the decrease of muscle glycogen 8

9. Depletion in different fiber types Muscle fibers are recruited and deplete their energy reserves in selected patterns .The individual fibers most frequently recruited during exercise may become deplete of glycogen The pattern of glycogen depletion from Slow Twitch(ST) and Fast Twitch(FT) fibers depends on the exercise intensity. ST fibers are first fiber to be recruited during light exercise. 9

10. Depletion in different muscle groups In addition to selectively depleting glycogen from ST or FT fibers , ex erci s e may place unusually heavy demands on selected muscle groups. A study shows that the ankle extensor muscle are more likely to become depleted during distance running than are the thigh muscles, isolating the site of fatigue to the lower leg muscles. 10

11. Depletion & blood glucose M uscle glycogen a lon e can't provide enough carbohydrate for exercising lasting several hours. G lucose delivered by the blood to the muscles contributes a lot energy during endurance exercise. In the beginning relative little blood glucose is required but in later stages , blood glucose may make a longer contribution . 11

12. Effect of depletion on performance Endurance perform ance improve when the muscle glycogen supply is elevated before the start of activity . Glycogen depletion and hypoglycemia limit performance in activities lasting 30 min or longer . Fatigue in shorter events more likely result from accumulation of metabolic by products e . g . lactate and H+ within the muscles . 12

13. Metabolic by products and fatigue L actic acid is a by product of anaerobic glycolysis. Most people believe that lactic acid is responsible for the fatigue and exhaustion in all types of exs , lactic acid accumulate within the muscle fiber only during a relatively brief hig h ly intense muscular effort . E g . marathon runners , may have near resting lactic acid levels at the end of the race despite their exhaustion . In this , fatigue is caused by inadequate energy supply , not excess lactic acid . 13

14. Sprints in running , cycling and swimming call lead to large accumulation of lactic acid . These activities are of short duration and high intensity and they depend heavily on anaerobic glycolysis and produce large amounts of lactate and H + within the muscles Only lactic acid is not the cause of fatigue , the lactic acid dissociates , converting to lactate and causing accumulation of H+ ions. 14

15. H+ ions causes muscle acidification resulting in acidosis . The cell and body fluid posses buffers such as bicarbonate (HCO3) , that minimize the disturbing influence of H+ . Without buffer pH gets lower by H+ . Because of body's buffering capacity , the H+ concentration remain low even during most severe exercise , allowing muscle pH to decrease from a resting value of 7.1 to 7.3 and no lower than 6.6 to 6.4 at exhaustion . 15

16. Change in pH affects energy production and muscle contraction . An intracellular pH below 6.9 inhibits the action of phospho fructokinase , which is an glycolytic enzyme, showing the rate of g l ycolysis and ATP production . At pH of 6 . 4 , the influen c e of H+ stops and further glycogen breakdown causing rapid decrease in ATP and ultimately exhaustion, H+ decrease muscle contractile force . 16

17. Major limit of performance and the primary cause of fatigue is low muscle pH. Even when normal pH is restored blood and muscle lactate level can remian quite elevated . Blood lactate measurements are being used to decline intensity and volume of training needed to produce an optimal training stimulus. But these measurements depend on the rates of production, diffusion and oxidation 17

18. Neuromuscular Fatigue: Evidence says that under some circumstances, fatigue may result from an inability to activate the muscle fibers The nerve impulse is transmitted across the neuromuscular junction to activate the fiber’s membrane and it causes the fiber’s sarcoplasmic reticulum to release calcium, which initiates muscle contraction 18

19. Following are the neural mechanisms that could disrupt this process and possibly contribute to fatigue: Neural Transmission: In early 19 th century, studies showed failure of nerve impulse transmission in fatigued muscle. 19

20. This is because of prevention of nerve impulse transmission to the muscle fiber membrane This failure may involve one or the more of the following process: 1. The release or synthesis of ACh , the neurotransmitter that relays the nerve impulse from the motor nerve to the muscle membrane might be reduced 20

21. 2. Cholinesterase, the enzyme that breaks down ACh once it had relayed the impulse, might become hyperactive, preventing sufficient contraction of ACh to initiate an action potential 3. Cholinesterase activity might become hypoactive (inhibited) allowing ACh to accumulate excessively, paralysing the fiber 21

22. The muscle fiber membrane might developa higher threshold Some substances might compete with ACh for the receptors on the muscle membrane without activating the membrane 4. Potassium might leave the intracellular space of the contracting muscle and decreasing the membrane potential to half of its resting value 22

23. Most of these are related to neuromuscular disease ( eg . Myasthenia Gravis) 23

24. CNS CNS also might be a site of fatigue. Some evidences are in favor of this and some are against Studies showed that when a subject’s muscle appeared to be nearly exhausted, verbal encouragement , shouting or even direct electrical stimulation of the muscle could increase the strength of muscle contraction This shows that limits of performance may be psychological 24

25. Energy Production: Fink Colleagues demonstrated that in addition to increasing body temperature and heart rate, exercise in the heat also increases O2 uptake, causing the working muscles to use more glycogen and to produce more lactate compared with exercise in the cold This leads to greater use of muscle glycogen and production of more lactic acid, this causes fatigue 25

26. Febbraio hypothesized that increased muscle temperature impairs skeletal muscle function and metabolism, which can lead to fatigue 26

27. Chronic Fatigue When weight drops below a certain optimal level, in an athlete, he is likely to experience performance decrements and increased incidence of illness and injury. Performance decrements can be attributable to many factors like chronic fatigue which is after accompanies major weight losses. The exact cause of chronic fatigue is still unknown. 27

28. In chronically underweighted athlete, there are more chances of fatigue Both neural and hormonal components are involved in the phenomenon of overtraining In most cases, the sympathetic nervous system appears to be inhibited and parasympathetic system dominates 28

29. Immune as well as hypothalamus functions are impaired and these leads to symptoms of chronic fatigue. Almost all energy derived from carbohydrates. The carbohydrate storage in muscle, liver and extracellular fluid accounts for approx 2,000kcal of stored energy. Inadequate diet while hard training carbohydrate energy stores become depleted. 29

30. Important thing in athlete is liver and muscle glycogen level decreases, which reduce blood glucose level. Combined effect of these lead to chronic fatigue and decline in performance. After this, body starts using protein stores as energy substrates. In this way, gradually muscle proteins also deplete. 30

31. Chronic fatigue can be because of immune system dysfunction. Other symptoms are prolonged debilitating fatigue, sore throat, muscle tenderness or pain. 31

32. Overtraining When the training load is too intense or the volume of training exceeds the body’s ability to adequately recover and adapt, the body experiences more catabolism (breakdown) than anabolism (buildup). In other terms, it is characterized by a sudden decline in performance and physiological function that cannot be recover by a few days of reduced training or rest and dietary manipulation. 32

33. Effects of Overtraining Main effect is decline in performance if training is continued 33

34. Symptoms Athlete can sense a loss in muscle strength, coordination and maximal working capacity Changes in appetite and body weight loss Sleep disturbances Irritability, restlessness, excitability, anxiousness Loss of motivation Lack of mental concentration Feeling of depression 34

35. Causes Emotional and physiological factors Hans Selye studied that as physiological distress increases, anxiety increases and that leads to break down of the stress tolerance Emotional demands of competition, the desire to win, the fear of fatigue, unrealistically high goals and other’s expectations can be sources of intolerable emotional stress. 35

36. Overtraining is typically accompanied by a loss of competitive desire and a loss of enthusiasm for training. Physiological factors responsible for this are not fully understood. 36

37. Autonomic nervous system overtraining: Sympathetic overtraining can lead to: - Increased resting heart rate - Increased blood pressure - Loss of appetite - Decreased body mass - Sleep disturbances - Emotional instability - Elevated basal metabolic rate 37

38. Parasympathetic overtraining: - Early onset of fatigue - Decrease resting heart rate - Rapid heart rate recovery after exercise - Decreased resting BP Symptoms of sympathetic overtraining are commonly seen. No one can say that these particular symptoms are there so it is overtraining. 38

39. Hormonal response to overtraining syndrome: There is marked disturbances in endocrine function accompany the excessive stress. ↑ t raining= ↓ thyroxin ↓ testosterone ↑ cortisol Ratio of testosterone and cortisol regulates anabolic process in recovery . So changes in the ratio is the important indicator of the syndrome. 39

40. Decrease in testosterone and increase in cortisol leads to more protein catabolism In overtraining syndrome, cortisol decreases in both, during resting and during exercising In this syndrome, increased level of urea in blood because it is produced by breakdown of proteins, which indicates increased proteins catabolism and decreased body mass. 40

41. Increased heart rate and BP is because of increased epinephrine and norepinephrine . 41

42. Immunity and Overtraining: Overtraining suppresses the immune system. It decreases the levels of lymphocytes and antibodies, which decreases ability to fight against infection and increases risk of other complications. 42

43. Management: Cancer related fatigue management: During palliative care, low intensity exercise are given to improve quality of life Patients who receives marrow or stem cell transplants are given aerobic interval training During chemotherapy and radiation therapy, home-based exercise programs are given In prostate cancer patient, who is under going androgen deprivation therapy, strengthening exercises are beneficial 43

44. In beginning, low intensity and shorter duration exercises are beneficial Initially, 20-30 min sessions, 3-5 times per week Study showed that exercise more than 60 min/day, increases fatigue in cancer patients Exercise should be used cautiously in the presence of bone metastasis, low platelet counts, anemia and fever 44

45. In some cases, modified exercise regimen can be recommended. Example: Neutropenic patient should avoid environments with high risk of infection (gym or swimming pools) 45

46. Fatigue management in multiple sclerosis: Aerobic exercises: light to moderate, cycling for 40-60 min, 3 times/week, 2-6 months This helps in decreasing general, physical and psychological fatigue symptoms, after 8 weeks of moderate intensity aerobic activity 2 times/week. 46

47. Traditional resistance training: Improves general symptomatic fatigue after 12 weeks, 2 times/week resistance training program (8-15 RM); Decrease fatigue overall or specifically physical and psychological fatigue after 8 weeks of moderate intensity resistance training, 2 times/week (6-15 RM) 47

48. Combined training programs: 5-8 weeks, aerobics and resistance training, moderate to high intensity exercises, improvement after 8-10 weeks of 2-3 times/week Other exercise: Sports, yoga, body weight support treadmill training, cycling, pilates 48

49. Aquatic exercise: Pool therapy, hydrotherapy, 60 min session, 3 times/week, 4-8 weeks 49

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51. Tai Chi: Everyday for 2 months 51

52. Qigong: 90 min, 2 times/ week, for 20 weeks 52

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54. Cooling therapy: Cold-vest with active cooling (7 ⁰ C, 60 min) Lower body in water at 16-17 ⁰ C for 30 min It can be given before, during or after activities 54

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56. Pulsed electro-magnetic devices: Wearing an active, low-level, pulsed electromagnetic field device on one or more acupressure points daily for up to 4-8 weeks 56

57. Fatigue management programs: They are interactive group sessions and activities. FACETS- Fatigue: Applying Cognitive behavioral and Energy effectiveness Techniques to lifestyle. They are based upon a conceptual framework integrating elements from cognitive, behavioral, social-cognitive, energy effectiveness, self-management and self-efficacy theories 57

58. It is given by occupational therapists, nurses or physiotherapists 90 min session/week, for 6 weeks 58

59. Energy conservation interventions: Modifying and prioritizing activities, rest, self-care, ergonomics, environmental modification Mindfulness-Based interventions: Meditation, relaxation, breathing techniques, yoga, Tai-Chi , Qi-gong 59

60. Cognitive and psychological interventions: Tasks given to improve attention, communication and memory 60

61. THANK YOU 61