Our brains and fatigue

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Information about Our brains and fatigue

Published on October 24, 2016

Author: UniversityofCalgary

Source: slideshare.net

1. Our Brains and Fatigue Guillaume Millet Professor, Faculty of Kinesiology October 4, 2016

2. Welcome  Webinar series by University of Calgary scholars  Information presented is a summary of the scholars’ research  Please submit questions throughout the duration of the webinar  Keep the conversation live on Twitter during the webinar using #exploreUCalgary

3. Welcome  Professor at the University of Calgary’s Faculty of Kinesiology  Head of the Neuromuscular Fatigue Lab within the faculty’s Human Performance Laboratory  Research interests are in the areas of exercise physiology, neuromuscular function and fatigue Guillaume Millet

4. Physiological, neurophysiological and biomechanical factors associated with fatigue in both:  Patients (neuromuscular diseases, cancer)  Extreme exercise www.ucalgary.ca/nmfl Neuromuscular Fatigue Laboratory

5.  Origin of acute fatigue: central vs peripheral  Central fatigue in ultramarathon and at altitude  Limits of current tools to measure fatigue  Acute fatigue resistance: does it play a role in subjective chronic cancer-related fatigue? Outline

6. …leading to an increase of psychological/energy cost to perform an exercise and/or to a decrease of maximal strength/power Changes in (physical, mental) capabilities… …whether or not the task can be sustained. Definition of fatigue

7. Intensity Maximal strength Time 100 75 50 25 0 target Neuromuscular Fatigue Laboratory Fatigue vs exhaustion

8. Intensity Maximal strength Time 100 75 50 25 0 target Neuromuscular Fatigue Laboratory Fatigue vs exhaustion

9. Duration Intensity Mode of contraction Temperature Muscle typology Continuous vs intermittent Fitness level Local vs global Sex Age Nutrition Altitude Task dependency Etc. Neuromuscular Fatigue Laboratory

10. Definition of fatigue Time Functionalcapacity Workload Fatigue Neuromuscular Fatigue Laboratory

11. Etiology of neuromuscular fatigue: central vs peripheral Neuromuscular Fatigue Laboratory

12. Central fatigue Motor planning Motor output Motoneuron pool output Motor axon conduction Neuromuscular junction Peripheral fatigue Muscle Feedback Interaction central/peripheral

13. Tools to evaluate NM function Adapted from Millet et al. Eur J Appl Physiol 2011 Sensory Ia afferent axone a-Mn axoneEMG Force/Movement Motor Cortex Spinal level Muscle Transcranial Magnetic Stimulation Peripheral Nerve Stimulation Muscle Stimulation Cervicomedullary Stimulation Central Peripheral Neuromuscular Fatigue Laboratory

14. Different types of central fatigue Fatigue =  maximal strength Cognitive Function Subjective Fatigue (RPE) Intermuscular Coordination Decrease of %VA

15. force stimulus MVC Merton J Physiol 1954 superimposed twitch resting twitch Maximal voluntary activation (nerve stimulation) From Janet Taylor, Neuroscience Research Australia

16. force stimulus MVC Merton J Physiol 1954 superimposed twitch resting twitch Maximal voluntary activation (nerve stimulation) From Janet Taylor, Neuroscience Research Australia resting twitch

17. Transcranial Magnetic Stimulation (TMS)

18. Exercise duration and central fatigue Duration Intensity Mode of contraction Temperature Muscle typology Continuous vs intermittent Fitness level Local vs global Gender Age Nutrition Altitude Neuromuscular Fatigue Laboratory

19. Central fatigue in ultra-marathon 165 km D+/-: 9000m

20. Central fatigue in ultra-marathon

21. Change in voluntary activation? PRE

22. Change in voluntary activation? PRE POST

23. Origin of fatigue peripheral fatigue (muscular) central fatigue (neural) Not as simple as that… Neuromuscular Fatigue Laboratory

24. Causes of central fatigue Adapted from Janet Taylor, Neuroscience Research Australia 3. Afferent input 1. Corticospinal drive (Supraspinal fatigue) muscle spindles excitation tendon organs inhibition recurrent inhibitiongroup III & IV fatigue-sensitive muscle afferents

25. Altitude (hypoxia) Duration Intensity Mode of contraction Temperature Muscle typology Continuous vs intermittent Fitness level Local vs global Gender Age Nutrition Altitude Neuromuscular Fatigue Laboratory

26. Vergès et al. 2012 Am J Physiol Regul Integr Comp Physiol Altitude (hypoxia)

27. 4 simulated altitudes oxygenation Cuff (total ischemia) Direct effect of hypoxia on central drive

28. 50 55 60 65 70 Bef cuff 1 min 2 min 3 min 4 min 5 min #1 #2 #3 #4 #5 #6 #7 #8 #9 #10 #11 Last cerebralTOI(%) 30% 21% 14% 9% Cerebral oxygenation Millet et al. J Appl Physiol, 2012 Direct effect of hypoxia on central drive

29. 0 10 20 30 40 50 60 70 Bef cuff 1 min 2 min 3 min 4 min 5 min #1 #2 #3 #4 #5 #6 #7 #8 #9 #10 #11 Last muscleTOI(%) 30% 21% 14% 9% Muscle oxygenation Millet et al. J Appl Physiol, 2012 Direct effect of hypoxia on central drive

30. 10 12 14 16 18 20 * #Repetitions Millet et al. J Appl Physiol, 2012 Direct effect of hypoxia on central drive

31. 10 12 14 16 18 20 * #Repetitions Millet et al. J Appl Physiol, 2012 Direct effect of hypoxia on central drive

32. Neuromuscular function during exercise Typical exercise ProblemsAdvantages Single joint, isometric contraction • Measurements during exercise • Mostly upper body and/or single-limb exercise • Isometric • Does not represent exercise performed in sports/rehabilitation. Fatigue assessment

33. Fatigue induced by 45 s sustained MVC of adductor pollicis Sheean et al. Brain, 1997, 120: 299-315 Voluntaryactivation(%)

34. Move the subject from the bike to the testing chair Other option

35. Neuromuscular function during exercise Neuromuscular function before and after exercise Typical exercise ProblemsAdvantages Single joint, isometric contraction Human locomotion : walking, cycling • Measurements during exercise • Ecological situation • Represents the reality of daily life/rehabilitation in patients. • Mostly upper body and/or single-limb exercise • Isometric • Does not represent exercise performed in sports/rehabilitation. • Installation time required to test subjects • Depending on the type of exercise, determining factors of fatigue and exhaustion (exercise cessation) might be completely misinterpreted. Fatigue assessment

36. Problem of recovery (delay) Other option

37. Effect of short recovery on muscle fatigue 3 8 PRE 20 40 60 80 100 1 2 4 8 % fatiguing exercise Recovery (min) 100 90 80 70 60 50 40 30 Torque(%initialvalue) High frequency tetanus High frequency doublet Single twitch Froyd et al. J Physiol 2013

38. Testing NMF during and immediately after whole-body exercise Neuromuscular function during exercise Neuromuscular function before and after exercise Fatigue assessment

39. Innovative ergometer VO2 TMS FNES CMEP EMG

40. Innovative ergometer

41. Chronic fatigue Chronic Fatigue: even more complicated e.g. Cancer-Related Fatigue  Severe, unrelenting feeling of fatigue, that is not improved by rest or sleep  CRF affects 70-100% of individuals with cancer  Last up to months/years post cancer (up to 30% of survivors)

42. Cancer-related fatigue Physical activity is important in fatigue management Cramp & Daniel, 2008, Cochrane Reviews VICIOUS CYCLE OF FATIGUE Fatigue is the #1 reported side effect by cancer patients and has been found to be the most distressing treatment-related symptom. • 94% of oncologists treat pain, only 5% treat fatigue -National Cancer Institute, 2007 From Nicole Culos-Reed

43. Acute neuromuscular fatigue and chronic fatigue in cancer? Andrews et al. Fatigue in Cancer 2004 Anemia – cachexia – reduction of specific force Cancer and cancer treatment Altered muscle metabolism Peripheral (muscular) mechanisms Central (brain) mechanisms  physical performance and  fatigue

44. Definition of fatigue Time Functionalcapacity Workload Fatigue Neuromuscular Fatigue Laboratory

45. Effect of workload on fatigue Time Workload Fatigue and recovery light exercise Heavy exercise Neuromuscular Fatigue Laboratory Functionalcapacity

46. Deteriorated fatigue resistance Time Functionalcapacity Workload Normal fatigue resistance Deteriorated fatigue resistance Neuromuscular Fatigue Laboratory

47. Time Functionalcapacity Fatigue accumulation Daily workloads Normal fatigue resistance Deteriorated fatigue resistance Chronic vs acute fatigue Neuromuscular Fatigue Laboratory

48. Chronic fatigue Chronic Fatigue: even more complicated e.g. Cancer-Related Fatigue  Severe, unrelenting feeling of fatigue, that is not improved by rest or sleep  CRF affects 70-100% of individuals with cancer  Last up to months/years post cancer (up to 30% of survivors) Subjective

49. PNS CNS Muscle 1. Sensory pathway from periphery 2. Copy of efferent signal to sensory cortex May contribute to chronic fatigue Neuromuscular vs subjective fatigue?

50. Hypothesized mechanisms Direct Physiologic • Voluntary activation • Muscle strength • Muscle endurance • Cardiopulmonary fitness • Body composition • Fatiguability • Muscle efficiency Biologic/hematologic • Inflammatory response • Muscle damage • Metabolic function (insulin resistance) • Endocrine function • Immune function • Anemia (brain and muscle oxygenation) Indirect Psychological • Anxiety • Depression • Distress • Cognition Social • Social interaction • Positive • reinforcement Behavioral • Sleep quantity and quality • Appetite Adapted from McNeely et al. 2010 Cancer-related fatigue

51. Hypothesized mechanisms Direct Physiologic • Voluntary activation • Muscle strength • Muscle endurance • Cardiopulmonary fitness • Body composition • Fatiguability • Muscle efficiency Biologic/hematologic • Inflammatory response • Muscle damage • Metabolic function (insulin resistance) • Endocrine function • Immune function • Anemia (brain and muscle oxygenation) Indirect Psychological • Anxiety • Depression • Distress • Cognition Social • Social interaction • Positive • reinforcement Behavioral • Sleep quantity and quality • Appetite Adapted from McNeely et al. 2010 Cancer-related fatigue

52. Makes no sense if not considering… the Big Picture Anemia Pain Activity Level Mal- nutrition Sleep Disorders Co- Morbidities Neuro- muscular Function Cachexia Inflamm. & oxidative stress Psycho-social environment Low acute fatigue resistance cannot fully explain directly chronic fatigue… but can contribute (provided it is appropriately measured) Cancer-related fatigue

53. Tailoring training to fatigue causes Testing Intervention

54. Tailoring training to fatigue causes Testing Intervention

55. Examples • Social interaction • Sleep quality and quality • Inflammatory response • Muscle damage • Metabolic function • Immune function • Voluntary activation • Cardiopulmonary fitness Outdoor endurance training late afternoon Strength training high volume Electromyostimulation • Cachexia Strength training low volume Supervised group training Low intensity endurance training High intensity endurance training

56. Take home message Goal: better understand Chronic Fatigue (e.g. CRF) to better treat it! Tailor training interventions Testing tools Training tools Tested on athletes  Ultimately enhance the quality of life of patients

57. Acknowledgements

58. gmillet@ucalgary.ca www.ucalgary.ca/nmfl Merci Guillaume Millet

59. Upcoming webinars  No Pain No Gain? The Sociology of Sports, October 6, 12-1 p.m. MST  The Race to Prevent Running Injuries, October 11, 12-1 p.m. MST  Inside the Mind of an Olympian, October 13, 12-1 p.m. MST  Knocking Out Concussions in Sports, October 20, 10-11 a.m. MST

60. Thank you Sign up for other UCalgary webinars, download our eBooks, and watch videos on the outcomes of our scholars’ research at ucalgary.ca/explore/collections

61. Other Webinar Topics For ideas on other UCalgary webinar topics, please email us at exploreucalgary@ucalgary.ca

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