Understanding Fatigue After Daily Activities

Dr Lorna Paul,

Physiotherapist

Reader in Rehabilitation

Fatigue after daily activities

• Post-exertional fatigue is one of the main symptoms of ME

• Lots of studies of exercise tests where people manage the exercise at the time but are not followed up for 24 or 48 hours later

• Post-exertional fatigue/malaise not just after strenuous activity

• Update of study funded by ME Association

Purpose of the study

• What goes wrong within the body which leads to post exertional malaise/fatigue in ME?

• Examining three things 1) HPA function 2) autonomic functioning 3) inflammatory response

• Examining these 3 things before and after 3 different tasks 1) cognitive task 2) cycling task 3) daily task (vacuuming)

Participant Groups

4 groups of people – 30 people in each group

• ME

• MS

• Post breast cancer (within one year of end of treatment)

• Healthy controls

Immunological response to exercise

Hypothalamic-Pituitary Axis (HPA axis)

What is cortisol?

Cortisol (or hydrocortisone) is

• a steroid hormone

• released in response to stress• increases blood sugar

• suppresses the immune system

• aids in fat, protein and carbohydrate metabolism

Autonomic Function

• The autonomic nervous system is part of the peripheral nervous system

• It controls many systems subconsciously eg The ANS affects heart rate, breathing, digestion, perspiration, size of pupils

• The hypothalamus ‘central control area’ for the autonomic nervous system

• Split into sympathetic and parasympathetic nervous systems

Immunological response to exercise

Immune response

Immune cells produce cytokines which would be pro-inflammatory or anti-inflammatory

Each person attends four times

• Introduction and Induction

• 3 ‘fatiguing’ tests

a) Computer based cognitive task

b) Submaximal exercise bicycle task

c) Standardised daily physical activity task (vacuuming)

Computer based cognitive task - PASAT

• Paced Auditory Serial Addition Test• The PASAT is a measure of cognitive

function that assesses auditory information processing speed and flexibility, as well as calculation ability.

• Single digits are presented every 3 seconds and the patient must add each new digit to the one immediately prior to it.

• The PASAT is presented on CD to ensure standardisation

Submaximal exercise bicycle task

The Aerobic Power Index test is a submaximal exercise test on a static bicycle

It consists of gradual increments in power output

The test is stopped when people reach 75% of their predicted maximum heart rate (220-age)

Standardised daily physical activity task (vacuuming)

Outcome Measures – First visit

• Basic demographic details – age, height, weight, medications

• Questionnaires – eg. Hospital Anxiety and Depression Scale (HADS)

• Autonomic assessment

Outcome measures – Autonomic regulation

Outcome measures (cont)

• Heart rate and blood pressure monitoring during and after the task

• QuestionnairesSF36Checklist individual strength (CIS) - contains 20 items that measure 4 aspects of fatigue: 1. Subjective Fatigue; 2. Concentration; 3. Motivation; 4. Activity.

• Physical activity monitoring (7 days between tests)

Immunological markers - cytokines

Bloods have been taken and frozen

Still deciding on which cytokines to test

Expensive tests to do!

Lorna.Paul@glasgow.ac.uk

0141 330 6876