Fatigue

Front 1

FATIGUE

Back 1

A decline in muscle force, contraction rate and muscular power. The impairments must be reversible in recovery as to be distinct from damage

Front 2

FATIGUE MECHANISMS

Back 2

1. Fuel Depletion

2. Accumulation of metabolic bi-products

3. Thermoregulatory

4. Neuromuscular Factors

Front 3

CENTRAL FATIGUE

Back 3

Mechanisms operating outside the muscles that inhabit activation and reduce force production. (Within the Central Nervous System, thought to prevent muscle damage)

Front 4

PERIPHERAL FATIGUE

Back 4

Mechanisms operating within the muscle that affect the ability of the muscle itself to produce force.

Front 5

TYPES/LEVELS OF FATIGUE

Back 5

1. LOCAL - in specific muscle groups

2. GENERAL - in all muscle groups

3. CHRONIC - unhealthy level of fatigue, caused by a breakdown of body's defences

Front 6

FATIGUE MECHANISM - FUEL DEPLETION

Back 6

- Intramuscular ATP

- Phosphocreatine

- Muscle Glycogen

- Blood Glucose

Front 7

FATIGUE MECHANISM - NEUROMUSCULAR EVENTS

Back 7

- Decreased firing of the Central Nervous System (CNS)

- Impaired Sodium and Potassium gradients

Front 8

FATIGUE MECHANISM - THERMOREGULATORY

Back 8

- Hyperthermia and Hypothermia

- Increased rates of dehydration

- Redistribution of blood to assist cooling

Front 9

METABOLIC BI-PRODUCTS IN ATP-PC SYSTEM DOMINANT EVENTS

Back 9

- Reduced force production

- Increased Pi - slows Ca2+ release/uptake; slows contraction speed

- Increased ADP - slows ATP breakdown and resynthesis

Front 10

METABOLIC BI-PRODUCTS IN ANAEROBIC GLYCOLYSIS SYSTEM DOMINANT EVENTS

Back 10

- Increased Lactic Acid Production and lactate levels - produced at 85% Max HR

- Increased H+ ions - inhibit enzymes glycolysis; slows rate of energy systems; slows rate of ATP resynthesis; prevents myosin cross bridges from attaching with actin.

-Pi is believed to be the largest contributor to the fatigue process in exercise of any duration.

Front 11

METABOLIC BI-PRODUCTS IN AEROBIC EXERCISE

Back 11

- Peripheral fatigue - less force

- Increased lactate levels

- Increased H+ ions - inhibit enzymes glycolysis, slows rate of energy system, slows ATP resynthesis.

Front 12

RESPONSES DEPEND ON

Back 12

- Type, Intensity and Duration

- Fitness levels and mental state

- Muscle Fibre usage and contractions

- Bi-Product Production

- Hydration Levels

Front 13

MUSCLE FIBRES - FAST TWITCH

Back 13

- Fast reaction time that relies on PC stores

- These deplete quickly

- Reduced oxygen supply in comparison to the aerobic slow twitch fibres

Front 14

MUSCLE FIBRES - SLOW TWITCH

Back 14

- High stores of glycogen and triglycerides help produce energy

- Eventually reserves are depleted or the neuromuscular process breaks down.

Front 15

ISOTONIC MUSCLE CONTRACTIONS

Back 15

- Muscle length changes throughout a range of movement

- Concentric = Muscle shortens

- Eccentric = Muscle lengthens

- E.g. sit-ups, throwing, sports

Front 16

ISOMETRIC MUSCLE CONTRACTIONS

Back 16

- No change in muscle length while force is developed.

- Can cause in increase in blood pressure

- E.g. Plank hold, wall sit

Front 17

ISOKINETIC MUSCLE CONTRACTIONS

Back 17

- High speed contraction through a full range of motions.

- Needs specialist training equipment.

Front 18

FATIGUE IN ANAEROBIC ENERGY SYSTEMS

Back 18

- Depletions of ATP and then PC are the most common causes of fatigue in the ATP-PC system.

- Fuel depletion does not cause fatigue during the anaerobic glycolysis system.

Front 19

FATIGUE IN AEROBIC ENERGY SYSTEM

Back 19

Depletion of glycogen stores, the fats.

Front 20

LACTATE INFLECTION POINT

Back 20

The last point of balance before lactate production exceeds lactate removal