Unit 9: Fatigue

Question 1

Define fatigue in sports

Answer 1

A reversible, exercise-induced decline in performance.

Question 2

Outline the different types of fatigue

Answer 2

Peripheral fatigue: develops rapidly and its caused by reduce muscle cell force
- Energy delivery
- Accumulation of metabolic by-products
- Fatigue and failure of the muscle contractile mechanism

Central (or mental) fatigue: develops during prolonged exercise and is caused by impaired function of the central nervous system (brain and spinal cord)
- Response time
- Decision
-Coordination

Question 3

Distinguish between high-intensity and endurance activities

Answer 3

High-intensity exercise:
- Vigorous (full of energy)
- Bout of intense activity (short) → may last for less than a second, or as long as 1–2 minutes
- Major source of energy: anaerobic processes (ATP-PC and lactic acid system)
- Maximum speed and strength
- Example: interval training, plyometrics, 400m race, Olympic lifting.

Endurance:
- Prolonged sessions
- Low or medium intensity activity
- May last from minutes to hours
- Major sources of energy: aerobic processes (cell respiration and beta oxidation)
- Example: leisure cycling, jogging, marathon.

Question 4

Discuss causes of fatigue in different types of activity or exercise

Answer 4

Peripheral fatigue:
–> High-intensity activities: depends on the rate of…
1. Depletion (reduction) of energy sources (creatine phosphate and ATP)
2. Increase in levels of by-products of exercise: lactate and H+ ions.

–> Endurance activities include:
1. Depletion of muscle and liver glycogen reserves → long-term, glucagon is used and reduces glycogen storage
2. Reduction in Ca2+ release and depletion of acetylcholine: inhibit muscle contraction
3. Dehydration → causes cardiovascular drift. Person becomes dehydrated during prolonged exercise, they also get hotter and experience a greater increase in heart rate and a lower cardiac output
4. Electrolyte loss: Lost in sweat along with water → Important to conduct electrical impulses, without them nervous conduction decreases
5. Overheating: increases glycogen depletion

Central (mental) fatigue:
–> Failure of neural transmission: limit exercise as a protective mechanism of the brain
- Coordination lowers
- Reaction time rises

Question 5

Discuss recovery from fatigue after sports

Answer 5

Different aspects of recovery can occur at different rates, and recovery rate also depends on the
type of activity (high-intensity, team sports or endurance).

→ Removal of by-products:
Excess post-exercise oxygen consumption (EPOC): paying back O2 debt
1. ALACTACID DEBT STAGE:
a. Resynthesize muscles’ store of ATP and CP → 4 liters of O2 to do it in 3 minutes
b. Replenish myoglobin stores in the muscle
2. LACTACID DEBT: Removal of lactic acid (1-2 hours)

→ Replenish the fuels
Replacement of muscle and liver glycogen stores:
1. After intense aerobic exercise
2. Achieved greatly with carbohydrate ingestion → 1–2 days

Question 6

RECOVERY DEFINITION:

Answer 6

Restore body to pre-exercise state

Question 7

O2 DEFICIT definition

Answer 7

Not enough O2 to produce ATP → anaerobic systems catch up with this

Question 8

What happens when there is an increase in levels of by-products of exercise?

Answer 8

1. Cause low pH in cells, so enzymes denature and reduced energy.
2. Poses a problem in RECOVERY → (Protein’s vital role in the recovery process by replenishing energy stores and repairing damaged tissues)
3. Causes pain