Biology

1. Muscle Fatigue
Hellenic Claire S. Flores

2. Muscle Fatigue
- Decline in muscle force
generated over sustained periods
of activity or due to pathological
issues

3. Causes
• Ion imbalance within muscle
• Nervous Fatigue and Loss of Desire
• Metabolic Fatigue
• Exercise and Aging
• Lactic Acid Accumulation

4. Effects
• Muscle Ache
• Burning
• Rapid Breathing
• Nausea
• Stomach Pain

5. Ion Imbalance
• Contraction of a muscle requires Ca ions to
interact with troponin, exposing the actin
binding site to myosin head.
• Osmotically active molecules outside the
muscles are lost through sweating
• Difficult for the required Ca ions to be delivered
to muscle fiber

6. Nervous Fatigue and Loss Of Desire
• Nerves are responsible for controlling the
contraction and force of muscles

7. Metabolic Fatigue
• Accumulation of metabolites from Mg ions,
induce fatigue by interfering with release of Ca
ions
• Reduction in sensitivity of troponin to Ca ions

8. Exercise and Aging
• With sufficient training, the metabolic capacity
of a muscle can change delaying the onset of
muscle fatigue
• With aging, levels of ATP, CTP, and myglobin
begin to decline, reducing muscle’s ability to
function
• Muscle fiber shrink or lost

9. Lactic Acid
• Byproduct of anaerobic respiration which
strongly contributes to muscle fatigue

10. • Pyruvate produced by glycolysis is converted
into additional ATP molecules in the
mitochondria via Krebs Cycle
• Pyruvate made in the cytoplasm is normally fed
into the mitochondria, where it is burned
completely to carbon dioxide
• When mitochondria are damaged and poisoned,
and do not work well, they will not be able to
keep up with the inflow of pyruvate
In Aerobic Respiration

12. Lactic Acid Accumulation
When you exercise, your body uses oxygen to
break down glucose for energy producing ATP
required for muscle contraction.
Intense exercise, there may not be enough oxygen
available to complete the process, so a substance
called lactate is made.
• Reduced circulation to muscle may result in
glycogen depletion
▫ Reducing endurance capacity

14. • With insufficient oxygen, pyruvate cannot enter
the Krebs cycle and instead accumulates in the
muscle fiber.
• Lactic acid accumulation reduces pH decreases to
about 6.4-6.6, producing stinging feeling in
muscles when exercising
In Anaerobic Respiration

15. • Because the bloodstream cannot deliver it as fast
as it required. Lactic acid is transported to the
liver where it can be stored prior to conversion
to glucosin the presence of oxygen via the Cori
Cycle
• The amount of
oxygen required to
restore lactic acid
is “oxygen debt”

16. Warm-Up (20 minutes and half an hour)
-a session which takes place prior to physical activity
• Increasing your breathing and heart rate
• Increasing the energy-releasing reactions in the
muscles
• Increasing blood flow to the muscle to supply them
with more oxygen and to remove waste products

17. Cool Down
• Cool Down gradually returns your body to its
normal heart rate
• It disperse lactic acid (poison) which is produced
during exercise this help prevent muscle soreness
• Helps you to return to resting heart rate quicker
• Pays back oxygen debt