HERS 460: Fatigue and Nutrition

Exam 1

Acute Fatigue

a decrease in maximal force or power production in response to contractile activity (aka exercise, training, competition)

General Mechanisms of Fatigue

1. Dehydration

2. Low glycogen

3. Metabolic molecules (lactate → H+ ions)

4. Poor Sleep

5. Stress

High Intensity Exercise (HIE)

a maximal bout of activity which lasts for less than a second or as long as 1-2 minutes and in which the majority of energy is derived from anabolic processes (PCr/glycolysis)

What are some main things about HIE?

• Recruits ALL fiber types

• Anaerobic pathways for ATP

• Largest ATP demand, needs fast pathways

  • Stored ATP

  • PCr re-synthesis of ATP

    • Cr Levels

  • Glycolytic re-synthesis of ATP

    • glucose as fuel → glycogen

How do each method of ATP production help HIE?

• Generates large amounts of ATP quickly

• The supple meets the demand mostly, until the intensity is higher than the supple (Lactate threshold)

Is Mitochondria used to make ATP during HIE?

Yes, but they aren’t fast producers of ATP

Type l Fiber Recruitment

• mostly mitochondria, some glycolysis and CK

• Fat is main fuel used when recruited

• Slowest glycogen depletion rate due to relying on mitochondria

Type lla Recruitment

• 50/50 mitochondria and glycolysis (CK)

• CHO/Fat are both used as fuel when recruited

• moderate glycogen depletion rate

Type 11x/b Recruitment

• mostly glycolysis (CK), some mitochondria

• main fuel is glucose when recruited

• fastest glycogen depletion rate due to the high reliability on it

How important is glycogen depletion in fatigure?

very important

Which fiber types will deplete faster?

Type ll

Why does glycogen deplete fastest during HIE?

Because HIE relies on glycolytic pathways to produce ATP, so there is a higher demand for glycogen in higher intensities compared to lower intensities that rely on mitochondria

How much glycogen is stored in the Triad?

5-15%, yet it plays a big role in ATP production

Why is the glycogen in the triad important?

Because within the triad, it is a high ATP demand and use, which is important during HIE

What happens to an athlete if glycolysis isn’t fully producing?

Fat oxidation becomes the primary ATP source. Fat oxidation is too slow for HIE, which results in bonking

What pumps used in ATP production are in the membrane (sarcolemma)?

• Na+ K+ Pump

• Ca2+ Pump

What pump used in ATP production is in the sarcoplasmic reticulum?

2nd Ca2+

What pump used in ATP production is in the sarcomere?

Myosin ATPase

What happens when there is a lack of ATP available during HIE?

Muscle contractions are not as powerful if there is not enough ATP being produced, which is caused by a lack of glycogen