Stress

Energy Systems

• PCr (Phosphocreatine) has a high power output, but limited capacity, making it ideal for short, high-intensity efforts.
• Glycolysis has a moderate power output and moderate capacity, making it suitable for medium-duration, high-intensity efforts.
• Oxidative Phosphorylation (OP) has a low power output, but high capacity, making it suitable for long-duration, low-intensity efforts.

Capacity and Duration

• PCr has a capacity of 10-15 seconds, with a duration of 1-3 minutes to recover.
• Glycolysis has a capacity of 30-60 seconds, with a duration of 20-30 minutes to recover.
• OP has a capacity of several hours, with a duration of 1-2 hours to recover.

Fatigue

• When PCr fatigues, ATP production slows down, and fatigue sets in.
• When Glycolysis fatigues, lactic acid builds up, and fatigue sets in.
• When OP fatigues, ATP production slows down, and fatigue sets in.

Recovery

• PCr takes 1-3 minutes to recover.

Countershock Response

• The body's countershock response is a mechanism to maintain blood pressure and prevent cardiovascular collapse.

Overtraining

• Overtraining results in decreased performance, fatigue, and increased risk of injury.

ATP Storage

• Only 2-3 mmol of ATP is stored in muscle.

ATP Breakdown

• When ATP is broken down, it produces ADP (Adenosine Diphosphate) and Pi (Inorganic Phosphate).

ATPase

• There are three types of ATPase: Ca2+ ATPase, Na+/K+ ATPase, and H+ ATPase.

Energy Sources

• The primary energy source during anaerobic alactic metabolism is PCr.
• The primary energy source during anaerobic lactic metabolism is Glycolysis.
• The primary energy source during aerobic metabolism is OP.
• Aerobic metabolism accounts for 99% of energy production throughout life.

Characteristics of Energy Systems

• The three characteristics of energy systems are power, capacity, and duration.

Lactate Dehydrogenase (LDH)

• LDH is an enzyme that catalyzes the conversion of pyruvate to lactate and vice versa.
• There are five isoforms of LDH: LDH1, LDH2, LDH3, LDH4, and LDH5.
• LDH1-2 are more predominant in slow-twitch muscle fibers, while LDH4-5 are mostly found in fast-twitch muscle fibers.
• The equilibrium enzyme meaning of LDH is that it can convert pyruvate to lactate and vice versa.
• LDH does not convert 100% of pyruvate into lactate or vice versa.
• The mass effect drives the reactions of LDH.

Muscle Fiber Types

• There are two categories of muscle fiber types: slow-twitch (Type I) and fast-twitch (Type II).