Creatine phosphate is the immediate energy source for muscle contractions, providing a rapid burst of energy during high-intensity activities.

Glucagon is released by the pancreas during exercise, stimulating the liver to convert glycogen into glucose, thereby increasing blood glucose levels.

Homeostasis refers to the body's ability to maintain a stable internal environment, including body temperature, blood pressure, and blood glucose levels, despite external changes.

Regular endurance training leads to an increase in capillary density, which improves oxygen and nutrient delivery to working muscles.

The sympathetic nervous system is activated during exercise, leading to an increase in heart rate and blood pressure, which helps to increase blood flow to working muscles.

Type IIb muscle fibers are fast-twitch fibers that are primarily responsible for rapid, powerful movements, such as sprinting and jumping.

Acclimatization refers to the body's ability to adapt to changes in environmental conditions over time, such as becoming more tolerant to heat or cold.

Epinephrine is released by the adrenal glands during exercise, stimulating the breakdown of glycogen in muscles to provide glucose for energy.

Thermoregulation refers to the body's ability to maintain a constant internal temperature despite changes in external temperature.

Regular strength training leads to an increase in muscle mass, which improves strength and power.

Anaerobic metabolism refers to the body's ability to produce energy without the use of oxygen, such as during short-duration, high-intensity activities.

Type I muscle fibers are slow-twitch fibers that are primarily responsible for sustained, endurance activities, such as long-distance running or cycling.

Adaptation refers to the body's ability to adapt to changes in exercise intensity, such as becoming more efficient at using oxygen or clearing lactate.

Epinephrine is released by the adrenal glands during exercise, stimulating the release of fatty acids from adipose tissue to provide energy.

Acid-base balance refers to the body's ability to maintain a constant blood pH during exercise, despite the production of lactic acid and other acidic metabolites.