Physiological Effects of Warm-Up

A good warm-up produces physiological changes that prepare the body for vigorous exercise (Westcott / Warm-Up material). Most important is a rise in temperature, which accelerates many events; the cardiovascular and respiratory systems gear up; and hormone production for energy regulation increases.

Temperature effects:

1. As muscle temperature rises, metabolic processes proceed faster — for each degree Celsius of temperature increase, the rate of metabolic reactions increases by about 13% (Astrand & Rodahl, 1987). A good warm-up can raise muscle tissue temperature about 2° Celsius (about 3.6° Fahrenheit), so the body can produce energy about 25% faster after a warm-up than without one.
2. At higher temperatures, hemoglobin in red blood cells gives up more oxygen more quickly to the muscle.
3. Nerve impulses travel faster at higher temperatures and nerve receptor sensitivity increases, allowing faster movement and better coordination.
4. Muscles move more efficiently after warm-up: as temperature rises, the viscosity of the muscle protoplasm decreases, reducing resistance to contraction (actin–myosin complexes), so contraction is faster and stronger.
5. An increase in temperature stimulates blood vessels to open (vasodilatation), increasing blood flow — more oxygen and nutrients, faster removal of metabolic end products like carbon dioxide.
6. Muscle elasticity increases as muscles become warmer, which may make them less susceptible to pulls and tears; flexibility appears to increase as temperature rises, which is why stretching is more effective after a warm-up.

Other physiological changes:

1. Warm-up increases blood flow in the heart muscle, which may prevent abnormal electrical activity associated with inadequate oxygen (abnormal ECGs seen in healthy men who suddenly began vigorous exercise without a warm-up did not occur after a warm-up; Shellock, 1983).
2. The body adjusts hormone levels for energy production (insulin, glucagon, epinephrine, norepinephrine), making more carbohydrates and fatty acids available.
3. A low-intensity warm-up helps the body use more fat for fuel (Hetzler & Knowlton, 1986), which can produce a glycogen-sparing effect important for endurance athletes (helping avoid "hitting the wall").

• Metabolic reaction rate rises ~13% per 1°C of temperature increase.
• A good warm-up raises muscle temperature ~2°C (~3.6°F) → ~25% faster energy production.
• Higher temperature: more O2 released by hemoglobin; faster nerve impulses; lower protoplasm viscosity (faster, stronger contraction); vasodilatation (more blood flow); greater muscle elasticity.
• Stretching is more effective after a warm-up.
• Warm-up increases coronary blood flow (may prevent abnormal cardiac electrical activity).
• Low-intensity warm-up promotes fat use (glycogen-sparing effect).