GLOSSARY

Increase and decrease of heart rate refers to the factors and mechanisms that raise heart rate (positive chronotropic effect) or lower it (negative chronotropic effect).

Factors That Increase It

• Exercise and physical activity.
• The sympathetic system and adrenaline: in stress, excitement, fear, and before competition (anticipatory response).
• High temperature and fever: about 10 beats per degree Celsius.
• Dehydration: reduced blood volume compensated by a higher heart rate.
• Caffeine, nicotine, and some drugs.
• Altitude: reduced oxygen in the first days.
• Hyperthyroidism and anaemia.

Factors That Decrease It