May 14, 2013 3 min read

Many exercisers measure heartbeats per minute as a way to evaluate fitness levels and progress. The greater your fitness level and the stronger your heart, the less often it has to contract, easing its workload.

Through the years, with consistent and appropriate amounts of activity, both exercising and resting heart rates can drop as much as 20-30 beats per minute.

Formulas exist to help determine what heart rates should be. However, there are numerous factors that can cause this number to change, such as stress, medical conditions and current fitness level.

Things to consider:

Diet. What you eat and drink can have an effect on resting and exercising heart rates. A common example is caffeine, which elevates both blood pressure and heart rate. Fad dieting or adjusting diet too quickly can also affect heart rate.

Carbohydrates are an especially important energy source for exercisers. If carb stores become too depleted, then fatigue sets in and exercise becomes difficult, as does maintaining your pace at a given heart rate. Exercisers remedy the situation by making sure to consume sufficient amounts of carbohydrate for the activity. On the other hand, consuming more carbs than your body needs for activity also affects heart rate as blood sugar levels rise and fall.

Smoking. Smoking causes the heart to beat faster and work harder. The nicotine found in cigarettes increases the flow of the hormone adrenaline, which in turn causes an increase in respiration, blood pressure and heart rate.

Medicine. Some medicines are designed to control abnormal heartbeats, while others can have side effects that can cause changes in normal heart rhythm. Beta-blockers, diuretics, antidepressants, cold remedies, asthma and thyroid medications are a few examples of medicines that can increase or decrease beats per minute. If changes in heart rate or rhythm follow the start of taking medication, check with your doctor.

Emotions. Stress and emotions play a large role in heart rhythm. Numerous studies show emotions such as fear, frustration, anxiety and anger cause heart rate to increase while feelings such as sadness, hopelessness, loneliness and depression decrease heart rate.

Positive emotions such as happiness, love and compassion result in smooth, healthy heart rhythms. Ongoing negative emotions increase stress hormone levels, cause blood vessels to constrict, blood pressure to rise and the immune system to weaken.

Other factors that can affect heart rate include genetics, disease, age, climate/current weather, altitude, hydration level and lack of sleep.

Marjie Gilliam is a personal trainer and fitness consultant.