Fatigue is medically defined as a reduced ability to perform work and is a feeling of temporary or chronic tiredness, malaise and low energy. In most cases fatigue is caused by stress, overwork, poor nutrition and a lack of physical fitness and restful sleep. It can also occur along with a racing or rapid heart beat or tachycardia as the heart tries to pump blood faster to increase energy. The University of Maryland Medical Center notes the fatigue can be a side effects of some types of medications 34. Several disorders and diseases can also cause fatigue and tachycardia symptoms.

Stress

Stress and emotions such as frustration, grief and anger lead to raised levels of hormones such as norepinephrine or adrenaline by the sympathetic nervous system. This stress stimuli can lead to symptoms such as fatigue and an elevated heart rate. The Cleveland Clinic warns that chronic stress can lead to a consistently elevated heart rate, eventually resulting in hypertension or high blood pressure and even heart disease 2.

Infections

An illness due to an infection can lead to a fever and other symptoms such as fatigue and weakness. This can also temporarily cause tachycardia. According to the University of Illinois Medical Center, the heart rate is raised because the infection causes stress on the body 34. The brain then signals the immune system to battle the illness-causing infection and the heart rate and blood flow to the tissues are increased. The blood flow carries immune cells such as white blood cells and macrophages throughout the body.

Pacemaker

The sinus or sinoatrial node is the heart’s natural pacemaker and controls the rate of the heart’s beating. If the sinus node becomes damaged it can begin firing electrical stimuli at an elevated rate, causing a rapid heart rate called sinus tachycardia. The American Heart Association warns that abnormal firing of the sinus node can also be triggered by factors such as:

• depression
  
• anxiety
  
• anemia
  
• dehydration
  
• thyroid hormone imbalances
  
• severe blood loss,
  
• some medications 1

Heart Valve Problems

A maximum healthy heart rate is approximately 220 minus the age of the individual. However, some conditions such as heart valve problems can lead to symptoms such as tachycardia and fatigue. This occurs because the valve is unable to close properly leading to some backflow of blood. The cells of the body are then unable to receive oxygen adequately and the heart must pump faster and more forcefully to deliver blood effectively.