2023-06-09 by Asif Khan

Why Do We Feel Drained After Physical Activity?

When we participate in physical activities like exercise or any kind of movement, our body has to work hard to meet the demands of those activities. Our muscles play a crucial role in carrying out these tasks, and they need energy to do so. This energy is supplied by a famous molecule called adenosine triphosphate (ATP).

As we exercise, ATP is broken down to release the energy needed for muscle contractions. But, during physical activity, our muscles rely on a limited supply of ATP. As ATP levels decrease, the production of byproducts like lactic acid increases. This is one of the reasons our muscles become fatigued, signalling the need for rest to replenish ATP stores.

However, ATP depletion and an acidic environment aren't the main causes of fatigue; rather, insufficient ion concentrations near the muscle membrane hinder proper resetting.

When we move, signals from the brain reach the muscles through motor neurons, triggering the release of acetylcholine. This neurotransmitter sets off a chain of events in the muscle cell involving ions like sodium and potassium. This leads to ion movement in the muscle cell, generating an electrical signal that releases calcium, enabling muscle contraction powered by ATP.

Rest replenishes ions near the muscle membrane and relieves fatigue. Resting and giving our muscles time to recover allows them to rebuild their energy stores and repair any damage that may have occurred during the activity.

So, feeling tired after physical activity is a sign that our muscles have worked hard, used up their energy, and need time to rest and recover.