Long-distance prolonged walking, especially at a high intensity or in untrained individuals, can temporarily increase markers of oxidative stress

 Long-distance prolonged walking, especially at a high intensity or in untrained individuals, can temporarily increase markers of oxidative stress. This is because prolonged or strenuous exercise can lead to increased production of reactive oxygen species (ROS). 

Here's why:

Increased oxygen consumption: During exercise, your body uses more oxygen to produce energy. A small portion of this oxygen can be converted into ROS as a byproduct of cellular metabolism.

Muscle contractions: Muscular contractions themselves stimulate ROS production in active muscle fibers.

Inflammation: Strenuous exercise can induce a temporary inflammatory response, leading to the activation of immune cells that also produce free radicals. 

However, it's crucial to understand the context:

Acute vs. Chronic Effects: While acute bouts of intense exercise can cause a temporary increase in oxidative stress, regular exercise training can actually enhance the body's antioxidant defense systems, leading to increased resistance to oxidative challenges.

Hormesis: This phenomenon suggests that moderate levels of stress, like those induced by exercise, can trigger beneficial adaptive responses in the body, including bolstering antioxidant defenses.

Individual Variability: The extent of oxidative stress responses can vary based on individual factors, including training status, age, and genetics. Trained individuals tend to experience less oxidative damage.

Not Detrimental to Health: Based on current research, it appears unlikely that rigorous and prolonged exercise, in itself, results in oxidative stress levels detrimental to overall human health. In fact, regular exercise is associated with a decreased risk of chronic diseases linked to oxidative stress, like cardiovascular disease and some cancers. 

In summary:

Prolonged walking can temporarily increase oxidative stress markers, especially at high intensity or in untrained individuals.

Regular walking can lead to adaptations that strengthen the body's antioxidant defenses.

Moderate oxidative stress from exercise is part of the adaptive process and not necessarily harmful.

High levels of oxidative stress can be detrimental, but this is usually associated with excessive or poorly tailored exercise.