What Happens When You Lose Fitness?

Nothing is permanent in the world of fitness. Your body is constantly changing, and with enough practice, it can adapt to become quicker and more powerful. However, the converse occurs when the training stimulus is eliminated, and fitness decreases. Every athlete would benefit from having a greater grasp of detraining, including what it is, why it occurs, and how quickly it happens.

Your body is incredibly adept at distributing resources. This is the fundamental reason why training helps you get faster. The internal balance, or “homeostasis,” is disturbed by the stress of frequent exercise. In response, resources are automatically assigned to adapt, and adaptation takes place. A new equilibrium is attained together with an improvement in physical capability, or an improvement in fitness.

A reduction in or elimination of training might upset the delicate state of homeostasis. Since maintaining the physical adaptations of fitness requires energy and resources, the body diverts these resources if they are not required. When you stop exercising, your body eventually finds a new balance and declines in physical capabilities. This is well-known You eventually get slower as a result of detraining.

When Does Detraining Occur?

Detraining is a necessary step in the training cycle. Minor detraining happens during rest weeks or while you’re tapering for an event, but the gains in performance that come with recovery surpass it. Detraining happens more significantly in the offseason when a thorough recovery allows for better fitness gains in the upcoming months. In certain situations, detraining is temporary, deliberate, and beneficial.

On the other side, the detraining that results from lengthier gaps from conditioning can be ineffective. Complete detraining can significantly reduce your fitness without providing any actual benefits, potentially undoing the gains you’ve made after a lot of effort. Fortunately, it usually doesn’t take much to prevent these consequences, and the more fit you were previously, the quicker it is to recover.

What Happens in the Body During Detraining?

Detraining is the exact opposite of training since it causes all of the performance-enhancing adaptations that occur to make you faster to gradually reverse. The various impacts of detraining also happen at different rates and to diverse degrees, much as the advantages of training.

Since VO2 max significantly drops in the first month of inactivity, aerobic capacity is the first thing to be impacted. Declines in blood volume, a decrease in the number of red blood cells, and a general loss in cardiac output are the main contributors to this. Your heart rate rises to make up for the decreased amount of oxygen getting to your muscles, which raises your RPE (rate of perceived effort) all around.

These aerobic declines effectively shift some burden to your anaerobic system, and blood lactate levels increase as a result. Muscle glycogen stores plummet, as do the levels of enzymes responsible for synthesizing them, making your body less efficient at fueling muscles during exercise. The practical result is a significant decline in your FTP.

After a few weeks, peripheral cardiovascular systems also experience accelerating effects. Capillary density drops, as does mitochondrial density and the levels of oxidative enzymes. Muscular losses cause a drop in peak power output and the size of the heart and pliability of the left ventricle decrease. Improvements in blood pressure resulting from exercise reverse by the 12th week of inactivity, and ventilatory function falls up to 14% from its trained maximum after a few months.

Finally, some muscle fibers convert from type 2a to type 2b, becoming more reliant on anaerobic metabolism. This can ironically make anaerobic efforts feel easier as you detrain, but don’t mistake this paradoxical effect for an improvement in fitness. Eventually, with a sufficient decrease in training stimulus, your body almost completely reverts to its untrained state.