As a cyclist, you are interested in a perfect working aerobic system, and the skeletal muscle is undoubtedly a part of this. Fortunately, skeletal muscles are very adaptive to training.
A weight lifter will not gain the same changes as a cyclist would. But, again, this is because the specific requirements are different, and so are the peripheral adaptations in the skeletal muscle.
Increased capillary density
The capillary density increases after periods of cycling training, probably due to greater oxygen demand. This oxygen demand stimulates the growth of the capillary bed.
This is a unique adaptation that prepares your body for new challenges.
The diffusing distance between blood and cells is reduced when the capillary density is increased. A shorter diffusing length makes the exchange of O2, CO2, substrates, and metabolites faster.
The increased capillary density also results in a larger surface area available for this exchange, which gives a faster flow rate through the muscle.
During maximal cycling, the trained muscle will receive a larger blood volume/min than the untrained muscle.
Like hemoglobin, myoglobin can bind, store and release oxygen. In addition, myoglobin facilitates oxygen diffusion in muscle fibers that depend on aerobic metabolism.
Cycling training increases the content of myoglobin. More myoglobin means more diffusing forces, which results in higher oxygen delivery in the skeletal muscle.
The increased number and size of the mitochondria in the skeletal muscle shows us how vital these small power fields are for oxygen transport.
There is also at the same time an increase in a wide range of oxidative enzymes, including those in the citric acid cycle.
Better use of free fatty acids as fuel
It is well-known that well-trained cyclists can cover a more significant percentage of the energy demand with free fatty acids and triglycerides as fuel. This gives the well-trained cyclist an advantage because he saves his limited glycogen stores for later use.
Even for well-trained cyclists with a low fat percent, the amount of fat available as fuel is more than enough. There is enough fuel for a very long time without hitting a gas station.
The degree of free fatty acids used is changed in the trained part of the body, for cyclists that are primarily the legs. Other body parts use the same amount of free fatty acids as before training.
Larger glycogen stores
With training, glycogen stores in the skeletal muscle will increase. However, it is crucial to notice that glycogen stores are closely related to training and dietary status.
If you train very intensely, your glycogen stores might be deficient afterward. However, your glycogen stores will increase if you eat a very carbohydrate-rich diet like pasta, rice, or bread. Carbohydrates are stored in the liver (25%), and the rest is stored in the skeletal muscles (75%). Read more about carb-loading here.