The thymus gland is known as the 'throat sweetbread' or 'heart sweetbread' depending on the part of the thymus being considered. The thymus gland has two parts. The heart sweetbread is attached to the last rib and lies near the heart, although the name may refer to its shape as much as its location.
The overall result of regular cycling is a lean, fit body with notable stamina increases. The most obvious area of muscle building during bike rides is the lower body, more specifically the legs. Cyclists build the two main muscles located in the calf: soleus and gastrocnemius. The soleus helps to lift the heel and the gastrocnemius is the prominent part of the calf that allows riders to go.
You will perform this exercise as a variation on ab crunches. The difference is that you always have both feet off the ground during these bicycle crunches. This makes bicycle crunches a bit harder, than standard ab crunches. Also, it tends to work the lower abs more. Typically, keeping your legs off the ground works the lower abs. Keeping your legs flat, on the other hand, works the middle abs. Interestingly, bicycle crunches also work the rectus abdominus muscle (upper abs). This is the highest set of ab muscles you have.