In order to know what Thoracic Outlet Syndrome is, or TOS, it’s best to know what and where you can find the Thoracic Outlet. The space between the collarbone and the first rib is known as the Thoracic Outlet.
Your body contacts the bicycle in three areas; your hands, your seat, and your feet. The relative positions of feet, seat and hands determine your comfort and efficiency on the bike. There are several variables that determine these positions; crank length, distance from crank center or bottom bracket to saddle, saddle angle, seat tube angle and saddle offset, distance from saddle to handlebar, relative height of saddle and handlebar width, and handlebar drop on road style handlebars. When these measurements are not taken seriously into consideration, pain and fatigue is inevitable during the ride.
The spine, same as our feet, gets the hardest job in our body as it is used in practically every movement we make and it takes pressure from other body parts such as from the neck, shoulders, head and our arms. As we walk, stand, sit, carry a heavy object or dance, our spine takes the pressure to keep our body erect but at the same time it also has to have the flexibility to make other kinds of movements while keeping our balance.
One of the following can be noticed when one has a bad posture: high shoulder, a forward stooping head, a rotated trunk (torso), a hunch back, a high hip, and a side-bent neck and one of the feet will be externally or internally rotated. Abnormal posture can result from trauma (like a car accident or fall), repetitive movements (turning your neck towards the monitor), and certain bad postural habits (sleeping on your stomach).