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Subclavius

Gray's anatomy
Pectoralis Major

Riding a bike is great exercise.  There’s no doubt about that.  But, there are some parts of riding that aren’t so great.  Some of the common complaints from cyclists are low back pain, neck pain, and knee pain.  These complaints typically come from poor riding position, muscular imbalance, and/or extended amounts of time spent on the bike.  Other, less common bike injuries that I see in my clinic have to do with anterior shoulder pain and numbness or tingling in the hands and fingers.  As you will soon find out, these two issues tend to go hand-in-hand.

The bike position of the rider is dependent on a couple of variables: body shape, bike geometry, and bike setup.  For the purposes of this discussion, let’s assume that the rider is on a standard mountain bike.  Mountain bikes, in general, place the rider in a forward leaning position.  The rider’s body is sitting on a saddle and the torso of the man or woman is bent over the top tube, where the hands of the rider stabilize the torso by gripping the handlebar.  In this position, the upper body is performing a number of positional adjustments to provide comfort:  (lumbar and thoracic) spine is flexed, (cervical) spine is extended, shoulders are horizontally adducted, and arms are outstretched.  To keep the torso stabilized, your muscles grip the handlebar and apply force directed along your arms towards your shoulder joint.

The muscles that contribute to stabilizing your upper body on the bike are manyfold.  They all work synergistically to keep you fairly upright on the bicycle.  Since this article is about shoulder pain and numbness and tingling in the hands, we will narrow down the discussion to two common culprits of these problems.  Both of these muscles, pectoralis major and subclavius, are heavily involved in cycling and can be stressed to injury.

When riding a bike, the pectoralis muscles are in a shortened, flexed state.  They are large muscles that expend tremendous energy during cycling.  For most fit riders, the pectoralis muscles are strong enough to handle the load placed on them.  But, the problem arises when the pecs don’t get stretched between rides and remain in a shortened state, even when off the bike.  (Stand in the mirror and look for the shoulders to be rolled or hunched forward.  This could be a sign of tight pectoralis muscles.)

The same situation goes for the subclavius.  On the bike, the subclavius muscle is also in a shortened state.  Albeit a small muscle, the subclavius is within close proximity to some major nerves and vessels that traverse underneath the clavicle and down the arm.  When this muscle shortens, the clavicle gets pulled downward onto the subclavian artery and vein.

Tight, shortened pectoralis major and subclavius can contribute to thoracic outlet syndrome and impede lymphatic drainage of the breast.  Breast tenderness and edema are symptoms of muscle tension as well as numbness, tingling, and/or weakness in biceps, radial portion of the forearm and fingers.  Treat the pecs and subclavius by stretching.  Opposing muscles, or antagonists, such as the rhomboids, latissimus dorsi, and trapezius should be strengthened through exercise.  This balancing of strength on the shoulder joint provides stability through the entire range of motion.

I highly recommend acupuncture and massage therapy as the first line of treatment for numbness and tingling in the arm and fingers from cycling.  These are natural, drug-free therapies that can assist you in your recovery process.  See your alternative health provider and learn more about what they can do for you.  Implementing a stretching routine to lengthen the pecs and subclavius muscles and offset extended periods of time on the bike.

An example treatment at my clinic would be: