PT on the Net Research

Muscle Size Asymmetry


Question:

I have a male client who has made considerable gains in his workouts, yet has a noticeable size difference in his pecs. No matter what we try, we cannot seem to balance them out. Do you have any suggestions?

Answer:

I'm not sure from the information you've provided what you've tried to "balance them out" but certainly do not simply add more sets of chest presses/exercises to the smaller side. Function should always precede aesthetics, and this is a sign of something wrong functionally. Muscle asymmetry is fairly common, and there are a few points to consider here:

  1. WAS THERE EVER AN INJURY TO THE HEAD/NECK?
    • Muscles can only function when their corresponding nerves tell them to. The pec major is innervated by the Lateral and Medial Pectoral nerves which stem from C5, C6 and C7. If your client has ever suffered from a head or neck injury, even what may be perceived as a minor one, there may be some residual damage that is disrupting electrical communication, thereby preventing the desire growth. A skilled Orthopedist, Chiropractor or Physical Therapist should be able to help.
  2. WAS THERE EVER AN INJURY TO THE SHOULDER JOINT OF THE SMALLER PEC?
    • The joint on the smaller side may not be stable (i.e. hyper/hypo mobile due to overuse and/or injury). When this occurs, the body INHIBITS the strength of the prime movers around the joint so that they do not perpetuate any further damage to that joint. An inhibited muscle certainly will not grow as well as a healthy muscle! The professionals listed above could also help.
  3. ARE THERE ANY GROSS STATIC AND/OR DYNAMIC POSTURAL DISTORTION PATTERNS?
    • You may notice that the shoulder on the side of the smaller pec is not in its optimal posture when standing or exercising. UPPER CROSSED posture (characterized by a forward head and rounded shoulders) may be a factor here. For example:
      • Statically when standing relaxed:
        • Does the shoulder on the side of the small pec appear to be level from the front?
        • Lined up with the ear from the side?
        • Is the scapula resting flat and secure on the rib cage?
        • Is the elbow pointed straight back?
      • OR...
        • Is the shoulder elevated?
        • Rounded forward and lined up with the cheek bone instead?
        • Is the scapula winging out?
        • Is the elbow pointed out to the side a bit, suggesting internal rotation?
      • Dynamically: you may notice that the shoulder on the smaller side tends to protract and/or elevate excessively and prematurely during exercises such as pull-ups/downs, overhead presses and rows, etc.
    • The posture of the joint can tell you a lot about how healthy/unhealthy the muscular balance and flexibility of the joint are. Muscles prone to tightness at the shoulder girdle are listed below. A skilled Massage Therapist and/or Neuromuscular Therapist as well as a sound corrective flexibility/exercise program should help restore balance. (See the PTN Exercise Library for help.)
      • Pectoralis Minor
      • Pectoralis Major
      • Latissimus Dorsi
      • Teres Major
      • Upper Fibers of the upper Traps
      • Levator Scapulae
      • Sternocleidomastoid
  4. HOW WELL DOES YOUR CLIENT LIVE?
    • Does he...
      • Get 9 hours of sleep per night (at least between 10pm-6am)?
      • Drink 1/2 his bodyweight in ounces of pure water daily?
      • Eat organically for his Metabolic Type?
      • Manage stress well?

All of these factors can/may be playing a role in what you've described. It is important that we as health and fitness professionals stop thinking of the body simply as a system of levers and pulleys and begin to realize and educate ourselves on the fact that the body is the most complex machine on the face of the earth - where NOTHING occurs in isolation of itself!