PT on the Net Research

Asymmetrical Pec Growth Revisited


My male client's left lower pec is smaller than his right lower pec, and I was told it might be something to do with shoulder stability (e.g., weaker rhomboids on the left side, etc)? There is no real weakness in the left arm when bench pressing or shoulder pressing, and we change the routine around every six weeks to keep it fresh. He has no injuries. He played tennis and cricket when younger, throwing with his right arm - could this be a factor? The left shoulder feels like it wants to "pop" up when just standing normally (meaning the left trap rises slightly higher than the right trap when relaxed and standing normally). Both lats are generally tight, although the left lat appears to be slightly smaller and tighter than the right. Left scalenes also feel tighter than right. The left anterior deltoid feels much tighter than the right as well. He's slightly kyphotic, but ever since he started to train, the right pec appeared to develop slightly quicker than the left. Could it be a genetic thing? When I looked at pictures of when he was younger, the right lower pec always looked a bit bigger, but is this due to playing lots of raquet and ball sports at a young age? Is it a case of stretching out the left side of the body more (lat, deltoid, scalenes) and doing some shoulder stabilty exercises for the left side such as side planks, quadruped arm opposite leg raises? I've read Lenny's "Asymmetrical Pec Growth" Q&A and wondered what you thought of this situation. Any advice would be great!


Thanks for your question! Based on the information you provided, I would suggest a more “natural” approach to conditioning his asymmetry. Its hard to say if this is a genetic situation that lead to an acquired imbalance or simply if he exhibits a one-sidedness that has developed without regard to a genetic condition. Either way, you want to ensure it doesn’t get worse (that goes for any asymmetry). Therefore, I would stay away from exercises (especially symmetrical) that place unnecessary forces through the shoulder (bench press, side planks, traditional shoulder pressing, etc.). Traditional exercises only make you stronger for the exercise, not necessarily stronger for life movements. Therefore, start your program by first focusing on his kyphotic posture problem (which directly correlates to the shoulder-chest). Start by getting the thoracic spine to move in all planes. A simple way of doing this is to lie length wise on a three foot foam roll and perform slow shoulder-arm oscillations in all planes of motion (up-down/side-side/turning) followed by standing and performing the same thoracic-shoulder-arm movements with light weights. This multi-dimensional approach will allow you to pick what planes his entire shoulder complex is successful in (compare both right to left) and which plane(s) are not successful. If this form of assessment is not familiar to you, please consult with someone so you can learn, and your client won't end up with a serious condition in the future. A great reference for your application is Gary Gray’s videos on the Thoracic Spine and FMR of the Shoulder Complex. Both of these video will give you plenty of new tools for your client (and many others!). I hope this information “tweaks” your understanding and helps your client. Good luck!