Body symmetry is exceptionally important for bodybuilding and weightlifting - but what many people don't realize is that body symmetry also effects many other things too.
MUSCLE IMBALANCE = BACK PAIN
For example, did you know that pregnant women develop overly strong back muscles during the pregnancy? The reason is so they can support the extra weight of a baby and all the extra water weight, and that with time this leads to back pain - even after the baby has been born.
Now you might think, wait, why would they have back pain if their back is STRONGER? Shouldn't a strong back eliminate back pain?
Nope, and therein lies the problem. Many people don't realize that the primary source of backpain is a loss of balance between front mirror muscles and their back muscles. Often it is directly connected on a lateral level.
Examples
Small pectoral muscles = upper back pain.
Small abdominal muscles = lower back pain. (Especially since people often have weak lower back muscles in the first place.)
The reason is because the pectorals and abs are also used for balance, and if those muscles are smaller / weaker the back muscles in the corresponding mirror muscles have to work twice as hard in order for a person to maintain their balance and posture. A person with really lax muscle mirror muscles is going to have really bad posture and lots of back pain.
It is possible to have overdeveloped front torso muscles, which is exceptionally rare for the common person, but more common for bodybuilders who place too much emphasis on their front muscles because they want large pecs and abs. Since humans use their backs for so many things it is usually the back muscles which become overdeveloped and the front muscles which suffer.
AESTHETICS
Training for muscular balance is
important is also important for aesthetics. Visually people are just not attractive if they have one part of their body that is abnormally large to the point it becomes grotesque.
For example people who don't exercise properly often develop a "crooked six pack" in their abdominal region - like in the photo below.
So basically there is many ways a person can screw up the symmetry of their muscles - both front and back, and also side to side.
It can be fixed with time fortunately, but it is best to take preventative measures while you are exercising so you use proper form. The use of proper form during each exercise means you won't be sloppy and then overusing one muscle compared to the other - the constant use of one muscle and ignoring its mirror muscle will always result in an imbalance over time.
On an aesthetic level bodybuilders can see their front muscles in the mirror easily, and exercises wise it is more fun to do bench presses and bicep curls. For most people however it is the opposite. They use their back for lifting things regularly, whereas weightlifters have been taught proper form and to lift with their legs more so they don't injure their back - and thus training their backs becomes a problem.
The end result is that aesthetically different people need to do different things to correct their muscle imbalances.
STABILITY / PREVENTS INJURIES
Having strong and well balanced front and back muscles means you will have better balance and stability - which is important while lifting heavy weights as you will be using your muscles both to lift the weight and to maintain balance. Having the extra mirror muscles will take up some of the effort of maintaining your balance while the other muscles do the job of lifting the heavy object.
Trying to lift the heavy object AND maintain your balance with just the one set of muscles is going to lead to injury over time due to bad posture. In my head I see a cartoon of a man falling over and the box landing on top of him because he can't maintain his balance, but this is only a literal interpretation. The reality is that overuse of one set of muscles will cause them to eventually rip - ripped muscles is normally a good thing in bodybuilding - but in this case a rip could mean ripped ligaments, which is exceptionally painful and sometimes untreatable.
Common injuries like hernias for example can be prevented by developing better mirror muscles. It is well worth it to make the effort. Do a google image search for hernia sometime and that should scare you into exercising your mirror muscles more to correct your imbalances.
FIXING MUSCLE IMBALANCES
Overdeveloped Back
The majority of you are probably reading this because you are an average person and have back pain. So the quick answer is for you to work on your pectorals, abdominal muscles and even your oblique (side) muscles.
This means doing exercises like push ups, sit ups, and side twists to build up pecs, abs and obliques. It is a relatively easy fix, takes you about 5 - 10 minutes every day and keep doing that for several months and you should have a lot less back pain as those muscles grow. (Unless you have chronic back pain caused by something else, like a slipped disk in your spine. In which case see your doctor.)
Overdeveloped Front
If you are the opposite however, someone who has been weight training for a long time and has developed overly large front muscles and neglected your back then there is a variety of exercises you can.
#1. Take up archery (archers tend to develop overly large back muscles, so this is a quick solution to your problem if your front muscles are currently overdeveloped - see Mirror Muscles for Archery).
#2. Use any kind of pulling machine in the gym. Rowing machines work well too.
#3. Be creative and use dumbbells in pulling exercises. Exercises like reverse flies. Make sure the weights are heavy enough to challenge you.
#4. Body weight exercises that use your back muscles. Pull ups, chin ups use your back shoulder muscles and your back muscles for balance.
#5. T Flies - Bend forward at the waist so that
the back is very straight. Look down and with straight arms, slowly flap your arms. You may feel silly doing this at the gym so do it at home. Each time your arms come up to as high as they can go, really
focus on squeezing your shoulder blades together. When they come all of
the way back down, focus on stretching the back and shoulder muscles
forward.
#6. Yoga - Hold the poses for longer periods of time to stress your muscles more. Try
Ashtanga Vinyasa Yoga to get a more powerful workout.
OTHER WEIRD IMBALANCES
Biceps Vs Triceps
Pain in your biceps can mean you are overusing your biceps in your effort to get bigger - a common problem with newbs at the gym. This affliction is rare because the triceps are used in many exercises so the good news is you can easily fix it by doing more triceps exercises regularly.
Biceps may get more attention, but anyone who has been concerned over the back of the arm being flab, or just having nicely toned arms in general, will have trained their triceps.
The triceps are easy to train with exercises such as dips, overhead extension, and skull crushers but also shows results really quickly because the triceps build bulk muscle faster.
Lower Back and Abs
The lower back is probably the least trained muscle group of all. If any muscle should be trained, it is this one - but you need to exercise your abs too so you correct the imbalance without making a new imbalance.
I recommend doing abs and lats exercises FIRST during a workout so you get it over and done with. Many people do these exercises last and sometimes forget to do them. Or skip them entirely. This doesn't help them since the lower back and abs is used for core balance, and injury prevention.
Nobody is ever going to compliment you on your toned lower back, but the muscles there are exceptionally important for balance, posture and injury prevention.
Try doing alternating back extensions, either on all fours or on your belly. See photos below.
Another good one is Superman Pushups. They make look easy but they are harder than they look because most people have weak lower back muscles.
Hamstrings
Many people neglect to exercise the back of their legs. But there are man common exercises that build muscle there.
Squats
Bicycling
Lunges
Standing Leg Curls
Straight Leg Deadlift
Snap Kicks
Sprinting (especially on a sandy beach, because it works them harder)
CONCLUSIONS
Mirror muscles are exceptionally important for aesthetics, sports training, balance, strong core muscles, pain prevention and preventing injuries. I cannot emphasize the importance of
Mirror Muscle Training enough. For whatever exercise goals you have set forth for yourself, you should do complimentary Mirror Muscle Training to give yourself a physical edge.