If you were to strengthen your biceps – through biceps curls, rows, chin-ups, etc. – without strengthening your triceps, what would happen? Would your elbow become injured over time? Would your flexibility diminish? Would all hell break loose? Or, would your biceps simply just be stronger than your biceps, and that’s it?
Well, it’d certainly be interesting to see the results of such an experiment, so whoever is willing to be a lab-rat, send me a message.
What I’m really curious about, though, is whether or not opposing muscle groups NEED to be “balanced” in order to prevent injuries. By “balanced”, I mean that both of the opposing muscle groups are used for nearly equal amounts of time(for example, row for 3 sets of 10 and bench press for 3 sets of 10), as well as having a ratio of strength that does not deviate to far from 1 (for example, being able to row and bench press a similar weight).
What the Studies Say
Some searching on the internet led me to find one study on PubMed that examined quadriceps- and hamstrings-strength in female athletes. The study sought to find associations between muscular weaknesses and the incidence of injury. In the end, researchers found that there was a correlation between weak hamstrings (compared to the strength of the quadriceps) and ACL tears in the female athletes.
Interestingly enough, the anterior cruciate ligament of the knee prevents forward “shifting” of the tibia in relation to the femur – a movement that theoretically can be prevented by the hamstrings, if contracted. Imagine an athlete – a soccer player (or footballer), for example – running across the field in an erratic manner. With all of the stops, starts, plants-and-twists, the knee is experiencing and resisting a bunch of multi-directional forces. If certain movements cause that athlete’s tibia to shift forward, the hamstrings must properly activate to take that blow. If not, the ACL takes the brunt of the force more directly.
With the study mentioned previously, it’s seen that stronger hamstrings result in less ACL tears on the field. Theoretically, spending more time in the gym to strengthen your hamstrings can pay off in the long run for your knee-health.
Let’s look at another study. Researchers tested a bunched of freshmen entering the United States Military Academy who’ve previously experienced shoulder-instability. Anterior humeral glide was what the participants experienced, which would be prevented by external rotator cuff muscles. What was specifically tested, not so surprisingly, was the participants’ rotator-cuff-strength. Based on the study I mentioned earlier, you’d think that the participants would have weak rotator cuffs. However, there was no correlation found between rotator cuff strength and incidence of shoulder instability.
What This All Means
One would assume that if a muscle fails, the ligaments take the load, so a strong muscle prevents joint-related injuries. This held true with the ACL-tear study, but not with the shoulder-instability study.
I still believe that training opposing muscle groups is a sound piece of advice to prevent injuries when going to the gym. However, I think the shoulder-instability study tells us that there’s more to preventing joint-related injuries than simply “balancing” out opposing muscle groups.
First, we need to examine posture. In our modern age, people of all ages and backgrounds are slumped over desks (in class, at home, wherever). Being stuck in a position all day where the shoulders are protracted and internally-rotated means that you’re most likely going to stay in that position later on due to tightness. When you hit the gym, do you think doing a couple sets of rows and face-pulls (which is retraction and external rotation) is going to negate the 8 hours spent stuck in the opposite position?
Faulty posture is associated with over-action/tightness of certain muscles and under-activation/looseness of the opposing muscle group. Your rowing strength might be on par with your bench pressing strength, but it doesn’t change the fact you’re in a constant state of “imaginary” bench press. Thanks, desks.
Second, we need to examine movement. If you’re experiencing pain or an injury, are you performing your movements correctly? For example, if pushups bother your shoulders, you should know that your shoulder blades should protract at the top of the movement, and retract together at the bottom of the movement. If you’re stuck in protraction the entire time, you’re only encouraging the “protracting” muscles to be continually over-active, and push the “retracting” muscles off to the side. No amount of strengthening can replace learning a proper movement!
With that said, preventing joint-related injuries due to sports and training is a multifaceted operation. Not one individual “fix” can solve an entire issue. Be proactive, not reactive.