Posted in Fit basics

Weights, Cables or Machines part II

In the first part of this article we pointed out two simple facts:

  • muscles make no difference between forces originating in weights, cables or machine levers
  • torques that external forces produce in joints is what matters

T = F · L · sin(A)

So let’s see how this reflects to free weight exercises.

Put gravity to good use

When we think about free weights such as dumbbells and barbells, the obvious constraint is that the force they produce is always pointed strictly downwards; we call this force “weight”. This is not a huge limitation because one of the guiding principles in human body design is the ability to lift heavy objects from the ground. Deadlift is the obvious confirmation of that – there is no other movement using which any human body would be able to move more weight than in deadlift.

Free weight exercises tend to feel quite comfortable as they do not prompt joints to be put into awkward positions. The best among them are such that they exploit the natural bio-mechanical advantages that our bodies possess. Deadlift and squat are obvious examples of such movements. If you decide to educate yourself more deeply into squat mechanics you will come upon an interesting fact that both quadriceps and hamstrings in our legs contribute to pushing the combined weight of the upper body + barbell upwards. Consequently, strength of both quads and hams is equally important not merely for the ability to lift the weight, but also for keeping the knees and hips in healthy condition for decades. But how is that possible? Aren’t hamstrings and quads antagonists to each another? Well, that is one of the ingenious details of body construction but explaining it requires a bit more analysis than is appropriate for this article; we recommend Starting Strength by Mark Rippetoe as an excellent resource.

Let’s think about how is it possible that our bodies are able to bear huge loads without over-stressing any particular joint or muscle. Is it by using some kind of magic? Probably not. The trick is that when put under stress we intuitively perform so called “compound movements”. They are such that no single muscle or joint is isolated at any given moment. Thus the whole weight is never put exclusively on a single “component” within the body but is spread over many synergistic structures instead. And this is precisely the reason that compound exercises such as deadlift and squat are by far the best ones for building overall strength, power and muscle mass.

Now, that’s fine but in training we sometimes need to accentuate some of the muscles more than others, be it for corrective, aesthetic of sports specific purposes. In that case free weights might be a great choice, if one can put the body in such position that the targeted muscle can be exercised optimally with the weight pulling downwards. For instance, front delts can be isolated quite nicely using a pair of dumbbells in Front raise. But isolating some other muscles to the same extent would require a trainee to put the body into some awkward position, which would either feel quite uncomfortable and/or limit the effective range of motion.

As an example of exercise that is sub-optimal if performed with free weights, let’s take a look at Preacher bench curl mechanics (your homework from the part one of this article). Sitting at the preacher bench with your arms resting on a soft pad feels cushty and there is no stress in the lower back, but unfortunately at the top position the line of force passes almost right through the elbow joint. So there is no torque in the elbow that biceps muscle needs to resist. Would you need to squeeze the biceps hard at the top? No. You are simply balancing the forearm as a stick. You could hold a dumbbell all day long in this passive position without ever feeling tired.

The way Preacher bench curl is performed more often these days is one of the solutions to this biceps squeezing problem – lifters use either a special preacher bench with levers that provide constant resistance, or they use a standard preacher bench or a knee as an elbow support but with cables from a cable rack providing resistance. That way the line of force doesn’t pass close to the elbow at the top, so muscle needs to work with maximal effort all the way up. This trick of substituting cables for free weights can be applied to most other exercises with great effect, which will be discussed in more detail in part three of this article.

Yet another simple solution for building pronounced peaks is to pump them up by good old concentration curls. It works by not letting the forearm to reach true vertical, so biceps has to pull really hard at the top. Voila!

Reality bytes

While some exercises might simply not be especially effective if performed with weights, unfortunately there are nasty ones with inherent and uncomfortably high potential for hurting you really badly. A typical member of that evil tribe is dumbbell flies: everything is Ok in it if you are able to control the weights at any moment, which becomes the harder the lower you let your arms go. But what would happen if you miscalculated the weight and range of motion, and you suddenly loose control at the lowest position? The dumbbells would start to pull your fully stretched arms even more downwards, with very long lever arm and the angle of attack approaching 90’… so the more those heavy weights managed to stretch your poor shoulders, the higher the torque, and the less control you would have. Snap!

You simply do not want to find yourself is such position. Avoid exercises which can cumulatively put even more stress on your joints and muscles if anything goes wrong. They are typically those ones in which you handle free weights above your body or your head, and your back is fixed – not only are your shoulders and elbows in risk of being overstretched, but you also provide an unfortunate cushion for the weights. If barbell bench press now comes to mind, you got the point; it’s hard to find a single “gym fails” video on YT without a horrible bench press accident in it.

The rule of survival is simple. Use squat cage rack when you squat and safety catches when you bench press. If you use free weights in your training routine, make sure that they can fall down safely without hurting you. And please don’t value the floor more than your own body. Gym owners are well aware of the fact that weights have a tendency to be dropped down hard from time to time. And even if your gym lord is of the raging bull sort, your head is going to be better off anyway than if a dropped 100 pound dumbbell landed on it.

Whenever you take heavy weights in your hands, always go through a mental safety drill and think for a second how you would let them go if you suddenly loose control.

Everything keeps pounding in my head
Can’t free my soul til I
Learn to let go
I’m losing control
Say it ain’t so
Throw my hands up
And learn to let go

Gee thanks for such educative lyrics, Welshly Arms bros!