Starting Strength

occur in the thighs and legs, with bench pressing accounting for quite a few torn pecs. These muscles are attached to long bones that either move heavy weights over a long range of motion or accelerate the bones themselves very quickly over a long range of motion. In tears that occur during the bench press or the squat, the weight itself provides more resistance than the muscle can temporarily overcome and the rupture strength of the contractile tissue is exceeded. These tears can occur at any velocity of movement, even after sufficient warm-up. More commonly, running injuries occur in which the contractile strength of either the agonist or the antagonist muscle exceeds the rupture strength of the opposing component. Hamstrings, quads, and calves are torn with unfortunate frequency, and this becomes more common as athletes age and lose both muscle and connective tissue elasticity.
    The common feature of muscles that are the most subject to belly rupture is the job they do: they accelerate long bones around an angle. To do this, they produce long ranges of motion and relatively high angular velocities. Contrast this to the job of the spinal muscles: they produce and hold an isometric contraction. They are postural muscles, and their primary function is to hold a column of small bones in a constant position relative to each other. Their morphology reflects this task: the spinal muscles are long muscles, true, but they all have multiple origin and insertion points on a closely spaced, segmented, bony structure that is designed to be held in place while the appendicular structures – the arms and legs – propel it through space. The vertebral column depends on stability for its structural integrity, and though it features a relatively limited amount of flexure, it must be held rigid as it bears a load. Lifting weights requires this rigidity, and the postural muscles of the trunk provide it.
    Back injuries often occur during lifting, and most usually occur when someone is lifting incorrectly. But even when this does occur, the circumstances are markedly different from those in which a hamstring tears. A leg muscle tears during a long angular contraction that involves a significant change in the muscle belly’s length over a long ROM, whereas a back injury occurs over a small intervertebral ROM that may involve little or no movement within the erector belly. Even if the entire lumbar musculature completely relaxes, not much movement will have occurred, certainly not when compared to a sprint stride. This makes it highly unlikely that you will actually rupture a back muscle belly while picking up a sack of groceries, yet these low-force, low-velocity types of activities are precisely where most back injuries happen. In the absence of blunt trauma, true back muscle ruptures are quite rare.
    Most back injuries are, unfortunately, spinal in nature. Think of them as joint injuries, like a knee injury. The intervertebral discs and facet joints are quite susceptible to loaded abnormal intervertebral movement, the kind of movement that back muscle contraction is supposed to prevent. Strong back muscles developed through correct lifting technique are perhaps the best preventative for back injuries, since the habits you form while lifting correctly contribute to spinal safety just as much as the strength it produces does. Knowing this, pay extra attention to form while learning to pull off the floor; it will come in handy. That’s a promise.
     
    Pulling Mechanics
     
    First, let’s make a few general observations about the behavior of the physical system we’re working with here. Moment , or rotating force (sometimes the term torque is used), is the force applied along a rigid bar that makes an object at the end of the bar turn around an axis. Moment is at its maximum when applied at 90 degrees to the thing being rotated. Think about turning a nut with a wrench; your hand placed at a weird angle to the wrench is not strong, and the strongest position is one in which your hand is at a right angle to the wrench. This is why a mechanic always wants to have enough room to get his arm at right angles to his wrench on a stuck bolt.
    Moment also increases with distance away from the thing being turned. A grip on the wrench turns the bolt more easily the farther it is from the bolt. The moment arm is the distance between the bolt and your hand on the wrench, measured at right angles between the bolt and the direction you’re pulling