We mused on squats yesterday. Inevitably when we broach the subject, Smith machines weasel their way into the conversation. They’re not without their virtues, but be mindful; they’re slippery suckers.
As a moppet of 13, I attended a fitness center in the San Fernando Valley called “Nautilus.” The place was jam packed with state of the art (for the 1989) equipment. Keiser air pressure machines were all the rage and crowded the space, but I had my eye on learning how to bench press. It seemed like the macho activity and I was anxious to chime in on the “how much can you bench?” conversation. Being particularly wet behind the ears, I was comfortable when my establishment didn’t have a traditional bench but was equipped with a Smith machine.
A Smith machine is a barbell on rails. Some folks believe that performance is safer if you’re lifting without a spotter, since you can’t drop the barbell if you’ve added too much weight to support it. This claim is not without merit, but it’s also not without risk. Plenty of people overload the bar, pushing past their point of failure because they feel safe. This isn’t inherently bad. However injuries can and do happen with Smith machines, likely driven in part because of a lack of awareness.
But, you may think, now that you’re aware of the risk, surely there’s no downside to using the Smith machine. Back to my tale. Over the months, I incrementally added weight to the bar while ignoring the fact that I was receiving assistance. I was proud when I was able to push 150 pounds. I wasn’t shy about sharing the information with my boys while riding the RTD (Los Angeles public transportation). One of them called me out to prove it at school where there was indeed a traditional bench. Needless to say, that didn’t end well. My body wasn’t equipped to balance the weight on my own and you can imagine the fallout. Failure.
Smith machines, on critical exercises like the squat and bench, assist not only in moving the weight, but they also balance for us and force us into a cookie cutter movement, moving only in one direction (vertically). Our bodies don’t move in only one plane in day to day life. Our stabilizer muscles do not engage and unnatural stresses are placed on our backs, knees, hips and core muscles. In particular, the Smith machine may pose risks to the patellar ligaments and ACLs.
It’s not just the lack of engagement of the stabilizing muscles. I failed at the benching the same amount with free weights because the Smith machine practice literally required my body to do less. From a study in the Journal of Strength and Conditioning Research:
The purpose of this experiment was to determine whether free weight or Smith machine squats were optimal for activating the prime movers of the legs and the stabilizers of the legs and the trunk. Six healthy participants performed 1 set of 8 repetitions (using a weight they could lift 8 times, i.e., 8RM, or 8 repetition maximum) for each of the free weight squat and Smith machine squat in a randomized order with a minimum of 3 days between sessions, while electromyographic (EMG) activity of the tibialis anterior, gastrocnemius, vastus medialis, vastus lateralis, biceps femoris, lumbar erector spinae, and rectus abdominus were simultaneously measured…the EMG averaged over all muscles during the free weight squat was 43% higher when compared to the Smith machine squat (p < 0.05).
The Smith machine may help you boast about how much weight you’re pushing (while leaving out critical information). If your desire is to build strength, keep your body healthy and perform the movements of daily life better, get under a bar without rails.