This will be a three-part strength series. This first part will cover the general basics of how we get stronger neurologically, and how and when CrossFitters should begin to add extra strength work in. The second installment will cover how physiological strength gains, different rep schemes and how time under tension affect strength gains, and the final installment will discuss how long to rest between sets, and different types of training patterns. Note–this is primarily focused on building barbell strength, with the absolute strength movements. Speed strength, as in olympic lifting, is a more complicated topic for a later series.
Everyone remembers “newb gains.” Those magical first few months of training, where every time we went to the gym, we managed a new PR or learned a new movement. As we discussed in our skill acquisition article, these improvements are due to our brains’ becoming more efficient in the movement patterns. While these improvements do need time in between sessions in order to allow for automation of simple aspects of the movement, the rate of improvement from neurological strength changes will happen on the scale of days and weeks, as opposed to the weeks to months needed to see changes in our amount of muscle. Today we’re going to delve into the specifics of what happens to our bodies during strength training, and why new CrossFitters should focus on just doing CrossFit before they add extra strength training into their regimens.
Strength is essentially a measure of our ability to overcome gravity. But what is happening in our bodies as we lift objects? Our brains tell our muscles to contract, and the force of that contraction is one measure of how strong our muscles are. However, in CrossFit, we don’t really care what the measurement of our contractile potential is–we care how much weight we can lift, or how many pullups we can do, or how fast we can push that 500 pound sled. In CrossFit, we define strength as the productive application of force. However, it’s still helpful to understand how our brains interact with our muscles, because it’s that connection that helps us improve our productive strength. Our muscles have motor neurons that are connected to our brains. When we think “perform a bicep curl” our brains send a signal to the motor neurons in our biceps, which cause contraction, and picks the weight up. However, when we’ve never lifted, there aren’t that many motor neurons in our biceps–and we aren’t all that efficient at using them! While a bicep curl is quite a simple movement, try and remember the first squat that you ever did. Most likely, you had a hard time keeping your legs from shaking, your hips from moving side to side, and getting to depth seemed nigh impossible. While there are several reasons for this, one reason is because our brains’ timing is off as we learn new movements. When we measure new lifters’ muscle contraction, we actually see that different motor units (motor neurons+muscle fibers) contract at different times, in opposition of each other.1 Essentially, your muscles are playing tug of war with each other! As we perform more squats, our brains get more efficient at using our muscles, and we lose the baby-giraffe-learning-to-walk feeling.
However, it’s not just contracting at the right time that our brains learn to do better. We also have protective mechanisms in our brains that prevent us from using too much force when we contract muscles–this is called neural inhibition. If you’ve ever heard urban legends about mothers lifting cars off of children, it’s been hypothesized that during times of extreme stress, we actually turn off neural inhibition in order to recruit as much power as possible. While we don’t want to completely shut off the protective mechanisms of our brain, we do need to teach our brains that producing force through a new range of motion is safe. Luckily, sustained strength training does just that! Untrained lifters placed on a resistance strength program showed reductions from 17-100% in neural inhibition in various muscle groups through the upper quad. (Note that we didn’t see a complete elimination of neural inhibition–just that some parts of the quad had completely fired, while other muscle fibers still demonstrated lower levels of inhibition.)2 This is why weights that feel heavy one day can feel much lighter a few trainings sessions later.
Now–what does this mean for new CrossFitters? First–it means that you should expect to get better each training session! This is NOT an excuse to throw form out the window and put more weight on the barbell just because you lifted a certain weight last training session. However, in order to maximize strength gains in the beginning of your training life, you should regularly lift heavier weights than you have previously. This will continue to challenge your central nervous system to become more efficient. It will also give you the confidence that comes from continued success. Finally, since the main limiter of our progress at the beginning is neurological efficiency, it actually takes some time before we are able to lift weights heavy enough to challenge our muscles enough to stimulate muscle growth. Therefore, pushing yourself to lift heavier weights (with good form) will lead to long term progress as well.
Secondly, it means that new CrossFitters shouldn’t add standalone strength programs into their programming. While we haven’t discussed recovery yet, here’s a sneak peak: we only get physically stronger from what we can recover from. While sleep, nutrition, and other factors impact recovery, one big factor for new CrossFitters is the total volume of work that they do. Your body is getting used to working out in a new way, and you’re absolutely going to be sore and tired. Adding another hour of lifting into your regimen is going to negatively affect your ability to recover. Moreover, because time and exposure to these new movements drive your improvements at the beginning, the weights used in CrossFit workouts and warm ups will be enough to make you stronger! Finally, there’s the psychological piece–when we start CrossFit, everything is new and fun and enticing. However, doing too much too soon is a good way to burn yourself out. At the beginning, come in and work hard during class. Get to know everyone, have fun, and don’t overwhelm yourself. Once you’ve gone a month or two without PRing a lift, then it’s time to start thinking about adding in some extra strength work. Remember–long term progress is the path to true strength! Trying to get everything done in 6 months is a good way to get overwhelmed and stop coming to the gym–which will just throw all of your newfound gains out the window.