In CrossFit, we squat all the time. Whether it’s in the strength work done at the beginning of the class or as part of the metcon, we regularly see back squats, front squats, overhead squats, squat cleans, thrusters and wall balls throughout the week. The squat is so valuable as a training tool because it is A—one of the most functional movements we can perform as humans —and B—it is a pure compound movement, meaning that it activates a high number of joints and muscles. When multiple muscles are worked in a lift, your body secretes higher levels of testosterone and human growth hormone—which are both vital for muscular development. Athletes can have varying goals when it comes to training with the squat to target ‘muscular development’. For some, that muscular development equates to gaining muscle mass (or size). For others, they are primarily concerned with developing muscular strength.
Now, it is important to understand that each goal requires different training methods, with specific regards to the rep and set scheme (and other factors) of the squatting work. The two goals can compliment one another—when you want to get stronger, your muscles can and will grow bigger, and vice versa—but if you’re primary goal is to target one of the two ‘options’, your squat work needs to reflect that.
Squatting for strength
The primary reason an athlete squats for strength is to increase their force production (i.e. the ability of a muscular unit, or combination of muscular units, to apply force). To that end, the name of the game when it comes to increasing strength focuses on the neurological—specifically, your central nervous system (CSN).
The CNS consists of the brain and spinal cord and acts as a control system for the body. The way that the CNS can increase your strength is by raising the number of active motor units in a muscle, and boosting their rate of fire—resulting in a stronger muscle contraction. So to improve your strength, you have to improve the efficiency of the CNS to recruit motor units in a muscle and make them fire. So how is that accomplished?
Through heavy resistance and low rep/sets work. The typical rep/set scheme for developing strength is as follows:
1-5 Reps at 85-100% of your 1-rep-max
Some of the most well-known strength building programs employ a set/rep scheme within this range, including legendary strength coach Bill Starr’s 5×5 program, Jim Wendler’s 5/3/1 program, and the Texas Method. So why are low reps with heavy weight advocated as the best way to build strength?
The answer is a combination of myofibril hypertrophy and neuro-muscular adaptations. Myofibrils are made up of groups of myofilaments, which are the parts of the muscle that contract. Each muscular cell in the human body contains tons of these rod-like units. The heavier the weights you lift, the more muscle fibers are recruited, damaged, and repaired—thus making you stronger.
When we talk about neuro-muscular adaptations, we’re also talking about the CNS. We know that lifting heavy weight engages more muscle fibers to work, but it’s the motor units within your muscles that activate those fibers in the first place. And what system dictates how many motor units are engaged and how rapidly they fire? The CNS. And as we continue to train with heavy weights, the CNS becomes more efficient at recruiting the higher-threshold motor units (type IIb fast-twitch fibers), which makes us stronger as a result. However, lifting heavy weight is very taxing on the CNS, which is why the rep and set schemes need to be kept low.
Squatting for mass
Squatting for strength centers on neuro-muscular adaptations. Squatting for size centers on the physiological—your bones, connective tissues and muscles. Essentially, you want to build your body up through high volume work, which is what will give you the best muscular hypertrophy—the best ‘pump’ if you will.
Now, strength training at heavy loads for low reps targets myofibril hypertrophy. On the other hand, high reps to failure (at a weight that is less than 70% of your one-rep max) induce sarcoplasmic hypertrophy. Sarcoplasmic hypertrophy is when there is an increase in the volume of the non-contractile muscle cell fluid, sarcoplasm. After a workout, your body’s energy sources will have been depleted. Thus, during the recovery period, your body will look to increase the amount of ATP (adenosine triphosphate—which transports chemical energy within cells for metabolism), glycogen and other essential energy sources to prevent depletion in future training periods. As a result, the cross sectional area of the muscle increases, which is what gives you that ‘pump’—but doesn’t necessarily mean you are getting any stronger. Sarcoplasmic hypertrophy is commonly attributed to high-repetition, moderate weight training—which is typical of bodybuilders. This explains why a bodybuilder might have more muscle mass than a powerlifter, but won’t be able to out-lift them. This type of training is known as fatigue training, as it rapidly uses much of the stored energy (such as ATP) in your muscles. Typically athletes will base their rep/set scheme off the following numbers when looking to increase muscular mass:
Popular mass-building programs that incorporate reps/sets in this range include the Dan John bulking program, German Volume training and 20-rep squats (OK, that’s slightly over the rep range, but they are regularly employed by Rich Froning in his classes at CrossFit Mayhem Freedom, so you know they are valuable). So, what are the benefits of a higher set/rep scheme when it comes to building muscular mass?
I have already explained how high volume, low weight work targets sarcoplasmic hypertrophy, which is important for muscle mass growth. In addition, several studies have shown that high volume, multiple set programs are more effective at increasing the body’s production of testosterone and HGH (hormones that are important for building muscle size). Another important element to consider is muscle time under tension. In order to build maximum muscle, your body not only needs to experience tension through a full range of motion, but it needs to experience significant time under tension. Your muscles won’t get any bigger or if you only perform a few maximal contractions once or twice every couple of weeks. You need to provide them with a constant stimulus in order for them to grow larger, and this is why a high rep/set scheme is employed.
Photo courtesy of Janeen Chang Photography