When you finish a CrossFit workout do you feel completely wiped out? Do you work as hard and as fast as you possibly can? If you do, you are creating good stress on your body.
Stress creates adaptation. It usually goes one of two ways.
With minimal effort, you do not put enough stress on your body. You will adapt to be slower and weaker. Basically, if you don’t use it, you lose it. If you stop challenging yourself, you will become stagnant in your progress and possibly even backtrack.
With maximal effort, you will stress your body enough to make it adapt into a stronger, faster machine. When you move faster, lift heavier, and rest less during a workout, your body will adapt, making it easier the next time you workout.
This is why I call it good stress.
There are a few ways your muscles can adapt.
Neuromuscular adaptations happen the fastest compared to other adaptations. Your body can recruit more motor units for a muscle contraction. This is called motor unit recruitment. The more motor neurons that are recruited, the stronger the muscle contraction will be (you will be able to lift more weight).
Hypertrophy is another way your body can adapt. This can happen in a couple of ways. Your muscle fibers can get bigger, or your muscles can increase the amount of glycogen (energy) they store.
Your body can also get more efficient at buffering lactic acid. When you get to the part of your workout when your muscles start to burn, you are feeling that moment when your body is reaching lactate threshold. This means you’re producing more lactic acid than your body can get rid of, and then your muscles cannot contract. Over time your body will adapt by buffering it out more efficiently so you can workout for longer at a higher intensity. Just be aware that training at your lactate threshold will require mental toughness because it is not comfortable. Some adaptations do not come so easily!
Blood capillaries will become more efficient to supply muscles with oxygenated blood. Your muscles can also develop more mitochondria to produce more energy for your muscles. Even your fiber types can change depending on what type of training you do (fast twitch or slow twitch).
There are also other adaptations that occur such as cardiovascular, bone, respiratory, and hormonal adaptions.
You need to create stress on your body by moving faster, lifting heavier, etc. Then your body will make adjustments and adaptations to get better. If you struggle to lift it, your muscles will get stronger. If your legs cannot sprint anymore, your will become more efficient at buffering out the lactic acid.
Once your body adapts to the stress, you have to increase the stress. This means you have to work faster, lift heavier, etc once your body gets used to it.
There is always room for improvement!