Why You Should Do Weights Before Cardio
If you can only exercise a couple of days a week, you probably do both lifting and cardio on the same days. While not ideal, you can get the most benefit if you pick up the exercise before running. That’s why.
As youtuber PictureFit explains in this video, it relies heavily on your glycogen , a stored form of glucose that you can rapidly metabolize for energy. Both lifting and cardio exercise require glycogen, and if it’s too low in your muscles, your workouts will suffer. However, your workout will suffer the most because it requires rapid bursts of energy provided by your glycogen stores. On the other hand, cardio’s glycogen burning is slow and steady, which means you can train your body to do it with low glycogen levels, and it can even increase your performance over time.
Another important factor is the body’s production of certain enzymes during exercise. The mTOR enzyme is essential for muscle growth, and your body produces it when you exercise. But AMPK , an enzyme produced by low-intensity exercise such as cardio, suppresses mTOR signaling. So, if you do cardio first, the AMPK your body produces can reduce the amount of mTOR you produce when you exercise later. This means less benefit to you.
Finally, you must consider fatigue. Cardio often leaves residual fatigue in the muscles, which reduces muscle strength production. Your heart will also be stressed, affecting the transfer of energy in the bloodstream. Plus, you may be mentally fatigued from a cardio session. Essentially, lifting weights requires more of your body in a shorter amount of time, so it’s best to do it when you’re fresh and full of energy.
However, do whatever will help you stick to your exercise regimen. If jogging before lifting weights is more in line with your preference, that’s okay. But if you can help, doing resistance exercise will be more beneficial for you in the long run in the first place. Better yet, do them on different days so as not to worry about it. Or, at the very least, do them at different times of the day so your muscles can recover.