The plain and simple answer to this question is: there is no answer. There are too many variables that go into how long you should workout to have one definitive answer that holds true for everybody. Some fitness experts will tell you to do 45 minute workouts everyday; no more, no less. This may be the best route to go for some people - but not all people are the same. Therefore, you have to listen to your body and figure out what works best for you with a little trial and error.
Here are some things to consider when trying to figure out the duration of your workout:
- Experience Level- Are you a newbie to the world of fitness, a seasoned muscle head, or somewhere in between? If your body isn’t accustomed to the punishment getting in shape involves, your workouts should probably be short and to-the-point (anywhere from 20-30 minutes) to begin with. Once you start noticing that you are becoming stronger, you can either start bumping up the length and/or intensity of your workouts.
- Fitness Goals- The types of workouts you do should be directly related to your fitness goals. If you're wanting to gain mass, then you will probably be doing a lot of high volume weight training routines which all vary in length according to how long your breaks are and what muscle group you are targeting that day. If you are training to be more athletic, some of your workouts, like plyometric or HIIT routines, will be shorter due to the high level of intensity.
- Intensity- The intensity of your workout is a huge determining factor in how long you should workout. When weight training, some people can go for longer periods of time (1-1.5 hours), especially if they are taking long rests in between sets. In contrast, some CrossFit workouts only last 8 minutes, but they are so intense that you often won't be able to peel yourself off the floor for the rest of the day. The thing to consider here is, did you push your body to the point of extreme fatigue? This is what causes you to change and become stronger. Remember, quality over quantity!
- Personal Time Constraints- Some people have crazy, hectic lives that only leave them a small allotment of time to get a workout in. If you're one of those people that only have a tiny window of time to workout, doing a 20-30 minute workout is way better than doing nothing at all. The good news is, studies have shown that short, but intense workouts can burn the same amount of calories as a longer workout due to something called the after burn effect. This means you'll continue to burn calories at an accelerated rate even after you're done working out if the intensity was high enough.
The key thing to remember is what works for someone else may not necessarily work for you. Listen to your body and happy working out!