This is a very general question but one that is very common.
My very general guidelines for working out is the following:
- 3 weight lifting workouts of 1 hour or less each week
- A minimum of 2 cardio workouts per week of about 30 minutes each at a medium intensity, 3 cardio workouts per week is better
That's it.
Can you make good progress with a 20 minute workout 3 to 4 times per week?
Well, you need to be doing both weight lifting and cardio. If I had to choose only one workout style, that would be weight lifting as this can be modified to also increase cardiovascular conditioning.
But, I will always recommend a combination of weight training workouts and cardiovascular exercise workouts.
So the very general answer to "Is 20 minutes workout enough?" is NO, it is not enough.
Is a 20-minute weight lifting workout enough to build strength and muscle? Yes, it can be if designed properly.
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