“What are your thoughts on strength training twice a day?? I’ve only done it once a day but I may be in a situation where I need/want to do it twice a day?? What would the approach be (Same muscle group or different muscle group). Thank you in advance.”
It can work for sure. It depends on what your goals are, what your schedule is, and various other factors.
I don’t think in terms of muscle groups for my training. Instead, I think in terms of movements.
It may not seem like a huge distinction but it’s important to break free from the “cult of muscle”. If you’re not a competing bodybuilder than you don’t need to be thinking about your muscles that much that your training is divided up by them. There are other important tissues besides muscles for one.
And secondly, you’re not just a bag of different muscles, but a human body that moves. Most people want to look good, move well and pain free. Therefore, the focus on the muscles is not the best way to get there.
Sorry, off on a rant there, back to the question…
It all depends on HOW you do the training. Same movements (or muscle groups if you must) can be trained every single day…or once every other week depending on all that.
For instance, most of my training right now is actually doing sets spread throughout the day. This has been popularly called Greasing the Groove.
It works. But it isn’t the only method that works.
Most important to more frequent training is that the severity of it can’t be too high. Severity and frequency is the route to burnout and/or injury.
Note that severity is not the same as volume or intensity (% of 1RM). You can do frequency with volume OR intensity. (The “or” is important because volume AND intensity equals severity.)
As for the approach, this totally depends on your goals.
If it is because of a scheduling conflict, you could simply take what you were doing in a normal once per day workout and chop it in half to do it twice per day.
Or the two different workouts could be completely focused on different things. One could be strength training while the other was endurance, or flexibility, or something else.
The more important factors than once or twice per day is that you have the stimulus, aka the training, and then appropriate recovery time for it.
If you have those you can make progress. Simple as that.
You can find much more on these concepts inside of The Master Keys to Strength and Fitness. In fact, it is not understanding this foundational concepts that lead to questions such as this.