Yes, but you’ll need to balance the two in a way that’s appropriate for your goals.
The principle of specificity states that if you want to improve at a particular skill, you need to train in that skill. Even more simply put: If you want to get strong, you’ve got to strength train. If you want to run a marathon, you need to run. That doesn’t mean you can’t (or shouldn’t) work in other training components, but there should be a focus.
Personally, I want to maintain muscle (both size and strength) so strength training is a primary piece. I also want lungs to go the distance, so cardio is worked in as well. Most times they are separate sessions, other times they are blended. This is where it gets tricky and very individualized.
What I watch for:
If my strength or size is dwindling, then I’ll cut back on the mileage or time on feet per week. If my strength is maintained or improving, then I know I can add more miles or time.
Ways I do it:
I wouldn’t typically add a very long cardio sessions (40-60+ minutes) to a strength workout because it would be too taxing on my body and not allow me to be my strongest on lifts. But shorter (15-20 minutes) interval-style workouts compliment strength training because they add some metabolic conditioning. Those supplemental short cardio sessions would be added to the end of the workout, not at the beginning.
However, there are times where a good challenge is in order: I’ll run massive distance and strength train, but that usually would require a couple days recovery afterwards and cannot be sustained.
Overall, there are lots of caveats or variables to this question.
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