Question: Why are compound exercises better than isolation exercises? I ask, because you often say beginners should rarely do isolation movements, if at all. I want to do preacher curls and triceps pushdowns to build bigger arms. – Tim (Kansas)
Answer: Hey Tim, thanks for the question. As a beginner, your time can be spent much more productively by frequently performing a few fundamental weight lifting exercises.
This way, you can familiarize your body by learning the of movements that will build a foundation of strength and size.
High frequency training, such as a 3 day per week full body workout routine, is important because at this early stage you need as much repetition as possible to “solidify” the movement and make it second nature.
Think of the idiom, “practice makes perfect.” So if practice makes perfect, then it makes sense that practicing more often will improve your exercise technique as fast as possible…
…But one might ask, “But how can you recover if you’re doing the same exercises and working the same muscles 3 times per week?” Good question. There’s two parts to the answer:
First, a well structured beginner full body routine (e.g. MYx8, Rippetoe’s Starting Strength) doesn’t have so much volume (sets x reps per workout) that it over-stresses the muscles to the point of interfering with proper recovery.
Second, beginners do not have the physical conditioning and efficient technique required to lift weights that are too heavy. That is, until your body can perform an exercise like it’s second nature, you are physically unable to lift loads that tax your body and central nervous to the point that you need more recovery time per muscle/exercise.
When you’re relatively new to weight lifting, training with a limited number of exercises provides the “focus” needed for the body to become proficient with technique. You create a better mind-muscle connection (which includes muscle awareness or “proprioception”) and you become stronger through neural adaptation. Again, this is done in the shortest amount of time by focusing on a few major lifts.
If novice trainers instead choose to start a routine filled with a bunch of isolation exercises for the arms and other minor body parts, it has the effect of “watering down” their focus. Thus, they progress slower; achieving less technique proficiency and the basic strength needed to maximally leverage long-term muscle building.
It’s like multitasking in daily life: It may seem like you’re getting more done, but it’s been proven that you’re significantly more productive by focusing on one task at a time.
However, in terms of weight lifters that are beyond “newbie stage” in experience, I believe that isolation movements are required for achieving a goal such as adding mass to a specific body part.
That was probably a longer answer than you were hoping for, but now you should have a thorough understanding of why compound exercises are better than isolation exercises, especially for beginners.