One of the major hurdles faced by Beachbody when creating Body Beast was trying to create a program that could elicit measurable hypertrophy (muscle size) gains with fairly basic home workout equipment. Many people, including myself, was skeptical of the idea of being able to build mass without some of the heavy weights and equipment used in your standard gym.
Although, you may need a decent selection of weight in order to maximize your benefits from Body Beast - staying within specific rep ranges, it turns out, you may not need to train with as heavy weight as you may think.
When working with untrained beginners, personal trainers may be able to produce hypertrophy using lighter loads (15RM+ or <65% of 1RM). Such hypertrophy may be similar or only slightly inferior to that achievable using heavier loads and this may allow for greater variety and an initially less-challenging task for the client.
Here are a few points to be taken into consideration, however:
- All of these studies used untrained individuals. Virtually any form of resistance training could probably elicit some sort of muscle size increase in untrained individuals for a number of reasons, including water retention, increased glycogen storage, and swelling due to new stimulus. Virtually all "beginners" achieve some sort of muscular hypertrophy when they first begin a resistance training program (regardless of rep range or resistance used).
- Although a home workout program like Body Beast can result in muscle hypertrophy, it is just that, a hypertrophy program and oftentimes I see individuals confusing muscle size increase with strength gains. Sure, one may increase their overall strength due to the stimulus being used, however, Body Beast is not the optimal program in order to develop overall strength. (Refer to the following diagram)
Traditional strength training uses compound lifts (bench press, squat, deadlift, overhead press, barbell row, etc.), typically in the 1-5 rep range with longer periods of rest (2-5 minutes) to maximize the amount of force that you can generate every set.
Resistance training at any rep range will more than likely elicit improvements, especially with progressive overload (increasing resistance every or every other workout). Don't confuse the fact that increasing your weight for a 8-rep set of dumbbell squats as a tremendous increase in strength. Your muscles are getting better at squatting more weight for that rep range, but that doesn't necessarily mean that your 1 rep maximum (1RM) for the squat has improved by any significant means.
Traditional strength training has been thought to be better at producing "denser" muscles by increasing the size and strength of the myofibrils whereas higher rep resistance training (Body Beast) increases the size or volume of the sarcoplasm.
Well, it’s no secret that when you lift heavy stuff and eat enough food, your muscles will get bigger. In fitness circles it is commonly said that gross muscle hypertrophy can occur in one of two ways: Either through increases in the volume of myofibrils inside the muscles, termed myofibriller hypertrophy, or through expansion of the “other stuff” (usually the fluid) in the muscle, termed sarcoplasmic hypertrophy. In normal cells, the fluid inside the cells is called cytoplasm, and in muscle fibers, the corresponding volume is called sarcoplasm (“sarco” meaning flesh). Supposedly, heavy, strength-oriented training (big weights, few reps, long breaks) will grow “denser”, myofibrillar hypertrophy, whereas lighter, pump oriented training will induce “puffy” (often claimed “nonfunctional”) sarcoplasmic hypertrophy. “Non-functional”, because this latter type should not be associated with increases in strength, as the capacity to produce force is derived from the contractile, myofibrillar protein. The really funky part about this idea is that it is the purest broscience and it lacks both solid evidence as well as a sound biological rationale and somehow it has managed to creep into the scientific literature anyway.
I think that the research tells us that various rep ranges of training can generate a wide range of improvements to the muscle. We know that 12+ repetitions improve muscular endurance properties as well as increase muscular size of type-1 (aerobic) muscle fibers. We know that 6-12 reps is *typically* ideal for muscular hypertrophy, with the 6-8 rep range often considered as "functional hypertrophy" due to the added strength benefits. Lastly, we know that traditional strength training in the 1-5 rep range is best for improving the overall force the muscles can generate.
Ultimately, there seems to evidence that points to hypertrophy at all rep ranges. 12+ reps can increase the size of type-1 muscle fibers. 6-12 and 1-5 reps can increase the size of type-2 muscle fibers. Beyond that, you simply need to consume enough calories (surplus to what you burn on a daily basis) to increase muscular size/volume.
In my opinion, one of the most effective things about Body Beast is that the program does target both the 6-12 rep range as well as the 12+ rep range, targeting hypertrophy of both the type-1 and type-2 fibers.
No individual should stick to any program or training style for too long because their progress will eventually plateau. I always recommend an individual transition to another program that will help them reach their overall goals.
Hypertrophy training can be especially important, beyond aesthetics, for athletes or individuals who wish to gain weight for a specific sport or event. Football players, for example, could benefit from hypertrophy training early on in their training macrocycle, gaining weight and muscular size first, prior to engaging in traditional strength training to therefore make their larger muscles stronger. Big muscles don't necessarily mean they are stronger, but they can certainly have a higher affinity for strength gains.
I would personally like to see some studies conducted on the long-term effects of various forms of hypertrophy training. Is it possible to create denser, and therefore more resilient muscle fibers by doing strength training, therefore creating growth for longer periods of time? Will sarcoplasmic hypertrophy "fade away" quicker if resistance training is stopped due to insufficient stimulus increasing the volume of the sarcoplasm?