An interesting question on the X-Rep Facebook page: Does 4X work for all body types?
For those unfamiliar, 4X is taking a weight with which you can get 15 reps, but you only do 10; rest 30 seconds, then do it again. And so on until you complete four sets. You go all out on set 4, and if you get 10 reps, you add weight to that exercise at your next workout.
Lots of trainees think that 4X is endurance training due to the short rests. That would mean it produces more growth in the sarcoplasm, the energy fluid in the muscle fibers, than growth in the myofibrils, the force-generating strands in the fibers. That’s not a bad thing because researchers are beginning to find that the sarcoplasm has the most potential for growth compared to the myofibrils.
Nevertheless, 4X actually provides a balance stimulus—it trains both “sides” of the muscle fiber. That’s why density training is so effective at building mass. It’s why legendary trainer Vince Gironda (pictured at left) was such a proponent of this style—because it produces rapid muscle growth on both sides—the myofibrils and sarcoplasm. The 4X mass-building method works for all body types.
There are people who are myofibrillar dominant, such as Mike Mentzer. They are very strong at a young age. He could squat 600 pounds at age 16, which shows the force-generating power he had via excessive myofibrillar activation and population in his muscles.
But Menzter made tremendous strides in mass when he began pre-exhaustion training, which is primarily a sarcoplasmic-expansion tactic. You use a continuous-tension isolation exercise first followed immediately by a multijoint, or compound, move for that same body part. For example, pec deck flyes followed immediately by bench presses. While that style does train the myofibrils somewhat, it emphasizes sarcoplasmic expansion—and Mentzer’s mass flourished with pre-ex.
Mike was a mesomorph–athletic and muscular. Most mesomorphs appear to be myofibrillar dominant. But that just means they can get excess size by focusing on the sarcoplasm. Their myofibrils go along for the ride and grow anyway—like a strong body part—no specific emphasis necessary.
Skinny trainees, called hardgainers, are ectomorphs, and they usually have less strength potential due to lacking myofibrils. With 4X training they get both types of stimulation—however, the sarcoplasm is what gives them the most muscle size. That’s the reason heavy, low-rep, straight-set routines rarely do much for hardgainers’ muscle size. It takes methods like drop sets, 4X and supersets to jolt growth via sarcoplasmic expansion. That’s the best way for hardgainers to get the “bodybuilder look.” (A good example is Vince Gironda pictured above.)
What about endomorphs—the more heavy-set type? The 4X method ignites tremendous muscle burn on the latter sets, and that’s a known trigger for growth hormone. GH is a potent fat burner, so they will get both leaner and more muscular with 4X.
There are 4X hybrid methods other than just the standard sequence tactic described above, and those may be geared to certain body types. I’ll have more on those in future blogs. Just realize that whatever your body type, 4X can do great things for your muscle size.
Stay tuned, train smart and be Built for Life.