Muscles – big versus strong

By John DiTraglia - Contributing Columnist

I did not know that the strength of muscles is not related to their size. But I learned this recently from a Peter Attia MD podcast that interviews Jeremy Loenneke, an egghead with a Ph.D. in exercise physiology and the director of the Kevser Ermin Applied Physiology Laboratory at the University of Mississippi. (1) Professor Loenneke has been studying another counterintuitive thing I did not know about that uses blood flow restriction – that is temporarily cutting down the blood flow to muscles – to make them bigger. This tactic is a new phenomenon among elite athletes especially body building weirdos.

This blood flow restriction idea was first discovered by Yoshiaki Sato using serendipity and self experimentation. He patented this technique as Kaatsu, meaning pressurization in Japanese. How does Kaatsu work? According to physical therapist Nicholas Rolnick, if someone exercises while restricting blood flow, blood and metabolic byproducts become “stuck in the muscle, unable to leave.” Due to the presence of the metabolites, the muscles become ‘fatigued’, forcing the muscle to work harder than it normally would need to, to produce contractions under light loads. The extra effort created together with the blood flow restriction, speeds up the process of building muscle mass, increasing strength. (2)

In this podcast, Peter remarks that one of the most interesting things that comes out of this discussion, “is that blood flow restriction offers a very cool way to study the relationship between muscle size and muscle strength.”

They start with whirlwind tour of muscle anatomy and physiology where it was revealed that muscles naturally want to contract. The ATP energy is actually only burned in the relaxation phase. This is how muscles are useful and when you die the muscles in your body get hard and contracted, that is called rigor mortis. Also muscle strength is controlled two things – by how much nerve signal is sent to the muscle fibers and by how strongly the muscles individually react.

But the interesting stuff is the blood flow restriction story. If you exercise one arm with blood flow restriction by using a band on the arm that squeezes about half the level of your blood pressure and the other without you get the same increases in muscle size and strength with much less exercise duration and effort in the arm with blood flow restriction. But then they noticed that the size grew proportionally more than the strength. Further studies and statistical techniques show that any relationship between the growth and size of a muscle and it’s strength is undetectable. This amazing revelation is not fully understood but different kinds of exercise will differentially affect size and strength. Also blood flow restriction may quicken healing of injuries or after surgery.

So big muscles is a cosmetic issue. Strong muscles is a whole nother thing.

What a miracle it is to be alive and witness to these mysteries of the universe.

1. EXERCISE #179 – Jeremy Loenneke, Ph.D.: The science of blood flow restriction—benefits, uses, and what it teaches us about the relationship between muscle size and strength.


By John DiTraglia

Contributing Columnist

John DiTraglia M.D. is a Pediatrician in Portsmouth. He can be reached by e-mail- or phone-354-6605.

John DiTraglia M.D. is a Pediatrician in Portsmouth. He can be reached by e-mail- or phone-354-6605.