Strong v swole: the surprising truth about building muscle | Fitness
UUntil recently, the conventional wisdom about building muscle was that it worked via a system that might be thought of as “rip and repair” – the idea being that training causes microtears in muscle fibers, which trigger the body’s repair processes, encouraging the muscles to come back bigger and stronger.
This is why many old-school trainers will tell you that there is no gain without pain, and why a lot of bodybuilding advice includes increasingly byzantine ways of pushing your biceps and triceps to the point where you can’t do another rep: the more trauma you can cause, the more “bloated” you can become.
To be clear, this has worked for many weightlifters – especially those aided by over-the-counter performance enhancers, which can help recover from even the most strenuous workouts. But current science suggests there is a better way to think about things.
“The best evidence now suggests that the primary driver of muscle hypertrophy – the technical term for an increase in muscle cell size – is mechanical tension,” says Dr Anne Brady, a professor of kinesiology specializing in muscle quality, physical function and body composition. “Muscle damage certainly contributes, but it’s not the main factor. Usually it’s more of a side effect.”
To explain this a little further: When you lift a heavy enough weight (or perform enough repetitions of a movement to reach near-failure, which you’ll recognize by the fact that your repetitions slow down and seem more “squeaky”), the resulting physical tension stretches the membrane that envelops your muscle cells. From there, specialized sensors called mechanoreceptors detect this stretch and activate what’s called the mTOR pathway, a sort of master regulator that listens to various signals and “decides” whether your body should build new tissue or break down old parts for energy. From there, the mTOR pathway signals the cell to start muscle protein synthesis (MPS) – the process of adding new proteins to muscle fibers to make them thicker and stronger.
“A third factor is metabolic stress, which leads to the ‘burn’ you might feel when lifting,” says Brady. “You can think of this as a mechanical tension amplifier: it’s a form of cellular signaling that creates a favorable environment for muscle growth.” In other words, feeling your muscles start to hurt might mean you’ve pushed them enough to grow, but that might also not be the case—you can get burned by doing enough biceps. curls with a pencil in hand; you won’t grow much because there isn’t enough physical tension to challenge your muscle fibers.
The second key thing to understand about muscle is that you can build a good amount of it without adding a lot of extra strength – or, if you prefer, get a lot stronger without actually getting bigger. “There are two main types of muscle hypertrophy: myofibrillar and sarcoplasmic,” explains Brady. “Myofibrillar hypertrophy is an increase in the number of myofibrils – the bundles of tiny filaments that contract to lift weights – resulting in an increase in force. Sarcoplasmic hypertrophy is an expansion of fluid volume inside the muscle – this results in greater muscle size without additional force.”
This is how Olympic weightlifters can move huge weights without jumping a bodyweight class, and why gymnasts can be stronger in certain movements than bodybuilders who train purely for aesthetics. Science now suggests that one form of hypertrophy rarely occurs without the other, but different types of training can certainly prioritize one style: In a 2019 study, young men who trained for six weeks in a high-volume weightlifting program seemed to see the biggest results from sarcoplasmic hypertrophy: In other words, they got bigger without necessarily getting much stronger. The most effective Growth appears to occur when combining the two types of hypertrophy: using a weight heavy enough to create high tension, but performed with enough repetitions to generate significant metabolic stress.
What does all this mean to you? First, it means that whether something is painful — whether during your workout or in the days afterward — isn’t necessarily a good indicator of how effective it is. “It has been noted that muscles can grow with minimal pain, and on the other hand, there can be a lot of muscle damage with little muscle growth – for example when running downhill,” says Brady. “At the same time, muscle damage can reduce growth if it negatively impacts an individual’s performance during training or the frequency of training.”
It also means you don’t have to worry too much about pushing your limits, or even getting close to them. “I coach mature women and I always tell them not to major in minor subjects,” says Brady: in other words, don’t obsess over trivial details. “During resistance training, I suggest working to failure. This can be accomplished over a wide range of repetitions, as long as the last few repetitions are difficult.”
What trainers call progressive overload – working the muscles more – is still essential, but there are many ways to achieve it: doing more reps in each set, using heavier weights, reducing rest time between sets, etc. Gradually increase the amount you do over weeks or months, and you will become both stronger and probably slightly bigger – but please note that your T-shirts are unlikely to get too big unless you invest in serious pharmaceutical help. Many people try to do this in every gym around the world, and not all of them succeed.
