Almost every article or social media post about barre and Pilates mentions the “burn” that people experience while doing the exercises. Some consider it as a sign that the workout is going well, but others are still unsure about what it is exactly. Let’s dissect the science behind the burn, and find out why it’s an essential and unique component of barre and Pilates exercises.
The science behind the burn explained
There are two types of muscle fibers: slow-twitch (Type I) and fast-twitch (Type II). Slow-twitch muscles take longer to activate than fast-twitch muscles, but aren't as easily fatigued as the latter. This is why they're used for long-endurance feats like marathons. Fast-twitch muscles, meanwhile, work differently: they are easy to set in motion, but also get tired quickly. Hence, they are used for powerful but short bursts of actions, like sprinting.
Both barre and Pilates target slow-twitch muscles only, and engage them in repetitive but relatively low-impact movements to the point of exhaustion (but not beyond what the body can handle). Slow-twitch muscles use oxygen for energy, and during a barre or Pilates class, oxygen supply may get depleted because a person’s breathing technique doesn’t allow enough oxygen into the bloodstream. When oxygen supply becomes limited, the body taps into another source of energy: anaerobic glycolysis, or the process of turning glucose (sugar) into lactate. The body then converts lactate to energy without the use of oxygen.
But while anaerobic glycolysis keeps the body energized, it also has a downside. It gives off hydrogen ions (H+) as byproducts, which permeate the muscle cell and turn them acidic. This increased H+ acidity in the muscles is what people perceive as a burning sensation, hence the term “burn.”
In short, when you experience the burn, it’s not muscles ripping or tearing; it’s just hydrogen ions.
Why do we only experience the burn in barre and Pilates classes and not in High Intensity Interval Training (HIIT) or weightlifting?
Neither HIIT nor weightlifting practitioners experience the intense burn Pilates and barre practitioners do, because the former kinds of exercises tap into fast-twitch (Type II) muscles instead of slow-twitch muscles. Since they activate different kinds of muscles, they also require movements that are different from that of Pilates or barre. They do quick, powerful movements instead of repeated isolated muscle motions. And because these actions only last for a short time, muscles in the body don’t have time to accumulate enough H+ before it turns the body acidic.
Moreover, they have ample time to catch their breath between each set, enabling them to use oxygen instead of lactate for energy. If a person taking barre or Pilates were to control their breathing better so that they have a free flow of oxygen in their system, then the burn will most likely lessen. (It will not completely go away, however, because the very nature of barre and Pilates requires the muscles to go through anaerobic glycolysis.)
In other words, the burn is unique to barre and Pilates, because these exercises test your endurance by making your body use its reserve energy.
To a new barre or Pilates student, the burn might seem like a discomfort, but to those who have been doing barre or Pilates for a long time, the burn is an indication that they did well in the workout. It’s one of the most fulfilling feelings in the world.
Ready to experience the burn? Book a barre or a Pilates with C2 body today.