By Brasen Tham and Jasper Lim (Y12)
What Science Really Says About Knuckles, Stretching, and Your Brain
Medical myths are surprisingly resilient. They get passed down from parents, repeated by coaches, and reinforced by how intuitively true they feel. Once something sounds right, it’s hard to let go – even when decades of research quietly say otherwise.
Here are three classic health myths that refuse to die, and what science actually tells us.
Myth #1: Cracking Your Knuckles Causes Arthritis
The common belief is that if you crack your knuckles too often, you’ll pay for it later with stiff, painful joints.
So where did this myth come from?
Knuckle cracking is loud, sudden, and honestly a bit unsettling to watch. For generations, parents and teachers warned kids to stop before they “ruined their hands.” Arthritis also tends to appear later in life, which makes it easy to blame earlier habits for its cause.
What is really happening in your joints that creates a cracking sound isn’t bones grinding together. Instead, it’s caused by gas bubbles rapidly forming and collapsing in the synovial fluid, which lubricates your joints in a process called tribonucleation.
Multiple studies, including long-term observations, have found no link between knuckle cracking and arthritis. Nevertheless, it may temporarily reduce grip strength and hand swelling in heavy habitual crackers, but this isn’t permanent or dangerous. While there are theories that might support the idea that cracking your knuckles does cause arthritis, it has not been firmly backed up with evidence. Arthritis risk is driven by age, genetics, joint injury, and inflammation, not popping sounds.
Bottom line: Annoying? Maybe. Dangerous? No.
Myth #2: You must stretch before exercise to prevent injury
According to some sources, there has been an international consensus that stretching does not reduce the risk of injury. Truth is, there’s been much change in the world of stretching, and the myths that have been passed down with time through the gym don’t hold up as well.
A factor that is in play is the type of stretching that you’ll be doing. In fact, there are two types of stretching – static and dynamic. Static means stretching and holding a joint for a longer period of time, and dynamic is moving while you’re stretching. Dynamic stretching can be repeating the actions that you’ll carry out in your exercise. Each has its pros and cons; while static is good for an increase in the range of motion and feeling at ease, you don’t warm up the muscles. You might even cause some injury if you hold a pose for too long. Dynamic stretching can increase power, blood flow, and coordination, but it might not entirely warm you up for high-intensity activities.
Just because you stretch doesn’t mean that the risk for injury goes away entirely. Proper equipment and general fatigue, as examples, also play their role. Seek having some stretching for the benefits, and not for the struggles; if there’s an activity that helps with areas that are helpful for your activity, then good! But if it makes you feel worse after, consider finding a different type of stretch or not needing to stretch at all.
Myth #3: People are either left-brained or right-brained
Modern brain imaging tells a different story. A large study analyzing resting-state MRI data found no evidence that individuals preferentially use one hemisphere more than the other overall (Nielsen et al., 2013). Nearly all complex cognitive tasks, such as creativity, reasoning, emotional processing, and problem-solving, require networks that span both hemispheres, communicating continuously through the corpus callosum. The brain is less like a divided office with separate departments and more like a highly integrated team project.
The appeal of the left-brain/right-brain myth lies in its simplicity. It offers identity. It explains strengths and weaknesses in a single tidy sentence. But neuroscience rarely cooperates with tidy narratives. Human cognition emerges from distributed networks, not hemispheric personalities.
What these myths share is not malicious intent, but intuitive plausibility. Knuckles pop, so they must be wearing out. Muscles feel tight, so they need stretching before use. One hemisphere controls certain tasks, so perhaps it controls us. Each myth contains a small kernel of truth that grows into an oversimplified conclusion.