For years, cardio has been the undisputed king of the gym. It’s been credited with everything from shifting fat and boosting heart health to helping us live longer.
But how much of this is actually true? Is cardio really a non-negotiable staple of our fitness regimes?
Personal trainer and author Rubén Ávila, who is CEO of Barcelona-based gym and physiotherapy centre Myofisix, sets out to address misconceptions surrounding the modern definition of cardio, and its true role in our health.
The fitness expert starts by challenging the vague, catch-all way we use the term "cardio" these days. "You could say the word 'cardio' is inspired by Kenneth Cooper's [1969] book, Aerobics, which focused on improving the cardiovascular system through steady-state running. Since then, though, all sorts of activities have been lumped together under that same umbrella."
Ávila explores the common blunders we make when discussing cardio - but are its benefits a "myth"? Well, yes and no. The issue is that we assume what we call "cardio" these days has automatic health benefits that don't always stand up to scrutiny.
"A culture has emerged where doing excessive cardio is seen as essential - almost a badge of honour for anyone wanting to 'be healthy'," he explains. But when you look closely at the supposed benefits of certain activities, or doing too much, "You start to realise that isn't necessarily the case."
The 'cardio' trap & why we've been using the term all wrong
The author believes this myth is partly fuelled by the fitness industry, which has a vested interest in pushing the cardio trend in one form or another. These days, when we mention "cardio," we could be talking about practically anything.
The word "cardio" has become so overused it's become shorthand for any general physical activity, notes personal trainer and fitness author Rubén Ávila
"Cardio has become linked to almost any activity because it lacks a clear definition," Ávila says. Decades ago, it meant heading out for a jog or a cycle at a steady pace; today, everything from dancing and walking to taking the stairs gets lumped in.
© Getty ImagesHowever, Ávila makes a crucial distinction: simply getting your heart rate up doesn't necessarily qualify as a complete workout. From his perspective, the most efficient form of exercise is that which focuses on safety, efficiency and "controlled muscular gains". That is, it's not just about movement for movement's sake - it's about making fitness progress without the aches and injuries.
Does cardio actually help you lose weight? The truth about fat burn
Slimming down or burning fat isn't just down to how much time you spend on the treadmill. "There are so many factors at play," Ávila explains, "from your diet and sleep quality to chronic stress levels and how active you are in your daily life."
When it comes to your actual workouts, he reminds us that training is essentially "controlled wear and tear designed to trigger a growth response in skeletal muscle tissue."
© Getty ImagesThis is the real key to changing your body shape. Since skeletal muscle burns more energy than your brain and liver combined, putting on muscle is the best way to rev up your metabolism. He advises people not to be fooled by the numbers on the scales - you can look slim but still lack any real muscle tone.
Why the heart doesn't 'work out' the way you think it does
Always remember the heart doesn't work in isolation. "The heart is essentially a pump; it adapts its structure and how it functions based on the demands of the skeletal muscles. Its job is to deliver oxygenated blood exactly how the muscle tissue needs it, allowing your body to exert force as efficiently as possible."
The endurance illusion: Why 'general stamina' is a myth
One of the most common claims is that cardio builds "general endurance". But Ávila suggests that endurance is highly specific to the activity you perform, rather than a one-size-fits-all 'general' capacity. "If you run, you'll build up an engine for running," he explains. "If you swim, you’ll become more efficient at swimming; if you hike, you’ll adapt to that specific activity."
"Every action we take with our bodies has the potential to trigger change. The real question is whether cardio is truly the best way to boost performance, or if there are far more effective methods available"
The only truly universal trait, he adds, is strength. "The only intrinsic or general capacity we actually have is the ability to exert force," he says. Improving your strength allows you to perform better across the board.
© Getty ImagesIs your workout actually 'functional'? Beyond the fitness buzzwords
"Functional" is one of those buzzwords that gets thrown around far too often. "For a workout to be functional, it has to respect the natural function of the muscles and joints involved. Put simply: it shouldn't leave you injured." From Ávila’s perspective, running or cycling aren't inherently "more" functional than anything else; they just get you better at running or cycling.
The hidden mental health benefit of movement (that has nothing to do with calories)
When it comes to whether cardio helps with mental health, Ávila is clear: yes, it does. "Any physical activity or sport done for pleasure, for fun or simply as an escape from the daily grind will boost your mood." The real benefit doesn't actually come from the type of exercise you're doing, but rather the emotional connection and enjoyment you get from the activity itself.
© SorapopThe final verdict: Should you ditch the treadmill for good?
For Ávila, the absolute non-negotiable is to try and achieve consistent improvements in your skeletal muscle tissue while keeping the risk of injury to a minimum. This points towards workouts that are controlled, short and intense.
Ultimately, he says, we should probably view cardio as a "nice-to-have" addition - something you do because you genuinely enjoy it or find it rewarding - provided, of course, that it isn't doing your body more harm than good.
