Why your HIIT workouts might not be hitting

We've all been there. You're fifteen minutes into an Ultimate Shred HIIT class and you're watching the clock, wondering when the burpees will end. Your vision is blurring, your heart's hammering against your ribs and the trainer is screaming over the blaring music about “earning that summer body”. You want to quit, but remember what the fitness industry has always preached: no pain, no gain… right? 

We're conditioned to believe that the only way to peak fitness is to suffer through a workout, but after months of this soul-crushing effort, many of us end up hitting the wall. Energy crashes, the scale plateaus, muscles feel weaker, cardio becomes a chore and we're left wondering why our dedication isn't paying off. 

If you feel like you're working harder than ever but the results aren't there, the problem might not be your lack of grit. It could be your body doing exactly what it should when it's under stress: protect you. 

The ‘no pain, no gain’ myth debunked 

When we push ourselves to the brink seven days a week, our brains don't see a fitness goal. It sees a survival situation. It quite literally thinks we're being chased by a predator or enduring a famine, so it slows down our metabolism and holds onto every ounce of energy it can find. That's why the ‘no pain, no gain’ mentality can actually become your biggest roadblock. 

According to research by Monash University, your body responds to extreme, chronic physical stress by slowing its metabolism and diverting energy away from non-essential functions, such as tissue repair. This persistent survival mode keeps cortisol levels high, signalling your body to hold onto fat stores and even leading to adaptive thermogenesis (where your body lowers its metabolic rate to conserve energy).  

To put it simply, a constant state of suffering convinces your body that you're unsafe, causing it to stubbornly protect its current state despite how hard you're trying to shift it. 

In some ways, this is amazing. Our bodies are always trying to protect us, but when you're slugging away at the gym, it can be incredibly frustrating. 

Exercise and your total stress load 

If you feel those high-intensity workouts are failing you, it could be time to factor in your total stress load. Your body doesn't distinguish between the stress of a deadline, a lack of sleep or a burpee - all of these can trigger cortisol release. 

The reality is that most of us are already living in a state of chronic micro-stress. Our modern lifestyles mean we're constantly on: endless notifications, multitasking and the mental load of the 24/7 digital world. When you layer a gruelling HIIT session on top of all that, you're adding fuel to the fire. 

For some women, this stress bucket is even more sensitive. High-intensity exercise is a powerful stimulus for the sympathetic nervous system and if the body doesn't feel safe, it begins to prioritise survival over metabolic efficiency.  

If you spend eight hours in a high-pressure office and then head straight to a high-intensity boot camp, you're effectively keeping your body in a state of fight or flight for sixteen hours a day. No wonder you’re suffering. 

Instead of fitness gains, you're actually inducing inflammation, poor sleep and stubborn weight gain. 

The solution: reframe your workout routine 

It can be helpful to remove morality from your exercise routine. It has nothing to do with your motivation. Your gym routine does not reflect your willpower or your worth. You've clearly proven you have the grit to endure hard things. It's time to use that grit to loosen your grip. 

By shifting from a ‘more is better’ mindset to a ‘quality over quantity approach’, you give your body permission to recover. Most experts recommend two to three high-intensity sessions per week as the sweet spot for fitness gains without the hormonal burnout.  

The rest of your week is about maintaining momentum with strength training and draining your stress bucket through low and slow movement, like a long walk.  

A balanced weekly rhythm 

2 days of high-quality intensity: Short, sharp sessions where you give it your best. Think 20 minutes of intervals on the treadmill or spin bike, or a fast-paced circuit. 

2–3 days of strength: Around 45 minutes of controlled movements to build muscle to support your metabolism without sending your cortisol into orbit. 

Daily stress drainage: At least 30 minutes of low and slow movement like a morning walk, a gentle swim or even some light gardening. Yes, hobbies can count for daily movement too. 

1–2 days of real rest: Give your nervous system a total break—you deserve it. Rest, catch up on your favourite show, recover. 

When you stop trying to suffer your way to wellness, your body often feels safe enough to stop protecting its current state and starts allowing you to feel good and enjoy the fruits of your labour. 

Please note: The information throughout this article serves as broad information and should not replace any advice you have been given by your medical practitioner.