Exercise can make you feel happy; any 11-year-old who’s had a quick biology lesson on endorphins can tell you that. The so-called “runner’s high” has the potential to pick us up and lift us out of a low mood – or even diminish pain – before our bodies stabilise and return to our baseline from around 30 minutes to a couple of hours after we cross the finish line.

For a long time I’ve used exercise like pulling the eject cord on my brain: Anxious? Go on a stop-start 5k. Ruminating on destructive thoughts? Book a gym class. Unexplained edginess? Walk until your legs get sore – but the euphoria would always wear off, thumping me straight back down to where I started. Until I realised I’d been doing it all wrong.

Generally, I’d been busying myself with anaerobic exercise: high intensity bursts of movement like sprinting, high resistance reformer pilates classes, and HIIT workouts that relied on energy already stored in my muscles and offered me a short-term boost in mood – but, ultimately, still left my nervous system in fight or flight mode for most of every day.

Yet, this month, a new study published in the Journal of Sport and Health Science found that 150 minutes of moderate to vigorous aerobic exercise a week can actually cause a long-term reduction in the stress hormone cortisol – rather than just a temporary endorphin high. This rigorous cardio could provoke long-term changes to baseline stress levels and reduce the background noise of anxious thoughts.

In the first-of-its-kind clinical trial, researchers randomly split 130 adults between the ages of 26 and 58 into two groups. The first group did vigorous aerobic exercise for 150 minutes each week for a year, while those in the other group were handed health information and told to maintain their usual workout routine. At the end of the 12 months, the adults in the aerobics group showed a clear drop in cortisol, high levels of which can cause side effects including anxiety, mood swings, irritability, poor sleep, digestive issues like bloating, gut imbalances and weight gain.

Unsurprisingly after reading these results, I wanted to be part of the first group after years parked in the second; It was clear from the study that I hadn’t been moving fast or consistently enough to shirk the anxious thoughts often racing through my mind.

I needed something that was going to make me sweat, with cardio intense enough that it would keep my heart rate up, resulting in me struggling to speak, so that I was using energy from my respiratory system instead of the reliable reserves stored in my muscles.

For this, activities like skipping at speed, fast jogging, rowing or rapid cycling work well. But to achieve the level of consistency dictated in the study (the equivalent of two and a half hours every week), I knew I needed something that I would actually enjoy in order to keep it up as part of a long-term lifestyle change instead of a fad.

For all its controversy, I’m still a pilates girl at heart. So, I looked into options that could optimise my existing routine and make it compatible with my aerobic goals. During this research, I came across Paola’s Body Barre (PBB), a studio in southwest London, whose founder, Paola di Lanzo, has combined ballet barre, pilates, yoga, weights and cardio into a workout so dynamic that the first session left me a crumpled mess on the studio floor.

Unlike other classes I’d tried, there were no pauses between each exercise in which my heart rate could slow. This was one continuous flow of graceful but gruelling movement that left my thighs burning, brow dripping and brain quiet – free from the worries I went in with.

The routine encouraged me to get outside and see sunlight first thing in the morning, which also helped to reduce my cortisol levels and regulate my circadian rhythms

While the recent study into aerobic exercise was conducted over the course of a year, I started to notice five signs of a lower baseline level of cortisol within just two weeks.

1. A better night’s sleep

Before swapping to increased aerobic exercise, I’d often wake up at around 4am. This can happen due to a premature cortisol spike, where the body’s natural early-morning rise (which starts to build in our system at about 3am) happens too quickly. After a week or so of sessions at PBB, I suddenly started sleeping through the night, meaning I had more energy and noticed less irritability when I chose to get up at around 6 or 7am each day.

2. No stress or comfort eating

Studies have shown that stress-induced cortisol can cause women to eat more. For a couple of years, I’d had a real problem with snacking and noticed myself frequently grabbing bags of unhealthy snacks – almost in a frenzy – and eating them in one sitting to self-soothe. After changing my routine, this urge entirely left me, and I’d stop eating each day by 8pm.

Without my nighttime sugary snacks, my blood sugar levels didn’t suffer a rapid spike and sharp crash. So, my body didn’t have to release cortisol to stabilise my levels. Meaning, this actually acted as a double whammy benefit when it came to my haywire hormones.

3. Less likely to have mood swings

I have, I admit, somewhat of a short fuse – particularly, if I feel stressed. So, when my cortisol levels are high, I notice I become particularly irritated in situations I wouldn’t usually be bothered by. I will, quite literally, cry over spilt milk and other such minute annoyances.

But within as little as a few days of changing my workout routine, I found myself much better equipped to deal with frustrating work situations, family or friend drama, or even small inconveniences like travel delays or cancelled appointments. I felt balanced and light.

4. Fewer remunerating thoughts

When it comes to worried or negative thoughts, my brain is like a dog with a bone – it just won’t drop it. While my new exercise routine didn’t entirely stop those thoughts from coming, it certainly helped me feel resilient enough to dismiss them when they arrived, rather than letting them taunt me for hours on end. In the opposite of a viscous cycle, this then boosted my mood and diminished the likelihood of these thoughts appearing in the first place.

5. A reduction in bloating

I have PCOS and endometriosis, so it doesn’t take much for my stomach to freak out and make me look five months pregnant. Whenever we’re chronically stressed, blood flow gets diverted away from digestion, which can lead to gut imbalances, bloating or worsening symptoms of inflammatory conditions such as mine or, for example, IBS.

While my chronic illnesses were by no means magically fixed by adding in more aerobic exercise, there was an amazing improvement in bloating, which helped boost my mood and body confidence, even if I was suffering from pelvic or lower back pain on some days.

The verdict

Simply by meeting the 150-minute weekly exercise goal set in this study, which can amount to as little as just over 20 minutes per day if you split it up over the week, I noticed the background noise of stress in my brain drastically diminished within the first month.

The routine encouraged me to get outside and see sunlight first thing in the morning, which also helped to reduce my cortisol levels and regulate my circadian rhythms. Plus, the increased number of workouts meant I was having more me-time, where my only focus was moving my body and calming my brain, rather than stretching myself too thin socially.

Notably, this was just month one. The long-term benefits of reducing cortisol include biological resilience against depression, anxiety and heart disease. Additionally, the group in the study showed a slower pace of brain ageing, meaning the habit could have advantages I carry with me long into later life, should I keep it up, which I feel way too good not to do.