We’ve seen the clean eating trend taken to the extreme with cases of orthorexia, but what about our HIIT habits? We find out when pushing yourself should come with a health warning

Any products in this article have been selected editorially however if you buy something we mention, we may earn commission

Could your exercise habits be doing your health more harm than good? Few training techniques have captured the public’s imagination more than HIIT  has in recent times and looking at how its vital stats stack up, it’s easy to see why. Convenient and widely available with at-home and gym options available, accessibility factors highly in the rise of the ‘fast fitness’ phenomenon. However, while it’s getting more of us moving (never a bad thing), some of us could be HIITing it too hard by overtraining and shunning the essential recovery time needed to keep stress-related injuries at bay.

“Overtraining is when training load (i.e. volume, intensity, frequency) exceeds an individual’s ability to recover,” says Doug Tannahill, Head of Strength & Conditioning at BXR London  and health optimisation clinic, CHHP. “This ability differs from individual to individual depending on many factors like age, sleep, genetic potential and stress.” With the demand for group exercise studios and HIIT increasing, so have instances of overtraining and as a result, the occurrence of associated lower limb injuries, ligament and tendon problems and hip and shoulder impingements - a worrying trend that Doug’s seen in a number of his clients during his time as both an osteopath and fitness specialist. Those who are new to fitness could be the most at risk. “The problem with the rise of HIIT training is that many individuals (especially those beginners with the best intentions to get fit) are using it as their sole modality of training,” says Doug. “Often the intensity of the training, combined with the frequency (often daily) is too great a load for people to recover from and some symptoms of overtraining can occur.”

Recovery time is a key part of an effective workout regime and pushing ourselves too hard could be impeding the results we’re looking for. “What people fail to realise is that the improvement of your body actually comes about when you rest,” Doug explains. “The exercise is the stimulus which your body then responds to and repairs/grows when you rest. If the overall stimulus is too great, then your body can’t recover and enters a state of continuous breakdown.”

Are we a generation of ‘class junkies’?

The sheer volume of classes and fitness venues we now have available to us plays a vital role in the rise of overtraining too. Significant growth has been seen in 'pay-as-you-train' platforms over the last two years, and while fantastic from a choice perspective, it can result in our fitness plans becoming increasingly muddled. “'Pay-as-you-train' platforms were originally designed to deliver a non-commitment level of training to cater to a market of new users who didn’t want to be tied into a membership for 12, 18 or even 24 month contracts,” says James Pisano, Fitness Director at Sweat by BXR . “This was quickly diluted though and clients started using multiple gyms for their workouts, trusting many different views to direct their fitness programmes. This means we now have people using two to three gyms for multiple sessions per day to workout.” As a result, many of us are overworked and under-rested. “The recovery curve being cut short means their goals aren’t being reached and so they assume they need to workout even more,” says James, “Which just feeds into the system.”

Resulting in a new generation of ‘class junkies,’ an approach of quantity over quality is fast becoming the new norm among not just consumers, but some gyms too. HIIT isn’t a bad thing, in fact, it’s a hugely effective form of exercise - just as long as it’s done safely and properly. “HIIT training is without a doubt a very time efficient workout for burning calories, (which appears to be the main marketing focus), increasing your metabolic rate and increasing muscle endurance,” says personal trainer, Christina Howells . “Unfortunately though, there's a shift towards ‘beat the hell out of you classes,’ which can sound like a great idea but where's the focus on quality of movement - how many people can you spot with correct form? Do you know if your own form is right? The hardest workout you will ever do may not necessarily be the best workout for you. Often this results in a buildup of metabolic waste and that feeling of not being quite up to par - a weakened immune system, muscle and joint aches and if you’re not careful, injury.”

Are you an over-trainer?

The signs are easy to spot, although some of us are probably unaware that they're equated with overtraining. “The symptoms that are most often experienced in the average gym junkie are increased injury prevalence and persistent muscle soreness,” says Doug. For more experienced gym goers, high performance athletes or other individuals who are able to sustain a very high level of exercise volume for a sustained period of time though, Doug also highlights the below:

  • Increased resting heart rate
  • Irritability
  • Depression
  • Insomnia (trouble sleeping)
  • Decreased appetite
  • Weight loss
  • Decreased motivation
  • Increased incidence of illness

Taking a closer look at how we speak about exercise could also provide a valuable insight into our training frame of mind. “Most overtrained clients appear dissatisfied after training unless they have been pushed or ‘broken,’” says James. “They will almost certainly have a number of small issues or injuries which they are ‘working on’ or ‘pushing through.’”

How can you avoid overtraining?

The amount of training load that someone can take on without impeding their ability to recover differs from person to person. However, there are some key considerations that are good to keep in mind to avoid workout burnout.

Firstly, don’t let HIIT workouts be the main focus of your exercise regime and adopt a balanced weekly exercise programme. LISS  is just as important as HIIT, as are other modes of training too. “People might benefit to change their mindset into thinking that you have to train to partake in HIIT, rather than use HIIT as their only form of training,” says Doug and this wider picture approach is echoed by Christina too. “HIIT is a great tool, but not your only tool,” she says. “You need to think of your exercise week like an athlete thinks of their training week. Don’t drop your HIIT session, but do plan your weekly schedule so you plan in active rest from HIIT, working at a lower intensity or incorporate a different discipline such as bodyweight training or yoga, as well as pure rest days too.”

Giving yourself sufficient recovery time is a pivotal part of an effective and sustainable workout regime and how long that is, is specific to the individual. “Optimal recovery varies from person to person,” says James. “I would always aim to have a rest day on the fourth day of a weekly programme and even more than that, I would rest one group or element and challenge another every other day...you need to be smart about your programmes and we have a lot of great places that will encourage mobility classes as a part of your development.”

Finding a trainer to advise on correct technique can be helpful when it comes to starting off on the right foot, eliminating bad habits and limiting you if you’re injured. “Ideally, make it a trainer or gym you know or have been recommended and where you feel comfortable with asking questions regarding workouts,” says James. He also advises focusing on the fundamentals. “Ensure the workout is simple and has the ability to push you with the workload not the complexity,” he says. “Simple is always best in almost every element of exercise. Plus, make sure you know what it is you’re trying to achieve. HIIT has many names but effectively you are trying to condition your body while challenging your cardiovascular system. If the workout says some kind of magical formulae which sounds like nonsense - unfortunately it might be just that... so steer clear.”

Mixing up your HIIT intensity will also go some way to helping reduce wear and tear - it shouldn’t be at its highest from the get-go. “One of the biggest problems is most people do not have the pre-conditioning for the HIIT class they’re attending, and therefore they can’t perform the exercise correctly at the intensity required,” says Christina. “The key is to find a class that has regressions and a focus on form. This is important to look for when choosing a class online too."

She adds, "With online programmes, I would choose ones that offer HIIT as part of their format or if you want just HIIT, to make sure there are regressions and progressions and use this twice a week as part of a rounded fitness programme. In our That Girl programme, the first weeks are all about technique and learning skills and our HIIT section starts at week 4 or 6 and we provide different levels.”

And finally, what can you do if you’ve overdone it?

“Train hard, rest harder!” says Doug. “Take some time off training and/or have a few days in the gym focusing on ‘working in’ rather than ‘working out’. Focus on mobility, yoga or another low intensity exercise. Make sure your nutrition is on point and sleep to support tissue recovery.”

Some of our favourite mobility-focused exercises and classes include Stretch at barrecore (recommended by the GTG team as being particularly great for your fascia), a gentle swim, yin yoga at Triyoga (a good choice if you like a mental challenge) and hot yoga at Another Space. James also recommends trying Sweat by BXR’s Mobility class to help the body recover, which is vital before it gets stronger. “The recovery curve shows us that the less rest we take, the less effective we become which means the less productive the workouts are which means unfortunately, that our goals are less achievable,” he says.

Lastly, up your water intake. “Dehydration has so many negative effects on the human body but poor functioning, tired and even cramping muscle tissue is the most common in this industry. So drink up!”

Follow Ayesha on  Twitter  and  Instagram .