The Pros and Cons of High Intensity Interval Training (HIIT)

You may be familiar with this acronym or heard this term used frequently in the gyming and fitness world, but what do we know about it, and what benefits can be gained by utilising it?

What is HIIT?

HIIT is an acronym for High Interval Intensity Training. Over the years it has grown in popularity and has been widely promoted, with numerous gyms and fitness classes using the basis of HIIT to design their workouts, programming and ethos. Taking part in HIIT training claims that the client will gain the edge in getting fitter, leaner and overall stronger, using interval training workouts that alternate between periods of high-intensity anaerobic exercise, followed by (less intense) periods of recovery and for a shortened amount of time- 30-minute sessions seem to be the trend.

The Benefits of High Intensity Interval Training (HIIT)

· HIIT Can Be Done Anywhere!

In a pandemic world, more and more people have found themselves unable to attend the gym in person but have found themselves eager to continue their fitness momentum. One of the beauties of HIIT is that it's accessible and it can be achieved at home using your own plan or via online workouts which flood the internet and doesn't require expensive or specialised equipment- just some motivation, a patch of floor space and WIFI. With the click of a button, you can find many free HIIT workouts to download or workout with! This is also helpful to those who are not so comfortable exercising within a gym yet and would prefer the privacy of their own home to get all sweaty and give all to the workout! Sometimes working out in a gym or a class can be intimidating, so home workouts can be a great way for you to build your confidence (and your fitness).

· Burns More Calories in Less Time

Research shows that taking part in a 30-minute HIIT workout burns 25-30 % more calories than alternate forms of exercising ( 1). This can be a great selling point for the reluctant gym-goer or exerciser, as it can be seen as getting more for less. Who wouldn’t be motivated to burn a great number of calories for only 30 minutes of near-death suffering?

· Immediate Gratification

For some of us, for us to believe we've done a workout, we need to feel like we’ve done a workout. That usually means being desperately out of breath, questioning why you’ve turned up to the class in the first place, and semi-drowning in your own pool of sweat.

Despite this, there’s a sense of accomplishment when you’ve reached this level of exhaustion, and as daunting as it seems, feeling this way gives you a sense of (immediate) achievement and accomplishment. There’s a believability to this feeling- the, “Yes, I’ve just finished a good workout!”. More so, for example, than completing a gym programme consisting of mostly weight and strength training, i.e., lifting a dumbbell for 3 sets of 8 repetitions, or 4 sets of 10 deadlifts. Though both have great benefits, there can be a more sense of immediate accomplishment and achievement with HIIT workouts where you’re out of breath and considering the possibility that you may have asthma.

· Calories Continue to Burn Post-Workout

The benefits of this relate to the EPOC (excess post-exercise oxygen consumption) theory, where after you have completed your workout, your body will continue to burn calories at a rate that is higher than normal for 24 hours, as your metabolism continues to be elevated ( 2).

· Reduces Blood Pressure and Heart Rate

Studies show that taking part in HIIT workouts can reduce resting heart rate and blood pressure in overweight and obese individuals (3, 4, 5 ).

· Promotes Fat Loss

Not only do you burn more calories with HIIT workouts, but combined with the aftereffect of HIIT where you continue to burn calories after your workout, you're on the right track to losing fat! HIIT workouts are known as the ‘fat melting’ workouts, achieved by moving vigorously over a short period, and produces a higher reduction in visceral fat than would be achieved with moderately paced exercises such as walking or cycling ( 6). Also, HIIT forces your body to use energy from fat as opposed to carbs which make losing fat more efficient.

· Can Improve Mental Health

Many people agree that a good workout not only makes them feel better about themselves but also helps to set up and/or finish the day off well. Research has looked at the impact that taking part in HIIT workouts has on mental wellbeing and it has shown to reduce symptoms of stress, anxiety and depression ( 7 ).

· Improve Bone and Joint Health

Having brittleness within our bones has the potential to lead to greater and longer-term issues and is a factor of concern as we age. Studies undertaken to look at the impact of HIIT workouts on bone and joint health gave promising results. In one study, older adults who undertook HIIT workouts for 10 weeks saw a 38% decreased progression of their rheumatoid arthritis, a 55.8% reduction in the swelling of their joints, and, for post-menopausal women, 16% improved bone density after 24 weeks ( 8).

· Improves Blood Sugar Levels and Insulin Resistance

Studies support that undertaking HIIT regulates our blood sugars more than standard exercise programmes, and improves our insulin resistance ( 9 ). When performing HIIT workouts the fast-twitch muscles in the body are stimulated into taking up glucose from the blood to use as fuel. As a result, our blood glucose concentrations in the body decrease.

Things to Consider with High Intensity Interval Training (HIIT)

· Workouts Can Be Demanding

If you don’t have a reasonable amount of training behind you already, your body can be put under a lot of strain so it’s important to start at a reasonable pace in the beginning and build your body up.

· Adequate Rest

During exercise, our body first taps into fuel that is quickly available for processing. Once this is used up, it then uses glycogen which is stored as a carbohydrate form in our muscles and liver. Glycogen stores are replenished during rest (not rest during the workouts, rest between workout sessions). With workouts like HIIT, if you don’t rest long enough between workouts these stores won’t have time to be replenished, resulting in a person feeling weak and slower during workouts (10). This can also negatively affect your body’s recovery. It’s important to get adequate rest between HIIT sessions to give your body time to replenish its glycogen stores, and so your body can recover.

In general, two-three HIIT sessions a week is a good place to be sitting around, allowing for rest and healing in-between.

· Hydration

You tend to lose more water during HIIT than other types of exercise so it’s important to stay hydrated before, during, and after a workout.

· Impact on Joints

High impact movements such as box jumps, squat jumps and burpees can increase our risk of injury and pain if our technique is not checked on and the movement is done incorrectly- which can be a factor if we have weakness or conditions already in our joints or we try to move at speed and let this compromise our technique and overall safety.

Is High Intensity Interval Training for Me?

HIIT workouts can be very beneficial and offer good results, but proper caution is always needed from both the participant and the coach when undertaking these workouts. Having pre-existing health conditions or injuries can be triggered and aggravated by these types of workouts where you do put your body under strain and stress. It's important to always consult with your medical advisors before these workouts are undertaken and to be consciously reading your body for signs that the intensity needs to be scaled back.

To Sum Up

HIIT workouts can create amazing results with fitness and weight loss! Many successful global fitness programmes such as F45, Orange Theory, Les Mills and CrossFit have shown the success that HIIT workouts can bring, with thousands finding great fitness success and fun by taking part. (HI)IT’s a style of workout that has a huge following and is still gaining even further traction in the world. If you’re a HIIT devotee congratulations and keep it up! If you’re new to it or curious to get involved, seek some advice from your coaches and your medical advisors and then give it a go!

Author - Paulo Vaa

Writer & Podcaster