High Achievers & Athletes,

Exactly one year ago, I started my coaching journey as a group class instructor @Mix.Brussels 

Whether if it's through social media, conversations or with your own researches, you have probably came across the term High Intensity Interval Training (or HIIT) at least once in your life. As a quick refresh, HIIT is a form of cardiovascular exercise that alternates short periods of intense anaerobic exercise with less intense recovery periods. 

Although we've been practicing anaerobic effort since the stone age (if you ever done a heavy stone walk, you know what I'm talking about), the concept of interval training is not new and has been verbalized in athletics for decades. HIIT mainly gained popularity during the 2000s and the 2010s through fitness programs and especially during the early rise of CrossFit.

The reason why HIIT became so rapidly popularized is mainly due to its time efficiency component. Numerous modern scientific research confirmed that short, high-intensity and repeated exercices were better than steady state cardio for a numerous of health & fitness outcomes. The mechanisms involved were increased cardiac output, elevated post-exercise oxygen consumption (EPOC), and hormonal responses that aid in fat oxidation and muscle adaptation.

Shorter workout durations compared to traditional exercise methods quickly became the norm.

"Why would I need to workout longer if I can have better results in less time?" is the question that most of us came across.

HIGH INTENSITY EFFECTIVENESS 

HIIT didn't become so globally famous for nothing. High Intensity Interval Training works (but as always, it depends on a bunch of different factors). 

For a quick physiological understanding, here is a brief overview of what HIIT offers and why you are probably addicted to collective classes that offer this type of stimulus (without even realizing it):

1. Enhanced Cardiovascular Efficiency: when you breath hard, you pump hard. Through HIIT, you'll most likely pump a lot of blood to your tissues. Your heart will therefore need to work at higher capacity which will improve your overall Cardiac Output and increase Stroke Volume. With such a high demand, your mitochondria (aka the powerhouse of cells) will have no choice than to be more efficient. A higher mitochondrial density improves the muscles' ability to produce energy, boosting overall endurance and performance.

2. Improved Metabolic Rate: this one was widely spread out and quickly understood for the one's that were interested in losing weight. After a HIIT workout, the body continues to consume more oxygen than it would at rest, leading to an elevated metabolic rate for hours post-exercise. This "afterburn" effect increases calorie expenditure and can therefore help with fat loss. 

Metabolic wise, you might have heard about insulin sensitivity. Well, higher effort output increases insulin sensitivity which means cells are better able to use glucose for energy. This is particularly beneficial for managing blood sugar levels and reducing the risk of type 2 diabetes. Considering hormones, the intense nature of those workouts stimulates the release of anabolic hormones like testosterone and growth hormone (GH), which promote muscle repair and growth.

3. Muscle Adaptations: HIIT recruits both slow-twitch (endurance) and fast-twitch (power) muscle fibers. This dual recruitment improves overall muscle strength and endurance.

4. Fat Oxidation and Weight Loss: other than testosterone and GH, HIIT increases the production of catecholamines (like adrenaline), which stimulate fat breakdown. It also reduces insulin levels, which helps in mobilizing fat stores for energy.

If you have been on a weight loss journey at anytime, you also have probably paid attention to cholesterols. Another benefits of HIIT has been shown to improve cholesterol levels by increasing HDL (good cholesterol) while reducing LDL (bad cholesterol) and triglycerides.

5. Time Efficiency: we have already talked about it... "Short duration, high Impact" is what we are after. As life is busier than ever, hoping on 30-50' collective class without worrying about anything else than to show up definitely makes those session time-efficient. 

6. Neuromuscular Adaptations: with those type of efforts, you more than likely need to move your body through space which can lead to better neuromuscular coordination, agility, and balance, leading (theoretically) to better physical capacities. 

7. Psychological Benefits: this is the one that I look after the most. Mental perseverance is improved to confronting hard and challenging situations. The challenging nature of short burst of effort can improve mental toughness and resistance. 

Down the line, this phenomenon can leads to a reduced perception of effort during those intense activities, making other physical activities feel easier. Added to that, those mental traits you develop by harnessing through discomfort can be translated to other areas of your life. 

THE OTHER SIDE OF THE COIN...

Reading this, you might prep yourself up to smash a brutal HIIT session. Well, consider following through ...

During the last 365 days, I've been able to witness and analyse a few interesting things with the BURN classes I've taught. 

Coming from a CrossFit coaching background, the "GO HARD" mantra is ingrained in me since a long time. But the thing I've never believe in and understood is to "GO HARD UNINTENTIONALLY"

See, all of the above benefits I've just listed are impactful once your fitness foundation is built and when you move with deliberate purpose. 

What do I mean by that? 

THE FITNESS FOUNDATION

Building fitness takes time, consistency, discipline and effort. If you don't start building your house from the ground up, it will eventually crumble or never exist. The same principle applies to your fitness. If you begin your fitness journey by only attending to fast and hard workouts, you miss the key elements of true fitness: 

Building more muscle mass in order to have a stronger body, a higher metabolic expenditure and the body composition you are looking for. During short bust of intensive effort, you usually don't have enough volume in order to generate enough stress and muscle tissue breakdown - thus, not increasing muscle fiber size (hypertrophy). You are working and sweating yes, but you are not creating sufficient muscle damage.
You are also not in the environment to recruits a lot of muscle fibers through compound lifts that teaches you to lift heavier loads.
 

Learning How To Properly Move: again, with the fast and quick component of HIIT, you can't focus properly on MOVING WELL. Learning to move you body efficiently requires you to slow down and to focus on proper biomechanics, positions, coordination, placements, mechanical tension and muscle recruitments. As you are properly thinking of SURVIVING instead of THRIVING, movement quality perish. Working out with only this mantra leads overtime to poor movement understanding, higher risks of injuries, and overall poor fitness.
 

Solidifying The Mind Muscle Connection (MMC): MMC takes time to build. A new fitness trainee doesn't have the same nerves connections then an advance athlete that has already done dozen of repetitions and utilized those recruitments over and over. Generating a pump is the result of great muscle contractions, proper weight selection and blood volume to the targeted zones. Not taking the years (not months) to build those MMC will leave you unprepared to properly connect your muscles while you are doing a physical activity or any demanding exercices. 

Constantly Varied Exercises Leads To Random Results: Zig Ziglar beautifully said: "Repetition is the mother of learning, the father of action, which makes it the architect of accomplishment."

It's through repetitions that habits, improvements and growth occurs. Constantly attending to classes that doesn't follow a structured and repeatable sets of exercices is like if you were moving to a new city every day. You continuously lose your point of reference and you don't have the time to acclimate to the stress you are experiencing. 

HOW TO HIIT HARD? 

Now, knowing both sides of the coins, how can you implement HIIT in your week knowing the benefits it offers? Again, it depends.

My personal recommendations if you are still in the beginning of your fitness journey would be to keep one or two true high power output sessions of maximum an hour per week. If you are consistent over the weeks & months with this type of stress stimulation and that you can recover from it, then it is plenty. As long as you are following a thoughtful training program with 2-4 resistance training sessions per week that teaches you how to properly move and is progressive in nature, the stimulation from the HIIT workouts will just be the icing on the cake. 

For intermediate and more advanced athletes, you will obviously be able to tolerate more stress than in the early stages. Depending on your fitness goals and experience, spreading bursts of intensity through the week that is part of your training plan is a much more intelligent way to improve your fitness/skills compare to increasing the frequency of dedicated HIIT workouts. The time and effort you will be much more controllable and repeatable than to continuously just send random High Intensity classes for the sake of saying "I've worked out".

Remember that progress isn't only measured with the intensity you bring or the amount of sweat you have at the end of your workout.

Lifting heavier loads, improving your MMC, being more fluid (and less stiff) with certain movements, doing more reps & sets, reaching for longer range of motions are all sign of improvement & growth that you slowly build.

_________________________

If you want to create a fitness that remains for a lifetime that allows you to have a higher quality of life, build the foundation first, train hard, gradually learn how to utilise different skills, energy systems, and be patient. The more complex stuff can come later. 

Passionately, 

Max & Ben 

Written by Benjamin Desmet 

If you enjoyed reading this email, you can support us by spreading it to the word. Hit the forward button, share it with a friend and tell us your thoughts! We love to hear back from you.