With a company focus on LES MILLS GRIT, you’re going to be seeing lots more of this program over the next six months as we shine a spotlight on the many benefits of teaching and participating in HIIT. Last month, Erin Maw explained the benefits of coaching LES MILLS GRIT; today we catch up with the expert behind the science, Dr Jinger Gottschall.

Let’s start with the basics, how do you scientifically define what HIIT is?

High Intensity Interval Training is where your heart rate is above 85% for two thirds of the total duration. Typically, 30 minutes is the maximum amount of time that individuals can perform HIIT with quality.

Can you explain the process and timelines behind the testing of each LES MILLS GRIT™ release? Ie how you test it, how many people are involved, how many times, where, what you are looking for…

Initially, I receive a draft of the release format, work and rest intervals, as well as the exercises that Les [Mills Junior], Corey [Baird] and Erin [Maw] create. Erin also films the exercises so I am clear on the execution.

Next, I trial the workouts with three to four LES MILLS GRIT experts, individuals who have been training with LES MILLS GRIT for over five years.

After these initial sessions, I am more familiar with the workout and how to coach it, so then I trial each format separately with 20-40 people ranging in age from 20-55 years and varying abilities. For all of these sessions, I collect heart rate data to calculate the amount of time each individual is performing in the different zones, more specifically 85-100% heart rate max.

Next, I send the data to Bryce [Hastings] who evaluates the results and discusses the data with the team in New Zealand!

If there is a novel exercise with potential risk, I also perform ground reaction force tests to ensure repeated movements are safe for the joints. Intensity testing is performed at FITOLOGY [Studio] and force testing is completed at Penn State.

If you’re not getting the intensity right, how do you adjust the workout to ensure it’s hitting those peaks?

There are a few ways to make adjustments… typically we modify or replace a particular exercise… but we can also adjust interval times or the order of tracks. In the last 6+ years we have learned a TON about how to develop the ultimate 30 minute HIIT session! For instance, longer intervals at the beginning of the session and a specific ratio of lower/upper body exercises.

Your study last year demonstrated that there is an upper limit to how much HIIT people should be doing. What should LES MILLS GRIT Coaches be telling their members about this?

Unfortunately there can be TOO much of a GREAT thing! HIIT training, above 90% max, should only make up about 4-9% of your total training time. So if you exercise 6 hours per week, then 20-30 minutes of HIIT, or one LES MILLS GRIT, is ideal. This amount of HIIT training will maximize your fitness without causing high stress and high injury risk. In short, one to two LES MILLS GRIT sessions per week, on non-consecutive days is the best!

There are a lot of things that are positioned as HIIT but aren’t all necessarily meeting what is scientifically defined as HIIT. How do you know that what you’re teaching is going to deliver the HIIT effect?

That is one of the unique aspects of LES MILLS GRIT… it Is tested so that you have the confidence that the sequence of exercises for the durations in a release will deliver the results you are hoping for… I also encourage individuals who want to take their training to the next level to purchase a heart rate monitor (Polar A370) with a chest strap (Polar H10). This simple addition will provide real data on your training intensity so you can create the ultimate weekly plan.

How do you think LES MILLS GRIT compares to other products in market?

I am not aware of another HIIT product that places such an emphasis on testing every single session for both intensity and safety. It takes additional time and money that most companies are not willing to invest.

Why should Instructors teach LES MILLS GRIT over other interval based classes?

LES MILLS GRIT provides an extra level of confidence to the instructors. You are given all the tools to lead a safe, effective training session. The combination of the choreography notes and videos set you up for success.

When someone is first starting out at the gym, how should they build up to attending LES MILLS GRIT?

The first step is building up to doing three cardio classes (BODYATTACK™, BODYCOMBAT™, BODYSTEP™, RPM™) and two strength (BODYPUMP™) per week consistently for three to six months (depending on initial fitness). Then when the individual is ready for a new challenge, add in one LES MILLS GRIT per week!

Is LES MILLS GRIT for everyone?

I would not recommend LES MILLS GRIT to individuals who are under 16 years, new to exercise, not currently exercising, pregnant, or suffering with a current injury.

What’s wrong with doing LES MILLS GRIT everyday?

Working at this intensity multiple days in a row does not allow you to recovery and reap the benefits from your HIIT training. This training produces a stress response where if overdone, can lead to cause fatigue, joint pain, and mood disturbances… but with the right amount of HIIT, one to two sessions per week, this stress response can help control blood sugar, regulate metabolism, reduce inflammation, and improve strength.

What’s wrong with doing only LES MILLS GRIT and nothing else?

Performing lower intensity cardio and strength training provide benefits to cardiovascular and muscular health that does not come from LES MILLS GRIT. In addition, despite the format, LES MILLS GRIT is a CARDIO workout! So continuing to complete BODYPUMP and CXWORX™ are critical for injury prevention at both the muscle and joint level.

What do you get from teaching other classes that makes you a better LES MILLS GRIT Coach?

The Les Mills coaching model in the other formats assists in HOW to describe the exercises, HOW to communicate efficiently, and WHERE you should feel the activity. They train you to be in the moment. As a LES MILLS GRIT coach you have to think quickly and explain clearly… you also want to be acutely aware of what is happening with your athletes at all times and who needs what type of motivation. It is challenging and rewarding!

Jinger Gotschall, PhD, is an Associate Professor at Penn State University who has led numerous studies into the effectiveness of various exercise regimes. Working closely with Bryce Hastings, Les Mills Head of Research, Dr Gottschall regularly tests the effectiveness of LES MILLS programs, helping ensure that exercisers get the best results from the time they spend working out. In addition to her research roles, Dr Gottschall is also a Les Mills instructor and fitness studio operator.

LES MILLS GRIT is set to be the hottest program of 2019. Find a training near you here.