When Kay Lewis decided to run CCC, the 100k race at the UTMB finals event, her success criteria didn’t just entail finishing. She wanted to finish with dignity, and she wanted to achieve that by training in a way that wasn’t too punishing on her body.

For Kay, staggering across the line a broken woman would be a failure of sorts. She wanted to finish the race thinking, “I’d like to do that again.”

It’s no surprise that she turned to low heart rate training as the key, because in one way or another she’s been doing it for decades. Kay says her mindset has always been that there’s no need to “be busting your gut on every training run”.

With that in mind back in 2015, when she first started running trail ultras, she adopted the Maffetone Method, a training regime devised by Dr Phil Maffetone which involves training at a low-intensity aerobic heart rate.

This approach became central to Kay’s running philosophy, more by happenstance than through any grand plan. “It’s pretty much been my thing since, not overly intentional,” she says.

“But when I started doing it seriously for CCC, I looked back at my Strava data and The Uphill Athlete talks about 80-90 per cent of your training should be in zone two or one and I pretty much did 80 per cent anyway.”

She’d unintentionally spent more than a decade building an ideal low heart rate foundation.

This removed one of the big barriers many runners face when they first adopt a low heart rate approach. “It worked so well for me because I didn’t need that really big time period some people need [to adjust],” Kay says.

But she still struggled with other aspects of the approach. “It was incredibly frustrating to start with because you do end up walking stuff that you know you can run. And the isolation… I did hardly any runs with anybody.”

If you’re a social runner, it’s this isolation that hits hardest. Unless a bunch of you decide to become low heart rate runners at the same time, you have no choice but to run most of your runs solo because your pace is dictated solely by your heart rate.

But for Kay, this was a sacrifice she was prepared to make. “I knew if I was gonna do it I was gonna do it properly, so I had to suck that up.”

There are a variety of different approaches to low heart training, but Kay chose the system championed by coach Scott Johnston and set out in the book he co-wrote with Steve House and mountain running legend Kilian Jornet, Training for the Uphill Athlete.

Johnston became an overnight sensation after the 2024 UTMB, having coached both the men’s and women’s winners in the big race - Tom Evans and Ruth Croft. Johnston’s approach combines low heart rate training with specific strength training.

I’m planning a full piece on the science behind low heart rate training, and it’s a complex area with both plenty of unknowns and nuances from individual to individual, but The Uphill Athlete’s philosophy works like this.

When we exercise, we build up lactate. This can be turned into energy in one of two ways: oxidised by mitochondria in our cells and turned into fuel, or converted by the liver into glucose.

If lactate isn’t cleared in one of these ways, it builds up until we exceed our lactate threshold. That’s the point, and we’ve all been there, where our bodies just say, “Nope, this is too hard. I quit!”

So the trick to running long distances is to maintain an effort that produces enough lactate to turn into fuel, but not so much that your body says, “No!”

Mitochondria are important because they help transporter proteins to clear the lactate by moving it into muscles. And as a bonus, along the way they convert the lactate into fuel.

Low heart rate training increases our mitochondrial density - the number of mitochondria in our muscle cells.

The more mitochondria you have, the greater your capacity to turn lactate into fuel, which allows you to maintain effort. In other words, the more mitochondria the faster you can go for longer without raising your perceived rate of effort.

The Uphill Athlete uses a vacuum cleaner as an analogy. So let’s build on that and imagine I’m in my workshop doing some woodworking. As I’m sawing timber (running), I’m producing sawdust (lactate).

The faster and longer I saw (run), the more sawdust (lactate) I produce. At the same time my workshop assistant is vacuuming the sawdust (lactate) up as I saw (run).

If my assistant uses a dust-buster (low-density mitochondria), pretty soon the workshop (my muscles) fills with sawdust (lactate) and we have to stop. But if my assistant is using an industrial-strength vacuum (high-density mitochondria), then, over time, I can saw (run) faster and faster for longer and longer without ever reaching the point where I’m up to my knees in sawdust (exceeding my lactate threshold).

(For this analogy to really work, there would need to be another process turning that sawdust into pastries for me to eat, and full disclosure: I don’t have a workshop and I’m hopeless on the tools.)

Kay was all in on this philosophy (the low heart rate training, not the woodworking). She bought Training for the Uphill Athlete and a 20-week program specifically tailored for the CCC race. She put the program into Training Peaks, an app that makes tracking training data and progress relatively easy.

One of the first things Kay had to do was figure out her training zones. In short, this is a five-point scale (mostly, but is sometimes expressed as a three or seven point scale) that indicates how hard you’re working during exercise. Zone one is walking, zone five is working at maximum intensity.

For each zone, we each have a heart rate that corresponds to that zone. For example, Garmin lists this as the beats per minute figure for my zones:

You should read absolutely nothing into these numbers. For a start, it’s my Garmin’s best guess. Secondly, as The Uphill Athlete puts it: “Let’s be clear that your metabolic response to exercise does not fit neatly into discrete zones with hard boundaries …

“Not only is there a great deal of variation between individuals, but there is some variation from day to day for each athlete.” But it’s a pretty good guide and, apart from perceived rate of effort, it’s the best we’ve got.

Needless to say, Kay didn’t ask her watch for her figures. She followed the advice in the book and put herself through a number of tests involving sustained effort at different intensities to discover her Aerobic Threshold - the bottom of zone three, and her Lactate Threshold - the top of zone three.

When she’d completed this process, Kay had one magic number top of mind: 146. That was the maximum beats per minute for her to remain in zone two. During every training run, her aim was simple - keep her heartrate at 146bpm or below.

That inevitably meant hiking the uphills. It sometimes even meant walking the downhills. But she had a plan and she was sticking to it. “The hard science works for me,” she says.

Another key element of Kay’s plan was to match her training runs as closely as possible to the course. CCC has around 6,200m of elevation in the 100k course. So Kay trained on routes around Brisbane that averaged 62m elevation for every kilometre.

She compiled a list of potential routes that ticked that box. Brisbane is not the Alps, so it was a short list! “It was just really Black Soil, Black Soil and a little bit of Camp Mountain. I got to know Black Soil intimately,” she says.

When Kay dug out her mileage chart from the program, she was surprised - there weren’t as many big weeks as she’d expected. Of course, I looked at the list and it’s fair to say that wasn’t my impression…

Strength training was another key element of Kay’s plan. But not any strength training. The Uphill Athlete makes it clear - “general strength” is non-sport specific. It’s great, but it won’t make you a better runner. Instead, you should be aiming for “specific strength”.

This, the book says, “mimics quite closely (exactly, in some cases) the demands of the sport. This type of strength training has a direct bearing on the athlete’s performance in that sport”.

What does this mean for running? Exercises like squats, box jumps, lunges, squat jumps and split squat jumps. Being a Kiwi and therefore a Ruth Croft fan, Kay also added three 20-minute weighted vest uphill hikes per week because they featured in Croft’s training plan before her success at UTMB last year.

The strength program sounds pretty serious. “I had to run for 20 minutes, then I had to do jump squats and box step ups with my weight on. Six sets of 10. Then I’d have to have 60 seconds recovery,” she says.

“So there were times when I was doing 340 split squats. But it’d take me an hour and 15 to get through the whole lot because I’d have to have 60-second breaks then five-minute recoveries… so it was quite intense.” You can say that again.

All this strength work paid off as Kay found herself turning the tables on her husband Paul, who’s also a seasoned trail runner. “Paul usually leaves me for dead hiking up hills, but [in the lead-up to the race] I left him for dead. So it was really, really evident that my legs were good. They were strong.”

Through all this, Kay was also training her gut. The best laid training plans in the world are useless if you can’t keep any calories down on race day. Again, Kay took a scientific approach to this.

During training, she aimed to consume 100g of carbs per hour. She knew there’d be times she’d drop below that, but if she set the high-water mark at 100g, the hope was even when she didn’t feel like eating, she’d still be taking on around 60g.

Perhaps the biggest benefit of her low heart rate training regime was that Kay never really felt tired. Because she was working at a low intensity she recovered quickly. This meant she was able to stack good training efforts back-to-back-to-back.

For the final five weeks of her training block, Kay was in the Alps, running segments of the course and acclimatising. And she felt fantastic.

“All my training runs over there, I would get to the end and I would be full of energy, even after eight hours. So I was really confident going in,” Kay says.

Her preparation had gone almost flawlessly. Now all that remained was to put it together on race day.

There are way too many events for me to list everything that’s happening around the country, but here is a selection of upcoming races (with a bias towards South East Queensland).

The Running Calendar website is a great source if you want a comprehensive understanding of what’s available around the country.