If you’re someone who uses cardio-based training, such as running, cycling, swimming or rowing as your main fitness activity, and you’re training for a race or just keen to improve your performance, then it’s likely you’ve wondered what the best way to get faster is. It’s something I spent years working on as a keen marathon and ultramarathon runner, and more recently, while helping others as a personal trainer and running coach. When I explain that the best way to get faster for a race or event is to take it slower while training, it still surprises 99 per cent of people I tell. But it’s a tried and tested method, not just by me, but many elite athletes, including Olympic swimmers and rowers, as well as marathon and Tour De France winners.
Hannah Eden is an iFit running coach and elite Iron Man athlete, who started using the slowing down method while training for her first triathlon. She noticed a huge improvement in her performance. “I was blown away by how long I could keep up a higher intensity output when I really hadn’t been training at this intensity at all. So it sounds counterintuitive to run or cycle slowly, but it absolutely works. It’s a pretty crazy feeling.”
How does it work?
“Training at a slower pace is a method used by athletes to build a stronger aerobic base – the body becomes a lot more efficient at using oxygen, which improves our overall endurance,” explains Eden. “The lower intensity training helps increase blood flow to the muscles and enhances oxygen uptake, making it easier to perform high intensity activities as the body starts to adapt, delaying fatigue, and helping you to go for longer during the harder and faster sessions.”
This build-up of aerobic fitness comes about because the slow training improves the efficiency of your cardiorespiratory system, which supplies oxygen and nutrients to your muscles via the bloodstream. This makes your muscles better at converting fat and carbohydrates into energy as you train. Specifically, “training slow actually enhances the body’s ability to metabolise fats to use as a main fuel source, helping you improve your cardiovascular efficiency,” says Eden.
What’s fat got to do with it?
When we train hard, at a higher intensity and higher heart rate, the body uses mostly carbohydrates (known as glycogen) for energy. We only have around 1500 to 2000 calories of glycogen available in the body so, we can only go “hard” for so long before fatigue sets in. But when we train slowly at a lower heart rate, we predominately use stored fat for energy – and the body has an almost infinite source of this.
“Stored fat is a better source of energy as it releases more energy, more efficiently,” explains Dr Raija Laukkanen, director of Science Collaborations at the Polar Research Center, which specialises in fitness watches, trackers and heart rate monitors. “Slow training means that your body becomes better adapted to burning fat, which will help your body’s fuel consumption for faster runs and rides. Utilising fat can help you avoid the energy crashes that come when your body uses carbohydrate for fuel.”
Dr Laukkanen goes on to add: “Although slow training is not intensive, the amount of oxygenated red blood cells produced will nonetheless be close to their maximum level and do not increase significantly as training intensity does. It is this base that allows the muscles to receive the oxygen they need during more intensive running and cycling sessions.”
So, how slow should you go?
Most athletes use a method known as “zone training” to figure out exactly how easy their workout should be. It involves splitting your workout effort into three or five zones depending on how technical you want to get – most elite athletes use the five zone method. The zones represent your heart rate while training, and by doing most of your training in the lower heart rate zones of one, two and three you can keep your workout at a low intensity that utilises predominately fats as energy.
Many smart watches will automatically work out your training zones based on previously recorded fitness sessions, and have a setting to show which zone you’re in as you work out. If you don’t have this function then Dr Laukkanen explains how to understand your zones once you know your maximum heart rate (HRmax). “Your maximum heart rate can be (roughly) estimated with a commonly used formula of 220 minus your age. If you already train with a heart rate monitor or sports watch, just look at the highest maximum heart rate recorded after a maximal training session.”
You can then work out your specific zones using Polar’s heart rate zone calculator or “zone one is 50-60 per cent of your HRmax, zone two is 60-70 per cent and zone three is 70-80 per cent.” Once you enter zones four (80–90 per cent of HRmax) and five (90–100 per cent of HRmax) you’re in the high intensity zone and no longer in “slow training” mode.
So, what is the right zone for slow training?
“Zone two is ideal for slow training. Whereas zone one is generally considered a warm up, zone two should feel relatively easy – where you can maintain a low heart rate and hold a conversation. It’s the foundation of cardiovascular fitness,” explains Dr Laukkanen.
If zone training sounds a bit fussy, a simpler way to make sure your training is slow enough is to follow an equation known as the MAF method, and keep your heart rate below that. “Fitness coach Phil Maffetone pioneered the concept of low heart rate training as a way of improving aerobic fitness without risk of overtraining – it is a popular approach with runners, cyclists and triathletes,” explains Dr Laukkanen. “Maffetone’s formula is 180 minus your age. The idea is that by consistently training at a low heart rate, in time, you will become faster without having to push your heart or body too hard.”
If you don’t have a heart rate monitor or watch, you can use the “talk test” instead. You should be able to hold a conversation easily during your slower workouts and feel energised throughout – the training should feel too easy. “When I am done with these workouts, I feel like I could do more. I never feel defeated,” says Eden. “This slow training helps me keep good form and ensure I’m able to control and practice my breathing. It also helps me avoid injury.”
How many of your workouts should be slow sessions?
Almost all of your training should be at a low intensity when training for a race, with most athletes following an 80/20 split. “This refers to spending 80 per cent of your training at a lower intensity, and 20 per cent at a higher intensity,” says Eden. “This balance is extremely crucial, because it allows the body to build endurance without overstraining.” If you’re training five times a week, only one session should be a high intensity or speed session, with the rest in zones one to three. “Which is a big test of discipline,” says Eden. “We look at discipline as showing up and doing hard things, whereas in this training experience, there is a lot of implementing discipline to actually hold back when the pace feels too easy. You just have to trust the process.”
There’s other benefits to training slowly too
When you’re not going full pelt, “there’s time to adapt and strengthen the tendons, ligaments, joints and bones,” explains Eden. “They adapt to the consistent stress and load gradually, which actually leads to fewer injuries. Training slowly means having a chance to recover and also reduces DOMS – or delayed onset muscle soreness – giving you the opportunity to focus on technique and form. This leads to long term efficiency and way less stress and energy wastage.”
