How to enjoy doing Cardio that is good for you!

There are three types of people:

1. The genetically gifted - Those that are good at being cardiovascular fit and prioritise and enjoy that type of exercise over everything else.

2. The masochists - Those that suffer cardiovascular training and do it because they know it is meant to be good for them.

3. The ostriches - The majority who know that it’s good for them but avoid cardiovascular training at all costs. As it’s too difficult, uncomfortable or embarrassing to do.

The common image of cardiovascular training is going for a run, thrashing away on a rowing machine or attending an exercise class where the instructor does such intense exercises you want to faint. If you don’t go to a gym it could be doing a home HIIT workout or a Peloton cycle session in the privacy of your own home.

They are all characterised by being out of breathe, sweaty and fatigued muscles. For those that do it and get better they also know they have to keep doing it consistently to maintain and build fitness, which means it has to be part of their lifestyle.

But it does have the best chance of improving your longevity

Both the UK and US public health agencies recommend adults do at least 150 minutes of cardiovascular activity per week. They don’t define the intensity or type of activity, they are just happy if you do the 150 minutes.

This is underpinned by research that identified that people in the bottom quartile of VO2 max (measure of cardiovascular fitness) are nearly four times likelier to die earlier than expected, than someone in the top quartile. A person with moderate fitness in the mid range of VO2max still has double the risk of a top quartile person, but being moderately fit does reduce your risk of dying early by 50%!*

This post is for the masochists and the ostriches because I’m about to set out a style of cardiovascular training that is the most time efficient, easiest to do with the least risk of injury and least time to recover from. Plus the fitness benefits can be sustained, even when you miss a few sessions.

30 years ago it was called steady state cardio and now the longevity evangelists refer to it as Zone 2 Cardio.

How does Zone 2 Cardio work?

The human body relies on three main energy systems to provide the energy needed for various physical activities. For most people, the first two are what they associate with doing “cardio” - out of breathe, burning muscles and hitting that point where you can’t move any more.

These energy systems are:

Phosphagen System (Immediate Energy System):

Provides energy for short, intense bursts of activity lasting a few seconds (e.g. a single maximal-effort lift or a sprint). It is an anaerobic process that does not require oxygen and provides energy quickly but has limited energy storage capacity, sustaining effort over a few seconds.

Glycolytic Anaerobic Lactic System:

Provides energy for activities of moderate to high intensity lasting from about 30 seconds to a few minutes (e.g. a 400-meter sprint or weightlifting). It is an anaerobic process breaking down glucose without oxygen to create energy, resulting in lactate acid as a by product, which causes fatigue and that burning sensation in your muscles.

Oxidative Aerobic System:

Provides energy for activities of low to moderate intensity lasting for an extended period (e.g. long-distance running, cycling, or endurance activities). Uses oxygen to convert carbohydrates, fats, and, to a lesser extent, proteins into energy to power muscle cells.

It is a slower rate of energy conversion, so if activity intensity increases quickly the Glycolytic Anaerobic Lactic System kicks in like a turbo charger to provide additional energy required to keep going.

Zone 2 training uses only the Oxidative Aerobic Energy System which is around your 65-75% Heart Rate Max range. Your Heart Rate Max is calculated by subtracting your age from 220. You then set heart rate zones based on the percentage of that max number (there are more sophisticated heart rate range calculations but for the purposes of this post I’m using the simplest one). The Zone 2 name comes from the grading system used with heart rate monitors to categorise intensity of exercise.

Or more easy to understand and gauge, where you can talk while exercising but you are breathing heavily.

When intensity increases and not enough oxygen can be consumed the body switches to the Glycolytic Anaerobic Lactic Energy System that create a by product of lactate acid and that is the point when you hate cardio.

The aim is to exercise within an intensity range that stimulates the Oxidative Aerobic Energy System but not at an intensity that triggers the Glycolytic Anaerobic Lactic Energy System.

Or said more simply you only train at an intensity where your body gets enough oxygen to create the energy for the exercise you are doing. This means you don’t get out of breathe and don’t get the muscle burning and fatigue feeling that most people hate.

There are important longevity benefits of staying in Zone 2

• It stimulates the creation of new and more efficient mitochondria. These are the power houses of human cells that play a critical role in supplying energy. The more you have and more efficient they are, enables you to create more energy in cells and do more work. They naturally decline in volume and function as we age. Therefore Zone 2 training offsets ageing and builds a more efficient endurance base.

• The more mitochondria you have, the more glycogen can be stored in the cells rather than being stored as fat or in the blood which makes the body more efficient at storing and using food you consume and reduces insulin spikes. This will help you feel less tired during your working day as you have access to more easily available energy.

• Sustaining this endurance base is easier as it is retained for 14-22 days while the more high intensity training benefits created by the other two energy systems are only sustained for 2-8 days. Which means you don’t loose it if you miss a week or two. If you have a work life that may involve disruptions to your training, then you can focus on this type of training and not regress due to missed sessions.

To create the stimulation required to get these benefits, a Zone 2 training session needs to be at least 45 minutes and for optimal results, sessions need to generate 150 to 180 minutes of Zone 2 activity per week. Which means 3 to 4 sessions per week.

This may sound like a big commitment but due to the low intensity of the training, you can multi-task while doing it by watching TV, listening to an audio book/podcast or attending one of those town hall conference calls we all love.

What happens in practice

The reason for doing Zone 2 is compelling but how easy is it to do and what impact does it have?

Since May 2022 I have been trying Zone 2 training as part of my fitness programme. From that I can share:

• What actually happened in terms of fitness improvements?

• Is the frequency and volume prescribed achievable?

• What did I learn that could help you do it more successfully?

I plan each week to do three Zone 2 sessions, using a Concept 2 Erg indoor bike. The session are 45-60 minutes long, aiming to be in Zone 2 heart rate ranges for about 40-55 minutes.

The graph below shows the fitness improvement from an untrained low fitness base to the last five months. The graph shows distance travelled on average per session per month given a fixed training time and heart rate not exceeding the 75% Heart Rate Max range. This was my primary aerobic training, as my other sessions are focused on strength, stability and mobility.

When I started in May 2022, my VO2max was poor putting me in the low quartile. This was due to recovering from Myocarditis that damaged my heart muscle.

By the time I got to June 2023 my VO2max was in the mid range rated as good.

What actually happened in terms of fitness improvements?

The session time and heart rate level I could go to was fixed, therefore fitness improvement is measured by the additional distance travelled within those fixed parameters.

• 11% improvement in distance covered against the low fitness base

• 4% distance increase since June

• The improvement did tail off to 1% distance increase per month as I got fitter

If this was continued for 12 months it would increase work capacity by 3kms which would be a 25% improvement from the low fitness base.

What it also did was improve my Heart Rate Variability score. If you have a smart watch it calculates this daily and uses it to work out how well you can recover from physical and mental stress.

This improvement means my ability to recover from stress improved by 12%!

Is the frequency and volume prescribed achievable?

Getting to 150-180 minutes per week consistently is hard.

In July I had a virus that stopped me training for 2 weeks and in September I had to attend courses at weekends for 3 of the 4 weekends so missed sessions. With just 75 minutes average of Zone 2 per week in July, distance covered per session didn’t decline, so fitness was maintained.

The other months I did get close to the target of 150-180 minutes per week. However I’m in complete control of my schedule and can prioritise these sessions, which would be more difficult if you have busy work schedule.

Conclusion: Zone 2 training clearly works and improves cardiovascular fitness but once you get past the beginner gains you need consistent training volume over a long time to make big improvement steps in cardiovascular fitness.

The good news is when you get disruption to how many sessions you can do fitness is maintained. As long as you get back to training within 2 weeks you don’t lose the fitness you have gained.

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What did I learn that could help you do it more successfully?

1. Build up over time: If you are starting from a low fitness base start at 2 x 30 minutes a week and build up to 1 hour by adding 5-10 minutes per week. Then increase to 3 sessions when you can allocate time.

2. Indoor cycling works best:

   1. Low skill level as most people know how to ride a bike, rowing and running require more skills and technique to do well and avoid injury

   2. Low impact as weight bearing, good for people with knee or hip injuries

   3. No weather disruption

   4. Compact for home use

   5. Easy to regulate heart rate

3. Minimise travel time: Travelling to a gym to do Zone 2 takes time, so invest in a bike as part of your home office set up.

   

4. Make the experience comfortable with a few essential items:

• Avoid a numb bum by wearing cycling shorts.

• Use your smart watch e.g. Apple, Garmin, Fitbit to track your heart rate or invest in a Polar heart rate strap and track your heart rate more accurately on your phone using their App.

• Use the time to listen to a podcast, audiobook or music. You can watch your favourite show or sports event but you need to keep an eye on your heart rate to ensure you stay in the target zone.

• The bike can be a bit loud so a set of headphones that can handle getting sweaty helps.

5. Create a routine: Find a time of day and days in the week that you can allocate to do sessions and book them in your diary. You are looking to allocate 2-3 hours a week which should be 24 hours apart to help with recovery.

6. Take pride in being a tortoise: Keep motivated by tracking and being happy about how far you can go rather than how fast. The trick is to stick to the heart rate zones and not go too fast and build up the lactate acid that makes cardio sessions painful. If you can stay comfortable but still go further it is a great motivator to keep doing it.

If you had to invest in one thing to start to improve your cardiovascular fitness, I would recommend Zone 2 training. Creates a great endurance foundation, is easy to do and will probably help you live longer.

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* Reference study Kokkinos et al (2022) discussed in Outlive the science and art of longevity by Dr Peter Attia