Running magazines are regularly jam-packed with alluring promises and quick fix solutions: “Three key intervals for a faster you”, “Hammer these hill workouts to break your PBs”, “Top track sessions for improving your running”, and the list goes on.
These are great for selling magazines, and usually an entertaining read too, but what’s the scientific basis of these ideas?
I recently had the pleasure of attending a fascinating talk by Dr Dan Gordon, Principal Lecturer in Exercise Physiology at Anglia Ruskin University. Dr Gordon is a former Paralympic athlete and cyclist, still holding a track cycling world record; he has acted as consultant physiologist to the UKA Paralympic team, and consultant sports scientist to a variety of national-level squads.
Speaking to a group of athletes and coaches, Dr Gordon explained some of the science behind endurance training, and helped us to understand why several pervasive myths need rethinking.
These myths are worth exploring, because it makes a very practical difference to us, on a weekly basis, in terms of choosing the best training sessions to put our energy into.
In this article I’ve asked Dan Gordon to help us understand the subject of VO2 max, along with its implications for interval training, and what this means for us.
Myth #1: “High VO2 Max is Essential for Distance Running Success”
The term “VO2 max” is often talked about as the focus of training sessions. It’s also often the subject of those tempting promises in magazine articles for dramatic overnight improvements. Why?
VO2 max is the maximum volume (V for volume) of oxygen (O2 for oxygen) that you can take in and use for generating energy. Basically it measures your aerobic power. As your effort increases during exercise, the muscles need more oxygen. So the faster your body can convert oxygen from breathing into energy in the muscles, the more efficiently you can perform. But there is a point at which this reaches a peak: a maximum level of oxygen that your body can consume and use quickly enough. This is your VO2 max.
So, in principle, the higher your VO2 max, the faster you’ll be able to run.
There are various factors that determine VO2 max, including age and sex, as well as general fitness, but the most critical seems to be your genetic coding. A wealth of scientific data demonstrates that there are only limited ways in which athletes can actually increase their individual VO2 max.
As Dan Gordon says “blame your parents”.
Why Aerobic and Anaerobic Energy are More Relevant for Endurance Than VO2 Max
But despair not! Dan Gordon presents compelling reasons why the focus for endurance running should be different anyway. We do ourselves no favours by obsessing over VO2 max.
For endurance running, you don’t need to run as fast as you can. You’re not operating at, or indeed anywhere near to, your VO2 max. No-one can sprint for 26.2 miles, or for 10k.
Instead we need to understand how to be as efficient as possible with how we use oxygen. Dan Gordon explains:
“When we exercise we use energy from two sources, aerobic (with oxygen) and anaerobic (independent of oxygen). Aerobic energy is what is fundamental to endurance success but both energy systems work simultaneously, so if we are running sub-maximally aerobic energy predominates and anaerobic energy is relied upon less.”
“However we know that there is point, which occurs at different speeds for all runners, where anaerobic energy starts to predominate.”
OK, but what’s the problem with this?
“Think about what happens when your stride rate increases, the muscles now have to change length at a faster rate. For this to happen there has to be an increase in energy used to provide for each of these ‘muscle contractions’. The problem lies in that we also have two different types of muscle (fibre). Those that are aerobic (endurance) which are termed slow twitch, and those which are considered more anaerobic (fast twitch).”
“As speed increases the faster twitch fibres are engaged because they can generate more force than slow twitch and ‘contract’ at a faster rate. However for this to happen they rely on anaerobic energy. This process provides energy but also results in the production of lactic acid, which can be measured in the blood as blood lactate.”
The Lactate Turn-points
Dan Gordon uses various graphs with data from real athletes to show two critical points at which lactate production changes as athletes increase their pace. These are called lactate turn-points.
“At lower speeds, where the slower twitch (aerobic) muscles are predominant, there is very little increase in blood lactate. However as speed increases there is a gradual increase in blood lactate concentration as more fast twitch fibres are engaged. The point comes though when more fast twitch than slow twitch fibres are being used, and so the lactate concentration in the blood shoots up. It is this point that we refer to as the lactate turn-point or LT2.”
“There is also an earlier response which we refer to as LT1.
This is where there is a small but meaningful increase in the blood lactate concentration and so represents where the ‘threshold’ for anaerobic energy provision occurs. In other words, below this point there is almost no anaerobic energy contribution. A knowledge of these two key points allows us to understand the way in which our muscles adapt to training and also prescribe specific training zones.”
The point is that for improved endurance running, we want to delay LT1 and LT2 for as long as possible – in other words, to be going faster before they kick in.
Making a Difference
The good news is that LT1 and LT2 can be improved. With the right training, our bodies can become more efficient at using the oxygen available for longer; this means we can run for longer at a faster pace before lactate starts affecting us.
In fact, lactate turnpoints respond much more to training than does VO2 max. This is great news for endurance runners! This graph shows an example of how LT1 was improved in one athlete after training to improve their aerobic base.
So we can make improvements to our own endurance performance if we understand how to train ourselves to run with more oxygen efficiency.
How? Well let’s first explore Dan’s second big myth of endurance running…
Myth #2: “Interval Training is the Key to Endurance Success”
Distance runners often choose interval training as one of their key sessions: fast repetitions of short distances, such as track sessions of 6 x 800m or 10 x 600m.
But given that we’ve seen VO2 max is less important for endurance, this is perhaps not the best use of our time and energy.
As Dan Gordon explains, interval training is only going to be effective if you’ve already built an aerobic base. He shows that working on base training—long steady runs at a lower pace and intensity—is the most effective way to improve the lactate turnpoints and economy.
- Zone 1 (E for easy): Lower than LT1 is for recovery runs and also recovery between intervals.
- Zone 2 (S for steady): This is where there is a balance between O2 supply and demand, where the stroke volume of the heart is maximal and so we can do the long steady (aerobic base) training.
- Zone 3 (T for tempo): This is where there is an increase in lactate because we are now beyond LT2 but this is not so significant that fatigue sets in. This work can be maintained for around 40 minutes and enables us to develop an interval base and helps to shift LT2.
- Zone 4 (I for intervals): This is where the interval and faster speedwork training is undertaken, and training in this zone tends to be more focused on VO2 max. To be able to shift VO2 max at all, we need to train at VO2 max, and be there for more than three minutes (takes this long for O2 to reach a level point).
To understand where your own lactate turnpoints are, and your individual training zones based on those, you can take a blood lactate test, or VO2 test. These are widely available from various sports specialists, usually for a fee of up to £100. It might sound like a lot, but if it means you use your training time better then it could be a good investment.
So what does this mean for my training?
Dr Gordon is clear: there is no magic bullet.
If you’re training for distances of 10k and over, the key is to train at the right intensity, and predominantly this means developing an aerobic base through longer steady mileage.
If you focus on three key training sessions a week, those are probably best spent on long, steady mileage (zone 1) with a bit of threshold running (zone 2).
So does VO2 max matter at all? Should we still do intervals? There are various reasons for doing interval training: they’re great fun, they’re often sociable because they tend to be club sessions, they can give you a psychological boost, and of course they can make you quicker over a shorter distance.
We’re not necessarily suggesting that you should instantly drop these sessions. But if you’re seriously trying to train to improve a marathon time, for example, interval sessions may not merit a place as one of your three key sessions in a week. They will take up some of your energy reserve leaving you with less energy to put into the longer sessions, and making those a bit less effective.
The main point is to be aware of what’s happening in your body, and to understand how different sessions will help (or not).
And yes, be wary of those quick fix promises for miraculous overnight improvements!