Our guinea pig takes it to the limit in the name of science

It doesn’t hurt THAT badly. Getting a metabolic assessment where you cycle to your max with a weird mask strapped to your face is never going to be particularly pleasant, but I’ve known worse. Sure, you’re in pain, but it’s only really bad for a matter of seconds and, unlike an interval training session, you don’t have to start again after a little break. Just tell yourself that it’s all for the greater good and it’s fine. Well, ‘fine’ might be pushing it. It’s bearable.


I’m visiting Peter Byworth of Metabolic Solutions at Le Beau Velo, a high-end bike shop in Shoreditch, London (the same place that I went to for a bike fit for a Viner recently). Peter comes here every few weeks to work with members of the public and I’ve volunteered to be the road.cc guinea pig.

The aim is to measure my body’s metabolic response to exercise so that I can get the best results from my training time when I go away from here. Make sense? In a nutshell, Peter is going to give me the data I need to train most effectively.

“Most of my clients want to know, based on the time they have available, their aims, and the metabolic data we provide, what’s the best way they can use their training time,” says Peter. “That’s the service we provide. They walk away with something that informs the way they should train for the next few months.

“Guessing is not an intelligent choice if there is a better alternative available. Trial and error is not a sensible strategy if time is of the essence.” That’s Peter’s mantra. He’s going to give me some advice based on good, solid science.

I want to maximize my performance on the bike – I want to ride as fast as possible – but other people might be more interested in losing fat. Whatever your goals, the procedure is the same. You get on the static bike and you pedal at your preferred cadence while Peter gradually increases the resistance. Runners can use a treadmill; any equipment with progressive resistance will do.

“You’re doing well. Looking strong. We’re going up a level…”

We go up a level. We go up quite a lot of levels. I keep going until my legs burn, my throat is rasping and I can’t pedal anymore. Then Peter yells more words of encouragement and I discover that I can pedal some more after all, so I dig deeper for a few seconds giving it all I’ve got… I’m chucking thunderbolts and lightning and everything else I can find at the pedals. And then it’s over and I feel a bit sick. It’s tough but the whole physical part of the assessment takes less than 15mins.

All the while I’m wearing a heart rate monitor strap around my chest and a neoprene mask that’s hooked up to a gas exchange analyser. Heart rate monitor: fine, most of us are familiar with them. Neoprene mask: not so much unless we’re MPs. Gas exchange analyzer: there aren’t too many of those about. It’s a technical piece of kit – in that I haven’t got a clue what goes on in there. But the important thing is that it measures the amount of oxygen you are using and the amount of carbon dioxide you are exhaling and sends it all to a computer that records and analyses the measurements.

The bike is also measuring the power you’re putting out. So, once you’ve finished, Peter can tell you what your body is doing at any given heart rate and wattage, and explain how best to train in order to achieve the results you’re after. You can go away and use your own heart rate monitor and power meter, if you have one, to train at the most useful intensity for the ride you’re doing. Clever, eh?

You’re talking about £145 for the metabolic assessment, though – less, admittedly, if you buy in bulk. Why not just wing it when it comes to training? Buy a heart rate monitor, get some training zones off the internet, and surely you’ll be there or thereabouts?

“Lots of people will spend their money on a heart rate monitor but they don’t really understand what the information means,” says Peter. “How much is it actually informing their training? They might have some idea of their maximum heart rate, the sort of number they might see when they start training or hit the red zone, but over and above that they’re not really getting much out of it.”

Sound familiar? A common way of training might be to use the good old 220 minus your age rule to give your maximum heart rate (in beats per minute or bpm), and then work out training bands based on a percentage of that. The trouble is, that’s often miles off – both the maximum figure and the bands. My theoretical maximum is currently about 12 beats out; it has been even further away in the past. Peter reckons he often sees people who have been training at completely the wrong level to achieve their goals.

“Overestimation is one of the strongest reasons for getting yourself objectively metabolically assessed,” he says. “People often overestimate what exercise intensity is appropriate for their long, slow distance training – their base-type work. They’ll be working at intensities where a good deal of carbs are being chewed up when they need to work at a lower level, at least initially. The other thing is that people will often overestimate where their lactate threshold is.”

Your lactate threshold is the exercise intensity at which your body can’t process blood lactate as fast as it is being produced, so it starts to accumulate. There’s a lot of debate in sports science about the precise role of lactate during exercise – let’s not get into that right now. What’s important here is that if you exercise beyond your lactate threshold, sooner or later you will need to reduce your pace/workload because with accumulating blood lactate levels, your body's ability to sustain a set workload is increasingly compromised over time.

“More experienced athletes often think they know where their lactate threshold is based on sensation,” says Peter. “But what I tend to find is that it’s often 8-10 beats lower than they think.

“What I believe is happening is a sensational lag time between a client’s physiology as picked up through the gas exchange analyzer, and when they consciously clock the sensation. The lactate threshold is the point of equilibrium. By the time they start to feel lactate accumulating, they’ve been exercising beyond that point for a little while.”

That’s a problem if someone works out their race pace based on the heart rate they think corresponds to their lactate threshold. If they’ve overestimated the heart rate, the lactate level could gradually creep up and their fuelling strategy could be completely out. You might get away with that in a short race, but in an eight-hour sportive, for example, it’ll all go horribly wrong at some point. It’ll get ugly, probably at the bottom of the biggest climb on the course.

On the other hand, Peter also sees people who fail to make the most of their training time by underestimating what they’re doing.

“I’ll see people who haven’t had the confidence to push themselves hard enough in training and racing. I give them the physiological data they need to increase the intensity and make themselves a much better athlete.

“The point is, there’s a whole lot of psychological stuff that can have a bearing on your training when it really shouldn’t. If you have clinical-grade, accurate, impartial information that’s delivered by someone who has expertise and experience in the field, that’s powerful.”

Peter, who has tested thousands of clients over the past decade, sees lots of people whose training has gravitated towards a middle ground.

“It’s often not structured enough or of a high enough intensity to give the benefit of speed and strength work, and it’s too high to be long, slow distance type training. It’s better than nothing but it’s a long way off optimal training.

“When people have a metabolic assessment, we set the parameters upon which their training should be based in order to achieve their objectives. And people go away with a revitalized appetite for their training regime and racing.

“Hopefully, that’s partly because I deliver everything with passion, but also because they go away with more knowledge and buy into their training much more. Each training session isn’t just another session; it’s a particular session with a specific aim, and that gives your training much more colour.

So, what is this information? You get your VO2 max – the total amount of oxygen you are consuming, in millilitres a minute, divided by your weight in kgs – the amount of air circulating through your lungs in litres per minute, the amount of carbohydrate you are using in Kcal per minute as your heart rate increases, and a similar figure for fat use.

But the most practical data you get are the training bands you need to achieve specific goals. These are:

• Recovery: the intensity to train at for active recovery

• Zone 1: Optimum fat usage

• Zone 2: Endurance

• Zone 3: Tempo

• Zone 4: Threshold

• Zone 5: Anaerobic fitness

If none of these bands makes any sense to you, don’t worry, it’s all explained. If you’re new to training, fine, you’ll get a layman’s explanation. If you’ve got more experience, you can get a more in-depth explanation of your results. No matter what, you’ll leave knowing what you need to do to move your fitness forward. You’ll know at what level to do you base work, your threshold work and so on. As well as your heart rate bands, you’ll get your bands for training by power too.

“Heart rate data – your response data – becomes really useful when you overlay it with a veneer of absolute source data like watts, time or distance. Those are absolutes. 300W is 300W. Some absolute data and some response data – heart rate – gives you a three dimensional picture of what’s going on. It tells you what your output is and how much it is costing you today.

“If you use a power meter on its own, it might tell you that you’re pushing 300W, but how are you feeling at 300W? If you’re usually doing it at a heart rate of 155 and today you’re doing it at 165, something is wrong. So, your heart rate data is a response to something else that’s going on, and that’s its value.”

If you like, that’s job done. You can clear off home, wait for your stats to show up in your in-box, and adjust your training accordingly. But you might want to see this as an on-going process.

“Metabolism is dynamic,” says Peter. “It’s not like measuring the length of someone’s femur. Your metabolism is adapting all the time. The key question is whether you’re affecting it in the right way.

“The initial assessment sets the parameters upon which your training can be based to begin with, but the extent to which it is successful is the extent to which those parameters are moved. Once we know where your lactate threshold is, the idea is to push it up. If your zone 1 and zone 2 are low at the moment, the object is to get them higher so you can be even more fat efficient.”

One other thing that’s worth mentioning is that if you sign up for two tests up front, you get the option of a 12-week interactive programme from Metabolic Solutions. They’ll send you a questionnaire to find out about your aims, how much training time you have, how that’s split up through the week and so on. Using that alongside the metabolic profile information, they’ll produce a bespoke programme for you in three four-week blocks, feedback at the end of each block getting absorbed into the next one. If you want them to get you to the start line of a big race in three months’ time in the best condition possible, they’ll produce your training programme. It’s another option if you want it.

Peter advises a retest after 3-6 months, depending on how much training time any client has. Someone who trains more might come back towards the start of that period, someone who trains less towards the end. After that second assessment, you might want regular testing twice a year. He would, of course, advise frequent testing; he clearly believes strongly in the benefits and it is, after all, his business. That all costs money, naturally, and you have to decide for yourself whether it makes sense for you. But if you’ve never given it a go, maybe you should; it might be just the boost your training needs.

For more info on Metabolic Solutions go to www.metabolicsolutions.co.uk or call 020 3287 3745.


Mat has worked for loads of bike magazines over the past 20 years, and been editor of 220 Triathlon and Cycling Plus. He's been road.cc technical editor for seven years, testing bikes, fettling the latest kit, and trying out the most up-to-the-minute clothing. We send him off around the world to get all the news from launches and shows too. He has won his category in Ironman UK 70.3 and finished on the podium in both marathons he has run. Mat is a youthful 45-year-old Cambridge graduate who did a post-grad in magazine journalism, and he is a past winner of the Cycling Media Award for Specialist Online Writer.


TheHatter [770 posts] 4 years ago

I'm reading the Cavendish bio at the moment. He is far from complimentary about these tests and sports scientists generally. Horses for courses I guess.

Alan Tullett [1566 posts] 4 years ago

Perhaps if he paid more attention to it he might do a bit better in the mountain stages!! This year's Giro isn't going to suit him one bit. Already taken him out of my fantasy team even though I'm a great admirer.

Ciaran Patrick [116 posts] 4 years ago

As a sports performance and fitness among other things I am constantly amazed at how people who come to me will no feeling for how they train. I use the term 'feeling' not in an emotional sense but in away that when you train, you don't just train for performance you also at the same time learn to understand your body and how it reacts and 'feels' in a variety of ways. The cult of 'lets hammer to the max' offers no refinement for what is actually is needed. You hear a lot about the psychology of racing but not very often the term 'psychology of training'. The point I am making is if you intend on getting VO2, lactic threshold or HR max tests what ever. You should maybe consider first how do I train. How can I improve performance. I would suggest firstly looking at how I train and I bet most of you have no idea how to really approach this complicated subject. The question is how do I spend my £290 best. I could get tested and have a programme done or a cheaper way could be to have a chat with a coach about how you train or you could try and work it out yourself. Testing can help but there is more to it than that. - have a think and be brutally honest in regards what you actually know about how your body, how you train and all the links and associations that go with it.

Argy [138 posts] 4 years ago

Ciaran Patrick, cracking post mate! you make some very good points!  39

GerardR [117 posts] 4 years ago

The horribly expensive solution is to buy a power meter, which is what I chose to do in preference to buying a nice new carbon + Ultegra bike. At 53, I felt I needed to train smarter, not necessarily just try to go harder. This sort of testing seems a practical, more affordable alternative.

Making sense of the data is a long process, but most of what is being said here illustrates the need to know how you body is performing and now best to train.

I think that the SRM has been a more valuable investment than a "better" bike, as technology is seductive while power:weight ratios and other SRM data are more like a cold shower. Riding here in New Zealand is also like a cold shower at present, so make the most of your summer.