Cutting through the Bullshit: Exercise Intensity

Training for endurance sport isn’t so complicated. We know it's working if race performance continues to improve without detrimental effect on short-to-long-term health. It’s as simple as that. However, we’re often hit with a overwhelming array of top-tips, ultimate training programmes and quasi-scientific terminology which hinders rather than helps our understanding of performance. 

In this article, I'll explore how bullshit (BS) hides such simplicity. Specifically, I'll focus on exercise intensity to show how simple it really is. Of course, I’d be failing as an expert if I didn’t at least attempt to sound at least a wee bit clever. 

As an accredited sports scientist, chartered scientist, academic and coach I’ve learnt to see the world from multiple perspectives. The fact that I love lots of different types of art photography and engage with how it is created adds another layer to my understanding of the world. These perspectives give me confidence that I know what I’m talking about.

 However, it makes me sad that I often feel that I’m floating in a quasi-scientific sea of BS information which is threatening to swamp the whole endurance sports world. This is a world in which a discourse of obfuscation has developed, circulated and consumed in such a way as to make most people believe that training is way more complicated than it is. It has taken me 25 years to develop sufficient wisdom to realise:

 a) that I was often guilty of adding to the level of BS, and 

b) what the philosophical basis of BS generation is.  

Such wisdom comes with benefits. Specifically it allows me to feel morally and intellectually superior to others. I rant at my long-suffering partner about how others don’t know what they’re talking about. These others usually include NGB’s, coaches, scientists, , well recognised authors and the writers of articles on websites.  The ire I direct at these purveyors of inexactitude is proportionate to their perceived status and ego.

BS is a more easily recognised, albeit vulgar word for inexactitude. It originates from the French word ‘bole’ meaning ‘fraud or deceit’. BS isn’t exactly lying, because many bullshitters are well intentioned. They simply don’t know what they don’t know or lack sufficient knowledge to rigorously justify why their beliefs are true. There are other bullshitters who construct their words superficially without adequate reference to the truth and/or present information in tediously prolonged ways that makes them and others believe they are clever. 

Many people have built careers on such BS, convincing others to adopt similar beliefs and practices as themselves.  It has a very important role in capitalism too, in which it is used to convince us to buy products and services that we don’t really need.  My own moral and intellectual superiority is misplaced because I have multiple pairs of trainers for different conditions, several GPS devices with advanced metrics software on them and a bike room as diverse as Imelda Marcos’ shoe rack.   

The most effective weapon against BS is intellectual rigour. Whilst we can’t know everything, we can question everything. Why does this work? What are the underpinning principals explaining why it does? What are the alternatives? How does it make me go faster or reduce the chance of injury? How does this training relate to helping me meet the demands of my chosen event(s)? What are the likely long-term consequences of adopting a specific practice? 

Regardless of whether you are a world-class athlete, coach or simply looking to break 23-mins for ParkRun, you should ask these questions to others and yourself. Over confidence, lots of technical jargon or lack of humility in responses appear as big warning dots on the BS radar. Exercise intensity is one area that is certainly appears regularly on my radar and is fundamental to our understanding of training. 

I get incredibly muddled when trying to interpret the language used to describe exercise intensity. Terms like VO2max, lactate threshold, lactate tolerance, threshold, fat-max, aerobic max, anaerobic work capacity, critical velocity and maximal lactate steady state are commonly used. It becomes confusing because ‘experts’ use similar terminology to describe different phenomena, and different terminology to describe very similar phenomena. Not all experts agree on the best way to measure or describe exercise intensity either.  There are multiple different ways to describe training zones and levels too. Consequently, coaches, athletes and sports writers often misinterpret the science, don’t understand underpinning principles or use scientific sounding language inappropriately. 

The end result is an excess sharing of BS in magazines, websites and dare I say it, NGB coaching qualifications. Thus, the BS perpetuates and everyone, including me, becomes muddled.

            Of course, as the writer here, I want to sound clever by presenting solutions. The first one is to talk about exercise intensity very simply in a way that an 8-year old would understand i.e. walking, jogging, running and sprinting. With new athletes I may talk of easy, moderate, hard and very-hard, providing further description such as what breathing should feel like or use a scale of 1-10. With more performance orientated types, I’d use race pace or actual pace descriptors such as marathon, 5km and 800m pace. For athletes I coach, I may use specific paces such as 3:35min-per-km using predicted race times or benchmark runs to calibrate these values.

            The second solution is more complicated. It means exploring the underpinning science of exercise intensity, training adaptations and human behaviour. Doing so is particularly difficult because science, textbooks and training manuals use reductionist and disciplinary approaches to explain complex phenomena. 

In my early career, I made the same mistake as many others by  adopting a ‘metabolic’ biased perspective on exercise intensity. This means only thinking about intensity and pace in terms of oxygen delivery to the working muscle, relative contributions from aerobic and anaerobic metabolism and their relationship with fatigue. Of course, delivery and use of metabolic energy at the working muscles are very important to exercise intensity regulation. But they’re only small part of the picture.

This picture looks dramatically different if we consider fatigue as an emotion, a complex set of feelings that influence how we think and/or act. These feelings come from how we sense internal (within the body) and external feedback. For example, we have chemoreceptors that can ‘sense’ the oxygenation (or lack of) of our blood,  we know how hard we are breathing and also sense environmental conditions such as heat, wind and gradient. These factors influence perception of effort. Cognitive processes are important on how we appraise these feelings. For example, I have a number of pet hates that affect my emotions in order:

Thus, I have to train my mind to deal with distracting emotions as they interfere with my pace regulation. Having a mentally tough day will subsequently make training feel harder than my power meter suggests too. Thus, fatigue and exercise regulation is a biopsychosocial phenomenon (i.e. it involves complex interactions between the body, mind and social factors). 

I argue that it should rarely be described  through numbers alone or  using wholly physiological terms. Doing so usually implies the use of BS and represents a misunderstanding of performance. However, I’m not one to ‘throw the baby out with the bathwater’. My understanding of exercise intensity and fatigue is still underpinned by physiological principles that are well summarised by a paper by Mark Burnley and Andy Jones on Oxygen Uptake Kinetics. It took me years to get to grips with the principles underpinning this topic but I’ll try to summarise in a few paragraphs.

The use of training zones to control exercise intensity is based on the assumption that energy turnover is directly proportional to pace and that changes in oxygen uptake in relation to changes in pace are instantaneous. This is not the case. Rather, by examining the temporal response of oxygen delivery to the working muscles, we can:

“  determine the instantaneous rate of aerobic and anaerobic energy transfer, the mixture and amount of substrate used, and the tolerable duration of the exercise”.

In other words, the VO2 kinetic response tells us lots i.e. how efficient/economical an athlete is, whether carbs or fat is the predominant fuel source and a bit about how quickly an athlete is likely to fatigue within specific exercise intensity domains. With a bit of extrapolation, we can make inferences on muscle fibre composition and lots of other things too. In short, it tells us about some of the ‘why’s’ of performance. More practically, intensity domains are described by words everyone can understand without going into the metabolic details:

As a coach, these domains underpin how I think about training prescription but with only one question in mind: how will training make someone go faster? I’m not thinking how a workout will increase VO2max, improve running economy or pace at lactate threshold. Rarely will I describe a workout using specific physiological terms, unless a) physiological parameters have been measured directly, and b) using physiological descriptors will enhance an athlete’s understanding of why I am asking them to do something.

For us to talk about the purpose of a training workout in metabolic terms typically suggests a lack of appreciation of the complexity of training adaptation processes. These processes operate across molecular, cellular, tissue and multiple organs including cognitive processes within the brain. Even the very finest minds in integrative physiology have not come close to understanding the complex links between human mind, muscle and fatigue in a laboratory environment, let alone a messy ‘real-world’ one.  Rather, the application of science to endurance sport has (understandably) focused on the things that are easiest to measure i.e. oxygen uptake and blood lactate. 

I am certainly not arguing that these things are unimportant to training. Rather, I’m suggesting that how they have shaped the wider discourse around exercise intensity and training prescription has gone way beyond the bounds of the scientific evidence and are thus creating illusions of validity. The scientific evidence typically emanates from carefully controlled laboratory environments and is rarely validated in messy ‘real-world’ environments. What we think, how we perceive intensity and how we act is influenced by many different factors. Things like the weather, road gradient, menstrual cycle and what our day at work has been like affect our feelings, our performance  and how we adapt physiologically to training.

Furthermore, there are four implicit assumptions when using exercise intensity training zones: 

1) That a relatively constant pace is maintained throughout the workout

2) The energy requirement for an given intensity is met instantaneously

3) That economy/efficiency (the energy turnover for a given pace) remains constant over time, and  

4) Specific training adaptions, particularly relating to aerobic and anaerobic systems, are independent and specific to particular training zones.

However, ‘real world’ observations and the study of VO2 kinetics,  tells us that none of these assumptions are valid. Despite this fact, most training manuals, including those used to educate coaches about exercise intensity, present  ‘scientifically’ constructed training zones that are based on these assumptions being true. Furthermore, specific workouts are usually described in terms of the energy systems engaged i.e. aerobic or anaerobic. What studying VO2 kinetic responses tells us is that both these energy systems are always ‘switched on’ and in a state of flux, particularly in interval and variable intensity type workouts. Additionally, there are marked individual differences in VO2 kinetic responses and training adaptations within different exercise domains which are influenced by factors such as training status, prior exercise, muscle fibre composition and fatigue. Thus training effects, fatigue and recovery will be very different between individuals. I therefore argue that it is not overly important to adhere strictly to training zones or levels as long as intensity is broadly consistent with the aims of the workout.

Asking ‘how does the workout goal relate to the performance demands of my event?’ and  ‘what are my senses telling me about the intensity I’m at?’ is the priority. More important than adhering to ‘scientific training methods’ is to learn to listen to your body and act appropriately. Of course, there is a need to override these signals, particularly in the final third of a race, and such a skill can be learnt in training.

But what do all my musings mean to you? My hope is that they’ve helped develop your BS filter just a little. Key take home messages are:

Be cautious when engaging with any training concepts that are primarily based on physiology or are overly reliant on physiological terminology. The purpose of training is to improve, and the adaptations required to do so involve psychological and social factors too.

The brain is far more powerful than any metric presented on a training device such as a GPS. Learning to ‘perceive’ effort in relation to different exercise intensity domains allows you to moderate intensity based on how you feel. By all means, use a GPS to record your efforts or to do a quick check on your pacing. But do not be dictated to by the technology you use as this will limit performance.

Avoid describing training using physiological sounding words such as VO2max or lactate threshold. I advocate describing a workout in terms of what it means to the demands of targeted events i.e. your race distance pace and use language to describe intensity that an 8-year old would understand.

Don’t worry too much about training zones. There’s no ‘best’ training zones system or ‘best’ way to train. A programme that includes easy, steady, race-pace, interval and fartlek efforts will typically work if you get the ‘doses’ right. That means listening to your body when it is fatigued and pushing on when you feel great.

My final take home message is to suggest not putting too much weight into what those who advocate overly scientific approaches or dismiss science as irrelevant. They are likely to be purveyors of BS. There is a continuum of beliefs on the usefulness of science, particularly physiology in endurance sport. Some people believe scientific approaches to training prescription are superior to more traditional ‘craft’ trial-and-error approaches. There are others who believe scientific approaches to represent BS. Whilst there are degrees of truth at both extremes, I prefer to be more pragmatic. Engaging with and understanding the science allows me to justify what I consider to be BS and why. Practical experience, bound in a deep understanding of the complex biopsychosocial nature of performance tells me that health, wellbeing and performance  should be the focus of every training programme.