Adventure Fitness: Body composition and how it affects your outdoor activities

By Joe Bonington April 22, 2021
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You don’t have to rock a set of six-pack abs to enjoy the outdoors but having a body composition that is optimised for your favourite activity will make sure you get the most out of every minute you’re out there.

I remember one day, sitting in a pub in the Blue Mountains after a weekend bushwalking. I was talking to a mate who shall remain nameless. I watched him as he ate a burger and chips, smashed his third schooner, talking relentlessly about how much difference his new ultra-light titanium mess kit made, and I looked quizzically at his portly figure and smiled to myself.

In this article I’m going to cover a gnarly subject: body composition and how it affects us in adventure sports and activities. I’ll explore what it isn’t – think fitness industry models and selfies – what it is and why it is important for general health. And most importantly, how it affects our adventures and activities. Or doesn’t, as the case maybe.

Body composition: What lies beneath

As a coach I really don’t care what you look like with your shirt off. I don’t care what you look like naked. I don’t care what you look like in your swimmers or at the beach. Or how you look in your undies in front of a mirror clutching your iPhone camera and preparing your latest Insta-famous post. Aesthetics is a totally subjective thing. The great thing is that most people in the adventure world aesthetics isn’t there primary goal either. 

Optimal body composition doesn’t mean you need a six-pack. ‘Looking good’ does not always mean you are at your most effective when tackling your favourite outdoor activity.

Yes, I know that we all have a deep rooted need to be attracted to potential partners, but we have other things to train for as well. Body composition as a term has been hijacked by the body transformation end of the fitness industry. It is now associated with bikini competitions, bodybuilding, Instagram fitness influencers, stripper heels and fake tan.

But the definition of composition is the nature of something’s ingredients or constituents; the way in which a whole or mixture is made up, NOT how it looks. So, body composition is (should be) the optimal composition of shape, muscle and fat of the body for the adventures and activities you want to partake in and goals you want to achieve. In other words, if optimal weight doesn’t include a six-pack set of abs, don’t worry about the six-pack. Spend your energy, mental space and focus elsewhere. We have finite resources, so use them wisely. 

The variance of need

On my books at present, I have trekkers, trail runners, mountaineers, paddlers, rock climbers, mountain bikers, skiers and two polar explorers, and the physiological needs of all are very different from each other.

They need very different levels of strength, endurance and lean mass. Add into the mix that some are going into very hot environments, and some are exposed to a lot of cold, you start to see that body composition requirements for each activity are very different. 

Before we go into specifics of some different sports though, we do need to look at some universal truths: there are some baseline conditions to consider. There does come a point with our weight – in particular with being overly fat – or at the other end of the scale underweight, or with a body fat level that is too low.  

A weighty activity

Now let’s start looking at our activities a bit more. If you are into mountain-based sports, one of the first things to consider about body mass is the extra energy that is expended carrying adipose tissue (in the form of visceral and subcutaneous fat) up and down hills every day, and the unnecessary impact it can have on the body.  

This affects us in several significant areas:
Weight on the joints – impact on the knees going downhill is significant. The more weight we carry, the more it affects the joints and when they do get sore the inflammation hangs around longer. 
If we are over the healthy weight range – we can use between 5 and 50% more oxygen exerting ourselves than someone within a healthy range. 

For example, mountain athletes such as mountaineers benefit from what is essentially a strong but lean and wiry frame, and a good solid muscle structure for carrying the load and for getting up mountains. However, any excessive size needs to be carried, and if you’re at altitude, using more oxygen than your wiry counterpart over the course of a day isn’t efficient and could lead to altitude mountain sickness (AMS). Then add to that the effect on joints of the extra load which is compounded by the extra inflammation caused by carrying extra weight. It means that the joints of someone overly fat will get sorer than the joints of the aforementioned lean person and be slower to recover, especially in oxygen thin environments. 

Now let’s look at mountain and trail runners, a lot of whom, too, have a slightly more muscled frame than their road running marathon counterpart. Please note, I did say slightly. A road-based marathon runner just needs to move forward on the flat, so being as light as possible is the go. Your mountain and trail runner is just as lean but tends to have just a touch more muscle structure, especially in the legs for coping with the hills, descents and technical trails. For those mountain and technical environments that they’re in, a stronger frame also copes with environmental issues such as tumbles and knocks and scrapes a bit better as well, which is more likely to happen in environments like the trails. More forgiving on the body fat side is trekking. Lean is good but a little extra body fat won’t go astray. 

And then at the other end of the spectrum we have the polar explorers. These are the anomaly in endurance based adventure. Pulling a 200 kilogram pulk (a pulk is a sled), you need to have mass. It’s basic physics. The more mass you have, the easier it is to pull heavier loads. But you’ve got to balance that with endurance because they might be having to cover the equivalent of a marathon every day as they’re crossing the snow in the Polar wastes. In endurance-based activities, the more mass you have, the more energy you expend. A polar explorer can lose as much as 30kg in one crossing. If they lose too much muscle it will weaken their ability to pull the pulk and contribute to fatigue slowing them down further.

Adventurers in the polar regions need to be sure to balance body fat (for warmth and energy expenditure) with muscular endurance for optimum performance.

They need a combination of strength endurance, endurance and general mass. The other thing they have to contend with is the cold. If they are running too lean, they will feel the cold more. Studies show that having more body fat reduces occurrence of hypothermia. So, your polar explorer is going to benefit from having solid muscle mass and a healthy layer of body fat.  

Training for this is a real challenge because the fitter you get the more efficient you get at burning fat and also you inevitably catabolise some muscle, so it’s this constant fight to get the balance right. 

The percentage factor

Please note in this body fat chart: Athletic doesn’t necessarily mean good, both from a health long term perspective or for your chosen activity. 

An example of this is that the body fat range for athletic females is 8-15% but below 12% body fat a woman is likely to go into a state of amenorrhea (loss of period, causing metabolic and hormonal changes which can affect things such as bone density and future ability to conceive). The term Athletic in this context refers to sports where low body fat is an advantage, such as trail running or climbing.

Body fat consists of essential body fat and storage fat. Essential body fat is present in the nerve tissues, bone marrow, and organs (all membranes), and we cannot lose this fat without compromising physiological function. Storage fat, on the other hand, represents an energy reserve that accumulates when excess energy is ingested and decreases when more energy is expended than consumed. Essential body fat is approximately 3% of body mass for men and 12% of body mass for women. Women are believed to have more essential body fat than men because of childbearing and hormonal functions. In general, the total body fat percentage (essential plus storage fat) is between 12% and 15% for young men and between 25% and 28% for young women. [Lohman, 1993 #4151, taken from Sport Nutrition 2nd Edition by Asker Jeukendrup & Michael Gleeson.]

The next step for optimum body composition

My recommendations are:
If you are a recreational runner/adventurer/ thru-hiker and mountaineer just stay within a healthy weight range: Men 11-20% women 16-30% body fat. If you haven’t got a six-pack don’t sweat it, there are a lot more important things to worry about.

If you are competitive at your activity or planning a big and really challenging trip, there’s two numbers you need to look at: 
1. Your body fat percentage – are you where you need to be? 
2. Your muscle quality – we call it your muscle number, which is the quality of your muscle and how dense it is. Is it good strong working muscle? With strong neuro-muscular connection, i.e., trained muscle or is it weak?

Eat appropriately for your training and train appropriately for your goals. And remember… If you do have a couple of kilograms to lose and you know it (like my friend in the Blue Mountains at the start of this piece), spend money on a good gym program or a nutrition plan rather than the latest piece of ultralight kit. It will be a better investment in the long term. Get the lightweight kit when you’re back in a healthy weight range!

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