I decided to write this article on ‘bonking’ because it’s affected me on two hikes over the past few years so I thought it was something worth sharing. As an Australian I need to clarify upfront that when I am talking about ‘Bonking’ I’m doing so from a perspective of an endurance sport and not as most Australians would understand the term relating to sex. With that cleared away let me explain what I mean. The term Bonking is mainly used in the US relating to endurance activities such as cycling and running but it is also commonly applied to long distance hiking and as such I am starting to hear Australian hikers use it more commonly. So what is it?
What it relates to is undertaking an endurance activity where you reach the point of sudden fatigue caused by the loss of energy due to the depletion of carbohydrate reserves. This is also known as ‘hitting the wall’; again another piece of jargon.
I’ve bonked/hit the wall three times in my life. The first was at a state athletics carnival as a teenager, and the other two times were doing long days of hiking, both over the past four years. In fact I wrote this article after the most recent time which was shortly before I wrote this article and even though I know what happened, I couldn’t believe I let it occur knowing better. Each time the process from start to finish has been the same, and also a bit of a surprise. In the case of the first time it wasn’t until after the fact that I realised what had happened but having been affected now I know what to look for and in theory at least I know how to prevent it.
As a generalisation the symptoms can vary but on a physical side you will generally feel extremely weak and tired. You may shake, sweat a lot, and feel dizzy or light-headed; you may also have heart palpitations. Extreme hunger may also be a symptom but not always.
The following is the pattern I have experienced each of the three times is affected me. On all three occasions it was during the hotter part of the year and always late in the morning around 11:00am-12:00pm. It comes in two stages:
When it hits me there really is only one thing I can do and that’s stop, rest and eat. I’ll usually find I need around 30-45 minutes after I’ve eaten something for my body to recover and start up again. Even then I’ll be looking for lunch to pack in as many calories as I can given I usually hit the wall just before lunch time.
My big issue is that because I lose appetite on long distance hikes, burning between 5,000-8,000 calories a day. I find that because I loose appetite on these sort of hikes I have to force myself to eat regularly. When I’m paying attention I will eat on an hourly basis, not huge amounts, but lots of calories. Typically I will have a decent breakfast packed with energy and consuming around 400-500 calories. I will then eat snacks throughout the day on an hourly basis eating roughly 150-200 calories per hour. I really do have to force myself to eat sometimes so its important to only carry food that you want rather than what you think you should carry!
I have also started to carry Clif Shot Bloks which are my preferred alternative to the gels often favoured by runners. I will usually consume a packet over two days and eat them in the afternoons. I find they give a quick hit of energy and are easy to consume when I don’t feel like eating. At the end of the day I finish off with a decent meal that includes a hit of protein as soon as I get to camp to allow my body to recover overnight.
This still leaves me with a calorie deficit and on a long distance hike and I have found over the years that I average losing 3.5 kg of body weight per week.
While I know what I need to eat on a regular basis, sometimes it’s easier said than done. For me its about eating something I really like so choosing food I enjoy, that is high in calories and provides plenty of energy is the key. It’s almost a bit counterintuitive when in our daily lives we need to think about watching our calories but on a long distance hike its open slather and the more calories the better. The main thing to remember is to eat high energy food on a regular basis to minimise the potential for bonking/hitting the wall.