Hi, I'm preparing for a two-week self-supported ski tour across Baffin Island later this year or more likely next year if covid-19 travel restrictions aren't lifted. I've previous back-country wilderness experience in Europe and Scandinavia. Twice a week I drag a car tire around a local park here in London, much to the amusement and curiosity of joggers and dog-walkers. This exercise mimics to some degree the challenge of skiing across ice and snow while pulling a sled. The tire weighs 13kg (29lb) and I add weights, currently 5kg (11lb). The surfaces are primarily paved and maximum inclines are around 10%. Using a GPS device I complete around 10km (6 miles) with an elevation gain of around 200m (660ft) on average on each two hour training exercise.
There's a lot on the web about the setup for tire dragging but perhaps not surprisingly little on training programs using tire dragging in preparation for an expedition. I'm interested in any tips and advice. One metric I want to track is energy used (kilojoules) but I can't figure out a way to calculate this!
Any help is much appreciated!
Thanks for reaching out!
That sounds like quite the trip you have planned! When I was living in Fairbanks, Alaska I had the great honor of helping support (with the logistics of storing gear for the expedition) Andrew Lock's two attempts to ski across the Brook's Range with Neil Ward. I remember talking with him about his training regime and it sounded very familiar to what you are doing. Good on you!
In terms of calculating 'kilojoules' I am assuming you mean calories burned (likely what we refer to it as here in the states). Is that what you're looking for? How much energy you are burning during your workouts? We have some fitness watches (and there are even some rough calculations you can find on the internet, depending on how accurate you want them to be) that calculate calories burned by using your heart rate and personal information such as height and weight. Please let us know if that is the kind of information you are looking for or if it is something else.
Thank you for sending us an email! We're going to post it here in the community so other folks can read it and potentially weigh in:
Thanks for responding to my post. Much appreciated.
Yes, we’re talking about calories as a measure of energy burned during a workout. The underlying objective is to assess the approximate daily calorie intake I need pulling a sled for 20-25km a day. Excluding rest stops, this works out at around 5 hours/day pulling (5km/hr or 3mph/hr). I should stress that there are so many variables - body weight, pack and ski weight, sled weight and friction resistance, distance, ascent, descent, speed, terrain difficulty, temperature and altitude to name a few – that a rule of thumb of 10,000kj per day (500g of food averaging 2,000kj/100gm) plus extra energy bars is probably the wisest approach! It’s not as though there’ll be a convenience store on route to top up supplies!
So, to come back to the objective and a method to make a pre-assessment of the energy requirement based on the closest activity to mimic pulling a sled, namely tyre pulling. If I was attempting the expedition on a fat bike I could calculate energy expenditure quite accurately using a pedal power meter. At the other end of the scale, if there’s no exertion-related data available from my body, my gps device is left to calculate energy expenditure based on the raw metrics including time, distance, age, weight, and activity level. Since this method doesn’t take into consideration my effort level ascending or descending, headwind or tailwind, etc, the number of calories burned is only generic.
That brings me to your suggestion – heart rate. According to the sports coaches and nutritionists, most of the HR-based calculations are within 10-20% accuracy. Some of the algorithms used in HR devices are very sophisticated. The more advanced methods evaluate beat to beat to estimate MET (Metabolic Equivalent) which is used to determine actual work expenditure. Some devices apparently have a learn function that with continued use tracks changes in fitness and adjusts the energy algorithm.
Wearing a strap around my chest while pulling a sled up and down paths in my local park seems to be a reliable method to measure calories expended even with the HR calculation algorithm being ± 10-20% accurate based on comparisons performed by cyclists using HR data and power meters. Even so I may still rely on a rule of thumb!
All the best, Robert
@REI-JohnJ pointed me towards your post. Happy to provide a few thoughts. As he mentioned, I did a number of mid winter sled hauling trips in the Alaskan arctic.
I didn't ever measure my calorific consumption while training for the trips but like you, I hauled sleds on hilly bitumen roads for several hours a day in the months leading up to the trip. In addition to developing stamina, I was trying very hard to strengthen the ligaments in and around my knees as i felt that they were my weakest point after many years of heavy load carrying in the Himalaya. I started out with a 4 wheel drive tyre on dirt tracks but quickly changed to bitumen to get the necessary resistance. I then moved up to a truck tyre to get sufficient weight.
Our food consumption was designed to fuel us for both the cold and energy expenditure. Calculations were based on data provided by Antarctic adventurers and some military research. It's worth noting several key points. Firstly, we were pulling heavier sleds than you are likely to have, given that we were out for several months. We were being resupplied every few weeks but the amount of fuel and the weight of sleeping equipment necessary for constant -40C and frequently colder temps, was extraordinary. About twice what I'd normally use on a Himalayan mountaineering expedition. Secondly, it takes several weeks for one's metabolism to kick into gear to enable you to consume the calories that you actually need. So calculations for long expeditions like ours worked on what we could ingest for the first couple of weeks, then increased about 10% for next two weeks, then increased another 10% and so on, until it was about 130% of the original allowance. We had to do it that way because at the start we simply couldn't consume the amount of calories that our bodies would demand when our metabolism caught up. On a short trip like yours, you'll be able to stay on the same lighter calorie intake for the duration of the two weeks. Indeed you could probably go quite light on the food and just lose weight.
We calculated a need for 6000 calories per person per day (yes calories not kilojules) at the start. That eventually built up to 7500 calories per person per day. As yours is only a 2 week trip in what i assume will be warmer conditions than the arctic winter we had, your demands should be less. Our food consisted of high energy, high fat, high protein items and we allowed 1kg of food per person per day. Brekky - oats, butter (or olive oil), milk powder. Snacks through the day - nuts, probar meals, chocolate, cheese, dried meat. Dinner - 2 to 3 serves of freeze dried. Most fats were consumed at night when best digested.
Hope that's helpful. Happy to provide more info if desired.
Just have to chime in here. My only experience pulling a sled on skis was the Muldrow Glacier route on Denali in 1987. I trained by running and cycling - at least one long session each week. Had no problem with the sled and we were also carrying 40 pound or so packs. Had plenty of food and ate heartily. Temps were typically -20F during the day and we had one storm event with wind chill enhanced -80F (coldest I have ever experienced).
Probably helps to be just a tad overweight when beginning your trip. Take plenty of food. Congratulations and let us know how it turns out!!
Hey Hikemor, Have to laugh - I was on Denali in 1987 too. Up the West Rib, down the buttress. Might have shared a beer with you in Talkeetna! cheers
I was there in June (the warm season - comparatively speaking). I was a volunteer member of the NPS patrol and did not advance very far beyond the Advance Base Camp - was there for about two weeks until HQ pulled us out. Our team leader was Ralph Moore, then a climbing ranger at Denali. When I last knew, he was Superintendent at Gates of the Arctic.
We had planned a summit day, doing it all from ABC (we were acclimated by then)but would up treating a serious HAPE case. Our efforts were monitored by Dr. James Wilkerson (Medicine for Mountaineering) and that was a very nice alternative. Had a worthwhile critique afterward.
The irony was that I was full time staff at Channel Islands NP at the time, and I took 30 days leave to got to Alaska and volunteer for the patrol. But it was a totally wonderful experience and NPS provided a lot of specialized gear. Quite a contrast with most climbs in the desert Southwest, where glaciers are rare.
Were you on the hill when I was there? There were lots of folks at ABC, and many didn't get a whole lot further. 1987 was a record year for the lowest percentage of successful climbs - just recently surpassed. Small world, isn't it?