Flat vs. Hilly Course
I will be doing my 19th Birkie in a few weeks.
My average time (classical) for the 54 km's is 5 hours and 45 minutes, hence, for me, it is an "event", not a race.
This past Saturday, I participated in the little known, Muskoka Loppet, near Huntsville, Ontario (about 3 hours north of Toronto). I skied 30 km's in 3 hours and 6 minutes. The course is unusually flat, in contrast to the Birkie.
I am curious about energy output on a relatively flat course as compared to a hilly course. Are there any "equations" which support a 30 km "flat" course requires more energy than 30 km's of the hilly Birkie course (let's say from the 15km to the 45km mark). Or is 30km's, 30km's (irrespective of terrain), like a pound of feathers is as heavy as a pound of metal?
I'm thinking the 30km's on a flat course is tougher than a hilly 30km course (with good choice of wax for both courses). Perhaps my legs are stronger than my arms and the 30km flat course requires much more arm involvement than a hilly course.
All the best,
This is a pretty complex question and to answer it thoroughly requires a technical, neuromuscular and physiological analysis. Technical economy, or the amount of oxygen used to produce energy at a given grade and speed, is one of the big determinants of overall energy cost. The strength of the specific muscles, their ability to produce power over long distances and their resistance to fatigue is also an important consideration. Finally, the Maximum Oxygen Uptake, VO2max, along with percentage of maximal oxygen uptake that one can sustain for the distance of the race is perhaps the most important determinant. Those with better economy and/or a higher VO2max will be able to produce power more efficiently and ski faster over long durations and at a lower energy cost.
Individual technical economy can vary by as much as 20% and more for less skilled skiers. That is, at the same speed one athlete may use 20% less oxygen than another athlete to produce energy. We also know from a wide body of research that the metabolic cost of skiing in flat terrain at race pace can be as much as 30% lower than in uphill terrain. This is due in part to a large contribution of the upper body in the V2 techniques, and in general reduced muscle mass activation when on the flat terrain.
Given the complexity of the issue, answering this question is difficult, but to simplify and generalize...the energy cost of racing on a flat course should be lower than the cost on a hilly course. It is likely that on a hilly course the anaerobic energy system will be functioning at a higher level and as a result, the subsequent glycogen depletion will bring muscle fatigue on more quickly. In either race topography, the limitation is the ability to deliver oxygen to the working muscles to produce aerobic energy, the availability of substrates used for energy at the local level of the muscle, and the ability of the muscles to produce power and to sustain contractions. In the short term, the most reasonable way to improve economy is to improve technique and muscle power function.
Galanes Sports Lab Institute jimgalanes.com
As you would probably presume, we don't get to use zero skis too often here in Anchorage. However, with so much new snow and many Chinook winds with high temperatures and rain, it's been very optimal zero conditions. This season, I purchased a pair, and have no clue as to what types of grit of sandpaper to use or methods to prep my zeros. If you could please enlighten me of any special care or preparations of my zeros, I'd greatly appreciate it.
How to prep Zero Classic skis
Zero skis are optimal when it is snowing wet and heavy snow and when there are large fluctuations in temperature. In these conditions the zero skis provide kick while normal kick wax ices up resulting in slippery skis.
Zero skis are produced with a rubber inlay in the wax pocket zone that needs to be prepared before skiing. Rubbing the base of the ski makes the hairs, which lie in the base material, stand up. These standing hairs provide the grip needed for wet/zero snow conditions. Coarser rubs will be required for more humid snow, i.e. wet, heavy snow. Finer rubs are used for aggressive snow, i.e. snow with lower humidity. The rubbed area stays ice free by rubbing in an anti icing solution. Glide zones must be waxed like for a normal classic ski.
Rubber inlay in the wax packet zone of the Salomon Zero classic skis
What you need:
- Sand paper: 60, 80, 100, 120 grain
- Anti icing solution (Start or other brands)
- Start by wrapping a piece of coarse sand paper (60 or 80 grain) around a cork.
- Rub the hardest part of the camber (under the binding). Continue rubbing 15-20 cm forwards and backwards from this point. Important: make sure to remain in the center of the ski with the coarsest sand paper, not rubbing too far toward the tip or the end. Rubbing too far from the center will damage the glide zone and result in slower skis. Rub the kick zone area of the ski several times to force the hairs to stand up. Repeat rubbing from both sides to create a cross pattern.
- Switch to a finer sand paper (80-100 grain). Wrap the sand paper around the scraper or cork and work as described above. Start rubbing at the end of the coarse rubbing zone and work towards the ends of the special base material. Rub backwards and forwards.
- Work the final 5-10cm on each end of the kick zone (special base material) with fine sand paper, 100-120 grain.
- Rub Start Anticing Solution in the rubbing zone making sure to cover the entire kick zone. This solution is very thin and does not interfere with the dry friction that is involved in getting the kick.
If, when you try your ski they are sticky, the kick can be mellowed by using a finer sand paper (4 or 5 passes). If you need more kick, use a slightly coarser sand paper in the center of the kick zone. This method allows you to adjust your kick as you would with traditional kick wax.
Exercising in Cold Weather
by Allen Lim
from Skratch Labs skratchlabs
So far, every time I've gotten on a plane this year, I've flown to somewhere colder than where I was previously. I started the year in Los Angeles, leaving LAX at a nice balmy 70˚F, before heading back home to Colorado where temperatures were a cold but manageable 40˚F. Unfortunately, things started really getting tough when I headed out to spend the week in Verona, Wisconsin for the Cyclocross National Championships, where we brought the Skratch Lab's kitchen trailer to cook for racers and spectators. I knew it was going to be cold heading out, but working in 20 to 30˚F temperatures all day was a harsh reminder of all of the challenges and risks associated with exercise and exposure in sub-freezing temperatures.
While I've spent a large part of my career thinking about how to improve performance in hot weather conditions, the reality is that humans are extremely well suited to cope with the heat. When it gets hot, we easily and effectively redirect blood flow to help dissipate heat to the skin, we sweat to help cool that skin, we make quick hormonal adaptations that increase our ability to hold and store water, and we become more efficient at this whole process the more we are exposed to the heat.... read more here at skratchlabs
At the Birkie Expo
Get your Proflips, Pursuits, Pace and Velo
and enjoy the Birkie with relaxed and warm eyes.
Proflip from $116.90
Pursuit XT and Pace from $77.90
Motion and Speed $39.90
It likely to be cold temps between 6 F and 19 F
Likely a Start Green Day
Base: LF08 Green Low Fluorinated wax
Glide: HF80 Green High Fluor glider (perhaps HF70 if it gets warmer)
Base: Base wax mixed with Synthetic Purple with heat
Kick: Spread good layer of Synthetic Blue on the Base. On the top lay some good layers of Blue RF. Heat the mixing with iron and let cool down. Smooth outside with cork.
Start note: Spread one thin layer of Tar Blue (-2°...-6°C) kick wax on the to get greater glide.
START your BIRKIE
at the START EXPO BOOTH
Visit the Start Booth at the Birkie Expo to get up to the minute wax recs and purchase the winning wax combo.
|If you get your skis waxed at Riverbrook you will get waxed where last year's winners had their skis waxed. Read more about Caldwell Sport winning skis and wax jobs applied at Riverbrook here |
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Nordic Worlds Fiemme Contest
SkiTrax FIS Fantasy Fiemme Worlds 2013 Contest Launching Soon - Salomon Grand Prize Worth $1,497
We are thrilled to announce that Salomon has come on board with a fabulous S-Lab grand prize package including skis, poles, boots and bindings valued at $1,497 for our final fantasy contest this season the FIS Fantasy Fiemme Worlds 2013 Contest launching soon.
The 2013 Nordic World Championships take place from Feb. 20-March 3 in Val di Fiemme, Italy and we'll have lots of coverage and more contest news soon.
Check out our visit with Salomon's Isaac Wilson at the SIA Show 2013 Demo at Devil's Thumb Ranch in Colorado for the inside scoop on Salomon's new 2013/2014 S-Lab ski and boot line HERE.
for more info visit www.skitrax.com
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