Running or Walking Efficiency when Climbing

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VK world record holder, Urban Zemmer

Recently I have produced a couple of articles about how to ensure that you are an efficient walker when participating in long or mountainous events. You can read them HERE and HERE.

The first article discusses Training to Walk for Ultra, Trail and Mountain Running and the second article is about Walking, Running and Climbing with Trekking Poles.

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On December 15th, the University of Colorado Boulder released a document called, CU-Boulder researchers discover optimal range of slopes for extreme uphill running.

This article made me take a look and read in-depth for two reasons: first and foremost it ties in nicely with my previous two articles but more importantly and secondly, research into VK data dates back some 16-years and was pioneered by the ISF (International Skyrunning Federation) who created the VK format as a racing discipline.

To clarify a VK is 1000m of vertical ascent and the objective is to climb the elevation gain as quickly as possible. The original context of the VK always was about research and data.

VK courses vary greatly but the ISF consider a true VK to be under 5km in length. To understand the variables, some VK’s, for example the Dolomites are just over 2km in length. By contrast, Limone Extreme is a considerably longer course with a less extreme gradient.

Fully, Switzerland has long been a testing ground for VK performance and a post from the ISF which was updated 22nd October 2012 adds some very clear and specific points to consider:

“Italy’s Urban Zemmer rocketed up the 1,000m vertical course, only 1.9 km long, in just 30’26”, 20 seconds faster than the standing world record set here in 2011.”

In addition, the ladies records tumbled:

“French runner Christel Dewalle was first in 36’48” followed by Axelle Mollaret in 37’44” and third, Maude Mathys from Switzerland in 37’56, all beating the previous world record set two years ago by Italian Valentina Belotti in 38’50.”

Notably, the ISF commented:

“The new men’s record nears a speed of 2,000 vertical metres per hour (precisely 1,971m) an incredible ground-breaking performance that the ISF has been monitoring for many years in a scientific research project… Depending on the course and type of start, poles are permitted and yesterday, most of the runners used them.  However, to date, the advantages of using poles has not been scientifically demonstrated.”

In 2014, the record for the VK was once again broken by Urban Zemmer at Fully, Switzerland with the incredible time of 29’ 42”.

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Remi Bonnet prefers to run a VK and never walks

So by simple logic (I am no scientist), it would suggest that the steepest course is the fastest as Fully is only 1.9km long. To quote, Run the Alps,The Vertical KM race in Fully, Switzerland is considered to be the fastest vertical kilometer course in the world. The race, held on a former funicular route, is home to both the men’s and women’s world records.”

You can watch a YouTube clip of the 2013 Fully race HERE

Watch the video of Fully and you will see varying techniques, some walk, some walk/ jog, some (most) use poles but one thing is consistent, the effort is almost maximal for all. Therefore, in a non-scientific look at Fully, the fastest performances come from the genetically gifted who have all the elements required for an optimum VK performance: lung capacity, V02max, lactate threshold, power to weight ratio, technique and so on.

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Marco de Gasperi like to mix running and walking

But what about the optimal slopes for uphill running as questioned by CU-Boulder. They posed the question:

“Imagine that you are standing in Colorado at a trailhead where the base elevation is 9,000 feet. Your friend challenges you to race to the summit of the mountain, which tops out at 12,280 feet, roughly 1,000 meters of elevation gain. There are several different trails that go to the summit. They are all steep and some are extremely steep. One trail averages a 10 degree incline and the sign says it is 3.6 miles long. A second trail averages 30 degrees, but is only 1.25 miles long. A third trail averages 40 degrees, but only 1 mile long. To get to the summit the fastest, which trail should you choose and should you walk or run?”

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Poles or no poles on a steep gradient?

This is a question that the ISF have asked and researched for many years. A paper titled, “Energy costs of walking and running uphill and downhill at extreme slopes” looks into this:

Davide Susta, Alberto E. Minetti*, Christian Moia and Guido Ferretti

Département de Physiologie, Centre Médical Universitaire, 1211 Genève 4, Switzerland, *Department of Exercise and Sport Science, Manchester Metropolitan University, Alsager ST7 2HL, U.K.

The energy costs of walking and running (Cw and Cr, respectively, in J kg-1 m-1) increase with the slope uphill (up to +20%) and decrease with the slope downhill (down to -10%) (Margaria, 1938; Margaria et al, 1963). Outside this range, no measurements of Cw and Cr are available in the literature, even though walking and running on the mountains at greater slopes is becoming commoner and commoner practice in leisure and sport. We therefore set out to carry out the present study, the aim of which is to determine Cw and Cr on men walking and running at slopes up to +45% and -45% on the treadmill. After local ethical approval, 10 subjects (Skyrunners) were admitted to the study (age 32.6 + 7.5 years, body mass 61.2 + 5.7 kg, maximal O2 consumption 68.9 + 3.8 ml min-1 kg-1). They are all endurance athletes practicing mountain racing. O2 consumption at the steady state was measured by the open circuit method, using Leybold O2 and CO2 analysers and a Singer dry gas meter. Heart rate was measured by cardiotachography. Blood lactate concentration was determined after each run as a check for submaximal aerobic exercise.

Each subject performed up to three walking and three running trials at progressively increasing speeds on the level, and at the slopes of 10, 20, 30, 35, 40 and 45 % uphill and downhill. The duration of each trial was 4 min, and expired gas was collected during the 4th min of exercise. Minimum Cw on the level was: 

1.85 + 0.57 J kg-1 m-1 (n = 10) at the speed of 0.69 m s-1. During uphill walking, Cw increased with the slope, to attainthevalueof18.08+1.57Jkg-1 m-1 (n=9)atthespeedof0.69ms-1 andat the slope of +45%. During downhill walking, minimum Cw was lower at the slope of -10% (0.81 + 0.37 J kg-1 m-1, n = 9) than on the level. At slopes below -10%, it progressively increased. At -45%, it was 3.46 + 0.95 J kg-1 m-1(n = 5). Cr on the level was 3.40 + 0.24 J kg-1 m-1(n = 30). Cr increased with the slope, to attain 18.69 + 1.42 J kg-1 m-1(n = 6) at +45%. 

During downhill running, Cr decreased and attained its lowest value at the slope of -20% (1.73 + 0.36 J kg-1 m-1, n = 24). At lower slopes, it increased. At -45%, at speeds higher than 1.38 m s-1, it was equal to 3.79 + 0.57 (n = 7). The mechanical efficiency for vertical displacement was 0.216 + 0.015 at +45% and 1.078 + 0.275 at -45%. This data on the level and at slopes up to 20% correspond to those found by others on non-athletic subjects (Margaria, 1938). At higher slopes, the increases in Cw and Cr are such as could be predicted assuming that all energy is used to lift the body. By contrast, at -10% and -20%, both Cw and Cr are lower than in non- athletic subjects (Margaria, 1938), suggesting greater recovery of elastic energy at each step in the present athletes. At slopes below -20%, the increases in Cw and Cr are such as could be predicted assuming that all energy expenditure is for negative muscle contractions.

REFERENCES
Margaria, R. (1938). Atti Acad. Naz. Lincei 7, 299-368.

Margaria, R., Cerretelli, P., Aghemo, P. & Sassi, G. (1963). J. Appl. Physiol. 18, 367-370. This work was supported by a grant from the FSA- Federation.for Sport at Altitude

Referring back to the CU-Boulder research:

“Based on our research, we now know that choosing the second trail (30 degrees) and walking as fast as you can within your aerobic capacity is the fastest way to go,” Kram said. “For either running or walking, slopes between 20 and 35 degrees require nearly the same amount of energy to climb the hill at the same vertical velocity.”

This new study (HERE), which was recently published in the Journal of Applied Physiology, is believed to be the first to examine the metabolic costs of human running and walking on such steep inclines (suggested by the CU-Boulder researchers.) However, I would question this and refer to research by the FSA – “Energy cost of walking and running at extreme uphill and downhill slopes.” Received 29 November 2001; accepted in final form 29 April 2002. You can download this detailed documentation HERE and it is essential reading.

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Who is the most efficient?

It would appear that gradients of 20-35 degrees require the same amount of effort and interestingly, CU-Boulder research found in a study:

“A vertical rate of ascent of just over 1 foot per second, is a pace that high-level athletes could sustain during the testing. At that speed, walking used about nine percent less energy than running. So, sub-elite athletes can ascend on very steep uphills faster by walking rather than running.”

In simple terms, this is something I have found out by attempting VK’s in my own time in and around events. More often than not, the effort required to run is so hard that it becomes counter productive. I have even found that including run sections to be counter productive as this raises my heart rate, increases lactate acid and requires me to recover while still climbing. However, if I maintain a constant effort walking, this produces the best results for me.

CU-Boulder research went on to say:

“The study examined 15 competitive mountain runners as they ran and walked on the treadmill at seven different angles ranging from 9 to 39 degrees. The treadmill speed was set so that the vertical rate of ascent was the same.  Thus, the treadmill speeds were slower on the steeper angles. The athletes were unable to balance at angles above 40 degrees, suggesting a natural limit on the feasible slope for a VK competition.”

In regard to the latter point, this in some respects relates to Fully, Switzerland and brings in another element, the use of poles and if poles allow a faster ascent when the gradient steepens. One only has to look at the Dolomites VK and Fully VK where poles are used by nearly all participants. The ISF plan to do a new test with and without ski poles, but it is not easy to do a serious test. Although not scientifically proven, it’s fair to say that using poles with gradients under 20% it will mean more Kcal and a reduced performance. However, with gradients steeper than 25 or 30%, the use of poles can correct style, etcetera and can improve the overall performance.

The CU-Boulder article is available to read in full HERE.

I can quote technical papers and research all day, however, as a runner you want to know the answer to the question, should I walk or should I run uphill and should I use poles?

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Irrespective of if you plan to run a VK or not, the research and thoughts provided by the FSA and CU-Boulder confirm that running or walking uphill provides an incredible workout. Importantly though, research confirms that walking should be a key element in any training plan, (*…walking used about nine percent less energy than running) especially if you are racing or training on hilly or mountainous terrain.

When participating in ultra events, reverting to periods of walking may well produce greater results and faster times. This is very evident when the terrain steepens; running will only expend more energy and produce slower times. The use of poles appears to benefit performance when gradients steepen, this is not scientifically confirmed.

On a final note though, many other factors come into play when looking at results and as with everything, there are exceptions. Urban Zemmer, Remi Bonnet, Laura Orgue, Christel Dewalle and so many more are able to run when others need to walk. We can’t choose our parents or our genetic pool. Ultimately, find out what works for you but practice makes perfect and the more climbing you do, the better and the faster you will become.

Embrace the mountains and going uphill.

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Christel Dewalle, ladies VK world record holder