THE POLISH SKIER BALANCE STUDY: IMPLICATIONS FOR THE FUTURE OF SKIING


The foot functions best in skiing when it’s joints are immobilized in a tightly fitting ski boot, preferably in a neutral position with the arch fully supported by a footbed.

This widely held position within the ranks of the ski industry implies that immobilizing the joints of the foot in a ski boot has positive benefits for skiers.

But the authors of the Polish study (1) that was the subject of a recent post cite research that indicates otherwise:

Wearing ski boots for a few hours can lead to a weakening of the muscles that operate within the ankle joint. This works as though one joint was excluded from the locomotive function.

………. according to Caplan et al. [3], the muscle groups that determine strength and are responsible for the function of stability in the ankle joint are very sensitive to changes caused by immobilisation. They found that immediately after immobilising the ankle joint for a week, the balance parameters were 50% lower than before the immobilisation.

The authors of an earlier Polish study (2) on skier balance also cite research that indicates otherwise:

It must be mentioned that the stiff ski boots of skiers facilitate the transfer of power to the skis, but they also increase the difficulty in maintaining postural control. Mildner et al. (2010) showed that balance performance on the MFT S3-Check was negatively influenced when wearing ski boots.

The authors of the recent Polish study (1) further commented:

Publications on issues related to the biomechanics of a descent, with particular emphasis on the balance parameters, are rare in the literature on alpine skiing.

The authors of a 2014 Polish study (2) on skier balance, similarly commented:

Our results were in agreement with the scarce information available regarding balance changes during or after a ski training camp.

The authors of a 2013 Italian study (3) made a similar comment with regard to ski equipment.

Despite the large market of ski equipment, not many scientific papers have been published on this subject in the past.

If research on balance in alpine skiing is rare and scarce in the literature and not many scientific papers have been published on ski equipmentwhere did the foot functions best in skiing when its joints are immobilized in a ski boot story come from?

The most plausible explanation is that the story was simply invented to distract attention away from the fact that no one knows what happens when the foot is constrained within the rigid shell of a ski boot.

Inventing a cover story is a typical strategy used when an issue can’t be explained. Using fact-deficient or obfuscating generalities to appear knowledgeable on a subject is not the same as being knowledgeable. Yet, few question this tactic. Instead, they assume that they’re just not smart enough to understand it and they ignore their judgment and common sense. Once people buy into a cover story, information bias sets in and they unconsciously filter out any information that challenges what they have chosen to believe.

The two Polish studies (1), (2) should be taken seriously by the ski industry because that the authors used barefoot balance as a reference against which to assess the effects of the ski boot and balance training on skier balance. In addition, the recent Polish  study (1) employed a systematic protocol; one that standardized conditions, controlled variables and acquired data that could be objectively quantified as opposed to subjectively interpreted based on uninformed observation. If balance was worse or improved after training, or in tests done with subjects wearing ski boots compared to the barefoot baseline, the protocol provided compelling evidence of the cause of the change.

The test subjects were closely matched in terms of physical characteristics and included both skiers and non skiers.

The findings of the study were as follows:

In the trials involving standing barefoot, there were no significant differences between the measurements taken at the beginning and at the end of the training programme. 

In none of the tests conducted on both feet were significant differences in the length of the COP path observed between the group of beginners and the group of advanced skiers.

In the case of standing on one foot, no signifcant differences were observed in the sway range in the frontal and sagittal planes between the measurements taken before and after the training camp (Table 3).

In both groups, a statistically significant improvement in stability was observed after the training camp only while standing in ski boots, both with the eyes open and the eyes closed (Fig. 2). 

The earlier Polish study (2) also did balance tests without subjects wearing shoes. The authors commented that:

It must be mentioned that the stiff ski boots of skiers facilitate the transfer of power to the skis, but they also increase the difficulty in maintaining postural control. Mildner et al. (2010) showed that balance performance on the MFT S3-Check was negatively influenced when wearing ski boots.

A study by Noé et al. (2009) found that mechanical effects of wearing ski boots resulted in changes in postural strategy through the reorganization of muscle coordination in experienced skiers. The improvements in balance performance in our study could also be explained by guided skiing including a number of lateral and fore-aft drills over a week of skiing. Exercises such as skiing only on the outside ski with the inside leg raised or skiing without poles are part of the curricula of ski instructor associations.

While this may sound like a good thing, the Polish study (1) found that the normal balance process was worsened:

What is interesting is that in the measurements involving the participants standing barefoot with their eyes open, significantly greater sways in the sagittal plane were observed after the training camp than before it.

My Hypothesis on How Elite Skiers Balance on the Outside Ski

In 1991, after having spent more than 10 years trying to solve the mystery of how the world’s best skiers are able to balance on their outside ski, I was about to embark on a project to design and produce a radical new ski boot. The design of the ski boot was based on my theory that the world’s best skiers balance on the outside ski through a sequential tightening of the bio kinetic chain that engages the processes of pronation followed by the application of internal axial rotation of the femur of the outside leg of a turn from the pelvis. The  bio kinetic chain is closed through inclination. Once the bio kinetic chain is closed by locking the inside edge of the ski into the snow,  internal axial rotation of the femur applied to the outside leg is translated through the subtalar joint into dual plane torque that opposes the torque that is inverting the outside ski (i.e. rotating it away from the turn). In effect, this bio kinetic mechanism enables the world’s best skiers to truly balance on the outside ski by balancing multi plane torques. The problem I faced was that I had no way to prove my theory. The technology I needed did not exist.

With the immobilization works best cover story already under a microscope as I was poised to move forward to try and design and develop a new ski boot, I found myself staring down the barrel of a loaded gun. I needed to prove my theory. But since the technology  to do this didn’t exist, I insisted that MACPOD retain a science team to work with me to see if we could develop a technology with which to confirm my theory and the bio kinetic sequence it predicted. The process resulted in the Birdcage and the on-hill studies done in the summer of 1991 using elite, intermediate and novice skiers. The most significant aspect of the Birdcage research vehicle was that it allowed the capture of baseline skier data equivalent to barefoot function and the study the effect of constraining specific joints.

The increasing use of protocols such as the one used for the Polish study (1) in combination with the rapidly evolving field of micro sensor technology and data analysis  is making quickly making the vision of the Birdcage as an analytical tool for activities like skiing and skating a reality. As this unfolds, widely held beliefs that are the foundation of skiing will increasingly come under the lens of a microscope.


(1) Influence of a nine-day alpine ski training programme on the postural stability of people with different levels of skills  (April 2016, Biomedical Human Kinetics (DOI: 10.1515/bhk-2016-0004) – Michał Staniszewski, Przemysław Zybko and  Ida Wiszomirska,  Józef Piłsudski University, Warsaw, Poland.

(2) Changes in the Balance Performance of Polish Recreational Skiers after Seven Days of Alpine Skiing – Beata Wojtyczek, Małgorzata Pasławska, Christian Raschner

(3) Materials, Designs and Standards Used in Ski-Boots for Alpine Skiing: Martino Colonna *, Marco Nicotra and Matteo Moncalero