Montana State University

Mountains and Minds

Slick Science October 13, 2010 by Anne Cantrell • Published 10/13/10

MSU human performance research has practical applications for recreational skiers
It's late fall and the snow watch is on in Bozeman. While other places in the country frequently dread the onset of winter, many people in Bozeman count the days to when they can first strap on their Nordic or downhill skis or snowboard.

Given the emphasis on skiing in the Gallatin Valley, it's not surprising that skiing research thrives at Montana State University.

John Seifert and Dan Heil, who teach in MSU's Department of Health and Human Development, and their undergraduate and graduate students, research some of the most advanced issues in human performance. Their research topics include endurance performance of elite athletes, energy expenditure in movement, body position in bicycle design, and the influence of cold air inhalation on pulmonary and cardiac functions in chronic obstructive pulmonary disease (COPD) patients.

They also research some topics that can help sports enthusiasts understand how choices about equipment, hydration and body position relate to performance and enjoyment while skiing. Heil and Seifert say the results should be of interest to recreational and elite skiers alike.

Read on to learn more about how some of Seifert's and Heil's MSU research findings can help you be a better skier and enjoy the sport more.

Seifert, an internationally recognized expert on alpine skiing research, often conducts his studies at Bridger Bowl, the local ski hill just north of town. He and his students search for the answers to such questions as "Do sports and energy drinks help people perform better?" "What is the ideal placement for snowboard bindings to maximize comfort when riding?" And, "What gear performs the best in various conditions?"

One of Seifert's recent studies rates climbing skins. Skins stick to the bottom of skis and enable skiers to grip the snow as they climb uphill. The skins are a necessity for any skier or snowboarder heading into the backcountry. However, there are numerous options available for purchase. How do skiers know which skins will perform best and subsequently choose which ones to buy?

MSU Experts top 10 suggestions to improve your skiing performance.
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Seifert and MSU graduate student Sarah Williams are conducting a study to determine the best kind of material for climbing skins. Funded by a company that manufactures climbing skins, the study will examine the effectiveness of a variety of different materials, including mohair and synthetic.

Williams and Seifert will measure the time it takes study participants to ski a course, as well as the participants' heart rates. These measurements will be taken as the skiers use a variety of different types of skins in controlled conditions.

"If you're slipping more, you'll have to change your body mechanics," Williams said. "For example, if you have to bend your knees more to prevent slipping, it pumps up your heart rate. This probably means the skin you're using isn't as good."

"People are curious about how small factors affect their performance," she said. "People want to ski better and improve. They're interested in what kind of products to use and how their bodies respond to different conditions. This study will help people make informed decisions about the gear to use."

Another one of Seifert's studies examines how powder skis behave in deep powder versus groomed runs. It also determines the energy expenditure of skiers on groomed runs versus deep powder. The study relies on the use of accelerometers, tiny instruments the researchers mount above a ski binding that measure tilt and acceleration of the ski.

For people looking for the best ski to use in various conditions, take note: there's a time and a place for using powder skis, and it's not your everyday trip to the mountain.

Powder skis are a type of ski designed solely for skiing in deep snow. They tend to be shorter than the traditional all-mountain skis, and they're also typically much wider, which helps the skier float closer to the surface of the snow.
All-mountain skis are usually between 70 and 80 mm wide, while powder skis can be as wide as 140 millimeters.

Seifert has found that skiers' heart rates are from five to 10 percent greater when they ski groomed runs on powder skis instead of on skis of normal width. Meanwhile, acceleration when using powder skis on groomed runs is, on average, about 50 percent greater.

"Large stresses are incurred by a skier using powder skis on groomed runs," Seifert said. "It's a lot harder to make turns, and the skiers have to do something to deal with increased acceleration. They either have to ski faster or produce more force to turn or slow the skis down."
"Using powder skis on groomers beats your body up a lot," he said.

Heil focuses primarily on Nordic skiing. Like Seifert, he is a well-regarded researcher and has published widely. His diverse studies range from the accuracy of pedometers to energy expenditure in high-performance athletes and wildland firefighters. Heil also serves as the director of the Movement Science/Human Performance Lab at MSU, which performs a variety of strength and endurance tests on local master and junior Nordic skiers, as well as members of MSU's Nordic ski team.

Many of Heil's studies have real-world applications for people seeking ways to improve their abilities on snow. Nordic skiers who are looking for ways to tweak their performances will especially want to note Heil's research of ski pole grips.

His 2003 study proved that thumb ledges give cross-country skiers a significant advantage over skiers using different types of gripping systems. Heil had several Nordic skiers in Bozeman, including Jon Engen, a three-time Olympian in Nordic skiing and the biathlon, perform a test in MSU's Human Performance Lab. The test measured the skiers' upper body power while using a modified ergometer with ski poles to test three kinds of gripping systems. The traditional gripping system uses a simple wrist band attached to the top of the ski pole. The modern system, besides having a wrist strap, has a Velcro band that wraps around the back of the hand. The integrated system is similar to the modern system, but has a thumb ledge, which simply provides a different ergonomic interface between the hand and a ski pole.

As the skiers pushed back on their poles, Heil measured and recorded their upper body power in watts.
It was clear that skiers had more power when they used thumb ledges, Heil concluded, but it wasn't because they changed their technique. Rather, the different ergonomic grip allowed the skiers to apply force through a greater range of motion.
"The skiers' upper body power was able to be transferred more effectively because the interface between the hand and pole was better designed," he explained.

"Frankly, I was surprised by the results," Heil said of his study. "I wasn't expecting to actually find significant differences in pole grips. Equipment issues are such that often times, if there's any type of performance advantage by using one piece of equipment over another, it's almost impossible to truly measure that difference."

Previous research has found that upper body power correlates with Nordic skiers' performance: the more powerful the upper body, the better the performance. Because the degree of stiffness of ski poles could influence upper body power, Heil and graduate student Erik Jacobson (who graduated when the study was completed in the spring of 2008) set out to investigate further.

Cost differences are certainly apparent among the different poles. Stiff cross-country ski poles, made of 100 percent carbon fiber, can cost about $320 per pair, while more flexible poles, made of 80 percent carbon fiber and 20 percent fiberglass, are about $170 a pair. Both types of poles are considered to be high-quality racing poles.

To learn more about how poles could affect performance, Heil and Jacobson measured the upper body power, in watts, of eight men and seven women as they used ski poles with varying levels of stiffness on a modified rowing ergometer. The 15 athletes were elite and college-level cross-country ski racers from the Bozeman area.

Heil and Jacobson found no significant power difference in the two pole types among the female athletes they studied, but the male athletes did harness more power using the stiffer carbon fiber poles. They found a significant increase in power for men using the stiffer poles during a 60-second test, as well as a tendency for men to have more power with the stiffer poles during 10-second tests.

Heil and Jacobson also found that the less expensive poles bent significantly more for male athletes during the test than the 100 percent carbon fiber poles, but did not find statistically significant differences in pole bending for the female athletes. However, even among the men, Heil and Jacobson found no direct relationship between the amount that a ski pole bends and the loss of power.

The takeaway is that differences in stiffness between high-end poles would only affect those people with the very highest upper body power, Heil said. It would also likely occur only when they are generating their highest levels of upper body power, such as when they are sprinting. Recreational skiers should realize that paying more in this instance for stiff ski poles probably wouldn't improve their performances.

While it is well known that it's important to stay hydrated, many skiers, either Nordic or downhill, are not fully aware of the repercussions of becoming dehydrated while skiing, Seifert says. He has found that dehydration can be a safety issue, and it can also affect people's enjoyment of the sport.

"The effects of dehydration are insidious: We don't feel thirsty, we don't feel sweaty, we don't realize how much water we lost just by breathing, and we misinterpret that warm, fuzzy and achy feeling that washes over our body during our fireside lunch as fatigue from a good morning of skiing or riding," Seifert wrote in an article on the subject. "What we don't realize is that the lethargy and stiffness may be attributable to dehydration."

In fact, Seifert says that it's hard to overemphasize the importance of hydration.

One of his studies examined the effects of hydration on advanced recreational skiers in Utah. He had three groups of skiers--all of whom were equally and fully hydrated at the start--ski at a resort as much as they desired for three hours.

While they skied, members of one group had nothing to drink, another group's members drank only water and members of the final group drank sport drinks. Each skier supplied blood and urine samples before and after skiing, and then Seifert analyzed skiers' hydration levels and presence of creatine kinase, an enzyme that is indicative of muscle stress.

Seifert found that after skiing, the skiers who had nothing to drink suffered from greater muscle stress than those drinking water and sport drinks. Further, changes in creatine kinase were significantly less for the sport-drinking group than the group that drank water, and for the water-drinking group than the non-drinking group.

Hydration levels also affected the skiers' performances. Group members drinking water and sport drinks outperformed the non-drinking group by skiing more laps per hour. The sport drink group performed the best, averaging nearly twice as many runs in the last hour as the non-drinking group.

"It's clear that there's a huge benefit to staying hydrated and even investing in energy drinks," Seifert said.