Related Experiment Video
Updated: May 22, 2026
09:24
A Rapidly Incremented Tethered-Swimming Maximal Protocol for Cardiorespiratory Assessment of Swimmers
Published on: January 28, 2020
Quantifying instantaneous performance in alpine ski racing.
1Norwegian School of Sport Sciences, Ulleval Stadion, Oslo, P.O. box 4014, Norway. peter.federolf@nih.no
Journal of Sports Sciences
|May 25, 2012
Summary
Researchers developed a new metric, time loss per elevation difference (dt/dz), to objectively measure instantaneous alpine ski racing performance. This method quantifies how speed and path choices impact a skier's real-time efficiency on the course.
Area of Science:
- Sports Science
- Biomechanics
- Engineering
Background:
- Alpine ski racing performance is influenced by speed and path.
- Current methods lack objective, quantitative assessment of instantaneous performance.
- Optimizing athlete performance requires precise evaluation tools.
Purpose of the Study:
- Define a novel variable for instantaneous skiing performance.
- Quantify the impact of skier speed and path on performance.
- Introduce a new metric for objective performance analysis.
Main Methods:
- Defined instantaneous skiing performance as time loss per elevation difference (dt/dz).
- Incorporated skier speed (v(z)) and distance per elevation difference (ds/dz).
- Utilized kinematic data from six ski racers in slalom turns.
Main Results:
- Demonstrated a quantitative method to assess individual ski racer performance.
- Showcased the dependence of the new performance variable on speed and path.
- Provided a basis for objective, real-time performance evaluation.
Conclusions:
- The dt/dz metric offers an objective tool for assessing instantaneous skiing performance.
- This analysis aids athletes, coaches, sports scientists, and equipment engineers.
- Facilitates deeper understanding of ski racing technique and optimization.
Related Concept Videos
01:29Distance Problem
When an object's velocity changes over time, the total distance traveled can be determined by summing small displacement intervals over short increments. This approach approximates the true distance through numerical summation and the use of integral calculus. An estimate of the total displacement can be obtained by measuring velocity at regular intervals and multiplying each value by the corresponding time step.If a runner accelerates over the first three seconds of a race, speed measurements...
01:34Velocity and Position by Graphical Method
Velocity and position can be calculated from the known function of acceleration as a function of time. The total area under the acceleration-time graph and the velocity-time graph gives the change in velocity and position, respectively. In the case of an airplane, its acceleration is tracked using the inertial navigation system. The pilot provides the input of the airplane's initial position and velocity before takeoff. The inertial navigation system then uses the acceleration data to calculate...
01:10Instantaneous Velocity - II
Instantaneous velocity is the quantity that measures how fast an object is moving along its path. In other words, the instantaneous velocity of an object is the limit of the average velocity as the elapsed time approaches zero, or the derivative of displacement with respect to time. Like average velocity, the instantaneous velocity is a vector with the dimensions of length per unit time. Instantaneous velocity can have both positive and negative values. The instantaneous velocity can be...
01:16Instantaneous Acceleration
Acceleration is in the direction of the change in velocity, but it is not always in the direction of motion. When an object slows down, its acceleration is opposite to the direction of its motion. Although commonly referred to as deceleration, this causes confusion in our analysis as deceleration is not a vector, and does not point to a specific direction with respect to a coordinate system. Therefore, the term deceleration is not used. For example, when a subway train slows down, it...
01:18Application of Rates of Change
The movement of a car along a highway can be examined through key principles of calculus and kinematics. As the car travels, its position varies over time and can be represented mathematically as a function of time. Analyzing the rate of these changes enables the measurement of velocity and acceleration, fundamental aspects of motion analysis.Velocity describes how position changes over time. The average velocity during a specific time interval is calculated by dividing the change in position...
01:26Derivatives: Problem Solving
Temperature-Dependent Growth of Brook TroutThe growth of brook trout is closely influenced by water temperature. Experimental data demonstrate how trout weight changes over a 24-day period in response to varying water temperatures. At lower temperatures, such as 15.5 degrees Celsius, brook trout show significant weight gain. However, as the temperature increases, the amount of weight gained steadily decreases. At the highest temperature measured, 24.4 degrees Celsius, trout experience a net...