Establishing Standardized Levels for the CMJ and SJ Tests Integrated into the My Jump 2 App: An Indicator for Selecting Algerian U13 football Players
This study utilized a descriptive survey of 252 Algerian U13 football players to establish standardized performance levels for Countermovement Jump (CMJ) and Squat Jump (SJ) tests via the My Jump 2 app, providing coaches with objective criteria for player selection.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
Imagine you are a coach trying to find the next superstar soccer player. You have a huge team of kids, but you can't watch every single one of them play for a hundred hours to see who has the best legs. You need a shortcut, a way to peek under the hood and see how much "explosive power" a player's legs have. In the world of sports science, this power is often measured by how high a player can jump. Think of your legs like a spring-loaded pogo stick; the stronger the spring, the higher you fly. Scientists have long used big, clunky machines in labs to measure this, but those are expensive and hard to carry to a muddy soccer field. Enter the smartphone: a pocket-sized tool that can now act like a high-tech lab. This paper lives in the corner of sports science called "talent identification," which is basically the art of using data to spot future champions before they become famous. The big question here is simple: Can we use a phone app to create a fair, standard "scorecard" for young soccer players, so coaches know exactly who is a "very good" jumper and who needs more practice?
The story in this paper is about a researcher named Haroune Dif who decided to build that scorecard for 13-year-old soccer players in eastern Algeria. He gathered a massive group of 252 young players from 18 different teams and academies. Instead of using expensive lab equipment, he used a low-cost, portable, and easy-to-use smartphone application called "My Jump 2" on a smartphone. He had the kids perform two specific types of jumps: the "Counter-Movement Jump" (CMJ), which is like a quick dip and spring up, and the "Squat Jump" (SJ), which is jumping straight up from a crouch without that little dip first. The researcher treated the phone like a stopwatch and a ruler combined, capturing the jumps on video to calculate exactly how high they went in centimeters.
After collecting all the data, the researcher did some serious math to see if the results formed a nice, predictable pattern, like a bell curve. They did! This meant he could create a "standardized level" system, which is just a fancy way of saying he made a grading chart. He divided the players into five distinct categories based on their jump heights. For the Counter-Movement Jump (CMJ), the average player jumped about 24.52 cm. The chart showed that if a player jumped between 32.24 cm and 37.328 cm, they were in the "Very Good" zone (the top 5%). If they jumped between 27.082 cm and 32.24 cm, they were "Good." Most of the players, however, landed in the "Acceptable" range, jumping between 21.958 cm and 27.082 cm. A smaller group fell into the "Weak" category (16.958 cm to 21.958 cm), and sadly, no one in this specific group fell into the "Very Weak" category (11.834 cm to 16.958 cm).
The Squat Jump (SJ) told a very similar story. The average jump here was 22.59 cm. The "Very Good" threshold started at 30.475 cm and went up to 35.73 cm. Again, the majority of the players (about 45%) were in the "Acceptable" range (19.962 cm to 25.218 cm), with a solid chunk in the "Poor" range (14.706 cm to 19.962 cm). The researcher found that the phone app was incredibly reliable, giving consistent results every time they tested the same kids, proving it was a trustworthy tool.
The main takeaway from this study is that these standardized levels are real and usable. The researcher suggests that coaches should stop guessing and start using these specific numbers as a guide. If a coach is looking for a player with explosive leg power, they now have a clear ruler to measure against. However, it is very important to remember that these specific levels and the grading chart apply exclusively to 13-year-old players. These numbers should not be used as a benchmark or a reference for athletes in any other age groups. The paper argues that relying on these objective numbers helps prevent coaches from accidentally overlooking talented kids who might just look a bit different but have the right physical engine. While the study confirms that these levels work for this specific group of 13-year-olds in eastern Algeria, it also hints that this method could be a roadmap for the future, helping to build a stronger foundation for soccer talent selection across the country. The paper doesn't claim this solves every problem in sports, but it does offer a clear, scientific way to start the conversation about who has the best springs in their legs.
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