Eir Ball: The Research

From 2008 to 2012, we conducted research on injuries and ball behavior together with scientists in Denmark and Germany. At that time, we knew that asking FIFA and sports organizations to introduce a specialized ball for female players would be difficult. Those years, we were still thinking equality was playing with the same size ball as men.

Today (2024), we know better. The time might be right for everyone to exercise with equipment, including the ball, that's fitted to our bodies, optimizing performance and safety.

Key Facts from Sport

Most other sports – e.g. basketball, tennis, and golf – have adjusted the game/equipment to women to give the performer the best chance to succeed. Football/soccer stands out as one of the few sports where adjustment remains unaddressed.

SPORT

Basketball weight

Basketball circumference

Handball weight

Handball circumference

Athletics: Hedge

Athletics: Hammer et al.

Athletics: Javelin

WOMEN

325-375 g

54-56 cm

325-375 g

54-56 cm

84 cm

4 kg

600 g

MEN

567-650 g

74,9-78 cm

425-475 g

58-60 cm

106,7 cm

7,26 kg

800 g

Science-Backed Ball Design: How the Eir Ball Improves Women's Soccer

Shockingly, young female soccer players aged 14-19 suffers an average of one injury per year. And with a 90% risk of suffering a second injury, particularly ACL tears, many players retire from the game before they even reach their prime. 

Scientifically the Eir ball is developed specifically for female players, it tackles the problems caused by using a standard size 5 ball. Forcing players to hyperextend their leg for kicks puts undue stress on the knee and limits power. Heading a standard ball can also lead to dangerous head acceleration, exceeding concussion danger levels.

The Eir Ball offers a safer and more enjoyable playing experience. Here's how:

  • Increased Kicking Distance: If a specific player is able to kick a standard size 5 ball 33 meters, then the same player can kick the Eir ball 37.4 meters (13% longer).

  • Faster Passes: A 20-meter pass (not touching the ground) will take 0.91 seconds with a standard size 5 ball and 0.85 seconds (6% less) with an Eir ball.

  • Reduced Injury Risk: The Eir ball's design minimizes knee stress and lowers head acceleration during heading. Ball speed is higher when kicking the Eir ball vis-à-vis a standard size 5 ball (23.9 m/s vs. 22.5 m/s) – given no difference in the foot speed.

  • Improved Player Experience: 50% of the players find the Eir ball better than the standard size 5 ball and 86% of all respondents respond positively to the Eir ball.

These improvements highlight the potential of the Eir ball making it safer, faster, and more enjoyable for all.

“Among female soccer players who had sustained acl injuries, more than half developed x-ray signs of osteoarthritis in the following 12 years.”

— Marci A. Goolsby, MD, Attending Physician, Dept. of Medicine (Sports Medicine), Hospital for Special Surgery.

Rethinking the Ball to Improve Health and Performance

Injury incidence in adolescent female soccer is 15.3 per 1,000 hours of soccer exposure. This is extremely high.

The level of wear and tear strains is high. Strains of the legs are higher with a standard size 5 ball than with the Eir ball (5.2 vs. 3.7).

Players unaccustomed to the Eir ball spent too long time over 95% of HRmax and less relative time in the 80-90% of HRmax zone when playing with a standard size 5 ball.

Head acceleration will be significantly lower – even at an increased ball speed – when using the Eir ball with lower mass compared to the standard size 5 ball.

Female kickers tend to move both the thigh and the shank towards the ball, whereas male kickers only rotate their shank. Changing the movement with the Eir ball can remove pressure on the female knee close to zero.

With the Eir ball, elite women kick the ball with a 4% higher ball velocity.

Elite male football/soccer players achieve maximal ball speeds of approximately 30 m/s when kicking under laboratory conditions. Female players, however, only achieve speeds of up to 22 m/s.

“When the Eir ball is hit well, you can pass it further and more precise – both in the air and on the ground. The dribbling is faster and safer, especially when changing direction."

— Tina Theune, former national team coach for Germany, six-time UEFA Women's Championship winner, and one-time FIFA Women's World Cup winner.