• Some teams have difficulty finding the requisite number of players of the opposite sex and end up losing the game by default because of it.
• When Co-ed teams are lacking in players of a specific sex, the few players available are obliged to play much longer than usual. They are often very tired by the end of the game and team performance generally suffers for it.

- Lack of Quality:

• Many men, who are usually faster and stronger than women, get frustrated when they face women and find they have to slow down. They may end up not enjoying themselves and may also feel they can’t express themselves fully.
• Women can experience frustration as well. Often, they are not taken seriously during the game by men who are afraid of hurting or overpowering them.
• The fact that players in Co-ed leagues try to be gentle with one another can affect the game in a negative way. More competitive players might not enjoy the game as much.

- Rare, but Severe Injuries:

• Sport injuries that occur when weaker players try to perform at the same level as stronger players of the opposite sex can be dangerous.
• Some players who don't understand the game and get invited just to fill the quota sometimes don't understand the concept of tackle, shield, advantage, "First to the ball" and can create injuries by doing things that the opponents are not expecting. It sometimes results in very bad injuries.
• Clumsy players who join the game to fill the quota or just to play with their date or partner usually end up hurting themselves or their opponent by not knowing when to slow down or get away from players who are very fast or skillful.

- Jealousy:

• The potential attraction between players of opposing sexes can sometimes create conflicts and jealousy from other players and this can affect the game negatively.
• Some players go to specific teams just to court other players from the opposite sex and the game is not their priority. This can affect the game negatively.
• Some players can be rejected by a love interest in the same team and they don't always cope well with the rejection. In those cases, the atmosphere of the team is sometimes ruined and the team ends up losing at least one of the players concerned. When teams lose female members, it is hard to replace them and they end up forfeiting some games by not having enough female members.

- Statistics of Co-Ed Sport Teams vs Men Teams and Women Teams:

To conclude:

• Co-ed games or mixed team sports have more positives than negatives. However, I recommend it for mature, older players as they are more likely to have the patience and self-control to enjoy this type of game. Kids under 6 can also play co-ed for a practical reason. At that age, there are not just enough girls to form a complete team in a girl only league. At that age also, boys and girl can safely play together without any need of self control.
• On a recreational and amateur level, many sports feature co-ed teams and leagues and it is growing very fast. The most notables amateur sports with co-ed leagues and teams are soccer, basketball, volleyball, ultimate frisbee, softball, flag football. Official competitions featuring co-ed or mixed teams so far are limited to ultimate Frisbee, double tennis, equestrian

Various Question and Answers about Co-Ed Sport games, teams and leagues around the world

Does FIFA allow women on men's football (soccer) teams if they are good enough?

• According to FIFA, it is a local issue: they have no ban on women playing in the men’s game.
  Read Sam Sinai's answer to When will FIFA allow men and women playing football together? on Quora
• Read Sam Sinai's answer to When will FIFA allow men and women playing football together? on Quora

What sport, played or competed by both genders respectively, in which women are more dominant than men?

• Gymnastics
• Figure Skating
• Netball
• Synchronized Swimming
• Roller Derby
• Softball
• Roller Derby
• Field Hockey

Why do we still have separate men and women categories in sports, when we both are equal?

In what sport can male and female athletes compete with each other professionally?

• Motor sports: There is no restriction on female drivers in 4 wheel motor sports - I am not sure about motorbikes - but certainly not in cars. You mention Danica Patrick but I think Maryeve Dufault has competed in Nascar also. Milka Duno has competed in Indycar and there have been a number of female F1 racers the best of whom was probably Lella Lombardi who competed in 17 F1 Grand Prix, and is to date the only female driver to have scored world championship points. She was a good sports car driver too. The most recent was María de Villota who was a test driver for the Marussia team in 2012 until she crashed in testing.
• Equestrian sports: Its strange to think that this most old fashioned of sports - is perhaps the one with the most equality. Men and women compete equally in showjumping, dressage, and cross country . In Dressage, women have won the Olympic Gold Medal at the last 7 Olympics, and in the last 4 Olympics have won all 3 medals. In Eventing women have won individual silver and bronze at the last 3 Olympics and team gold at the last 2, and in Showjumping women won gold, silver and bronze team medals at Beijing. Anne, Princess Royal even competed in the Olympics for Great Britain
• Horse Racing: There have been quite a few female jockeys in the US, the first licensed jockey being Penny Ann Early and the most successful probably being Donna Barton Brothers
• Sailing - Ocean Racing: Olympic sailing segregates male and female participants, but in long distance racing there are no restrictions. For example, more than a thousand women have competed in the Sydney to Hobart Yacht Race
• Racquet Sports: Mixed doubles are competed in most racquet sports, such as tennis, badminton and table tennis. But there is no "open" competition
• Chess: Although male dominated, men and women can play each other in open competition. The most successful female chess player is Judit Polgár
• Curling: A mixed doubles competition is available for curling
• Ice Skating: Skating features mixed Ice Dance, and Ice Dancing competitions, but no open competition for men and women to compete openly against each other
• Climbing: Climbing is mainly based on open competition