Protecting football and its image, consistency in performance, professional preparation and effective teamwork – these are the key messages Europe's leading referees are taking into the season after UEFA's summer gathering in Nyon.

Eighty-seven male referees and 18 female match officials from UEFA's highest categories put in crucial "hard yards" at the annual pre-season course that will serve them well in the months to come. Preparations were fine-tuned, referees' fitness levels were checked, the previous season was reviewed through video analysis and discussion, and instructions and recommendations were passed on through the UEFA Referees Committee.

UEFA chief refereeing officer Pierluigi Collina pulled no punches in reiterating UEFA's firm desire to protect the game. He urged referees, among other things, to take strict action against serious foul play and reckless tackling or challenges that could cause serious injury. "This protection is important for football," he said.

The issue of mobbing to put pressure on referees, and dissent towards match officials, is preoccupying the European body again, and Collina called on referees to protect themselves against such behaviour. "UEFA wants a positive message to come across from matches," he said. "[Referees] are part of the game and you must protect yourself as part of the game by taking disciplinary measures if needed.

"We don't look for friendship – we look for respect. You have to respect everybody on and off the field of play and they must respect you as the referee," Collina concluded. Matches in Europe’s major competitions are viewed across the world and receive extensive attention, and UEFA is concerned that the image of football portrayed should be a good one.

The referees are already gearing up for important assignments this season in the UEFA Champions League and UEFA Europa League – continuing with this week's play-offs – UEFA EURO 2016, UEFA Women's EURO 2017 qualifying and the UEFA Women's Champions League.

UEFA Referees Committee chairman Ángel María Villar Llona opened the course with positive encouragement. "Last season was a very good one for European referees," he said. "I hope the level will be maintained this season. Success depends on hard work and I would recommend you to prepare thoroughly, both mentally and physically."

"We are pleased with you," Collina told the referees, "but we are convinced that you can do even better. In particular, we would like to achieve consistency in performance, as we believe that this is a key to success. We have seen here how hard you are working and we are confident that that you will do well over what will be a long season."

The referees were briefed about the new guidelines on offside, issued recently by football's lawmakers, the International Football Association Board (IFAB), aimed at clarifying the interpretation of interfering with an opponent in the application of the Laws of the Game.

Consequently, players in offside positions will also be penalised if they clearly attempt to play a ball close to them when this action impacts on an opponent, or if a player makes an obvious action which clearly impacts on an opponent's ability to play the ball.

In addition to weight tests, all of the match officials took a fitness test under UEFA referee fitness expert Werner Helsen that included 10-metre and 40-metre sprints to measure their acceleration and sprint resistance, and the intermittent recovery 'yo-yo' test to look at their endurance powers.

Teamwork is becoming an increasingly significant aspect of refereeing. Collina urged clear and concise communication between match officials to bring about effective, correct decisions and quoted basketball legend Michael Jordan to emphasise his point: "Talent wins games, but teamwork wins championships."

The UEFA Referees Committee, featuring experienced former international referees, were on hand to give expert advice to the current generation of match officials. Collina and UEFA refereeing officers Hugh Dallas and Marc Batta were joined at the course by committee members Dagmar Damková (Czech Republic), David Elleray (England), Herbert Fandel (Germany), Bo Karlsson (Sweden), Nikolai Levnikov (Russia), Vladimir Sajn (Slovenia), Jaap Uilenberg (Netherlands) and Kyros Vassaras (Greece).