Addressing the Scottish Sports Council's coach education conference in Glasgow, Dr Campbell criticised "overambitious, overzealous" parents who failed to understand their children's development.
She said coaches had to explain to parents how to support endeavour rather than only supporting victory, to encourage rather than chastise and to show good sporting behaviour. "Without this parent education there is a danger that children can become disillusioned with sport or are burnt out at a very young age."
Dr Campbell, who is based at Loughborough University and is a former chief executive of the National Coaching Foundation, believes children aged 7-10 should be exposed to a range of activities centred around body management and skill development. "Young children of this age enjoy mastering skills as long as they are challenging and achievable. Coaches need to stretch the task to meet the needs of all abilities, not simply the talented few," she stated.
Primary pupils were not ready for team games and playing in a certain position. "All the youngsters want to do is get the ball, run the length of the field and score. Passing never enters their head," Dr Campbell said.
She favours small-sided games to allow maximum involvement and skill development and says competition does not have to be discouraged. But encouragement and praise for effort are vital. "What the adult says and the way they respond will determine the child's behaviour," she said.
Dr Campbell advocated more structured approaches for the 11 to 14-year-olds to identify talent. But she cautioned: "Too much selectivity too soon can lead to a scarcity of numbers later on and the exclusion of late developers."
She added: "Those who do make it do so often despite the system and not because of it."