What are the sort of actions that could make me fall foul of gross misconduct?

These vary according to the sport, but an example from UK athletics may be illustrative and helpful. The following are examples of gross misconduct which may result in immediate de-selection from the World Class Performance programme:

• Actual or attempted theft, fraud or dishonesty.
• Sports betting, corrupt conduct, disclosure of confidential information pertaining to your sport and match fixing.
• Fighting, physical or sexual assault, violence, threatening behaviour or deliberate and serious damage to people or property.
• Anti-Doping Regulation Violations.
• Gross insubordination, including failure to comply with reasonable requests/instructions.
• Incapacity for training owing to the use of alcohol or illegal drugs.
• Serious breaches of your sports’ stated values.
• Deliberate actions or omissions that bring your sport’s name into serious disrepute.
• Gross negligence or incompetence which causes serious loss, damage or injury.
• Serious breaches of your sport’s rules relating to Health & Safety (and hygiene).
• Serious breaches of your sport’s Mobile Phones and Driving Policies.
• Bullying or harassment on the grounds of sex, race, disability, age, sexual orientation, religion or belief or any other protected characteristic of another Athlete, employee of your sports’ authority, visitor or any other third party to whom your sports body has a duty to prevent such discrimination.
• Indecent, offensive or immoral behaviour.
• Offensive use of social media, including unauthorised use or hacking of another person’s account.
• Disclosure of confidential information pertaining to your sport.
• Deliberate telephone, computer and e-mail misuse, including hacking and/or the access, downloading or transmission of any pornographic or otherwise offensive material.
• Violation of the rules outlined in the Code of Conduct.
• Encouraging or supporting a Paralympic Athlete to intentionally misrepresent themselves to a classification panel.