He has built a reputation for treating foot and ankle injuries in top international athletes - soccer players from the English Premier League and European clubs including Paris St Germain, AC Milan, Barcelona FC, Real Madrid, Olympique de Marseille FC in addition to rugby players from England, Ireland, Scotland and Wales, GB Olympic teams, England and Indian cricket teams and UK Athletics.

Calder was made a Fellow of the Faculty of Sports and Exercise Medicine, Royal College of Surgeons in Edinburgh in 2007 and in 2017 he was awarded a PhD by the University of Amsterdam.

[5] He has authored and edited several books, chapters and original papers related to the advancement of understanding sporting foot and ankle, tendon and cartilage injuries.

The Minister for Sport, Stuart Andrew MP, appointed Calder Chair of the committee of domestic and international experts to produce guidelines in the Government’s Action Plan on Concussion.

Announcement of the Guidance received a positive response across stakeholders and the public,[11][12] with Sir Chris Whitty, Chief Medical Officer for England and Chief Medical Advisor to the UK Government recognising that it helped “players, referees, schools, parents and others balance the substantial health and social benefits and enjoyment from taking part in sport with minimising the rare but serious and potentially lifelong effects of concussion”.

Simon Shaw MBE, former England rugby union player and President of the ‘Love of the Game’ campaign, stated “This guidance will help everyone involved in grassroots sport recognise the signs of concussion and remove people from play where necessary.

The information is clear: ‘If in doubt, sit them out’.” Calder continued to Chair UK Government groups co-ordinating research and the development of innovation and technology in concussion and traumatic brain injuries.

Early in the pandemic, the quest to increase ventilator capacity in the NHS led to the concept of converting the Excel Exhibition Centre into a 4000-bed critical care facility.

[18] This reported on the environmental and behavioural risk factors associated with the transmission of SARS-CoV-19 in more than 2 million participants at 31 pilot events across various sectors including sports, theatre, nightclubs and festivals.

A joint study between Imperial College London and Liverpool School of Tropical Medicine using live COVID-19 virus demonstrated that the risk of its transmission from shared use of sports equipment was very unlikely.