Martin is an Associate Professor in Gerontology at Swansea University. His main research interests are work and retirement in a global context. He has written on a wide range of topics from quality of life, work and retirement, health inequalities and globalization. He has published in peer reviewed journals, numerous reports and book chapters, as well as three books. He has been involved in a number of large scale studies including the English Longitudinal Study of Ageing (ELSA), the Survey for Health, Retirement and Ageing in Europe (SHARE) and the Swedish Longitudinal Occupational Study of Health (SLOSH). He is on the steering committee for a number of international studies, including the Iranian Longitudinal Study of Aging (IRILSA) and Inclusive Cities through Equitable access to Urban Mobility Infrastructures for Dhaka-Bangladesh (EQUIMOB).

He is heavily involved in a number of international professional organisations. He is on the Executive Committee of the British Society of Gerontology (BSG), the President of BSG Cymru, Chair of the BSG Work and Retirement Group, a Member at Large of the Sociology of Ageing (RC11) committee of the International Sociological Association and a Fellow of the Gerontological Society of America. He is a member of the Welsh Ministerial Advisory Forum on Ageing and of the International Organization for Standardization Technical Committee for an Ageing Workforce. He is a Deputy Editor for Ageing & Society, an Associate Editor for Social Theory and Health and on the editorial boards of the International Journal of Social Research Methodology and Quality in Ageing and Older Adults.