Tessa is an epidemiologist with expertise in the measurement of physical activity in population surveys. She also researches the associations between physical activity and health outcomes using device-based measures of activity.

Tessa undertook her PhD at the University of Edinburgh (2014-2017) before moving to the MRC Epidemiology Unit (University of Cambridge) as a Post-Doctoral Fellow. She was promoted to Senior Research Associate in 2022. Tessa returned to the University of Edinburgh in 2023 whilst undertaking consultancy work for the World Health Organization. She was awarded a Chancellor's Fellowship in 2024.

Tessa has led a number of major projects resulting in publications in high-impact journals. These include:

• estimates of adult physical activity levels for 197 countries from 2000-2022 (Lancet Global Health);
• the first prospective analysis of device measured activity and mortality risk using UK Biobank data, focussing on the importance of activity intensity (Nature Medicine);
• the application of the Prevented Fraction for the Population to global physical activity data to quantify deaths averted by current levels of activity (Lancet Global Health);
• the largest nationally representative analysis of physical activity levels in the UK during the first COVID-19 lockdown (Lancet Regional Health Europe);
• and an investigation into the relative contributions of different domains of activity (work/household, travel, leisure) to 104 countries worldwide (British Journal of Sports Medicine).
  
  

Tessa also regularly contributes to policy discussions around the measurement of physical activity in the four UK home nations. She co-chaired a Chief Medical Officer appointed expert group on physical activity surveillance 2019-2021 and continues to work to implement the recommendations made.