Master athlete is generally someone over 35 year of age who competes in track and field events and/or cross country. This paper better explains the Master athlete and review the current exercise and treatment recommendations.
Paper: The Masters Athlete: A Review of Current Exercise and Treatment Recommendations: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4482301/
Here is a short summary of the nutrition needs of the master athlete. Not much is known, so one needs to make sure the nutrient needs of someone that age are meet and then increase needs for athletic performance.
Blog: Physiological Changes and Nutrition for Masters Athletes: https://journals.lww.com/acsm-healthfitness/Fulltext/2010/01000/Physiological_Changes_and_Nutrition_for_Masters.11.aspx