Muscle fiber capillarization is associated with various indices of skeletal muscle mass in healthy, older men

•Muscle fiber capillarization is positively associated with whole-body indices of skeletal muscle mass in older men.•Muscle fiber capillarization is not associated with post-absorptive muscle protein synthesis rates in older men.•Muscle fiber capillarization may be an important factor for skeletal muscle mass maintenance with aging.•Muscle fiber capillarization could be considered as an interventional target to support healthy muscle aging.