Researchers studying 353 cognitively unimpaired adults aged 60 to 94 found that higher muscular capacity was associated with lower basal ganglia perivascular space volume, while greater aerobic fitness was associated with greater gray matter volume and medial temporal lobe thickness. Fitness was not directly associated with global cognition or episodic memory, and evidence for cognitive reserve was limited, although VO₂max explained additional variation in delayed verbal memory beyond tau burden.