u/Weekly-Energy-5284

Hello! For context, I started going to the gym in February and I go 4 days a week. When I first started, I could only do 3.0 mph on the treadmill with no incline and my heart rate would reach almost 200 bpm! (5’2, 148 lb, 19 y/o female) Now, I can do 2.5-2.8 mph with 15% incline and my heart rate peaks at around 180 bpm. (5’2, 136 lbs now!). My question is, does this mean that my heart health has improved? Or is it just my body getting used to the more intense exercise? Is this normal?