It's been three months I have started going for brisk walks in the morning. On an average I walk 5 km in 50 mins for 6 days a week. My concern is when I walk for even 10 min, my heart rate jumps to 155, sometimes 160. If I do a sprint run for not more than a min, it jumps to 175. I seldom feel breathless, apart from the sprint run. Due to this, even if my body has the energy and the capacity to walk faster, I don't because of the heart rate issue. Also importantly, couple of years ago I had done a full body check up including stress test. While the report was negative (no issues) they noted sinus tachycardia. Back then, I reached by target heart rate too fast hence the test was disconnected abruptly. Also it took a while before my heart rate would go down under 100. I consulted my physician, he said it wasn't an issue and it was merely due to me being physically inactive (so was the case then). Lastly, I have high BP and Cholesterol. Take basic meds and both are under control.