I am 42, i have high BP, but taking meds. I work out 3 to 5 times a week, i was jogging 2 to 3 X outdoors in the summer at about 2.5 to 3 miles a time. After 3 months of doing this consistantly, i still could not jog any faster and my heart rate would get very high and not get better. I would even climb a flight or two of stairs and felt like my heart is beating very fast. One Doctor said it was age and also issue with Cardio, but after 3 months of constant running, it wasn't any better. Some think it might be sports induced Asthma, someoene else said something about Allergies.