As the title suggests I need some help with my heart rate. After about 20-30 minutes of off road riding my heart is thumping quite strongly, I can feel it in my throat and makes riding any further quite uncomfortable and sometimes painful especially in my throat. 
I only get to ride properly once a week but I am fairly active in my job 5 days a week. It's getting to the point where I don't want to ride because of it. When riding on the road I am fine for atleast 45 minutes but any longer and it starts.
I don't want to push it for fear of overworking my heart. I know I am unfit and also being underweight definitely makes it harder (22 yrs old, 5ft 7 tall and weigh 8.5 stone) Is it just a case of getting on the bike more often or is there more to it? I do have a turbo trainer that I don't really use, would it help having a spin on that and getting a heart rate monitor?
Any advice will be greatly appreciated
	
		
			
		
		
	
			
			I only get to ride properly once a week but I am fairly active in my job 5 days a week. It's getting to the point where I don't want to ride because of it. When riding on the road I am fine for atleast 45 minutes but any longer and it starts.
I don't want to push it for fear of overworking my heart. I know I am unfit and also being underweight definitely makes it harder (22 yrs old, 5ft 7 tall and weigh 8.5 stone) Is it just a case of getting on the bike more often or is there more to it? I do have a turbo trainer that I don't really use, would it help having a spin on that and getting a heart rate monitor?
Any advice will be greatly appreciated
 
				 
 
		 
 
		 
 
		 
 
		 
 
		
 
 
		 
 
		 
 
		 
 
		
 
 
		 
 
		 
 
		

 
 
		 
 
		