Will Training at 90 % max thicken the heart wall ?

Quoted post said:

Originally Posted by knight987 [IMG]/img/forum/go_quote.gif[/IMG]

I used to race road and MTB until I injured my back. Eventually the back deteriorated and I ended up not riding a bike for some years. I have decided to try again which means going through surgery. At the moment I can do 15 mins without too much of a problem so I do this on a turbo. I ride at 90 rpm with my heart rate reaching 90% max by 12 mins and sustaining >90% till end of ride. I remember years ago being told that training at such a high intensity will thicken the muscles around the heart and prevent the heart from increasing in volume. Is is true ? If so, what is the solution for someone riding for 15 mins a day who wants to get fit again?

No, riding at a hard pace but one that you can sustain for 12 minutes or more is not a bad thing and will not limit the heart volume increases folks typically see when starting a regular exercise training program. If you can sustain it for more than 8 to 10 minutes then you're talking about Threshold work at most and that's the bread and butter for a lot of folks around here who use a lot of sustained intervals in the 15 to 30 minute range like the classic 2x20 set as the foundation for their harder days.

I remember the capillary bursting theories and some other long since debunked nonsense about holding off on harder riding but the heart wall thickening one is news to me. I'm not a big fan of true HIIT programs as very short and very intense intervals to jump start fitness that some folks like but the sustained work you describe can be very useful. Personally I work it into a bigger program that includes some longer easier days in the schedule and a fair amount of mid distance Tempo to Sweet Spot riding but the Threshold work is not going to hinder longer term gains.

-Dave

you also get less blood pressure for a body that is under constant exercise,