The typical initernet medical advice cautions apply, but I experience the same/similar syndrome each year as I begin to ramp up intensity after a long winter on the computrainer doing zone 1-2 time. At first the base intensity is so easy after riding outside all summer, then as the miles pile on I get to the point that the legs feel heavy, leg speed drops and small hills or a sprint will send HR sky high and power levels are much lower than what I would expect given RPE. I often wonder how I could have possibly produced my FTP last summer as now I can get there but holding it for more than a few minutes is close to a near death experience.


Then as I start to introduce more intensity, such as intervals or I follow Friel and he has you do tempo time trials 3 miles at 10 beats below LTHR or about low zone 4 HR so intense but something that is typically done easily during summer quite often. These are done 3 weeks apart and the first one feels like I am going to explode by the end. Second, I hit same power and HR levels but the effort came much easier and HR does not jump up as quickly.


The past month I graduated over/under threshold intervals, supposed to do 4-5 @6-8 minutes. I could only do 3 before my legs and lungs on fire and HR was thru the roof. Next one was much better, able to complete set and felt like I wanted more and HR slightly lower levels but did not ramp up as fast.


In short, your body detrains a bit during all ofthe low intensity work during the winter, it does not handle lactate efficiently because it has not seen it for a long time. As it gets used to lactate, your HR should not ramp up quite as quickly and RPE should also decrease for same effort. I also find that handling changes in pace are much more difficult after spending months doing steady state training for he same reason.