After a nasty crack up in May I got hundreds (~400) of miles behind on my training and as I had the STP coming up In Mid July I put aside all my best intentions of a one day 200 mile ride and went back to the back to back century.

I've 15 & 25 mile loops I ride 5 days a week and I began riding it pretty hard (for me). I'm 58 Y.O., 5' 10" and a solid 193. A resting heart rate under 60, usually 58-59 bpm (by way of a Holter monitor). Several years ago I began using the Karvonen heart rate formula and it is pretty accurate though my max heart rate is about 8 beats above my predicted (162). Where it is accurate is on the 75% VO2 which for me is at 136-137 and that's the transition from easy talking to clipped sentences.

In August I dug out my old Polar HRM, popped a new battery in what I discovered is I was frequently going above 80%-85% VO2. My 1/2 mile sprints had me up to 166 bpm in the blink of an eye. I was pedaling at 85-90 rpm, going fast, but I was always gassed. It should've dawned on me that I was constantly in glycogen burn zone, frequently hitting my lactic acid limit, backing off, hitting it again, occasionally bonking...but I hadn't put it all together. After one two week continuous daily ride session I realized I wasn't 21 and I'd probably have to rethink training. I was beat, tired, felt like training was unproductive.

Now I'm tight on not going over 75% during base training, still pedal at 85-90+ rpm and plan to stay this way for a month or so, then slowly add interval training back in end of year or next.

End result..I feel a lot better. In truth..I didn't really need the HRM and I had an inkling of what was going on. The HRM just confirmed it. Being in the fat burn zone means I'm not ping-ponging between fat burn and glycogen burn and that drove me nuts. Now my food intake makes sense and is not conflicted between what to eat before and post ride. Take home message is that training planning makes a huge difference and sticking to a schedule will (eventually) produce results. I admit missing those extra ~25 beats...that would've had me at a 75% VO2 at a heart rate of say 162....but I'm not 35 anymore either.

I came to similar conclusions. My MHR is around 160, and a typical week might include one 60+ mile ride at a slow or medium pace, and one 16 mile ride with 4-5 30 second intervals thrown in.

What is your reasoning for waiting a month or two before adding intervals back in?

T-Bone- I don't have a good reason other than wanting to solidify the base and not get crosswise with interval. Also...my best 1/2 mile interval spot is a beach approach road and once fall weather hits with force (today! Our first storm walked in)..,far less traffic. I've tried intervals on the MUP...not easy to do.