Perceived effort vs. HR
 

Does anyone know why after a day off, its far easier to elevate my HR? While using the same gear on my mag trainer, my HR goes higher than average, with much less (perceived) effort than it does after several days of riding without a break. For example, to average 150-155 after three days without a rest, I'm really dogging it, grinding away at the gear and having to stand frequently. Today, after no ride yesterday, 155 and higher was effortless. Is this a good or bad thing?

Because your leg muscles are rested. They are the largest muscles in the body and they elevate the heart rate more because of their size. When rested they perform better and need more blood which forces the heart to deliver. When they are tired they don't perform and don't need as much blood.

There is nothing wrong if you reach higher rates with "less effort". You are rested and just think it is less effort.

There are so many variables that affect heartrate. Chronic dehydration, heat, air pressure, recent illness and blood volume are all possible causes of elevated PE at a particular HR. Many athletes have opted for power output measurement via a PowerTap, SRM, or Ergomo because of the inconsistencies associated with heartrate monitoring. IMHO, it is far better to compare RPE to chosen gearing and cadence (when riding your trainer) than to monitor heartrate. Did you ever notice that late into a trainer workout, your heartrate becomes easier to elevate? This is a result of fluid loss (dehydration). Don't necessarily ditch the heartrate monitor, it can still be used for very easy, endurance type workouts. As for threshold and above, train by power or simply RPE.

remember that your question is about total stress on your body, including your work, family related stuff.