I was reading through this interesting post.
Recent research has shown that your body doesn’t see a significant increase in training benefits after running for 3-hours. The majority of physiological stimulus of long runs occurs between the 90 minute and 2:30 mark. This means that after running for 3 hours, aerobic benefits (capillary building, mitochondrial development) begin to actually stagnate or decline instead of getting better. So, a long run of over 3 hours builds about as much fitness as one lasting 2 hours and 30 minutes.
The post then goes on the suggest the concept of “accumulated fatigue.”
By adding a steady run the day before the long run, you can simulate late race fatigue without having to run the full distance and teach your body how to finish strong and fast.
Interesting approach. And one that may fit well with my schedule. It’s tough to squeeze in a 3 hour run. It may be easier for me to string a one-hour “steady run” followed by a much-longer run. in case I am lacking in motivation, I can actually signup for a 21K run and run a 10K the day before that event.