When my first pregnancy became obvious, a Nike teammate congratulated me and told me not to worry about 'bouncing back' since muscles have memory. Coach was standing by, he growled, "that's precisely the problem". One of the assistant coaches explained what he meant in a little more detail, which is worth sharing.
The biggest danger to runners recovering from injury and pregnancy are their muscles. Muscles have memory; you will get them back to former levels before your joints and ligaments are equally adapted; the (scientifically-based) rule of thumb is 8:1 in 30-40 year old runners. So runners who have been fast at some point in the past and who are used to reading their effort levels will have a false sense of confidence about their current abilities.
My former (pre-2010) 5k pace was 5:20. My muscles know that pace. They instinctively go there in pickups. My brain knows ain't NO way I'm running a 16:30 5k in the near future. My brain also knows that 5:20 is way too fast for speed development for me right now, it just puts unnecessary stress on my cardio system, so much that my benefits are limited: I left this workout no better off than before speed-wise. My brain is no closer to being synchronized with my muscles in the way it needs to be in order to become faster over the long haul. It is going to take awhile to adjust to this new normal, so I just have to be patient. Imagine I'm a professional runner who needs race money to pay my mortgage: today's workout would be viewed as a total failure. Thank God I'm not elite!
So if you are post-partem or recovering from injury, THIS is precisely why I need you hitting the lap button on your pickups. The familiar to your muscles is probably too fast for your joints today. Everyone else: you don't have this problem so go congratulate yourself on not needing the lap button errrrday.
#coachedandloved