Atrophy.

 What do you do to stop it?  What do you do to reverse it?

In the beginning of Spring Quarter, 1993, I tore my left ACL.  A few weeks later, in April, I had surgery to replace the torn ligament.  I spent two months on crutches, as well as months with various braces, wraps, and supports.  Months of physical therapy ensued to rebuild, both the replacement parts and the surrounding and supporting bits that had shrunk while not being used.  By the end of the summer, I was cycling with a brace.  By the Fall, I was able to play a bit of volleyball.  For years, my mom would say that my left leg was thinner than my right.  Still atrophied, but improved.

In the late 90s, I started running.  Kept cycling.  Since then, I've continued to run and ride.  I've had a few injuries that have sidelined me, forced me to take time off.  Sometimes, those injuries have involved physical therapy to recover, often exposing various muscles that were weaker than those around them.  Exercises to build up the weak muscles and recover from injury, allowing the running and riding to continue.  

Lots of things atrophy.

Muscles.

Memories.

Technical skills.

Years ago, I did system administration work.  MacOS, Solaris, Windows.  Troubleshooting methodology remains, but certainly not the details.

Later, I did a number of storage related tasks -- SAN, NAS, WAFS.  Installation, configuration, benchmarking, troubleshooting, tuning.  Could I tell you how to set up a port-to-port zone configuration with the storage, switches, and HBAs that we used?  No, I'd have to review the documentation and spend some time coming back up to speed.  Some of the methodologies remain with me today -- that zoning restricts where the traffic goes, less noise is good, dedicated signal is good, don’t bend the fibre cables too much.  Benchmarking ideas and methodologies.  

How do you pick which skills are important to maintain?  How do we maintain those that aren't part of the day to day?

In school, I learned a bit of lisp, ml, and a handful of others for a comparative languages course.  I spent at least a quarter in Fortran, Pascal, 3b2 assembly.  

We learned assembly.  I knew assembly – registers, stacks.  I don't know assembly now.  I don't know those other languages either.

I've spent years in each of Java, Perl, C++.  Programming.  Algorithms are still algorithms, speed still comes from understanding O(n) is better than O(n ln n) is better than O(n**2).  The language specifics fade out.  

How do you hold on?  What do you hold on to?

For running and cycling, for these physical activities, it’s easy.  Full body workout, emphasis on the supporting muscles for the primary pursuits of running and cycling.  Don’t neglect the weak areas.

For technical areas, it's a little harder.  Algorithms, TDD, Scrum, these can follow to the new pursuit.  

How do you maintain, how do you know which are important to hold on to?

Atrophy happens to everyone, in lots of ways.