Thanks for the Snowy photo... very nice.
I recently came across a couple of articles I thought you might find interesting, probably of more value for your wife, given the way she trains and competes.
"Too much exercise can kill you. The Haywire Heart is the first book to examine heart conditions in athletes. Intended for anyone who competes in endurance sports like cycling, triathlon, running races of all distances, and cross-country skiing, The Haywire Heart presents the evidence that going too hard or too long can damage your heart forever. You’ll find what to watch out for, what to do about it, and how to protect your heart so you can enjoy the sports you love for years to come. Read more here
And, from this site
considering efficiency- If a rider can improve efficiency then they can produce more power for the same effort (oxygen consumption). The secret is shorter cranks.