PHYS-41 · Principle
How much fitness do I lose on a two-week holiday?
A little. In trained athletes who stopped completely, VO2max was a few per cent lower after two to three weeks, much of it lost blood volume, and strength held longer.
How the body works, agreed across the reviews below; a study entry shows what one experiment measured.
Practical Application
How much fitness do I lose on a two-week holiday? A little. In trained athletes who stopped completely, VO2max was a few per cent lower after two to three weeks, much of it lost blood volume, and strength held longer.
Mechanism
Within 4 weeks highly trained athletes lose VO2max and blood volume quickly, maximal cardiac output falls, and capillaries and oxidative enzymes are already reduced, while strength changes little (REF-374).
In small single studies VO2max was 4-7% down at 12-21 days and 10-20% by 5-8 weeks, then levelled off (REF-1133).
Beyond 4 weeks long-trained athletes stay above untrained values; recent gains are lost entirely (REF-374).
Common misreading
"Two weeks off and it is all gone", and the reverse, "muscle memory means nothing is lost".