That can be a tricky question. If you're coming off an end of the season peak and launching into base training, you might not see your pre-layoff race shape return until next season. However, in the meantime, you won't lose too much in two weeks along the line of aerobic conditioning and will probably find within a week or two that you're back to normal and ready to push on to higher levels of fitness in that regard. Just remember, you don't need to be in race shape until your next racing season. In the meantime, you can prepare to make the most of that season by working on your aerobic base.