It is not uncommon to see your Training Deficit/Surplus increase over one day or sometime even a few hours. Training deficit depends on your activities in the past week. Activities don’t accumulate continuously. The deficit calculation is based your Improvement Rate and takes into account your activities from the past week. Sometimes activities enter and exit the moving window of consideration and can influence the training deficit.
In managing your activities, it is important not be too concerned with keeping the deficit at 0 but to maintain your Training Pacer on-track. It’s acceptable to train with a surplus and it is also acceptable to wait if you have a deficit, so long as you keep your training consistent and your maintain the pacer on-track.
For example, if the previous weekend, you managed to get out on a long weekend club ride at 8am that generated 400XSS points, your Training Load increased dramatically at 8am since that’s when the activity’s XSS will get counted. Starting Thursday to Saturday, you’ll see a higher than expected steady, hourly increase in deficit (or decrease in surplus) to give you an awareness that you’ll need to boost your training to maintain your improvement relative to the Training Load you had reached after that ride. The Adaptive Training Advisor performs some smoothing so that you don’t immediately see a large deficit at 8am the next Saturday.
Remember that any planned activities that you have planned within the next 24 hours will influence the secondary pointer on the Training Pacer.