There can be a number of reasons for a sudden drop in one of your scores, but in the vast majority of cases it is because the exercise mix changed from the previous week.

We currently use the exercise mix from the most recent week to calculate your Strength Score. If you stop doing a key exercise, like barbell bench press, and shift to doing dumbbell bench press instead, this can more dramatically impact your chest score for the week.

In a certain respect, this reflects the reality of shifting over to a new exercise, where you'll initially pick lower weights as you're getting into it, or in some cases don't yet have the neuromuscular adaptations for that new exercise yet, compared to the one you were doing before.

If you stick to the new exercise consistently for a few weeks, you should find that this generally evens out, but in the shorter term you'll likely notice larger swings when you make changes to some of the key exercises in your workouts.

As with the first point, this should be addressed with the volatility update, so that your score won't bounce around as much when you make changes, along with us making the explanation text clearer in cases where this happens.