Designing a tracking system for ordered workouts
Well, there's a simple 1 table solution right here:

| exercise_type (not null) | amount (not null) | other_field (null) | date (not null) | 


To get the exercises for a particular date, you'd run a simple select statement (psuedo code): 

select * from exercises where date in between (start, finish)


And you can refine to particular exercise types by adding:

and exercise_type = 'plank'