Questions & Answers about Efter träningen känns armen och benet bättre.
Because träningen is the definite form: the training / the workout.
- träning = training, exercise, practice
- träningen = the training, the workout, the practice session
In this sentence, it usually refers to a specific workout or training session, so the definite form is natural.
Also, Swedish often puts the definite article at the end of the noun:
- en träning = a workout
- träningen = the workout
This is because of the Swedish V2 rule: in a main clause, the finite verb usually comes in second position.
Here, Efter träningen is placed first. That means the verb must come next:
- Efter träningen
- känns
- armen och benet
- bättre
- armen och benet
- känns
If you start with the subject instead, the order changes:
- Armen och benet känns bättre efter träningen.
So the meaning stays basically the same, but the word order follows Swedish sentence structure.