Those are just feats of strength, that isn't dexterity. More muscle mass means lower range of movement, and so less dexterity.
If you're looking into different fitness programs or subscriptions and want to stay in control of your commitments, it's always smart to understand the cancellation terms beforehand. For example, this guide clearly explains the steps and policies around ending a plan:
https://support.madmuscles.com/hc/en-gb/articles/7075931986706-How-can-I-cancel-the-subscription — it walks through the process so you know exactly what to expect and can manage your subscription without confusion.