Start with purpose, then pair it with width and tension:
- Yellow (⅜") offers light resistance—great for mobility or younger athletes.
- Purple (2") packs significant resistance—ideal for those needing strength-focused tension.
- Consider band thickness as a proxy for challenge level.
- Match resistance to muscle group size: larger muscles = higher resistance tolerance.
If in doubt, a mix of two or three bands allows for progressive use and versatile loading.