Hi Ryan! You might experience a small amount of stretching in the Glycerin StealthFit 20, however it will not stretch significantly. We do have a phenomenal return policy which allows you to try our gear out for your normal runs and walks, inside or outside. If they do not work, we offer free pre-paid return labels on orders to send them back within 90 days for worn items, and 1 year for unworn items. Even if you get them dirty or lose the box we can still take them back with our free labels via FedEx or USPS for a full refund.