There’s no doubt running is a high-impact exercise, especially on hard surfaces like roads. This is why many people choose to use a treadmill, as treadmill running decks are usually equipped with a deck cushioning system to protect your joints. Sadly, some budget treadmills are not equipped with a deck cushioning system; these are the treadmills to avoid. Good budget treadmills can be found for under $400 with deck cushioning systems.