Curved treadmills are manual machines that have no motor and need no electricity. The treadmill belt is propelled by the motion of your own body. Curved manual treadmills go as fast as you go, which feels more natural than the fixed speeds of motorized treadmills. 
 
The reason curved treadmills are unique boils down to their unique U shape, which may limit joint stress while keeping your form in line.
A curved belt is designed to follow the arch of your feet travels throughout the running stride. This shape may reduce joint impact and facilitate a more natural feel while you keep your running form efficient.
 
They’re also completely green, so you won’t have to worry about finding a plug or racking up a massive electric bill. Because they have no motorized parts, curved treadmills are low-maintenance machines. Their non-motorized slatted belts are much more durable than traditional treadmill belts. They won’t need constant adjustment or lubrication.
 
Why Curved Treadmill? 
1. Burns More Calories
2. Higher Heart Rate & Oxygen Consumption
3. More Intense Workouts - Ideal for HIIT and Sprints
4. Works More Muscle Groups
5. Less Joint & Knee Pain
6. Improves your Form - Easier to run on the balls of your feet like a true athlete!
7. Less Maintainence 
8. Environmental Friendly