Since AssaultBikes use air for resistance and the resistance level increases as you increase your effort level, they can provide a more challenging workout than some other types of exercise bikes. As you pedal with your legs and move your arms, the bike's large, integrated fan begins to spin and create resistance as the blades work against the air. The faster you pedal and push and pull, the faster the fan begins to spin and the greater the resistance created. Additionally, AssaultBikes engage both your upper and lower body, which is different from regular cycling and running and means you may tire more quickly than you would if you were only using your lower body.