Treadmills provide a simple, effective aerobic workout. A staple of commercial gyms, treadmills have also become one of the most popular home exercise equipment machines. Despite their popularity, however, treadmills possess distinct disadvantages. In addition to the high cost and monotony of this type of exercise, using a treadmill in place of running outside may change your actual running form, decrease your overall efficiency and limit improvements in coordination and balance.

Cost

Treadmills cost money. While you can walk or run outside for free, the cost of a budget home treadmill ranges from about $300 to $700, as of 2011. However, many budget treadmills do not last very long or fail to give you the type of workout you need. High-end treadmills cost much more. The Life Fitness home treadmills, for example, range in price from $2,000 to $7,000. The initial cost of the treadmill does not include the additional costs associated with maintenance and repairs. Regular treadmill use requires oiling, belt replacement, and sometimes replacement of the entire motor. In addition, motorized treadmills increase your home electricity bill.

Monotony

Working out on a treadmill can get boring quickly, particularly if you repeat the same workout routine day after day. The scenery does not change, which affects the psychological satisfaction that comes from running in new locations, particularly in environments free from the distractions of home. In addition, some treadmills emit relatively loud and monotonous noises, which can quickly become irritating. Because of this, many treadmill users lose interest and stop working out altogether.

Biomechanics

Running on a treadmills does not exactly mimic outside natural running. Wind resistance increases your workload between 2 and 10 percent, depending on how fast your are running. More experienced runners may have longer strides when running on the treadmill, whereas inexperienced runners seem to have the opposite results. Some treadmill runners tend to spend more time on their support leg compared to running outside. This decreases their efficiency. The posture of some runners also changes. When on a treadmill, some runners appear to lean forward slightly less than when running outside. This causes them to waste some of their energy on an up and down motion, rather than focusing on forward momentum.

Loss of Ancillary Benefits

Running on a treadmill allows you to run on a consistent surface area. You will not encounter obstacles, such as stones, soft or hard areas, wet or dry areas or other combination surfaces. While this may seem like an advantage, challenging your body to run over these surfaces improves proprioception, or the ability to sense where your body is in relation to its surroundings. Challenging or simply just changing surfaces helps build coordination among your brain, muscles, body parts and joints. Coordination and perception of your body in space affects balance and power. Treadmill running lacks this important benefit.