• Some exercise machines are harmful and potentially dangerous.man exercising on treadmill 6 image by Ken Hurst from Fotolia.com
  
  Exercise has become an incredibly specialized activity with dozens or even hundreds of different machines to isolate muscle groups and perform different functions. While many of these machines are invaluable training aids, some are useless and a few are actually harmful and potentially dangerous. Do your research and learn to separate the useful ones from the useless or harmful ones.
  
  

Treadmills

• Treadmills may seem like a safe and convenient way to improve your cardiovascular health, but they are potentially very dangerous -- particularly for children. According to the New York Times, children may be tempted to touch the moving belt, causing serious and even disabling friction burns. In extreme cases, children can be pulled under the treadmill and killed. Adults can also be hurt or seriously injured if they fall on a treadmill without having the safety clip attached to their clothing. If you own a treadmill, always use the safety clip and never allow young children near it.
  
  

Hip Extension

• The hip extension machine is a selectorized weight machine which is supposed to strengthen the hip by having you extend your leg out behind you against resistance. Although this machine is supposed to strengthen the hips and glutes, it can actually increase damaging muscle imbalances if your hamstrings are tight or overactive, according to Askthetrainer.com. Use lunges, squats, step ups and other functional leg exercises to activate your glutes safely.
  
  

Lower Back Extension and Crunches

• On a lower back extension machine, you lean back against resistance, taking all of the force on your lower back. Although strengthening core muscles (including back muscles) is good for your body in general, this machine is potentially quite damaging. The lower back is fragile, and can be injured by the heavy load that the machine puts on it. According to Askthetrainer.com, using one of these machines is like lifting a heavy object using your back instead of your knees.
  
  Using machines to do crunches with added weighs is also damaging. Rather than training your abs to hold your body upright and strong, these machines can overwork your abs, leading you to slouch. Use plank pose or stabilization exercises for a healthy ab workout.
  
  

Standing Calf Raises

• A standing calf raise machine puts a heavy weight on your shoulders as resistance. You then raise and lower on your toes to strengthen your calves. The problem? Your calves can safely handle a lot more weight than your spine can. According to Men's Health, doing standing calf raises with all of that weight on your shoulders causes unnecessary spinal compression and puts you at risk for injury.