Treadmill vs. Land Walking/Running

Question:

In what way is treadmill walking/running different than moving on land? Are there dangers involved with treadmill use, and what muscle imbalance might result from continued use of treadmills in training?

Answer:

In what way is treadmill walking/running different than moving on land?

• When walking/running on land, the mind and body will have to contend with some environmental specific conditions; for example, the hard surface, the natural camber of roads (slight inverted "U" shape to help water drain from the road), other traffic (having to weave through other people or cross roads) and wet slippery terrain.
• Conversely, when on a treadmill, the mind and body must contend with a confined movement space, belt lag (see below), vibration (see below) and possible boredom.
• From a mechano-physical point of view, at a normalized pace, the rearward rolling tread decreases the need for the hamstrings to pull the upper body forward; however, the hip flexors now have to work harder to control the foot being dragged backwards (eccentrically) and in pulling the lower leg forward (concentrically). A decrease in push off ability (caused by the moving belt) further increases the hip flexor load.
• The machine sets a selected pace that is unchanging in light of indirect factors (e.g., headwind, terrain changes etc). With this in mind, the mental concentration required to maintain a running pace is reduced. For this reason, many who tend to train to a greater extent on a treadmill have difficulties in applying the same speed to the hard surface. They may not have developed the mental fortitude to maintain a pace, and as their mind wonders, their pace decreases.
• The skeletal (bone) impact may be less on the stride machine as there is a flexible striding surface located underneath most stride belts cushioning the impact.
• In terms of energy usage, most research at this stage suggests that there is no significant difference between treadmill and land surface running.

Are there dangers involved with treadmill use?

• Believe it or not, one of the highest injuries from treadmills comes from falling off. And while beginners are at a greater risk, often experienced runners suffer the same fate. Some hints to prevent falling off:
  • Ensure shoe laces are well tied.
  • Ensure that any water bottles, mobile phones and towels placed on the machines are well secure and will not vibrate loose and fall onto the moving belt.
  • Avoid looking at yourself in the mirrors while running.
  • Always look straight ahead. This includes when talking to friends or watching television (If in a cardio studio, select the treadmill directly in front of the channel you wish to watch).
  • Learn how to mount and dismount a moving belt (use the scooter method). You may think "I will just slow or stop the belt," but sometimes this may not be an option.
  • Avoid altering your natural walking/running gait (e.g., holding a mobile phone to one ear while moving). A slight weight shift and body drift on land is fine, but on a moving treadmill, it can cause problems.
  • Most importantly, know your machine. If you do not, ask.
  • If the machine has a safety device that clips onto clothing to decelerate the belt in case of falls, use it. If you don't, know where the emergency stop button is.
• As with any form of training, overuse injuries are of concern. If possible, intersperse the treadmill with land-based walking/running or alternate with other cardio machines. Variety helps prevent pattern overload injuries.
• Natural gait and correct body alignment can also be adversely affected. The undesirable alterations in gait techniques can be caused by inexperience, an incline which is too steep or a pace which is too fast (or even slow). Body alignment and posture can likewise be compromised; for example, by holding onto the rails with an incline that is too steep or a belt travelling at too high a speed. Both of these factors alter correct force transfer along the body and increase the force placed through the joints and muscles.

What muscle imbalance might result from continued use of treadmills in training?

• This is truly individual and depends on numerous factors, from the individual’s technique and previous injuries to training speed and brand of treadmill.
• Thus, in order to prevent muscle imbalance, as alluded to above, variety is the key. Either alternate training surfaces or cardio machines. If only treadmill training is available, alter the training methodology on the treadmill (Interval, Fartlek and Long Slow Distance, Inclines, Speed etc).

Additional Considerations

• Belt lag. When the foot strikes the treadmill belt, the force through the limb is transferred to the belt, which is travelling in the opposite direction. This impact force causes the belt to stop momentarily (even reverse direction slightly) before belt speed is reinforced by the motor. The amount of belt lag varies with the power of the motor, looseness of the belt, belt speed and weight of the individual. The effect on the body is yet to be scientifically studied; however, the sharp, reverse-direction acceleration, for a high repetitive duration, may not be complimentary to the body.
• Vibration. The smaller and lighter the treadmill, the more the vibration (especially at the higher speeds). This can be clearly felt when running on a cheaper domestic treadmill compared to a more expensive industrial treadmill. I have found no research regarding a treadmill specific effect; however, whole body vibration (albeit over a long period, like truck driving) has been linked to lower back problems.
• Cleaning agents used/old belts. Cleaning agents (I have seen belts cleaned with furniture polish) or old tread-worn belts may cause the belts to become slippery.