While running on a treadmill or other fitness equipment, a user can quickly build up a static electric charge. The static charge is generated by clothing rubbing against itself, contact from thigh to thigh or arm to body. It may also form from shoes striking the tread, especially if a shuffling action is happening. Depending on the clothing worn and humidity levels, a large static charge will build during the workout. The built up static charge seeks a path to discharge. The discharge path can be from any point on the user to any grounded surface. When a headphone is worn, the path may go from the user’s ear to the speaker in the headphone.
Why do headphones shock me when I'm working out?
The short answer is: they don't! The static discharge shock problem is not caused by the headphone jack or anything else on the treadmill not being grounded. Typically, just the opposite is true.
Electrostatic charges look for a path to ground in order to discharge. When a user builds up a large static charge, the charge is looking for a place to discharge to ground.
An example of this is in a building that has very low humidity with carpeted floors. When you walk across the carpeting, you will build up a static charge. When you reach for a light switch, a static discharge spark will occur between your finger and the screws on the face-plate of the light switch. This is because those screws are at ground and the static charge in your body is seeking to discharge itself to ground.
The same thing is happening on the treadmill. you've built up a large static charge. The headphones provide this path. The electrostatic discharge spark occurs from the inside of the ear through the sound opening in the earphone to the tiny speaker inside of the headphone through the headphone wiring to ground.
Looking for more advice to stop static on your treadmill or elliptical? Check out these 5 Tips for Managing Static Electricity in Treadmills, Ellipticals, and More!
Important Note: Due to the above, one might think that it would be better to not ground the unit and therefore eliminate the electrostatic discharge problem. This is not the case. If the unit is not grounded, dangerous problems could arise! Always have your fitness equipment installed by an expert. We are required to have the treadmill grounded in order to comply with safety approval agency requirements (UL and CE). If an electrical part were to fail and short out to the chassis, the grounded treadmill would prevent dangerous voltages from being exposed to the user.