US 4,930,770 · Granted 1990-06-05
The Smart Gym Machine That Pushes Back (Or Pulls You Forward)
Imagine a weight machine where a computer controls how hard it resists you as you move through different positions. On the way down, it fights your muscles; on the way up, it can actually help push you. A sensor tracks where you are and how hard you're pushing, so the machine adjusts its resistance in real time.
The plain-English version
What it protects
The claim covers a computerized exercise machine where a motor-driven coupling system provides variable resistance that changes based on your position in the movement. What's protected here is the specific combination of: a variable torque motor connected through a torque coupler to the user's interface, position and force sensors feeding data to a processor, and that processor's ability to switch between resisting force (during muscle contraction) and assisting force (during the negative stroke) at any point in the range of motion.
Why it matters
This patent represents an early approach to what became known as accommodating resistance in strength training—the idea that a machine can intelligently match the difficulty of an exercise to your current position and effort. By using a processor to control resistance dynamically rather than relying on fixed weights or simple mechanical systems, it opened the door to more sophisticated fitness equipment that could adapt to individual users and different training styles in real time.
Real-world use
When you use a modern smart gym machine that adjusts resistance based on your movement speed or position, you're experiencing the core concept this patent locked down.
Original USPTO abstract
A processor controlled eccentrically loaded exercise machine for providing a resisting or powering force which can be varied by position in order to carry out positive or negative exercise strokes. A variable torque motor provides a torque to a torque coupler. The torque coupler is coupled to the user interface device through a mechanical link. During a positive exercise stroke, the motor supplies a torque to a slipping torque coupler so as to provide an eccentrically loaded resisting force, which resists the force exerted by the user in moving the exercising device as his muscle contracts. During a negative exercise stroke, the torque coupler engages to provide a powering force, as supplied by torque motor, against the contracted muscle of the user. A position sensor and a load cell are coupled to the user interface device for providing position and force signals to the processor. The processor, by controlling the motor torque and the torque coupling of the torque coupler, is capable of providing a resisting or powering force which can be varied by position for providing various modes of exercise available to the user, including the ability to immediately switch between positive-negative or negative-positive exercise at any position within the exercise machines range of motion.
Patent details
- Publication number
- US 4,930,770
- Filing date
- 1988-12-01
- Grant date
- 1990-06-05
- Assignee
- Baker Norman A
- Inventor(s)
- BAKER; NORMAN A.
- CPC class
- A63B21/157
Want to file your own patent?
Curious how today's fitness tech stacks up against older patents? Scan a new gym machine design through our free patentability checker to see what's already been claimed in the fitness space.
Free patentability scan