Variable Resistance Exercise Device Using Helical Pulley
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Solution Overview
Problem
Conventional strength training devices apply fixed resistance throughout the range of motion, failing to match the natural length-tension relationship of skeletal muscles, thereby under-stressing the middle range and over-stressing the ends, which limits effective muscle strengthening and increases the risk of injury.
Innovation Solution
A portable exercise device with a main interface mechanism incorporating a pulley, cable, constant force spring, and interchangeable resistance cartridges that modulates resistance to mimic the natural length-tension curve of muscles, providing variable resistance for concentric and eccentric contractions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If fixed resistance is applied throughout the range of motion, then the device structure is simple, but the muscle strengthening effectiveness is reduced because it does not match the natural length-tension relationship
Solution Approach 1:
The patent applies the dynamics principle by replacing fixed resistance with variable resistance that changes throughout the range of motion. The resistance mechanism dynamically adjusts based on the muscle's position, transitioning from high resistance at the ends of ROM to low resistance in the mid-range, matching the natural length-tension relationship and maximizing muscle strengthening effectiveness.
Solution Approach 2:
The patent implements parameter changes by varying the resistance force parameter throughout the range of motion according to the length-tension curve. The resistance is set to be highest at the ends of ROM and lowest in the mid-range, directly changing the resistance parameter to match physiological muscle characteristics and improve strengthening effectiveness.
2Ease of operation
If fixed resistance is applied throughout the range of motion, then the device is easy to operate, but the middle range of motion is under-stressed while the ends are over-stressed
Solution Approach 1:
The patent applies dynamics by making the resistance force variable rather than fixed. The resistance dynamically adapts to the muscle's position in the range of motion, providing appropriate stress levels at different phases of movement. This dynamic adjustment ensures reliable muscle stress distribution that matches physiological requirements, preventing both under-stress in the mid-range and over-stress at the ends.
Solution Approach 2:
The patent implements parameter changes by adjusting the resistance parameter throughout the range of motion according to the length-tension curve. The resistance is set to be highest at the ends of ROM and lowest in the mid-range, directly changing the resistance parameter to match physiological muscle characteristics and improve strengthening effectiveness while ensuring proper stress distribution.
3Productivity
If variable resistance matching the length-tension curve is implemented, then muscle strengthening is maximized, but the device complexity increases
Solution Approach 1:
The patent implements parameter changes by varying the resistance force parameter throughout the range of motion according to the length-tension curve. The resistance is set to be highest at the ends of ROM and lowest in the mid-range, directly changing the resistance parameter to match physiological muscle characteristics and improve strengthening effectiveness.
Solution Approach 2:
The patent applies mechanics substitution by replacing complex electronic or computer-controlled resistance systems with a purely mechanical resistance modulation mechanism. The mechanical system uses springs, pulleys, and cam mechanisms to automatically provide variable resistance based on the length-tension curve, achieving muscle strengthening effectiveness without requiring complex electronic controls.
4Device complexity
If conventional fixed resistance equipment is used, then the device is portable and simple, but it over-stresses the ends of the range of motion increasing injury risk
Solution Approach 1:
The patent applies the dynamics principle by replacing fixed resistance with variable resistance that changes throughout the range of motion. The resistance mechanism dynamically adjusts based on the muscle's position, transitioning from high resistance at the ends of ROM to low resistance in the mid-range, matching the natural length-tension relationship and maximizing muscle strengthening effectiveness.
Solution Approach 2:
The patent implements beforehand cushioning by designing the resistance mechanism to automatically reduce resistance at the ends of the range of motion before excessive stress can cause injury. The variable resistance system provides lower resistance at the extreme positions, cushioning against excessive loads that could damage muscles or joints, while maintaining adequate challenge in the mid-range.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The device effectively challenges muscles throughout the entire range of motion, maximizing strength development by matching the natural force curve of muscles, reducing the risk of injury by evenly stressing the muscle fibers.
Implementation Method 1
a constant force spring (240) mounted on a preload pulley (242a) and a storage pulley (242b)
Implementation Method 2
a force modulating pulley (230) with a helical thread (232) thereon between which the cable (210) winds
Implementation Method 3
a force modulating pulley (230) with a helical thread (232) thereon between which the cable (210) winds
Data Source
AI summary
The apparatus provides an exercise device that is portable, versatile, and enables the user to match the resistance of the device with the normal physiologic length-tension relationship of skeletal muscle. The device adds resistance in the form of cartridges that are stackable to summate resistance and can connect to a variety of attachments for use with arms, legs, or trunk, i.e., handle, bar, loop, etc. Given the device's portability, it can be used freestyle or mounted to various surfaces.