Portable and variable exercise device
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.
1. An exercise device comprising:
a cable;
a force modulating pulley around which the cable is wound; and
a constant force spring engaged to the force modulating pulley, wherein the constant force spring provides a constant resistance against rotation of the force modulating pulley when a force is applied to the cable;
wherein the force modulating pulley varies the force that must be applied to rotate the force modulating pulley when the force is applied to the cable;
wherein the force modulating pulley includes raised threads separated by valleys;
wherein the cable is engaged to the force modulating pulley within the valleys;
wherein the valleys have a varying diameter forming an hourglass profile extending between ends of the force modulating pulley along an axis of the force modulating pulley,
wherein a minimum diameter of the hourglass profile is at a mid-point between the ends of the force modulating pulley along the axis; and
wherein the threads have a constant diameter along the axis.
2. The exercise device of claim 1 , wherein the constant force spring is wound around a preload pulley that rotates about a first axis.
3. The exercise device of claim 2 , wherein the constant force spring is wound around a storage pulley that rotates about a second axis.
4. The exercise device of claim 3 , wherein the constant force spring is a flat wound spring with a preload section engaged to the preload pulley and a storage section engaged to the storage pulley.
5. The exercise device of claim 4 , wherein as the force modulating pulley rotates, more or less length of the constant force spring passes from the preload section to or from the storage section, depending on a direction of rotation of the force modulating pulley.
6. The exercise device of claim 2 , further comprising cartridges that increase the constant resistance against rotation of the force modulating pulley when the force is applied to the cable.
7. The exercise device of claim 6 , wherein the cartridges each comprise a cartridge constant force spring engaged to a cartridge preload pulley that is engaged to the preload pulley to increase the constant resistance.
8. The exercise device of claim 7 , wherein the engagement between the cartridge preload pulley and the preload pulley is a non-slip engagement.
9. The exercise device of claim 6 , wherein the cartridges each comprise a constant force spring engaged to one another in an engagement that further increases the constant resistance.
10. The exercise device of claim 1 , further comprising a protective housing through which a portion of the cable extends.
11. The exercise device of claim 10 , further comprising a cable stop that prevents the cable from being drawn into the device beyond a location of the cable stop.
12. The exercise device of claim 10 , further comprising a handle configured to be attached to an anchor.
13. The exercise device of claim 12 , wherein the handle is configured as a clamp.
14. The exercise device of claim 1 , further comprising a housing that contains the force modulating pulley and the constant force spring; wherein a first portion of the cable is inside the housing and a second portion of the cable pulley is outside the housing, and the housing comprises a slot through which the cable extends from inside the housing to outside the housing.