PELVIC FULCRUM SUPPORT

Description

CROSS-REFERENCE TO RELATED APPLICATION(S)

The present application is a continuation-in-part of U.S. application Ser. No. 19/295,306, filed Aug. 8, 2025 in the United States Patent and Trademark Office, which claims priority to and the benefit of U.S. Provisional Application No. 63/733,937, filed Dec. 13, 2024, the entire content of both of which is incorporated herein by reference.

BACKGROUND

1. Field

The present disclosure pertains to a lightweight, easily portable, inexpensive device that allows an individual to perform, conveniently in any location, isometric back extensor core muscle exercises without the assistance of another individual.

2. Description of the Related Art

Lower back pain is a common affliction for all adults. The CDC reports that in the year 2022, 28% of adults experienced significant lower back pain. As we get older, it is more common to have lower back pain and with above the age of 65, 45.6% experience back pain. NIH reported in 2006 that 10% of all lower back pain is chronic. In 35% to 45% of all individuals with chronic low back pain, the etiology is secondary to facet arthritis. The facet joints link the vertebral bodies of the spine allowing bending and twisting. A review of the literature indicates that individuals with chronic lower back pain commonly exhibit deconditioning of the lumbar spine extensor muscles (i.e., multifidus and erector spinae muscles), characterized by reduced strength and endurance, muscle atrophy, and increased fatigability. These factors contribute to greater spinal instability that leads to pain. (Refs. 1, 2, 3, and 4) The third most common visit to a physician is lower back pain. Treatment and prevention of lower back pain is a major issue worldwide, not only for morbidity, but also secondary to lost wages and indemnity claims. Physical therapy is a mainstay in the treatment and prevention of lower back pain. In particular, core strength is at the root of the exercises performed in physical therapy. Anterior abdominal strength and posterior paraspinal, gluteal and hamstring strength are cornerstone. Since core strength is the mainstay of treatment, different techniques have been developed to strengthen the abdominals as well as the back, gluteal muscles, and hamstring muscles, thereby dynamically stabilizing the spine, pelvis and facet joints. Unfortunately, it is difficult to strengthen the lower back, especially in the setting of facet joint arthritis, and the physical therapy is typically performed in a clinic rather than in the home. Irritation of the facets can occur while attempting to perform strengthening exercises. These exercises must be carefully designed so as not to irritate the facet. Motion of the facet while performing a strengthening maneuver can lead to spasm of the surrounding muscles resulting in debilitating pain. Strong core muscles, essentially stabilize the facet joints, which mitigates against spasm and pain (Ref. 5).

Isometric exercises are a mainstay in physical therapy for strengthening of any arthritic joint. The joint is maintained in one position, while the muscles around the joint contract against force. A major cause of back pain and spasm is when a facet joint shifts while performing a lifting maneuver. This occurs more frequently, especially in the setting of degenerative disc disease with facet arthritis. Strong core muscles, stabilize the facet joints and mitigate against spasm and pain. Strengthening the core muscles has also been found to be highly beneficial in the setting of “nonspecific mechanical low back pain”, (Ref. 6) which the World Health Organization in June 2023 listed as the most common presentation of lower back pain, estimated at affecting over 550 million people worldwide. In a classic study of 928 individuals in 1984, weakness of the lower back measured by isometric testing and endurance, was found to be an excellent predictor of eventual and/or persistent back pain. (Ref. 7) This was further corroborated in another large prospective study of 508 individuals. (Ref. 8)

One fundamental core muscle strengthening exercise that can be performed at home is a plank exercise. The plank position with the body held in a prone straight line (like a plank of wood) is one of the best positions for isometric exercising for core strengthening. The classic plank exercise is held in a push-up-like position with the body's weight borne on the forearms, elbows and toes. In 2015, the five branches of the United States military instituted the plank exercise for back and abdominal strengthening, no longer utilizing the sit up exercise. However, the classic plank exercise is limited in force since the weight of the torso is supported mostly by the upper extremities. Various devices have been developed to help an individual perform the plank exercise but there are still limitations to this exercise due to lack of efficiency, effectiveness, safety, and portability.

One such device for performing plank isometric exercises is described in Domesick, U.S. Pat. Pub. No. 2023/0048498 A1. This device “has a hand grip and a frame extending from the hand grip. At least one arm support pad is connected to the frame, where in a distance between the hand grip and at least one arm support pad is adjustable. A ground—interface surface is positioned along, at least a portion of the frame.” The device is designed to help the individual position in a prone position with the forearms secured in the device by gripping the frame. While the device is portable, the disadvantage is that it does not allow the hands to be free for exercises such as lifting of weights to add additional force/work for the core muscle groups.

Another such device for assisting an individual to perform a plank exercise is described in LaFrance et al., U.S. Pat. Pub. No. 2021/0023414 A1. “A person may rest a portion of their body on cushions of the horizontal bars, so as to alleviate a portion of the weight associated with performing the plank exercise, and to help provide balance and stability while performing the exercise.” As with Domesick U.S. Pat. Pub. No. 2023/0048498 A1, this device is designed to assist those performing the classic plank exercise, where the body is prone, the hips are off the floor, and the forearms are stabilizing the upper body in a push up like position. With this device, an individual/patient places their torso on a platform to assist the plank maneuver. “Persons that are overweight, persons with impaired balance, and persons that, for whatever reason do not have four fully functioning limbs, often have considerable difficulty performing the exercise with the proper form, and for the necessary length of time to effectively train the targeted core muscle groups.” Those who benefit from this device have difficulty lifting the torso without assistance. While this device is portable, it is not designed for higher level lower back isometric strengthening by using the upper body weight (torso, head, arms) and additional lifting of a weight for exercise, since hands/upper extremities are not free. In addition, this apparatus is not designed to benefit the individual seeking a training gym strengthening program.

Another device is described in Monti, U S. Pat. Pub. No. 2019/0168062 A1 which states that it “is specifically designed for improved exercise through the variability of tension component for use in such exercises as plank exercise, situps, push-ups . . . ” The device enhances the classic exercise positions, including the plank exercise. Variable tension is applied to the torso while holding the plank position (push-up position on hands, forearms, elbows and toes.) The disadvantage of this device is that it is not designed to stabilize the pelvis and allow for a hands-free plank position isometric exercise that also includes lifting of weights. In addition, this device is bulky and heavy and not portable.

A foam roller is unstable and painful if used for isometric lower back strengthening. Typically, the roller is placed between a target muscle and the ground and is rolled back-and-forth, using body weight for massage. It is not designed for lower back exercises. The very nature of this device is to roll, while the body's weight overlies the device. As such, it is inherently unstable, and in the situation of performing a plank, especially the setting of facet arthritis, motion while performing the exercise could lead to serious injury, spasm and pain. In addition, if the roller shifts while performing the exercise it can cause compression of the genitalia causing discomfort. If it rolls under the abdomen it can lead to difficulty with respiration. Additionally, the contact point of the roller against the prone body is painful for lower back exercises due to its lack of viscoelastic cushion properties. For these reasons, the foam roller is not recommended for use for lower back extension exercises especially in the setting lower back pain, weakness and pathology.

An exercise ball also is not ideal for performing a plank back extension exercise. Like the foam roller, it is inherently unstable because it rolls. As such, when performing a plank, there is increased risk of injury while exercising, resulting in injury to the lower back, back spasm and pain. Additionally, lying prone over the exercise ball, creates contact/compression area from the genitalia to the abdomen, leading to discomfort and compromise to inspiration. Also, its bulky nature makes it difficult to perform exercises, especially those of the upper extremities, such as lifting weights. The exercise ball does not specifically contact the pelvis in a way that stabilizes it and allows an individual to maintain a static prone straight plank position while additionally allowing that individual to lift weights safely off the ground.

The half exercise ball (balance trainer) has the same contact point/area issue as the exercise ball. Lying prone over the exercise ball, creates contact/compression area from the genitalia to the abdomen, leading to discomfort and compromise to inspiration. Additionally, its bulky nature makes it difficult to perform exercises, especially those of the upper extremities, such as lifting weights. The half exercise ball does not specifically contact the pelvis in a way that stabilizes it and allows an individual to maintain a static prone straight plank position while additionally allowing that individual to lift weights safely off the ground.

The “classic” Roman chair is an apparatus with a metal platform/frame that connects a support for the thighs and a counter support to secure the ankles. The individual positions on the device, typically at 45-degree incline angle. A disadvantage of the Roman chair is that it is not portable because of its bulky heavy metal platform/frame. Another disadvantage is that while in the prone position, the thigh support does not stabilize the pelvis and thereby increases the risk of lower back injury and decreases its effectiveness. In addition, a person cannot maintain a static prone horizontal plank position while attempting to lift and release a weight since the Roman chair by design is not at ground level and not at 0 degrees (horizontal), thereby adding another element of risk.

Another such device similar in concept to the Roman chair is described in Cares, U.S. Pat. Pub. No. 2012/0122638 A1, which alleges an advantage in not requiring the user to partly dismount in order to reposition themselves to work one's obliques. “The user's torso hangs freely over the ground surface and the user bends about their waist for a desired number of repetitions.” This device is designed for dynamic strengthening of the core muscles (bending at the waist) not isometric strengthening thereby increasing the risk of injury. Further, like the Roman chair the user cannot maintain a static prone horizontal plank position while attempting to lift and release a weight since by design (to allow for bending at the waist), it is not a ground level, thereby also increasing the risk of injury. Also like the Roman chair this device is bulky and heavy and not portable. Lastly, this device is not designed to specifically stabilize the pelvis for prone plank exercises thereby increasing the risk of back injury and decreasing its effectiveness. Similarly, another device that incorporates the Roman chair concept and has the same disadvantages, is Romano et al., U.S. Pat. No. 11,904,198B1. It too is bulky and heavy, does not specifically stabilize the pelvis, and is not at ground level.

Another variation of the Roman chair is described in Robertson, U.S. Pat. No. 5,971,902A. Sold by Power Lift® as the “VARC”. This device allows for variable angles of the incline ranging from 75 degrees to horizontal 0 degrees. This device is expensive, bulky and heavy, it is not at ground level, does not stabilize the pelvis (Ref. 25), and cannot be positioned into the horizontal position without the assistance of another individual. Another device starts in the horizontal position, this device the “Glute Ham Developer” (GHD), is described in Henniger, U.S. Pat. No. 10,420,974B2. This device is bulky, heavy, not portable, and not at ground level. In addition, this device is designed to stabilize the body by creating a fulcrum at the thigh level. Its primary aim is to strengthen the gluteus muscles and the hamstrings. It is not designed to stabilize the pelvis and consequently it is not as effective for isolated lumbar extensor muscle strengthening. In addition, because the pelvis is not stabilized, there is increased risk of injury, pain and spasm, while performing isometric prone strengthening exercises secondary to increased risk of lumbosacral facet joint motion and instability. Another commercially available GHD device called “Compact GHD 2.0” sold by Strength Shop, while at ground level, is bulky, heavy, not portable, and has the same limitations and safety risks as U.S. Pat. No. 10,420,974B2, because it too is not specifically designed to stabilize the pelvis.

Another group of devices has the individual sitting in a machine, (ex. Medx lumbar extension machine, Converge Medical Technology) and performing isolated lumbar extension exercises (ILEX). Patents for these devices include U.S. Pat. or Pat. Pub. Nos.: U.S. Pat. Nos. 6,004,246A, 5,171,200A, 6,354,982, 4,462,252A, 5,928,112A, and US2016/0114207A1, U.S. Pat. No. 7,357,765B1. Chronic lower back pain including nonspecific mechanical lower back pain, has been successfully treated using this technique (Refs. 3 and 9) These machines have the advantage over the previously listed devices because they are designed to stabilize the pelvis which allows for more effective lumbar extension exercise by maximizing the resistive forces to the spine. Unfortunately, these devices are heavy, costly, and inconvenient. In addition, they are designed and used for dynamic lumbar extension exercises. Unlike an isometric device, these machines increase the risk of injury, pain and muscle spasm, since the lumbar facets are shifting while the resistive forces are applied during the dynamic lumbar extension exercise.

Another device that has been found to resolve lower back pain by strengthening the lower back extensor muscles is described in U.S. Pat. No. 12,285,612. Its efficacy is reported in a multicenter 5 year follow up FDA randomized control study in j.neurom.2024.01.006. Epub 2024 Mar. 12. This device is a surgically implanted electrical stimulator for strengthening the lower back extensor muscles, in particular, the multifidus. It strengthens the muscle by electrical activation twice per day. While it is proven effective, it is invasive, and costly.

SUMMARY

The disadvantages described are overcome by a novel device and method that allows individuals to perform high level core prone isometric strengthening exercises conveniently at home or in a gym or clinic setting. It is portable, lightweight, inexpensive, comfortable, noninvasive, and can be performed without the assistance of another individual.

In the prone position, a fulcrum is created by placing a specially designed bolster (Pelvic Fulcrum Support or PFS) at the symphysis pubis/pubic rami along the anterior pelvis. Anatomically, it is an ideal biomechanical location to create the fulcrum for enabling isometric prone strengthening exercises with the hands free. It is the only aspect/area of the skeleton anteriorly that articulates with the posterior spine, through the pelvic ring and sacrum. No previous device has taken advantage of this anatomic feature for creating a pelvic fulcrum, for the purpose of isolated isometric lumbar extensor muscle strengthening by creating a moment arm at the origin of the multifidus and erector spinae muscles. The pelvic fulcrum pivot point or area PFPA (located below the beltline and above the genitalia) connects the spine, torso, head and arms on one side, with the hips, thighs, legs, and feet balanced against on the other side. It is located in the front of the body parallel to the level of the tailbone (coccyx) posteriorly. With the PFS placed at the PFPA, the pelvic/spine articulation is loaded and stabilized, mitigating against facet motion, thereby decreasing risk of injury with resulting muscle spasm and pain in the lumbosacral spine while performing isometric prone strengthening exercises. Stabilization of the pelvis when performing isolated lumbar extension resistance training, has been found to be an important factor in achieving outcomes of decreased back pain and increased strength and endurance (Refs. 3 and 10). In addition, by EMG testing, the prone horizontal position (0 degrees spine extension) has been found to be the best position for activating and recruiting the important lumbar extensor muscles (i.e., multifidus and erector spinae muscles) (Refs. 10, 11, 12, 13, and 14) This is further supported by Ref. 15 using functional magnetic resonance imaging. The full weight of the body is concentrated on the small area of the PFPA, a bony prominence which is an inherently sensitive location. The PFS must be narrow, strong, stable and comfortable to create a pivot point for maintaining a seesaw-like effect, with the torso off the ground in the plank isometric position. Importantly, the apparatus enables the hands to be free for exercise, including lifting weights. Since the lumbar extensor muscles (in particular the multifidus) are stabilizing, postural, slow twitch, Type 1 muscle, whose operational length is virtually unchanged through trunk range of motion, prolonged tonic holding contraction exercise is essential (Refs. 14, 15, 16, 17, and 18). Static holding exercise has been found to create hypertrophy of the lumbar multifidus (transaxial CT scan images) whereas dynamic only exercises did not (Refs. 16 and 21). In addition, dynamic lumbosacral exercises, due to the movement of a loaded spine, carry a higher risk of injury compared to isometric exercises (Ref. 21). Comfort at the contact point of the body (PFPA) against the PFS is essential for successfully performing these prolonged endurance-strengthening exercises. The contact point of the PFPA mechanically creates a fulcrum through the pelvis that maximizes the torque on the back extensor muscles since their origin is at the sacrum and posterior pelvis. By performing isometric strengthening exercises in the prone horizontal position, the PFS apparatus and method safely maximizes one's ability to strengthen the lumbosacral core extensor muscles which increases spinal stability which in turn resolves persistent and recurring back pain.

One embodiment of the PFS includes a bolster with a viscoelastic cushion contacting the symphysis pubis pivot point or area PFPA supported by a hard foam/plastic lightweight housing. Another PFS embodiment has a suspension swing apparatus. The padded swing creates the fulcrum by suspending the body at the PFPA. Two pillars suspend the swing, supported and stabilized by a frame and cables. When the PFS swing is placed at the PFPA, the pelvic/spine articulation is stabilized, mitigating against facet motion, thereby decreasing risk of injury with resulting muscle spasm.

A bolster placed cephalad to the symphysis pubis (PFPA), (over the abdomen) makes inspiration difficult secondary to the contents of the abdominal cavity, pushing up and into the diaphragm. A bolster placed caudal to the symphysis pubis (PFPA) is painful secondary to impinging the genitalia. Further caudal, at the upper thigh level, the pelvis is no longer stabilized, increasing the risk of spinal injury and muscle spasm secondary to facet motion while performing strengthening exercises. In addition, this location loses the advantage of isolated lumbar extension exercise since it no longer stabilizes the pelvis. And in addition, losses its effectiveness since the larger gluteal and hamstring muscles substitute the forces generated by the lumbar extensor muscles (i.e., multifidus and erector spinae muscles) (Refs. 10, 23, 24, 25, and 26). With its narrow contact area at the pelvis symphysis pubis/pubic rami, the PFS allows the individual to hold the prone isometric position for periods of time, strengthening the lower back extensor stabilizing muscles. Various positions of the arms, coordinated with leg motions, increase strengthening. Strength training can be intensified in the following fashion. Before prone positioning, ankle weights (or a leg holder) are applied to the legs and the individual then positions over the PFS device. Once in the isometric prone position, a weight can then be lifted to the individual's chest, using the ankle weights or leg holder as a counter torque. In this way, the back and torso barely move while significantly increasing the load on the lumbar extensor muscles (i.e., multifidus and erector spinae muscles). This maneuver held for set periods of time, safely builds strength and endurance in these otherwise easily fatigued weak spinal stabilizing muscles. The force is released when the exercise is finished by simply dropping or placing down the held weight.

The PFS bolster and the PFS swing can be combined with an adjustable metal leg holder apparatus, which allows the individual to adjust the distance between the leg holder and PFS pivot point. The individual's body weight on the PFS bolster or swing further stabilizes the apparatus, making it a very secure construct for exercise.

While the PFS bolster and PFS swing are designed for core strengthening in the setting of pain and spine pathology, it does not preclude their use for safe efficient core strengthening and endurance training in the athlete. Further modification to the PFS can be made, designed specifically for training in the non-injured athlete. For example, a rounded base for PFS bolster adds instability to the construct, increasing engagement of the abdominal core muscles.

Another modification of the PFS bolster includes a curvilinear contoured surface for placement of the viscoelastic cushion to further accommodate for painful conditions in the area of the symphysis pubis. Alternatively, another embodiment has the PFS with a flat surface with two cushions attached to adjustable sliding platforms that can be positioned for the individual's preference.

In the clinical rehabilitation setting (i.e., post surgical or post injury) or the setting of an individual who is significantly weak, the PFS can be combined with a torso assistive lifting device to decrease the initial load on the lumbosacral spine. A physician/physical therapist directed rehabilitation program would be utilized, eventually progressing to a home program using the PFS with and/or without the assistive device.

Lastly, in the clinical rehabilitation setting, the PFS incorporates a force plate strain gauge load cell for measurement of work/effort expenditure. Output data is recorded and compared to previous work/effort data by the individual. Comparison to known value thresholds for resolution and prevention of back pain can be utilized. The individual can also use the instantaneous readout of their work/effort output to incentivize exercise.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the nature of the embodiments of the present disclosure may be had with reference the detailed description, taken in connection with the accompanying figures:

FIG. 1 is a diagram of the skeletal-body lying prone over the pelvic fulcrum support or “PFS” at the body's symphysis pubis/pubic rami pelvic fulcrum pivot point or area “PFPA”.

FIGS. 2A-2B & 3 are various diagrams depicting the PFS.

FIG. 4 is a cross-sectional view of the body shown in FIG. 1 where the body is lying prone over the PFS, representing the relationship of the PFPA with the spine.

FIGS. 5A-5C are alternative PFS embodiments where the PFS is a padded swing suspended by a metal frame and suspension wires.

FIG. 6 is a force diagram representation of FIG. 1.

FIG. 7 is a leg holder apparatus where the PFS is placed on a platform, combining to create an adjustable and stable construct for exercise.

FIG. 8 is a diagram demonstrating the method for identifying the symphysis pubis/pubic rami pelvic fulcrum pivot point or area “PFPA”.

FIG. 9 is a flowchart showing a PFS exercise method.

FIGS. 10A-10D depict an embodiment of the PFS which has a rounded frame with a flat surface supporting the cushion.

FIG. 11 is the PFS with a frame which has a curvilinear surface supporting the cushion.

FIGS. 12A-12B depicts an embodiment of the PFS with a frame that has two equal sized cushions attached to two adjustable sliding platforms.

FIGS. 13A-13B depict an embodiment of the PFS with adjustable legs.

FIG. 14 is the PFS with a cylindrical frame and a flat cushion.

FIG. 15 is the PFS combined with a torso assist positioner.

FIG. 16 shows the PFS with a force plate strain-gauge load cell and a wirelessly connected laptop computer used for output display, data storage, and analysis.

DETAILED DESCRIPTION

The present disclosure relates to an apparatus and method for performing comprehensive isometric back extensor core muscle exercises. The apparatus creates a fulcrum at the pelvic symphysis pubis level of the pelvis, allowing for hands-free exercises in the prone plank position. Details of the apparatus and method are elaborated upon more fully herein-after.

With reference, now to FIG. 1, an individual 10 places their prone body over the bolster PFS 12/13. A fulcrum is created at the pelvic symphysis pubis/pubic rami 11 along the anterior pelvis 14. The symphysis pubis/pubic rami 11, articulates with the posterior spine, through the pelvic ring and sacrum 14. Further shown in FIG. 4, where this cross-sectional view demonstrates where the pelvis makes contact and overlies the PFS 12/13. Here the pelvis 14 overlies the PFS 12/13 at the symphysis pubis/pubic rami 11 which articulates with the sacrum/spine 15. The symphysis pubis/pubic rami 11 creates an excellent pelvic pivot point/area PFPA 11, with the spine 15, torso 18, head 17, and arms on one side, counter-balanced by the hips, thighs, legs 16 and feet, on the other side (FIG. 1). Line 76 (FIG. 1), represents the pivot axis line going through the pelvis, traversing the coccyx bone “tailbone” 77, the PFPA 11 and supported by the fulcrum created by the PFS 12/13. With the pivot axis line 76 below or caudal to the origin of the lumbosacral extensor stabilizing muscles 85 (i.e. multifidus and erector spinae muscles), the PFS 12/13 creates the moment arm for loading and exercising of these muscles 85 with maximum torque.

For the first time user, the location of the PFPA 11 is not initially obvious. However, once having used the PFS 12/13, the individual becomes very facile at locating the PFPA 11 and properly positioning. There should be minimal to no discomfort if properly positioned. One can reliably locate the PFPA 11 by identifying the pivot axis line 76 in the following steps:

1. Along the back of the body, with one hand, first palpate the posterior spine 15 and locate the most inferior aspect of the spine (coccyx bone “tailbone” 77), at the superior aspect of the intergluteal cleft. (FIG. 8)

2. Once the coccyx bone 77 is identified, with the other hand, palpate the bony ridge of the PFPA 11 along the front of the body, directly anterior in a straight line from the coccyx bone 77 (FIG. 8). Plainly stated, the first hand is placed along the inferior spine, palpating the tailbone. The second hand is placed on the bony pelvic ridge anteriorly (PFPA 11), following an imaginary perpendicular line from the first hand. The person will then orient the PFS 12/13 beneath the PFPA 11 in accordance with FIG. 1.

FIG. 6 further depicts the body as a seesaw (with a theoretical plank 65) pivoting on the PFPA 11, overlying the fulcrum PFS 12/13, creating a moment arm of the total upper body weight 62, countered by the moment arm of the total lower body weight 63. The PFS 12/13 must be narrow, strong, stable and comfortable to create the pivot point for maintaining a seesaw-like effect, with the torso 18 off the ground in the plank isometric position. One embodiment of PFS 12/13 shown exemplary in FIGS. 2A-2B, 3, and 4, has a bolster comprising a hard foam/plastic beveled housing 13, supporting a domed durable medical grade viscoelastic polymer cushion 12 made of materials such as Akton® polymer (vulcanized cross-linked rubber), or for another example Aligel® (polyurethane gel). The viscoelastic polymer cushion 12, with its material properties that mimic fatty tissue, allow it to conform to the bony prominence and shape of the PFPA 11 and surrounding tissues and even when fully compressed, it continues to be soft and comfortable. These material properties mitigate against pain when the individual 10, positions their full weight 64 on the narrow PFS 12/13. There are other materials that can be utilized for cushion 12 (i.e. foam, foam on gel and gel foam for example), they tend to be more painful because when fully compressed by the weight 64 they become hard. Another less expensive but viable embodiment for cushion 12 is a TPU thermoplastic polyurethane air bladder cushion with open cell foam within it. The air pressure within the bladder can be adjusted, thereby changing the elasticity of the cushion 12. The individual 10, fine tunes the elasticity by increasing or decreasing the amount of air pressure within the bladder. The heavier the weight 64 on cushion 12, the higher the air pressure needed to maintain sufficient stiffness. If the air bladder loses air pressure over time, or if different individuals use the device, the air bladder would need to be recalibrated. While the air bladder cushion 12 may not have the durability or comfort as one of the viscoelastic polymer cushions it is a viable option. In general, the cushion 12 measures 4.5 inches wide by 12.5 inches long and 3 inches height, while the housing PFS 13 has a base of 10 inches by 12 inches and height of 9 inches with a flat platform width of 4 inches. Other modifications, combinations, sizes, and shapes of base 13 and the cushion 12 are suitable as well. As an example, another embodiment of the device features a curvilinear surface of PFS 13 (FIG. 11). This modification more closely matches the contour of the anterior pelvis PFPA 11. The cushion 12 overlies the smooth indentation in the PFS 13 for placement of the PFPA 11. This feature further distributes forces and mitigates against pain. The deeper the indentation, the more the forces shift laterally away from the symphysis pubis (which may be painful secondary to previous trauma or previous incision scars such as from a C-section, or sensitive genitalia) and more toward the pubic rami and hips. Alternatively, in another embodiment, cushion 12 is split into two equal parts which are attached to two adjustable sliding locking platforms 78 (Dryline carriage plates) that slide on an aluminum rail tack 79 (Dyline® double rail) overlying and attached to the superior flat surface of PFS 13. The cushions 12 on the track 79 can be adjusted by the user for their personal preference and locked into position using the locking bolts 80 (FIGS. 12A-12B). Another embodiment (FIGS. 13A-13B) has adjustable legs 81 at the base of PFS 13. The adjustable legs 81 allow the platform to be raised or lowered accommodating different body habituses such as larger and/or overweight individuals. In this embodiment the adjustable legs 81, are POWERTEC corner leveling feet, attached to the corners at the base of PFS 13.

The efficiency of the plank exercise is significantly increased by the invention by safely intensifying the exercise, for example, in the following fashion. Before prone positioning, ankle weights (or a leg holder (such as Squatz™ sit up machine)) 61 may be optionally applied to the legs and the individual then positions over the PFS device 12/13 at the PFPA 11. Once in the isometric prone position, the hands-free feature allows one or more weights 60 to be lifted to the individual's 10 chest 18, using the ankle weights/leg holder 61 as a counter torque FIG. 6. In this way, the spine 15 and torso 18 barely move while the forces are increased significantly on the core lumbar extensor muscles and can be held for a period of time, thereby enhancing the results and effects of the exercise. The force is easily released when the exercise is finished by simply dropping or placing down the held weight(s) 60.

The force diagram FIG. 6 is a mechanical representation of the body and the PFS. FIG. 6, depicts the body as a seesaw, (with a theoretical plank 65) pivoting at the PFPA 11, overlying the fulcrum PFS 12/13, creating a moment arm 62 by the handheld weights 60 and upper body weight, countered by the moment arm 63 of leg weights 61 and lower body weight. As the forces of the handheld weights 60 and leg weights 61 increase the reactionary force 64 at the fulcrum PFPA 11 increases, loading and stabilizing the pelvis 14/sacrum spine 15 articulation, mitigating against facet motion thereby decreasing risk of injury with resulting muscle spasm. Once properly positioned over the PFPA 11 the user can feel the pelvis 14/sacrum 15 stabilize. The PFS 12/13 by design, helps the user locate and position over the PFPA 11, thereby maximizing the effect of the exercises while minimizing the risk of injury and pain. In this simple but novel way, the PFS 12/13, effectively creates a pelvic stabilizing feature similar to the bulky, much more expensive, inconvenient lumbar extension machines (ex. Medx Lumbar Extension Machine), which stabilizes the pelvis in the sitting position with multiple restraints for isolated lumbar extension exercises (ILEX). In addition, the isometric position of 0 degrees lumbar extension utilized by the PFS 12/13 has been shown using EMG testing (Refs. 11 and 12) to be the best biomechanical position for activation and recruitment of the targeted lumbar extensor muscles 85 (i.e., multifidus and erector spinae muscles).

FIGS. 5A-5C depict embodiments of a suspension apparatus 50 “pelvic swing” with two metal pillars 51, attached to a metal frame 52. The pillars are stabilized by a crossbar 53. A platform 54 is suspended by adjustable suspension wires 55 with locking winches 56, Figure Sa. The cushion 12 is attached to the platform 54 creating the fulcrum for the pelvic PFPA 11, FIG. 5b. The nature of the suspension apparatus 50 allows the platform 54 to have various shapes and configurations, including a cylindrical option, which allows the cushion 12 to be rounded creating a viscoelastic “roller” FIG. 5c. The “pelvic swing” may be more suited for the therapy/clinical environment, where the physical therapist can customize the device for various body habituses and needs. While still portable the PFS “pelvic swing” 50 is heavier and more robust than the first embodiment where the platform 13 is a foam/plastic housing. The cushion 12 in the PFS “pelvic swing” 50 may be any of the materials described above with respect to the embodiments depicted in FIGS. 1-4 (e.g., the cushion 12 may be (or include) a viscoelastic polymer such as vulcanized cross-linked rubber or polyurethane gel, or the cushion 12 may be (or include) an air bladder, such as a thermoplastic polyurethane air bladder with open cell foam in the air bladder).

FIG. 7 depicts a more robust secure leg holder. As mentioned previously a portable leg holder such as the Squatz™ sit up machine can be utilized instead of ankle weights. This device has suction cups that secures it to a smooth clean floor surface. Unfortunately, the suction cups do not reliably adhere to the floor and can come free during exercise thereby increasing the risk of injury. This risk is overcome by utilizing the leg holder apparatus 66. The PFS bolster 12/13 or swing 50 can be placed/attached to an adjustable metal leg holder apparatus 66 on the platform 72. With the apparatus support 73 on rollers, the leg holder 67 on track 68 can be easily lengthened and shortened into the housing of the spring-loaded locking mechanism 70, which is attached to the frame 74 of platform 72. The height of the crossbar 69 of the leg holder 67 is adjustable by a spring-loaded locking mechanism 71 as well. The individual's 10 body weight on the PFSs 12/13 or 50 on platform 72 further secures the apparatus 66 creating a stable construct for exercise.

Embodiments of the present disclosure allow for back core strengthening in the setting of lumbar sacral spine pathology and pain (e.g. facet arthritis, degenerative disc disease, nonspecific mechanical low back pain etc.). However, it does not preclude its use for safe, efficient core strengthening and endurance training in the athlete (e.g. gymnasts, swimming, weightlifting, golf, football, etc.). Anyone who would benefit from a strong stable core with strong extensor lumbar extensor muscles will benefit from the embodiments of the present disclosure. In the setting specifically of the non-injured athlete, enhancements in the PFS design can further optimize its application. Modified shape of the PFS 13 featuring a rounded base 75 with a flat surface 82 underlying the domed cushion 12 (FIGS. 10A-10D), introduces an element of instability that increases difficulty and promotes greater gains in core strength, balance, and endurance. In particular, in this embodiment the abdominal muscles (flexors) are further engaged to stop the tendency of the device to roll, while simultaneously utilizing the lumbar extensor muscles to maintain the isometric plank position. Another embodiment with the same concept, is FIG. 14, where the base PFS 13 is now a completely rounded/cylindrical 83, underlying 84 which is a flat cushion 12. Rounded versions of the PFS base, FIGS. 14, 10A-10D, and 5C, allow the user to more easily shift their body while lying prone on the PFS. These devices act as rollers and allow the contact point against the body to move towards the toes or towards the head by simply shifting the body and rolling the PFS. While these designs are more unstable, the individual knows when they are comfortably positioned at the PFPA 11, when there is minimal to no discomfort, the pelvis is locked and stabilized, and the body mechanics feel natural.

In the clinical rehabilitation setting (i.e. post-surgical, post injury, reflex inhibition (Ref. 26)) or the setting of a deconditioned individual who is significantly weak and lacks endurance, the PFS can be combined with a torso assistive lifting device to decrease the initial load on the lumbosacral spine. (FIG. 15) This combination allows for gentle progressive stimulation, strengthening, and proprioception retraining of the lumbosacral extensor stabilizing muscles. A medical grade high-density polyfoam torso assist positioner 86, such as the Alimed® vinyl-covered deluxe knee bolster/lumbar positioner can be pre-positioned to support the individual's torso in the prone position. A physical therapist can direct/assist the individual in positioning over the PFS 12/13 and adjust the torso assist positioner to support the individual's torso. The torso weight compresses the polyfoam within the positioner that creates an indentation with a corresponding deflection force that assists the individual while performing the isometric plank exercise. Adjustments can be made to the contact point against the torso and the height of the positioner by placing or removing foam rectangular flat support cushions 87 under the positioner. The individual can progress to a home program using the PFS 12/13 with or without the assistive device.

In the clinical rehabilitation setting, the PFS is enhanced by measuring the forces that are applied to it, as well as the amount of time that those forces are applied. The combination of lumbar muscle strength and endurance is extremely important in the rehabilitation and prevention of lower back pain. (Refs. 7 and 8) Surface electromyography (sEMG) has been shown to reliably assess multifidus muscle function (Ref. 14), while having a linear relationship with isometric tension. (Ref. 27) The plank position (horizontal (0°) parallel to the floor) provides the highest torque on the lumbar spine and resulted in the highest EMG activity of the lumbar paraspinal musculature. (Refs. 5 and 11) The moment arm torque can be further increased by placing the hands and arms away from the axis of rotation (example by placing hands behind the head), which in turn further increases EMG activity. (Ref. 13) The force measured on the PFS while changing positions of the hands such as outstretched over the head or behind the head, has been found to significantly increase without increasing the weight of the torso. Further increases in force on the PFS and sEMG output occur by lifting weights, which is increased further still by changes in hand position. The last 30 years of literature regarding strengthening of the lumbar spine have been focused primarily on dynamic exercise, reporting maximal voluntary contraction force sEMG readings. The variable of time which reflects endurance has been overlooked. (Ref. 29) The PFS apparatus and method is designed for isometric strengthening and endurance by holding various plank positions for various periods of time. The measurement of this activity is very important. Isometric exercise has no change in length or angle, and therefore work (force×distance) cannot be calculated. The concept of force time integral J=∫F(t)dt, where: J=impulse, F=time dependent force 64 Figure (Ref. 16), is utilized to reflect the work/effort expenditure of the lumbar isometric extension exercise. This principal has been successfully applied in other medical applications such as orthopedics (i.e. gait analysis) and cardiology for cardiac ablation. (Refs. 30 and 31)

FIG. 16 depicts the PFS 12/13 with a force plate strain gauge load cell 88, mounted between the cushion 12, and the base 13. The force plate load cell 88 is a transducer configured to convert mechanical force input into an electrical output signal. In one or more embodiments, the load cell 88 may include a plurality of strain gauges arranged in a Wheatstone bridge configuration and the plurality of strain gauges may be mounted on a flexure element. An example of the force plate 88 is the Kinvent K-force Plate™. This device, utilized for gait analysis, has the capability of calculating the force time integral J=∫F(t)dt, where F is the force 64 on the PFS 12/13 measured by the force plate load cell 88. Data is collected and stored by a wireless connection (e.g., Bluetooth) to a data acquisition and display device or system 89 (e.g., a portable electronic device, such as a laptop computer, a smartphone, or a tablet computer) and can be seen in real-time (or substantially in real time) by the individual 17 using the PFS. The force plate load cell 88 can also be mounted in other locations such as under the base 13, or under the platform of the pelvic swing 50, or on the surface of the platform 72.

In one or more embodiments, the data acquisition and display device 89 includes a processor, a non-transitory memory device connected to the processor, a wireless network adapter, and a power supply (e.g., a secondary battery). Wireless links between the force plate load cell 88 and the data acquisition and display device 89 may include Bluetooth™, Bluetooth Low Energy or other protocols with suitable authentication and encryption to protect patient data. The memory device includes computer-readable instructions (executable code) which, when executed by the processor, cause the data acquisition and display device to receive, via the wireless network adapter, the electrical output signal from the force plate load cell 88 that is indicative of the force from the user on the PFS 12/13, calculate the force time integral J=∫F(t)dt based on the electrical output signal and the duration that the user utilized the PFS 12/13, and to display the force time integral on the display of the data acquisition and display device 89. The area under the force time curve (determined by calculating the integral J=∫F(t)dt) is a work/effort output value. In one or more embodiments, the instructions, when executed by the processor, may further cause the data acquisition and display device 89 to store the force measurement and/or the force time integral in the non-volatile memory. Additionally, in one or more embodiments, the instructions stored in the memory device, when executed by the processor, may cause the data acquisition and display device 89 to compare the measured force and/or the calculated force time integral to a threshold value (e.g., known reference value(s) for which back pain prevention has been obtained) and/or to compare the measured force and/or the calculated force time integral to historical data of the same user (e.g., a baseline or other previous values obtained from the patient). In one or more embodiments, the instructions stored in the memory device, when executed by the processor, may cause the data acquisition and display device 89 to display an alert on the display based on the results of this comparison (e.g., an alert indicating that the calculated force time integral is above or below a threshold or baseline value). As used herein, the term “processor” includes any combination of hardware, firmware, memory and software, employed to process data or digital signals. The hardware of a controller may include, for example, a microcontroller, application specific integrated circuits (ASICs), general purpose or special purpose central processors (CPUs), digital signal processors (DSPs), graphics processors (GPUs), and programmable logic devices such as field programmable gate arrays (FPGAs). In a processor, as utilized herein, each function is performed either by hardware configured, i.e., hard-wired, to perform that function, or by more general purpose hardware, such as a CPU, configured to execute instructions stored in a non-transitory storage medium or memory. A processor may contain two or more processors, for example, a processor may include two processors, an FPGA and a CPU, interconnected on a PCB. The non-volatile memory device may be any suitable type or kind of memory, such non-volatile read/write memory (e.g., flash memory, hard disk drives (HDD), or solid-state drives (SDD)), non-volatile read-only memory (ROM) (e.g., programmable read-only memory (PROM) or erasable programmable read-only memory (EPROM)), or a combination thereof.

The force F 64 can be increased by increasing the torque on the lumbar spine by holding weights 60 or changing positions of the arms (for example outstretched or overhead while using the Pelvic Fulcrum Support). An equivalent work/effort output could be obtained with a less strenuous exercise with lower force F 64 but held for a longer period of time. In this way, the individual builds endurance while also building strength. In the setting of an individual 17 who is rehabilitating their lower back from injury or surgery, by performing several less intense exercises with rest between exercises (and using a torso assist positioner support 86/87), the cumulative work/effort output is a very helpful piece of information for the medical team to gauge progress and design protocols. In addition, the individual 17 using the device PFS 12/88/13 can be incentivized by seeing instantaneous work/effort output on a computer screen 89.

FIG. 9 is a flowchart depicting the method and steps an individual follows to use the PFS. As shown in FIG. 9, the method of performing a hands-free plank core exercise with the PFS 12/13 or the pelvic swing 50 includes: (i) a task of palpating the user's tailbone 77 and then the bony ridge of the user's PFPA 11; (ii) a task of the user positioning prone over the PFS 12/13 or the pelvic swing 50 and activating the force plate load cell 88 and the data acquisition system 89; and (iii) a task of the user placing the user's full body weight 64, at the user's PFPA 11, on the cushion 12 of the PFS 12/13 or the pelvic swing 50. In one or more embodiments, the method may include utilizing a leg support, which may include a task of applying leg weights to the user's ankles 61 or a task of placing the user's ankles/legs under the crossbar 69 of the leg holder 66. Additionally, in one or more embodiments, the method may include (a) a task of utilizing the torso assist positioner 86 to hold the plank position for a period of time while measuring the force output with the force plate load cell 88, calculating the force time integral based on the measured force output during the time in which the user held the plank position, and displaying the force time integral on a display of the data acquisition system 89, (b) a task of stopping the exercise by placing the user's hands on the ground, and (c) a task of using the user's hands and toes to lift off of the PFS 12/13 or the pelvic swing 50. In one or more embodiments in which the torso assist positioner 86 is not utilized, the method may include (1) a task of performing the exercise by lifting the user's hands off of the ground, (2) a task of lifting a weight 60 to the user's chest 18, (3) a task of holding the plank position for a period of time while measuring the force output with the force plate load cell 88, calculating the force time integral based on the measured force output during the time in which the user held the plank position, and displaying the force time integral on a display of the data acquisition system 89, (4) a task of stopping the exercise by placing the user's hands on the ground, and (5) a task of using the user's hands and toes to lift off of the PFS 12/13 or the pelvic swing 50.

A person of ordinary skill in the art will recognize that various alternative embodiments of the PFS having different shapes, sizes, cushions, swings/slings and/or materials may be utilized to enable a pelvic support to create a fulcrum at the user's symphysis pubis/pubic rami for enabling the user to perform back and core exercises. The invention shall not be limited by the embodiments, rather the scope of the invention is set forth in the claims below.

REFERENCE LIST

• [1] Panjabi M A, Abumi K U, Duranceau J O, Oxland T. Spinal stability and intersegmental muscle forces: a biomechanical model. Spine. 1989 Feb. 1; 14(2):194-200.
• [2] Panjabi M M. The stabilizing system of the spine. Part I. Function, dysfunction, adaptation, and enhancement. Journal of spinal disorders. 1992 Dec. 1; 5:383.
• [3] Steele J, Bruce-Low S, Smith D. A review of the clinical value of isolated lumbar extension resistance training for chronic low back pain. PM&R. 2015 Feb. 1; 7(2):169-87. doi: 10.1016/j.pmrj.2014.10.009
• [4] Goel V K, Kong W, Han J S, Weinstein J N, Gilbertson L G. A combined finite element and optimization investigation of lumbar spine mechanics with and without muscles. Spine. 1993 Mar. 30; 18(11): 1531-1541.
• [5] Mayer J, Mooney V, Dagenais S. Evidence-informed management of chronic low back pain with lumbar extensor strengthening exercises. The spine journal. 2008 Jan. 1; 8(1):96-113. doi: 10.1016/j.spine.2007.09.008
• [6] Smrcina Z, Woelfel S, Burcal C. A systematic review of the effectiveness of core stability exercises in patients with non-specific low back pain. International journal of sports physical therapy. 2022 Aug. 1; 17(5):766.
• [7] Biering-Sorensen F. Physical measurements as a risk indicators for low-back trouble over a one-year period. Spine. 1984 Mar. 1; 9(2):106-119
• [8] Luoto S, Heliovaara M, Hurri H, Alaranta H. Static back endurance and the risk of low back pain. Clinical Biomechanics. 1995 Sep. 1; 10(6):323-324
• [9] Trybulski R, Michal W, Malgorzata S, Bogdanski B, Bichowska-Paweska M, Ryszkiel I, Gepfert M, Clemente F M. Impact of isolated lumbar extension strength training on reducing nonspecific low back pain, disability, and improving function: A systemic review and meta-analysis. Nature.com/scientificreports. 2025; 15(6426):1-15
• [10] Smith D, Bissell G, Bruce-Low S, Wakefield C. The effect of lumbar extension training with and without pelvic stabilization on lumbar strength and low back pain. Journal of back and musculoskeletal rehabilitation. 2011 November; 24(4):241-9. doi: 10.3233/BMR-2011-0301
• [11] Mayer J M, Verna J L, Manini T M, Mooney V, Graves J E. Electromyographic activity of the trunk extensor muscles: Effect of varying hip position and lumbar posture during Roman chair exercise. Archives of physical medicine and rehabilitation. 2002 Nov. 1; 83(11):1543-6.
• [12] Mayer, J. M., Udermann, B. E., & Verna, J. L. (2022). Electromyographic analysis of the lumbar extensor muscles during dynamic Exercise on a Home Exercise Device. Journal of Functional Morphology and Kinesiology, 7(1), 26. doi: 10.3390/jfmk7010026
• [13] Mayer J M, Graves J E, Robertson V L, Pierra E A, Verna J L, Ploutz-Snyder L L. Electromyographic activity of the lumbar extensor muscles: effect of angle and hand position during Roman chair exercise. Archives of physical medicine and rehabilitation. 1999 Jul. 1; 80(7):751-5.
• [14] Arokoski J P, Kankaanpss M, Valta T, Juvonen I, Partanen J, Taimela S, Lindgren K A, Airaksinen O. Back and hip extensor muscle function during therapeutic exercises. Archives of physical medicine and rehabilitation. 1999 Jul. 1; 80(7):842-50.
• [15] Flicker P L, Fleckenstein J L, Ferry K, Payne J, Ward C, Mayer T, Parkey R W, Peshock R M. lumbar muscle usage and chronic low back pain magnetic resonance image evaluation. 1993 Apr. 1; 18(5) 582-6.
• [16] Danneels L A, Vanderstraeten G G, Cambier D C, Witvrouw E E, Bourgois J D, Dankaerts W, De Cuyper H J. Effects of three different training modalities on the cross sectional area of the lumbar multifidus muscle in patients with chronic low back pain. British journal of sports medicine. 2001 Jun. 1; 35(3):186-91.
• [17] McGILL SM. Kinetic potential of the lumbar trunk musculature about three orthogonal orthopaedic axes in extreme postures. Spine. 1991 Jul. 1; 16(7):809-15.
• [18] Richardson C A, Jull G A. Muscle control-pain control. What exercises would you prescribe. Man ther. 1995 Nov. 1; 1(1):2-10.
• [19] Kim C, Gottschalk L, Eng C, Ward S, Lieber R. 160. The multifidus muscle is the strongest stabilizer of the lumbar spine. The Spine Journal. 2007 Sep. 1; 7(5):76S.
• [20] Ward S R, Kim C W, Eng C M, Gottschalk IV LJ, Tomiya A, Garfin S R, Lieber R L. Architectural analysis and intraoperative measurements demonstrate the unique design of the multifidus muscle for lumbar spine stability. JBJS. 2009 Jan. 1; 91(1):176-85. doi: 10.2106/JBJS.G.01311
• [21] Jensen B R, Jorgensen K, Hargens A R, Nielsen P K, Nicolaisen. Physiological response to submaximal isometric contractions of the paravertebral muscles. Spine. 1999 Nov. 15; 24 (22):2332-2339.
• [22] Ng J, Richardson C. EMG study of erector spinae and multifidus in two isometric back extension exercises. Australian Journal of Physiotherapy. 1994 Jan. 1; 40(2):115-21.
• [23] Graves J E, Webb D C, Pollock M L, Matkozich J, Leggett S H, Carpenter D M, Foster D N, Cirulli J. Pelvic stabilization during resistance training: its effect on the development of lumbar extension strength. Archives of physical medicine and rehabilitation. 1994 Feb. 1; 75(2):210-5.
• [24] Udermann B E, Graves J E, Donelson R G, Ploutz-Snyder L, Boucher J P, Iriso J H. Pelvic restraint effect on lumbar gluteal and hamstring muscle electromyographic activation. Archives of physical medicine and rehabilitation. 1999 Apr. 1; 80(4):428-31.
• [25] Verna J L, Mayer J M, Mooney V, Pierra E A, Robertson V L, Graves J E. Back extension endurance and strength: the effect of variable-angle roman chair exercise training. Spine. 2002 Aug. 15; 27(16):1772-7.
• [26] Mayer J M, Udermann B E, Graves J E, Ploutz-Snyder L L. Effect of Roman chair exercise training on the development of lumbar extension strength. The Journal of Strength & Conditioning Research. 2003 May 1; 17(2):356-61.
• [27] Hides J A, Richardson C A, Jull G A. Multifidus muscle recovery is not automatic after resolution of acute, first-episode low back pain. Spine. 1996 Dec. 1; 21(23):2763-9.
• [28] Moritani T, DeVries H A. Reexamination of the relationship between the surface integrated electromyogram (IEMG) and force of isometric contraction. American Journal of Physical Medicine & Rehabilitation. 1978 Dec. 1; 57(6):263-277.
• [29] Udermann, B. E., Mayer J. M., Graves J. E., Murray S. R. Quantitative assessment of lumbar paraspinal muscle endurance. J. of Athletic Training. 2003, 38(3): 259-262.
• [30] Deffeyes, J. E., & Peters, D. M. Time-integrated propulsive and braking impulses do not depend on walking speed. 2021 Gait & Posture, 88, 258-263. https://doi.org/10.1016/j.gaitpost.2021.06.012
• [31] Jean-Benoit le Polain de Waroux 1, Rukshen Weerasooriya 2, Kalilur Anvardeen, etal. Low contact force and force-time integral predict early recovery and dormant conduction revealed by adenosine after pulmonary vein isolation. Europace. 2015 June; 17(6):877-83.