The Cage:
Maximizing Potential for Hypertrophy
Final Report
St. Francis Xavier University: Department of Engineering
ENGR 232:00 – Design and Communication II
Dr. Oguejiofor
James Gough / ID: 201101806Cole Ferguson / ID: 201103843
Andrew Wilson / ID: 201006795
Cyrus MacLellan / ID: 201006369
April 12, 2013
1i
Abstract
Methods for training the bicep muscles often lack the ability to allow an individual to put the most effort into lifting a weight while maintaining proper form. The Cage corrects the lifting technique and decreases the risk of injury by allowing for the controlled motion of the upper arm during a bicep curl. The machine is also a multipurpose piece of gym equipment suitable for a number of exercises in addition to the bicep curl. Its purpose is to help people increase the effectiveness of their workout at the gym in order to realize their fitness goals.
1i
Table of Contents
Abstract
Table of Contents
List of Figures
Introduction
Project Overview
Muscle Growth
Hypertrophy
Advantages
Frame Design
Armrest Design
Pulley System
Design Setbacks
Cost Breakdown
Conclusion
Appendices
Survey
Scheduling
Calculations
CAD
Prototype photos
Demonstration of Exercises
References
List of Figures
FIGURE 1.1, Steelmac Limited Antigonish
FIGURE 1.2, Kent Dartmouth
FIGURE 1.3, Rona Elmsdale
FIGURE 1.4, Princess Auto Dartmouth
FIGURE 1.5, Central Antigonish
FIGURE 1.6, Highland Building Supplies Antigonish
FIGURE 1.7, Metals ‘R’ Us Dartmouth
FIGURE 1.8, Canadian Tire
FIGURE 2.1
FIGURE 2.2
FIGURE 2.3
FIGURE 3.1 February Schedule
FIGURE 3.2 March Schedule
FIGURE 3.3 April Schedule
Figure 4.1, Force analysis of the frame and armrest support
Figure 4.2, Force analysis of the bicep using free weights and cables
Figure 4.3, Shear and bending diagrams of the frame pillars.
Figure 4.4, Maximum allowable shear calculation for a beam in the frame
Figure 4.5, Analysis of proposed pulley system
Figure 4.6, Force analysis of the pin holding the pulley in place.
Figure 5.1, Frame details
Figure 5.2, Armrest detail
Figure 5.3, Pulley to frame support detail
Figure 5.4, Wiper details
Figure 6.1, The Cage frame without armrests, pulleys, or weight-mounts
Figure 6.2, the armrest
Figure 6.3, view of the armrest from where you would stand during exercise
Figure 6.4, the underside of the armrest, showing a clearer view of where the armrest is welded to the collar.
Figure 6.5, close up view of the pulley mounted to the armrest.
Figure 6.6, close up of the sliding collar attached to the armrest
Figure 6.7, the pulley/wiper system attached to the frame.
Figure 6.8, Close up view of the wiper
Figure 6.9, side view of the wiper
Figure 6.10, Weight stack collars
Figure 6.11, Bracing of the pockets that contain the square tubing that supports the sliding collars.
Figure 6.12, Miscommunication leading to the top of the frame becoming the bottom of the frame.
Figure 7.1, James demonstrating the bicep curl.
Figure 7.2, James demonstrating various other exercises on the Cage. From top left, in clockwise order, they are: chest press, dips, tricep pulldowns, pull-ups, and standing rows.
1i
1
Introduction
The Cagewas designed to perfect the bicepcurl exercisethereby inducing maximum hypertrophy in the bicep muscles. Hypertrophy is the action by which muscles repair themselves and grow after strenuous activity. The Cageis an improvement over traditional bicep exercising techniques because it allows for the full range of motion of the bicep muscles,while keeping the biceps in constant tension.Improper form is often shown by both new and experienced gym-users. Ensuring gym-usersdemonstrate of proper form is essential to avoid injury, maximize muscle growth and increase muscle strength. The effectiveness of cable-weight machines lies in their ability to help correct improper form for both inexperienced and seasoned individuals. Furthermore, cable-weighted machines have additional safety features engineered into their designs that render them safer than free weights.
Project Overview
The final report will provide details on the concepts of bodybuilding and weight training as well as explain the design process that led to the construction of the final prototype.
Muscle Growth
When an individual lifts weights his or her goal is to overload the muscles to purposely damage the structure of the muscle. Muscles are made up of muscle fibers; these are the cells that make up muscle tissue and are limited to a set number of fibers in each muscle. These fibers are made from various layers of amino acids (a form of protein). Muscle contraction is caused by calcium, which allows the myosin (another form of protein) to attach to the actin (a third form of protein). This generates tension in the muscle fibers. Although the termcontractionimplies shortening, when referring to the muscular system, it means muscle fibers generating tension. Overloading the muscle can cause the muscle fiber to tear slightly, which is called a micro tear.In response to the micro tears, the body will use satellite cells (cells that have the potential to become new muscle fibers) to fix the tears building them up thicker each time to prevent against future damage.Pain arises while lifting weights as a result of the damage caused to the muscle fibers. This pain feels like a burning sensation that feels very different from pain experienced when one breaks a bone.
Even though the main idea behind lifting weights is to purposely damage the body, the end result is actually beneficial to the muscles. Indeed, the human body was made to adapt to its environment in order to survive. When muscles are overloaded they become fatigued and damaged. The body produces an inflammatory response to adapt to the overload and damage to muscles. Blood and water rushes to the site of damage to provide nutrients, notably calcium. These nutrients make their way into damaged cells where biochemical reactions take place to produce proteins, which are used to repair and grow muscles. This inflammatory response repairs the muscles bigger and stronger than they were previously.(LeMouse,2006).
Hypertrophy
There are two types of muscle growth: hypertrophy and hyperplasia. Hypertrophy is the increase in muscle size due to an increase in the size of muscle fibres. As explained in the project proposal, there are two types of hypertrophy: short-term and chronic. Short term occurs during a workout and for a few hours after a workout, while chronic hypertrophy typically will last a few days after a workout. In addition to these two types of hypertrophy, hypertrophy can further classified as sarcomere or sarcoplasmic. Sarcomere means having a smaller increase in muscle diameter as a result of exercise but a greater increase in muscle density due to water retention. Sarcoplasmic results from exercise and is manifested as a greater increase in muscle diameter but a decrease in muscle density. Hyperplasia is the increase in muscle size due to an increased number of muscle fibres, which is a result of mitosis or cell division among older skeletal muscle cells (LeMouse, 2006).
Advantages
Proper form of the traditional bicep curl is demonstrated by positioning the shoulders back and down while keeping the elbows laterally stationary resulting in a controlled motion restricted to the biceps only. The Cage ensures proper positioning of the upper arms by raising and supporting them in a comfortable position parallel to the ground (see figure 7.1). In this position, the upper arm has a reduced moment about the shoulder. The reduced moment about the shoulder minimizes the body’s ability to engage the shoulder, back and tricep muscles and requires the arm to engage only the bicep muscles (figure 4.2). Meanwhile, the design of the arm support inhibits unwanted lateral translation of the elbow (figure 5.2).
The cable allows the bicep muscle to be exercised during the full range of motion whereas free weights are limited in their effectiveness due to a reduced range of effective motion. The effective range of motion in a free weight bicep exercise runs from the weight being held at the user’s side to the point at which the center of gravity of the weight exceeds 90 degrees above the horizontal. The Cage was designed to allow the bicep to consistently oppose the tension in the cable throughout the entire range of motion.
Frame Design
The frame (figure 5.1, 6.1) was designed believing that it is possible to have other exercise equipment attached to the frame to create a multi-purpose piece of gym equipment. As a result, the frame had to incorporate a very sturdy design (figure 4.1, 4.3, 4.4) and is comparable in size with other common pieces of gym equipment. When comparablewith other pieces of gym equipment such as the smith machine(L x W x H), 49” x 87” x 93”, and lat pull-down machine54" x 33" x 89", which are two essential pieces of gym equipment, the Cage (48" x 48" x 84") is smaller in size. The top and bottom structures are made of 2”x2”x3/16” angle iron cut on 45 degree angles to 48” lengths. The design was to have the top portion be made of four segments welded into a square. The bottom was to be welded utilizing three segments welded square with an additional piece added at the midpoint, connecting the two side pieces to increase rigidity. By using only three members this would eliminate a tripping hazard when entering and exiting the machine. On the top and bottom pieces, four pockets (figure 6.11) made of 2 ½” x 2 ½” x 0.188” square tubing were welded onto 4 ½”x 6” x 3/16” plates welded 21” on center at the front of the structure. Additionally, pockets of the same material were welded at the midpoints on either side of the structure. These pockets support four posts made of 2” x 2” x 0.125” square tubing. The four vertical posts reside inside the pockets at the top and the bottom to allow for easy assembly. Along either of the two side posts, collars (figure 6.6) made of 2 ½” x 2 ½” x 0.188” square tubing 12” long with a ½” hole centered at 6” through the collar slide along the posts.Pins that pass through ½” holes drilled through the vertical posts spaced 1” apart support the collars. The square posts on the front of the frame guide the weigh stacks (figure 6.10) made of 2 ½” x 2 ½” x 0.188” square tubing 24” long. 2” diameter circular tubing was welded to the center of the weight stacks to allow the user to load weights onto the machine. A 4” long piece of flat bar was welded to the top of the weight stack with a ½” hole drilled to allow a cable with a breaking strength of 1800 lbs to be attached to the weight stack. The cable runs through the pulley system (figure 6.7) and attaches to handles.In addition to the vertical square tubing, 2”x2”x3/16” angle iron was cut to 84” lengths and is bolted using 3/8” x 1” bolts to the top and bottom structures. 12 2” x 24” x 3/16” flat bar members are added for additional rigidity. Brackets are designed to house the pulleys on the front post pockets made out of flat bar (figure 6.8, 6.9). The frame is designed to allow the structure to be easily assembled and disassembled in a short period of time using only hand tools.
Armrest Design
The frame was designed and built independent from the armrest. The armrest(figure 6.2) is welded to adjustable collars (figure 6.6). The supporting deckof the armrest is comprised of 2 4” x 20” x 3/16” flat bar welded on a 90 degree angle with the vertical piece being closet to the side post. The supporting deck is welded to a frame made of 3 pieces of 1”x 1” square tubing. A 10” segment is welded to the collar and to the midpoint of a 20” segment. The 10” segment is braced by a 5” segment welded to the collar and to the bottom of the 10” segment (figure 6.4). Plating was added to the front of the supporting deck to guide the cable of the pulley system. A bracket to house a pulley was welded to the front of the armrest.
The pins that allow for the adjustability of the armrest slide through the collars fix the height of the armrest.The pins are currently loose when removed from the armrest. A small pocket could be added to the collar, or a chain could be welded to the pin and to the collar, to keep prevent the losing the pins.
The armrest would ideally be covered in foam, leather or vinyl padding to reduce the stress placed on the upper arms as they rest on the supporting deck.
Pulley System
The pulley system (figure 4.5, 6.7) consists of two pulleys mounted from the bracket on the top of the frame (figure 5.4). A wiper (figure 5.5, 6.8, 6.9) extends from the bracket and is made of 2” x 10” x 3/16” flat bar. ¼” holes are drilled into the flat bar at either end of the wiper to allow a 1/8” x 2 ½” bolt acting as an axle for the pulleys to pass through(figure 4.6). The cable runs over the top pulley and under the bottom pulley of the wiper to help keep the cable parallel to the ground when in tension. Pulleys were also mounted in a similar manner to the armrests to allow the user to perform additional exercises (figure 7.2).
The cable is a constant length. However, as the height of the armrest changes, the length of the cable required to perform the bicep curl exercise changes. Currently, the problem is solved by adjusting the length of the cable using cable clamps to reduce slack.
Design Setbacks
Several setbacks were encountered during the design and construction process that led to further design iteration and development. Starting with the construction of the frame, the ½” holes drilled into the vertical posts that support the collars were drilled one side at a time because the available drill press did not have sufficient reach to drill through both sides of the square tubing at once. This resulted in holes on either side of each post becoming misaligned. Additionally, the vertical posts were cut to 84” lengths which proved to be 3/8” too long because the thickness of the plates which support the pockets in which the posts are resting in has a thickness of 3/16 at the top and bottom which was overlooked during the design process.
The initial design of the pulley system proved to be faulty and required modification. As the pulley system was assembled, the wiper did not perform its intended function because it allowed for too much slack in the cable without providing suitable resistance during a lift. After several attempts to improve the functionality of the wiper, the idea was rejected altogether. Instead, the wiper is fixed to the top bracket which also supports the top pulley (figure 6.8).
In designing the Cage, the lack of experience resulted in a failure to account for how materials fit together in actuality. During welding, it was discovered that the brackets that had been designed required extra bracing. Miscommunication led to the welder being unaware of which piece was the top and which was the bottom of the frame, resulting in the brackets meant for the top part of the frame being welded to the bottom (6.12). This caused the prototype to be assembled upside down and creating a tripping hazard that had not been present in the design.
Cost Breakdown
Figures 1.1 to 1.8 detail the spending done on costs incurred during construction.
Description / Length / Number of pieces / Unit price / Cost (taxes in)Angle Iron
2” x 2” x 3/16” / 7’
4’ / 4
7 / $2.44/ft / $136.64
Square Tubing
2” x 2” x 0.125” / 7’ / 4 / $3.06/ft / $78.45
Square Tubing
2.5” x 2.5” x 0.188” / 1’
6”
2’ / 2
8
2 / $5.61/ft / $175.32
Flat Bar 3/16” x 2” / 2’ / 18 / $1.28/ft / $46.08
Flat Bar 3/16” x 6” / 4 ½” / 8 / $3.83/ft / $25.02
Pipe 1 ½” / 6” / 2 / 2.64/ft / $31.68
Flat Bar 3/16 X 1 ¼ / $0.56
Flat Bar 3/16 X 4 / $16.27
HSS Square 1X1X0.125 / $8.87
Total (taxes in)
$578.37
FIGURE 1.1, Steelmac Limited Antigonish
Description / Number of pieces / Unit price / Cost(taxes in)3/8” x 1” Bolt / 46 / $0.24/bolt / $11.13
3/8” Nut / 46 / $0.08/nut / $4.09
3/8” Washers / 1 Box (100/box) / $6.89/box / $6.86
Total (taxes in)
$25.43
FIGURE 1.2, Kent Dartmouth
Description / Number of pieces / Unit price / Cost(taxes in)Metal Drill Bit
½” x 6” / 1 / $20.23/bit / $20.23
Metal Drill Bit
¼” x 4” / 1 / $8.27/bit / $8.27
Total (taxes in) $32.77
FIGURE 1.3, Rona Elmsdale
Description / Number of pieces / Unit price / Cost (taxes in)½” Hitch Pin with clip / 2 / $2.99/pin / $6.88
FIGURE 1.4, Princess Auto Dartmouth
Description / Number of pieces / Unit price / Cost (taxes in)Single Pulley / 2 / $10.48 / $20.96
Double Pulley / 1 / $12.48 / $12.48
Total cost (taxes in)
$38.46
FIGURE 1.5, Central Antigonish
Description / Length / Number of pieces / Unit price / Cost (taxes in)Steel cable / 50’ / 1 / $13.99 / $16.09
FIGURE 1.6, Highland Building Supplies Antigonish
Description / Length / Number of pieces / Unit price / Cost (taxes in)Flat Bar 3/16” x 2” / 44” / 1 / $15 / $17.25
FIGURE 1.7, Metals ‘R’ Us Dartmouth
Description / Number of Pieces / Unit Price ($) / Cost ($)(taxes in)Rope Pulley / 2 / 3.29 / 6.58
Wire THMBL / 2 / 1.99 / 3.98
Wire Clip / 4 / 2.39 / 9.56
Hook,Clevis / 2 / 4.99 / 9.98
Secu Snap / 2 / 3.29 / 6.58
Total (taxes in)
42.18
FIGURE 1.8, Canadian Tire
Total Costs (taxes in) = $782.86
Budget was not something that had been placed in high importance during the initial design stages of the Cage. The budget of $400 was unrealistic for the project simply due to the costs of materials.
Conclusion
Gym memberships can be very expensive and it is reasonable for a gym to purchase equipment that tailors to a specific exercise. The machine is an improvement and fills a niche in the advancement in weightlifting technology. A modern piece of equipment that offers many benefits will be well received as a fundamental piece of equipment in gyms everywhere. Gyms are competitive businesses that work by satisfying the gym member’s needs. If a member sees new technology as better way to train the biceps muscles, he or she will pressure the facility to procure the new equipment. Since gyms are competitive, a business with better, newer exercise equipment will invariably be more popular and will receive more customers than one that does not provide the same up to date technology.
The Cage began as a new technology designed to improve the bicep curl. It was necessary to create a design, based on personal knowledge and experience with regards to weightlifting, which would allow for a relatively new weight lifter to perfect the form of the bicep curl and decrease the risks to safely. Though the Cage cost more time and money than had initially been accounted for, the end result is a multipurpose piece of gym equipment that corrects the form of and improves upon the traditional bicep curl while also being a viable market option for both gyms as a service and for home gyms.