Compression Clothing

Compression garments which include socks, pantyhose, sleeves, etc., are very popular for people doing exercise during last 2 decades. Athletes usually wearing these clothes to obtain a different level of compression. Many people say that this kind of clothing could improve performance, help recover after exercise and reduce swelling. However, does it works for every kind of exercise? How does it work?

Figure 1: Example of a Compression Clothing

Physiological Effect

On one hand, wearing compression clothes could benefit form its physiological effect. Scientists find that wearing compression clothing dose not improve cardiorespiratory performance during endurance training, but it could increase local blood flow and increase the clearance of metabolites and the supply of nutrients. Also, wearing compression clothing during long lasting exercise can improve performance which reduces fatigue level by attenuating maximal lactate concentration in the blood. However, during short lasting exercise such as 60m sprinting, wearing compression garments does not increase speed, but it helps recover by quickly reduce blood lactate level in following 10 minute after exercise.


Physical Effect

On the other hand, wearing compression clothes also have physical benefits. It could be considered as a spring that helps muscle contraction. During our movement, muscle uses contractive force to provide torque at joint in order to move our body. Wearing compression garments results in a considerable torque being generated about the joint at the flexion and extension ranges of motion. This could reduce injury and enhance muscle performance during exercise such as jumping. During swing phase, the risk of hamstring injury is increased the clothes can provide a torque that reduces the burden of the muscle, and during jumping phase, it provides a contractive force, so that the person can jumper higher.

Figure 2: Wearing Compression Garment During Jumping Exercise


While looking at the papers that I found, the studies are made very specific to each exercise. Wear compression clothes leads to different performance improvement and blood lactate and lactate dehydrogenase lever during and after exercise. In general, wearing compression garment is beneficial which helps reduce muscle and blood lactate level and increase blood flow rate. It also helps improve performance by adding torque required for movement at joints. The clothes is also temperature resisting, it helps retain local body temperature as well. However, it does not improve performance for all exercise, so use it wisely.


Products recalled for children’s


Many furniture was designed harmful for children, many children were injured or killed due to tip over of the furniture. Dressers designed like this (fig. 1) has killed 7 children and got many injured. In 2016, IKEA recalled many dressers that have potential to tip over while kids climbing it. For a 8-year-old child, is it possible to tip the dresser over when climbing? Unknown: sum of the moment at the center of tip-over.


(fig. 1: dresser tip over due to defect)

(fig 2: information of one of the dressers IKEA recalled in 2016)


Goal: find the moment at point O.

Formula to use: M = F*d(perpendicular)

The dresser is 134 cm tall, and 48 cm deep. Width is not necessary to measure since we are using a 2-d model.

First, we set up a 2D model to solve the problem (fig. 3).

O: point of tip-over. A: center of mass of the child. B: center of mass of the 3 drawers inserted. C: center of mass of the dresser (without drawers). D: center of mass of the top drawer that is out.

Drawers are 9.25 kg each. Dresser without drawer is 35.97 kg. Mass of a 8-years-old child: 23 kg. A(-55, 75), B(24,50), C(24,67), D(-24, 100)

Assumptions: the dresser is uniformed in weight. weight of the foots and top are negligible. No other things in the drawer. The top drawer is fully out and other drawers are fully inside. Center of mass occur at the geometric center of the main body.

(fig. 3 2-D model for the problem.)


ΣM= 28 kg* 9.8N/kg* -0.55m+3*9.25kg* 9.8N/kg* 0.24m+35.95kg* 9.8N/kg* 0.24m+9.25kg* 9.8N/kg* -0.24m = -150.92+65.27+84.56-21.76=-22.85N-m

The answer implies that a 8-year-old child is able to tip the dresser over by climbing on the top of the drawer. We assumed that the dresser is empty, and uniformed in weight. However, in real-life the problem could be more specific. Also we simplified the problem as a 2-D problem which implies that the dresser would only tip to the left, but in 3-D world the it could tip at any angle. Further, only one case which the child hangs one the top drawer with other drawers inserted was analyzed, but many other situation could happen in real-life.

The answer is reasonable since all values used were real-life values, and that is why the products were recalled.

In this case, any child weighs over 26 kg has potential to tip over the dresser and get injured or killed.



Patent title: Wrist exercise device

Patent number: US3924851 A

Patent filing date: Oct 25, 1974

Patent issue date: Dec 9, 1975

Inventor(s): Winston Herbert

Assignee (if applicable): Winston Herbert

U.S. classification:  482/105

Claims: 1

FIG. 1 is a perspective view illustrating the

exercise device in its wrist-encircling position;

FIG. 2 illustrating the

inside surface thereof, i.e. the surface against the user’s

wrist, and

FIG. 3 the outside surface; and

FIG. 4 is an end elevational view showing details of

the device in its wrist~encircling condition.

FIG. 5 is a perspective view of another embodiment

of the wrist exercise device hereof.

The wrist exercise device is generally a wrist band that is comfortable to wear. It consists of 2 parts, fabric body and metal rods as weights. The weight of the device is adjustable by adding or removing metal rods on the band. It also can be wear around the ankles and it is easy to make exercise more strenuous.

This invention could be used by anyone that wish to add some intensity to their exercise; also, it could be used to help patients accomplish recovery training.

While wearing this product on the end of limbs, depends on how much weight the user loads, it could help the user build muscle by lifting extra weight. For patients, it could be used while passive training by helping them stretch muscle groups or joints; also, it can be used as extra weight for patient to do active exercise.

Comparing to traditional free weights, this device is designed wearing on limbs, so it does not require users to constantly using hands to hold it. Also, it is comfortable to wear, portable, and adjustable.

The reason that I chose this patent is that this wrist exercise device is simple; however, it is has many advantages comparing to traditional free weights which are extremely easy to use, more portable, adjustable, and it could be used almost every class of people.