Brazuca: Even NASA tested the ball of Brasil 2014 world cup.

World cup just began and all the world turn around the Brazuca, the official of the 2014 FIFA world cup. The ball is manufactured in Pakistan by the sport label ADIDAS.

Besides it 69 cm circumference and it 437 grams, what is special about Brazuca compared to other balls?

Unique aerodynamic
There is some controversy about the effect of wind on the game. Especially the Jabulani ball (2010 world cup) was severely criticized about its aerodynamics and its erratic movement. ADIDAS states that aerodynamic problems will not be present in the Brazuca due to its six identical locking patches that makes it the most spheric ball. The previous Jabulani had eight non-identical patches and the classic balls have 32 hexagonal patches.

Even scientists from NASA had tested the aerodynamics of the Brazuca. NASA tested the Brazuca through a wind tunnel and analyzed its aerodynamics at different speeds.

The roughness of the material and the 6 thermally bonded locking patches increase the seam length; such characteristic along with the roughness of the micro-textured surface improved the aerodynamics and eliminates the erratic movement of Jubulani. Its will produce faster speed and maintain the shape and weight of the ball.

Video 1. NASA tested the aerodynamics of Brazuca
Source: Bloomberg

Why Brazuca?
The name Brazuca was selected by a public vote conducted on line in 2012. It is an informal description of the Brazilian way of life. The other names considered in the vote were Bossa Nova (A very famous genre of Brazilian music) and Carnavalesca (due to the fame of the Brazilian carnival).

The colours and ribbon design of the ball panels symbolize the traditional multi-coloured wish bracelets (fita do Senhor do Bonfirm da Bahia) worn in the country, in addition to reflecting the vibrancy and fun associated with football in Brazil.

Image. Brazuca ball

References & further reading
ADIDAS brazuca, tried and tested
Brazil ready for made in Pakistan Brazuca ballas
Testing the world cup ball in a NASA wind tunnel
Feet on with ADIDAS brazuca

Body fat estimation using bioelectrical impedance

I like excersice and I like fitness. Many times I have comments from friends about the body fat and I also found many people misussing the Bioelectrical Impedance Analysis (BIA). Actually some people don't even know what the BIA is and still use it.

Image 1. Person using a BIA
Image source: Excercisebiology

BIA and body fat estimation

The BIA is a widely used method for estimating body composition, especially the body fat. Despite the general idea that BIA gives you the body, it does not measure the body fat. The BIA determines the electrical impedance of body tissues (opposition of a conductor to the flow of an alternating current), which provides an estimate of the total body water (TBW).

The impedance measured by BIA allows to estimate the body fat (BF), the fat free mass (FFM) and the body cell mass. Several studies analyzed suggested empirical equations developed by analyzing the physical characteristic of different populations; hence, they have different predictive accuracy.

Image 2. Comparison of predictive accuracy of different equations for estimating BF
Image source: Kao et al., 2010

Some suggestions before using BIA
Some suggestions about the use of BIA for estimating your body fat.
Firm holding with of the BIA device.
BIA will not provide the real body fat, but it does provide a reasonable guide. BIA does not provide the exact body fat, but it will indicate in you maintain a stable body fat, or if you tend to increase or reduce your body fat.
Use the BIA at the same time. Our metabolism changes during the day. Impedance when we wake up is different than the impedance at noon of at night.
Do not eat before BIA. Food intake, its absorption and the resulting increase in movement of fluid into the bloodstream from 2–4 hours before BIA measurement, decreases the impedance value and underestimates the body fat.
Use BIA before exercising. Moderate exercise before using the BIA decrease the impedance and will underestimate the body fat. Underestimation due to exercise is twice the one due to eating.
Use BIA under the same (or t least similar) environmental conditions. Different environmental conditions may change the skin temperature and lead to different impedance.

Refernces & Further Reading
Bioelectrical impedance analysis in body composition measurement
Comparisson of different measurement equations for body composition estimation in male athletes