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Anatomical features that help humans run

Here are anatomical characteristics that are unique to humans and that play a role in helping people run, according to the study:

Skull features that help prevent overheating during running. As sweat evaporates from the scalp, forehead and face, the evaporation cools blood draining from the head. Veins carrying that cooled blood pass near the carotid arteries, thus helping cool blood flowing through the carotids to the brain.

A more balanced head with a flatter face, smaller teeth and short snout, compared with australopithecines. That "shifts the center of mass back so it is easier to balance your head when you are bobbing up and down running", Bramble says.

A ligament that runs from the back of the skull and neck down to the thoracic vertebrae, and acts as a shock absorber and helps the arms and shoulders counterbalance the head during running.

The tall human bodywith a narrow trunk, waist and pelviscreates more skin surface for our size, permitting greater cooling during running. It also lets the upper and lower body move independently, "which allows you to use your upper body to counteract the twisting forces from your swinging legs", Bramble says.

Shorter forearms in humans make it easier for the upper body to counterbalance the lower body during running. They also reduce the amount of muscle power needed to keep the arms flexed when running.

Long legs, which chimps and australopithecines lack, let humans to take huge strides when running, Bramble says. So do ligaments and tendonsincluding the long Achilles tendonwhich act like springs that store and release mechanical energy during running. The tendons and ligaments also mean human lower legs that are less muscular and lighter, requiring less energy to move them during running.

 

Skateboarding

Skateboarding is the act of riding and performing tricks using a skateboard. A person who skateboards is most often referred to as a skateboarder, or colloquially within the skateboarding community, a skater.

Skateboarding can be a recreational activity, an art form, a job, or a method of transportation. Skateboarding has been shaped and influenced by many skateboarders throughout the years. A 2002 report by American Sports Data found that there were 18.5 million skateboarders in the world. 85 percent of skateboarders polled who had used a board in the last year were under the age of 18, and 74 percent were male.

Skateboarding is relatively modern. A key skateboarding maneuver, the ollie, was developed in the late 1970s by Alan "Ollie" Gelfand as a half-pipe maneuver. Freestyle skateboarder Rodney Mullen was the first to take it to flat ground and later invented the kickflip and its variations.

Culture

Skateboarding was, at first, tied to the culture of surfing. As skateboarding spread across the United States to places unfamiliar with surfing or surfing culture, it developed an image of its own. For example, the classic film short Video Days (1991) portrayed skateboarders as reckless rebels.

The image of the skateboarder as a rebellious, non-conforming youth has faded in recent years. Certain cities still oppose the building of skateparks in their neighborhoods, for fear of increased crime and drugs in the area. The rift between the old image of skateboarding and a newer one is quite visible: magazines such as Thrasher portray skateboarding as dirty, rebellious, and still firmly tied to punk, while other publications, Transworld Skateboarding as an example, paint a more diverse and controlled picture of skateboarding. Furthermore, as more professional skaters use hip hop, reggae, or hard rock music accompaniment in their videos, many urban youths, hip-hop fans, reggae fans, and hard rock fans are also drawn to skateboarding, further diluting the sport's punk image.

Films such as Grind and Lords Of Dogtown, have helped improve the reputation of skateboarding youth, depicting individuals of this subculture as having a positive outlook on life, prone to poking harmless fun at each other, and engaging in healthy sportsman's competition. According to the film, lack of respect, egotism and hostility towards fellow skateboarders is generally frowned upon, albeit each of the characters (and as such, proxies of the "stereotypical" skateboarder) have a firm disrespect for authority and for rules in general. Group spirit is supposed to heavily influence the members of this community. In presentations of this sort, showcasing of criminal tendencies is absent, and no attempt is made to tie extreme sports to any kind of illegal activity.

Gleaming the Cube, a 1989 movie starring Christian Slater as a skateboarding teen investigating the death of his adopted Vietnamese brother was somewhat of an iconic landmark to the skateboarding genre of the era. Many well-known skaters had cameos in the film, including Tony Hawk.

Skateboarding video games have also become very popular in skateboarding culture. Some of the most popular are the Tony Hawk series, and Skate series for various consoles (Including hand-held) and personal computer.

 

Sailing

Sailing is the art of controlling a boat with large (usually fabric) foils called sails. By changing the rigging, rudder, and sometimes the keel or centre board, a sailor manages the force of the wind on the sails in order to change the direction and speed of a boat. Mastery of the skill requires experience in varying wind and sea conditions, as well as knowledge concerning sailboats themselves and local knowledge with regards the area one is sailing in.

While there are still some places in the world where sail-powered passenger, fishing and trading vessels are used, these craft have become rarer as outboard and modified car engines have become available even in the poorest and most remote areas. In most countries people enjoy sailing as a recreational activity or as a sport. Recreational sailing or yachting can be divided into racing and cruising. Cruising includes extended trips, short trips within sight of land, and daysailing.

Throughout history sailing has been instrumental in the development of civilization, affording mankind greater mobility and capacity for fishing, trade, and warfare. The earliest representation of a ship under sail appears on a painted disc found in Kuwait dating to the late 5th millennium BC. Advances in sailing technology from the Middle Ages onward enabled Arab, Chinese, Indian and European explorers to make longer voyages into regions with extreme weather and climatic conditions. There were improvements in sails, masts and rigging; navigation equipment improved. From the 15th century onwards, European ships went further north, stayed longer on the Grand Banks and in the Gulf of St. Lawrence, and eventually began to explore the Pacific Northwest and the Western Arctic. Sailing has contributed to many great explorations in the world.

Sail trimming

Sail trimming is a large subject and a matter of debate. The most basic control of the sail consists of setting its angle relative to the wind. The control line that accomplishes this is called a "sheet." If the sheet is too loose the sail will flap in the wind, an occurrence that is called "luffing." Optimum sail angle can be approximated by pulling the sheet in just so far as to make the luffing stop. Finer controls adjust the overall shape of the sail.

Two or more sails are frequently combined to maximize the smooth flow of air. The sails are adjusted to create a smooth laminar flow over the sail surfaces. This is called the "slot effect". The combined sails fit into an imaginary aerofoil outline, so that the most forward sails are more in line with the wind, whereas the more aft sails are more in line with the course followed. The combined efficiency of this sail plan is greater than the sum of each sail used in isolation.

Hull trim

Hull trim is the adjustment of a boat's loading so as to change its fore-and-aft attitude in the water. In small boats, it is done by positioning the crew.

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