Skip to 0 minutes and 6 seconds Football players and supporters will know how effective an old-fashioned cold soggy sponge can be in treating a bruised ankle on a chilly winter’s day. Some injured footballers miraculously return to action within just a few seconds of treatment! For those more seriously injured, the ‘magic sponge’ will, unfortunately, not work and other more scientific approaches are needed. Whereas repairing muscle or ligament tear may require surgery, for more minor injuries, ‘chemical magic sponges’ are often effective. Today, qualified physiotherapists carry bags with a wide array of sprays, tablets, gloves and bandages, which are designed to deal with professional athletes’ injuries. A particularly common injury is a minor bruise or an ankle or elbow sprain.
Skip to 0 minutes and 55 seconds To treat such injuries a cold spray is often used, which acts to deaden the pain and also reduce the swelling. Hydrocarbons, such as butane and 2-methylpropane (or isobutane), are popular ingredients as they have low boiling points. In aerosol cans the hydrocarbons are stored at 2-8 times normal atmospheric pressure - when you let a gas escape from 8 times its normal pressure into the air, it expands enormously and cools down drastically, hence the cooling effect when sprayed on an injury. In contact sports such as football, hockey and rugby, cuts and scrapes are particularly common. To treat these injuries, antiseptic sprays are commonly used. These sprays provide relief by soothing and numbing the area while helping to prevent infection.
Skip to 1 minute and 43 seconds Active ingredients include local anaesthetics such as lignocaine (lidocaine), which act by blocking nerve impulses from reaching the brain. Once inside the nerve cell, the amine group of lignocaine is protonated, and the positively charged lignocaine molecule then moves into a sodium channel. Sodium channels allow Na ions to move
Skip to 2 minutes and 5 seconds inside and outside the cell: they are crucial for nerve transmission. To transmit a nerve impulse along a nerve, sodium ions move through the cell membrane to the inside of the cell through the sodium channel. But if a protonated lignocaine molecule is in the way, the movement of sodium ions is blocked and the nerve impulse cannot be transmitted to the brain. The pain from acute injuries, such as ligament sprains and muscle strains, is thought to be due to the body’s inflammatory response following the injury. The body responds by clearing away injured debris and dead cells, to make way for the healing process to start.
Skip to 2 minutes and 46 seconds Pain and swelling caused by the inflammation also keep the athlete from using the injured part and protect it from further injury. However, it is thought that the inflammatory response is often excessive and prolonged and, as a result, anti-inflammatory drugs are used to minimise the body’s response. The most common of these are non-steroidal anti-inflammatory drugs (or NSAIDs), such as ibuprofen. Ibuprofen works by preventing an enzyme (called cyclooxygenase) from making compounds called prostaglandins. We produce prostaglandins in response to injury and these would otherwise go on to cause pain, swelling and inflammation. Ibuprofen has a chiral centre and it is sold as a racemic mixture, or a racemate - which is a mixture containing equal amounts of each enantiomer.
Skip to 3 minutes and 33 seconds At first sight this is surprising as only one of the enantiomers is the biologically active component, which is responsible for stopping prostaglandin formation. Interestingly, within the body, there is an enzyme that converts the biologically inactive enantiomer into the active enantiomer. As it is easier and cheaper to produce a racemic mixture, there is little point in looking to market the single biologically active enantiomer. A much more controversial treatment of inflammation is the use of cortisone injections. Cortisone is a steroid present in the body, which has completely different actions to the anabolic steroids used to enhance sports performance. Cortisone is a potent anti-inflammatory drug that can be used to treat certain joint, ligament or tendon injuries where there is lots of inflammation.
Skip to 4 minutes and 22 seconds But cortisone injections must be used with caution. Repeated cortisone injections were at times used in the joints (often knees) of professional athletes to keep them playing rather than attending to the underlying problem. There is still debate about the effectiveness of these injections today. Going forward, further scientific investigation, comparing new products or treatment methods to the current standards of care, will no doubt lead to innovations that provide more effective treatments, which are cost-effective, returning athletes to the playing field even quicker than before.
Understanding medicines in sport
To protect cuts and abrasions, traditionally, flexible cloth bandages are used. These are typically made from cotton. After scouring and bleaching, cotton is 99% cellulose. Cellulose is a polymer made up of a long chain of glucose molecules all linked together by C-1 to C-4 oxygen bridges, called glycosidic bonds, formed on elimination of water. The cellulose chains within cotton fibres tend to be held in place by hydrogen bonding, which occurs between the hydroxyl groups (–OH) of adjacent sugar molecules.
Today, an alternative to cotton is ‘spray on bandage’ or liquid bandages. The spray contains a polymer such as PVP/VA, which binds to the skin and forms a temporary protective coating over the injury. It is easy to remove the bandage because the polymer is water-soluble. When water is applied it dissolves! Liquid bandages can stick better than plastic or fabric adhesive bandages to many hard-to-bandage areas, including knuckles and between fingers.
Research in this area continues, and a new algae-based polymer, called Vetigel, has been developed that stops profuse bleeding within seconds. It was invented in 2010, by Joe Landolina, when he was just 17 years old. (This reminds me of Maria Elena Grimmett who, at the age of just 14, became the youngest person published in the Journal of Environmental Quality for designing reusable polymer beads to remove sulfamethazine (an antibiotic) from rivers, streams and groundwater.)
What sporting injuries would you most like to solve using chemistry-based inventions?
To cool or not to cool, that is the question
As mentioned in the video, cooling the site of an injury, or cryotherapy, is often used to treat acute sports injuries. Putting an ice pack on a pulled muscle can help to relieve pain and is called cooling-mediated analgesia (or pain relief). But how effective is it? Unfortunately, the lack of appropriate randomized and blind model studies means that we cannot definitively say how effective cryotherapy is. It is generally advised to continue to use such therapy soon after acute sports injuries and their surgical treatment. Does adding an ice-pack or cold-spray work for you?
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