Monday, 13 May 2013

The A - Z of Sports Vision - Long Loop Reflexes

There are several different kinds of reflexes in the human body. Short loop reflexes involve just one nerve junction or synapse. An example is the well-known knee-jerk reaction. This occurs if a leg, swinging free, is tapped at the patellar ligament, just below the knee. A nerve signal is sent to the spine that the ligament has gone slack, as happens when you start to fall over. This signal reaches the spinal cord where, on the other side of the synapse, a responding nerve signal is sent out to make the quadriceps muscle contract. If you were falling, this would propel you into the air and give you a chance to regain your balance. When the doctor does it, you just kick your leg out. But there are also reflexes which involve several synapses. An example is the withdrawal reflex that ensures that you move your hand away rapidly if you touch a hot object. Pain receptors in the affected area send a nerve impulse to the spinal cord, which relays the message to the nerves that control flexor muscles in that area. A third nerve impulse results in that part of the body withdrawing from the painful stimulus. All this takes about half a second, before you are consciously aware that it’s happened. In sport, the connection between the stimulus and the reflex is usually less direct, for example a goalkeeper having to adjust to save a deflected shot. These kinds of actions are known as long loop reflexes because they have some involvement of the brain, rather than just in and out of the spinal column. Wayne Gretzky is generally acknowledged to have been the greatest ice hockey player ever. He played in the National Hockey League for 20 seasons, and holds the career record for total points scored (goals and assists) and assists. And yet Gretzky was always the runt of the team. Small, skinny, slow and with a weak shot. He didn’t even have the most accurate shot, although he was accurate. But he was the fastest at initiating a shot when he saw the opportunity to score, such as from a rebound. He also had the fastest long loop reflex times of anyone examined at the University of Columbia laboratories in Canada. It’s possible that these exceptional reflexes were just a genetic fluke. However it’s also possible that stimulation, particularly at a young age, is crucial. And there are few better examples of stimulation at a young age than Wayne Gretzky. Almost as soon as he could walk he was sliding around the floor in his socks, pretending to skate. He was skating on ice at the age of two on a frozen river that ran through his grandparents’ farm. He practised shots with a rubber ball and a cut-down hockey stick. His father built a rink in the family’s back yard and invited the neighbouring kids to play where he spent thousands of hours. He was ready to play junior league hockey at the age of 5, but had to wait until he was 6 before a team would take him, even though the minimum age was supposed to be 10. When he was 10, he scored 378 goals in a season. Asking how much of a player’s success is down to nature and how much to nurture is like asking how much of the flavour of a cake is down to its ingredients and how much is due to the cooking. But it seems highly unlikely that Gretzky would have been as good a player if he had not had essentially unlimited practice time in those early years. And the same is probably true of those exceptionally fast long loop reflexes. David Donner