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Introduction
Flat feet is the most common foot deformity known. In fact, sixty million Americans or 25% of the U.S. population have flat feet [1]. Some of these people may experience problems that limit their activities, while others can run marathons or play in the NBA. The good news is that the vast majority of cases, especially in children, require only conservative (non-surgical) treatment, if any at all.
What is Flat Feet?
If you've ever seen your footprints in the sand and they looked more like bricks than feet, then you probably have flat feet. Simply stated, a flat foot is a foot that does not have an arch when standing. In the medical world, flat feet are associated with "pronated" feet. Pronated is merely the term used to describe the position of the foot when it is flexed upward (dorsiflexed), turned away from the body (abducted), and the heel is rolled outward (everted), all at the same time. A certain amount of pronation is required for normal walking, but too much pronation is often considered a foot's "worst enemy." Over time, excessive pronation can lead to many unpleasant problems including heel pain, bunions, hammertoes, shin splints, and even knee, hip, or back pain. In fact, in his private practice, orthopedic surgeon Dr. Pryce discovered that 95% of his total knee replacement patients and 90% of his total hip replacement patients had flat feet [1]. An easy way to tell if you pronate too much is to take a look at your athletic shoes-excessive wearing of the inside heel (arch side of the shoe) as compared to the outside is a classic indication of excessive pronation.
The normal foot is made up of 28 bones, 30 joints, 128 ligaments, 22 muscles, and 49 tendons. These structures are all arranged in such a way as to be rigid enough to support the weight of the body at certain times, yet flexible enough to conform to the contours of the ground and absorb shock at others. During every step taken while walking or running, the foot switches from rigid to flexible and back to rigid. The focal structure of this ability is the arch. When the arch is high, the foot is rigid for support or pushing off. When the arch is low (as occurs with pronation), the foot is flexible for conforming. So you see, if the arch is fixed in a position too high or too low, or if it is unable to switch back and forth, the foot cannot function properly.
کم آبی و آسیب مغزی
dehydration & brain damage
Brain damage risk from dehydration
Dehydration leads to changes in the volume of compartments within the cranium that could put sportsmen and women at risk of brain damage after head injuries, according to a team of UK researchers (‘The effects of dehydration on brain volume – preliminary results’, International Journal of Sports Medicine 2005; 26:481-485).
In adults, the cranium (the part of the skull that encloses the brain) is a rigid bony vault of fixed size, with a constant volume that is the product of the volume of the brain, the intracranial cerebrospinal fluid (CSF) in a compartment known as the subarachnoid space, and the intra- cranial blood. The brain is suspended within the sub-arachnoid space, which surrounds it with a protective cushion of fluid. The brain itself contains fluid- filled cavities known as the cerebral ventricles, which communicate with the subarachnoid space.
The aim of this pioneering study was to investigate the relationship between dehydration and changes in the volume of the brain and the cerebral ventricles in six healthy male amateur rugby union players.
The subjects underwent magnetic resonance imaging (MRI) scans of the brain before and after a period of exercise designed to cause significant dehydration, while samples of blood and urine were taken before and afterwards to assess the degree of dehydration. One of the subjects (control) undertook a further series of MRI scans to enable the researchers to assess day-to-day fluctuations of brain and ventricular volume in a normally hydrated healthy person.
They found that the subjects lost between 2.1% and 2.6% of their body mass from sweating during the exercise. They also found a correlation between the degree of dehydration and the change in ventricular volume, with changes in the latter much larger than those seen in the normally hydrated control subject.
‘Changes in the volume of the brain, the intracranial CSF (especially the subarachnoid space) and the intracranial blood may influence the outcome of closed head injuries,’ the researchers explain. ‘After an impact to the head the brain will travel further within the cranium before it meets the skull if the subarachnoid space is enlarged than in the normally hydrated state. Consequently it will accelerate to higher velocities and this may increase the likelihood of contusion injuries after blows to the head such as those sustained in boxing, football and rugby’.
Although the researchers acknowledge that their study was too small to be definitive, they conclude that dehydration causes changes in the volume of intra-cranial compartments that may put sportsmen and women at increased risk of brain damage from contusion injury (bruising) and internal haemorrhage after head injuries.
‘Some sportsmen and women, eg boxers, rugby players and footballers, are especially vulnerable to
کشش و انعطاف پذیری
Why you need to stretch
Flexibility is important because having flexible muscles allows your joints to move through a full range of motion. You need a certain amount of flexibility to move smoothly, avoid muscle tension and to keep your body protected from injury.
Stretching is one way to keep the body flexible, especially the muscles that are tight as a result of bad posture. Although stretching is typically the most overlooked part of an exercise routine, it's an important one and, for many of us, the best part of the workout.
Why Should You Stretch?
You'll improve your performance and reduce your risk of injury
You'll reduce muscle soreness and improve your posture
You'll help reduce lower back pain
You'll increase blood and nutrients to the tissues
You'll improve your coordination
You'll enjoy exercise more and help reduce stress
How to Stretch
1. Your best bet is to stretch after your workout when your muscles are warm and you're ready for a cool down.
You don't have to stretch before your workout but, if you do, make sure you do it after the warm up. Stretching cold muscles can cause injury.
2. When doing static stretches, don't bounce. Hold a comfortable position until you feel a gentle pull on your muscle. It shouldn't hurt and bouncing could cause you to pull a muscle.
3. Try to hold each stretch for 15-30 seconds to get some long-term flexibility benefits.
4. You can also stretch between strength training sets and you may want to perform light stretches throughout the day to deal with tight shoulders, neck and lower back.
When you stretch after the workout, try to hit all the muscles you used, paying close attention to any chronically tight areas.
Yoga
Yoga is another way to stretch your body while also working on balance, endurance and stress relief. Adding yoga to your routine a few times a week is a nice compliment to strength training and cardio, giving you a gentle, soothing way to work your body and mind
