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Simon Fraser University
Biomedical Physio & Kines
BPK 143
Tony Leyland

FLEXIBILITY AND STRETCHING - Flexibility is the range of motion (ROM) around a joint - Stretching is a component of exercise programs - The 120-minute run test is also known as the “Copper Test” - Dr.Cooper suggests that, by the time you are 50 years old, 50% of your training should be resistance training - Benefits of stretching include 1) Joint health 2) Reduction of low-back pain and injuries 3) Reduction of DOMS 4) Pain relief 5) Athletic performance 6) Improve posture 7) Relaxation - ROM must be adequate for daily activities WHAT DETERMINES FLEXIBILITY? - Some people have a greater ROM because of the way their bones are shaped - Different joint structures allow different ranges of motion - Normal activity and exercises through full ROM reduce the likelihood of a muscle shortening, and a well designed stretching program can actually lengthen the muscles - With a stretching program, sarcomeres are laid down in series, increasing muscle length - The nervous system plays a role in what range of motion you can achieve by regulating muscle contractions - Reciprocal innervations: takes place when a muscle contracts, inhibiting contraction of antagonist muscles; for example, when hip flexors contract, hip extensors relax - Muscle spindles: these are sensory nerve endings in the muscle that detect muscle length change and rate of change. Force applied to a muscle stimulates muscle spindles, which activate protective reflexes and result in muscle contraction (such as the knee jerk response to neurological testing procedures) - Golgi tendon organ: a tendon organ that is located at the insertion where the muscle fibres insert into the tendon. When the muscle generates force, the sensory terminals are compressed and a signal is sent to the spinal cord which signals the stretch reflex - - - When contracting hip flexors in a hamstring stretch, initially the muscle spindles in the hamstring fire and the muscle contracts to protect it from an excessive stretch - If the stretch is hold long enough, the stretch reflex diminishes and a subject can stretch the muscle out further - Reason why in order to get the full benefit from static strength, you must hold it for more than 20 seconds TYPES OF STRETCHING Static stretching - This method encompasses various techniques that lengthen a muscle to an elongated position (to the point of discomfort), where it is held in position statically for 20-40 seconds - During the holding period, participants may feel a mild discomfort in the muscles - When performed properly, static stretching lessens the sensitivity of tension receptors, which allows the muscle to relax and be stretched to greater lengths - Passive stretching: an external force, such as gravity or push from a partner, moves the limb into the new position - The more force exerted on the limb, the less time it will take to get a substantial stretch - As long as the stretch force is applied gradually, the risk of injury is low - Active stretching: occurs when you move your limb into position by contracting the antagonist muscle: no external force is used. - Reduce the potential for injury - Ballistic stretching: momentum from body parts propels the muscle into an extended range of motion, exceeding an individual’s static, passive stretching ability. These types of stretches are usually initiated by quite vigorous movements - Dynamic stretching: the movement into the stretch position is more controlled and the fully stretched position is often held for one or two seconds. Dynamic stretching involves lower limb belocities than ballistic stretching. - Dynamic stretching is important during warm-up for sports involving dynamic activity Benefits of ballistic stretching include: 1) It develops dynamic flexibility better. Ballistic stretching adheres to the principle of specificity by stressing muscle and connective tissues in manners in which they will be used 2) It has been shown to be effective, although more research is definitely needed 3) It can be performed in unison during team warm-ups, which can help to promote team camaraderie 4) It can be less boring than static stretching CONTROVERSY SURROUNDING FLEXIBILITY AND STRETCHING - More is not always the best - The ideal advice lies somewhere in the middle if flexibility is viewed on a continuum - No flexibility ( anklosis, a stiffness or fixation of a joint through surgery or disease) is highly undesirable - Extreme flexibility or instability can lead to dislocations, poor coordination, and increased risk of joint, muscle and connective tissue injury - Evident that support the notion that stretching can prevent injury is lacking - Those possessing high flexibility and low flexibility, have been shown to be a higher risk of injury - Low flexibility may increase the risk of muscle and tendon injury - High flexibility may increase the risk of ligament and cartilage injury STRETCHING PRIOR TO EXERCISE (WARM-UP) - Warming-up prior to activity is essential, but static stretching should not be part of that warm-up - Five reasons why stretching before exercise would not prevent injuries 1) In animals, immobilization or heating-induced increases in muscle compliance (stretch-ability) causes tissues to rupture more easily 2) Stretching before exercise should have no effect for activities in which excessive muscle length is not an issue , such as jogging 3) Stretching won’t affect compliance during eccentric activity, when most strained are believed to occur 4) Stretching can produce damage to the structures within the muscle fibre 5) Stretching appears to mask muscle pain in humans, and this may increase chances of excessive exercise effort - Caution must be used when doing static stretching perior to hard training as it may weaken the muscle leaving it prone to injury - Warm-up is designed to prepare for the activity to come, reduce the chance of injury, and improve performance, NOT improve flexibility - The warm-up is not about training any particular component of fitness - Increased compliance (stretch-ability) in the tendon (due to static stretching) increases the time required to transmit force from muscle to bone - Static stretching slows you down - Other studies found that static stretching decreases muscle strength by as much as 30% - Stretching the muscle in one leg can reduce strength in the other leg, probably because the central nervous system inhibits input due to the duration of the static stretch - Stretching is most effective when the muscle is warm - It is better to stretch after a run when deep muscle temperature is high, and the muscle and tendon are more compliant Basic stretching program - Must treat stretching as a disruption to muscle homeostasis (resting state) - With a stretching routine, you are trying to force an adaption that would add sarcomeres in series and increase the length of the muscle The ACSM recommends static flexibility training with these variables: 1) A minimum of two to three days per week 2) Holding each stretch for 20-40 seconds to mild discomfort 3) Performing three to four repetitions per stretch 4) All major muscles group must be targeted *remember how to perform stretching for each muscle” Proprioceptive neuromuscular facilitation - An advanced form of flexibility training that involves both stretching and contraction of muscle groups - Excellent for increasing flexibility and can also improve muscular strength - Most common PNF stretching technique is called contract-relax or hold-relax - Muscle group is positioned so that muscles are stretched and under tension - The individual than contracts the stretched muscle group for five to six seconds while a partner or immovable object applied sufficient resistance to inhibit movement, resulting in an isometric contraction - The contracted muscle group is then relaxed, and a controlled stretch is applied for about 30 seconds - The muscle group is allowed 30 seconds to recover and the process is repeated two to four times - Other types of PNF techniques are: 1) Contract-relax with agonist contract (CRAC) 2) Hold-relax-wing/hold-relax bounce rhythmic initiation 3) Rhythmic stabilization - PNF stretching is effective and may increase ROM, but it may be uncomfortable Common orthopaedic inflexibilities - Inflexibilities can easily cause injuries, such as poor hamstring flexibility leading to back problems Additional notes on flexibility exercises - Joints have several muscles crossing them and some can move in many directions, so you usually need to perform more than one stretch per joint - Some stretches should generally be avoided 1) Standing hamstring stretches – put pressures and strain on the lower back 2) Single or double-leg inverted hurdlers stretch- this is when you sit on your lower legs and lean backward to pay your back on the floor. This can result in over-stretching some tissues, crushing others, pinching nerves, and jamming joints 3) Full neck circles- neck extension puts pressure on the cervical disks 4) Arches and bridges (back hyperextension) – any hyperextension of the low back can cause injury. Hyperextension of the low back can jam spinal joints together, excessively squeezing spinal disks. This can also pinch nerve fibres that emerge to form the sciatic nerve 5) Standing torso twist- probably safe as a static stretch, but, when performed dynamically, there is a danger that the momentum gained can exceed the absorbing capacity of tissues being stretched. Ligaments and joints in the lower back are at risk if this exercise is performed too vigorously 6) Gravity inversion- a traction technique that requires special boots or frames. The dangers of gravity inversion are probably limited to those with health problems such as high blood pressure and glaucoma. This is because the exercise will increase blood pressure and pulse, and also increase intraocular pressure BACK FITNESS - The skeletal muscles that support the spinal column need to be strengthened on all sides of the trunk - Core muscles respond to strength and endurance training the same as any skeletal muscle - The spine is an unstable stack of small bones, referred to as an inverted pendulum ( without ligament and muscular support, the spinal column would collapse) - If you take care of the strength and endurance of all major muscle groups and maintain a good range of motion across major joints, you will be far less likely to suffer from low back pain or other problems associated with the spinal column - Most back problems do not occur due to lifting heavy objects - You need to stress the spine and allow it to rebuild itself stronger - While lifting, pulling, and pushing objects are major causes of work-related low-back pain (LBP) and other musculoskeletal injuries, LBP is also common in work environments where no lifting occurs, such as seated work - The pressure within the spinal discs is, in fact, higher when sitting than when standing; so it is not surprising that LBP is also caused by non-work related movements and postures - Sitting for very long periods without moving much, and the loading on the spine is constant for extended periods - Other factor is many people have poorly conditioned trunk musculature, because they spend several hours driving/sitting Anatomy of the spine - The spine is an inverted pendulum- a series of bones separated by fluid-filled disks, are relevant to understanding a core conditioning program. - Only focusing on strengthening trunk muscles is not necessarily going to prevent LBP - Strong but short gluteals and hamstrings may be the cause of a person’s LBP - - No single muscle is the most important muscle for stability, as the required pattern of recruitment varies with each different movement pattern - Muscles that are strong but short can also cause problems if they attach to the core Abdominal Group  Transverse abdominus—Forced expulsion (breathing).  Internal obliques—Lateral flexion, rotation to same side and flexion of trunk.  External obliques—Lateral flexion of trunk to same side, rotation to opposite side, and flexion of trunk.  Rectus abdominus—Flexion of trunk. Back Muscles  Erector spinae—Trunk extension.  Multifidus—Lateral flexion, extension, and hyperextension of the spine. (In 2000, Kader, Wardlaw, and Smith found mutifidus atrophy in 80% of patients (n=78) with back pain—bilateral in most cases.)  Quadratus lumborum—Highly involved in lumbar spine stabilization; largely isometric.  Latissimus dorsi—Spine stabilizer enhanced by pulling to chest in lat pull-down exercise. Core conditioning - Whenever you are upright in a gravitational field and/or move, you recruit your core - Without good core development, you will not be able to move and react efficiently - Pretty much all movement and exercises recruit the core - Safety loading your body with large weights stimulates hormonal responses such as increased growth hormone, testosterone, and insulin-like growth factor - This will help improve hormonal balance, strength, and core stability - No matter how well coordinated you are, if the load on your spine overwhelms your strength, the spine will buckle - “if the work done on the spine (energy applied) is greater than the work the muscles can do to stiffen the spine, then the spine will buckle - The current view that the core is only engaged on unstable surfaces is mechanically incorrect - When on a unstable surface, the total body stability is challenge, not spinal stability specifically -
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