Warm Up and Stretching for Aerialists and AcrobatsThere is a lot written and spoken about the need or benefits of warm up and stretching; what should you do, should you stretch at all, static or dynamic stretching, pre or post workout or both? This article describes some of the physiological processes involved in stretching to help you understand what happens and to give you some ideas of what you should look for if you want more in depth information. The principles expressed here can be applied to all forms of exercise although I have tried to keep the warm up and stretching exercises relevant to circus activities. I have also included some links to relevant research where I have used it so again, if you want to do further reading, you have a starting point.
So why warm upAn effective warm up will prepare you for the exercise you are about to perform and will reduce the risk of injury. The primary purpose is to raise your body temperature, increase your heart-rate and your respiration rate ready for the exertion to come. An elevation in body temperature increases the rate that oxygen will be released from haemoglobin and myoglobin, an increase in muscle blood flow, a reduction in muscle viscosity, an increase in the sensitivity of nerve receptors, and an increase in the speed of nervous impulses.(1) Possibly the best piece of research regarding the benefits of warm up and stretching that I have seen was carried out in Norway by Torbjørn Soligard et al (2), based on the FIFA 11+ (3) warm up protocol which demonstrated a 30 to 50% reduction in severe injury in participants. This relates to football but it is obvious that the research can be applied to all activities. Of course it also helps to get you “switched on” and thinking about the exercise you are about to take part in.
First some science – What is a stretch?The sensation of a stretch is the result of the activation of a number of sensory receptors in the muscle belly and muscle tendons. The receptors in the muscle belly are called muscle spindles, and there are two different types that respond slightly differently to the length and velocity of the stretch. Their action is broadly to increase the stiffness of the muscle fibres to resist the stretch serving, in part, to protect the muscle from “over stretching”. It is these muscle spindles that also regulate a process called reciprocal inhibition that you may be aware of. This is a process where the nerve fibres in the active muscle sense the contraction and at the same time “switch off” the ability of the opposite muscle to contract. So as you contract your bicep you triceps relax / lengthen. The second receptor is located in the tendons and has fibres crossing from the tendon into the muscle. These Golgi tendon organs also respond to the amount of stretch through a muscle and respond throughout the stretch of the muscle providing feedback to the nervous system which helps to regulate the amount of stretch a muscle will experience. The Golgi tendon organs regulate muscle tension through a process called the autogenic inhibition reflex. This is a feedback process which as the Golgi tendon organ is activated triggers a response at the spinal cord which inhibits, stops, the muscle fibre contraction. It was thought that this process was only triggered under maximal or post maximal load. It is now thought to be active throughout muscle contraction with each tendon organ regulating groups of muscle fibres helping to balance the load through the whole muscle. Further reading can be found at http://neuroscience.uth.tmc.edu/s3/chapter02.html
Now for the practical bit: Suggested pre activity sequenceWarm up This part should last approximately 5 minutes, but no more than 10. At the end of this period you should be breathing a little harder and should feel that your heart rate has increased. Working in a small area, to prevent over exerting, start moving slowly, only a little above walking pace and gradually building the pace to 30 to 40% of what you may consider maximal. Introduce change of direction, backwards, sideways and in zigzags. Introduce some arm movements while still running: e.g. arms out to the side making small circles gradually building to bigger and bigger circles and reducing back down again. Change the directions of the circles and get the arms going in opposite directions. Arms across the body and out to the sides, changing which arms are on top. Any movement or exercise that involve the whole body and that can be done in a small area can be used; all running and jumping exercises or games just remembering to limit your exertion levels so you warm up but are not working at full potential or maximal exertion. Dynamic Stretching There are 2 types of dynamic stretching: active and ballistic stretching. Ballistic stretching includes rapid, alternating movements or ‘bouncing’ at end-range of motion; however, because of increased risk for injury, ballistic stretching is no longer recommended (4, 5). Active stretching generally involves moving a limb through its full range of motion to the end ranges and repeating several times. It is this second type of stretching that is now widely recognised as most beneficial prior to exercise to reduce the risk of injury. A typical sequence may start with a series of jumping exercises: 1 Stiff legged jumps making most use of the calf muscles. 2 Bounding 2 footed jumps, starting to involve more of the hamstrings, glutes and quads. 3 Hopping, short and high or long and low 4 Start from a crouched position and explode to a star shape, again activating hamstrings, quads and glues but also starting to stretch the adductors of the inner thigh and the muscles of the back and shoulders. • Make sure you squat and keep your heels on the floor to ensure you are getting a stretch through the calf 5 Assisted jumping; now we begin to really exert all of the muscle groups for the jumper but also start to exercise the upper body of the lifter. • Lift from in front or behind with jumper jumping from both feet on the ground. • Add rotation by taking a single arm and helping the jumper travel as far as possible while completing at 180 degree turn. Jumper this time jumping from a single leg. 6 Start to do more for the upper body (e.g. Wheel barrow races.) 7 Press-ups with dynamic arm position changes; wide to narrow to spider man to clap. • Do these types of exercise slowly and with control, ensure that you complete the full range of movement. • Change the arm position, try doing it wide armed; try with both arms moving at the same time so it becomes more of a “jump” type movement; try it in a reverse plank position. 8 Move into rolling exercises: Forward rolls, backwards rolls, rolls over one shoulder. • Add partial rolls but moving to pike positions or fully extended positions, e.g. lying on your back role onto your shoulder and extend legs into the air or pike with straight legs back over the head. There are hundreds of exercises that can be used for this part of your warm up. The important points to remember are: 1 Emphasise the full range of movement 2 Concentrate on the muscle / muscle group you are targeting and make sure that is where the exercise is felt 3 Choose exercises at a level you can complete 4 Keep this section to about 15-20 minutes: you don’t want to be tired, just warm and ready for the planned activity. Activity specific preparation Now you can begin any activity specific warm up work. This is where if you are using equipment the exercises should be done on the equipment or if you are working with a partner exercises should be done together. This should take another 10 to 15 minutes and should lead easily into the activity you are training. Complete basic moves and techniques that the participants can perform in a controlled manner before going onto the core of your session and the more technical and challenging exercises. The contentious bit! Static stretching: Static stretching is, as it suggests, is a stretch done by extending a joint to a point where the muscle crossing that joint feels the “stretch” sensation. This stretch is then held for 20 to 30 seconds or longer. Static stretching has been part of many warm up routines but more recent research has cast doubt on its benefits and in some studies has shown that it may increase the risk of injury or contribute to poorer performance when done prior to activity or competition. This is not to say that static stretching has no part to play in training and competing as it has been shown to increase range of motion. Range of motion (ROM) is important for a number of reasons not least being that the better our range of motion the further we can reach to complete a movement or technique. The other important factor is the power we can generate if we have a greater ROM. A good analogy for this is an elastic band when we stretch it and fire it across a room; if the band is shortened in any way the distance of travel is less, less power is generated. Our muscles are just living elastic bands and if they are shortened they will not produce their maximum potential. There was an excellent article reviewing much of the research on stretching, including references to some of the risks of static stretching published in the International Journal of Sports Physical Therapy and can be found at http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3273886/ Based on the effectiveness of static stretching in increasing ROM I would always recommend a static stretching session post exercise. At the very least a static stretching session post exercise allows the muscles we have been using to “re-set” to their “normal” length and should help to increase the base line ROM giving further improvement in future performance.
ConclusionThere is sufficient evidence in the research papers to support the implementation of a rigorous warm up and a dynamic stretching routine prior to any exercise. The research also supports the use of static stretching as a method to increase range of motion but highlights that these static stretching exercises should not be used prior to exercise or competition due to the possible loss of strength.
References1. http://www.ncbi.nlm.nih.gov/pubmed/3849057?dopt=Abstract 2. British Medical Journal – Comprehensive warm-up programme to prevent injuries in young female footballers: cluster randomised controlled trial by Torbjørn Soligard et al 3. FIFA’s 11+ warm-up protocol can be found at: http://f-marc.com/11plus/11plus/ 4. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3273886/ 5. Medicine ACoS ACSM’s guidelines for exercise testing and prescription. 7th ed. Baltimore: Lippincot Williams Wilkins; 2006
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