The dancer in training Strength

Learning outcomes By the end of the lesson: Students will understand how to increase strength. Learn major muscles and their function in dance. Recognise dance injuries.

What is strength? Strength is the capacity to exert a muscle contraction against resistance. Contraction is the opposite muscle action to that of stretching. A strong body moves freely, efficiently and above all safely. The aim is all-round strength, not the over development of certain muscle groups.

Types of strength During exercise, there are two types of strength:  Isotonic  Isometric

Isotonic This involves a dynamic resistance during which the muscle changes in length. Isotonic work may be either; Concentric – muscle shortens to produce a movement e.g. hip abductors of the gesturing leg as it is raised to the side Eccentric – muscle lengthens with tension to allow movement e.g. hip abductors of the gesturing leg to control lowering it to the ground Exercises may be performed, in the full range of motion of a joint, in sets of 10 to 15. Reps slowly build to 2 or 3 sets.

Isometric This involves static resistance during which the muscle tension increases but does not shorten e.g pushing against a wall or in dance terms; when a leg is raised to the side, holding it there means that the hip abductors have an isometric contraction to resist gravity.

Generally to increase the strength of a muscle, it must be overloaded. The dancer strives for an increase in strength and co-ordination by perfecting class exercises thereby improving general technique and developing speed.

We can overload muscles to build strength this involves changing: Frequency: increase the number of repetitions or speed of a movement. Intensity: adding more and more resistance, as with weights. Duration: increasing the length of time a movement takes. For example: holding a leg off the floor against the pull of gravity, will build up strength and stamina in the quadriceps. With added progressive overload the muscle size and strength will increase.

Muscles Muscles are the ‘meaty’ part of the body. In dance, it is the skeletal muscle that is of concern. Muscles are attached by tendons to the bone at each end (a) the end of the origin – this stays still; (b) the insertion – the end which pulls and moves.

The quality of the physical condition of the muscle depends on 5 factors. Tone or degree of firmness Freedom from fatigue Store of readily available nutrients Temperature Ability to recover from work Training influences each of these factors.

Muscle development is associated with size, strength and endurance. Increase in strength is measured by an increase in the power of contraction. Endurance in a muscle means its ability to delay the onset of fatigue and the efficiency of respiratory and circulatory systems greatly assists the muscles ability to endure work. Another factor which increases the effectiveness of trained muscles is better neuromuscular co-ordination, an increased skill in movement with elimination of unnecessary muscle work. This co-ordination is developed through persistent training and practice.

So how do we move? Muscles can only pull (ie contract), and movement is brought about by pulling on the bone so as to turn these bones into levers. The structure of each such lever has 3 main parts: The load or weight The Fulcrum (balance point) of the joint The muscle action producing the effort at the point of the muscle insertion.

Types of lever There are 3 types of lever First order Second order Third order

Third order lever

Which is the most common? The most common is the third order lever. The ‘effort’ moves a shorter distance than the ‘load’. This has the advantage of allowing a large movement to be made with only a slight contraction/shortening of the muscle, thus making it a more efficient movement.

Muscle contractions Contraction occurs when muscle fibres shorten and movement is produced. This is concentric contraction (as in contraction of the biceps). Muscles also produce eccentric contraction – to straighten the elbow the biceps brachii muscle fibres will lengthen.

How do they work in dance? A plie begins with the pull of gravity, as controlled by an eccentric contraction of the quadriceps. Then when the quads and hip extensors contract concentrically, the body is raised against gravity back to standing.

Anatgonists To dance without injury, a muscle needs a high level of efficiency in the antagonistic action of its pair muscle. This means that while a muscle is contracting, its opposite muscle must relax smoothly.

Muscle pairs Biceps (front upper arm) and triceps (back upper arm) Rectus abdominis (front torso) and the long muscles of the back Tibialis anterior (front lower leg) and gastrocnemius, soleus (back lower leg) Thigh adductors (inside thigh) and gluteus medius and others (outside thigh) Quadriceps and hamstrings

Injuries – muscles and tendons The stronger the dancer the less the risk of injury, e.g. stronger hamstrings may reduce the risk of lower back injuries.

Injuries to muscles and tendons Both muscles and tendons are liable to injury. If a tendon is irritated by overuse, tendonitis may occur (usually in the achilles in dancers). Muscles are usually injured by a sudden movement or weak muscles from poor technique or overuse.

Achilles tendonitis The symptoms are tenderness and crunching, particularly when plantar flexing the ankle. Careful stretching of the soleus and gastrocnemius when cooling down reduces the likelihood of tendonitis.

Vulnerable muscles to a dancer The groin (iliopsoas, rectus femoris, adductors) The hamstring group The gastrocnemius A thorough warm up will help reduce muscle and tendon strains, as it will for joint sprains. If you do injure yourself, the following is a good guide!

How to cure an injury? R I C E