Why do I get cramp when exercising?

School Of Pilates Posted Apr 29, 2014 Future Fit Training


Cramp is a common occurrence within Pilates and there is often no real reason why it occurs. So what exactly is cramp? Cramp is a sudden involuntary contraction of a muscle that can occur in the thigh, calf or foot. If the cramp does not reside with any known medical condition then it is known as an ‘idiopathic cramp'.

Why do I get cramp when exercising?

Let’s look at the physiology highlights of how these cramps can occur. A muscle is made up of many muscles fibres and within them are sub units called myofibrils (actin and myosin myofilaments). These allow nerve impulses to be transmitted throughout the myofibril.  The sarcoplasmic reticulum is also found within a muscle fibre and acts as a storage site for calcium, which is essential for muscle contraction.

When a muscle is stimulated to contract, the sarcoplasmic reticulum releases calcium causing actin filaments to bind with the myosin filament. The head of the myosin filament contains a connecting site for ATP (adenosine triphosphate) which is the energy supplied for muscle contraction to occur. The energy created by the breakdown of ATP is used to connect the myosin filament head to the actin filament.  The connection between the myosin and actin filaments bind creates a strong bond to form cross bridges.  This is known as the sliding filament theory and it’s where the actin and myosin filaments are drawn in opposite directions and results in the muscle shortening.

As previously mentioned, calcium is released and this plays an important role in the action of nerve impulse.  If calcium is not inhibited then the nerves keep firing impulses. This continuous activity results in an increase of carbon dioxide and therefore a lack of oxygen which inhibits the body’s ability to produce ATP.  If there is a lack of ATP then the myosin filaments can’t disconnect from the actin filaments and prevent the muscle returning to a relaxed state, hence we gain a cramping feeling.

There are a few ways that we can help our clients but if they continue to complain of leg cramps it would definitely be a good idea to advise them to seek medical attention to rule out any underlying health conditions that could be causing it.

Our clients may get cramp in Pilates if they try to point their feet too hard or curl their toes under, making the muscles in the leg overactive. Advise them not to planterflex their feet too much and maintain a relaxed foot position. Think of the leg as extending and lengthening than the lower legs and feet having to do all the work. 

Stretching the affected area is a good option so if cramp occurs in the calf or foot, dorsiflex the foot and also massage the affected area.  The other option is to walk around on the heels for a while until it eases.

Try doing more foot work in your Pilates sessions.  Use a small golf ball to roll out the fascia on the sole of the feet to increase circulation and blood flow.  This can be a nice treat for your participants and circle the ankles frequently within the class.

Encourage participants to hydrate frequently throughout the day and maintain a healthy balanced diet rich in magnesium - dark leafy greens, nuts, seeds and potassium. Try eating a banana before a Pilates class as this will help to make the required ATP and prevent the cramping feeling.  

Article written by Lizzie Tuff

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