Aaah , swimming. The liberating feeling of weightlessness, the exhilarating cool water, the streamlined motion through an alien, pre-birth element. What could be more enjoyable?
But wait, swimming was not always viewed so positively. In the 16th century, a vice-chancellor at Cambridge forbade it. Penalties for disobedience by undergraduates included public flogging, a 10 shilling fine and being placed in the stocks. Eventually, one of his Dons resisted. In The Art of Swimming, he promoted swimming as a great help in the extremity of death and a thing necessary for every man to use; especially to purge the skin of all external pollutions and uncleanliness. In time the doctors came around. Sterile men and women were advised to take up swimming. It was believed to restore color to the wan cheeks of consumptive young ladies, to regulate menstrual periods and calm their neurotic temperaments. It was recommended for glandular and venereal diseases, rheumatism, to sooth painful corns and bunions, and even some forms of insanity. It was believed helpful for restoring the constitutions of the dissipated man about town, refreshing the overworked and enlivening the pallid. It was supposed to straighten the legs of rickety children and reform the unwholesome thoughts of young people.
One of the aforementioned problems not yours? Painful corns? Unwholesome thoughts? Ah well, let's see. Cramping. At one time the horror of it was so great that a short walk following lunch was a feared thing. And swimming, well, we had to wait 2 hours after lunch before immersion to prevent catastrophic consequences.
However, muscle cramps; spasmodic, painful, involuntary contractions are a different animal. Medically, statins are high on the list of possible causes. Though they can be lifesaving medications, Zocor, Crestor and Lipitor are myotoxic. Low potassium (which may be caused by diuretics) and abnormal electolytes are also suspects. Though you feel you consume enough potassium, there are the appropriate blood tests. Doppler studies to rule out peripheral vascular disease and an appropriate neurological workup may also be considered. It is believed that there is an element in coffee beans (not caffeine) that may cause cramping. If you consume coffee on a daily basis, try going without for a while.
Biomechanically, the feeling of your toes crossing over is caused by cramping of either the intrinsic foot muscles or the posterior leg muscles. Try to alleviate tightness with gentle gastoc-soleus stretching exercises. I like the 'wall-leaning' ones as opposed to the 'stepping off the curb' ones because there's a better element of control. And no bouncing. Stretch at night and in the AM. Stretching may work for you soon after training; some find it easier to wait several hours.
Fatigue may lead to abnormalities in the mechanisms that control muscle contraction. Changes occur in muscles that contract in a shortened position for extensive periods of time. During prolonged exercise, it is believed that the inverse stretch reflex that inhibits excessive muscle contraction becomes inactive due to reduced sensory input. Also, stimulatory impulses from the spinal cord to the muscles increase, which may increase the possibility of cramping (the Schwellnus theory of muscle cramping).
Concentrate on relaxing the lower leg during swimming, as well as biking and running. During swimming, focus on complete relaxation from the hip down. Don't overuse those calves! We get enough leg work/tightening during biking and running. Just let your legs trail or kick as a slow stabilizer to your hip rotation. Hold up on any kickboard work.
Sneakers or shoes a tiny bit tight in the forefoot? This can result in cramping of the toes hours after removing them. If the heel is too soft and squishy, a quality of many running shoes and some comfortable dress shoes, this can overwork the leg and intrinsic muscles. If you have a flexible foot type, these shoes are not for you. A more rigid, or stabilizing shoe may work for you. A prescription orthotic device is a big help for this foot type. Infrared therapy or light massage may also help.
This type of cramping usually diminishes over time. Focusing on relaxation, stretching, appropriate foot gear and consider a biomechanical exam.