Kicking mistakes in backstroke

The mistakes that swimmers make most often are to (1) pedal the legs and (2) kick too deep. In addition, swimmers who lack ankle flexibility will not be fast kickers.

1. Swimmers who tend to pedal the legs usually lift the thighs too much during the upbeat of the flutter kick and they extend the legs by pushing them forward, rather than extending them upward, in the manner of pedaling a bicycle. When the knees rise above the surface of the water during the kick, you can be sure that backstrokers are pedaling rather than kicking the legs. The primary problem is that they push the thighs upward and forward against the water during the upbeat and this produces pushing drag that slows forward speed. Swimmers should be instructed to keep the knees underwater and to straighten the legs completely on the upbeats of the backstroke flutter kick.
2. Two things can happen when the kick is excessively deep, both of which reduce forward speed. The first of these detrimental effects will be an increase of form drag, which occurs because the cross sectional area taken by the body will increase due to the depth of the legs. The proper depth for the kick is approximately 45 cm. The second effect is that the hips and trunk will be pushed up if the thighs push down below the body during the downbeat, which will disrupt horizontal alignment  and reduce forward velocity. The thighs should not travel down below the hips during a downbeat. The lower leg may drop below the body when swimmers flex the hip during the upbeat, but this is not a stroke defect.

Swimmers who kick too deep tend to kick by simply extending and flexing the leg at the knee with little or no involvement of the thigh and hip. The most serious problem is that they generally flex the leg during the downbeat and, in so doing, push the lower leg forward against the water. The legs should be kept straight on a downbeat, and they should not bend until the pressure of the water forces them into a flexed position during the first portion of the next upbeat.

FYI: A few days ago Beu, an online magazine for women, posted my article ''Purposes of goal setting'' and that made me very happy because it shows that this blog is really good. 

Image source [1]