Swim Fins
Fins are great training tools. When used properly they can improve both technique and strength. They are generally composed of rubber or polyurethane and are offered in multiple sizes. Normal-size fins have a blade about the length of your foot while short training fins have a blade length 1-2 inches. Normal-size fins are better suited to teach the undulation necessary for butterfly and to reinforce the breaststroke kick. Short fins are suited for freestyle and backstroke because they permit a normal kicking rhythm.
Using fins has many effects. They
obviously enable one to swim much faster and emphasize the need to be
hydro-dynamic ( slippery in the water). The greater propulsion also keeps
the body up in the water, improving balance. Fins can also serve to focus
the kicking motion correctly
from the hips rather than from the knees, and in many, awaken the dormant upbeat
portion of the kick rather than relying solely on the downbeat. Consistent
use of fins will increase foot flexibility over time which abets a better kick
as well.
If you are incorporating fins into your swim regimen for the first time, treat
them like any other change, let your body slowly adapt. Avoid cramps and
injury the additional stress can create by easing them into the workout and
building up as you become more and more acclimated.