Three ways to better the kick.
Triathletes tend to suffer from a triad of limitations when developing a good kick, but they can be overcome with proper training.
The first is ankle flexibility, and triathletes with significant running backgrounds tend to have the least flexible ankles. Swimming with long blade fins tends to increase ankle flexibility and gets the athlete in the proper body position to coordinate the kick and pull. Also, the extra speed from the fins encourages the athlete to engage the core while swimming. For extreme lack of flexibility, some athletes will require dry land stretches like sitting on ankles.
Second, time spent running and in the saddle creates tight hip flexors, pulling the hips underneath the body when in the water. Again, using fins and a kick board while focusing on a long, flat body position in the water will help overcome this imbalance.
Third, many triathletes tend to kick from the knee, but the kick should originate in the hips. While kicking, the leg should be relatively straight with the knee and ankle relaxed to allow for the efficient transfer of energy to the foot. Think of the kick acting like a whip, with all of the power being focused at the end. The amplitude of the kick should be narrow--in other words, the arc of the foot shouldn't go too far out of the water or too deep.
Here are some sample kick sets to insert after a warm-up and before a main set:
Kick Set #1
6-10 x 100 kick with fins (1 fast / 1 easy) @ 2:00 (Adjust interval and repeats depending on ability level. Swimmer will need a little more rest than a usual swim set.)
600-1000
Kick Set #2
12-16 x 25 kick no fins (3 fast / 1 easy) @ :40 - :55. (Adjust interval and repeats depending on ability level.)
300-400
Kick Set #3
10 x 30 seconds fast kick against the wall; 45 seconds rest. (If you are struggling with kicking, use the wall to get your body flatter on the water and better control the kick amplitude.)
Tim Floyd, swim coach and former NCAA Div I swimmer, founded Magnolia Masters in 2010 to specifically help triathletes improve in pool competitions and open water swimming. Magnolia Masters is committed to providing the best training and swim technique analysis to help each athlete achieve their best results in the swim. You can find more information about Magnolia Masters here.