Groin Kick syndrome: Part II

Kick Konfusion

Over the weekend many athlete's tightened up at the end of their races. Tightening up or groin kick syndrome is a multi-factorial result, but one potential mechanism was discussed last week with groin kick syndrome: part I. In order to improve this facet in your swimmers it is essential to understand the chain of events and give a method for improvement. Unlike many circumstances where one variable is the cause, GKS is multi-variable and halting events at the beginning of the chain will improve the subsequent variables.

Many coaches default GKS as purely a conditioning flaw or even worse a gauge an athlete's toughness. These two reasons do occur, but are not always the result. Looking for solutions is essential and relying on a $300 suit isn't the answer, as minimal differences were noted in Austin, TX with the new tech suits. I do not think these suits will make a noticeable change in times, but it will be hard to gauge. For example, if a swimmer improves 0.1 in a 10o free, was it secondary to the suit or training? This is a tough decision someone must make when you have a 13-year old girl spending $700 on a suit! 

I feel the goggles are the only vast improvement, not sure how much but I'm intrigued yet disappointed it took this long for goggles to transition towards cyclist helmets considering more drag occurs in water than air. Then again, they are going higher speeds and their head is the first object to pave the way in new air, typically (hopefully) the arms are breaking new water and the head isn't leading the way.

Back to GKS, leg spin is the first step in the GKS continuum. Improving leg spin and distance per kick is the most influencial aspect for improvement with distance per kick. If this aspect improves, the rest of the continuum will follow suit. The best method to improve leg spin is to improve distance per kick (DPK). This unfamiliar topic is like distance per stroke, but measures kicking efficiency. From my experience, many coaches and learn to swim instructors are unfamiliar with the biomechanical movement of a kick. Unfortunately, no concrete evidence (that I've seen) has measured the kinematics of freestyle kicking, but underwater video can do wonders!

Kicking biomechanical confusion

"Keep your knees straight! Kick from your hips!"

These two phrases are constantly screamed at little kids on the pool deck. Unfortunately, straight knees are far from the reality in elite swimmers. Great swimmers typically do 60-80 knee flexion to propel themself forward with a rapid knee extension. I'm not suggesting initiating from the hip isn't important, but in reality swimmers use approximately 1/3 the amount of hip extension compared to knee flexion.

In the Club it's going down...kick

Flutter kicking is a whipping motion starting from the hip. First the core must stabilize to prevent excessive frontal and transverse movement, then the hip must begin to flex (for a downkick), then the knee extends and the ankle points (plantarflexes). This whip motion generates more force than kicking with straight legs like toothpicks. This downkick is the most propulsive movement in kicking and teaching swimmers to only kick from the hips takes out the most power muscles in the downkick the rectus femoris (RF). The RF is the only muscle which flexes the hip and extends the hip, having proper timing and use is essential to prevent step 2 in GKS, No Ro.

No Ro is the result of fatigue causing poor muscle timing. Studies on soccer players (Apriantono 2006) found a decrease in kicking velocity was due to poor kick coordination, they stated:

"slower peak lower leg angular velocity, was most likely due to a significantly reduced resultant joint moment and motion-dependent interactive moment during kicking. These results suggest that the specific muscle fatigue induced in the present study not only diminished the ability to generate force, but also disturbed the effective action of the interactive moment leading to poorer inter-segmental coordination during kicking. Moreover, fatigue obscured the eccentric action of the knee flexors immediately before ball impact. This might increase the susceptibility to injury."

Soccer kicking isn't identical to swimming kicking, as more hip extension is utilized in soccer, but the same process and muscles involved (in my opinion) results in many similarities. 

Upkicking Ain't Easy Baby

A lot of coaches stress the upkick, feeling it propels the body forward. In my opinion, the upkick is less about propulsion, but more for balance and rhythm. If you only kick one way, your body can't perform the subsequent phase properly. For example, if you don't do a correct or full upkick, then your downkick won't be in the right starting position. These two phases need seamless transitions and if your body is stick downkicking, then you'll never achieve a whip kick. The upkick sequence starts with hip extension, then knee flexion and slight ankle dorsiflexion.

It is clear to see the end of the upkick is the beginning of the downkick. Finishing each phase fully sets up the body or the next kick by providing balance and rhythm.

Wrap-up

Next week I will discuss methods to improve the whip like motion of the downkick, forcing a rhythmic upkick and methods to measure and practice distance per kick (DPK).

By Dr. G. John Mullen, DPT, CSCS. He is the founder of the Center of Optimal Restoration and head strength coach at Santa Clara Swim Club.