Last Updated on March 14, 2013 by Jimson Lee
This is Part 6 of the weekly “Friday Five” series where I ask 5 tough questions to world class elite coaches. Week 1 was with renowned jumps coach Boo Schexnayder and Week 2 had Dr. Mike Stone of the USOC and NBA. Week 3 was performance specialist Henk Kraaijenhof and Week 4 had Dan Pfaff. Week 5 has Pierre-Jean Vazel of the French National Team.
Dave Kerin’s time as USATF Chair for Men’s & Women’s High Jump has coincided with a resurgence in the event. The last 2 years have brought 2 new American Records and a World Championship with Chaunte Lowe & Jesse Williams among USA’s medal favorites for this summer’s London Olympics. Dave’s coaching career began with 14 years at the HS level followed by 14 years of collegiate coaching where an athlete set still standing NCAA D III records in WHJ. A requested speaker and published author, he is perhaps best known for his work: “What is the most direct means to achieve strength gains specific to the demands of jumping events”. He also presented that topic at the 2008 USATF SuperClinic (click here for that PDF)
The paper was the first to propose and defend the primacy of Eccentric-specific training over traditional methods of the day. A more recent project has been work on a new analysis model and performance review format for the country’s elite jumpers in partnership with USATF Biomechanist, Jim Becker of the University of Oregon. Retired from college coaching, Dave continues to be a coaching education instructor and a resource in correspondence with collegiate and HS coaches across the US & Internationally.
Friday Five is sponsored by Freelap Track and Field, a leader in electronic timing.
Interview with Dave Kerin
Q1 – SpeedEndurance.com: Would you share some of the underlying demands of the high jump from a physics perspective? Would you also clarify the biomechanics involved so it’s simple enough to remember but not so dumbed down to the point it’s just dumb?
Dave Kerin: Parabola & Vertical Velocity at takeoff are the result of Posture & Horizontal Velocity at plant. A paradox is the need to impart the greatest force, over the greatest Range of Motion… over the least amount of time at plant. A so called “Speed Jumper” would favor “least amount of time”, with a “Power Jumper” trending to the ROM side of the paradox. The requirement to not dislodge the bar finds some raise their Center of Mass highest, yet do not win. This is where the suggestion that an NBA high flyer would easily transition to world class high jump, fails. Once the jumper leaves the ground, the COM is essentially a projectile traveling a parabolic curve. The chord or base of the parabola needs greater length across the ground to facilitate higher bar clearances. With parabola determined, optimal bar clearance would find the COM as low as possible via arching. Other keys: Overcoming inertia in the first approach steps. Transition from the linear to the curvilinear & running a true radius are dependent on closing the angle at the ankle nearer to fully grounding of the foot as opposed to “toeing down”. Avoid a return to acceleration mechanics (uprighting) in the curve. Body lean in the curve occurs at the ankle and is the result of horizontal and vertical forces. Execute the penultimate step with minimal loss of leans and velocity. Often forgotten, a second lean is observed where the hips lead shoulders into the plant. Double arms to block at takeoff can contribute to force but to my view, too much horizontal velocity is lost by too many when setting up for the double arm action.
Q2 – SpeedEndurance.com: Many events have benchmarks such as 30m fly, medicine ball throw, standing triple jump, and other tests to see how the athlete is developing. The High Jump seems to not have much by way of physical preparation standards as many coaches see it as a talent identification instead of a talent development event. Could you share how training and not just technique work, is important to getting athletes physically able to perform higher?
Dave Kerin: Actually there are benchmarks from elite athlete testing results and any coach who tests and keeps records has the same resource specific to their level of competition. One example would be OHB’s and if you think about it, the OHB has an event rehearsal relationship with HJ. They also have value as CNS arousers and can measure power drop off. Lack of quality & harmony of the Biomotor skills is almost always the short fall so start there. For the HS coach, remember you can hold your breath and HJ so aerobic work is not a prized resource. Most who attempt the event are able to generate horizontal velocity equal to the task. But can they run the curve and are they strong enough at the plant to amortize? The subject of Tendon enhancement is a current topic worthy of research.
SIDENOTE: Schmidtbleicher’s "reactive strength” test
He compares squat jump performance, with drop jumps from heights of 16, 24, 32, 40 and 48 cm; possibly up to 56 cm, depending on qualification level.
A novice athlete’s best drop jump performance may be 20-25% below his/her squat jump, indicating large reactive resources. This can be interpreted as a functional deficit in one’s short-response SSC abilities, with the subsequent need to emphasize reactive movements (such as drop jumps, vertical jumps or countermovement jumps) in training.
In contrast, an elite athlete’s drop jump result may be up to 20-25% greater than his/her squat jump, indicating small reactive resources. In this case, basic strength should be emphasized through hypertrophic and/or neural adaptations in order to create "new" reactive resources. (Hence my – “How bout raising their 100th percentile to raise the 30-60th”)
UPDATE: see the 8 minute video at the comments section below (at the end of the article)
Q3 – SpeedEndurance.com: The event is asymmetrical in nature, making it risky to athletes not prepared properly. Could you talk about single and double leg plyometrics as well as conditioning for the event? I was surprised that you talked about longer sprints and double leg depth jumps in your educational talks. Anything surprising about proper training? Most coaches are comfortable with a few approach jumps and calling it a day.
Dave Kerin: High Jump is a speed and power event. Double leg plyos have their place but timing – plant to ground release is around 2/10ths of a second off a single leg (for an elite jumper) To get away from full approach jumping as conditioning, something needs to approximate event specific demands. Over the years I have shifted to an emphasis on Eccentric strength with said work being dynamic rather than simply “negatives” tacked on to the end of an exercise set. While coaching at the HS level, I liked a Hurdle / HJ event combination for athletes. I believe raising absolute strength is under appreciated and is a “high tide raises all ships” approach to address power output. But then some can do very well on the HJ apron with little time in the weight room as elastic response is not completely weight room dependent. I don’t need to see free weights overhead with my preference being High Pulls as not racking out the bar puts all the focus on constant acceleration of the bar before dropping it. I had someone tell me about bringing a bike to the track and having them pedal into the curve to instruct lean. Another interesting tool shared was using a skateboard to teach “bridging” (getting off the penultimate)
Q4 – SpeedEndurance.com: Would you share some principals of athletic development for high jumpers from middle school to post collegiate? If one was to have theoretically the same coaching philosophy developing the high jumper, how would you see the long term development work? A good long term vision can really help coaches understand their roles and responsibilities.
Dave Kerin: Here you go…
Coach from an Evidence Based – Newton honoring model rather than a Belief Biased model. Make it ok to miss bars during practice, seeing PR height bars preps them for the same when it really matters. Purposeful, planned recovery is crucial for elastic eventers.
There is great disincentive to remediate faults where the jumper is already a Conference or National level scorer. Remediating faults risks a period of performance impairment and as such requires athlete and head coach buy in and altruism from all. More to the point, consider this Randy Huntington quote "If it ain’t broke, break it!"
q=v2/r & r=v2/q r=radius, q = body lean, f=final approach angle, v=speed of approach, p=direction of the center of gravity”
From my response to an elite athlete’s request for their numbers equating to the above formula:
R = you are not running a true radius
F = you enter the plant at too flat an angle, the result of poor curve entry and steps on the curve, along with trying to reaccelerate in the curve & posture loss at penultimate
V = sufficient enough to support your make of X.xx and potentially good enough for X.xx with some fixes needed to fully leverage that velocity
P = your Center of Mass is passing inside of and not over your plant.
The difference between your formula’s question and the review information we gave you after the meet is the difference between a Qualitative and a Quantitative Analysis. Lacking the hard numbers (Quantitative) that we only get at Nationals or the Trials, we address the “Quality” of what we observe…
Q5 – SpeedEndurance.com: Would you list the 10 Commandments for High School Coaches for the High Jump? It could really prevent a lot of mistakes in the future.
Dave Kerin: In the movie, Mel Brooks came down from the mountain with 15, so…
- Don’t take a HS basketball player and erase their existing speed/power/plyo base prior to your spring season. Perhaps think of basketball season as the entrance exam for "AP High Jump"?
- Actual replication the technical model on a rubberized or synthetic apron is near impossible without HJ shoes. The technical model is fatally compromised by sprint spikes, running shoes or basketball shoes. You can’t expect them to do what their equipment won’t enable.
- Using full jumps as the main conditioning modality / jumping every day is analogous to Carpal Tunnel Syndrome.
- Full jumps performed without coach observation is problematic. “Practice makes Permanent” = poor execution becomes the paradigm…
- Stylistic actions most often are in conflict with practical Physics
- Posture affects performance. Most HS kids need constant observation and constant support here.
- Video yourself modeling techniques, postures, et al. You’ll be surprised at the difference between what you are modeling and what you are looking for from them.
- Make it ok to miss…in practice. Many elite jumpers make few bars in practice and max practice clearances can be well below competition PR’s
- Equally, they need to see PR and PR+ bar heights first & repeatedly in practice. When and how often is the art of the game.
- Script and rehearse the periods before the start of competition & between jumps in competition.
- Passing jumps needs to be purposeful and agreed upon in advance rather than in the moment.
- The act of scissoring takes them to a vertical posture well in advance of the plant. Removing the sensation of outward pressure on the foot is the wrong signal to send a HS jumper.
- Too tight a radius doesn’t work, get them beyond adaptation to mastery before any tightening of the curve run. And there is a reason they don’t run the 200m at World Indoors…
- Being from the northeast US, there are indoor tracks who’s lane 1 curve radius is a potential coaching tool, this before a banked track’s potential for enhancing the teaching of curve running.
- Target deep & middle of the pit landings. Such a jump can trace its origins back thru the parabola to optimal plant entry. The lack of more discussion on flight and bar clearance is purposeful as 99% of HS jumpers have multiple, bigger issues to correct first.