Posts tagged “race

Physics of Acceleration

Acceleration = (final velocity – initial velocity) / (time at finish – time at start)

Basically, the more you change your speed in a shorter amount of time, the more you have accelerated.  Having a race start that features high acceleration is often a strong deciding factor in races of shorter distance and where the average speed of boats are closely matched.  With the 2017 CDBA Sprint Races just having finished this past weekend, it’s time for teams to start working the long game in prep for more 500m racing fun this summer.

What I wanted to write about regarding acceleration in race starts is to address the wide variation in how teams fiddle with stroke counts and stroke technique in hopes of finding an edge over their competitors.

Many coaches I’ve spoken with over the years often have one of two philosophies about race starts: don’t fix what isn’t broken OR try something different.  The leave-it-be coaches may have strong personal histories of success utilizing a certain race start count and stroke style to the point where the idea of trying something new seems like it would hurt more than help team performance.  That fear is completely understandable, and in certain cases, may be quite accurate.  Think of the novice team trying dragon boat for their first race.  The ‘ole 5-10-10 presents both a great mental and physical challenge with plenty of clacking paddles and drenched partners.  Chances are that coaching different rate ratios and stroke techniques would probably be lost upon such a crew because performance is being limited by base skill.  Now, take the elite paddling crew; each paddler with multiple years of racing experience and a high level of fitness.  If we’re referring to a tight-knit crew with at most 1-2 new additions vs a thrown-together “dream team,” tweaking the start might also be a waste of time because the crew has perfected their start and any change is, again, probably a waste of time.

So why chase new and different race starts at all?  My answer is: because no crew is the same as the next.

Getting back to acceleration, the basic philosophy of a race start is to get from dead stop at the starting line to race pace as quickly as possible.  I’ll ignore “as efficiently as possible” because when it comes to 500m or less, who cares who did it the cleanest if they lost to a team with a “messy” start?  If efficiency was poor in the faster team, it just means that team could have accelerated faster next time.  To me, a winning start is plenty efficient no matter how it looks.  Think of how noisy, messy, and almost out of control a drag race car start is compared to driving around your Prius.  The dragster was efficient at accelerating like a beast while the Prius was efficient at saving fuel and not waking the neighbors.  The dragster wins.  Be the dragster.

But how do you know if a start is giving efficient acceleration?  Well, you could test like I used to with a GPS and stopwatch or utilize buoys of known distance.  Find your team’s sustainable race pace and seek to get to that speed ASAP.  There’s the chance for playing around with ratios and technique.  The goal is to eliminate dead-spots in acceleration on the way to full race pace.  The other goal is NOT to completely overshoot race pace and exhaust the crew before you get past the 100m mark (unless 100m is the race).

On to ratios and technique, faster acceleration demands a greater amount of power.  Power is the rate at which work is done.  Each paddle stroke does some work.  Stroke too long and slowly and power is lost.  Rate up too quickly and shorten the stroke, power is also lost.  The sweet spot for every team lies in the middle somewhere.  Physically stronger, more explosive teams can afford to rate up faster because they can put out more power.  Weaker teams may benefit from an intentionally more gradual workup.

Once the start is over, the time to accelerate is done.  Some teams opt for a high stroke rate during the race because it seems “faster.” (as in people moving their bodies/paddles quickly must be making the boat move faster, right?)  Well, again it depends on how the team can physically maintain their chosen race velocity.  If the team can ONLY generate adequate power to sustain that chosen speed, then sure, thrash away.  Their hearts will probably be running a few extra beats/min higher than a team that is able to maintain the same boat speed but at a lower stroke rate.  If you have a paddling erg, you can see how your heart rate changes if you decrease the paddle resistance and hold a higher stroke rate during a time trial vs a slightly heavier pull but lower stroke rate over the same distance.

Case in point, you can see how DW drops the stroke rate but maintains their boat speed while other adjacent teams maintain high stroke rate without gaining ground:

Compare that to our video from the 2009 Sprint Race where SFL was doing dry starts with rather meek acceleration between strokes 0-2.  I definitely do not think the strongest SFL team of its day could stand up to the crews of today, mostly based on the average physical fitness of modern, A-div teams.

I’m still proud to say that I was able to coach a crew of highly dedicated and passionate paddlers of a wide variety of fitness levels and skill into becoming a consistent contender for A-div podiums over the course of several seasons.  Thanks for the memories, everybody!


Finish It…Slowly?

How much paddling effort is optimal for different parts of the race?  Certainly very few if any athletes can go 100% effort for 2 continuous minutes without fatigue affecting performance, so for a 500 meter race, it behooves the athlete and coach to know how effort can best be used to pace the race in order to get the best time.

Physiology review!

Our muscles contain several different types of fibers, each with their own attributes that allow us a range of force-exerting capabilities from holding a baby kitten to performing a heavy dead lift.  Motor control is a complex system within the brain but outside the spinal cord, things get simpler.  This is what we can focus on for the scope of this post.  Motor neurons of different sizes connect like wires to muscle fibers, stimulating them to twitch and eventually reach sustained contraction, or tetanus, with enough action potentials/electrical signal.

We can group motor neurons into 2 main groups, large and small.  Likewise muscle fibers can be grouped into 2 main types, Type I and Type IIa/IIx.  Small motor neurons recruit Type I muscle fibers, which are slow to contract, produce low force, but are very fatigue resistant.  Think of the muscles that operate your eyelids.  Unless you’re the average college student, those things stay open most of the day and possibly through late nights in places your mother shouldn’t know about.  Similar muscle fibers operate even when you are walking.  Most healthy individuals can walk and talk with minimal fatigue.

Large motor neurons carry fast electrical signals to your so-called “fast-twitch” muscle fibers.  These fibers take relatively more signal to contract, but once they do, they produce high amounts of force in a short period of time.  They also fatigue quickly.  Going from a walk to a sprint or performing a box jump will fire these Type II muscle fibers.

Muscle Fibers in Paddling

Paddling is a mix of muscle fiber utilization, as many daily activities are as well.  The start of the race is strenuous because the boat is at a standstill and the water feels very thick/heavy.  Taking hard strokes through this situation will favor the Type II fibers.  As the boat reaches race pace and the speed plateaus, less emphasis on power per stroke (and thus less fatigue per stroke) can be applied to simply maintain race pace and hull speed vs accelerate the boat.  Have you ever been on a boat where the crew hits an overrate and keeps it there?  I have (a few times) and it doesn’t end well.  Rating down and reducing power per stroke results in a lower reliance upon Type II fibers for paddling and less fatigue.

Some teams may call powers or some equivalent bump in effort to strategically stay ahead of other racers or simply to fight a gradual decline in hull speed.  Again, taking harder or faster strokes will result in more Type II fibers being recruited, which will contribute to fatigue.

For the finish, is it better to pull a hard and fast acceleration or a gradual one?  It depends.  Highly trained athletes with good conditioning will have a better ability to recruit Type II fibers with less fatigue, but you can’t fight the physiology of trying hard.  Fatigue will hit and sap the performance of any and all who exert 100% effort.  No team wants to be slowing down by the end of the race, after all.  In this sense, a hard and fast finish will mean an athlete can exert themselves for a shorter amount of time before bonking out.

Don’t Bonk!

Don’t Bonk!

Assuming that your boat is dead-even with the competition, travelling at the same speed, and the other crew maintains the same speed through the finish line, your crew will need to accelerate to pass the other boat.  This is where a “finish” is useful in the most basic sense.

Acceleration requires the application of more force and power to the water.  This power ramp can be applied gradually over a period of time or more aggressively in a compressed time frame.  It obviously takes more energy to accelerate quickly and it is relatively more difficult to accelerate a moving boat than it is a stopped one (really!).

A crew that takes a more gradual approach to the finish may reduce the fatigue associated with accelerating the boat but will need to avoid making the finish so long that fatigue causes hull speed to drop before the finish line.  The competition also poses a variable for when and how to run a finish.  Calling the finish after that of other nearby crews potentially demands your boat to accelerate in a shorter amount of time to avoid being passed.  Being “forced” to finish on account of another teams potentially better race piece may result in excess fatigue for your crew and decreased performance.

Most coaches recommend racing your own race, which has plenty of wisdom to it, however when up against close competition the ability to adapt on the fly is very useful when winning is all that matters.


Putting Your Best Leg Forward

The debate rages on (not exactly raging, but it happens) as to what foot position is best for dragon boat paddling.  Some argue the inside leg should be forward, while others state the outside leg forward works best.  Others argue for both feet forward.  Ultimately, I agree with Steve Giles when he writes “get comfortable, keep the weight moving forward, put your feet wherever you want.”

Inside vs Outside Leg Forward

It’s the commonly accepted technique used by C1, C2, and C4 paddlers, so ’nuff said?

DB paddlers with inside leg forward

C1 canoe racing

My thoughts are that the inside leg forward is not easily transferable from canoe racing to dragon boat.  Not having any experience in C1, C2, or C4, I am speculating that putting the opposite leg forward in the canoe helps maintain balance in the boat during the pull.  The canoe is very narrow and does not appear to have very much lateral stability (certainly compared to a dragon boat where you can stand edge to edge and the boat won’t flip).  As I wrote here, paddling exerts a downward force on the boat, but what I didn’t write about initially is that it does depend on where that force is transferred to the boat.  In the case of the C1 canoe, the force exerted on the paddle is transferred to the boat primarily by the forward leg.  When the forward leg is opposite the paddle, it applies equal downforce across the boat midline, preventing an immediate tip-over.  The other aspect of the foot position is related to the half-kneel position of the C1 racer.  You can see in the pic that the paddler can swing their pelvis away from the paddle during the stroke to likely get more power, better balance, and more stroke length.   If anybody has canoe racing XP, please feel free to clarify if my thoughts are accurate.

In a dragon boat, if a pro paddler like Steve Giles felt uncomfortable with this position is that enough reason to avoid it?  My thoughts are that placing the inside leg forward makes your leg drive come from the inside.  If a large portion of stroke power comes from rotation/de-rotation, pushing with your inside leg during the pull phase will tend to push your inside hip back, rotating your pelvis to the INSIDE of the boat.  If you think about it, this is the opposite direction that you want to rotate during the pull phase.

Additionally, leg drive with the inside foot alone makes the paddler work against more torque, giving a mechanical disadvantage and robbing efficiency.  If you took a top-down view the paddle is pulling water a certain distance outside the boat, creating a torque moment.  The axis of rotation is the paddler’s outside ischial tuberosity (butt cheek).  Leg drive with the inside leg creates a torque moment that is farther away from the outside butt cheek, making the paddler work harder to transfer force to the boat.

Another potential reason the inside leg forward is not well applied to DB because the bench prevents the paddler from swinging the pelvis back during leg drive as is possible with kneeling in canoe racing.

No “best” foot forward?  Why not both forward?

Certainly another popular foot position to use in DB is both feet forward, similar to OC racing.  With larger OC craft being quite similar to DB in terms of paddler position relative to the water, I’d say the technique works better than the inside leg forward.  Folks have claimed that leg drive with both legs is stronger than one foot forward, but really?  Your trunk and upper body will always be much weaker than just one of your legs.  IMO, the main limitation to power in paddling is from core strength/stability than leg strength.  You are only as strong as your weakest link.

Both feet forward may reduce the paddler’s ability to rotate on the reach because it tends to lock the pelvis down both in terms of hamstring flexibility and ability to swivel.  If a paddler is able to put relatively more weight over their outside ischial tuberosity and unweight the inside leg slightly during reach, it may make a well-balance stroke….but if you’re already un-weighting the inside leg to get a good pull, why not just put the outside leg forward?