Posts tagged “physiology

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.


Want more reach?

Stretch your LEGS!

The hamstring muscles (in the back of the thigh) are a common restriction to getting more effective reach.  Why?  Many paddlers adopt a single leg or double leg forward position in the boat.  This often requires straightening the knee to brace against the forward foot-stop (under the bench in front).  With the hip joint flexed at 90 degrees, this position begins to put tension on the hamstring muscle group.  Since the hamstrings originate from the pelvis, putting them under tension will tether the pelvis to resist what biomechanists call anterior pelvic tilt.  Since the pelvis is the base for your trunk and upper body, having tight hamstrings limits the amount of forward lean at the hip joint with the lumbar spine and pelvis in neutral posture.

What does all that mean?  If you have tight hamstrings (read below), this will limit the amount of reach you have as well as place increased stress on the low back because tight hamstrings will lock down the pelvis and hips, forcing a paddler to flex repeatedly and forcefully through their lumbar spine.

The hamstring’s connected to the…ischial tuberosity…the ischial tuberosity’s part of the…pelvis…the pelvis is connected to the…low back and that’s ana-tomy!

The Role of the Boat

Not all rows in the boat are created equal.  In the BuK models we use in the Bay Area, the gunnel and floor follow a parabolic curvature while the benches stay in-plane with the surface of the water.  What does this mean for a paddler?  The floor slopes down from row 10 to row 5 and then begins to slope upwards from row 5 to row 1.  The floor position (and relative height of the bench post) means that for one paddler to move row to row, there will be decreasing tension on the hamstring during reach from row 10 to row 5 and then increasing tension moving from row 5 to row 1.

The parabolic nature of the gunnel will also affect reach slightly because it will restrict or facilitate rotation, but since a majority of reach (but not necessarily power) is obtained from hip flexion this topic will be explored in another article.

A paddler’s dynamic ability to reach is affected by 3 things: core stability, flexibility, and position in the boat

How much flexibility is needed?

On average, males have tighter hamstrings than do females, regardless of age.  The measurement is typically performed laying flat on the back and passively raising the testing leg with knee straight until stopped by muscle tightness.  Average passive straight leg raise measures for males is 68.5 deg and for females is 76.3 deg (Youdas, et al).  Translated to a dragon boat environment, if a paddler were to sit straight up with excellent posture, one or both legs kept straight in front of them, men could only bend forward 68.5 deg while women can lean forward 76.3 deg before being stopped by hamstring tightness.  To think of it another way, few adults can (naturally) sit on one bench with their feet propped on the next bench up and hold an upright body position at 90 deg (like an L) due to hamstring tension.

Keep in mind that this measurement is performed with the knee fully straight.  In a dragon boat, I believe most adult paddlers of average leg length can sit on the bench and get the ball of their foot or heel on the forward foot-stop with some knee flexion (aka bend).  I intend to take some metrics of our BuK boats to point out any discrepancies row to row (but that will have to come later).  By having one or both knees flexed, this decreases tension on the hamstring(s) and potentially allows for a paddler to have more hip hinge before the low back begins to flex.

So in theory, a boat full of tall ballet dancers should have incredible reach!

A Word on Stability

Hip hinging forward with a straight back is not all about flexibility.  Paddlers will also need good core stability to keep the spine neutral.  If a paddler is found to be quite flexible but is seen to “hunch and crunch” during their stroke, it may be that they are lacking muscular stability to control their bodies through their range of motion.

Conclusion

Whether you’re interested in obtaining more reach or developing adequate flexibility to prevent injury, stretching your hamstrings dynamically prior to a workout and statically after a workout is an essential part of your dragon boat dry land training.

References:

Youdas JW, Krause DA, Hollman JH, Harmsen WS, Laskowski E.  “The influence of gender and age on hamstring muscle length in healthy adults.”  J Orthop Sports Phys Ther. 2005 Apr;35(4):246-52


Power Slings

If you read this well-written article,  you can start to wrap your brain around how these structures relate to paddling specifically.  If you read it and are confused, don’t worry.  In a nutshell, we have groups of muscles that run along the front and back of our bodies that run in a diagonal direction.  Visualizing them on either side of midline, we can see an “X” pattern that forms across our front and back.  Contracting different arms of the X’s allows us to flex, rotate, sidebend, and extend as well as resist external forces that would otherwise move us in those planes.  This X-pattern has been referred to as an anatomical “sling” or sometimes as a power-sling.

Power slings run across our front and back to provide strength and stability

Power slings run across our front and back to provide both strength and stability.  Adamantium provides the rest.

Paddling, like all sports, is 3-dimensional.  Taking a stroke involves muscle action and movement that is tri-planar.  It can be reasoned that by contracting in various patterns, these slings work to stabilize and move our body in 3 dimensions.  What this means is that training in a cross-pattern or diagonal/asymmetric fashion may be more functional and directly applicable to developing strength, performance, and stability in a 3-dimensional sport.

During the recovery phase of the dragon boat stroke, a paddler will flex forward at the trunk as they rotate to face inside the boat.  The act of reaching during the recovery phase (in a left sided paddler) can be thought of as contracting the front sling running from left shoulder to right hip.  Acting alone, this sling would cause the trunk to curl forward, drawing the left shoulder towards the right knee.  To maximize reach by keeping the spine more neutral, the posterior (rear) sling running from right shoulder to left hip must contract to draw the right shoulder blade and top arm up and back (coincidentally establishing positive paddle angle on the reach) keeping the spine straight and long.  The opposite set of slings work for a right-sided paddler.

During the pull phase, the slings quickly and powerfully switch actions.  The front sling running from right shoulder to left hip contract to drive the blade down into the water, initiating the pull.  The rear running from upper right to lower left contract to pull the trunk upright, preserving the rigid A-frame.  Different stroke styles involve different coordination of these slings, but still rely on these slings for movement and stability.

If a paddler is deficient in strength of one or more of these slings, it’s simple to see how this can contribute to visibly faulty paddling technique or simply less power delivered into the water.  Likewise, faulty technique as well as muscular imbalance and lack of stability can lead to an increased risk of injury.

In the future, I’ll be aiming to make some educational media about stretches and exercises to condition these slings.


Anatomical Slings

Looking to understand your functional anatomy a little better? Read this article!

For awhile now, we’ve been delineating hand to foot continuities that run throughout the body, providing strength, flexibility and a more developed sense of one’s body in space as they unfold. These patterns of uninterrupted flow, created by sequences of muscle, tendon, fascia and bone, come and go with movement.

We saw, last time, how motion of the hands helps create lines of pull that travel by various routes up into the torso. Our task today is to look for some of the strings that will convey these impulses from the torso down into the pelvis, legs and feet.

Back of the torso

A good place to start is at the back of the trunk. Remember that you can enlarge an image simply by clicking on it.

The next two drawings provide an overview of what Myers calls the Back Functional Line. Both illustrations reveal the same continuous line of pull running…

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