By Andrew S. Zolnay, Ph.D

The generation, transmission, and measurement of power will be discussed as these apply to rowing ergometry and rowing a racing shell. The use of rowing ergometers for training or team selection will be shown to be unfair and unreliable.

The total power generated by an athlete under aerobic conditions (the quick start energy reserves are all used up) is proportional to the heart rate.

Extensive neural adaptation of approximately two years is required for athletes to earn how to effectively transfer power to propel the boat.  This neural adaptation is altered by ergometer work due to some similarities to rowing.

The athlete's ability to transfer power to the spinning wheel of a rowing ergometer is sensitive to the lad settings.  It is next to impossible to determine the optimum settings for each athlete making ergometer team selection criteria unfair.

The power required to move the body back and forth on the rowing ergometer slide is calculated since this power is not measured by the spinning wheel.  Body motion power is substantial and varies with eight, slide technique, and stroke rate making ergometer scores unreliable. 

The importance of athlete power density (pulling one's own weight) is discussed and a fair and reliable means of measurement is proposed.

Power Generation

The athlete may be considered a biological engine which provides the power to propel the racing shell.  In a race, the most obvious is often forgotten.  The engine needs to breathe and the fuel has to get to the muscles.  A conscious effort to inhale and exhale completely accompanied with relaxation on the recovery is necessary.  Because the veins have one way valves, the contraction and relaxation of muscles moves the blood back to the heart.  If the muscles do not relax, circulation is impeded, fuel does not flow, and power drops.

When aerobic, the heart rate is proportional to the total power generated.  Total power is divided into internal systems power required to maintain life, muscle contractions to brace or balance and move body parts, and finally the power that is transmitted to the oar handle.

Our objective is to develop a high power density ("Lean and Mean") biological engine without injury.  The heart rate when we just wake up is proportional to the power required to keep all our biological systems working.  An elevated hart rate upon waking indicates stress:  perhaps an illness coming on or insufficient rest from the previous day.

Power Transmission:  Neural Adaptation Considerations

The transmission of power from the athlete to the boat depends on the establishment of a stable platform, bladework, and the proper selection of rigging parameters (including inboard/outboard ratio of the oarshaft).  These parameters are interdependent, changing one influences the others.  Adjustments are difficult because any change, at first, manifests itself with a drop in performance followed by a gradual improvement as neural adaptation to the change takes place.  This is true when switching from ergometer work to rowing and vice versa.

The establishment of a stable platform and bladework initially involves learning to row without flipping over.  Later, it is replaced by setting up the boat.  There is a theory, fairly well supported by experiments, regarding the neural adaptation process required to learn basic skills like walking (Ref.1).  It is impossible to explain how to row because neural control is massively parallel (thousands of things going on at once) and our explanations are sequential (one idea at a time).

The sophistication and sensitivity of the neural adaptation process belies explanation.  Small changes such as switching from left over right to right over left in sculling can reduce an athlete to beginner level (Ref. 2).  Neural adaptation processes can be sufficiently similar to be mutually exclusive.  For example, it is impo9ssible to get your "sea legs" on land.  But, after spending time on a ship, you walk funny when back on land.

Although the neural adaptation process is beyond our understanding, how to assist its development in rowing has been known for a long time.  For instance, the exercise required to assure a stable platform (set up boat) involves practicing restoring balance from an imposed lack of balance (Ref. 3).

Unfortunately, the rowing ergometer alters neural adaptation to rowing and there is nothing to tweak, adjust, or change to make this fundamental flaw go away.  Attempts to alter the ergometer to mimic rowing more, end up working against the objective (the sea legs example).

Skiing for winter training is a superior alternative to ergometer work.  Fresh air, marvelously aerobic, and fun, skiing gives respite from the droning drudgery of ergometers, and does not interfere with your rowing skill.

Power Transmission:  The Mechanics of It

Our power production has limitations of force and speed (Ref. 4).  The force limit is exceeded when we attempt to pedal a bicycle up a steep hill in high gear and our speed limitation is exceeded when we attempt to pedal down a steep hill in low gear.  Impedance matching or finding the right gear is also important in rowing but it is done with rigging.

Force divided by speed is the impedance of a machine and force times speed is the power produced.  It is advisable to select rigging and oarshaft inboard/outboard ratio so that the athlete's output impedance matches the boat's input impedance precisely to obtain optimum power transfer as shown in Figure 1 (Impedance mismatch ratio equals 1).

The curve of Figure 1 does not drop off as steeply on the heavy side as on the lightly rigged side (see Ref. 4 or any mechanical engineering text for mathematics).  Rigging boats on the heavy side leaves some room for error but the cost is loss of available propulsive power.

Before the era of ten speed bicycles, with the single gear you had a tough time getting going but once you did you could keep going at a decent clip.  In rowing, the collar is bolted to the sleeve at a location (fulcrum point) that serves racing conditions best (handle inboard for headwind, outboard for tail wind).

The load settings on a rowing ergometer may fit some athletes in the beginning of a trail but as the athlete tires, output impedance drops (can't pull as hard but can still keep moving) and an inevitable impedance mismatch develops reducing power transfer to the spinning wheel.

The existence of an ergometer load setting that selects athletes for best results in rowing competition remains to be proven.  The load an athlete can bear and the loading required for variable race conditions changes.  The solution requires ability to shift the load as in ten speed bicycles.

There is a good reason to verify Figure 1 experimentally on a basic exercise like the leg press machine.  Start with maybe 100 pounds and go for broke on the number of repetitions in five minutes.  Plot on the vertical axis the weight times the number of repetitions in five minutes and on the horizontal axis the weight divided by the number of repetitions in five minutes.  Repeat the test each time you work out on the leg press machine increasing the we4ight by 20 pounds.  A curve resembling Figure 1 should develop.

The weight at which the curve peaks is the weight required for optimum power transfer.  This is the weight you should select when working out on the leg press machine.  Always do enough repetitions to challenge your power producing capability.  When it takes less time to do the same number of repetitions, you have become more powerful and it's time to increase the weight one notch.

Have you wondered about the number of repetitions and weights suggested in exercise programs?  You can figure out what is right for your optimum development.  The same procedures as the leg press example can be done for any other weight exercise.  Power is the key.  Time your entire weight workout.  When you finish your exercises routine in less time, you have become more powerful.  If it takes longer, look carefully for the cause, ease off till you find the reason for the drop in performance.

Measurement of Power with the Rowing Ergometer

The rowing ergometer measures only the power transferred to the spinning wheel via the sprocket and chain.  The rowing ergometer does not measure the power required to move the body back and forth on the slide.  The body motion power on a rowing ergometer varies widely with athlete weight, slide technique, and stroke rate as shown in Figure 4.

From Figure 4, we find that a 100 Kg (220 pounds) experienced athlete on the ergometer at 36.9 strokes/minute produces 196 watts (not measured by the ergometer) to move his body on the slide.  For periods of continued exertion lasting for six minutes, the total power output is generally no more than 373 watts (1/2 horsepower).  The body motion power is more than half of the total power produced by the athlete and it is not measured by the ergometer.

Figure 2 shows the seat, (and the athlete's body on the seat) moving back and forth on the slide of the rowing ergometer.  Just imagine a pencil attached to the seat and someone pulling a large roll of wrapping paper (from port towards starboard) underneath.  The line on the wrapping paper will look like Figure 2.

Figure 3 shows the results of point by point calculations performed on the seat position curve of Figure 2 to obtain body motion work and power.  From physics we know that force is mass times acceleration, work is force times distance, and power is force times speed.  By taking the first and second derivatives of the seat position curve, we obtain speed and acceleration, respectively.  We do the physics with the appropriate multiplications to obtain force, work, and power to move the body as shown in Figure 3.

Figure 4 is obtained by doing the calculations of Figure 3 at different stroke rates and plotting the results.  For an experienced athlete whose body motion curve resembles a sine wave, engineers would expect the body motion power to increase as the square of the frequency (stroke rate).  The square root of power/kilogram is plotted if Figure 4 confirming the engineer's expectation.

For those not so mathematically inclined, an estimate of the power a particular athlete expends moving the body back and forth on the slide of a rowing ergometer can be made by noting the heart rate increase moving back and forth on the slide without pulling the chain.  This heart rate is then compared to the heart rate increase of the ergometer test for the same length of time and same stroke rate.

In conclusion, the rowing engineer does not measure the propulsive, power producing recovery phase of the rowing stroke (top speed of the boat is achieved during the recovery) and alters the athlete's refined sense of how to manage the recovery t effectively move the boat.  Checking the boat is probably the least offensive term that can be applied to the consequences of ergometer training.  Building a sliding rigger equivalent ergometer is even more effective at destroying rowing technique as discussed earlier under Neural Adaptation.

Proposal for Athlete Power Density Measurement

For propulsion purposes, high power density (lots of athlete power from each unit of athlete mass) is important because the athlete travels with the boat.  This concept, however, changes the affectionate term "Engine Room" for the middle four of an eight to "Ballast".

The suggested alternative to ergometer testing must not have the same shortcomings.  Since the musculature of our legs is well suited to carry our body weight (let nature take care of gear selection or impedance matching), pick a hill with sufficient grade that provides near exhaustion to run up within seven minutes.  This is now your National Team Test Track.  All testing must be done at the same temperature and relative humidity with no wind.

Power density is proportional to the inverse of time (1/t), required to climb the hill.  Power density = (acceleration of gravity)(height of the hill)/(time to climb).  The athlete with the highest power density is the one reaching the top of the hill first.

ACKNOWLEDGEMENT

The author is sincerely grateful to Tibor G. Machan, Head Coach of Vesper Boat Club, 1961-1964.

REFERENCES

1. Pelionisz A., Llinas R. (1985) Tensor Network Theory of the Metaorganization of Functional Geometries in the Central Nervous System. Neuroscience, 16, pp. 245-274.
2. Zolnay A. (1987) A Radical Solution to the Left Over Right Asymmetry in Sculling. American Rowing Vol. 19, No. 9, pp. 9-10.
3. Machan T. (1943) Az Evezes Muveszete. Stephaneum Press, Budapest, pp. 1-99.
4. Zolnay A. (1977) Power to the Oarsman.  The Oarsman, Vol. 9, No. 2, pp. 12-15.

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