The Circulatory System

The circulatory system can be divided into two parts; the arterial system, and the venal system. The heart is two pairs of pumps, one pair of pumps receives blood from the body via the venal system and pumps it through the lungs. Here it gives up carbon dioxide and collects oxygen before returning to the heart to be pumped around the body via the arterial system. The arteries branch down into tiny capillaries, which yield up the oxygen and nutrient in the muscle before joining up as veins.

In training for rowing the heart lung function is very important. The aim of the training should be to increase the amount of blood pumped around the body each beat, (stroke volume), and to increase the amount of air moved in and out of the lungs, ventilation equivalent (Ve).

The best type of training to achieve this is training which elevates the heart rate to around 85% of heart rate maximum.

Blood is a complex fluid made up of amongst other things red blood cells. Every red blood cell contains haemoglobin, a complicated protein that carries oxygen. Haemoglobin is partly made from iron, and accounts for about two thirds of the body's iron supply.

The average man at rest uses 250ml of pure oxygen and gets rid of almost the same amount of carbon dioxide, the chief by-product of the combustion of foodstuffs. Haemoglobin (Hb), combines reversibly with oxygen and over 96% of the oxygen is carried in this form, the remainder being dissolved in the blood.

Athletes are prone to iron deficiency because regular exercise increases the body's need for iron in a number of ways - for example, hard training promotes red blood cell production, while iron is lost through sweating.

A heavy training schedule can improve an athlete's sport-specific fitness dramatically, but it can also have an unwanted effect; hard training can actually suppress your immune system, putting you at greater risk of developing an opportunistic infection which could decrease your quality and quantity of training and even force you to miss a key competition.

Improper nutrition can compound the negative effect of strenuous exercise on the immune system. For example, athletes who fail to include enough carbohydrate in their overall diets suffer from larger increases in blood levels of immune-system-suppressing 'stress hormones'. When extreme training is combined with poor nutrition, it becomes increasingly difficult for athletes to avoid illness. Naturally, athletes can increase their chances of staying healthy by following a diet which is adequate for carbohydrate, protein, and fat, as well as vitamins, minerals, fibre, and antioxidants. Sports-nutrition experts have also suggested an additional strategy for staying well: taking in carbohydrates during intense or prolonged workouts.

Muscle mass accounts for about 40% of the total body weight and muscles fall into four main groups. Prime movers cause active movement when they contract. Antagonists oppose prime movers returning the limb to its original position. Fixation muscle steady one part as a base for movement caused by other muscles. Synergists work with prime movers to fix joints and prevent unwanted movement.

When training the muscle we want to familiarise the prime movers and antagonists with the load, range and speed of contraction needed in rowing. We also want to develop the fixators and synergists through core stability exercise routines to stabilise the body to achieve the maximum transfer of power. Muscular development can occur in two ways; an increase in the cross sectional area of the muscle fible and increased capilliarisation.

An increase in cross sectional area can be achieved through strength training of which weight training is highly effective, The benefits are that for a given load less fibres will be recruited or for a given number of fibres a greater load can be overcome.

Increased capilliarisation is brought about by endurance type training. Capilliaries run alongside the muscle fibres carrying nutrients and oxygen where they are given up. The more capilliaries the greater the contact time for this process to take place.

Mitochondria are bacteria-sized organelles randomly located within the muscle structure. Mitochondria make efficient use of nutrient molecules, requiring oxygen in the process. They are, in fact, why we need oxygen at all. Endurance training also has the effect of organising the mitochondia close to the capilliaries which speeds up the cross over of nutrients and oxygen.

The body reacts to exercise demmands and so when you are sitting on the start your heart rate is relatively low. On the word go you pull the hardest stroke of the whole race and so imediately there is an oxygen debt. The fuel for exercise is adenosine triphosphate (ATP) and initially this is derived from creatine phosphate supplies stored in the muscle. For argument sake we can call this phase 1.

In a short time the local supplies of both ATP and creatine phosphate become drastically depleated. The lack of oxygen severly restricts the limits of ATP production from other pathways and yet repeated muscle contraction can continue as a result of glycolysis. This process enables ATP to continue to be produced at maximum rate in the absence of oxygen. The end product of glycoysis is lactate and this accumulates in the muscle.We can call this phase 2.

When we slow down the exercise there is an abundance of oxygen where the lactate is oxidised to carbon dioxide and water. This is the final phase, phase 3.

These are the three energy systems, phase 1 is sometimes refered to as the "fright and flight" system. When you come off of the start you can go as hard as you like for about 15 strokes without fear of the debilitating effects of lactate. This is only available at the start so you might as well make use of it. Some people believe that there is a CP supply that will last for about 20 seconds and they can call on 10 seconds of this at the start and the other 10 seconds at the finish. This is absolute nonsense.

We then move into phase 2, the anaerobic system, where we can still carry on flat out but we will suffer the debilitating effects of lactate accumulation. If we were only racing for about 1 minute it would be OK but if we intend to go on longer then you have to make a decision of how much lactate you can tollerate and carry throughout the race. This has to be balanced against the advantage of being ahead and blowing your doors off.

The final phase 3 is the aerobic phase where there is sufficient oxygen to sythesise the lactate produced and keep it at a manageble level.

I have mentioned the debilitating effects of lactate production without explaining what it actually does which is to alter the blood pH.

Blood pH levels are pretty involved chemistry, however all we need to be concerned with is the fact muscle and blood pH are strictly controlled within narrow ranges. Homeostasis (normal) pH is 7.4. When we subject the muscle to hard exercise, large amounts of glucose are utilized to generate ATP (the energy molecule of the Krebs Cycle) very quickly. To obtain this large amount of energy the glucose molecules are spit in half to produce two molecules of lactic acid. The research on working muscle shows that the accumulation of lactic acid in the muscle causes pH levels to drop. A lower pH means an increase in Hydrogen ions in the blood and/or muscle (that's what the 'H' stands for). This is shown to interfere with the contractile force of muscle fibers, gradually preventing further contraction until movement ceases.

Muscle fibres are grouped together in bunches called myofibrils. When examined under a microscope you can se that the myofibrils are made up of a series of bands. These bands are actin and myosin. Muscle contraction takes place when on reciept of an electrical stimulus from the brain the tenticles on the myosin lattice move. As they move they draw along the actin lattice. This tiny action is repeated throughout the length of the muscle combining to move the limb over its full range.

Calcium is the bonding agent between the actin and myosin and this bond is broken if the blood ph become too acidic. Once the bond is broken, although the myosin is still receiving the electrical stimulus it does not move the actin and so no movement of the muscle takes place.

Aerobic and Anaerobic Metabolism

With moderate exertion, carbohydrate undergoes aerobic metabolism. Under these conditions, oxygen is used and the carbohydrate goes through the pathway of anaerobic metabolism in which glucose is converted to lactate. If there is plenty of oxygen available and the exercise is of low to moderate intensity, then the pyruvate from glucose is converted to carbon dioxide and water in the mitochondria.

Aerobic metabolism supplies energy more slowly than anaerobic metabolism, but can be sustained for long periods of time up to 5 hours. The major advantage of the less efficient anaerobic pathway is that it more rapidly provides ATP in muscles by utilizing local muscle glycogen. Other than creatine phosphate, it is the fastest way to re-supply muscle ATP levels. Anaerobic glycolysis supplies most energy for short-term intense exercise ranging from 30 seconds to 2 minutes. The disadvantages of anaerobic metabolism are that it cannot be sustained for long periods, since the accumulation of lactic acid in muscle decreases the pH and inactivates key enzymes in the glycolysis pathway leading to fatigue. The lactic acid released from muscles can be taken up by the liver and converted to glucose again, or it can be used as a fuel by the cardiac muscle directly or by less active skeletal muscles away from the actively contracting muscle, (shunt mechanism).

Muscle glycogen is the preferred carbohydrate fuel for events lasting less than 2 hours for both aerobic and anaerobic metabolism. Rowers are training to become efficient carbohydrate burning machines.

Depletion of muscle glycogen causes fatigue and requires 24 hours to restore glycogen stores to pre exercise levels. Athletes training up to once a day can safely follow a high intensity programme but training more that this requires the intensity of the sessions to be reduced and very carefully monitored.

Both the nutrition and conditioning of the athlete will determine how much work can be performed in a specific exercise before fatigue sets in. This can be measured directly or indirectly. An indirect measurement uses the rowing machine according to standard protocols and heart rate is monitored.

The more conditioned athlete can produce the same amount of work at a lower pulse rate. This indirect determination assumes that pulse rate is proportional to oxygen consumption. On the other hand, oxygen consumption can be measured directly during exercise. A step test on a Concept 2 rowing machine is used to increase the intensity of exercise until fatigue occurs. The amount of oxygen consumed just before exhaustion is the maximal oxygen uptake or VO2max. Exercise intensity can be expressed as a percentage of VO2max.

Estimation of Maximum Oxygen Uptake

It may be necessary to have someone with a note pad available to take down some results during the running of the test.

Equipment

Concept 2 rowing machine with the drag factor set to between 130-140. The exercise time on the performance monitor should be set to 6 minutes and the display set to show 500m split time.

Heart rate monitor and interface connected to the monitor.

The test requires the individual to row for 6 minutes at a speed which will raise the heart rate to 80-90% of heart rate maximum. To determine your heart rate maximum the following procedure should be carried out at least 48 hours prior to the test.

How to determine your HRM on the Concept 2

For the best results the athlete should carry out the same procedure for the 48 hours before the test. This will include,

1. Being in good health
2. Being well rested with no heavy training sessions in the previous 48 hours
3. No alcohol consumed in the previous 24 hours
4. No strong coffee or tea in the preceding 3-4 hours

You need a heart rate monitor and interface. Having checked that the heart rate monitor is working complete a warm up paddle for 5mins making sure the heart rate does not exceed 140 BPM and record the 500m split time that corresponds to this heart rate.

Start the test by rowing at the split you recorded from the warm up for 1'30secs. And note the heart rate. At the end of 1'30secs increase the effort by 25 watts (watts to split time is shown in the training guide). Repeat this process until the athlete reaches exhaustion and record maximum heart rate.

The target heart rate to elicit the required intensity is calculated by deducting the resting heart rate from the heart rate maximum. Multiply this figure by 80-90% and then add the resting heart rate.

e.g. HRM = 200, RHR = 60
200 - 60 = 140 x 80% = 112 + 60 = 172
200 - 60 = 140 x 90% = 126 + 60 = 186
Therefore the target range is 172-186

Warm up

Row a total of 8-10 minutes on the machine raising the heart rate to twice the resting rate. Carry out some stretching to suite your individual needs then row again for a further 5mins. By which time you should be ready to start the test.

The Test

The individual should row at a speed that brings the heart rate into the required range between 4-5 minutes of exercise. If the exercise does not raise the heart rate to this target range the error of the estimate increases.

Row for a total of 6 minutes keeping the split time as constant as possible.

Record the heart rate after 5 minutes, 5'30 and at the end of the 6 minutes test. Add the three heart rates together and divide by three to get the average heart rate. Press, "Recall" on the monitor and the across arrow and read off the meters rowed in the last two minutes.

Using the Nomogram

If you have rowed competitively or have been using the machine regularly for two years then consider yourself a rower. If rowing is not your sport classify yourself as a non-rower.

On the left hand line of the nomogram mark your average heart rate response for the exercise.

On the right hand line of the nomogram mark the distance rowed in the last two minutes.

Draw a line to connect the two points.

At the point where the line crosses the middle line read off the estimated maximum oxygen uptake.

If you consider yourself a non-rower then read off of the left hand side of the centre line, if you are a rower then read off of the right hand side.