The Science of Canoeing By Richard Cox

The volume of oxygen that can be absorbed into the blood stream depends upon the volume of blood, the
number of red blood cells and the haemoglobin contained within them. Haemoglobin is the compound to which
the oxygen attaches itself for passage round the circulatory system. The volume of blood, the concentration of
red blood cells and the amount of haemoglobin contained therein are largely determined genetically but can be
increased by training, especially if the correct elements and vitamins for its synthesis are present in the diet (see
p. 101). A most effective way of increasing the red blood cell count is to train at altitude. Concentration of
oxygen in the atmosphere at high altitude is less than at sea level and the body adapts to accommodate this
deficiency by increasing the red blood cell count. The volume of blood that can be passed round the circulatory
system in a given time (and therefore the volume of oxygen and other nutrients carried to the muscle cells) is
dependent upon the 'cardiac output'. This is determined by the stroke volume (the volume of blood squeezed out
of the left ventricle in one contraction) multiplied by the heart rate (the rate at which the heart contracts).
Ability to work the heart at speed is something one is born with; it is a reflex action to prepare the body to fight
or for flight when in danger. Ability to sustain a faster than normal heartbeat during exercise is something that is
acquired through training. (l)
Continuous sub-maximal work for periods in excess of three minutes is the type required for developing the
cardiovascular respiratory system. The number of sets and/or repetitions within each set is usually large
extending in total to over 40 minutes of exercise. Intensity should be just below that level which causes the
athlete to establish an oxygen debt. Very roughly, the aerobic threshold (expressed by pulse rate) can be
calculated from the following formula, where exercise heart rate should exceed the sum of the resting heart rate
and 60% of the difference between maximal and resting heart rates:
Heart Rate in Exercise = Resting Heart Rate + 60% (Max H R . Resting H.R.)
The maximum heart rate is estimated as 220 minus age in years.
Figure 5.16 shows maximal heart rates and training sensitive zones for use in aerobic and anerobic training
programmes for people of different ages.
Recent evidence suggests that this graph best relates to running, swimming and cycling exercises. The
maximum heart rate for canoeing which uses a smaller muscle mass averages 10-13 beats per minute less.
Thus, for a 20 year old canoeist whose resting heart rate is 50, his/her aerobic threshold would be -
50 + 60%[(200-13)-50] = 132.2
Whilst cardiovascular fitness can be improved using many different forms of exercises so long as it raises the
heart rate and maintains it at an appropriate level for a long enough period, it is more effective if large muscle
groups are used. This is because these muscles are usually the only ones with enough local endurance to be
(1) For details of pulse rates achieved in international competition by sprint canoeists see p 174