Fitness for Kayaking [50]

Myths and Hard Realities

By Trevor Gardner

So you want to improve your kayaking performance. This will mean different things to different people. The Wednesday night Lane Cove River Mirage time triallers probably want to go faster over a known and relatively short distance. The South Coast Bruisers need to be able to tab away in foul weather for hours on end for days on end. The Wollongong Pod Sandon Point surfers probably want to avoid tearing their arms out of their sockets in three metre swell. The overweight corporate desk paddlers need to lose weight and make slow improvements in their general health. Well, there is something for everyone. Read on.

The human body is a combustion engine. Your very own Mark 1 power plant, given to you at birth, it is the only one you are going to get. If you stuff it up you can’t trade it in like your car. However, just like your car you burn carbon based fuels in oxygen and produce carbon dioxide and water. You too are a greenhouse gas emitter.

Factory fitted, your body has a duel fuel system with short and long range tanks. In the main, fuel selection and utilisation is automatic and seamless. However, a little bit of knowledge can assist in maintaining optimum performance. Perhaps surprising to some, it is entirely possible to undergo major, sudden decreases in engine output whilst having enough fuel in store for weeks of work. With a little bit of effort and sweat on your behalf you can improve the performance of your engine and improve the efficiency of fuel utilisation.

Whilst you may be able to improve the efficiency and optimise the performance of your Mark 1 power plant there are some basic immutable limitations that must be accepted. Kayakers, like rowers, apply their power without much regard to gravity. Lesser mortals, those undertaking land based activity, expend a lot of energy overcoming gravity. This means that different land based sports require different body morphology for optimum performance. Long distance runners are small, thin and lightweight while 100 metre sprinters have large muscle mass with limited endurance. This doesn’t mean long distance runners can’t sprint and sprinters can’t run long distance. One body type and training style will favour better performance in each sporting discipline.

In kayaking, like rowing, it’s the size of the engine that counts. If a bigger engine is fitted to your kayak any extra weight is relatively unimportant and so the bigger the engine, the faster you go. There is no advantage in being small and thin for long distance touring as you are not lifting your own body weight against gravity. The big V8 paddler running at 50% power setting will find it easier than the 4 cylinder paddler running at 75% power setting to maintain the same speed. This assumes that all else is equal. In reality, paddlers who train regularly, are fit, flexible and exhibit good technical ability will be of little disadvantage on the average paddle. However, if the V8 paddler is at the same standard of preparation then the 4 cylinder paddler will have slower top speed and have to turn out more watts/kg in the cruise. If you are part of a multi-day, multi person open sea trip you might want to check the size and fitness of the engines driving the kayaks in your group.

You may also want to consider the on-board computer controlling the kayak engine as well. Is it a group-conscious computer or an every-man-for-themselves type computer. This might override fitness aspects in group spread.

Time to put a few numbers and equations down to provide some terms of reference for what is to come. I mostly round out numbers, give ball park figures and, unless stated otherwise, the data refer to the medically mythical 70 kg young male adult. Women can reduce numbers by about 25% for muscle mass, calories burned, fuel required, strength and the like. Physiologic fact, not any misogynistic ideology.

I will use Calories instead of kilojoules much to the despair of the scientists amongst you. Calories with big C are 1,000 calories, little c. That is, the big C is 1 kcal but usually just called Calories (Cal). You will either see Calories or kcal on the label of foods but they are the same thing and relate to kilojoules (kJ) as: 1 Cal = 4.2 kJ.

How many Calories do you need every day? Basal metabolic rate for our mythical 70 kg paddler is 2,000 Cal. This is to lie in front of the TV. Add on a bit for getting about and 2,500 Cal is the often quoted figure but will depend on how active you are during the day. This is about 100 Cal/hour. How should we fuel this paddler. Standard wisdom says carbohydrate (CHO) 50% (or more), fat 35% (or less) and protein 10-15% (about 1 gram/kg body mass). These percentages relate to calories not grams.

What about the energy density of these fuels. Carbohydrate (CHO) is a bulky inefficient storage substrate with about 4 Cal/gram. Protein also gives 4 Cal/gram. Fat is anhydrous (without water) and stores 9.1 Cal/gram (call it ten for doing the sums in your head). Thus, you need about 300 grams CHO, 80-90 grams fat and 70 grams protein per day. Only about 2% of caloric needs for exercise come from protein in the first 90 minute but this can rise to 15% or so after 90 minutes of sustained exercise. Alcohol, for the record, provides 7 Cal/gram.

The muscles use mostly fat as their fuel when pottering about (as free fatty acids liberated from stored triglycerides in adipose tissue and free fatty acids stored within muscles). The brain uses about 90% of the blood sugar and red cells the other 10% when at rest. There are about 100,000 Cal of fat stored on our lean paddler, could double that on some more padded paddlers. Clearly, a fat deficiency is not likely to occur under any conceivable paddling expedition. Six hours paddling a day, three weeks might need about 3 kg of stored fat. About half the energy requirements come from CHO when exercising but this percentage increases with increasing exercise intensity.

How much CHO can we store? Not much is the answer and this is very important for paddling endurance. The muscles store CHO as glycogen; 400 grams in muscle, 100 grams in liver. This is about 2,000 Cal. For various tedious biochemical reasons, fat metabolism during exercise requires the intermediaries of carbohydrate metabolism. If you exhaust your CHO stores then fat metabolism suffers as well. Excess fat in your diet is stored as fat, excess CHO is stored as fat. Fat cannot be catabolised to CHO so you need the right amount of CHO to balance your requirements. An excess of 3,500 Cal will lead to about 400 grams of fat.

Now a look at training. In 1968 Dr Cooper, a US Air Force physician produced a book titled Aerobics. He contended that cardiovascular conditioning was important and that everyone should perform regular aerobic activity. Dr Cooper’s concept of aerobic activity was any continuous exercise that required relatively heavy breathing. The exercise needed to be vigorous enough to raise the heart rate above 70% of the predicted maximum. This concept remains the basis for cardiovascular conditioning. There are lots of trendy programs, theories and myth associated with training. Vast amounts of literature is available on the subject. Despite all of this, the basis of useful cardiovascular training involves continuous aerobic exercise (jogging, rowing, cycling, paddling, swimming, etc) of at least 20 minutes duration, with a heart rate of 65-70% maximum or greater and at least three days per week. This is the threshold for increasing cardiovascular fitness, less than this and biochemical and anatomical changes associated with increased fitness will not occur. The body is a machine of adaptation, both up and down. If you don’t use it, you lose it.

An increase in fitness is demonstrated by the ability to perform more work for the same oxygen consumption and heart rate. The enzymes of fuel utilisation can be increased and the physical mass of the heart muscle and its pumping performance can increase. This allows an increase in the oxygen delivery to support an increase in the maximum output. Your pump (heart output) can increase from about 22 L/min to 35 L/min. Your absolute maximum oxygen consumption is genetically determined. What you do with what you have is up to you but not all of us will make the Olympics despite the most expensive sports psychologist with a cattle prod.

Significant increases in fitness can occur in as little time as three weeks, so it is always worth putting in some yards before a big paddle. After about three months of regular training you will be on the plateau and unless you push you training up a notch you will maintain the level you have reached. The ability of muscles and tendons to deal with a sudden increase in regular exercise may lag behind biochemical changes and lead to strain injuries. A graded approach is always advised if you starting from a level of inactivity. This allows time for anatomical and structural changes in the muscles and tendon inserts.

Reference is often made to the VO2max, the maximum oxygen consumption, mentioned above. Remember, the muscles are burning oxygen and producing heat and greenhouse gases to move that kayak. Usefully, oxygen consumption has a linear relationship to heart rate, given by the equation: %HRmax = (%VO2max + 28.12)/1.28.

The amount of work you can perform and the amount of oxygen you can utilise is determined by genetics, the size of your muscle mass, your training effort and your age. Your maximum heart rate has been shown to be predicted by the simple equation of 220 – your age. The 40 year old will have a maximum predicted heart rate of 180 beats/min. You can see from the two equations above that as you age your maximum oxygen consumption decreases, reflecting a decrease in the amount of work you can do. Fact.

50% of VO2max (%HRmax about 60%) seems to be the accepted threshold to stress the cardiovascular system enough to make improvements in fitness. A minimum heart rate of 65-70% max predicted is a better target I believe. Duration wise, 20 minutes is the minimum useful time. The process of lipolysis, the breaking down of stored fat to useful fuel units for the muscles, takes 20 minutes to ramp up. Ideally then, 30 minute sessions with your heart at least 65% of your predicted maximum is the go. At this rate of effort there are about equal amounts of CHO and fat burned. As you increase intensity, there is a greater percentage of CHO burned but at this higher level of calorie expenditure you will burn more fat overall than you would have at the lower intensity. 85% HRmax is the usual upper end of the training range. Three days a week is the minimum remember. There are recognised general health benefits for doing less than the above but you will not see increases in cardiovascular fitness in the strict sense.

How does all this theoretical rot translate to the real world? I have used myself as a kayak test dummy and have some preliminary data. I also have good data from a rowing ergonometer. All data was recorded after at least 20 minutes of target heart rate warm-up. I am the average middle-aged male, 41 years, weight 84 kg with fitness somewhere in the middle to lower side between sloth and athlete. My training heart rate range is 116-152/min (55 to 80% VO2max). At HR 116 I burn 670 Cal/hour (110 watts of work). At 80% HR max, 143/min (75% VO2max), my calorie burn rate is 880 Cal/hour (170 watts).

In the future I will have data for correlating different kayaks, their speed, heart rate and calorie consumption. Preliminary data shows that paddling a Mirage 530 on flat water at 7 km/h requires only a heart rate of 100-105 for me. This is below my training heart rate lower limit of 116 and even below the 50% VO2 max. My guess is a burn of about 500 to 550 Cal/hour. These numbers are important for highlighting that just being on the water paddling may not provide much improvement to your cardiovascular fitness. You can now see that if you only paddle on the weekends (2 days) and don’t push the heart rate up then there will be little, if any gains in cardiovascular fitness. This is not to say that you don’t gain improvements in general health but don’t kid yourself that you are improving your endurance to any significant degree.

For those looking to lose weight, have a look at the grim details. At 500 Cal/hour burn at the cruising 7 km/h I was utilising about 250 Cal/hour of fat. This is about 30 grams fat for the hour. So, five days a week for an hours paddling will burn 150 grams fat. Six weeks to drop a kilo. In fact, regular exercise raises the metabolic rate and you will probably burn a little more than that but there are no quick fixes. A burger at Maccas will cost you about 30 grams fat.

Another feature of aerobic training is that the low resistance, high repetition pattern is not especially good at firming and toning if that is what you are after. Further, if used as a technique in isolation, aerobic training can lead to a loss of muscle mass, as seen in the scrawny but very fit marathon runners. Remember the deal with the size of the engine being all important in kayaking. This is the reason some resistance training is a good idea. At least two days a week of free weights to add strength and mass is a good idea. When added to your regular aerobics training you become a killer paddler.

A very brief mention about flexibility. If you train without stretching you will shorten your muscles. This limits range of movement, inhibits maximum performance and predisposes to injuries. Get someone to show you how to stretch properly if you don’t know how. Warming up and cooling down should also be routine for all paddling/training.

How about endurance events. The Hawkesbury Classic or paddling down the coast in some moderate swell and sea might see you paddling with a sustained heart rate of 70% predicted max or more. For me this is about 125/min. When I paddled from Jervis Bay onto the exposed coast heading south my heart rate went from the 100-105 at 7 km/h to 125/min at something less than 7 km/h. For me this is a burn of 740 Cal/hour. At this intensity I am burning about 500 Cal/hour of carbohydrate. At higher heart rates the proportion of CHO used is higher and fat utilisation becomes inhibited as well. This is where the cardiovascular fitness training shows its benefits, providing higher outputs at lower heart rates.

Under the conditions above I am going to ‘hit the wall’ after just a few hours. This is commonly seen in the Hawkesbury Classic (111 km overnight endurance event). Not only are the limited CHO stores used up (2,000 Cal) but invariably paddlers do not drink enough. As a rough guide, not accounting for high heat or humidity, you need about 1 ml of fluid for each Calorie burned. My 7 km/h cruise needs about 500 ml/hour and my coastal push about 750 ml/hour. These are what I would consider to be the bare minimum. Realistically, a safer amount would be half as much again.
If you don’t eat and drink but only paddle for a few hours then when you stop you can make it up. But if you are still on the water when you fade, you may well be in trouble. You will not make up the deficit and ongoing losses if you have to keep paddling. Acute weight loss while exercising is due to water loss. A 1% dehydration leads to 2% decrease in performance. This can be in as little as one hour. A 7% fluid deficit will cause a 30% decrease in performance and marked incoordination. You are also at greater risk of hypothermia. Your body is about 70% salty water. A great deal of effort goes into maintaining this wet environment, it doesn’t like dehydration.

Thirst is a late indicator of dehydration and kicks in at about 500 ml fluid deficit. You need to make a conscious effort to maintain hydration. What fluid to drink? Simple answer, isotonic drinks of sodium and carbohydrate. The one hour potter-about paddle doesn’t matter, drink water or whatever. The so called sport drinks have a great advantage over water when you paddle for more than an hour or so. Good studies show that while exercising, people will drink water as freely as sport drinks but not enough of either. After exercise, people will drink 60% less water than isotonic sport drinks. It seems that water quenches the thirst leading to less being consumed. In either case, too little fluid is drunk when left to thirst.

The other advantage of sport drinks is the simple carbohydrate solution can assist in delaying fatigue and improve recovery post exercise. The sodium salt is not for replacing salt loss, which is minimal but to assist in retaining water in the body. Plain water can lead to a decrease in the serum sodium concentration which can paradoxically lead to an increase in urine output of water. The sodium added, like the glucose, also optimises the rate of fluid absorption from the gut, providing an optimum solution for the transport mechanisms in the small bowel. The concentration of carbohydrate should be between 5% and 8%. The lower end while paddling, higher end for recovery. Soft drinks, juices or solutions of carbohydrate greater than 8% will lead to delayed absorption and should not be used. 50 grams of sugar in a litre of water with a pinch of salt will make a home brew. Otherwise, buy the tins of sport drink powder and you can make up your own solution a bit weaker or stronger as required.

The proprietary sport drinks have between 260 and 290 Cal/1,000 ml. So, for me, paddling at 70% of max heart rate (60% VO2 max) using about 500 Cal/hour of CHO, a litre an hour will provide about half my carbohydrate needs. This is probably a very good use of sport drinks when on a sustained paddle. You need to drink by the numbers, not by your thirst. In any case, you can now make ball park estimations of your hourly Calorie expenditure, about half this (or more) is CHO, and then aim to drink enough fluid with some CHO in solution and make up the difference with munchies of your choice. When eating carbohydrate you may find it of benefit to drink water with the food rather than sport drink. This requires two fluid sources but probably worthwhile. All the training in the world will come unstuck if you don’t eat and drink you way through a long, hard paddle.
Are there any drugs that I can take legally to improve performance? Caffeine is the only proven drug that is worth taking. Caffeine does appear to assist in fat utilisation by increasing circulating free fatty acids (FFA), increasing the flux of FFA and increasing the oxidation of FFA in the muscle. Carbohydrate is conserved and time to fatigue is increased. All good stuff. 250 mg appears to be an effective dose, about a strong brewed coffee. All the rest appears to be bollocks. Usually expensive bollocks.

Finally, is there any benefit in using a heart rate monitor? I certainly think there is a place for a simple, non-invasive monitor. There can be a tendency to geek out too much on the technology and not go out and do some hard yards. But as an adjunct to training they do have a place. Despite what some people say, it can be very difficult to know what your heart rate is during a paddle under different conditions. In my case, I used the heart rate monitor to find training levels within my effective training range and then establish Calorie usage at these levels. With this information I can predict how much fluid and food I need on longer paddles. I also found out that my casual 7 km/h was not doing me any use as a training paddle with respect to improving cardiovascular fitness.

Another use of the heart rate monitor is to assist in logging your training progress. On a rowing machine you can row a fixed distance and see the times come down or row to a time and the distance should come up. Importantly, as you improve in fitness your heart rate will fall for the same training session. Training to a specific heart rate can be very useful. You know you are in the training range and doing good and over time either the distance you go will increase or the times come down. The same technique can be used on your favourite training paddle. If your heart rate is not in the training range then fitness will slowly be lost. Very unfit people can find that they don’t have to do very much work at all to get the heart rate into the training range. This can prevent going out too hard and becoming disheartened by the pain and suffering. There is also a positive reinforcement in seeing workloads increase for the same heart rate.

If you are into long distance paddles, whether on open water or closed, the heart rate monitor can alert you to a failure of your hydration/fuel maintenance. If the heart rate starts increasing for the same paddling speed or your speed drops off for the same heart rate then the odds are fuel starvation or dehydration is the culprit. Mind you, you will probably feel pretty stuffed as well.

The take home messages:

  • The more muscle you have the faster you can go in a kayak.
  • Any exercise is better than none.
  • Aerobic exercise at least three times weekly, at least 30 minutes, at least 65% of predicted maximum heart rate, will improve your cardiovascular fitness.
  • Resistance training will add muscle mass and strength.
  • You have months of fat but a day of carbohydrate in the tanks.
  • You need carbohydrate to keep everything running.
  • Dehydration is bad, permissive and avoidable. Drink by numbers, not thirst.
  • Most paddlers probably burn between 500 and 750 Cal/hour on average.
  • Know what you are eating and minimise the fat.
  • Sport drinks are useful for maintaining hydration, performance and aid recovery.
  • Heart rate monitors are OK but hide them from friends to avoid ridicule.
  • I paddle near good coffee shops for a valid reason.

Check out Food for Thought: How to Maximise Your Paddling Energy, by Sharon Trueman: Issue 44 of NSW Sea Kayaker.