Training > Bike

Power Surge

If you can increase your power, and apply it effectively, you'll soon slash those bike leg times. Dr Auriel Forrester explains how to up your work rate

A fast bike leg is crucial to a good triathlon performance. The bike is the longest leg of any race so the winner is likely to be the person who can produce the most power, or at least the most power relative to their weight, while on two wheels.

Top cyclists and, increasingly, top triathletes such as Ironman Champion Normann Stadler and Faris Al Sultan, base their training and racing on power. Power is the rate of work being completed. That work is the effort it takes to move yourself from one point to another and overcome friction and drag. How fast you can do that work is referred to as power and is measured in units called watts.

Riding up a hill at a given speed requires a certain amount of power. That amount is always the same - no matter who the cyclist is and what bike they happen to be riding. However, to ride up the hill twice as quickly requires twice the power, as you have to condense the work into a shorter time. In other words, you're doubling the work rate either by pedalling quicker (increasing your cadence) or pushing a bigger gear, or a combination of both.

Measuring power

The most popular method of measuring effort on the bike is by monitoring your heart rate. While this is very effective in determining how hard you're working, heart rate is fraught with complicating factors. Your heart rate is the end result of the effort, not the effort itself and, as such, is affected by many things including diet, temperature, hydration and mood.

Measuring the actual forces you apply to the bike provides a much more accurate means of monitoring effort. Heart-rate monitoring then takes on new meaning: it becomes a measure of the cost of the effort - the lower your heart rate at any given power, the less effort has gone into producing it.

There are various devices on the market that allow you to measure your power. But even without costly power-measuring tools, you can still perform a meaningful self-test by riding a specific route over a known distance. Make sure this is circular or out-and-back to ensure that you're riding through even weather conditions, and try to do the test on a calm day. After a thorough warm-up, ride the route to the best of your ability and record your time, average speed and average heart rate.

Alternatively, you could do a 15min time trial on an indoor trainer. Aim to ride flat out but try to pace your effort over the full 15mins. As you get fitter, your average speed will increase, which means your sustainable power output rises. Alongside this, your average heart rate shouldn't be significantly higher, meaning you're producing more power/speed for the same effort. While you'll notice improvements in your average heart rates and speed, you won't be able to put a figure on your increased power without a specific power-measuring device.


Doing this type of test once a month during the off-season will help you monitor your training and also provide a quality effort session. During the season, race times will provide a platform to monitor your improvements (or otherwise). However, it's a good idea to repeat this test session every now and then to keep an eye on your progress.

Scientific research has shown that the peak power you can sustain for 15-20mins is a very good indicator of fitness, regardless of the distance you intend to compete over. This is because there's a greater correlation between the power you can hold for 20mins and the power you can hold for an hour or more, than there is between the power you can sustain for 1min and 5mins.

So in order to improve your bike split, you need to gear your training towards increasing your sustainable power. And the good news is you don't have to have a power meter to be able to do this [see 'Test your power' box on p45 - Ed].

Bike faster

There are three key factors in posting a fast split time for the bike leg:

• Pacing

• Aerodynamics

• Power (watts), in particular power-to-weight ratio (watts per kg)

Pacing is about knowing when to apply the power. Research has shown that the most effective and economical way to ride a time trial is at a steady power output, keeping your watts within +/- 2% of the target figure. Sprinting uphill at a high power output and expecting to recover down the other side is very uneconomical in terms of both energy cost and power-to-speed conversion. It's much better to ease off a bit on the climb and work harder on the faster, flatter sections where you'll gain more speed for your watts.

Aerodynamics and other drag forces need to be minimised but not at the expense of power. Too many riders try to ride in low and/or extreme positions and end up losing power at a rate far greater than any aerodynamic gain. Converting watts into speed is the key.

If you can accurately measure power output on the road, you can assess the effect of changes to equipment, position and riding style on your power, heart rate and speed. You're aiming to get a higher speed at the same or lower energy cost (heart rate).

Finally, that watts per kg figure... The lighter you are, the less work you have to do to ride uphill. However, lose too much weight and you lose muscular strength, resulting in a loss of power. There's a fine balance between absolute power output and power-to-weight ratio and history tells us that, generally speaking, a "good big engine always beats a good little one".

So to produce more power, all you have to do is use bigger gears and pedal faster? If it were that simple we'd all be World Champions! Unfortunately, there's another factor that determines how much power you can produce on the bike: physical fitness. You need a strong heart and lungs, and good muscular endurance.

To increase your power you require improved physiological fitness so you can get more oxygen and fuel to your muscles and convert it into forceful muscular contractions. The question is, what's the best way of going about this?

One of the greatest misconceptions in bike training is that strength training and power training is the same thing. This possibly stems from the way in which many people associate power lifting with strong men. As a result, they assume bike-specific power training means riding in big gears with heavy weights on their bikes. Sure, this may make you stronger but it'll also make you slow. You don't see professional cyclists training with heavily laden panniers in their off-season. No, they search out warm climates so they can continue training by riding their lightweight race bikes at the same speeds and in the sort of conditions as they'll be experiencing in races.

Remember, the purpose of improving fitness is to produce more power for a given level of exertion; in other words, more watts for the same effort. Power on the bike involves speed. If you want to ride quicker on the bike leg you need to produce more watts at your race pace. The concept is the same whether you're racing a sprint-distance event or an Ironman: in order to improve you must increase the power at which you race.

Improving maximal power is not the main issue; it's sustainable race power that matters. A sprint or Olympic-distance triathlete needs to be able to sustain a high percentage of their maximal power, while an Ironman athlete needs to sustain a lower percentage of their maximal power but for a much longer period of time. Whatever that percentage is, your race power is the number that counts. And the bigger that number the better.

Unfortunately, there's no magic formula to increase that number. To achieve this you need to increase your power output in all zones from the bottom up. In physical terms, power = strength + speed. Strength, in this instance, relates to the maximum force a muscle can produce in one contraction. In weight-lifting terms, how much weight can be lifted once. Speed relates to the rate at which a muscle can contract; in other words, the reps per minute or, in cycling terms, the number of revolutions per minute (rpm).

The speed of muscle contraction depends on the load placed on it. In the case of cycling that means the rpm possible depends on the resistance or gearing.

Power is therefore the ability of a muscle to contract quickly even when a force is applied. And the more powerful a muscle is, the quicker it can contract - even when it's working under a bigger load.

Strength-based gym work might increase muscle mass and strength but won't improve your muscle contraction speed. In fact, it may have negative effects and, if it's done badly, might even increase the risk of injury. Your muscles need to contract at 80-plus times per min on the bike - don't try reproducing that on a squat machine. The best way to improve cycling power is on the bike, combining leg speed with leg strength.

Power up

There are three things to look at if you want to increase your power: your base fitness, your aerobic fitness and your race power.

Base fitness

Base fitness concerns your ability to cruise comfortably at a decent power output using fat as a primary fuel in order to conserve glycogen for harder efforts. Improving base fitness means riding in your base training zone and gradually increasing the speed and power that you can hold while remaining within the zone.

Many riders spend a lot of time doing long slow rides to improve their base fitness. But if the effort is too low the ride has no training benefit and becomes simply 'junk miles'. To benefit your base fitness the load must be sufficient to elicit a training effect without being so hard as to take you above the base zone. This means ensuring you're working moderately comfortably throughout your ride - too easy and it's wasted time; too hard and you're not 'hitting the right buttons'.

This is very difficult to gauge on perceived effort or heart rate alone but conversation level is a good guide. For base-level riding you must be able to chat - albeit short sentences rather than paragraphs.

Aerobic fitness

You need good power output at mid-range efforts alongside your output at base fitness levels. This is the critical training load for Ironman triathletes and should form a high percentage of their training.

Developing aerobic fitness will allow you to sustain a higher percentage of your maximal power for longer without undue fatigue - the key to a successful long-distance athlete. As with base training, it's important that the training remains within the desired zones for the training effects to be maximised.

Think about a typical moderately hard training ride: it's windy and the route is hilly. You work hard into the wind, grinding up the hills and then, thankfully, as the road direction turns you've got a tail wind and some downhill. It's time to relax and to recover, right?

Wrong. For better training effects - and remember triathlon is about economy of effort and paced riding - moderate your effort on the hills and into the headwind. Think about tucking your elbows and knees in - employing a smooth but strong pedalling action to keep your effort under control - and focus on your technique. Increase your cadence as you crest the hill, working back through the gears to increase your speed and keeping your effort level the same as on the hill itself. Use any tail winds for some speed-based efforts, pedalling in the big chainring.

The aim is to do the same amount of work on the easier sections as on the hard ones or, put another way, to keep your power output constant. Not only will this help improve your sustainable power, as you'll be riding at that level for longer, but it'll also improve your economy, as you won'thave over exerted yourself. What's more, your overall speed will have increased, for less total effort.

Race power

Short-distance racing (around 60mins or so) is typically conducted at 85% or more of maximal power, and improving the power at this point is key to a fast bike leg. Even in an Ironman event you'll benefit from top-end power-based training in order to reinforce your aerobic fitness and increase aerobic efficiency to sustain that high percentage power and resist fatigue.

Furthermore, when conducted on top of a strong aerobic base fitness, top-end training will provide good power gains relative to the time you spend training. Short, hard and fast interval sessions are key, plus fast-paced hill work. And yes, the focus must always be on speed.

Your base, aerobic and race power can all be improved with specific training sessions, as this table shows.






Power pacing

Power is useless if you don't know how to use it. Use too much too soon and you'll fade before the end. That's why pacing is the key to an optimum performance on the bike leg. Get it right and you'll be on for a good time; get it slightly wrong and you can start adding seconds, if not minutes, to your finish time. Get it totally wrong and there's no guarantee you'll even finish at all.

The best way to apply power is evenly throughout the entire ride. Work out the most power you can sustain for the entire distance and do your best to keep riding as close to that intensity as possible. Slip into a higher intensity level and you'll pay for it later on; hence the need to back off on hills rather than attack them. 

The key to a well-executed power pacing strategy is knowing what your sustainable power is, and while a power-measuring device is useful for this, you can work out a strategy without one.

Limits to your power

The reason pacing is so important is because your power is not unlimited. Therefore, the key to racing well is knowing when and how to apply it for the greatest effect. However, it's not just your fitness that limits your power supply. There are a number of factors that determine your power at lactate threshold and hence your performance in an endurance event.

These include:

Gender Men tend to have higher power outputs than women at the equivalent training effort simply because they have more muscle mass and their muscle fibres can produce greater contractile forces.

Age Power output tends to decline with age simply because muscle mass decreases and fibre type changes. Maintaining all-round physical fitness, however, will ensure that these natural declines are minimised.

Body mass Power comes from muscles - not just their size, but their ability to contract fast. Nevertheless, the bigger your muscles, the more forcefully they can contract. However, as muscles are heavy, any
improvements in absolute power need to more than compensate for increases in weight and size, which can result in aerodynamic losses.

Body type Ectomorphs (long, lean and skinny types) may produce less power in absolute terms than a strong, well-built stocky person (a mesomorph). However, power-to-weight ratio vastly favours the ectomorph as soon as there's a bit of uphill.

Untapped power

While the means to test and measure power as you ride are new, the power itself isn't. The best riders have always been the ones who could sustain the most power for the most time, and improving your power is ultimately what all training is geared towards.

Power - how many watts you can produce and how long you can sustain it - is the key determinate of your race performance. You can train more effectively and gain greater improvements by basing your workouts on power. It'll keep your training specific and individual, help you to plan ahead and ultimately enable you to perform better when race day arrives.

Dr Auriel Forrester is a former world masters cycling champion and now a full-time triathlon and cycling coach

 

 


Power myths

Adding weight improves power

Big doesn't necessarily mean better when you're on the saddle. In fact, increasing your bike's weight will increase drag and reduce your power-to-weight ratio, thereby making you slower. This is fine if you're training for a cycle-touring holiday but not what you're looking for if you want to increase race speed.

Longer cranks mean more power

Increasing crank length means more leverage, not more power. Longer cranks mean that your feet will have to travel further around larger diameter pedal revolutions and, as a result, you tend to end up pedalling more slowly and erratically. Power isn't related to crank length; it's determined by pedalling force and frequency. To increase power you need to increase both.

Riding uphill in a big gear will increase power

Not on its own, it won't. Over-gearing on a climb may improve your leg strength but it won't improve your leg speed (cadence). Furthermore, such riding is likely to instill poor riding technique. Ride uphill strongly but balance that with spinning fast downhill. After all, power = strength + speed.

Weight training improves cycling power

As far as endurance cycling is concerned, there's no scientific research to support the theory that weight training results in increased cycling power. Cycling requires your muscles to contract at a far greater rate (80-plus times per min) than any weight-training exercise will ever allow. Therefore the best way to improve cycling power is - yes, you guessed it - cycling

Sprint triathletes need to do more power training than Ironman athletes

Training to improve your power is training to improve your fitness. Ironman athletes do more hours of training. That means they'll spend more time improving their power - especially if they train effectively. Okay, so a sprint triathlete may race at a higher percentage of their maximum power, but Ironman athletes also need to be able to sustain a decent power output, and for a longer period of time. Both distances require specific and purposeful power-based training.

Power meters are too expensive

Not really. Reliable and scientifically proven power-measuring devices can cost less than a new frame or pair of race wheels. And these are no one-off time saving devices. Power packs deliver improvements in performance that are on-going.

 


 
 

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