Power Training for Mountain Bikers - Part 1

To climb faster you either need to get lighter or produce more power. On flatter ground, lots of power really rules the roost, but what is it and how do you get it?Power corrupts. Absolute power corrupts absolutely. It seems that cyclists are not immune from the attractiveness of power either—the not-too distant revelations with regard to Lance Armstrong being a topical case in point. Quite simply, the more of it we have, the faster we go and the more we want—it’s as simple as that. It seems that some people will do almost anything to get more power, because it’s fundamental to performance in cycling...

Thankfully, you can improve your ability to produce power through targeted training, without employing any banned substances! There are lots of ways that you can empower yourself to beat your mates and you may well leave them asking, ‘what’s he taking?’ At this point you can stand towering over them at the top of the climb with hands on hips and proudly declare, ‘I’m clean, be gone with you!’ Which could be quite ironic in the sport of mountain biking, as you may well be covered from head to toe in gunge.

What is Power?

In physics, power is the rate at which energy is transferred, used, or transformed. Power in cycling terms is defined by ‘watts’ which is joules per second or more simply, it’s the rate at which the work is being done. The power produced by a cyclist is a product of the torque (rotational force) that he or she produces multiplied by the angular velocity (pedal cadence). This means that two riders could produce the same power in two very different ways; either by pushing a big gear with high torque and low cadence or by spinning a smaller gear with low torque, but higher cadence.

All being equal, the resulting speed they’d achieve would be the same, but the physiological load on the human body would be very different in each case. If you own a power meter (there are various types out there including Powertap, SRM and Quark), you can experiment and you’ll quickly establish that the two scenarios above are born out. A power meter is a great educational tool sometimes, because it teaches you that it’s actually easier to produce an even, sustainable power output at a higher cadence than a lower one—and the computer doesn’t lie.

To fully understand power, you also need to learn about ‘energy systems’ which are the pathways through which the human body produces power. There are three of them; the phospho-creatine or PC system, the lactic acid or LA system and the aerobic system.

PC System - This system uses stored chemical energy to produce power and the rapid breaking down of creatine and phosphate to release energy. This means that it’s an anaerobic process (doesn’t require oxygen). The power produced via this system is extremely high but it runs out very rapidly; a bit like an explosive firework display where the organisers are on a tight budget! Training this system gives you more explosive short-term power, enabling you to sprint better or tackle short sharp climbs with greater speed. To give you an indication of its non-enduring nature though, the power is gone in 15 seconds!

LA System - This system rapidly converts carbohydrate (glucose) into energy without the need for oxygen (again this process is anaerobic), but the exhaust fumes from this kind of power production (lactic acid) poison the muscle by lowering pH. It’s the body’s ability to buffer lactic acid that’s the limiting factor in the usefulness of this system—the better the human body gets at buffering and removing lactic acid, the more power it can produce.

Aerobic System - This system burns carbohydrate, fat and oxygen and is an extremely efficient form of power production, but it is very slow to get going and doesn’t respond at all well to short-term energy demand. Peak power output from the aerobic system is also relatively low. The fact that this system utilises oxygen and is called ‘the aerobic system’ is probably a clue that this system is in fact not anaerobic, it’s aerobic.

Each of the three energy systems are trainable, so if you want to increase your power and how fast you are on a bike, understanding how to train them properly is vital.

Training the PC System

Of the three energy systems discussed, this is the least useful for mountain biking, but it is very easy and painless to develop. It does take a lot of time to train it properly as the sessions are long, but if you feel that you really lack explosive sprinting power over very short durations this is an important system to consider. Most mountain biking efforts tend to be a bit more sustained and hence the lactic acid and aerobic systems are more relevant. Still, a bit of extra explosive power never goes astray.

The secret to training this system is to find a little hill and mark a start and finish point—these need to be 10-15 seconds apart when you are pedalling flat out. After a warm-up, launch into your first sprint and towards the end of the effort, you should feel a fading in power, but no pain. You then need to cycle really gently for three to five minutes to allow the PC pools to reform before attempting your next effort. These intervals are performed at the highest of intensities, but with a very long recovery period. It’s important to note that cutting your recovery period short will reduce the effectiveness of this session, so don’t do it. Keeping the intervals short and rest period long is vital. If you don’t allow the PC pools to reform, you’ll miss the target and wind up working the lower power lactic acid system instead.

Here’s an example of a PC training session that you could do:

After a good warm-up, do eight 15-second sprints with three to five minutes’ recovery in between. As you progress, you could increase the number of repetitions up to 16. When coaching downhillers we often prescribe more than this to really overload the PC system.

In terms of supplementation, there’s a significant body of evidence supporting the use of creatine to develop more explosive power, but it does come with the handicap of weight gain—something that will hamper performance in endurance athletes, so we don’t recommend it to mountain bikers unless they’re downhillers.

Training the LA System

This system produces less raw power than the PC system, but it more sustainable. Unfortunately the by-product discussed earlier, lactic acid, makes this system less enduring than the aerobic system which has easily disposable waste products.

The mantra for training the lactic acid system is ‘no pain, no gain’ because training it properly hurts a lot. The more power you drive from this system, the more lactic acid you produce and the more intense the pain. Good things happen during this painful process though, because high levels of acid force the body to adapt and get better at tolerating it. So you’re aim during these sessions is to cause as much pain as possible and drive your body to adapt to produce buffers and pathways for lactic acid clearance.

Find a slightly longer hill this time as you’ll need to perform a one-minute interval. A really pure lactic acid interval session that isolates it from the aerobic and PC systems would go as follows:

After a solid warm-up, perform six hard one-minute efforts with two minutes of recovery between each. As you get stronger, you can progress the number of intervals up to 10 and then possibly 12. This is a very hard session, so start with only four intervals if you’ve never done anything like this before because you can feel a tad queasy after this one!

In terms of supplementation, there’s very good supporting evidence that bete-alanine has a beneficial effect on lactic acid buffering, so this could be worth considering once you’ve hit a plateau with your interval training.

Training the Aerobic System

This is where so many people go wrong. The aerobic system loves predictability and low intensity. As intensity increases during a long ride, the lactic acid system starts to help your aerobic system out, so your increased power comes from a combination of aerobic system and lactic acid system. This is fine, because it’s ultimately how you get your fastest rides (and highest power outputs). But from a training perspective, if you want to develop the aerobic system in isolation, the lactic acid system needs to be removed entirely from the equation.

The aerobic system doesn’t like sudden changes in power output simply because it takes a significant amount of time to adjust the oxygen levels in the muscles. If demand is suddenly increased, it’s a long distance from the lungs to the leg muscles and so the shortfall in power has to be bridged by the PC or lactic acid systems. Again, this takes the pressure off the aerobic system, which is the last thing you want to do when you’re trying to train it.

To train the aerobic system effectively, you need to keep your power output constant and steady for the whole of your training ride, and the rides need to be long to stimulate a proper training overload. So, if you have four hours free to go for a long base ride, you’ll get more benefit from keeping it slow and steady than you will from riding harder—this is the part that many people find hard to gasp about successful aerobic base training. However, if you ride too hard, the lactic acid system will kick in, which then inhibits aerobic metabolism and you’ll be targeting the wrong energy system.

The benefits of training the aerobic system properly have to be experienced to be believed. We often refer to it as ‘free power’ because it requires very little carbohydrate (it mostly burns fat) and once developed properly, your aerobic system scoots you along at a rate of knots for a very low effort level.

The only way to accurately establish your ‘aerobic zone’ is to undergo a physiological test in a laboratory setting, but the RPE (rating of perceived exertion) table offers a surprisingly accurate indicator. An RPE of three or four is how you should be ‘feeling’ during an aerobic ride. Incidentally, 10-11 is how you should be feeling on an interval session targeting the lactic acid system! When training the PC system we class the effort as N/A on the scale as those sessions don’t hurt.

To train your aerobic system properly you’ll need constant and steady intensity; soft pedal up the climbs and gear up as the gradient eases. Think ‘constant pressure on the pedals and constant cadence’ or ‘constant chain tension’ and you won’t go far wrong. Obviously a power meter makes this very easy achieve—if you’re lucky enough to own one!

Threshold Power

Finally there are training sessions that are aimed specifically at developing your anaerobic threshold or FTP (functional threshold power). These cross the two main energy systems – the aerobic and lactic acid systems – and develop your maximal sustainable power.

Isolating the energy systems as we’ve already discussed goes a long way towards helping your threshold power, but sessions that work both the aerobic and lactic acid systems hard and continuously will do an even better job. Threshold power helps you in time trials and lets you drop your mates up long, drawn out climbs. The perceived effort for these sessions tends to be around eight or nine and for the 20 minutes or so that these efforts last, you simply can’t ride any harder than this.

What’s significant (and through our consultancy we repeatedly find this) is that most people ride at what we call ‘mixed pace’ practically all of the time, because they don’t understand the benefits of targeting the different energy systems independently. The romance of cycling is well and truly lost if you don’t perform at least some of your riding at mixed pace, but hopefully this article has urged you to consider an alternative approach to training, especially if you’re a competitive type and want the best performances possible.

You’re probably wondering how you should string all these sessions together on a weekly/monthly basis now aren’t you? I am going to tell you, but you’re going to have to wait until the next issue of this magazine I’m afraid as we’ve run out of space!

For the time being though, have a play with the concepts that I’ve outlined and see how you get on.