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‘Tempo’ sessions for a race walker are key sessions in enabling them to improve race speed. Why? Settle down, and find out below . . .
Lactic Acid and Race Walking
When we race over anything up to about 20km, the main thing that limits our speed (assuming our technique is good enough to allow us to go at speed) is the accumulation of lactic acid in the blood. Lactic acid causes pain and discomfort. It also reduces the efficiency with which our muscles can turn fuel and oxygen into power, and it interferes with the nervous system and with it the quality of the control that we have over our limbs and muscles. Hence high acidity can result in deteriorating technique and red cards. Lactic acid is not all bad – if the body is used to it, it can be burnt in the muscles as a supplementary fuel. But as a general principle, we need to develop our bodies’ ability to tolerate high levels of lactic acid. We need to maximise our bodies’ ability to clear lactate out of the working muscles back to the liver, where it can be dealt with most effectively by the body.
Getting Better at Dealing with Lactic Acid
As ever in athletic training, we do this by giving the body a challenge – moving it outside its comfort zone. Then we leave the body to adapt itself, as it always does, to function better the next time it has the challenge. The challenge we give it, is to walk at something faster than a steady pace for a reasonably extended period of time.
Not Too Slow
We don’t want to walk too slowly – our bodies are used to clearing small to medium quantities of lactic acid out of our blood all the time. Walking at an easy or steady pace – a pace at which you are not breathing hard and can easily hold a conversation – keeps the level of lactic acid down to one that the body can easily deal with. Training like this for part of the time can produce some benefits, but it won’t improve your lactate tolerance.
Not Too Fast
Nor do you want to go too fast – if you go above a certain speed, you end up producing lactic acid faster than the body can cope with it, and after a while there is just too much for you to be able to continue. You can’t breathe fast enough, everything starts hurting, your technique falls to pieces, and you have to stop. Again, training like this can produce benefits – this is what happens when we do reps and intervals over 200m, 800m and other distances, when the time for each effort is about 5 minutes or less. But again, this is not the best form of training to improve lactate tolerance as the body does not have to get used to continuously having a high level of lactic acid in the blood.
The ‘Goldilocks’ Speed
Ideally you want to do ‘tempo’ training at the speed at which your body struggles to clear lactate out of the bloodstream but just manages it. Normally this is about your 10k race speed. In this zone you are working comfortably hard, but you will be able to continue at that pace for 45 minutes or so, so the body gets to be ‘educated’ that it will have to learn to deal with a higher level of lactic acid, and not just wait for it to stop in a few minutes time (as it can when we are doing intervals). The heart gets better at pumping the lactate-laden blood out of your muscles and round to the liver. The liver gets better at processing lactate in the blood, turning it into carbon dioxide and water that get breathed out of your lungs, and turning some of it back into glycogen that can be used again as fuel. As your body gets used to working hard with high levels of lactate available, it also develops the ability to use lactate directly as a fuel in the muscles, without needing to be recycled via the liver. The nervous system gets used to functioning correctly despite higher levels of acidity in the environment it is working in. You get more used to psychologically tolerating the discomfort of high levels of acidity. All in all you develop ‘speed endurance’ – the ability, not just to go fast, but to go fast for an extended period of time.
So I have to get the speed exactly right?
Not necessarily. If you were a professional athlete you would get tested regularly, and you would be told exactly the correct speed to do your tempo work to get maximum benefit. This will be a speed at which your blood contains about 4 millimoles of lactate, per litre, and if you go any faster than this, the number of millimoles per litre starts to climb into the stratosphere. Now for most of us who do not have specialist measuring equipment, we can’t know exactly what this speed is. But it is also, typically, it is the speed at which our heart rate is 90% of its maximum, and it is also approximately our 10k race pace. If we are going too fast, and our lactate level is climbing into the stratosphere, we get to know about it soon enough. We have a choice – either slow down, or stop completely, and the correct option is to slow down to a pace you can sustain. If we are going too slow, if we are honest with ourselves we can recognise that we could, if we wanted, go faster, and keep the pace going for 40-45 minutes or more, we should speed up. A heart rate monitor will help, but for most of us, you don’t have to get to exactly the correct pace, and getting close to it brings most of the benefits of tempo work. A 60-minute ‘tempo’ session, for example, may not be at a true ‘tempo’ pace, but normally will still be very beneficial training.
How often can I do tempo work ?
As a general principle, the faster you do your tempo work, the better the training adaptation. Runners generally need to be careful about how fast and how often they do tempo runs, because for runners, a lot of tempo work means a lot of sessions that produce impact on the joints and if they do them too often, with insufficient time to recover, they get tendon and muscle strains and eventually, overuse injuries. Race walking as we know is low-impact, so tempo training causes less tissue damage, and shorter recoveries are required between tempo sessions than runners would need. For young and senior race walkers, tempo work every day would be possible – which it wouldn’t be for runners. For masters, tempo work every 2 days can be considered.
How can we do tempo work?
In the Tilsley Park training group, at present (end of 2014) we do tempo work in two different sessions. We do our ‘laps’ sessions on a 2.5km almost-traffic-free circuit, so our sessions of 2, 3 or 4 laps, with a warmup and cooldown, can be effective tempo sessions. (The 4-lap sessions will be a bit slower than 10k pace, but not much, so that we can keep a relatively high level of lactate but keep it going for longer.) Also, in the distance/fartlek sessions of 10k or more, we want if possible to do as much as possible of the session at a 10k pace. Of course it’s not possible to do the whole session at the correct pace – unlike on the ‘laps’ sessions, we have to stop or slow down for road crossings, negotiate some busy pavements, loop back to rejoin the training group, and so on. But the more of these sessions that we do at ‘tempo’ pace, the more like a ‘tempo’ session it will become, and the more of the benefits we will get – while still being able to share the training session with people that may have different objectives or whose ‘tempo’ pace may be different from ours. There are other ways, too, of getting in tempo work – e.g. for 20k walkers, long intervals of 2k each done at 10k pace can be a very valuable training session.
Tempo work is the real bread-and-butter of race walk training – once your technique is good enough, and your stamina is good enough to keep up the distance, then most race walkers will spend most of their sessions, most of the year, doing tempo work. And unlike for runners, it will be good for them. Many runners train this way too, but see above – sadly, for many of them it brings with it too much pounding of the joints, and many will succumb to overuse injuries.
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