Saturday, June 03, 2006

DOWNHILL RUNNING

DOWNHILL RUNNING by John Harding

Mk Climbathon2climbathon03
Most distance runners shy away from hard downhill running, both in training and racing, because of fear of soreness and injury. In the Lore of Running by Dr Tim Noakes, there is a lengthy discussion of the medical and physiological research literature about muscle soreness and its various causes. The bad news is that fear of soreness is well founded for the runner untrained for downhill running. The good news is that not only can the possibility of ill effects from hard downhill running in cross country, mountain running and road races be minimised by appropriate training, but such training can greatly improve performance.

In the Lore of Running, Tim Noakes says that soreness after unaccustomed or particularly severe exercise is not due to an accumulation of lactic acid in the muscles, as many people have argued in the past, but is most likely due to damage of the muscle cells, 'in particular the connective (supporting) tissue as well as the contractile proteins'. The most muscle damage occurs with hard downhill running because of the eccentric contractions that occur during downhill running. Noakes explains that when an unloaded muscle contracts, it always shortens, and this is called a concentric contraction. In contrast, when a force applied to the musle exceeds the force that the muscle can produce during contraction, then the muscle length increases, and is called an eccentric contraction. In downhill running, these contractions occur in the quadriceps muscles (upper front of the leg) when the forces through these muscles become very large, particularly as the foot lands on the ground, and can be as much as three times the body weight. Noakes says the initial contraction of the quadriceps is not quite strong enough to overcome this force, so that the muscle is stretched in an eccentric contraction for a brief instant every time each foot hits the ground. Muscles are not designed to repeatedly experience eccentric contractions, and so running long downhills hard makes the muscles susceptible to muscle fibre damage, creating severe soreness.

Firstly, sprinters and middle distance runners have found that downhill running on a grass slope of 150 to 300 metres enables them to turn their legs over more quickly, an excellent form of exercising the fast twitch muscle fibres. A month or so of one or two downhill workouts a week on grass can produce a significant pick-up in leg speed and an improvement in running efficiency.

Secondly, training offers the opportunity to develop and improve technique. Running action is all important in achieving both downhill running efficiency and minimisation of the potential muscle fibre damage. There is a natural tendency by many runners to lean backwards and put on the breaks on a steeper slope. This is the worst thing to do as it increases the impact, jarring the body from the heels right through to the torso, creating stiffness and soreness in the quads, buttocks, hip flexors and lower back. Good technique involves leaning forward to get the body vertical to the ground, relaxing instead of tensing the legs and the arms, using the arms actively for balance, and using gravity to assist. To check up on your technique, the ideal is to get someone to take some video footage of you running fast downhill in a few different race situations, from the moderate downhill to the steep, from grass to fire trail. From seeing yourself in action, you should be able to work out for yourself areas you can work on to improve your technique, from arm movement to leaning of the torso to foot-plant, to stride length.

Thirdly, training allows testing to occur of footwear options for race day. In cross country, road and mountain running, footwear that grips the ground firmly on the downhill!

Fourthly, psychological preparation for downhill racing is very important. The best form of preparation is to actually practise downhill surges over the course to be used for the race, as this allows refinement of technique over different slopes and surfaces, testing of maximum speed at critical sections, and positive self-imagery to be built up.

Fifthly, the great American runner Bill Rodgers once said that in a hilly race the best place to attack is coming off the top of a hill. Psychologically the other runners are probably looking for a breather when they reach the top of a hill. If you relax on the uphill and then accelerate coming over the top, you have a splendid opportunity to catch other competitors by surprise, particularly if your running armoury includes good downhill technique.

Finally, there is what I call 'the little kids' benefit of downhill training. A favourite past time of my three children when they go to a park or a forest is to go the top of a small grass or other hill, yell, 'Yippee (or something similar)', and run to the bottom. There is something exhilarating in just letting yourself go, and running fast downhill with the wind in your hair and the terrain rushing by.


How best then to do downhill training?
My personal preference for technique training is soft dirt trails or short, firm grass, with the length of the repetitions dependent on the timing of the training cycle. I will explain this further. The research by Morgan and Proske suggests that year round weekly practice of downhill running is desirable, and some downhill striding out as part of a weekly long run on a hilly course would achieve this. However the best time to work on maximising downhill speed is the last six weeks before the major race being targeted. Start much earlier than that and you risk peaking too soon.

Initial workouts should desirably be downhill bursts over short distances of the order of 50 to 80 metres and not at full speed in order to provide transitional adaptation to eccentric contractions over three or four workouts. If the target race involves long downhills then the distance of the downhill burst can be extended up to 200 to 400 metres to practise technique, particularly if the training surface is soft and impact-absorbing. If the race course is over a harder surface such as fire trails, judgement has to be used about the length of the repetition. The goal is training and adaptation, not destruction and injury, particularly during the last month or so before a major race.

2 comments:

Karen in Calgary said...

This is GREAT STUFF!

Lots of hope for folks who are afraid of injury, and great technical training info. You even included what I call the "YaHOO factor".

I'll be referring to this post soon - good job.

Anonymous said...

That's a great story. Waiting for more. » »

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