 |
| Well hello there. |
Anyhow, the obviously, the reason I bring this up is that I happened upon an article while reading another article. (If you must know, the other article was on this topic: RunBlogger)
Effects of a Sand Running Surface on the Kinematics of Sprinting at Maximum Velocity by Alcaraz, P.E., Palao, J.M., Elvira, J.L.L., and Linthorne, N.P., Biology of Sport, Vol 28, No. 2, 95-100.
The authors wanted to look at what effect sprinting in sand had on a sprinter's form. They tested this by having sprinters sprint in the sand (stunning!). They ran two sessions, one on the track and one in the sand. After a specific warm-up, the did multiple sprints with complete rest in between. They were 30 metres sprints with a flying start, allowing 20 metres to hit speed. And, if you must know, the sand they tested on had an average diameter of about 0.25mm with a densite of about 1530 kg/m^3. Important stuff, people.
More importantly, the authors used high speed cameras to record and subsequently analyze the athlete's kinematics. The camera was placed about the 20 metre mark of the 30 metre sprint, perpendicular to the direction of running. They used elaborate biomechanical analysis software to create segments and landmarks on the body to blah blah blah science that's not really important. What is important is that the kinematic variables were centred around the instances of the runner's stride, the touchdown, mid-stance, take-off. Touchdown is obvious, mid-stance is when the athlete's centre of mass is directly over the toe, and take-off is the first instance of the foot being no longer in contact with the ground.
Results
Unsurprisingly, the athletes were slower in the sand than on the track, by 15.8 percent in men and 12.4% in women. What was the cause of the slower times? It was determined that their stride frequency stayed the same, but their stride length was shorter. So, there is a simple first conclusion, soft surfaces slow us down because every stride is less effective than on firm surfaces. The soft surface dissipates more of the energy and increases the amount of time the runner is in contact with the ground. Not exactly a revelation.
What's more relevant, of course, is how running on softer surfaces affects a runner's biomechanics. There were significant changes in the joint angles of the trunk and lower limbs. Essentially, the runners tended to, as the authors called it " 'sit' during the ground contact phase, with a lower centre of mass and a greater forward lean in the trunk".
 |
| Fig. 2 from the article - Dashed line is on the track, solid line is on sand |
With the hips set further back, the centre of mass is lowered, and their centre of balance is moved further back. If you've ever seen the vertical path of an inefficient runner's centre of mass, you'll notice that it spends an exceeding amount of time going up and down while moving forward. A more efficient runner will see significantly less vertical motion in that centre of mass. The same applies here, the bio-mechanical change of running in sand means there is more vertical motion in the athlete's centre of mass. Realistically, this is wasted motion, since going up and down really doesn't make you move any faster horizontally.
As the authors note, "elite sprinters run in a more upright position than good sprinters", and generally the same applies to distance running. Its all about maximizing horizontal motion, and generally decreasing the amount of unwanted vertical motion. Ultimately, the authors concluded that there is potential for sprint training in sand to be detrimental to an elite sprinter's form, because they may make technique adaptations in the sand that are inefficient on the track. However, that conclusion is not overly relevant to us....
So, how does this apply to orienteering?
Actually, I think this is relevant for a lot of reasons. And as I thought of them, I didn't write them down, and no longer remember.
What's most relevant to orienteering is the impact on form while running in soft conditions. If orienteers were always on nice Mondo surfaces and turning left occasionally, this wouldn't be as relevant. However, softer conditions are par for the course. How often in the forest do you get to run on pristinely firm surfaces? Almost never. I think this raises two questions (at least) related to orienteering that are relevant to performance:
1) Should we train ourselves to maintain proper form through the softer conditions, OR should we train to be stronger when our form is weaker?
I guess ultimately it comes back to specificity. If those sprinters spent all their time sprinting the sand, eventually they wouldn't be great sprinters on the track, but they'd probably kill it in the sand. What would be useful in that study is to do it more long term: if those athletes continued to run in the sand, would they get strong enough to re-align their form to be more efficient again? Clearly, no elite athletes would be willing to stake their career on such an experiment.
Nevertheless, orienteers will be guaranteed to experience all forms of terrain, from rock hard to super soft. An orienteer should most certainly take a careful look at their own running form on firm conditions and make an effort to ensure their form is efficient as possible. The best way to prevent your form from breaking down in less-than-ideal conditions is to start with a really strong base.
Second, and this goes back to the anecdote I mentioned in an early post, on the importance of leg strength and strength endurance. The quote noted that the Swede made an effort to work on explosive leg strength because he was able to lengthen his stride. As we have learned about, stride length is the primary cause in the reduction of horizontal velocity. If you are able to get more force out of every toe-off, you are not only going further every stride, but you also have the ability to reduce your stride rate and potentially save some energy.
Third, and as always, the importance of core strength, and in this instance, hip strength. The forward lean of the trunk in the above figure can be reduced by improving the strength of the muscles in the back (like the erector spinae), or the gluteus maximus. Likewise, those always stubborn hip flexors play a vital role in being able to pick up ones foot, drive the leg through, keep that butt from sitting backwards, and ultimately keep the centre of gravity from moving backwards and downwards.
 |
| Really, really ridiculously good looking. Running. |
In short, the answer to my initial question, is the former. One focus on having very good form, and then emphasize have the strength to maintain close to ideal form in softer conditions as well. The best way to do that? think about maintaining good form while running in softer conditions. Feel the differences in your stride. Note where you feel your weight has shifted, where angled feel different. Video yourself doing it. Compare them. No one is a bad runner, but we can all become better runners.
All orienteers will run a path if there is a path to take, that is a given. But how often do you think about where you're running while on the path? What about urban sprint? If you're running a long straight away and have the choice between surfaces? Do you think about it then?
As this article has shown there could be as much as a 15% performance difference in your choice of condition to run on. Granted, that's going from almost ideal, to almost worse, but there is a decisive difference.
 |
| Choose a route from 12-13, one is shorter, but which one might be faster? |
So, there you go. I must admit, I seem to be reverting back to the same main points, maintenance of form through a strong core is essential to everything. I will make an effort of diversifying. You are also welcome to come up with your own conclusion. Your are undoubtably smarter than I.
There is also one more place where its good maintain good sprinting form. Just in case you need to run away, or maybe I'll find a real job and start doing this:
