Most people who get involved in the online fitness community soon learn to make fun of the commercial gym personal trainers who seemingly have everyone they train perched on a bright pink stability ball, tiny dumbbells overhead. Their obsession with core training leads them to fail completely with their clients, as they create no noticable results in body composition, strength or endurance.
Having said that, there does appear to be a real rationale for incorporating core training into many programmes, particularly for endurance running. Let’s take a look at a study that shows how core training can be helpful for marathon runners.
Marathon runners (photo by Julian Mason)
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What’s the study this time?
It’s called Does core strength training influence running kinetics, lower-extremity stability, and 5000-m performance in runners? by Sato and Mokha, Journal of Strength and Conditioning Research, 2009.
Don’t get too taken by the reference to 5km races. The runners used in the study aren’t well-described but I did find a reference to their training for marathons. So let’s assume they are marathon runners.
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Statement of the problem
I thought it interesting that the researchers chose to summarise the current problem of core training as follows:
“Core-related exercises such as Swiss ball training, balance training, weight training, and yoga have become popular physical activities even among general populations in recent years. Even though scientific studies have not shown any links to prove performance enhancement, core strength training is becoming common for all levels of athletes.”
I thought this might be considered a little harsh but I guess it depends on what you consider proof of performance enhancement and whether you consider getting injured an inhibitory factor to performance…
Anyway, as a result of their assessment of the problem, the researchers set out to ascertain whether a short-term core strength training programme would have any effect on 5km running performance.
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What they did
The researchers set carried out a six week training study on 28 recreational and competitive runners (10 men, 18 women) who had no injuries at the time of the study beginning. The subjects were randomly divided into two groups:
- Control (14 runners)
- Core strength training (14 runners)
After dividing the subjects into the two groups, the 5km performance and the core stability of each runner was assessed. The researchers eliminated subjects who already possessed a high level of stability.
How did they ascertain which runners had a high level of stability? They used the Sarhmann core stability test. Subjects who scored a level III or better score (out of levels I–V) were excluded. In the event, only one runner was excluded, which says something about runners in general, I think.
After initial testing, the subjects carried on with their normal marathon training. However, the core strength training group also completed additional workouts involving five core exercises four times a week, comprising:
- Abdominal crunch on a stability ball
- Back extension on a stability ball
- Supine opposite 1-arm/1-leg raise
- Hip raise on a stability ball
- Russian twist on a stability ball
The researchers noted that these are not considered to be challenging exercises by strength enthusiasts but the runners were not familiar with such exercises and therefore managed to obtain a significant training effect.
And then, after six weeks, all of the subjects ran another 5km race.
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What is the Sahrmann core stability test?
I thought you’d ask about that. The short answer is that it’s a leg lowering test (yes, non-geeks can move on to the next section now).
The long answer is that the Sahrmann assessment protocol is a test of strength, endurance and stability of the lumbar spine. It allows a health professional to estimate the relative core stability of an individual to other individuals on a scale from I to V.
To carry it out, the tester places a pressure sensor under the subject’s lumbar spine while they are lying on their back with their hips and knees bent, each at 90 degrees. Then, the subject extends one or both legs slightly, or fully, depending on the level of the test. If they can lower the leg or legs without tilting the pelvis, then the pressure reading will stay the same. If it moves, the pelvis has tilted.
Lowering both legs to 12cm off the ground and bringing them back again would be a level V.
For more details, check out Core Training: Stabilising the Confusion, by Faries and Greenwood, Strength and Conditioning Journal, 2007 (online here).
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So what happened?
Since both groups were in training, you would expect them both to improve their 5km times over the six-week period. However, the control group improved just 17s and the core strength training group improved 47s. In both cases, the groups were running sub-30-minute 5km races.
So on a rudimentary measure, a decent club runner could deduct 30s from their time by doing some basic core training.
What can I say? Break out that stability ball!
