Running Economy and Age – flexibility and strength factors

This is the third (and last) discussion about some research that came out this month in the Journal of Strength and Conditioning Research titled, “Aging and Factors Related to Running Economy”. While the information I’m going to discuss here is important as a stand alone discussion, I would recommend that you also read those other two discussions:

Part 1 – Are you too old to have good running economy? … summary, no you are not too old, as age was not a significant factor in the measured running economies at the chosen velocities.

Part 2 – Running Economy and Age – the other factors, body weight, experience and lactate… summary, body weight and experience (relative ability) play a bigger role in running economy than age, while changes in velocities at lactate threshold better account for performance differences.

You can find the abstract to the research article – here

Now to discuss the strength and flexibility factors:

One of the key hypotheses of this research article is that the running economies of the subjects would change with age. I imagine that part of their assumption for that hypothesis is that factors that lead to changes in running economy often change with age.

What might some of those factor be: muscle strength, muscle endurance, flexibility, power and stride rates.

One reason, I believe, that this research found that running economies didn’t change with age is because these subject were more similar than they were different. I discussed in the last write up about how the body weights and body fat %’s were similar among all three age cohorts.

When looking at various strength measurements, we find that all age groups are similar again. For example, when testing for a 1 RM (repetition maximum) on the leg press, all three age cohorts were found to be similar. Now keep in mind, the average ages for the groups were:

young = 27.6
masters = 50.9
old = 61.0

Therefore we have either some fairly special athletes that have aged well or some overly weak young runners. Due to the fact that these runners were all high achievers (1st, 2nd or 3rd place) I am assuming that the old group aged well.

Here are the actual numbers for their 1RM:

young = 132.7kg (+/- 33.9)
master = 126.9kg (+/- 30.2)
old = 114.4kg (+/- 14.2)

When looking at the lower body muscle endurance test, we find an even more remarkable outcome. To test this the subjects were asked to lift 50% of their 1RM at a cadence of 30 lifts/min. When looking at the numbers for this test, we actually see the performance improved with age:

young = 99.2 lifts (+/- 20.8)
masters = 105.4 lifts (+/- 22.6)
old = 112.3 lifts (+/- 31.4)

Again, there was no statistically significant difference among the groups – which again proves that despite age, the runners may have more in common than they have different.

The upper body strength tests did show some significant differences as the old group was significantly weaker than the masters and young groups in the upper body 1RM. Although, the upper body endurance tests showed similar results.

These results reinforce the concept that strength training can be beneficial to your running. This is especially true as a runner ages. Including strength training that, in the minimum helps maintain strength, will benefit the aging runner.

What about flexibility and step frequency?

Two other variables that were measured were flexibility and step frequency. The flexibility measurement was done by using a sit and reach test, measuring low back and hamstring range of motion. There were significant difference in those range of motion scores between the old group and the other two groups (young and masters).

There were no differences among the three groups in the measured step frequency.

How these two may work together, mechanically, to alter running velocity.

When you look at running velocity (speed) we have a couple variables to account for: stride length and stride rate. If we know that stride rates are equal, yet running speeds decrease than we begin to make the biomechanic assumption that the runners stride length has decreased.

The flexibility of the runner factors into this discussion because when a runner’s flexibility changes it can alter their running mechanics. Specifically if a runner’s flexibility decreases it can decrease the stride length that a runner may be able to achieve.

One other variable that the researchers measured was jumping power. To do this they measured the runners vertical jump and used that along with their body weight to calculate power. In this testing, they found that while there were no differences between the young and masters group, the old group had a decreased jumping power. This decreased power could also be evidence that stride length is decreasing with the old group, again accounting for some of the lost velocity.

Final conclusions:

When you look back at all three of my discussions on this research, we find some important take away messages:

1. Age does not have to play a factor in decreased run economy.

2. Maintaining two things will play a factor in this: body weight and lower body strength and muscle endurance.

3. Running experience matters, therefore running consistently and over many years will help you personally achieve your most economical running pattern.

4. Running performance is best assessed by run performance, but if you want to predict how a runner might be able to do, use a measurement such as velocity at lactate threshold and not some biomechanical analysis.

5. Flexibility and lower body power are things a runner should at least pay attention to.

I hope that you’ve been able to learn something around this discussion on running economy and aging, please feel free to join the discussion by leaving a comment here or contacting me with any questions.