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Thursday, February 12, 2009

Exercise and aging Part 2

Exercise and aging: Growing old gracefully, with speed!

Yesterday we began a series on exercise and aging by looking at the world records across the age categories. To remind you, here's the graph minus the notes from yesterday:

I've indicated the records for 30 years, 50 years and 72 years, just to illustrate the main point of today's post. You can work out who holds the 30-year old record if you want (hint: He is one of only four people to break his own world record, and he ran for a country not of his birth). The 50-year old is Titus Mamabolo (a South African - our only record holder these days), and the 72-year old is Ed Whitlock of yesterday's post.

But the point that I alluded to yesterday is that there is a flaw in using this graph (or the relationship) to project what your own time will be at age Y based on your time aged X.

That's because the graph you see above is made up of perhaps 50 different runners, and each one has an entirely different trend in performance over the years. The individual running 2:05:38 will NOT be running 2:19:29 at 50, and will NOT run 2:59 at the age of 72. We know this because it hasn't happened on a single occasion in all the age-group records that one individual holds records more than 9 years apart. Ed Whitlock, who we introduced yesterday, and will feature again the future, is the holder of the most records - he owns 8 age-records, all in a batch.

A window of performance? Depends on the performance...

This seems to suggest that individuals have a narrow "window" during which they are able to excel. Bear in mind that "excel" in this case means running faster than any person in history! That's a tough bar to set, so I must make the allowance that the "window" becomes much longer when you start to lower the performance level slightly. That is, someone who is running at say 80% of the world record pace can probably much more accurately work out how their performances should change over time (which is why those calculators that predict your age-equivalent times do have some merit)

Of course, people tend to over-value those equations and formulas that work out what your time at the age of say 60 would be equivalent to if you were 30. While interesting, such predictions can't really be used as "instructive" or to judge your current performance, because you're on your own journey, and the changes over time can't really be accounted for unless you do a massive study that looks at say 500 individuals over the course of 60 years and plots the average decay in performance (and, to the best of my knowledge, that hasn't been done).

The reasons for the decline - age physiology

So now we get to the reasons for the decline. And this is relatively well-known physiology, which I promised yesterday that I'd avoid spending too much time on. However, it's important to understand as we move forward, because the next step will be too look at "Chronological Age vs. Running Age", and so we need to understand Chronological age.

So what can you expect as you get older? (That feels very morbid as I type it..., sorry)

Aging affects numerous physiological systems, including the neuromuscular, hormonal, respiratory, cardiovascular and metabolic systems.

Lean muscle mass and age

Perhaps the most widely known and significant changes that occur with aging are those that affect the muscle, and happen in part because the levels of hormones like testosterone and growth hormone fall over the years. Testosterone is the one everyone knows about because dopers use it so often, and as any body-builder will tell you, is anabolic (as opposed to catabolic), because it builds up tissues in response to stress, and is responsible for muscle growth and development after training.

Testosterone levels peak during adolescence and early adulthood, but somewhere between 30 and 40 years of age, begin to decline progressively. As a result, lean muscle mass declines by as much as 30% between 25 (when peak muscle mass occurs) and 70 years of age. This reduction involves decreases in the total number of muscle fibers and a decrease in the size of the fibers. At the same time, oxidative damage causes further reductions in muscle mass, as does a decline in the number of motor neurons that provide neural “nourishment” to the muscle fibers.

The net effect of the reduction in muscle mass is a loss of muscle strength – as much as 2% per year, so that by the age of 70, strength is reduced by up to 40%, though this depends on the individual and also their activity levels. Training helps prevent these reductions, which is good news, and is the part of the equation that you can control.

One of the more obvious, and upsetting consequences of this change is that your metabolic rate slows down, and so you start to gain weight (fat mass, that is). The common misperception that "muscle turns into fat" is actually the storage of fat that is partly caused by a loss of muscle thanks to aging. It's not that muscle is converted to fat, but rather that fat now tends to be deposited much more easily. If you don't adjust your diet, "middle age spread" is the result!

Injury and adaptation

One of the more frustrating aspects of aging (and the reason you've probably been the butt of some jokes from friends) is that your ability to recover from training is reduced. Pretty much all "moving parts" don't quite recover from sessions the day before, and your body’s ability to adapt to the stress of training is also reduced. You can no longer repair damage by laying down stronger muscle fibers in response to training. One of the big benefits of taking testosterone is that it aids recovery, allowing harder training. Aging is effectively "reverse doping", since testosterone is reduced, and training can't be done to the same level as before. One of the first things people will notice is that they wake up stiff and commonly jokingly say "I must be getting old". Exactly!

Other hormonal changes further contribute to this adaptation barrier – the production of growth hormone decreases steadily from the age of 10, just after puberty, which has much the same effect as the fall in testosterone, as well as some other effects on metabolism. Growth hormone has even been called the “anti-aging” hormone, a popular choice among the Hollywood elite to retain their celebrity looks! We'll return to this hormone again in the future...(thanks to Peter for his input on that one)

Other aging effects

There is also a decrease in the number of capillaries to each muscle fiber, which means that valuable energy and oxygen delivery to muscles is compromised. Stroke volume (the amount pumped per contraction) and heart rate also fall over time, meaning less blood can be pumped to the body as cardiac output falls. Respiratory muscles get weaker, and the resistance in the airways rises, which makes breathing harder work. The ability to get valuable oxygen out of the air into the blood and to the muscles is reduced, not a great outcome for a marathon runners! It doesn't take a degree in exercise physiology to appreciate how these changes in the heart and lungs would make running or any other endurance activity much more difficult.

Inside the muscle, proteins that are important to assist with metabolism are not produced in the same quantities – you therefore become less effective at producing ATP to power muscle contraction. The muscle’s capacity to store and release energy changes with age – less glucose and glycogen can be stored, and the muscle becomes less sensitive to hormones that normally drive metabolism, like adrenaline.

Changes in women - even more pronounced

In women, hormonal changes have even more dramatic effects – menopause and the associated hormonal changes are responsible for many effects, perhaps the most relevant for running being a decrease in bone mineral density that predisposes women to the development of osteopenia, which is a precursor to the more serious osteoporosis, where the risk of fractures is greatly increased.

Here, the excellent news is that running (and other exercise), because it is a weight-bearing exercise, is one of the most effective means of preventing osteoporosis, because it helps elevate the bone mineral density at a young age so that the inevitable age-induced decline does not have potentially disastrous consequences.

The same goes for all the other changes - the body ages, this is as inevitable as death and taxes (as the saying goes). However, regular exercise slows down the rate of decline in many of these systems, or at least reduces the impact of the change. The result is that regardless of what you've read in this post, and the fact that you may be bemoaning lost youth (don't worry, I am too!), if you continue to exercise now, then you'll reap the benefits, in spite of your natural battle against father time!

Chronological age vs running age

Well done if you've managed to read this far. This was a "textbook" physiology post, not my favourite kind, but hopefully I've skimmed through all the important systems and how the years affect them. If you're a scholar or student who just happens to be doing an assignment on this topic, then you're in luck (Please feel free to donate to us through our PayPal link! And don't forget to reference everything you say!)

However, this is all a precursor to the more juicy and exciting discussion to come, probably next week. That's when we'll start looking at the impact of many years of running as compared to many years of living. There is evidence that running age is just as important as chronological age in determining running performance, and that the two interact to properly explain what you will have experienced. And the notion of a "window" of opportunity seems to be borne out.

So let's tackle that next week, when we're all three days older. Hope this was instructive and not too morbid!



Thomas said...

As a 39-year old who has been running for just under 5 years, this is a topic very close to my heart. I'm still improving my times, but I do wonder how long this will last, and if I can break the 3-hrs marathon before slowing down due to age.

I'm very much looking forward to the next instalment.

Anonymous said...

More than morbid, it was extreamly depressing. Hoping for some good news soon!

Anonymous said...

Very, very interesting article (as usual), especially for a fifty year old like me.

At the risk, as always, of being pedantic, I think it's worth emphasising that, as one ages, one's basal metabolic rate slows down, but that one's non-resting metabolic rate ... - well, that's an interesting one, don't you think? It seems plausible to predict that as one ages, one also becomes less mechanically efficient. If that's the case, then, as one ages, one can expect one's non-resting metabolic rate to increase for the same work output.

To give an example: if I make the effort to run at age fifty the same 20km course, up hill and downhill, at the same average speed at which I used to run it at thirty, it seems plausible to predict that I will have used more energy by the run's end to do this at age fifty than when I was thirty... Don't you agree, guys?

For me, the maxim remains the same: fight the good fight with all one's might, run every race as fast as one can, for what a shame it is to grow old, without ever knowing the strength and vigour of which one's body is capable.

Anonymous said...

Great series. It's a shame you're focusing on the marathon, though, because there is so much variation of course, climate and weather that it is difficult to compare performances.

How about looking at the times of runners over track distances? Runners who, for whatever reason, have been able to keep the desire to train with intensity that they had when they were younger?

What would also be interesting is to look at the progression of world age records. Are they getting faster, like "normal" records, year after year? And what does that then then suggest?

The right kind of training - both to preserve muscle mass and in terms of intensity, not only slows down the effect of aging, but can temporarily suspend it. Especially if nutritional support and (legal) hormone replacement is incorporated.

As Oliver said, in a comment to part 1, the most important factor in this debate is motivation: the willingness to train with intensity.

I believe that's the main reason why most runners, as they get older, go longer and turn to the marathon or ultra-distance races. It's not a physical thing, it's that mentially/emotionally they just can't face another set of 10x400.

If you look at the record of Derek Turnbull "The Fastest Old Man in the World", you can see times that defy prediction (and aging).
DT was the first over-60 under 2:40 with his 2:38:46 in Adelaide in 1987. In 1990 he ran 2:41 in New York, but in 1992, then over 65, he ran 2:41 in London. So much for age-related deterioration.

Derek Turnbull's mile times do show a steady slowing but there were occasional inexplicable blips, when his health, desire and training all came together. For example he ran a mile in 5:05 aged 62, then a mile in 4:56 aged 65. Remarkable, huh?

Also check out the great Nolan Shaheed - world record 1:58.6 800m at 50, 2:03.8 at 55. 5k national records 15:00 in 1994, 15:36 in 2001.

Ross Tucker and Jonathan Dugas said...

HI everyone

Thanks for the comments. To respond in turn to each?


THanks for the interest. Impossible to say when you'll "peak". In the next part of the series, I'll cover this aspect, because there is some evidence around when athletes "peak" and have their best performances. However, and this is what I was at pains to point out in post 1, it won't necessarily apply to YOU. I can tell you that "on average, the peak happens after 3 years of marathon running", but you're not the perfect average! So don't let this science dictate your future prospects!

To Derek:

Sorry...! Good news is that exercise training now can slow that decline right down, and even stop it! How's that?!

To colenso:

Fair point, I should have stated basal metabolic rate.

I'm not 100% sure about metabolic rate during exercise. There is another line of thought that older runners get MORE efficient. I suspect there's no "rule" - some will improve, others get worse, so I'm not sure how it impacts on metabolic rate and energy use during exercise. Not even sure that has been studied.

To Simon

I'll definitely try to find some research on track. The reason we've focused on the marathon is because that's the information I'm familiar with. Amby has given us a lead (in part 1's comments) that will hopefully open up other events and avenues, so I'll certainly try to apply this to those sports.

Interesting about whether the records are progressing. I'm not sure how one would analyse that? Again, I have limited access to information, and limited time to expand that access! However, I think they're probably improving. A big part of it is that many of the older records (as in older runners, that is) are European athletes, and as the best Africans age, we might start to see some of those 50, 60 year records fall, just as the 25 year records have fallen to this new group. In that case, performance is a function of "opportunity" and access to racing.

But that's speculative, I'm not sure. Also, I guess things like better diets, healthier living (on the part of the small 1% that haven't been absorbed into the fast-food culture!), and better medical care means more people are running into their 60s than before, and should contribute to improving records.

As for the mental aspect, 100% correct. I think that's a key part of it, and something that is impossible to pull out and analyse independently. So it becomes part of the equation, but a very important part.

Thanks also for those examples. They once again prove that for every rule, there'll be an exception. And I was at pains in Part 1 to point out that the performances of these amazing older athletes are neither proof nor rebuttal of the general principles. So while some athletes have gotten better with age and the right training, others will not, even with the training.

That's a function of health, motivation, training, all melted together with natural changes in physiology, and each of those things is entirely individual, so it is an endless topic!

I'll mention those athletes in the next parts of the series! THanks!


Ewen said...

Good subject.

Are there any scientific studies on the best ways to change running training as one ages in order to retard performance decline?

Obviously an older athlete can't train in exactly the same way that they did when at their physical peak (if they were training maximally at their peak). Some runners who appear to be improving as they age through middle-age are actually progressing their training year-by-year.

Would adding strength training or speedwork to a program be of more value than increasing easy mileage for example?

Anonymous said...

There are also non-running aspects to decline in performances. For instance, as we age we often find ourselves unable to run more not because of health reasons, but because we now have families or are climbing the career ladder and putting in more hours at work.

Losing muscle mass and strength can easily be remedied. In studies with folks in their 60s and 70s, men have added lean mass with a modest weight training program. However, that adds more time to one's exercise regimen.

For your consideration






Anonymous said...

Great series and I've been thinking about this since I read the Runner's World article a few months back that you guys supported. I was wondering if a decrease in Max HR naturally had to mean a corresponding decrease in performance. It would seem so if each race distance effort level was strictly based upon a % of Max HR. Or is each distance's effort level tied to a specific HR. Thus as the Max HR decreased speed disappears first and MP HR is untouched for years?

I'm 44 and have watched my max HR drop from 192 to 188 since I've been capable of measuring it. Yet last spring I ran my 10K PR (34:18) at a %of Max HR that shouldn't be possible.

The offshoot of this is that many people could be self limiting if they continue to drop the HR they think they can race at based upon charts. It makes degradation with age a self fulfilling prophecy.

Steve Pero said...

Agreed, I am enjoying this series a lot.
I am actually a good ongoing test subject as I started running at the age of 25 and am still running at the age of 57. Probably close to the same weekly mileage of an average of 50MPW, although in my younger running days I would spike up to and beyond 70 on occasion.
The only difference i find is that I am slower in both racing and training.
I always trained using a mostly low HR method (following Dr. Van Aaken in the 70's and Maffetone/Hadd today. but i will add that I have always added hills and then tempo's or intervals to maintain some speed.
My times have dropped more dramatically in the marathon, going from 2:49 (1981) to 3:45 (last fall). 5K had dropped from 16:32 (81) TO 19:52 (last summer).

I'm not complaining much because i understand it, but damn, my brain still wants to run in the 5's! ;-)

My plan is to continue the 50MPW training well into my 70's and beyond, if possible. I don't have any serious or new injuries, but just had to adjust the pace in order to recover completely before attempting another hard workout, which i now can only do once per week, rather than the 2-3 times per week when in my 30's.

Thanks for the great blog,

Unknown said...

So this article also explains why doping for master athletes, which sadly exists, could prove to be even more effective than for elite athletes..

Girl In Motion said...

"However, this is all a precursor to the more juicy and exciting discussion to come, probably next week. That's when we'll start looking at the impact of many years of running as compared to many years of living."

Where is it, where is it? :-) I'm dying to read this, as I'm Masters runner on 2-year old running legs. I'm so excited to read your findings on the subject.

Anonymous said...

In Part 1 and Part 2 you make the case that, because age-graded scoring tables are based on "perhaps 50 DIFFERENT INDIVIDUALS," that the equations are flawed for projecting "what your own time will be at age Y based on your time aged X."

While this appears to be clearly true for world record setting runners, the age-graded scoring tables can come pretty close to the mark for mere mortals. With an N of 1, this is purely anecdotal evidence but here are my three best marathons over a 25 year time span:
Age 31 - 2:50:08 - 73.4%
Age 43 - 2:58:03 - 73.7%
Age 56 - 3:19:28 - 73.9%

The percent scores are Age-Performance Percents calculated by a WMA Age-Graded Scoring Calculator using the 2006 tables. I would have more marathon data to report but after age 38 my hard efforts were primarily ultramarathons. The best of those ultras over the same period were in the 74-76% range for my age.

One possible reason the age-graded scoring appears to have predictive power in my data is that over the 25 year period I've only trained and raced hard for two or three years at a time. Each peak racing period was ended by some combination of loss of motivation, nagging injuries or life changes (job changes, moves, children, becoming a race director). Then, after three or four years of easier running, the hunger would return and I would get serious for another comeback.

Over the years I have been personally frustrated that I haven’t been able to stick with the grind and stay race fit for more than a few years at a time. In hindsight, there may have been a disguised blessing in that the off years gave my body a chance to recover so I could train and race hard during each comeback.

Tom Perry
Fairport, NY

edmunds said...

"The individual running 2:05:38 will NOT be running 2:19:29 at 50, and will NOT run 2:59 at the age of 72. We know this because it hasn't happened on a single occasion in all the age-group records that one individual holds records more than 9 years apart."

Joan Benoit doesn't quite have the 50-54 marathon world record for women, but her results point out that "NOT" may be a bit strong.

Keep up the good work!


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