Vigorous Exercise: Not Only for the Young—Part 3

As anyone that has read my blogs knows, I’m very interested in exercise and training, with a particular interest in geriatrics—I guess that’s because I am one!

I’ve written before that the amount of literature reporting on exercise and old folks is dwarfed by that reported on in the young; however, there have been several very interesting, recent reports regarding older adults.

The need for studies on the effect of exercise on older adults is urgent.   34% of US adults over the age of 70 have walking limitations; those reporting such limitations have a  four times higher risk of needing nursing home placement and are three times more likely to die than those with no walking difficulty.

That exercise lowers medical costs has been shown.  Studies have demonstrated that ON AVERAGE exercise improves physical function.  However, there are some niggling little facts associated with studies on older adults that are not generally known: not all participants in studies show improvement from exercise.  What??

For example, in a small 2005 study of adults over the age of 60 who were overweight had knee osteoarthritis, and who participated in exercise training for 6 months (aerobic and resistance exercise), 7.5% showed no increase in walking distance and 58% showed no increase in muscle strength.  Ouch.  

What’s going on here? Exercise is hard enough, let alone if you get no benefit out of it.

A study published in 2012 came up with related similar results looking at changes in insulin as well as high density cholesterol: an analysis of 1,687 adults over six studies concluded that 8.3% of participants had worse insulin numbers, and 13.3% had worse cholesterol results.

The point being that a portion of the population does not respond to exercise.  Or they may even get worse.

So, what accounts for this variation from individual to individual? Well, there are of course environmental reasons—but there are potentially genetic reasons, too.

The exercise literature has been examining one particular gene for more than a decade—the ACE gene (“angiotensin-converting enzyme”).  Everyone has an ACE gene, and there are two different types (alleles), called the “I” gene and the “D” gene.  

Therefore, people can be either II, ID, or DD for the ACE gene.

There have been many many studies on the ACE gene and athletic performance in young athletes.  IN GENERAL the I gene is found in elite endurance athletes—long distance runners, cyclists, rowers, and mountaineers.  The D gene is associated with “power” athletes such as sprinters or those that excel in strength related events.  I should add that there are studies that show the opposite results—however, the preponderance of the evidence is as I state above.   This seems to be an emerging pattern with respect to the genetics of athletic ability.

It may not be surprising, therefore, that ACE genotypes have been looked at with respect to how old folks respond to exercise—the question being,  “is some of the variability in older adults responses to exercise dependent on their ACE genes?”

There are at least two long-term studies involving oldsters and exercise.  One is the Health ABC study and the other is the Lifestyle Intervention and Independence for Elders  Pilot (LIFE-P).

The Health ABC study started in 1997 and 1998.  It enrolled about 3,000 people, males and females, whites and blacks, ages 70-79.  They had to be “normal,” with no limitation in their ability to walk a quarter mile or go up 10 steps without resting.

In 2005 a study analyzed these folks.  They found that at the initial start of the study there was NO difference between II, ID, and DD genotypes for a wide variety of characteristics such as weight, diabetes, hypertension, physical activity, etc. (Further, as points of reference, the frequency of the II type was 19.2%, 33.6% were DD, and 47.2% were ID).  

However, after 4 years they classified the people according to their level of physical activity, genotype, AND degree of “mobility limitation” (difficulty in walking a quarter mile or going up 10 steps without resting).  What they found was 1) the group that was most active had 18% less mobility limitation than the inactive group (providing more evidence that activity is good); 2)  that within the group that  had very low physical activity over the 4 years there was no difference between the genotypes; and 3) in the most active group the II, ID, and DD genotypes differed.

So, of interest here is point 3 above: in the most active group the II, ID, and DD genotypes differed in their response to exercise.  The II having the most mobility limitation and the ID and DD having the least; the difference between the II and ID OR DD being 45%.

Wow.  A 45% difference in mobility limitation.  The II genotype had HALF of the benefit of exercise compared with either ID or DD genotypes, and those that did weight lifting the greatest benefit.  Also, the II genotype had a higher percentage of body fat.

So, although exercise reduced mobility limitation, the II genotype had the poorest response. And remember they represent 19% of the population.  

The LIFE-P study is smaller than the Health ABC study, and started in in 2004.  It enrolled around 400 men and women who were 70-85 years old, who were able to walk 400 meters within 15 minutes, had a sedentary life style (spent less than 20 minutes per week on regular physical activity), and scored less than 10 on the SPPB test (discussed  below).  Persons with physical infirmaries, cardiac issues, and diseases of various types were excluded.  

The SPPB test (Short Physical Performance Battery) has become a kind of gold standard for quickly assessing physical capability for old folks.  The test includes determining how long it takes to get up and down out of a chair 5 times, how long one balances one’s self with the feet side by side or positioned heel to toe, and how long it takes to walk EIGHT (8) FEET, with a maximum score being  less than 3.1 seconds.  (Just reading these requirements almost makes me cry!).

An SPPB score of 10 or less (maximum of 12), means that there were “some” strength and balance issues

So in other words, these are older people who were pretty “normal” without major health issues.

There are around 400 people enrolled in the LIFE-P study.  Since 2006 there have been several studies published on this group of people.  A very early study, conducted after the program had been started for a little more than a year, showed that indeed, and unsurprisingly, individuals subjected to a combination of strength, aerobic, balance, and flexibility exercises performed better on SPPB test one year later than another group that only received exercise instruction.  

A study published in 2014 on 283 individuals enrolled in the LIFE-P study looked at those that were subjected to exercise vs. no exercise, and who were further classified into II, ID, and DD genotypes.  Exercise consisted of walking, strength, flexibility, and balance training. The strength exercises consisted of standing chair squats, toe stands, leg curls, knee extensions, and side hip rises with ankle weights.

So, first they found that those enrolled in the exercise group (E), maintained their SPPB score, while those that did not exercise (NE) significantly declined in their score.  Once again showing that exercise maintains performance.  But, of importance to this blog, in the E group there was a wide variation in SPPB score, with 33% experiencing a DECLINE in performance compared to 37% who showed a 2-point improvement in their score.  

So, with exercise, as with the Health ABC, a significant percentage of those had NO BENEFIT.  I suppose you can guess what comes next: they also looked at II, ID, and DD genotypes.

And what they found was, you guessed it (!), the II genotype had no or decreased performance—again like the Health ABC study.  

If this is borne out by future studies, then this is huge, in my opinion.  It may totally change how older adults are counseled with respect to exercise.  It is possible that some genotypes benefit most by, for example, walking, while others benefit most by doing strength exercises.

Helpful Resources:
http://jama.jamanetwork.com/article.aspx?articleid=201372
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0037887
http://link.springer.com/article/10.2165/00007256-200838120-00008/fullte...
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2657174/
https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF...
http://aginginmotion.org/the-key-to-fighting-physical-decline-the-short-...
http://pps.sagepub.com/content/5/5/575