00:00:00one of the things that is a hallmark of AJ is a reduction in fast-twitch fibers these things are
00:00:05incredibly important can I change it with exercise absolutely you can't however you have to do
00:00:09something besides just run you need a combination of some sort of broad strength training and broad
00:00:15endurance and so these folks that were literally 80 or 90 their cardiovascular function their resting
00:00:20heart rate their blood pressure markedly healthier that number is about the vo2 max you would find for
00:00:25a normal college male if a saber-tooth tiger ran in the room or whatever and chased it down
00:00:30college men would probably have gotten eaten before the 90 year olds
00:00:33if you want to maximize health and overall functionality throughout time you need a
00:00:42combination of some sort of broad strength training and broad endurance I can actually talk about a
00:00:46couple of studies that I've done one of them we actually did in Stockholm Sweden and we worked
00:00:50with a whole bunch of cross-country skiers that were in their 80s and 90s and so they were
00:00:54competitive skiers the 1940s and 50s and they had been skiing competitively for that entire duration
00:00:59so you're talking 50 to 60 consecutive years of competing so these are 80 to 90 year olds living
00:01:05alone and healthy and we compared them to a group of individuals here in America who are the same age
00:01:10but were not exercising and what we wanted to do is to see and kind of look at what are these lifelong
00:01:15endurance individuals what do they look like so we ran them through a whole bunch of vo2 max tests
00:01:19and we did the same thing for those folks back here in America the standard number is about 18
00:01:24is what we call the line of independence so if your vo2 max is below 18 milliliters per kilogram
00:01:29per minute it's very hard for you to live by yourself so your fitness is so low you probably
00:01:34are going to need to have somebody living with you or you'll need to be in some sort of assisted
00:01:37living home so if you are in like vo2 max of 20 or 21 or 22 you're not below that line of independence
00:01:43but you're on that threshold and so what we found was our folks here in America the group average was
00:01:49right around that number so if they got a cold or they had anything pop up where they lost a little
00:01:54bit of fitness they were going to drop below that line and would probably have to go to some sort of
00:01:58assisted living situation the folks in stockholm the the cross-country skiers the group average was
00:02:03most closer to like 35 to 38 now that number is about the vo2 max you would find for a normal
00:02:11college male and so these folks that were literally 80 or 90 if a saber-tooth tiger ran in the room or
00:02:16whatever and chased it down college men would probably have gotten eaten before the 90 year olds
00:02:21so here here's the downside though so i only told you about the vo2 max what i didn't tell you about
00:02:26is their leg strength and functionality and that part was no more superior than it was their
00:02:31counterparts who were not exercisers so what that showed really really clearly you will see
00:02:36in general their vo2 max their cardiovascular function their resting heart rate their blood
00:02:41pressure it will be markedly healthier than folks who don't exercise it is extraordinarily clear that
00:02:46type of exercise is very important for chronic disease management no doubt about it however
00:02:51it is not sufficient for overall global health because it does almost nothing for leg strength
00:02:56for any other marker of health which we can talk about what are the things that are actually going
00:03:01to predict mortality morbidity the most you're leaving things on the table for your overall
00:03:05health now one could argue they're 80 and they're doing pretty well but they weren't doing as well
00:03:10in these areas and so a study we did later actually as a follow-up was looking at monozygous twins this
00:03:17is the perfect exercise scientific experiment monozygous identical twins mean they have the
00:03:22exact same dna so an egg was fertilized split and then two humans grew out of that with the exact
00:03:28same dna and so now we can start answering the question well what about maybe these cross-country
00:03:32skiers maybe they were just genetic freaks well genetics are always a component to it but how much
00:03:38well now we have a scenario lining up where it's like wait a minute you have monozygous twins so
00:03:41we have a replica of a human being exact same dna the only difference is that we would see in their
00:03:45physiology now would be due to lifestyle circumstances interesting do they exercise
00:03:51well one of them does he's a lifelong endurance exercise runner cyclist swimmer iron man all these
00:03:56things what about the other one nope he doesn't exercise at all all right i want to bring them in
00:04:00the lab but i'm not just going to look at one system i want to do everything so we took stool
00:04:05samples we took blood we did vertical jump tests we did maximum strength tests we did mris of muscle
00:04:12mass we did vo2 max tests we did efficiency stuff we did genetic testing we did an iq test we did
00:04:17psychological battery we wanted to look at everything to figure out of these things what
00:04:20differ between the twins and if so the second key question there is by how much and so again we had
00:04:26another example of a classic endurance only training paradigm compared to a person who's i think he's a
00:04:31truck driver they both exercised up through high school about 18 they stopped doing it by the time
00:04:35they brought them in the lab they're in their mid-50s so it's about 35 years of difference
00:04:38and when we ran them through the testing if you look at the the measures that were similar to the
00:04:43sweden study it was almost identical the exercising twin was significantly better at things like a
00:04:49lipid panel resting heart rate blood pressure vo2 max any of those markers what was very interesting
00:04:54though was the things that were in the middle first of all their total amount of muscle mass was almost
00:05:00identical like to the gram within the margin of error of a DEXA scan the non-exerciser though
00:05:06was a little bit fatter so the difference in actual body weight was explained almost entirely by body
00:05:11fat so okay like no one surprised there that the exerciser was a little bit leaner even though
00:05:16it didn't change the whole amount of muscle mass at all when we looked at some of the more functional
00:05:20tests and we looked at things like muscle quality you can kind of think about this as how much fat
00:05:24is inside the tissue but in general the muscle quality was not in favor of the exerciser if you
00:05:30looked at the performance testing and if you looked at strength it favored the non-exerciser so now
00:05:36again we have the same finding we saw in our sweden study but in identical twins so it really really
00:05:42highlighted the fact that if you want to move forward with optimal health simply picking one
00:05:47silo is not going to get you there can you change some of these metrics yeah not even close these
00:05:52things are very responsive regardless of your genetics your genetics will give you a starting
00:05:56place very clearly even the non-exerciser was a pretty healthy guy so they were in a good spot in
00:06:01mid-50s doesn't exercise doesn't really pay attention to his diet at all and he was in a pretty good
00:06:05shape however if you want to actually move progress and move for uh high functionality you have to do
00:06:12something besides just run now i could say the same thing for strength training because i don't want to
00:06:17make this seem like i'm saying endurance exercises it worked in both case both these studies those
00:06:22folks were much better off in metrics that are incredibly important to mortality how long you're
00:06:27going to live vo2 max etc it's just not going to get there in terms of strength we took a look at
00:06:34muscle fiber physiology as well which is very interesting there's generally two types of muscle
00:06:39fibers fast twitch and slow twitch and one of the things that is a hallmark of aj is a selective
00:06:44reduction in fast twitch fibers and that's because it's difficult to activate them unless you're doing
00:06:49high force activities you're going to activate slow twitch fibers doing almost any activity of
00:06:53daily living and so they stay around fast twitch fibers unless you're doing something of high force
00:06:58or going not be used and they're not going to be kept around and that's a problem because when you
00:07:02look at things like the need for leg strength the ability to catch yourself from a fall these things
00:07:07are incredibly important if you don't have fast twitch fibers you don't have the speed to get your
00:07:11foot out in front of you on time and you don't have the eccentric strength to stop the fall from
00:07:14happening and so if you look across again the aging literature they're very clear about the importance
00:07:19of maintaining strength and fast twitch fibers over time so we know that this is an important
00:07:23distinction and people will often talk about okay how much of that is genetically determined can i
00:07:29change my fiber type and the answer there is is resoundingly yes and can i change it with exercise
00:07:34and the answer is absolutely you can and the next question is how much so now again we're going to
00:07:38see an order of magnitude in general each one of your muscles in your body has a different percentage
00:07:44of fast twitch and slow twitch for example your calf that's generally mostly slow twitch
00:07:49typically 80 percent or so slow twitch the gastroc which is the other one right next to it so if you
00:07:53were to point your toe next to your face and that part that kind of flexes out in the middle that's
00:07:57your gastroc that is almost the inverse so it's generally 80 fast twitch maybe 20 slow twitch
00:08:02generally anything anti-postural or postural rather anti-gravity spinal erectors things that are meant
00:08:07to keep you up or moving all day are going to be slow twitch and things like your hamstrings which
00:08:11are for explosion are going to be fast twitch well we biopsy the quad in these individuals and in that
00:08:16muscle it's generally about 50 50 fast twitch slow twitch well one of the things that we found was in
00:08:22the non-exerciser it was almost textbook what you would predict it was about 50 percent or so slow
00:08:27twitch a little bit of percentage of fast twitch and then about 20 percent of what are these called
00:08:32hybrid fibers which are a hallmark of that activity in the exerciser it was about 95 slow twitch and so
00:08:38it's extremely clear i mean you're going from 40 slow twitch in one case to 95 slow twitch in another
00:08:43case it shows you that the limits of physiological adaptation are darn near boundless given enough
00:08:49exposure in this case 35 years of extremely consistent training and his muscle morphology
00:08:54was completely different than his identical twin with the exact same game