January 10, 2009 
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The SAID principle is one of the most important basic concepts in sport science. It is an acronym which stands for Specific Adaptation to Imposed Demand. It means that when the body is placed under some form of stress, it starts to make adaptations that will allow the body to get better at withstanding that specific form of stress in the future. The adaptation process does not occur by any one mechanism – it is a general tendency of the body which is played out in innumerable separate mechanisms. While it is almost impossible to understand and account for all these separate mechanisms in devising a training program, it is easy to remember the general SAID principle – it means that the body is always trying to get better at exactly what you practice.
Let’s take some simple examples. If you place mechanical stress on the bones of the body by shock or impact, this will set in motion simple physiological processes that will thicken and harden the bones in the exact area of stress. For example, the place where your heel bone strikes the ground will be very hard and dense. The dominant arm of a tennis player will have larger bones than the opposite arm. Martial artists can toughen their shins and forearms into steel weapons through repeated shock training of the bone. The same thing happens with tendons and ligaments, which thicken and strengthen in response to mechanical stresses such as resistance training. Stress to muscles will cause them to get bigger, and so on.
The SAID principle also refers to adaptations that are far more sophisticated and complex, such as learning new motor skills. As you practice physical skills, there are numerous physical changes to the structure of the brain as a result. For example, if you spend hours practicing the piano, the part of your brain that controls hand coordination will actually grow larger. The neurons responsible for the coordinated finger actions will develop better and faster lines of communication between themselves. And your memories of hand skills will be placed into parts of the brain where they can be accessed and executed automatically, without any degree of conscious effort or thought. These are far more complicated adaptations whose patterns are described by motor learning theory, which I will describe in another post.
So if you want to get better at dealing with some some form of stress such as hitting a tennis ball or running 26 miles, start exposing yourself to the stress in question and then hope that the body makes some favorable adaptations. There are two major limitations to keep in mind. First is that the training stress must be the right amount and second, the stress must be sufficiently specific to ensure “transfer” or “carryover” to your sport or activity. Let’s look at these issues in turn.
The Right Amount
Stress in the right amount simply means not too much and not too little. If there isn’t sufficient stress, there will be no adaptation, and if there is too much stress, you will cause injury or burnout. If you want to strengthen your arm bones, tapping them with your finger won’t help, and a whack with a hammer will just break them. If you have been biking for years without improvement in your speed or endurance, then maybe you are not exposing yourself to sufficient stress to encourage the body to build the adaptations that will allow biking success. On the other hand, maybe your failure to improve is because each workout is too stressful, and therefore the body is failing to fully recover before the next workout and is instead just progressing into chronic injury. The basic rule about getting better at anything is to keep progressing the level of difficulty of the training without getting hurt or overtired. Very simple concept in theory, but it can be hard to apply in practice. Performance tends to plateau when the difference between too much and too little is so small that we can’t find it. The greatest athletes in the world such as Lance Armstrong are simply those people who are able to expose themselves to the greatest amount of stress without injuring themselves. At some point even Lance, with his optimal genetics and pharmacy will reach a point where further stress will only cause injury instead of adaptation. Most of us reach this point much sooner.
Carryover of Training to Sport
The carryover issue is a little more complex. Remember that that the S in SAID stands for specific. This means that the body only makes adaptations to withstand the specific stress it encounters – it has no interest wasting time making changes that don’t directly address the issue. For example, if you train your right arm, the right arm will get stronger, not the left. If you practice the piano, you will get better at the piano, not horseshoes. But if you practice the piano will you get better at the oboe? Maybe a little. In other words, there is a some carryover or transfer from piano to oboe. There’s probably a lot of carryover from piano to organ. How much does your training program in the gym carryover to the sport you are training for? The answer as confirmed by almost any study on this issue is – probably nowhere near as much as you would imagine.
Let’s use some examples. What about trying to become a better soccer player by using a swiss ball or other unstable surface to train your “balance.” Study after study shows that training on an unstable surface confers no measurable performance benefits on the field of play that could not be obtained by general exercise. In fact, people who train balance on a swiss ball are no better than anyone else at balancing with one foot on the ground! Why? It turns out that the mechanism by which the body balances on an unstable surface (called the “righting reflex”) is a totally separate mechanism from that which allows you to balance on a stable surface (called the “tilting reflex.” But you don’t even need to remember all that, just remember the SAID principle – if you want to get better at soccer, play soccer, don’t try to balance on a ball, that’s an entirely different skill.
What about using passive stretching as means to improve your “flexibility” in soccer and prevent a hamstring pull during a sprint or kick? Studies have shown repeatedly that pregame stretching does absolutely nothing to prevent injuries, and in fact makes you slower and less explosive for a short period after the stretch. Part of the reason is that passively stretching your hamstring on the ground is a completely different activity from actively kicking the leg out in front of you during a sprint or kick. In other words, stretching is not a specific preparation for soccer, and therefore violates the SAID principle. By the way, studies also show that you can effectively prevent injuries on the soccer field by a pregame warm up of the specific skills to be used on the field – like cutting, sprinting and kicking. The SAID principle in action again.
What about cross training – can you train your aerobic capacity for cycling by running or vice versa? Most studies show that there is some small amount of carryover here, but again not as much as you would probably expect. Sports scientist Matthew Wright estimates that the aerobic benefits that could be derived from 100 hours of endurance running might translate into the equivalent effect of 10 hours of endurance training for cycling. So why not just get on the cycle for ten hours? The carryover of cycling to running is even weaker, because running is a complex activity that relies to a much greater extent on skills of coordination, and bicycling is a much simpler activity. For example, consider Lance Armstrong, the greatest biker of all time and co-owner of the highest VO2max ever measured. He recently completed a marathon in about three hours – an excellent time for an amateur, but nowhere near where his performance would be if his aerobic capacity from cycling had a strong carryover to running. He said the race was one of the hardest things he ever did. More proof of the SAID principle.
So, in summary, remember to keep training simple – if you want to get better at X, do X as hard as possible without getting hurt or overtrained. Be very skeptical of the carryover or transferability of “functional training” or even training that purports to be “sport specific.” Chances are, its not.
Better Movement 
Nice!
Can I make a plea to remove the implication that Armstrong took illegal drugs? He’s nearly the only athlete I stand behind, since he’s one of the most tested athletes in history, and has never been found guilty of taking anything illegal.
I just read that he’s been tested over once a week in the last 10 months leading up to the tour.
Craig,
Hmm, I guess its unfair to smear Lance without really knowing anything about the issue. How about this, if he performs well on the tour I’ll take it back. But if he gets crushed I will leave it up.
hi mate
loved this article. agree totally with the stretching pre game statement and think fitness professionals within sports team have alot to answer for.
do tyou think the implementation of, not incorrect, but less functional techniques by fitness trainers with regards to top athletes leads to a slight detraining effect within their activity, as there is still far too many non-impact type injuries ocurring in high level sports.
I am convinced these would be avoided if the athletes are being trained in ways that more functionally meet the demands of their sport.
would be great to hear your views on this via email. take care
Darren,
Good question. I think many top athletes are training in ways that are “wrong” such as an overemphasis on stretching, but who can argue with the results. Amazing athletes will overcome a poor training program even a poor diet. I assume they would be better with an optimal diet and optimal training, but its possible that at their level of genetic freakishness, there is only a minor additional benefit to be gained from from optimizing these factors. Maybe for the average trainee there will be more benefit to diet and training optimization. I know for me this the difference between being a player and a spectator.
Very good post! But (and forgive me if this is answered elsewhere, I just found this blog) you seem come very close to suggesting that the only training necessary for soccer is playing soccer, the only training necessary for cycling is cycling, etc. But isn’t true that greater strength, in general, helps an athlete perform better and that improving strength requires loads that you just don’t get from playing the specific sport?
E.g. a stronger athlete can jump higher, but jumping alone does not necessarily make you stronger. (Actually, vertical jumping is a bad example, because it is an explosive movement that actually does recruit the fast-twich fibers in a way that other sports movements don’t, but you get the point.) Squats done with a sufficient load will build stronger quads, hams, glutes, etc. which do translate to things beyond “being better at squatting.”
Would you suggest that someone who squats 315 and deadlifts 405 would be no better at moving a sofa compared to someone who squats 135 and dealifts 185?
Anyway… maybe you address this somewhere else, but it seems this post is eliding, somewhat, the difference between skill adaptation and the overal strength adaptation that comes from a good program of compound-lift weight training.
That aside, this is a great blog!
Glenn,
Thanks for the comments. I’m not saying strength gains will have no carryover on the field, just that it will probably have less than most people imagine. I would imagine that about 90% of getting good at soccer is achieved by playing soccer or doing soccer specific running or skill drills on the field. The weightroom will help prevent injuries and maybe improve some other factors a little, but most of it is just playing the game.
As far as moving sofas goes, I will take a guy who moves a lot of sofas over a guy who does a lot of deadlifts. Of course all things equal I’ll go with the guy who has a bigger deadlift.
Todd,
I see your reply to my comment, but not my comment… or am I missing something?
With all due respect, I have to disagree. The idea that strength training has little benefit for athletes, who should mainly just practice their sport, is about three decades out of date.
You are vastly overstating the applicability of SAID (and defining it very narrowly). What SAID means is that if I do partial squats and don’t activate the posterior chain, I won’t get a stronger posterior chain. If my knees collapse because of weak abductors, I have to target my abductors, because they will only grow if I stimulate them. But… it does NOT mean that if I do proper squats and develop stronger legs, then I have only gotten stronger at performing squats. Strength is not that narrow.
I do heavy squats to develop a stronger vastus lateralis, biceps femoris, glute max and med, etc. When they get stronger, they are stronger. Period. I may need to develop the neural motor pathways to apply that strength to soccer kicks, e.g., but the strength itself does not flick off when I do leg work other than squats, and then mysteriously flick back on again when I put a barbell on my back.
You are also omitting a whole host of other responses that are elicited by heavy resistance training, including bone, tendon, and ligament strength; training the CNS to recruit fast-twitch fibers; the hormonal response, etc.
Despite this disagreement, I still love this blog!
Glenn,
Thanks for the comments. I think I added your original comment is restored I’m not sure what happened there.
I don’t think I’m overstating anything here by saying most of getting good at sports is playing the sport. If you wanted to get much better at soccer and had 10,000 hours to practice, what percentage would you be on the field playing or practicing soccer versus time spent in the weightroom? I would hope you would spend at least 90% of your time and energy on the field as opposed to working on your squat or deadlift. The weightroom would be supplementary and would mainly help to prevent injuries. Sure it might make you a little faster or quicker too, but most of soccer ability comes from playing soccer, not squatting.
If you get “stronger” glutes from squatting they are not stronger period. They are stronger at squatting and doing similar activities. Although the muscle fibers might be bigger period, they are hooked up to a nervous system that gets to decide when and how they fire. So yes, the strength does flick on and off when you change activities. “Stronger” legs won’t necessarily help you kick a ball harder or cut faster. In fact, lots of squatting could easily make you worse at ether activity if they cause a little pain, take time and energy away from skills practice, or change your movement patterns in some way.
Changes to bone tendon and ligament strength are certainly elicited by strength training and could be helpful for injury prevention on the field. Of course, they are also elicited by playing your actual sport, and in this case they are gained in exactly the places and amounts where they are needed, and not where they aren’t needed, as would be the case with adaptations gained in the weightroom. Look at the pic of Nadal above. His left arm is way bigger than the right. That is from hitting a tennis ball, not lifting weights.
One final point. I don’t think that weight training is useless for athletes. I think it pales in comparison to actually playing your sport. Because you can’t play your sport all the time without getting hurt, it makes sense to get in the gym now and then. But this is supplementary, not primary.
Todd,
Thanks for the reply… and your points are well taken. I think we may still disagree slightly on the percentages, but it’s just quibbling at this point.
Looking forward to any new posts!
Glenn mades ome good points but I would have to agree with Todd
here.
I was a professional (competitive) arm wrestler for 15 years and
even though I’m retired from the sport it’s still a big part of
my training because I train others at AW as well.
Arm Wrestling may be the best example I can think of that’s inline
with what Todd is saying. If you look at all the elite arm wrestlers
in the world and ask them about their training they will tell you that
pulling other people is MOST of their training. Yes, many use weights
in a fashion similar to AW movements but nothing can compare to actually
arm wrestling to be good at arm wrestling. There’s not one National or World Champion AWer that I know of that got stronger at AWing by lifting weights.
The greatest arm wrestler ever in the sport, John Brzenk (whom I know personally)
will tell you that he achieved his arm wrestling strength/power from arm wrestling
ONLY. You want to be the BEST, observe waht the BEST are doing.
Great blog here! Learned a lot.
Joe,
Great information, thanks for sharing, and yes, great example of the SAID principle. I have never arm wrestled, but would imagine there is a huge amount of skill involved, in addition to the brute strength.
Hi Todd,
nice post
couple quick questions:
do you have references to show how get that cycling is less complex than running? i’d appreciate taking a look at ’em.
running, as bipedal, means that there’s less balance involved than cycling, no? the biggest difference seems to be that in running there is more upper body work than cycling, so arms unused to moving are going to fatigue? so would be keen to see how the researchers were factoring this?
likewise, there’s no doubt about lance armstrong’s vo2 strength, but i’m not sure he was running to win per se? or that he was particularly flattened by the end of it, or had been training for very long – i don’t know in other words how conditioned or not he was relative to the event.
If we think about threat modulation
armstrong’s training program for races is to go out and ride entire segments of a race course so that he is familiar, comfortable, reduced threat with the course – in all kinds of weather.
Did he go through these same adaptation rituals with his running? did he care? or was he going just for fun?
So i’m not sure we can make the comparison that there was a “lack of transference” in terms of cardio vascular preparedness, vs other factors of familiarization/practice that reduce threat.
SO SAID yes, but perhaps not so much in terms of physical systems alone, but with those threat components in z?
on the music front? my experience is you can hand a musician just about anything and they’ll shortly get good sounding music out of it. agreed keyboards transfer more readily to keys and strings, seemingly to strings, but haven’t seen that been a particular barrier to most musicians who feel comfortable improvising. Perhaps lower threat about performance so easier to apply skills from one domain to another?
just some thoughts
mc
MC,
Thanks for the comments.
Here is a ref that (supposedly) shows that running transfers better to cycling than vice versa. Tanaka, H. (1994). Effects of cross training. Transfer of training effects on VO2max between cycling, running and swimming. Sports Medicine, 19, 330-339.
I am not an expert on cycling but would guess that it is far less complex than running. Gait is like a signature or fingerprint. There are a million ways to run, some better than others. You could recognize a familiar person walking or running in silhouette from one hundred yards in an instant. You would instantly recognize a great runner even at a glance. I don’t think any of this is true with biking.
I admit Lance apparently didn’t train very hard, didn’t expose himself to the specific threats of running and wasn’t prepared for the race. That’s why he didn’t do well, no specific training. He said it was one of the hardest things he ever did.
Of course the cycling had lots of transfer, but not as much as many people would expect. He is one of the fittest athletes in the world and ran a time that many people can run without even being a runner in high school.
With regard to music, I agree that there is definitely some transfer from one instrument to another. I would imagine that the similarity of the skill set is a more important factor in the transference than the similarity of the threats.
I have a question for example if you were practicing boxing and trained with components that made you work harder at the sport like heavier gloves or a vest weight or footweights would you then improve your strength and skill at boxing or other sport while doing the sport instead of working out at the gym? for example if you were running and you were trying to improve balance would it be beneficial for someone to try and push you for you to get better balance or running an obstacle course? or if you were trying to get explosive power and speed for running would it be beneficial to strap on a parachute for resistance? or in boxing for strength would it beneficial to strap some sort of concoction that adds resistance to your movements while boxing? basically im just asking does adding resistance to specific movements in sports increase your strength or speed at the sport itself? or to a lesser extent endurance?
Jeff,
Good questions. Many athletes have tried to improve their speed or strength at a sport related activity like throwing or hitting or kicking by increasing the resistance while throwing or hitting, such as using a heavier ball to throw with. The verdict on this type of training activity is definitely negative. Studies show that using extra resistance to perform a sport specific activity actually makes you worse, not better. The explanation is that doing the activity with extra resistance is actually a slightly different skill than the actual sport activity, so that the new skill interferes with the one you want to perform in the game. So, for example if you throw with a heavier baseball, this practice this will actually make you worse at throwing with the regular baseball, partly because it will subtly alter your throwing mechanics for a different ball. I think the same logic applies to parachute for running, although I don’t think I’ve read studies on this specific issue.
If you want to get better at running an obstacle course, I would practice running on obstacle courses. Maintaining balance while someone pushes you is likely a completely different skill, useful on the soccer filed maybe, but irrelevant if your sport doesn’t include people pushing you while you run.
This S.A.I.D. principle is simple yet at the same time so complex its almost like saying. training at whatever it is that you do, sports specifically, is all you need to do to get better at it. It definitely does seem to make sense when you look at it from a point of view that is different from all the meathead’s point of view, who train all their live’s in the gym and boast that they’re better athletes without any scientific or sport specific backing. Me personally I train at the gym for aesthetic purposes but with this new info I think I’ll take my sports training elsewhere thanks for the free info you put up here it really brought insight into how I should handle future training methods.
Hey Todd – One thing I’ve always been curious about is ‘fitness training’ for tennis players. Agassi talked in his book about how he kept failing to go the distance until he started hitting the weights, running, and doing hill sprints with Gil Reyes. I’ve always thought this is a coincidence and he simply got better at playing 5 set matches by playing more 5 set matches. That combined with the mental factor of knowing he put in that time in the gym (even if it didn’t really do much for your tennis) may have helped him push past the finish line. Big surprise that Federer and Rafa can go the distance when they go 5. They have belief AND they’ve played more best of fives than almost anyone.
It’s funny because you hear it SO often in professional tennis from commentators that ‘the guy really put in a lot of work on his fitness in the off season and it really shows’ What do you think? Are they just blowing smoke or is there something to it?
Tom,
I’m not really sure how much off court work contributes to match fitness. I’m sure it must help some but the question is how much. I would take a wild guess that maybe 80% of the physical qualities required to play tennis come from playing tennis. But you can only play so much tennis without getting hurt. The off court work is a potential way to practice more hours of the day without stressing areas that are overworked on the tennis court. Those hours won’t transfer as well to tennis as simply playing tennis, but they must transfer a little. I think this is particularly the case when the qualities developed off court are more mesodermal (e.g. bigger muscles, more mitochondria) as opposed to ectodermal – (e.g. neural adaptation to exercise.)
Please let me know if you’re looking for a author for your site. You have some really great posts and I believe I would be a good asset. If you ever want to take some of the load off, I’d love to write some material for your blog in exchange for a link back to mine. Please shoot me an email if interested. Kudos!
Now now Danette, but thanks for the offer.
Hi Todd,
Your blog is terrific. Did you write for the Courant in high school? If not, we sure could have used your talent.
I teach Reading to high school students in Palm Beach County. Many of my students are interested in careers as professional athletes. I think they’ll find your articles both interesting and informative.
Best regards,
Kathy (Eich) McPherson
Hey Thanks Kathy! I did not write for the Courant. But no loss I could barely form a sentence in high school!