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Valve seats made after February are made of hardened steel and are fine for use with unleaded petrol. Toyota Corporate themselves told me this. It is beneficial to airflow to have multiple angles on the valve seats.
The stock seats are just cut at one angle, so the air deflects off to the sides of the chamber, the sudden change of direction also causes it to lose velocity, which is something you don't want.
Getting a three-angle valve job lets the air gradually curve around into the combustion chamber, retaining velocity for better air movement, and putting the fuel around the spark plug where it should be. You can get as many angles cut into the seats as you have the money for, or time if you're doing it yourself. I've heard of some perfectionists who cut 7 angle valve seats, almost like the seats are round.
I think it's alot of work for a diminishing return, 3 angles is fine. The most lift you can run with stock valve springs is about 0.
Whilst stock springs will definitely hit rpm without a problem, they'll de-tension fairly quickly say within a couple of years? What height aftermarket springs bind at depends on the thickness of the coil and how many of them there are. If in doubt, assemble and measure. Rob's head uses heavy Holden red motor springs, but you need to bore the spring seat down more into the head so these don't bind.
The stock spring seat pressure is 70lb 77lb for bigport Sprinter heads. From memory, Stewart's running some springs which fit and are lb. Anything between those two numbers should be fine.
Realistically, any valve can be used as long as it doesn't shroud too much against the edges of the combustion chamber hence, running oversize pistons enables you to run bigger valves more usefully than stock bore size does. David Vizard has some good rules for calculating ideal port size based on valve size, buy his books. Understand that the rocker pivots on an axis, and the valve moves vertically, hence the rocker must "wipe" across the face of the valve stem at some point whilst it moves the valve down.
It's better to have this lateral movement at lower lift, as it gives less wear to the valve stem and puts less strain on the whole lot.
You accomplish this by lowering the axis upon which the rockers move, which is supported by the rocker posts. Toyota had it pretty well setup from factory, so a good rule is to have the rocker posts accurately machined down by the amount of valvelift you have added to the engine. Stock lift is about 0.
There are two types of rocker post, early alloy and later cast iron. The cast ones are better, as the suffer less from thermal expansion it gets pretty hot in your engine you know and when the posts expand, they raise the axis upon which the rockers pivot, hence open up the valve clearance more, this is bad.
Changing from bolts to studs and nuts for the rocker posts is also a good idea, make sure you use high tension stuff. Valve clearance is there to allow the valves to cool in between combustion events spark , and to make sure the valve closes properly and contains the combustion explosion.
You need to cool the valves a little bit, the exhaust valve moreso than the inlet, as it's what sees the most heat as spent burnt gases go past it into the exhaust port. Run too little clearance and you'll cause the valve to "weld" a little bit to its' seat every time it closes, and then take seat metal off again when it opens. Do this enough times and you burn out the valve seat and need the head reconditioned. However, by running less clearance, the valve stays open for that little but longer, and you get more air in and out of the motor, and make more power.
Run too much clearance and your motor just sounds like a diesel and loses power and tappet rattle annoys you while you're driving, so it's better to err on the side of caution. The stock valve clearance 0. There are a few ways to set your valve clearances:. It's the quick and lazy method. Set engine to 1 TDC. Crank pulley timing mark should be on 0, distributor rotor should be pointing towards spark plug 1 or 2.
Set tappets counting from the front 1, 2, 3 and 5. Rotate engine degrees, crank pulley to 0 again, distributor rotor turned degrees. Set tappets 4, 6, 7 and 8. I've never really gotten into doing this, takes too much time and maths for my liking: P Rotate the engine through its' range of movement, as one valve is "on the rock" of its' max lift, subtract the valve number from 9 and that's the tappet you should be setting.
For example, if 8 valve is open, set clearance on valve 1. If valve 7 is open, set clearance on 2. Stewart uses this method, and rotates the camshaft through its entire base circle and sets the clearance at the highest point. Which is a pretty good idea, as it compensates for the possibility that the base circle has been ground unevenly, and allows you to run the proper valve clearance that you want to run, instead of something that may be a few thou larger in reality.
This gives the most accurate method of setting the cam timing, regardless of what clearance you're running. To degree in a cam, you'll need the specs of your cam, and to print off a degree wheel about the same diameter as the K motor crank pulley, and stick the degrees onto the pulley. Alternatively, you can buy a degree wheel at a speed shop. Start at 0 degrees TDC and rotate the engine through its' range of movement.
When you get to the timing when a valve should open or close, based on the position of the piston in relation to TDC or BDC, set the clearance on that valve to 0. I find with my higher compression and what not, my engine gets some weird thermal thing going with stock heat range plugs, and my exhaust tappets would unwind and over double in clearance, in the short driving distance of about km.
As an engine gets really old and starts blowing a bit of smoke, you might even find a hotter plug NGK BP4ES gives it a bit of oomf back, however do realise that the bottom end is approaching its' wear limit and it's time to start thinking about a refresh or new motor. Maybe in a very high compression EFI application where air-fuel ratios are fine tuned such as a If you try some and they make a huge difference, let me know.
A standard type head gasket will work fine. If you have oversized pistons, then you need an oversized head gasket to suit. I'm using a graphite head gasket, which doesn't use sealant of any kind. Graphite acts as kind of a lubrication between the two different metals on either side of it alloy and cast iron as they expand at different rates because of engine heat. A graphite gasket is a little thicker than a normal head gasket.
Don't make your gasket too thick or you'll destroy valuable quench area. Things like running a huge copper head gasket or doubling up head gaskets to lower compression are not good ideas, there are different and better ways to lower compression, such as porting the combustion chamber, modifying the pistons, or using a different head or pistons altogether, if possible.
There are a few types of distributors for these motors, which are covered elsewhere in the Wiki. I don't really have a problem with points, but some people do, so change to an electronic distributor if you want to.
What you really should do however, is get the distributor rebushed and recurved. Rebushing means to recondition the distributor so it has no play in the shaft, and gives reliably timed sparks. Recurving refers to modifying the advance weights and springs and sliders inside the distributor to change the way the distributor advances the spark as engine rpm increases.
Having the spark at an ideal point is important. If you ignite too early, you're exploding fuel which is working against the piston still rising to compress air, and wasting power.
If you ignite too late, you're exploding fuel which is "chasing" a piston down the bore and not providing as much energy as it could to move the motor, and wasting power. It's said that a modified motor generally needs less overall advance than stock, but a quicker advance curve. Base ignition timing is 8 degrees BTDC. I've found any more than 12 to be useless. It makes the motor quicker down low, but restricts the power the car makes at highway speed.
I think a good rule is to set the timing to suit the octane of the fuel. In the same fashion, you should reduce your timing if you're running 92 RON regular unleaded, maybe to 4 degrees, maybe 6, try it and see.
Having good spark is important, as it helps to make a better burn in the combustion chamber, so you make more power for the amount of air-fuel you have in the cylinder. Fitting a decent ignition coil is a good way to get better sparks. An efi coil would probably be a good idea, or a performance oil-based round cylinder coil.
Upgrading the ignition leads is a good idea, especially if your leads are the old stock ones. Over time, leads increase in resistance, and this reduces the power of your spark. I've had old stock leads that won't rev over rpm, they just break down inside. The lowest-resistance pre-made leads I could find were, surprisingly, Repco 8mm leads. Fitting a spark box high energy ignition or capacitor discharge ignition is the best way to get big sparks, though it needs the above two items to work to its' full potential.
These electronic boxes usually use the points as just a trigger, instead of passing the spark through them like the stock system, so your points don't suffer from bounce as easily, and don't wear anywhere NEAR as badly.
Doug and Stewart have these and they go quite well. They don't work with GT40 coils either, another reason to stay away from them. A capacitor discharge ignition kit makes huge sparks, and usually multiple sparks. I want to get one of these one day. When you get either of these kits, you could probably gap your plugs out from 0. You could probably go even further to 1. If you have a water pump that's working and doesn't look too rusty inside, keep using it. If you have one that's been sitting for a while, probably best to ditch it - the bearings don't like sitting for a long time and the seal must harden or something - they usually fail pretty quickly when put back on an engine.
There are several different types for K motors, the only difference being the fittings and sizes. Try get one that matches your current pump, or the hoses in your car if the current pump could be improved on. I haven't found any problems revving water pumps hard. The stock radiator will cool a modified engine if it's working well. I got it re-cored with a 3-row center and it works great, only ever goes above half when I idle for a while on a hot day. Make sure you have a thermostat installed or you'll cavitate the top housing.
I don't really think removing the thermostat and reinstalling the empty shell is a good way to solve cooling problems either. Drilling the thermostat is also of dubious value. Early Corollas had metal cooling fans, later ones had plastic fans, and the last KE70s had clutch fans. The metal fans are dangerous and you shouldn't use them, they're all getting really old and under stress, and like to shatter at high rpm.
Alex related to me a story of his old KE10 which he was in the engine bay of, revving the throttle wheel, when something went BANG next to him. The fan had shattered, and a blade had whooshed past his head and gone straight through the wall of the garage and continued on outside. If it happened while he was driving, it would have munted the bonnet pretty bad, and possibly harmed him or a pedestrian. I like the engine driven plastic fan, it moves alot of air even without a shroud.
You should fit a shroud, and the engine tray, to help create good vacuum to draw air through the radiator and through to the back of the engine bay faster. The shroud is positioned best when the blades of the fan are half in and half out of it, looking at it from the top. I wouldn't use a clutch fan, just something else to break, but if you have one and it works and you can't be bothered getting a new fan then just leave it. People fit thermofans sometimes, which is a good idea if done right.
Less reciprocating mass the engine has to spin, which is the fan AND the resistance of the air it's trying to move, gives an effect similar to lightening the flywheel. A thermofan needs to be mounted on brackets which reach out to the side of the radiator, NOT bolts through the fins of the radiator with rubber washers.
It also needs to have a shroud made up, which covers the whole face of the radiator and just has an opening where the circular frame of the fan blades is, or the fan basically just sucks around the circle and you don't use half of your radiator area. There are two types of stock alternator.
The Denso one is of smaller amperage, but seems to handle big revs alot better. The Bosch one fitted to Australian KEonwards Corollas makes 45A but old stock ones don't seem to be as hardy at rpm. You can underdrive the alternator with a larger Sigma pulley, or a reconditioned alternator usually works fine, maybe the bearings wear out quickly? The good thing about Bosch alternators is that you can upgrade them very cheaply and easily, by rebuilding parts from a higher amp Bosch inside the Corolla housing, you'll just need longer stator bolts.
This is what I have now. The stock alternator will work fine with the stock car, but if you're adding headlights and stereo and big ignition you probably need more amps, especially in a KEKE30 with a tired little 35A Denso.
There are upgrades available to take a Bosch alternator as high as A, this is what alot of large stereo cars have. Because you can make these engines pretty torquey, they'll bring out any weaknesses in engine mounts pretty quick.
Usually the manifold side goes, as it's exposed to the heat of the exhaust all the time, and it gets stretched under engine rotation, not compressed like the distributor side mount does. I'm onto my 3rd one in miles, but I'm using almost 40 yearold KE10 mounts so it's to be expected. A good way to fix this problem if you have it, is to make up a mount from the stock piece of metal which bolts to the block, and a Ford Escort or Cortina rubber, which is basically a thick rubber disc with two metal bolt threads in it.
You may have to weld a piece of metal plate to the stock mount to space it out enough, weld it to the face that sees the rubber, not the block but it works and works well. Ford mounts aren't dear from Repco, and usually wreckers have a big container full of the things you can fish thru and get for a few dollars.
And that's aftermarket, Toyota probably don't even make them anymore. Before I owned a Corolla, I'd never even changed a spark plug. I don't really have the money or the inclination to spend the money to pay someone else to build my engine for me, and I like to try different things for myself and have fun learning about the internal combustion engine and how it responds to changes in running conditions. So I built the motor myself, with no prior knowledge other than reading books and talking to people and pulling dead old free motors apart and trying to put them back together again.
K motors aren't hard to work on, they're actually very simple compared to other cars I've had the pleasure or pain of working on.
I also take pride in the fact that I can look at my car and think of every bit that I've had down to nut and bolt components, and think "Yep, got that sussed if anything goes wrong". And it makes the repair bills SO much cheaper when something does break. And these cars are getting years old or more, so things break and wear out all the time. However, I understand not everybody's that mechanically inclined, so if that doesn't inspire you to have a crack and slap the old girl together yourself, then you motor will be getting built by someone else.
Hopefully it's a mate and it will only cost you a carton. Generally, over half of the cost of a professional engine build is in labour, so think of what you're paying for parts and double it.
The only things I don't do myself are jobs that require a workshop full of expensive machining equipment I don't own, or stuff which I could do, but by the time I buy the tools it's cheaper just to get it done anyway.
Putting a head together is a good example, considering how expensive a valve spring compressor is, and how much of a pain in the ass valve seat lapping tools are, I really don't mind paying someone the money to use their professional and precise machine shop to do this for me.
If you've never built an engine before, you're going to need some tools - torque wrench, feeler gauges, measuring calipers, metric socket and spanner set to name a few - and a nice clean work area. You'll need an engine stand. Lubricate any moving metal-on-metal part such as bearing surfaces, lifters, etc in graphite grease aka: The only exception to this is the piston rings, just wipe the bore down with a light coat of oil before you put the pistons in.
Buy a Gregories or Haynes manual as well, so you know what goes where, in what order, and what torque setting to use. I personally find the Toyota factory service manual The Yellow Book to be most useful, but they're sometimes hard to find.
First time you start the motor, wind it over without spark until the oil pressure light goes off. You'll probably flatten at least one battery doing this. There are alot of different ways to run in a motor, and it seems to be a bit of a "black art". At the start, you want the engine to wear a bit, so the rings bed in and seal properly, and everything frees up and becomes happy with its new surroundings.
Some things take a long time to bed in, such as the rings, some things don't take as long. For example, the big end bearings and crank bearings will be worn in the first time you start the motor. Here's how I did mine. The first time I started the engine, I let it idle to operating temperature, giving a few revs a couple of times a minute to keep oil pressure up, then turned it off and let it go dead cold.
The next time, I drove the car for about 5 minutes, turned it off and let it go dead cold. The time after that was 10 minutes, then 20 minutes, then half an hour, then an hour, then I didn't worry about temperature cycling it so much. I ran running in oil for the first couple of hundred km or so. This is a fairly thin oil with lots of graphite particles in it. The graphite lubricates the tight metal parts as they try to rub against each other while the clearances are still really small.
The oil is thin, so you shouldn't rev too hard with it in, as you can squish thin oil out of the bearing gaps, and the oil can wipe away at high component speed, leaving a fairly bare surface with chunks of graphite and metal on metal which will score surfaces which should be lubricated.
After that, I changed the filter and swapped to a straight 30W oil, and kept this for a couple of thousand miles, then renewed the oil and filter with the same, and drove it for another couple thousand miles.
I then changed the filter and started off with the 5w synthetic oil, but later changed to the 15w semi-synth as described in the oil section. I tried to keep a sensible but gradually increasing rev ceiling. I took it to rpm on the first day I had it, then rpm on the next day, then I couldn't resist an rpm test run the next day.
I didn't flog the arse out of it from then on, but I kept it below rpm until I got rid of the running in oil. Once I'd changed to the synth oil, I was pretty confident the motor was going to hold together, so rpm became more of a regular occurrence.
I didn't hold it flat and reach the rpm limit of the stock carb until it was run in fully. A K motor is an old design, and uses fairly high tension rings. At the start of the engine's life, you want to put the engine under large vacuum conditions, so the rings "suck out" against the bore walls and wear themselves into the cylinder hone, so they provide a better seal. The way to do this is to get a long section of road with no stops, and drive along at normal town speed, shift into 4th or 5th and put your foot down, letting the revs slowly increase as the engine sucks air in.
Hills are really good for this, as you don't end up going too fast and speeding. Do this sort of thing as much as you can during the first miles, as this is when the most ring wear occurs.
Don't unnecessarily labour the engine, but don't just cruise with it either. The point is to be constantly changing the vacuum conditions of the engine.
Don't take it on a long steady drive, what you want to do is constantly vary your speed and gear, so you have to put your foot down, and that makes the rings suck out and wear in better. After about miles, I just drove the thing normally, there's not much you can do but wait, and you'll know when the engine is fully run in, it will get alot more powerful for no reason. Mine took 4 or miles. Run in period over. There's also no point trying to tune a new fuel supply on a fresh engine, its' needs for air and fuel and vacuum are constantly changing, so you'll find yourself changing the tune every week or month, and if you get it to lean out and detonate, or you can't get it started, or you put too much fuel down the sides of the bores, the engine won't seal up as well and you'll have lost power from the word go.
I'd say leave the fuel supply stock until it's run in, and you know a tune is going to last longer than the next miles. There are three types of stock manifold. The early KE10 manifold has straight runners and smaller inlets in the plenum area below the carburettor, Stewart used one of these manifolds when he did up his 4K, and continued to do so until he switched to EFI. I think one of the later ones might have gone better. There are two late type of manifolds, they both have curved runners which I think might be better for airflow, as well as larger holes in the plenum for the runners, as the runners are more spaced out than the straight manifold.
The difference is in the port sizes, sometimes you can find one which has larger ports approximately 27mm round, compared to the normal type which are about mm round.
Removing the manifold casting between the throats known as "hogging" the manifold is an old performance trick from the old V8 days, and it is believed that the increase in plenum area the bit between the throttle butterflies and the valves helps give the engine more response if it needs it, as it has extra air to draw from. A downdraft carb is easy because they're plentiful and cheap, and you don't have to modify much to fit them on.
Realistically, any downdraft is going to be a compromise on your power, because the air still has to turn 90 degrees inside the inlet manifold, from down to sideways.
I could write volumes on how to select a well-sized downdraft for your motor. You can't over air an engine, but you can slow down that air too much so that the engine isn't responsive and combustion suffers greatly. Generally, anything that goes well on a stock cc engine will go well on a worked You've got a bit of leeway with a 5K, as it draws more air.
I used a modified stock carburettor for ages when I did my motor up. They only flow about cfm, but the small throats makes them responsive and nice to drive.
They start to gasp for air about rpm, the slow down alot at rpm, and you can coax them to rpm if you try hard. I lathed my primary throat out 1mm and it improved the response of the engine out of sight, the thing was more snappy than some EFI cars I have driven, no kidding!
If you continue to use one of these Aisan carburettors, rest assured that it is your restriction point. I don't think Sprinter twincarbs would go too bad on a worked K engine, though you can get better fuel efficiency, and just as much power, out of a properly sized single, or sidedrafts.
A sidedraft is ideal for airflow. The ports are on the side of the head, the air should come in the side too. Buying new, don't expect much change from 2 grand. Twin 40s with 28mm chokes would be ideal, I think the 32mm chokes next size up would be a little too big but you could possibly get away with it.
I personally believe that SU carbs are fantastic. They're a throttle-type sidedraft with a vertically sliding piston which raises and lowers to both give a smaller throat, which improves airspeed, and to raise and lower a tapered needle, which seats into a fuel jet, to meter a different amount of fuel based on the airflow of the engine.
SUs can also be quite expensive, but you can get them cheap if you look hard enough. Any sidedraft is going to need some sort of custom linkage design. Genuine Weber linkages are ghastly expensive, but they work really well. You can make up something out of redline linkage arms and balljoints and a stock throttle wheel if you're clever. Or you can pay someone to make them for you, same goes for tuning. The early cars had a very basic emissions system, all the features of which are a good idea to keep if you can.
Ported vacuum advance is good as it allows the distributor to change the timing based on the conditions your right foot is placing the engines under, and how the engine is responding to the airflow at different RPM. The fast idle valve is helpful in summer, when your car will probably idle a bit higher because the air is less dense. The PCV positive crankcase ventilation system is so important it gets its' own paragraph.
K motors have alot of crankcase vapours, pistons just generally have alot of blowby and the rings start to float above the factory redline, so you need some sort of way to have these vapours sucked out the engine, or your oil gets ruined within km or less. The stock PCV valve and carby plate is fine if you're running the stock carb or a downdraft of some kind, just modify the plate to suit, or drill and tap another fitting into the manifold.
A sidedraft or SU may or may not have PCV functionality, in which case adding something to the manifold is the only way to go. Because of the way the PCV valve functions, nothing gets sucked out of the motor at full throttle. What you definitely don't want to do is not have a PCV system, you'll just pollute your oil quickly and make a big mess on the tappet and bonnet cover if you leave the pipes open to atmosphere.
I've used filters a chrome redline filter, and a little uniflow pod on the pipes before, and they still just make an oily mess. Use a plug or cap if you're sealing one off, a 10mm emissions cap fits great over the middle rocker cover pipe. KE10 rocker covers don't have this pipe, only the rear PCV valve pipe.
Later 4K-C engines had this god awful mass of hoses and valves and the exhaust going back into the inlet manifold and vacuum secondary throat on the carb and it was just awful. I don't know if you can rip all this stuff off and have it work again, but I'd be looking at doing something about it if you're keen on making power.
Likely the large overlap and varying vacuum conditions of a decent cam would confuse all the little devices anyway. To make power, you need to use more air, and that air needs to be mixed in a good ratio with fuel.
More power means worse fuel consumption, deal with it. The good news is that these are only small engines, so they don't use that much fuel anyway. My stock 3K in is best state of tune gave about 34MPG, or 8. When I race, obviously more fuel is used, but that's what racing is. The stock exhaust manifold is alright if you're just playing around trying to get your car running nicely.
There are two types of stock manifold, one has just one outlet pipe, the other has two pipes and is similar to tri-y extractors. Generally, as you add a larger cam, you need to have tuned length extractors and a larger exhaust in place, or all the extra air your engine is now moving is too much for the stock manifold to hold, and the exhaust gases pulse back up against the inlet charge and fuel comes back in a fine mist out of the carburettor. Second hand extractors tend to be a pest, in that either the middle pipe has bent out and doesn't like to seal, or the end pipe usually the rear is bent from a poorly hung exhaust pulling on it for so many years, and is hard to line up with the head.
I've always used second hand extractors which I got for free, and by far the best thing you can do to make the manifold easy to locate and seal is use studs and nuts instead of bolts. This also puts a more even force over the threads of the head, so you're less likely to strip a thread. The normal two-piece manifold gasket can also cause sealing problems if the middle pipe is bent, but an exhaust shop should be able to sell you a one-piece extractor gasket which is much better.
You can get metal ones which are alright, but I like the floppy asbestos type gaskets which are difficult to get these days. If your manifold gasket just won't seal, there's a chance the flanges of the inlet manifold and exhaust manifold or extractors if you're using them are different thicknesses. Any engine builder or machine shop should be able to grind the faces of the manifolds together for you, to ensure they're flat and sealing properly.
These aren't huge motors, the absolute biggest exhaust you want on any K motor is a 2" outer diameter pipe. Even that's a little big for most applications, and a 1. I'd say the smallest you'd go with performance in mind would be 1. I don't really think getting mandrel bends is worth the expense, you're not flowing a huge amount of gas. If you want to reduce heat levels in the engine bay a bit, make a heat shield from metal that sits between the extractors and the inlet manifold.
You'll notice the stock carb has an extension to the PCV plate that protects the float bowl from the heat of the exhaust. My heat shield is just two pieces of thin plate with a sheet of gasket material between them, bolted together and cut out in a rectangle with some indents for the manifold pipes. It's fastened to the extractors with hose clamps and holes drilled in the shield. What mufflers you end up getting will greatly affect the noise levels the engine makes.
A K motor can actually end up pretty noisy if you let it, mine's over dB! I'd suggest the longest resonator you can fit under the car, maybe even two if your exhaust guy can find space and there is space there , this will muffle the noise and give it a tough deep note. A shorter resonator will make it sound good but maintain the buzzy kind of noise which plagues all small capacity engines up high.
I'm using an offset flow straight thru muffler on the rear, and it's pretty noisy. The runner's high describes a euphoric state resulting from long-distance running. Scand J Med Sci Sports. This systematic review and meta-analysis found that physical activity reduced depressive symptoms among people with a psychiatric illness. The current meta-analysis differs from previous studies, as it included participants with depressive symptoms with a variety of psychiatric diagnoses except dysthymia and eating disorders.
This review provides strong evidence for the antidepressant effect of physical activity; however, the optimal exercise modality, volume, and intensity remain to be determined.
Conclusion Few interventions exist whereby patients can hope to achieve improvements in both psychiatric symptoms and physical health simultaneously without significant risks of adverse effects. Physical activity offers substantial promise for improving outcomes for people living with mental illness, and the inclusion of physical activity and exercise programs within treatment facilities is warranted given the results of this review.
Consistent evidence indicates that exercise improves cognition and mood, with preliminary evidence suggesting that brain-derived neurotrophic factor BDNF may mediate these effects. The aim of the current meta-analysis was to provide an estimate of the strength of the association between exercise and increased BDNF levels in humans across multiple exercise paradigms. Moderators of this effect were also examined.
Effect size analysis supports the role of exercise as a strategy for enhancing BDNF activity in humans. This omission is relevant, given the evidence that aerobic-based physical activity generates structural changes in the brain, such as neurogenesis, angiogenesis, increased hippocampal volume, and connectivity 12, In children, a positive relationship between aerobic fitness, hippocampal volume, and memory has been found 12, Mental health outcomes included reduced depression and increased self-esteem, although no change was found in anxiety levels This systematic review of the literature found that [aerobic physical activity APA ] is positively associated with cognition, academic achievement, behavior, and psychosocial functioning outcomes.
Importantly, Shephard also showed that curriculum time reassigned to APA still results in a measurable, albeit small, improvement in academic performance The actual aerobic-based activity does not appear to be a major factor; interventions used many different types of APA and found similar associations.
In positive association studies, intensity of the aerobic activity was moderate to vigorous. The amount of time spent in APA varied significantly between studies; however, even as little as 45 minutes per week appeared to have a benefit. Considered overall, the studies included in the present review showed a strong effectiveness of exercise combined with antidepressants.
Conclusions This is the first review to have focused on exercise as an add-on strategy in the treatment of MDD. Our findings corroborate some previous observations that were based on few studies and which were difficult to generalize. Moreover, we hypothesize that the main role of exercise on treatment-resistant depression is in inducing neurogenesis by increasing BDNF expression, as was demonstrated by several recent studies.
A Clinical Review and Management Guideline". Keeping in mind that exercise shows no medication side effects such as withdrawal symptoms 20 , weight gain, dry mouth or insomnia 21 , but shows potential health benefits such as weight reduction, it is highly recommended to use exercise as an adjunctive treatment for depression New findings confirm that exercise can be recommended as a first-line treatment for mild to moderate depression; as an adjunct to medications 23 ; as an alternative to cognitive behavioral therapy 11 ; and in preventing depression in clinical as well as healthy populations 24— Although recent findings have shown that exercise can decrease depressive symptoms, there are still many questions and limitations to wider application of exercise in depression.
For instance, there are deficiencies in methodological planning such as uncontrolled nonrandomized trials, small sample sizes, inadequate allocation concealment, lack of intention-to-treat analyses, non-blinded outcome assessments, and inclusion of subjects without clinical diagnosis that limit the interpretability of research outcomes The effects of physical exercise on cognition and behavior in children and adults with ADHD: The present review summarises the impact of exercise interventions 1—10 weeks in duration with at least two sessions each week on parameters related to ADHD in 7-to year-old children.
We may conclude that all different types of exercise here yoga, active games with and without the involvement of balls, walking and athletic training attenuate the characteristic symptoms of ADHD and improve social behaviour, motor skills, strength and neuropsychological parameters without any undesirable side effects.
Available reports do not reveal which type, intensity, duration and frequency of exercise is most effective in this respect and future research focusing on this question with randomised and controlled long-term interventions is warranted.
Lay summary — Exercise may improve thinking ability and memory 27 December In patients with MCI, exercise training 6 months is likely to improve cognitive measures and cognitive training may improve cognitive measures.
Clinicians should recommend regular exercise Level B. Exercise generally had a positive effect on rate of cognitive decline in AD.
A meta-analysis found that exercise interventions have a positive effect on global cognitive function, 0. Cognitive decline in AD is attributable at least in part to the buildup of amyloid and tau proteins, which promote neuronal dysfunction and death Hardy and Selkoe, ; Karran et al.
Evidence in transgenic mouse models of AD, in which the mice have artificially elevated amyloid load, suggests that exercise programs are able to improve cognitive function Adlard et al.
Adlard and colleagues also determined that the improvement in cognitive performance occurred in conjunction with a reduced amyloid load. Research that includes direct indices of change in such biomarkers will help to determine the mechanisms by which exercise may act on cognition in AD. Am J Occup Ther. All studies included people with AD who completed an exercise program consisting of aerobic, strength, or balance training or any combination of the three.
The length of the exercise programs varied from 12 weeks to 12 months. Six studies involving participants tested the effect of exercise on ADL performance These positive effects were apparent with programs ranging in length from 12 wk Santana-Sosa et al.
Furthermore, the positive effects of a 3-mo intervention lasted 24 mo Teri et al. No adverse effects of exercise on ADL performance were noted. The study with the largest effect size implemented a walking and aerobic program of only 30 min four times a week Venturelli et al.
Cochrane Database Syst Rev. A systematic review and meta-analysis of longitudinal studies". Longitudinal observational studies show an association between higher levels of physical activity and a reduced risk of cognitive decline and dementia.
A case can be made for a causal interpretation. Future research should use objective measures of physical activity, adjust for the full range of confounders and have adequate follow-up length. Ideally, randomised controlled trials will be conducted. On the whole the results do, however, lend support to the notion of a causal relationship between physical activity, cognitive decline and dementia, according to the established criteria for causal inference.
Role in Drug Addiction and Novel Treatments". There is accelerating evidence that physical exercise is a useful treatment for preventing and reducing drug addiction In some individuals, exercise has its own rewarding effects, and a behavioral economic interaction may occur, such that physical and social rewards of exercise can substitute for the rewarding effects of drug abuse.
The value of this form of treatment for drug addiction in laboratory animals and humans is that exercise, if it can substitute for the rewarding effects of drugs, could be self-maintained over an extended period of time. Work to date in [laboratory animals and humans] regarding exercise as a treatment for drug addiction supports this hypothesis.
However, a RTC study was recently reported by Rawson et al. Animal and human research on physical exercise as a treatment for stimulant addiction indicates that this is one of the most promising treatments on the horizon. Similar to environmental enrichment, studies have found that exercise reduces self-administration and relapse to drugs of abuse Cosgrove et al.
There is also some evidence that these preclinical findings translate to human populations, as exercise reduces withdrawal symptoms and relapse in abstinent smokers Daniel et al. In humans, the role of dopamine signaling in incentive-sensitization processes has recently been highlighted by the observation of a dopamine dysregulation syndrome in some patients taking dopaminergic drugs.
This syndrome is characterized by a medication-induced increase in or compulsive engagement in non-drug rewards such as gambling, shopping, or sex Evans et al. Am J Drug Alcohol Abuse. The limited research conducted suggests that exercise may be an effective adjunctive treatment for SUDs. In contrast to the scarce intervention trials to date, a relative abundance of literature on the theoretical and practical reasons supporting the investigation of this topic has been published.
From human to animal studies". As briefly reviewed above, a large number of human and rodent studies clearly show that there are sex differences in drug addiction and exercise.
The sex differences are also found in the effectiveness of exercise on drug addiction prevention and treatment, as well as underlying neurobiological mechanisms. The postulate that exercise serves as an ideal intervention for drug addiction has been widely recognized and used in human and animal rehabilitation.
In particular, more studies on the neurobiological mechanism of exercise and its roles in preventing and treating drug addiction are needed.
Sydor A, Brown RY, eds. A Foundation for Clinical Neuroscience 2nd ed. The clinical actions of fluoxetine, like those of many neuropharmacologic agents, reflect drug-induced neural plasticity, which is the process by which neurons adapt over time in response to chronic disturbance. For example, evidence indicates that prolonged increases in cortisol may be damaging to hippocampal neurons and can suppress hippocampal neurogenesis the generation of new neurons postnatally.
Neurotrophic factors are polypeptides or small proteins that support the growth, differentiation, and survival of neurons.
They produce their effects by activation of tyrosine kinases. Exercise-related improvements in brain function and structure may be conferred by the concurrent adaptations in vascular function and structure.
Aerobic exercise increases the peripheral levels of growth factors e. This finding has important implications in utilizing PA as a mediator factor for educational purposes in children, rehabilitation applications in patients, improving the cognitive abilities of the human brain such as in learning or memory, and preventing age-related brain deteriorations.
There is a significant association between the volume of the brain areas and their corresponding functions. Examples include the association of total and regional brain volumes BV with executive function and speed of processing, intelligence, working, verbal and spatial memory, and skill acquisition performance [27—29].
The connections between brain function and structure is due to the neural information processing being dependent on the size, arrangement, and configuration of the neurons, the number and type of the synaptic connections of the neurons, on the quality of their connection with distant neurons, and on the properties of non-neuronal cells such as glia .
This study showed that PA is positively associating with nearly all brain regions. Monoamines, Acetylcholine, and Orexin". Alterations in epigenetic modification patterns have been demonstrated to be dependent on exercise and growth hormone GH , insulin-like growth factor 1 IGF-1 , and steroid administration.
Investigating the dentate gyrus, a brain region which is involved in learning and coping with stressful and traumatic events, they could show that this effect is mediated by increased phosphorylation of serine 10 combined with H3K14 acetylation, which is associated with local opening of condensed chromatin. Consequently, they found increased immediate early gene expression as shown for c-FOS FBJ murine osteosarcoma viral oncogene homologue.
In fact the decrease of circulating IGF-I during short-term training seems to be reflective of favorable neuromuscular anabolic adaptation and is a normal adaptive response to increased physical activity. The potential for exercise-induced increases in circulating IGF-I seems to require longer training duration Aerobic exercise [Increased GMV in: Higher Cognitive Function and Behavioral Control".
The anterior cingulate cortex is involved in processes that require correct decision-making, as seen in conflict resolution eg, the Stroop test, see in Chapter 16 , or cortical inhibition eg, stopping one task and switching to another. The medial prefrontal cortex is involved in supervisory attentional functions eg, action-outcome rules and behavioral flexibility the ability to switch strategies.
The dorsolateral prefrontal cortex , the last brain area to undergo myelination during development in late adolescence, is implicated in matching sensory inputs with planned motor responses. The ventromedial prefrontal cortex seems to regulate social cognition, including empathy.
The orbitofrontal cortex is involved in social decision making and in representing the valuations assigned to different experiences. There is weak evidence for the effect of acute bouts of physical activity on attention. Fortunately, the literature-base on the acute effect of PA on the underlying cognitive processes of academic performance is growing.
Br J Sports Med: Journal of the International Neuropsychological Society: The excessive release of stress hormones, such as cortisol, which occurs in many individuals with mood disorders, may result from hyperfunctioning of the PVN of the hypothalamus, hyperfunctioning of the amygdala which activates the PVN , or hypofunctioning of the hippocampus which exerts a potent inhibitory influence on the PVN.
Chronic stress decreases the expression of brain-derived neurotrophic factor BDNF in the hippocampus, which in turn may contribute to the atrophy of CA3 neurons and their increased vulnerability to a variety of neuronal insults. Chronic elevation of glucocorticoid levels is also known to decrease the survival of these neurons. Such activity may increase the dendritic arborizations and survival of the neurons, or help repair or protect the neurons from further damage.
Stress and glucocorticoids inhibit, and a wide variety of antidepressant drugs, exercise, and enriched environments activate hippocampal neurogenesis. J Prev Med Public Health. In psychiatric patients, different mechanisms of action for PA and EX have been discussed: On a neurochemical and physiological level, a number of acute changes occur during and following bouts of EX, and several long-term adaptations are related to regular EX training.
For instance, EX has been found to normalize reduced levels of brain-derived neurotrophic factor BDNF and therefore has neuroprotective or even neurotrophic effects [7—9]. Animal studies found EX-induced changes in different neurotransmitters such as serotonin and endorphins [10,11], which relate to mood, and positive effects of EX on stress reactivity e.
Finally, anxiolytic effects of EX mediated by atrial natriuretic peptide have been reported . Humans report a wide range of neurobiological rewards following moderate and intense aerobic activity, popularly referred to as the 'runner's high', which may function to encourage habitual aerobic exercise.
Br J Sports Med. As phenylacetic acid reflects phenylethylamine levels 3 , and the latter has antidepressant effects, the antidepressant effects of exercise appear to be linked to increased phenylethylamine concentrations. The substantial increase in phenylacetic acid excretion in this study implies that phenylethylamine levels are affected by exercise.
A 30 minute bout of moderate to high intensity aerobic exercise increases phenylacetic acid levels in healthy regularly exercising men. The pharmacology of TAs might also contribute to a molecular understanding of the well-recognized antidepressant effect of physical exercise .
Rev Recent Clin Trials. It has also been suggested that the antidepressant effects of exercise are due to an exercise-induced elevation of PE . Ir J Med Sci. Therapeutic opportunities and challenges".
As initial trace amine research focussed largely on p-tyramine, 2-phenylethylamine, and to a lesser extent tryptamine and p-octopamine, the term subsequently became synonymous with these compounds. It deaminates primary and secondary amines that are free in the neuronal cytoplasm but not those bound in storage vesicles of the sympathetic neurone