I am going through a phase of getting bored with reading people’s opinions about training, fitness and diet. It is starting to take quite a lot to get me interested in a health or fitness article now.
The only things that really make me sit up and pay attention are where the author is writing about a recent study, a trend or about what Seth Roberts calls ”personal science”. Personal science is just data gathered from making observations in real life.
Essentially, personal science is actually real science but with lower barriers to doing experiments, more ecological validity and less statistical significance. It’s amazing how much we find out when we stop and observe things instead of just repeating what our favourite internet author said last week…
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Strength and conditioning
- Charles Poliquin’s team have reviewed a recent study showing that repeated sprints help improve judo performance. Charles suggests that such sprints could be useful for all martial artists.
- Brad Schoenfeld describes his experience of the recent NSCA conference, at which he was a speaker. Ever the educator, though, Brad doesn’t talk much about what he ate or drank, he tells us what the speakers had to say! Of great interest to me was his review of the presentation by Brent Alvar, who Brad reports as focusing on ”the importance of higher volumes of training in promoting increases in strength and hypertrophy.” Brad reports that Brent’s opinion is that “the single set approach, which certainly can produce gains, simply is not sufficient if maximal results are desired.”
Biomechanics, physiology and physical therapy
- Regular readers will know that I am very interested in the concept of elastic energy and how it is stored in muscles and tendons during running and jumping. My research reviews so far have suggested to me that elastic energy is not trainable or at least not easily trainable. I also am not convinced that there is much energy storage in tendons either. So I was very interested to read John Cissik’s reviews of two older studies that seem to suggest that the whole elastic energy theory is not as robust as we think it is. Check out John’s reviews here and here.
- I am as guilty as the next person of assuming that most people’s hip flexors are tight, as a result of following the lower crossed syndrome hypothesis. So I was interested to read Greg Lehman’s post about hip flexors and whether they really can be made tight by a sedentary lifestyle. I liked the way that Greg made it clear nothing in his post challanges the fact that typical lower crossed syndrome approaches are still very efffective in dealing with pain and dysfunction.
- Chris at Conditioning Research wonders whether there is a case to be made for older people to walk barefoot more. He notes an interesting study that reports how textured insoles make older people walk more carefully, possibly because of more stimulation to the plantar surface. Of course, encasing your feet in shoes for your whole life can’t be without symptoms of some sort…
Diet, paleo diet and evolutionary adaptations
- Primal Wisdom makes some very interesting points and references about the diet of the giant panda. Apparently, the panda has many of the hallmarks of a carnivore and very few attribute of a herbivore. I have to say that I think that some of the editorial around these points is a little aggressive – the argument is built up probably a bit too quickly. In particular, to dismiss changes in diet as a possible cause of modern disease because the panda was able to adapt to a herbivorous diet requires a lot more work than is found in this post and Pottenger’s cats at least deserve a passing reference if not an explanation.
Sleep, stress and health
- SAPT draws our attention to a recent study showing that exercise helps to regulate our circadian rhythms, meaning that it should help us get more sleep. The abstract says that “the molecular circadian clock in peripheral tissues can respond to the time of exercise suggesting that physical activity contributes important timing information for synchronization of circadian clocks throughout the body.” You can see the abstract here.
- Healthy Diets and Science reports on a recent study suggesting that adverse side effects cause 75% of elderly people to stop taking statins.
- And Dr Briffa argues that the side effects of statins may well go significantly underreported.
Other interesting stuff
- The Scholarly Kitchen talks about the importance of the peer-review process and why it is important for scientific study. It is very easy to be extremely critical about the politics and careerism that affects science these days (in that scientists doing the reviewing are often the people who will be submitting the next article, so they have to be nice!) so it is good to see a positive view point for a change.
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That’s all folks. I hope you enjoyed the new format.
Chris, Cissik seems to be confusing stretch reflex with elastic energy.
If you are unconvinced that the connective tissues store elastic energy, just snap your fingers.
As a trained partialist I am well aware that the resonant frequency of my own self gets lower with heavier weights.
These two latter examples are my own ‘personal science’ observations.
Juan, your frequency is always resonant and always makes me think.
Speaking of thinking, if I lean hard against a door frame and then the frame is removed so that my arm shoots forwards, have I stored elastic energy? Or if I lean a weight against a box and then move the box so that the weight falls over, has the weight stored elastic energy? I think that both of these are stored potential energy. I think the snapping of the fingers may also be mostly stored potential energy and not elastic energy.
However, I should have made it more clear that I do currently subscribe to the belief that there is stored energy in the muscles but probably not in the tendons and that either way it is not trainable.
Also, I think that John is reporting a study by Van Ingen Schenau, rather than putting forward his own views.
Juan, I have just been back to Cissik’s review and looked at his introduction. You are correct that he is mistakenly using the term “stretch reflex” when he means “stretch shortening cycle”. My brain translated it for me the first time around
Chris, whilst you are very scientific, it seems that Newtonian mechanics isn’t your strong point…
Your leaning against the door frame example isn’t very clear because there are 2 potential energies to consider. If you are leaning against it with bent arms and the frame breaks so that your arms snap forward into extension then that arm snapping is potential elastic energy being released as kinetic energy. Note that your arms snap forward far faster than muscle contraction alone could achieve. But as the frame breaks you also fall and this is potential gravitational energy being released as kinetic energy.
Thus you are misunderstanding the term potential energy. Potential energy is simply the energy contained in a body by way of its state or location. Thus when you snap your fingers you first generate tension by converting the chemical potential energy of the muscles into mechanical work which stretches the connective tissues – at that point your fingers are stationary and the potential chemical energy has become that of potential elastic energy. This elastic energy is released as kinetic energy when you let the thumb and finger slip sideways and snap.
You can certainly train yourself to use elastic energy and on the assumption that as one gets stronger one also adds connective tissue then one also gains more potential to store elastic energy potentially. I use elastic energy all the time to lift big weights, it is good for confusing HITers who are terrible with Newtonian mechanics.
Whether Cissik is reporting Van Ingen or not, someone is confusing stretch reflex with elastic energy.
Juan, my Newtonian physics is just fine (although I await the killer blow from your more keenly attuned engineer’s brain). I assumed that it would be clear that my arms were straight, hence the energy is 100% potential.
In the example with the person leaning against the door, potential energy is obviously created by virtue of the system being subject to gravity. I guess you could call this potential gravitational energy. In the example with the fingers being snapped, you correctly identify chemical energy as powering the muscles and creating the muscular force that draws the finger and thumb together. Again, while they are apart, you could call this potential chemical energy. However, you then insert another step to turn potential chemical energy into potential elastic energy, which you don’t explain in detail. Where is the stretch? I just see a force that is being prevented from doing what it wants to do.
I see it like a steam engine powering a device pushing against a door, which would be thermal energy powering a device creating a force against the door. Assuming that door was strong enough, there would be potential energy inherent in the system at this point. Opening the door would release the potential energy and the device would go through the doorway, turning potential energy into kinetic energy. No stretch, no elastic energy.
Re trainable elastic energy, I just haven’t seen it in the research yet. And what I have read suggests that it doesn’t happen. Of course, I am open to changing my mind when I see some research that contradicts this…
Also, there is in vitro research that suggests the connective tissue makes no difference to the elasticity of a system. I wouldn’t bet the farm on it at the moment but I don’t know of any research that shows the opposite.
Chris, you are making things even more complicated than they are with your steam device. Thermal energy of steam is simply the kinetic energy of the molecules bouncing around. This kinetic energy is what creates pressure, i.e. the change of momentum as the molecules hit the container.
This is not the same as snapping your finger. This is the same as setting a mousetrap. You use the chemical potential energy of the muscles to do mechanical work to store the energy as potential elastic energy. A mouse comes along and releases the potential elastic energy of the spring as kinetic energy. Thus;
Chemical potential energy > Mechanical work > Elastic potential energy > Kinetic energy
Formula-wise it might be something like;
ΔE > Wd > Fe > ½mv²
When you say, “I just see a force that is being prevented from doing what it wants to do.” this indicates you are not distinguishing between force, work or potential energy but instead lumping it together into a mysterious energy blob.
Ask yourself this. Snap your fingers now and look carefully at the speed with which your finger snaps. Where is the power coming for this speed? Don’t just call it potential energy as the term potential simply means energy that hasn’t been released. Ask yourself what is the form of potential energy being released? Is it chemical energy from your muscles? Is it thermal energy from your blood? Or is it elastic energy from the finger tendons?
Is elastic energy trainable? Depends what you mean. Certainly one can train to use elastic energy effectively whether it be in squats or jumping or partials.
Juan, apart from your slightly unkind inference about my ability to distinguish between force, work and energy, which is unfair, I don’t have a problem with anything you said there. When I see a boulder on a hill, I see gravity being prevented from pulling it downwards by an equal and opposite ground reaction force. To carry it up the hill, I must do work in moving it against gravity. Ignoring friction, the work is the product of the force of gravity and the vertical distance travelled. When it sits there at the top, it has potential energy by virtue of its position at the top. These are not mysterious concepts to me.
However, nothing that you said helps me get from modelling the finger snap as a boulder on a hill, or a plank leaning against a door (or anything like that) to a set mousetrap. That is the stage I need to see in order to agree with you that there is elastic energy stored. And you may well be correct, I do not know. But you are not explaining this step, you are merely repeatedly asserting it. Please help me understand how you deduce this step.
Incidentally, I have no idea whether the research supports the storage of elastic energy in a finger snap and I have never thought about it before.
By trainable, I mean “can you increase the ability of the muscle-tendon unit to store elastic energy?”
Chris, I am not being unkind… but you keep comparing finger snapping to a gravity well which is most vexing.
I get the general notion from your posts that you are mixing the term potential energy with gravity, when potential simply refers to any form of energy which has not yet been released.
If you roll a boulder up a hill you store the mechanical energy of your muscles in the boulder by converting it to gravitational potential energy. You indicate you understand this;
Work × Distance (of muscles) = Mass × Gravitational Acceleration × Height Lifted (of boulder)
If you snap your fingers you first generate tension. This tension must do something. In this case it deforms your fingers by stretching the tendons and so creating elastic potential energy;
Work × Distance (of muscles) = Force × Extension (of tendons)
Again I ask you to physically look at your fingers as you snap them and ask yourself where this speed is coming from.
Regarding whether one can “increase the ability of the muscle-tendon unit to store elastic energy”. I would say that it would almost be inconceivable that this was not so. For example when I first started squatting I could use 35 kg. If you had given me 160 kg my tendons/elastic structures would have snapped. Now I squat 160 kg so my muscle-tendon units must have got stronger, just as my muscles got stronger, and hence their ability to store elastic energy must also have increased.
Note, I should point out that all the muscle models I’ve seen include a spring component.
Again, Juan, you are concentrating on talking about all of the aspects that we agree on and (mostly) ignoring the step I am interested in, which is how you create elastic energy in a finger snap.
However, by referring to tension, you are simply restating your point (again) using a more technical term. Then you repeat the idea that the tendons are being stretched. And they may well be, I don’t know. But you are not helping me understand whether this is occuring and, if so, whether it is a meaningful level of tension in the context of the overall system.
If you can see the tendons stretching by looking at your fingers, you have more super powers than I previously gave you credit for.
Regarding your comments on the ability of a muscle to store energy, you seem to be confusing the ability to generate force with the ability to store energy. You must accept that it is possible to create a mechanical system that can increase its force production without affecting its storage of elastic energy?
Juan, I am going to shut down comments on this for the moment. Don’t take this the wrong way, I am really interested in this subject but I need to get S&C Research written and I keep looking at this instead. Let’s pick up in a week or so.