Sunday, July 28, 2013

Are the exercise recommendations insane?

I try to stay fit. I lift weights. I do crossfit. I do judo, and I still practice at a fairly respectable level. Since I found the training diary Funbeat about two years ago I have been keeping a detailed training diary. Recently I went through my training statistics and came up with some interesting numbers. In the last two years I have trained 262 times for a total of 285h 29min. That comes out to about 23 minutes per day or 164min per week on average.

Now, let us have a look at the exercise recommendations from the World Health Organization, Centers for Disease Control, or the Swedish equivalent Folkhälsoinstitutet. Here follows the text from the WHO, the others are exactly the same.

Adults aged 18–64 should do at least 150 minutes of moderate-intensity aerobic physical activity throughout the week or do at least 75 minutes of vigorous-intensity aerobic physical activity throughout the week or an equivalent combination of moderate- and vigorous-intensity activity. Aerobic activity should be performed in bouts of at least 10 minutes duration. 
For additional health benefits, adults should increase their moderate-intensity aerobic physical activity to 300 minutes per week, or engage in 150 minutes of vigorous-intensity aerobic physical activity per week, or an equivalent combination of moderate- and vigorous-intensity activity. 
Muscle-strengthening activities should be done involving major muscle groups on 2 or more days a week.
We immediately notice that I follow the minimum guidelines of 75 minutes of vigorous-intensity aerobic activity, and two days with muscle-strengthening activities. But we cannot say that I fulfil the guidelines for additional health benefits. On average I do 164 minutes of exercise including strengthening activities. Of course, we might argue that I ride my bike to work, walk the dog, and go shopping so that I easily fulfil the quota. However, the guidelines specify at least ten minutes duration, and in the complete text specify that you should raise your heart rate and break a sweat. Even going as far as specifying that just shopping or walking the dog does not count for most people because the intensity is too low, so that argument does not work.

In the end we must find that I have a hard time keeping up with the guidelines. At the same time, with that activity level I am able to practice judo with our ten to twenty year younger elite and junior players. I am stronger than I ever was, and have as high endurance as I have had since I stopped swimming. For those (like me) who like numbers that means a 170kg dead-lift, a 90kg bench-press and a 124kg back-squat, and endurance-wise a VO2max of around 60ml/(min*kg). Nothing spectacular, but clearly very fit for a 35-year-old nephrophysiologist.

How can we possibly expect our patients, and the public in general to be able to train that much? And, would I actually increase my expected life-span and number of healthy days by more than doubling my training? For breast and colon cancer the guidelines say:

Data indicate that moderate- to vigorous-intensity physical activity performed at least 30–60 minutes per day is needed to see significantly lower risks of these cancers.
60 minutes per day? On average? For enough time to affect cancer mortality? Who the fuck even completed these studies?

Friday, July 26, 2013

Newton's law of cooking chicken

Newton's law of cooling can be used to predict the time of death from the temperature of a corpse and the ambient, which is a silly and boring example. On the other hand, when we are cooking chicken and our better half asks when it will be done (and demands that it be done in a given time), then it becomes an interesting and useful equation. Let us say that it has already cooked for almost an hour, it is around half past seven, and dinner is supposed to be at eight.

The important point is that Newton's law of cooling is equally applicable to cooking because physical law is symmetrical, which means that cooling and heating behaves the same way. The law states that the rate of change of the temperature of an object is proportional to the difference between its own temperature and the ambient, or
dT(t)/dt = -k(T(t)-Tambient)
where T is the temperature of the object, t is time, k is a constant, and Tambient is the ambient temperature. It is a differential equation that solves to 
T(t) = Tambient + (T(0) - Tambient)e-kt
which we can use to calculate the temperature we have to cook the chicken at to be able to serve dinner at eight(-ish). The only problem is that we have to know the constant k which is specific to the particular chicken and filling we have in the oven. Luckily, we used an oven-thermometer, and we kind of remember how long it has cooked already. So, if it took 50 minutes to go from 10°C to 53°C with the oven at 150°C then we can calculate the constant as
k = -1/t ln((T(t)-Tambient) / (T(0)-Tambient))
that is
k = -1/50 * ln((53-150)/(10-150)) = 0.0073 min-1
In turn, we can use this to calculate what temperature we have to use for the chicken to be done in another 30 minutes as
Tambient = (T(t) - T(0)e-kt) / (1 - e-kt
 which gives
Tambient = (80 - 53*e-0.0073*30) / (1 - e-0.0073*30) = 200°C
Luckily, we didn't have to do the calculations by hand because a bigger nerd than us have created a web-app where we just plug in the known values and get the missing one for free.

Finally, here is the money-shot.
Science, because it works bitch.

(Although the higher temperature did burn the skin a little bit, and it would have been jucier if it had cooked at 150°C the whole time.)

Wednesday, July 17, 2013

A matter of questionable importance

One of the most important aspects of reading is to have a good place to read. Crazy, you say. Any place is a good place to read, and of course you are right. When I was younger I would read all the time and everywhere, walking around bumping into people, missing my bus-stops, and getting reprimanded in class. Indeed every place was a good place to read, but now it's different. Wherever I find myself I have somewhere else I should be, or I have something that more or less urgently needs to get done. So when at home, when at rest, a special place to sit and read and think is an important thing. A place of solace (A fortress of solitude! No, too much?).

It is obviously not as important as roof over your head or food and clean water, but important never the less. For years I haven't had one, and I haven't read as much as I used to. It has simply not been a priority when furnishing the flat.

Anyway, we were at IKEA the other day and there was this new armchair model. Simple, not overly large, really cheap, and above all with side head-rests. I had to have it. There have been a number of armchairs I have had to have over the years, but since this was simple, small and cheap I could buy it on impulse. Now I have the ideal reading corner, and it complements my life-sized decorative boxer perfectly. It is close to my books, but not the work books, and it is far away from the computer and the heaps of manuscripts, applications and statistical analyses to be worked on.

I do have a small confession to make. I am writing this in said chair, and I did just check my mail, but then rules are made to be broken. Especially small silly rules with no real fundamental importance. Anyway, there shan't be too much work done here, and I shall honestly try to get some reading done real soon now.

Friday, July 12, 2013

Climbing to the top - Kidney Camp 2013

"Kidney" CAMP!

The FASEB Science Research Conference on "Renal Hemodynamics: Integrating with the nephron and beyond" took place last week at Vermont Academy in Saxton's River, VT. The meetings were previously called Summer Research Conferences, but they changed that to the quite strange "science research" that sounds more like a branch of philosophy to me.
Anyway, we still call it by its proper name: Summer Kidney Camp. It is a summer camp where spouses send their kidney physiologist halves to wear them out and enable at least a semblance of normal conversation during the rest of the summer. I'm guessing that doesn't work out as well as they hoped in much the same way as summer camp for kids don't.
The Kidney Camp is held every three years, and has a tendency to return to Saxton's River, even if it has been held in other locations once or twice. The main feature is the afternoon-break where we do important sciency stuff, like sitting in the grass, playing softball, football (proper football), basketball, and top rope climbing (which, by the way, is awesome). As far as I can tell most attendees only play sports once every three years for reasons unknown to science, and quite dangerous to be honest. The climbing was probably the safest activity.
The evenings are filled with more science. The fiercely competitive talent show, which was won by one of the supporting acts. The collaborative table tennis, and the very novel fussball table (rumor has it the last one broke three years ago) where any argument can be settled with a well timed spinning of the rods.
Then we have billiards, which makes you look better, but only until you pop the cue-ball off the table. Aaron, who is posing for illustrative purposes only, never did. I promise. Honestly.
In between these important scientific sessions there were some other stuff, where a lot of actual science was actually discussed. Some six to eight hours of lectures per day, and the best poster session in the field. Not only because it is the poster session with a bar that serves local micro-brewery beer, but also because the bar keeps people at the posters and everyone, even invited speakers, bring posters. Luckily it is three years to the next meeting so that I, and my liver, can recover.