Showing posts with label running. Show all posts
Showing posts with label running. Show all posts

Tuesday, June 17, 2014

Crampy? Yeah Me Too

Crampy? Yeah, me too new

Written by: Dan Empfield at Slowtwitch
Date: Mon Jun 16 2014
Deadspin featured a mostly fun but partly serious and thoroughly entertaining piece in exercise-induced cramping, prompted by LeBron James’s muscular malfunction during one of the recent NBA playoff games. The piece was called Everything You Know About Cramps Is Wrong, And Gatorade Is Full Of Shit. I admit a vicarious schadenfreudish peace washed over me as I read about a corporate titan brought low. (We had a 52-post thread on LeBron’s cramps.)

But in Gatorade’s defense, it’s caught in a bind. It cannot sell the perfect sports drink for exercise in convenience stores. That drink would not taste good enough to be sold at retail to those reaching for a sports drink to wash down Spicy Nacho Doritos (cornerstone of the lunch of champions – the formercornerstone, ideally).

Some months back I was rounding into pretty good running shape. Then, 4 miles into an 8 mile loop, my calf seized. And I mean exactly 4 miles in, so that I had to get back exactly 4 miles on that calf, which did the calf no good. I tried everything. Stretching. Walking. Waiting it out. That camp would not unseize. Further, for the next 6 weeks I was “crampy.” I cramped swimming. I cramped walking around the house. I woke up crampy. It was not just in my calf, I was crampy systemically.
Cramps are a mystery, and I can’t prove it but I suspect cramps are the proximate cause of a number of other injuries. I wonder whether a lot of trunk and torso related strains – high hamstring, psoas, hip flexors – might not occur because of a cramp during exercise that we play through, that spasm exerting extra tension on the connective tissue.

There are too many glib, single-etiology responses by those who think they have the answer to why we cramp. If you go on our reader forum cramping is caused by under-hydrating. No, it’s caused by over-hydrating. No, you cramped because you trained or raced beyond your capacity. No, cramping is mental.

How do we not cramp? “Train more, race smarter,” according to one Slowtwitcher. Compression gear. Salt tablets. Electrolyte replacement (no, not that brand, this brand!)

I’m sensitive to the argument that cramping occurs because my gaze, athletically, exceeded my grasp. I just didn’t pace correctly. Fine. I’m certain I’m guilty as charged. Circling back to my 8-mile run, however, this was a standard run. I’d done this same run a dozen times over the past 2 months, no problem, and, if it were a problem, why 4 miles in, when I was still relatively fresh? Further I wasn’t putting out any effort when sleeping, so, why was I waking up crampy? And why was this crampiness systemic, rather than specific to the muscles I’d been using?
The only logical interpretation is that I lacked something, that whatever it was, magnesium, calcium, the “low fuel” light on the dashboard only registered when I got that stubborn cramp.

It seemed to me that two things might be happening. First, I might just not be getting enough of something. Second, that something else I’m doing might be blocking the availability of a required substance, or increasing that substance’s evacuation. I’m not an alcohol drinker, but I am a coffee drinker. Many studies over decades have demonstrated that caffeine increases urinary excretion of Ca and Mg in the hours following caffeine intake, not just because of a diuretic response, but because caffeine inhibits the resorption of these electrolytes.

I began to suspect magnesium, because this is the one electrolyte that seems not to occur in a lot of what I normally eat (very little magnesium in Spicy Nacho Doritos).

Two more things to mention. I have in the past had some heart arrhythmia, specifically atrial fibrillation, and this is the reason I pretty much stopped all alcohol (it was a trigger for me). Notable, however, is that magnesium supplementation was not found the decrease A-Fib (Frick, et al. The effect of oral magnesium, alone or as an adjuvant to sotalol, after cardioversion in patients with persistent atrial fibrillation. Eur Heart J. 2000).

Finally, I’m 57 years old. Age seems to be a factor in cramping. At least in calf cramping. We have a large cohort of readers that report this, and we’ve identified, named and written extensively over the past 15 years about what we call “Mad Calf Disease,” specifically targeting men over 40 in, at least anecdotally, much higher numbers than other cohorts.
My best guess was a deficiency. However, a number of studies have failed to demonstrate that magnesium (for one) supplementation increases performance. Terblanche, Noakes, et al, their 1992 paper says it all in the title: Failure of magnesium supplementation to influence marathon running performance or recovery in magnesium-replete subjects. (Int J Sports Nutr). But a year later Dragani, et al, published: Clinical, haematological and neurophysical evidence of muscle damage from magnesium deficiency in athletes: a case report. In: Golf (Magnesium Research. London: John Libbey Company, 1993).

In 2010 it was found that magnesium supplementation raised glucose levels and attenuated lactate levels during swimming. In gerbils. (Shiu-Min Cheng, et al, Eur J. Applied P). I didn’t know gerbils could swim. Apparently so.

Buchman, et al, found that “Serum and urinary magnesium concentrations decrease during endurance running, consistent with the possibility of magnesium deficiency” in “The effect of a marathon run on plasma and urine mineral and metal concentrations” (J Am Coll Nutr. 1998 Apr).
It seemed to me, reading these and other papers, that supplementation does not help you if you are not magnesium deficient. It only helps if you are already near or at the border of a deficiency.

There is a broad range of thought on what constitutes an appropriate amount of magnesium. Much of the literature has coalesced around 6mg/kg per day, which seems pretty high, but that’s a number that I keep reading. Further, it’s been suggested in the literature that athletes who train like we do bump this up by, say, 15 or 20 percent, not only because of the increased utilization of magnesium but because it’s present in sweat. Also, the FDA and others suggest upping Magnesium intake as you age. All this would put me at or near 600mg/day, much higher than the typical minimum daily requirements, and all this probably assumes that I’m not cannibalizing or sabotaging that intake through bad habits like too much coffee.

How does this comport with typical daily intakes? A large cohort in France, in a study done about a decade ago, showed a mean magnesium intake of 369 and 280mg/day, respectively, for men and women. In an “Update on the relationship between magnesium and exercise” (Nielsen, Kukaski, USDA, Magnesium Research. Volume 19, Number 3, 180-9, September 2006), “Based on dietary surveys and recent human experiments, a magnesium intake less than 260 mg/day for male and 220 mg/day for female athletes may result in a magnesium-deficient status. Marginal magnesium deficiency has been shown to impair performance and amplify the negative consequences of strenuous exercise. Thus, magnesium supplementation or increased dietary intake of magnesium could be beneficial to physically active individuals with a low or deficient magnesium status.”
So, based on the above, it would seem to me that 300mg to 350mg/day is an absolute floor for me, and closer to 600mg/day would be safer.

Are you a meat and potatoes guy? If you eat pork or lamb, along with potatoes, cauliflower, sauteed carrots, maybe some grilled mushrooms, tomatoes and cucumbers in your iceberg lettuce salad, eggs, butter and milk for breakfast along with croissants, white rice instead of potatoes now and then, congratulations. You got full and you ate heartily. But you got very little magnesium. This has been my problem, I think. You can add almost all fruit to the above list.

On the flip side: Most nuts, shellfish, green leafy vegetables (replace iceberg lettuce with romaine or, better yet, spinach), and whole grains (no more white bread or white rice), then you have a lot of magnesium. Beef is higher in magnesium than pork (beef will kill you in different ways). Chicken is also higher. Avocados, bananas, raisins aren’t bad. Salmon, tuna and mackerel aren’t bad. Of course you get way above your daily allotment for mercury, but that’s another matter.

Why don’t I just take magnesium supplements? Magnesium citrate? Yes, I could. I would not fault anyone who does. And I might still. Bear in mind that the NIH notes that the upper tolerable levels of magnesium supplementation are 350mg/day (that’s not total intake, but supplementation). That said, it seems to be fairly hard to overdo magnesium. Still, if I can get it in the sorts of foods I ought to be eating anyway, I just like that idea better.
A half-cup of pumpkin seeds gives you 600mg. But you’re not likely to eat a half-cup of pumpkin seeds. When you search the web for actual magnesium content in servings of foods you get 10g here, 6g there, and it’s easy to fall shy of 400g in a day, day in and day out, if you measure what you eat and if you eat a magnesium-poor diet. Easier still if what I really need is not 400g but closer to 600g.

So, I’ve turned over a new leaf. Literally. From now on it’s mostly spinach salads and I even got a bag of baby Kale (argh!) from Costco and am including that in my spinach salads. I’m cutting down on my coffee intake. I got myself some rice bran and wheat germ and it goes onto or into a lot of what I eat. In the morning, it’s a couple of tablespoons of wheat germ in my granola (which has pumpkin seeds in it). A cup of wheat germ has 275g of magnesium. Rice bran slays everything. It’s got almost 800mg of magnesium in a cup.

I’m back up to where I left off in my running. Same 8-mile run. Same fitness level as was the case when I got super-crampy. So far, so good. We’ll see how it goes.

Tuesday, November 19, 2013

How can Mirinda Carfrae run a 2:50 marathon in Hawaii Ironman, but you can’t?

Because she’s a very fit and gifted runner and triathlete, unlike most others! Simple and true.  The blog below was written by Sami Inkinen, 4th place in the Ironman 2013 World Championships M35-39 with a sub 9hr race.  He also crushed the 2013 Eagleman 70.3 race winning the amateur race in 4hrs 5mins.

image
This could be your body at Hawaii Ironman triathlon.

However, there are a few fundamental factors that change the limits of endurance performance at the Hawaii Ironman triathlon significantly and thus make certain athletes much more likely high performers in such conditions. Having just raced at that event the 7th time and seen many write-ups about “optimal pacing in Hawaii” or “how much slower you should expect to go in Hawaii” type of articles, I thought it would be interesting to look at the very specific reasons why Hawaii is different and why race pace recommendations based on “averages” is quite useless.

Human endurance performance is limited by many factors, many of which are still debated and whether it is our brain (=the central governor theory) or our failing peripheral muscles (=the cardiovascular model) that slows us down to our maximum sustainable speed. However, it is widely agreed that extreme heat and humidity negatively affect performance at maximum efforts. Interestingly, heat and humidity doesn’t slow down much if at all in the swim and bike portion of triathlon, which I’ve personally experienced and race simulation research in heat shows that too. So something different happens during the run.

Our bodies and brain try to avoid the destiny of eggs on a hot frying pan and there are two key factors pushing us away and towards this homeostasis while running:
    image
    Wasted heat production (in watts) at certain marathon running paces for athletes of different sizes (weight, kg). Assumes that heat power equals 80% of the total energy metabolized for the movement.
  1. Heating power that is the result of our human inefficiency. For every 1000kcal we metabolize, we only use about 200kcal (or 20%) to the forward moving motion. The rest is wasted as heat. (Roughly the same applies to cycling too, a cyclist pushing a bicycle forward at 300 watts is actually generating more than 900W of heat in addition to that forward moving power) Interestingly the energy cost of running is independent of our running pace. It takes about 1kCal per body kg to run 1km, regardless of running pace or body size. The consequence of this is that the heating power rapidly increases as you run faster and as you add weight.
    As an example, a 50kg person running a 2:50 marathon “only” needs to get rid of 750Watts of continuous heating. Meanwhile, a 65kg person can only run a 3:40 marathon at the same waste heat level. Fortunately, our bodies can get rid of some of the excess heat, so heat doesn’t always become the performance limiter.
  2. Cooling power that is primarily a function of convectional cooling and sweat evaporation (not just sweating) from skin. Unfortunately cooling power does not increase at the same rate with excess heat production, as cooling is more closely related to human skin surface area than weight. Secondly, cooling is also very sensitive to ambient temperature and humidity.

    So the bad news is that at some running speed, runners should theoretically hit the point at which heating power exceeds cooling power, (soon) after which our bodies either shut down or turn into eggs on a frying pan. This almost never happens in cycling - unless climbing a very steep hill at walking/running pace - because at 20-40mph speed the cooling effect easily exceeds the extra heat generated.
The best approximate for body cooling during running I could find was in Tim Noake’s Lore of Running, in the following chart, which seems to assume strong air flow at max running speeds (about 5min/mile) and large skin surface area (about 75kg athlete).

image

Considering the average weather in Kona, HI in October is 29.4C and 84% humidity and stays at a remarkable narrow band over the years, I estimated what happens if you run at 2:50 marathon pace in these conditions by using Noakes’ cooling model and adjusting it based on body size (skin area):


image

 It looks like a 55-60kg (120-130lbs) runner is not going to be limited by heat for a 2:50 marathon, but anyone larger than that will suffer and overheat at that pace based on average athlete’s heat loss (cooling ability).

So the obvious question is how fast can a runner of size X run in the Kona, HI conditions. Based on the above assumptions and also including a +8% heat acclimatization factor that has been show at least in some studies,  I came up with the following:
image
Estimated best possible marathon performance in Hawaii Ironman based on heat as the limiting factor for different size runners.
 
From the above chart, if you dream of running a sub 3hr marathon in Hawaii, you shouldn’t be larger than about 72kg (or 160 pounds). For reference, the 2:50 marathon women’s record holder weighs about 52-53kg and many of the top men in the 60-65kg range for this event.
So what’s the take-away for someone racing in Hawaii Ironman and hoping to run really fast?
  1. Unless you’re very small (under 55-60kg) heat is likely going to be a significant performance limiter on the marathon run (not bike or swim) assuming you’re well trained to run fast otherwise.
  2. Acclimatize and cool as much as you can on the run.
  3. Hope for a cool and windy day on the run.
  4. Watch someone like Mirinda Carfrae (52kg) run really fast every time despite the weather conditions in Kona.
Final note: This analysis was hacked together pretty quickly and I’m quite sure there are missed nuances and potential errors in my interpretation of research data. So use it at your own risk (and entertainment).