"Never be limited by other people's limited imaginations. If you adopt their attitudes, then the possibility won't exist because you'll have already shut it out." -Mae Jemison, astronaut

Wednesday, June 25, 2014

Research Musings: Acidic Blood, The 80:20 Rule, and Heat Acclimation Tactics

Here are three I was reading up on lately.

(1) The Alkaline Forming Diet/Alkaline vs Acidic Food Claims

Admittedly, I didn't do too much research on this one, because I did research and blog it here at the end of 2012. But it reared its head again with some YouTube and Facebook posts, so I went out to check whether there had been any changes to the science on this one.
The pH of gastric acid (which includes hydrochloric acid): 1.5 - 3.5

Nope. As I wrote in 2012, your pH is tightly regulated by your body. The pH of your urine can vary, but this has nothing to do with the pH of your body. In fact, changes in your urine are totally normal, as the body does its normal job of filtering through your lungs, kidneys, and liver, and no matter how acidic or alkaline your food is, "it is not going to get near your bloodstream in anything like its original chemical form." If you skip out on so-called acidic foods, which include meat, dairy, and grains (a pretty big part of a human diet), you could miss out on important nutrients and essential fatty acids your body needs.

(2) The 80:20 Rule

In 2010, after a couple good race results, a few very wise elite runners gave me some advice - without my even asking :) There I was, enjoying my successes and feeling pretty happy and there they were saying, "Yeah, you've done all right, but if you really want to be the best you can be, you should be doing speed work."

Speed work?!? That's for 10k runners. Maybe even marathon runners. Not an ultra runner!

I started doing that dreadful speed stuff, adjusting my training programs accordingly. And the results, of course, have proven them right.

But how much speed work and when? Well, I definitely ascribe to the "hard day/easy day" philosophy. Never two hard days in a row, as that increases injury risk due to lack of recovery. In many ways, we get stronger during our recovery time. No recovery time, no improvements - injury awaits. This means I wouldn't run two really long runs back-to-back, either, as a long run (say 5-8 hours for me), edges into a "hard" day, even though it's not a speed day. I learned this one rather the hard way, trying to follow those crazy generic online programs that have us running 3 and 4 hour back-to-back sessions, week after week. My body couldn't take that kind of load. (But guess what? Dropping back the mileage to what my body could tolerate, I could still do all those races!)

I also don't do speed work when I'm building volume. Another running philosophy with merit, I think: Don't do two things at once. Building volume and speed at the same time doesn't allow for sufficient recovery - therefore putting us at increased injury risk. That song by The Byrds comes to mind:

To everything, turn turn turn
There is a season, turn turn turn
And a time for every purpose under heaven
A time to build up, A time to break down...
A time to gain, A time to lose...
Business loves the 80:20 Rule, too. Human nature to create even numbers & rules!

Recently, a runner asked me about the 80:20 Rule - being that one should do 80% of runs at less than 75% of max HR, leaving 20% of runs as speed work (tempo/interval).

I had to admit that I hadn't really heard of this. In my head, I had jumped long ago onto programs advocating closer to a 90:10 mix. But once I started looking, I found there was quite a body of stuff out there on this "80:20" concept. But it's looking to me that this "rule" has been applied to endurance athletes as a whole. That is, they are lumping together runners, swimmers, cyclists, and cross-country skiers. Seiler (and Seiler and Tonnessen) found that most "highly trained athletes" were doing about 2 speed sessions per week. However, those athletes are also doing 10-13 sessions per week. For elite male runners, typically doing 160km/week or more at a 4 min/k average, that would equate to 10-12 or more hours per week of total running. The time spent in two speed sessions might total 1.5 hours (say an interval session one day and a tempo another day). That yields something like 1.5/10-12hrs (or more), which is 12.5 - 15%. Even if we look at it on a mileage basis, we're talking about a max of 20km of speed out of 160km or more of total running, which is 12.5%.

Indeed, the authors above noted that the few elite runners they specifically questioned were doing 85% of their runs at easy pace.

So, the 80:20 "Rule" sounds like it's being applied erroneously to runners. Humans like nice, neat packages and catchy phrases. But when I do the maths for runners and read the data on runners in these studies, I'm reading 85:15 Rule or 87.5:12.5 Rule. But those ratios don't roll off the tongue so nicely ;)
But for runners, the 80:20 Rule could cause this ratio, too!

The authors note that running "imposes severe ballistic loading stress that is not present in cycling or swimming..." and that there is a "strong inverse relationship between tolerated training volume and degree of eccentric or ballistic stress of the sport." This seems to back up the reason why runners AREN'T doing 20% speed work.

And let's remember that this 80:20 Rule, which in reality appears to be an 85:15 or 87.5:12.5 Rule, applies to WELL TRAINED endurance athletes. So, before going off to race around the track a couple times each week, consider where you're at in your own running development. Are you at the "well trained" level yet? I truly believe that if I'd hit speed work much earlier than I did, the extra stresses on my body would have likely broken me - unless I'd really dropped some volume, at least.

(3) Heat Acclimation or Acclimatisation

I didn't want to get too caught up in terminology here, but whilst some writers seem to use either term to mean the same thing, I understand acclimatisation to mean our natural adjustment to our natural surroundings, whereas "acclimation" is a forced (i.e., "un"natural) way of trying to achieve acclimatisation. Thus, going outside on a hot day and running is a natural way of "acclimatising" yourself to heat, but piling on layers of clothes and getting into a sauna is an "acclimation" technique for acclimatising. Right. Moving on.

It's perhaps the wrong time of year in Australia to be talking about heat acclimatisation, but for those in the northern hemisphere, just coming out of a long winter, or those in the south who might be travelling to race, the topic would be timely. And it just happens this is the first time I've made time to blog it :)

Running in heat stresses us, as our bodies are already dealing with expelling the extra heat produced by exercise. A muscle at rest is 33-35 degrees C. When at rest, we lose heat in 4 ways - about 60% via radiation (heat just radiates out of us), 25% by evaporation (water in sweat/breath), and 15% via convection (air flowing over our skin carries away heat). There's a nominal amount that we lose by conduction (whatever we touch - like sitting on a cold bench or standing on cold ground).

When we exercise, the energy produced for the muscles produces a by-product - heat - that needs to get released from the body. Evaporation (sweat and breath) goes into the top position now for heat loss - perhaps 55% of our heat is lost this way. Convection (the breeze blowing on us) also goes up - say 35%. Radiation drops to about 10%. When the air temperature goes over 36 degrees C (remember the temperature of our resting muscles?), our bodies GAIN heat through convection and radiation. So evaporation really becomes our only way of countering this on the extreme heat days. And keep in mind that when the weather is very humid, evaporation is weaker because the water released as sweat on the skin doesn't evaporate as readily.
Easy to feel like a baking lizard on Australian summer runs!

I read a very encouraging study just before Australian summer (that is, back in Dec 2013) by Costa and colleagues who found runners showed signs of acclimation to heat within 2 exposures of 2 hours of easy running (just 60% of VO2max) at 30 degrees C. Acclimation was measured by two key changes:

(1) Cardiovascular. You can think of that as heart-blood changes. What it meant is that blood plasma volume increased. This "hypervolaemia" results in a greater stroke volume with each pump of the heart muscle. That means heart rate goes down. Lower heart rate is a good thing when running!

(2) Thermoregulatory. Temperature regulation. Sweat sensitivity increased, sweating started earlier, and sweat rate went up. (Keep in mind this means that earlier sweat rate means a heat acclimatised runner will need more fluids, not less.)

Even better, Wendt et al (2007) reported in their literature review that you only need to exercise above 50% of max (enough to sweat, essentially), that 90-100 minutes was enough to achieve change, and that you don't have to do all your training in heat, as long as you have more time. Every day for 10 days or every third day for a month yield the same physiological changes.

So, how to use this information to our advantage?
Could it just be this easy?

First, mentally, we can know that after a couple runs in hot weather, our bodies have made the major changes necessary to adapt already. There's a mental aspect that needs extra time, but I think we can augment the mental adaptation by knowing that we have physically adapted. Costa and co noted that the runners in their study did not adapt their comfort rating in the heat (finding heat more bearable), until they were exposed to more easy running and higher temperatures (35 degrees C). The authors felt "thermal comfort" took longer to develop due to changes necessary in the metabolic system (the work of the hypothalamus to connect the nervous system to the endocrine system). The hypothalamus controls things like thirst, body temperature, and circadian rhythms.

Second, when going to race somewhere hot from somewhere cold, we needn't fret excessively about spending weeks in saunas or running in layers upon layers of parkas. A couple 2hr sessions create change. However, we need to keep in mind that these adaptations will decay. Just like adaptations made when we go to altitude. Whilst short term changes to plasma volume may be gone in 72 hours, if you have acclimated over 10 days or more, you should have at least 7 days (but likely less than 14 days) before significant decay occurs. The fitter you are, the longer your acclimatisation benefits should last.

So, whilst you can "cram" before a hot race with a couple sessions of heat running, you probably can't do it a week beforehand, as the effects will decay. Either you need to acclimate longer or you need to get time in the heat at >50% VO2max right before race day. Of course, who does a 2hr taper run two days before race day? With this in mind, you might have to consider something like acclimating and then keeping up your blood thickening by doing a couple "easy" workouts in a sauna (dry-heat acclimatisation is better retained than humid-heat). Don't dehydrate yourself, though! Researchers also found that "euhydration [normal levels of hydration] is a prerequisite for optimal heal acclimation to occur." In fact, dehydration abolished the advantages of acclimatisation.

Third, you might use heat acclimation techniques to improve performance even at a cool weather race. The adaptations made by the body, including cooler core temperature, greater blood plasma, lower heart rate, and increased sweat sensitivity and sweat rate, will positively affect your race, no matter the ambient temperature.

Bikram Choudhury, the founder of the Bikram method
What about Bikram yoga as an acclimation technique? That's the hot yoga, conducted at 35-41 degrees C, involving 26 poses over a 90 minute class. I've not done one myself, as it sounds pretty yucky to me. :) There's not much research yet, but what I found suggested it won't do the trick. One study noted that HR was 57% of max during Bikram (56% of max during regular yoga). Thus, it's not really a surprise then that Tracy & Hart's 2013 study of young, healthy individuals put on an 8 week Bikram program (3 x 90 min sessions/wk) showed that Bikram did not induce cardiovascular or metabolic changes. As we learned above, exercise intensities for heat acclimation have been at 50-60% of VO2max. This is closer to 65-70% of max HR. Your "long slow distance" running pace. Abel and colleagues (2012) also found no changes in "resting hemodynamics, pulmonary function or aerobic fitness" in their study of novice versus long-standing Bikram practitioners.

But I'm sure there are other good reasons for sweating profusely in a crowded room with strangers.

No comments:

Post a Comment