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2006/11/10, 11:42 AM
I found this very interesting to say the least....and if you figure the science involved in training, it does make a world of sense.....
Hansen AK et. al. Skeletal muscle adaptation: training twice every second day vs. training once daily. J Appl Physiol. 2005 Jan;98(1):93-9. Epub 2004 Sep 10.
Low muscle glycogen content has been demonstrated to enhance transcription of a number of genes involved in training adaptation. These results made us speculate that training at a low muscle glycogen content would enhance training adaptation. We therefore performed a study in which seven healthy untrained men performed knee extensor exercise with one leg trained in a low-glycogen (Low) protocol and the other leg trained at a high-glycogen (High) protocol. Both legs were trained equally regarding workload and training amount. On day 1, both legs (Low and High) were trained for 1 h followed by 2 h of rest at a fasting state, after which one leg (Low) was trained for an additional 1 h. On day 2, only one leg (High) trained for 1 h. Days 1 and 2 were repeated for 10 wk. As an effect of training, the increase in maximal workload was identical for the two legs. However, time until exhaustion at 90% was markedly more increased in the Low leg compared with the High leg. Resting muscle glycogen and the activity of the mitochondrial enzyme 3-hydroxyacyl-CoA dehydrogenase increased with training, but only significantly so in Low, whereas citrate synthase activity increased in both Low and High. There was a more pronounced increase in citrate synthase activity when Low was compared with High. In conclusion, the present study suggests that training twice every second day may be superior to daily training.
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Maximus from Gladiator....Strength and Honor!
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2006/11/10, 09:09 PM
And in laymen's terms?
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2006/11/11, 11:40 AM
They trained single leg leg extension, while training one leg in a glycogen depleted state (no carbs prior to workout) and the other leg with the same volume and intensity but in a high glycogen state.
They then proceded to change the frequency for the high and low glycogen legs, and found that there was no significant difference in maximal strength, however the low glycogen leg experianced a diminished time until exhaustion (surprise!).
They then drew the conclusion that training every second day is superior to training every day.
while interesting, there is nothing surprising here, and the study is flawed in my opinion. The conclusion does not match the introduction and hypothesis, and is not tested properly.
Secondly, the leg extension was used as a strength test. Now while I understand why this is an accepted diagnostic test, it is flawed in that it neglects one of the main reasons for supplying glycogen stores during strength training.
When doing high intensity exercise utilizing heavy compound movements (ie, exercises other than leg extensions) a high level of cortisol is produced in reaction to testosterone levels increasing. Spiking insulin is one of the easiest ways to control this, and this is done through the intake of carbohydrates.
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Iron and chalk.
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2006/11/11, 03:01 PM
The study set out to examine two different training patterns on endurance adaptations based on the idea that glycogen levels in the muscle can impact on training adaptations (possibly beneficially from an endurance point of view).
The subjects each performed one legged exercise but each leg was subjected to a different training pattern over a 10 week period. One leg was trained twice per day (but only every other day) with a 2 hour break in between workouts; the other leg trained once daily. The results for a given subject between legs were compared.
Thus, the twice per day leg was being trained in a relative state of glycogen depletion (subjects were not allowed to eat between workouts) while the once/day leg was not (as glycogen would have been replenished between workouts).
The increase in maximum power was identical in both groups. However, the twice/day group doubled their endurance at 90% of maximum power compared to the once/day training group. One enzyme of aerobic metabolism was significantly increased in the twice/day group as well.
Given that muscle glycogen (and specifically low muscle glycogen) has been shown to increase the activation of a cellular energy sensor called AMPk (adenosine monophosphate kinase), these results are not terribly surprising.
As an interesting tangent, examination of the Kenyan runners find that they typically do an easy run at 6am followed by a harder run at 10am, often with a third run in the evening. Could the short period of time between their two workouts be causing an effect similar to this study?
From a practical standpoint, it's doubtful that most athletes would be able to put two workouts that close together (with only a 2 hour break), a more typical two/day training pattern would be a morning and afternoon session or a lunch time/evening pattern. Of course, the same level of glycogen depletion could be generated by limiting carbs between the two workouts (to maintain a lower level of muscle glycogen).
As an additional effect, that was not examined mind you, I might also suggest that this pattern (training twice/day but every other day) might allow for better overall recovery from training. That is, training three days/week but twice/each day gives more total days off than training 6 days/week but once/day. Individual days are harder but overall recovery seems to be better.
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Maximus from Gladiator....Strength and Honor!
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2006/11/13, 10:21 PM
i'm no body builder, but as far as science goes, this study doesn't seem to be a very good one. maybe i'm reading incorrectly, but it seems to me they're using 2 different variables simulataneously (glycogen levels and training pattern). this would make it impossible to scientifically claim the end results because you can't directly point at just one variable being the determining factor.
it's like saying "we wanted to see if eating at mcdonalds will make you run slower, so we had one guy eat a big mac, and the other guy had no big mac and also didn't wear shoes."
you can't draw conclusions from that sort of data. again tho, i'm no body builder or chemist so maybe i'm missing something.
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2006/11/14, 09:22 AM
I'm sure they'll do more studies on this topic. It is a well-known fact now that environmental factors are involved in how our genes are transcribed. Do a search on 'epigenetics' and you'll see. Studies like these are showing that you can overcome some genetic limitations by changing diet and behavior.
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--JBennett
"I've up-ed my intensity.... now up yours!"
"Pain is only weakness leaving the body."
"Never think of how weak you are; think of how strong you're going to be."
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