Carbs not Required post workout
- 12-21-2010, 01:26 PM
I must be communicating badly?
Regarding glycogen replenishment in bodybuilding. I wrote this in post #5- "Carbs aren't 'required' post workout. Glycogen levels are shown to replenish in study groups who drank just water."
Regarding time of day comment. In post #11- "Why wouldn't you take a high amount of carbs/calories post workout if you can afford it? It is the only time of the day I can take that much sugar without falling asleep afterwards." -
- 12-21-2010, 01:32 PM
12-21-2010, 03:53 PM
12-21-2010, 03:56 PM
12-21-2010, 08:38 PM
If it doesn't show the benefits on beginners, I don't expect to see anything in trained. Trained athletes are shown to have much less damage than beginners.2 trials of leg extensions on "recreationally active" participants is hardly an applicable sample size. The study was also not calorically controlled, which makes a huge difference (duh).
The study just like any other protein study is obviously calorie controlled. these acute studies are much better than long term studies where we got no clue what they ate during a 12 week period unless you give them food packets. And they all came after an over night fast too.
I have bolded my answer in your post. Resistance training is different from endurance training. I don't see to much glycogen getting depleted unless you are doing lot of volume and high rep sets.The point of post workout carbs is for the resynthesis of glycogen, not to blunt protein degradation. Several studies have shown the benefit of adding protein To pwo carbs following endurance training leads to faster recovery of glycogen and reduced protein degradation than carbs alone.
And just so that people know glycogen do not build muscle unless it does something to protein synthesis or protein breakdown.
Only thing I can see problematic is they only did 4 sets of 12. In real world most people, do a lot more sets for legs. There was a study which showed 9 sets of 12 depleted 36 % of muscle glycogen.
12-21-2010, 09:04 PM
M.Ed. Ex Phys
12-21-2010, 09:28 PM
"Participants were asked to refrain from heavy leg exercise for 72 h prior to each of the trials, and to refrain from alcohol, caffeine, and other drugs for 24 h prior to each of the trials. Participants kept a food record for the day before their first trial and were asked to replicate the diet and approximate eating times before the second trial. Participants were only permitted to consume water during the 10h before each trial, and they were asked to obtain a full night of sleep on the evenings before each trial."
And what has long term study got to do with the sample size n?
And read it again what I wrote: I meant you cannot completely control someones diet in long term study unless you are feeding them food packets or lock them up in a building which is usually a problem with body composition studies.
12-21-2010, 09:50 PM
M.Ed. Ex Phys
12-21-2010, 10:16 PM
This study is cross over design. you do one sets of measurements and the next time after a washout period you do the other one.Within subjects designs like these eliminate problems with genetics and motivation factors since you are using the same subjects.
The sample size is determined by a power analysis before the study (which they did). You need just enough sample to see if you can find a significant difference. You can make any difference statistically significant, if you have a high enough sample size. So more doesn't mean good.
12-21-2010, 10:25 PM
If you can't understand why n should be large, then you should stop making making broad conclusions on a given study. Understanding n is covered on the first day of any decent experimental design class, which I gather you have never taken.
M.Ed. Ex Phys
12-21-2010, 10:36 PM
Second, where did i say more n do not mean more statistical power. Read my post again.
You can make even a 5 lb difference in strength statistically significant if you have a large sample size. So the goal of a study is not find the LARGEST sample size, but just enough to have it significant to prove that there is a meaningful difference.
And no reason start being condescending in your posts.
12-21-2010, 10:49 PM
For example: if you have a test group of 10 and 4 show an improvement, then that is an impressive statistic; however, if you expand the sample size to 100 and only 13 show improvement, then it is not nearly as effective or as high of a ratio. Why else do you think there are 1000's of trials done on medications? You want to weed out the data and find out if you can reject the null hypothesis or if the p-value is too high to reject the null hypothesis.
M.Ed. Ex Phys
12-21-2010, 11:03 PM
Have you heard about power analysis?
Here is the definition for it: Power analysis can be used to calculate the minimum sample size required to accept the outcome of a statistical test with a particular level of confidence.
I hope you understand that it is SINGLE study and by "trial" means the 2 separate groups for carbs and carbs +protein.
12-21-2010, 11:54 PM
Your not understanding the definition of statistical power, and reading the definition on wikipedia doesn't do your argument justice. Statistical power is basically how much you can rely on a statistical test to support or reject the hypothesis. It is related to sample size, and the larger the sample size (n), the more statistical power you have. You don't want to have the minimum sample size needed to Accept an outcome, you want the largest sample size possible to maximize validity.
This is the only study I've been able to locate looking at this matter. one study involving 13 recreational subjects performing considerably less volume than most on this website, is not enough to make the claim that post workout carbs aren't needed after weight training. But it does spark interesting debates, and opens the door formmore research,'so it's still a good post.
12-22-2010, 12:42 AM
Restoring muscle glycogen is important only when doing endurance events. Normal eating will restore glycogen for regular weight workouts. If you need to carbo-load before a bodybuilding contest, for example, to look as cut as possible you would then carbo-load. But this is not a recommended practice for normal weight workouts.
One of the belief is that carbo loading or glycogen loading increases your power or maximum aerobic output. The amount of glycogen in your muscles does nothing for strength, power or V02 max. it simply enables you to continue longer at your maximum aerobic pace. Far from increasing power, for short events (less than 2 hours), glycogen loading is a definite liability. 1. There is insufficient exercise to use the extra glycogen. 2. More important, doubling your glycogen store will increase your water and glycogen weight by 4-5lbs which will reduce your performance for shorter workouts. Extra glycogen will also create tightness and stiffness of muscles. -Colgan Institute
12-22-2010, 02:29 AM
I'm not going to tear this apart too much although I disagree with almost all of it. But glycogen is the main substrate used during weight training If your doing any more than say 5 reps. Phospho-creatine can sustain the energy output for a few seconds, but then glycogen becomes the main source. I mean anyone who has tried to workout carb depleted can attest that low glycogen stores equals a sh*t workout.
Either way the argument we have is whether the use of cho immediately following exercise is beneficial, or if protein alone is enough.
I've been searching on and off and cannot find any other studies looking at this issue. The only support I can find for the use of carbs are when they are combined with protein. The other support comes from endurance based trials, which don't compare well to this population. There are studies showing that resistance training improves glucose uptake and tolerance, which may allow for faster glycogen repletion, but if your only lifting a muscle group once per week then it wouldn't matter.
I'm curious if there is a relationship between glycogen content and protein synthesis. Meaning does glycogen synthesis take priority over protein synthesis or visa versa, or is there no relation.
12-22-2010, 07:22 AM
Power analysis is HOW you find a sample size for a study. This is the basics of study design. You don't go pick up a random large number. This is because MINIMUM number of people you need depend on the alpha level, study design and the effect size you are looking for.
They did a power analysis for their effect size and alpha level and 13 participants for a cross over design is what needed. A cross over design is a within subjects design which needs much less subjects than a between subjects design.
There are other constraints like financial and ethical concerns when you do sample size calculations. These studies are really expensive and you have to pick the minimum number of people.
The volume is less which I mentioned in my first post and is a valid point. But I don't know if it will make a difference since insulin went up almost 40% more and still nothing.
Can all the people who are so concerned about the sample size and volume, find me the PERFECT study which conclusively proved to you that carbs post workout showed greater increase in muscle?
12-22-2010, 07:47 AM
Regarding medical studies, there are 1000's, if not 10's of 1000's, of trials done to gather conclusive data about the efficacy of the drug. The greater the population is represented in the data, the greater the chance it can be applied.
Honestly, does 13 people doing 2 trials of leg extensions mean anything? No. It is a step, albeit a baby one, in the right direction, but nothing of merit can be extrapolated from this data.
M.Ed. Ex Phys
12-22-2010, 07:59 AM
Leg extensions is the perfect exercise for studies like this. It's an isolation exercise and can target the muscle and have less problems with skill levels.
And please do not go back to his more the better. There is more to sample size than "more is better".
12-22-2010, 08:12 AM
12-22-2010, 08:26 AM
And you don't understand this fieid hence. Phillips is one of the top exercise researchers who has been doing these type of studies. They know a bit of study design and sample size.
12-22-2010, 08:29 AM
12-22-2010, 08:32 AM
The external validity of this study is this: after an acute bout of leg extensions in untrained subjects, carbohydrates do not enhance protein syntehsis any more than protein alone. Thats it.
You cannot extrapolate the results to anything greater than that without making infferential leaps of faith. Hence, why at the end of any discussion, the researchers will say " we found xxxx, however, more research is needed to see if xxxx will result in xxxxx"
12-22-2010, 08:36 AM
It is different having a hypothesis and way different proving that hypothesis. I haven't come across any which tested specifically the hypothesis of requirement of carbs. I will wait for your references.
12-22-2010, 08:45 AM
The hypothesis proposed by researchers are very narrow and direct. In the case of the aforementioned study, it was a few biochemical processes that are involved in protein synthesis right after resistance training.
We forget a few things wrt to hypertrophy.
1. Protein synthesis is an ongoing process, not just an hour or two pwo.
2. The synthesis of new myofibrils only makes up a part of hypertrophy, thus,
3. Sarcoplasmic hypertrophy - the merging of satellite cells and the hormones inolved in signalling this (IGF, MGF, etc.) - must also be taken into account attempting to talk about post workout CHO and hypertophy.
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