Why do some people not believe in pre training stimulants?

Yes, as Dr. Dan says, these products provide a very substantial increase in energy, endurance and muscle pump for most people and have little effect or cause over-stimulation in other users. So, as with many supplements, foods, drugs, training programs, there is an aspect of "individuality" - this is one of those categories of supplements in which there is a fairly wide variety of response.

Some stimulants have been shown to blunt insulin sensitivity. Others (adderal, amphetamine) are strongly catabolic to muscle tissue. Either way, this is not conducive to a lean, muscular physique.

Personally I like a stong green tea as my main 'stim'. The EGCG in it also inhibits fat cells from lipogenesis and also acts as a form of glucose transporter into muscle cells, via the enzyme phosphatidylinositol (PI) 3-kinase.

You don't actually want insulin sensitivity to increase before training (as insulin removes blood sugar, which is the body's energy fuel. A lot of companies make the mistake of adding lipoic acid or cinnamon extracts or other "insulin sensitisers" to their pre-workouts and this is such an obvious mistake (or maybe it's just obvious to me!?!?).

Green tea does increase insulin sensitivity but it is also a research-proven performance enhancer and fat burner and also has effects via caffeine (you need 4 or 5 cups for this to work well though). So there's something going on with green tea that overcomes the negative effects of increased insulin sensitivity on workouts.

I cannot recommend supplements to my patients because of the high risk of a supplement potentially interacting with one of the 10 medications many of my patients are taking or negatively affect one of their health conditions. If you are taking a medication regularly, please check with your pharmacist to make sure that the supplement, when taken doesn't cause any adverse side effects.

All of my training and the research I currently do over and over again supports that if you let it, the body naturally adapts to the exercise stress, resulting in positive health outcomes and an appropriate physiologic response. So while I am sure that there are situations where supplementing can be beneficial, I have the philosophy that if it ain't broke, don't fix it and would not recommend that the average person in the gym looking to improve their health and loose a little weight utilize supplements.

Mark: I kind of agree with you on the insulin sensitivity before training (though it's much more complex an issue than you make out, since some people desire that their workout energy comes from FFAs, not BG. If BG is elevated as you seem to advocate, then so will insulin be elevated, reducing the degree of lypolysis), however I was referring to the long-term effects of reduced insulin sensitivity on health and performance, not the peri-workout effects.

In the long term, it is essential to have excellent insulin sensitivity, to reap the physique improvments from efficient nutrient partitioning. EGCG may help with this as may cinnamon and some glucose dispersal agents, such as ALA etc. So their use os more of a long-term approach IMO.

Sorry for any misunderstanding.

Hi Alex,

During training, epinephrine, cortisol and glucagon are more prevalent and that situation exists because it leads to more sugar (blood sugar / BS) being available for fuel - there's a fine line between trying to access more fatty acids during training and going hypoglycemic - so the body isn't likely to secrete extra insulin during exercise. So if an insulin sensitiser was taken, it might lead to low availability of blood sugar and energy deficit.

There is also some evidence that very heavy resistance training impairs insulin sensitivity (whilst less intense activity has the opposite effect). Lipoic acid specifically, is able to "repair" some of the negative effects on insulin from heavy lifting.

So in my personal opinion, I would save the insulin sensitisers (except for green tea) for after training and other times throughout the day - especially with high-carb meals.

Thanks Mark, for the response. I would say however that blood hormone levels vary significantly with the type of training (LISS Vs anerobic, etc) and the type of pre-workout nutrition the athlete chooses to consume.

Of course the body won't likely release insulin during training, but it is entirely possible for insulin that is released immediately pre-training, to still be active in the blood stream, especially if the insulin is exogenous.

Glucagon is secreted in response to low blood sugar, so is unlikely to be secreted during a short anerobic resistance training session IMO. Of course, a LISS session will create a different hormonal climate, much as you describe.

Yes, cortisol can be secreted (and over-secreted in some situations) during training and has been shown to exert a temporary negative effect on insulin sensitivity, just as many catacholamines (exogenous, such as geranamine) do. This is why I utilise a carbless PWO approach and have most of my athletes do so.

Thanks for the debate :)

When we start an exercise bout, catecholamines are released, which contribute to the resulting elevated heart rate and blood pressure during exercise; the more intense (i.e. the more anaerobic) an exercise bout, the greater catecholamine response. In addition, epinephrine stimulates glycogenolysis, the creation of glucose (i.e. sugar) in the liver and active muscles. Because our working muscles require additional glucose to do the work we’re asked of it, the GLUT-4 receptors in the muscle tissue are activated during exercise by increased muscle contractions to allow for additional glucose to enter the muscle cells and be metabolized for energy. To maintain adequate blood glucose levels with increased glucose transport into the muscle, blood insulin levels drop during prolonged exercise.

Therefore, exercise has an insulin-like effect on blood glucose levels. That is, the active muscle contractions independently of insulin, cause increased glucose uptake. Diabetics who take insulin to control their blood glucose, are instructed to not inject insulin into working muscle when they are going to be exercising to prevent possible hypoglycemic conditions from occurring. Therefore, I assume that taking a supplement that made the body more sensitive to insulin, during a physiologic state where there is already increased glucose uptake would increase risk of hypoglycemia and “hitting the wall”?

As individuals become more trained, their bodies rely more on fat metabolism than glucose metabolism. This is a normal training adaptation. However, without glucose, incomplete fat metabolism occurs, resulting in the production of ketones and increasing risk of ketoacidosis. In addition, during anaerobic activity, our body depends on ATP derived from carbohydrates (ATP-PC and glycolysis). And our brains rely solely on glucose. So carbohydrates are really not our enemy.

What I struggle to understand is why there is such a tremendous focus in the fitness community on increasing fat metabolism. It is already well established that increased fat metabolism does not result in increased weight loss. Weight loss, and fat loss that accompanies weight loss, is solely the result of creating a caloric deficit. And as I mentioned previously, trained individuals depend more on fat metabolism when exercising, which is why high fit individuals can exercise for longer durations at any given intensity. Could someone perhaps shed some light on this? Is there something that I have missed?

.... Or should this be asked as its own question??