these are from what i believe are the 2 best write ups on pre and postworkout nutrition. the first is from alan aragaon:
PREWORKOUT
OBJECTIVE
the objective here is to promote sustained carbohydrate availability (& to a lesser degree, amino acid availability), minimize muscle catabolism, and spare glygogen as much as possible. this is best accomplished by carbs with a low to moderate GI & insulin index (II). it's important to note here that research is quite conflicting on the issue of GI & exercise performance. much of the latest studies show no real difference. nevertheless, it's established that lower-GI sources influence substrate oxidation during training ever-so-slightly better for bodybuilding purposes. when i mention GI, i'm talking about the glucose comparison standard, not the white bread standard. the actual amount & physical nature of the meal depends on how soon your schedule allows you to eat or drink before training. there are at least 3 acceptable scenarios..
COMPOSITION
scenario one: a solid, full-sized balanced meal finished 60-90 minutes preworkout consisting of 30-60g protein (0.2-0.25g/lb target BW) + 40-80g carb (0.33g/lb target BW). there are endless examples of how this can be constructed, & heres just one:
---- 5-8oz of any type of land or sea animal flesh
---- 1-2 cups low to moderate-GI grain or other starchy vegetable or legume /or/ fistsize sweet potato, etc, look up sub-70-rated examples here.
---- 1 or more cups fibrous vegetable like salad greens, broccoli, cauliflower, asparagus, spinach, kale, cabbage, onions, even carrots, etc, etc
scenario two: a liquid meal or shake finished 15-30min preworkout:
---- 20-50g protein (0.15-0.2g/lb target BW) whey is preferred for its BCAA content
---- 40-80g (0.33g/lb target BW) low-to-moderate GI carbs. any fruit works well here, so does old fashioned oats. a solid case can be built for a combination of both. whether you include water/milk or unsaturated fat like flax or pnb is really personal preference. milk just gets the anabolic/anticatabolic cascade rolling for those in a severe hurry to gain muscle. adding fat to this shake can slow the release of nutrients substantially & benefit those who train for significantly more than 90 min, offering extra protection against energy dips - especially if you don't consume a dilute carb solution during your workout. most people will do fine without the fat as long as the overall carb profile of the shake is relatively low to moderate-GI. NOTE: most commercially prepared dilute sports drink solutions have a low glycemic load, rendering their high GI irrelevant. some dudes use the same shake for pre & post workout; they make a bigass shake, and simply drink half before & half after - or they sip it thoughout the workout. this is fine too & you'll still benefit, but you're not taking full advantage of the specifically different physiologic demands of pre & postworkout for bodybuilding purposes.
scenario 3: both of the above scenarios in succession (one after the other in the above listed time frame) is probably ideal, but in the real world, many folks train first thing in the morning before work, so that nullifies the possibility of the pre-pre workout meal. no problem, that's where an intelligently concocted prebed meal helps (another topic!). note that individuals will vary in their digestive & absorptive capacity. some folks can only tolerate scenario one without the additional scenario 2 due to less gastrointestinal motility &/or speed of digestion/absorption. trial and error will dictate your optimal meal scheduling respective of this.
to reiterate the factor of individual differences, don't be afraid to go outside of the listed guidelines & exceed the upper limit of listed carb intake as needed to power you through your training. conversely, don't be afraid to dip below it given your gastrointestinal tolerance for exogenous substrate during or pretraining.
and from bryan haycock
BEFORE
Pre-workout nutritional strategies are based on providing alternative energy substrates (mainly carbohydrate) to preserve energy stores, and taking advantage of increased blood flow to muscle tissue.
Carbohydrates
High intensity exercise places great demand on glycogen stores. Glycogen is the sugar stored in the liver and muscles. Because high intensity exercise burns energy at such a high rate, the body is unable to supply sufficient oxygen to be able to use fat for fuel. Instead, it must use sugar both stored in the muscle and brought in from the blood.
Consuming simple sugars right before training can reduce the amount of glycogen used during exercise. This can prolong performance. More importantly, higher glycogen and insulin levels appears to create a hormonal milieu favorable to anabolism (growth).
During exercise, cortisol accelerates lipolysis, ketogenesis, and proteolysis (protein breakdown). This happens in order to provide additional fuel substrates for continued exercise. The effects of cortisol may also be necessary to provide an amino acid pool from which the muscle can rebuild new contractile proteins if there are insufficient amino acids delivered from the blood. This ensures that some degree of adaptation can occur regardless of the availability of dietary protein. Over time however, if this process is not balanced with additional dietary protein, the net effect will be only maintenance or even a decrease in functional muscle tissue, as is evident during periods of starvation or prolonged dieting. Fortunately, there is only a non-significant rise in cortisol levels when carbohydrates were consumed during exercise. (Tarpenning, 1998) The net effect is a more rapid increase in the cross sectional area of the muscle fibers with the greatest effect seen in type-II fibers.
This may be a less expensive option for those who were thinking of using phosphatidylserine. In this case, carbohydrate administration appears to down regulate the hypothalamic-pituitary-adrenal axis, probably through insulin or perhaps through the presence of carbohydrate itself. This would, in effect, greatly reduce the body's catabolic response to exercise stress. All good news for bodybuilders.
Protein
Another pre-workout strategy involves taking advantage of increased blood flow to working muscles. Because the availability of amino acids is often the limiting factor for protein synthesis, a pre-workout protein meal will enhance the delivery of amino acids to muscle tissue. Research has demonstrated the effectiveness of a pre-workout protein drink.
Delivery of amino acids has been shown to be significantly greater during the exercise bout when consumed pre-workout than after exercise (Tipton, 2001). There is also a significant difference in amino acid delivery in the 1st h after exercise, with the pre-exercise protein drink providing a significant advantage. Net amino acid uptake across the muscle is twice as high with a pre-workout protein drink as compared to consuming it after. Phenylalanine disappearance rate, an indicator of muscle protein synthesis from blood amino acids, was significantly higher when amino acids were taken pre-workout. These results indicate that the response of net muscle protein synthesis to consumption of a protein solution immediately before resistance exercise is greater than when the solution is consumed after exercise. This is primarily because of an increased delivery of amino acids to the muscle.
