When training increases in volume or intensity, considerations related to total carbohydrate intake, the timing of carb intake, and the impacts of diet and training load on protein metabolism become particularly crucial, because upswings in training can deplete muscle-glycogen stores and throw athletes into a state of "negative nitrogen balance," in which they are losing more protein than they are making. To see what sort of nutritional strategy might be best for athletes who are undergoing an increase in total training load and who want to max-out muscle glycogen and stay positive with protein, Mark Tarnopolsky and his colleagues at McMaster University in Hamilton, Ontario recently studied 10 active female athletes over two separate, one-week periods (8). The choice of female athletes as subjects was particularly appropriate, since many sports-active females have abnormally low protein (9) and total-calorie (10) intakes. Marathon

Prior to the onset of the study, all 10 women had participated regularly in some form of endurance activity; the average training load was three 45-minute workouts per week. All of the athletes were eumenorrheic, and they were tested only during the mid-follicular phases of their menstrual cycles (days four through 11). Average VO2max, measured during progressive cycling to fatigue, was 46.3 ml/kg-min.

The athletes completed two separate seven-day interventions – a control trial and a post-exercise-supplementation trial. During these two trials, the athletes’ energy, carbohydrate-, and protein-intake patterns were exactly the same: The women consumed approximately 2160 calories per day and 1.4 grams of protein per kilogram of body weight per day (and thus 86 grams of protein each day). The overall composition of their diets was 58-% carbohydrate, 16-% protein, and 26-% fat.

On days one, three, and four of the seven-day trials, the women worked out in the mornings by cycling for one hour at an intensity of 65% of VO2max (about 76% of max heart rate). On day three, the women completed a second, additional one-hour workout at 37

65% VO2max in the afternoon, and on day six the athletes finished off a 90-minute exertion at the 65-% VO2max intensity. On the seventh day they didn’t rest, instead cycling for as long as possible at 75% VO2max (about 85% of maximal heart rate). Thus, the volume associated with each week’s training schedule was nearly 150% above the usual level (335 versus 135 minutes). Marathon

During the study, both the control and post-exercise-supplementation groups made use of a beverage produced by Mead-Johnson Canada Inc. which is called "Results." 66% of the calories in this quaffable came from carbohydrate, while 23% originated in protein, and 11% were derived from fat. The post-exercise-supplementation athletes imbibed "Results" immediately after their one-hour bike rides ended, while the control groups consumed the same amount of the Mead-Johnson product at breakfast, well before the bicycle exertions were undertaken. As mentioned, total energy, carbohydrate, and protein intakes were identical in the two groups; the only difference was in the timing of the "Results" ingestion.

During the study, both the control and post-exercise-supplementation groups made use of a beverage produced by Mead-Johnson Canada Inc. which is called "Results." 66% of the calories in this quaffable came from carbohydrate, while 23% originated in protein, and 11% were derived from fat. The post-exercise-supplementation athletes imbibed "Results" immediately after their one-hour bike rides ended, while the control groups consumed the same amount of the Mead-Johnson product at breakfast, well before the bicycle exertions were undertaken. As mentioned, total energy, carbohydrate, and protein intakes were identical in the two groups; the only difference was in the timing of the "Results" ingestion.

And what an impact that difference had! When the beverage called "Results" was taken right after exercise instead of at breakfast, the experimental results were significantly different for a wide range of variables, including fat oxidation, carbohydrate concentrations, protein breakdown, exercise capacity, and body weight! As you might expect, carbohydrate breakdown tended to be greater during workouts when the extra carbohydrate (from "Results") was taken in the morning, before the workout, rather than after the training session. Also not surprisingly, fat oxidation was greater during exercise when "Results" intake was postponed until after a workout was over. These findings are simple to explain: When athletes take in extra carbohydrate at breakfast, their liver and muscle stores of glycogen tend to rise, and thus they have more carbohydrate fuel available for prolonged exercise later in the day. When carbohydrate intake prior to exercise is more minimal, fat is forced to supply more of the energy needed for long exertion.

The key results, though, related to nitrogen balance, body mass, and performance. When "Results" was taken in after exercise rather than at breakfast, nitrogen balance was positive, which simply means that the athletes were taking in more nitrogen than they were losing (which is another way of saying that their protein stores were increasing). When "Results" was taken at breakfast, on the other hand, nitrogen balance during the heavy training was negative (protein was being lost). In addition to saving protein, drinking "Results" right after workouts also prevented excessive losses in body weight during the heavy training. When "Results" was quaffed after training sessions, the athletes lost 1.5 pounds during the seven-day period of extended training, but when "Results" was just a breakfast potable the loss in mass totaled 3.1 pounds, a statistically significant difference. Last (but not least), use of "Results" after workouts - rather than at breakfast - allowed the athletes to exercise an average of 47-% longer (!) during the 75-% VO2max effort which took place on day seven. As you take in these results, again remember that the athletes were eating the same amount and type of food during the two different trials; the only difference was the timing of the "Results" guzzling! Marathon

The key results, though, related to nitrogen balance, body mass, and performance. When "Results" was taken in after exercise rather than at breakfast, nitrogen balance was positive, which simply means that the athletes were taking in more nitrogen than they were losing (which is another way of saying that their protein stores were increasing). When "Results" was taken at breakfast, on the other hand, nitrogen balance during the heavy training was negative (protein was being lost). In addition to saving protein, drinking "Results" right after workouts also prevented excessive losses in body weight during the heavy training. When "Results" was quaffed after training sessions, the athletes lost 1.5 pounds during the seven-day period of extended training, but when "Results" was just a breakfast potable the loss in mass totaled 3.1 pounds, a statistically significant difference. Last (but not least), use of "Results" after workouts - rather than at breakfast - allowed the athletes to exercise an average of 47-% longer (!) during the 75-% VO2max effort which took place on day seven. As you take in these results, again remember that the athletes were eating the same amount and type of food during the two different trials; the only difference was the timing of the "Results" guzzling! Marathon