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Old 01-03-2009, 06:27 PM   #11
Chris H Laing
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Originally Posted by Darryl Shaw View Post
Protein requirements for athletes are 1.2 - 1.8g/kg/day (about double the RDA) regardless of whether you're a runner or a lifter.
I disagree. The nutrition of an elite marathon runner differs greatly from that of an elite weightlifter.

LSD runners are all about the carbs to keep glycogen stores high for their super long endurance workouts, and oly lifters eat buttloads of protein and fat, and cycle their carbs to help restore glycogen, but stay low carb for the majority of the time.

This is also extremely simplified, and I'm not really sure why it is like it is other than what I already said, but if it works, it works, and high protein/fat, cyclic low carb has been proven again and again to work for oly lifters, while high carb has been proven detrimental.
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Old 01-05-2009, 05:50 AM   #12
Darryl Shaw
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Generally speaking runners eat too many carbs and not enough protein and lifters eat too much protein and not enough carbs however for the reasons I gave earlier their nutritional requirements are actually very similar.

As for a high protein/fat, cyclic low carb diet being "proven again and again to work for oly lifters" well, I'm sorry but it's just an unproven hypothesis with very little supporting evidence, in fact evidence from studies subject to peer review suggests that athletes perform better when they're eating enough carbs to replenish glycogen stores between workouts; something which is almost impossible to achieve on a low carb diet.

The Effect of Carbohydrates and Fats on 24 Hour Nitrogen Balance
As has been discussed, energy has a tremendous nitrogen sparing effect [34]. However, a related topic concerns the differential effects of fats and carbohydrates on nitrogen balance. In this context, McCarger [83] investigated the effects of a high carbohydrate or high fat diet on nitrogen retention, substrate utilization, and serum hormone concentrations in six healthy male participants. The diets were administered at maintenance and at 75% of maintenance calories. Results indicated that the high fat diet produced slightly greater nitrogen retention in the 75% restricted diet than the high carbohydrate diet, while no differences existed between diets at maintenance. Results such as this have led Millward to suggest that "for now energy intakes can be considered independently from the composition of that energy as determinants of NB, thus simplifying the issue [34]." However, these results need to be replicated; particularly, in the context of exercise training.

Carbohydrates and Fats in Resistance training exercise
While carbohydrates and fats may spare nitrogen in a similar manner, it is important to recognize that carbohydrates are critical for high intensity exercise. As an illustration Jacobs et al. [84] investigated the effect of depleting muscle fibers of glycogen on strength levels. It was found that glycogen depletion in both fast and slow fiber types in the vastus lateralis was associated with impaired maximal muscular strength produced during a single dynamic contraction, as well as with increased muscle fatigue patterns. Further, it has been well established that a decrease in intensity can cause a significant loss of adaptation [43,85-88]. These results suggest that a decrease in carbohydrates may indirectly decrease muscle tissue, or impair further adaptations.

Interaction between carbohydrates and protein/amino acid intake
Koopman and colleagues [89] investigated the effects of carbohydrate (0.3 g per kg-per hour) (CHO), carbohydrate and protein (0.2 g per kg-h) (CHO-PRO) and carbohydrates, protein and leucine (0.1 g per kg-h) (CHO-PROL) on net protein balance, and amino acid oxidation rates. Results indicated that net balance was negative in the CHO condition, and positive in the CHO-PRO and CHO-PROL conditions, with the latter attaining the highest values. These results paralleled plasma insulin concentrations, with insulin being highest in the CHO-PROL condition, intermediate in the CHO-PRO condition, and lowest in the CHO condition. The net balance was improved through increased protein synthesis and decreased protein breakdown in the CHO-PROL condition relative to the other two conditions. Further protein oxidation was lowest in the CHO-PROL condition. The rationale may be that leucine intake enhances insulin secretion [89], and independently increases protein synthesis [90,91]. It is generally thought that insulin enhances protein balance through hindering protein degradation [40,92], which was supported by this study.

However, the role of insulin in stimulating protein synthesis is in debate [89]. In vitro studies [93-95] have supported insulin's role in regulating protein synthesis, while a number of in vivo studies have shown discrepancies in protein synthesis [96]. As an illustration Biolo et al. [92] found that insulin infusion increased protein synthesis at rest, but not after resistance training exercise. The authors concluded that it was the decreased amino acid availability which depressed the stimulatory effect of insulin. This was supported by Biolo et al. [97] when they found that maintained amino acid levels in the presence of hyperinsulemia increased protein synthesis. Further, Hiller and colleagues [96] suggested that discrepancies seen between in vitro studies and in vivo studies centered around plasma concentrations of insulin. To test this question, Hiller et al. [96] raised plasma insulin levels to concentrations similar to studies conducted in vitro, while maintaining amino acid concentrations. It was found that hyperinsulemia increased protein synthesis greatly. Therefore, mechanisms which enhance the insulin response to food may enhance protein accretion. The efficacy of combining carbohydrates and protein on insulin secretion was demonstrated by Ivy et al. [98] who found that the combined effects of protein and a high glycemic carbohydrate were greater on stimulating insulin secretion than their independent effects.

Summary of the effect of carbohydrates and fats on protein balance
In summary it appears that both carbohydrates and proteins have similar nitrogen sparing effects [34,83]. In this context it may be advisable to increase fats when carbohydrates are lowered. However because carbohydrates are critical to athletic performance [84] the athlete should be conscious of decreased intensity and performance with decreased carbohydrate intakes. Finally, there appears to be an interaction effect between protein and carbohydrates in stimulating insulin secretion [98-100]. This latter effect may be beneficial when manipulated for protein accretion purposes.
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Old 01-12-2009, 08:29 AM   #13
Rachel Izzo
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While weightlifters definitely don't need to eat a ton of carbs, they are in NO SENSE eating a low-carb diet.

Check out Melanie Roach's diet; it's anything but low carb.

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