RE: Some protein info

[Guest guest]

My main concern with some of the numbers for protein needs posted is that I am

not sure how studies on the protein needs of endurance athletes and intense body

building relate to protein needs of those trying to follow CR-ON (perhaps with

some milder activity and strength training). In addition, there may be

reasons why these protein needs in endurance athletes were elevated, that didnt

have to do directly with increased protein need for its usual role. Perhaps

they werent eating enough carbohydrates and so used the protein for energy.

>> " The results of nitrogen balance studies on endurance athletes indicates that

these athletes have protein requirements that exceed the USRDA of 0.8

g/kg/day. A study found that endurance athletes (defined as training for at

least 12 hours per week for at least 5 years) require 1.37 g/kg/day of

protein to maintain nitrogen balance compared to 0.73 g/kg/day for sedentary

individuals.

Two published reviews have come to very different conclusions regarding protein

requirements of physically active individuals (Millward J, Bowtell JL, et al.

Physical activity, protein meta-bolism and protein requirements. Proc Nutr Soc

1994;53:223-40. Lemon PW. Do athletes need more dietary protein and amino

acids? Intl J Sport Nutr 1995;5:S39-S61.). Millard estates that there is no

consensus as to whether protein requirements are influenced by physical

activity. Lemon, on the other hand, suggests that protein requirements are

approximately 1.2 to 1.4 g/kg/d for endurance athletes. The Lemon study showed

that the rationale for the additional required protein in endurance and strength

training results from increased protein utilization as an auxiliary fuel during

exercise and to a lesser degree protein deposition during muscle development .

Inadequate intakes of CHO (Lemon PWR, Mullin JP. Effect of initial muscle

glycogen levels on protein catabolism during exercise. J Appl Phys 1980;

48:624-29) and energy (Iyenger A, Narasinga Rao B. Effect of varying energy and

protein intake on nitrogen balance in adults engaged in heavy manual labour. Br

J Nutr 1979;41:19-25.) have also been found to increase protein needs. The

second Lemon study also showed that during prolonged endurance activity,

athletes with low glycogen stores metabolize twice as much protein as those with

adequate stores primarily due to increased gluconeogenesis .

>>>>It appears that weight training can also lead to a daily protein requirement

that exceeds the current USRDA. It has been found that 2.0 to 2.2 g/kg/day

of protein was barely sufficient to maintain nitrogen balance during moderate

intensity weight training. Furthermore, weightlifter's protein

requirements increased proportionally to training intensity. Research has shown

that 2.0 to 2.6 g/kg/day of protein are required for periods of very

intense weight training, whereas protein intakes of 2.0 g/kg/day maintained a

positive nitrogen balance during periods of less intense weight training. "

These increased values for strength athletes may actually reflect requirements

during early stages of resistance training and not an increased longterm need.

(Butterfield G, Kleiner S, Lemon P, et al. Methods of weight gain in athletes

(Roundtable). Sport Sci Exch 1995;6:1-4.).

As i have posted other data that the .8g/kg seems to support postive nitrogen

balance even in those engaged in moderate to heavy exercise.

Jeff