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20.10.2012

Pulsed administration strengthens anabolic effect of proteins

Recently we wrote about a study in which convalescing people in their eighties built up more muscle mass when they consumed their daily protein allowance not spread over the day, but three-quarters of it in one go during their midday meal. In 1999 the French nutritionist Marie-Agnès Arnal, of the INRA research institute, published a study financed by Danone in which a protein pulse diet combined with a slightly raised protein intake had an anabolic effect on subjects in their sixties.

Arnal's study was small: 15 women took part. For several weeks before the experiment started [adaptive period] the women consumed a daily 1.2 g protein per kg lean body mass; during the two weeks of the experiment itself they consumed 1.7 g protein/kg lean body mass/day [experimental period]. In terms of kg bodyweight you're talking about a protein intake of 0.74 and 1.05 g protein/day respectively.

Half of the women distributed their protein intake over 3-4 meals per day [spread diet] and the other half consumed 80 percent of their daily protein allowance during lunch [pulse diet].

The women in the spread-diet group lost 0.33 kg lean body mass, as the figure below shows. That was a statistically significant effect. The women in the pulse-diet group gained 0.10 kg lean body mass, but this effect was not statistically significant.

When the researchers measured the amount of nitrogen [N] in the women's urine they discovered that those on the protein pulse diet retained more nitrogen than they had consumed. That would seem to indicate that the women had built up muscle mass.

The researchers calculated the amount of proteins that the subjects built up and broke down, and discovered that the protein pulse diet group built up 19 percent more and broke down 16 percent more than the spread-diet group.

"Insofar as such results will be confirmed in a larger group of subjects, modulation of the pattern of protein feeding with respect to dietary habits (i.e., the pulse diet in this study) may be a more attractive option than simply increasing the protein intake to improve protein turnover and protein retention in elderly women", the researchers conclude.

This study doesn't answer question as to whether this approach can benefit athletes, let alone strength athletes. For strength athletes, who consume two to three times more protein per kg bodyweight than the women in this 1999 study, concentrating protein intake may not be so simple.

Source:
Am J Clin Nutr. 1999 Jun;69(6):1202-8.

More:
Human study: protein pulse gives anabolic stimulus 18.10.2012