Effect of cysteine-rich whey protein (immunocal®) supplementation in combination with resistance training on muscle strength and lean body mass in non-frail elderly subjects: a randomized, double-blind controlled study.

OBJECTIVES: The purpose of the present study was to examine the effect of a cysteine-rich whey protein (Immunocal®) supplementation in combination with resistance training on muscle strength and lean body mass (LBM) in elderly individuals. We hypothesized that the cysteine-rich whey protein (Immunocal®) group would experience a greater increase in muscle strength and lean body mass versus the control group (casein).

DESIGN: Randomized double-blind controlled intervention study.

SETTING: Institut de Recherches Cliniques de Montréal in Montreal, Canada.

PARTICIPANTS: Ninety-nine non-frail elderly subjects were recruited.

INTERVENTION: Participants were randomly assigned into two groups. The experimental group received a cysteine-rich whey protein isolate (Immunocal®) (20 g/day) and the control group received casein (20 g/day) during a 135-day period. In addition, both groups performed the same resistance training program (3 times per week).

MEASUREMENTS: Body composition (DXA) and muscle strength (leg press) were measured.

RESULTS: Of the 99 recruited participants, 84 completed the 135-day study period. Of these, 67 subjects (33 in the casein group and 34 in the Immunocal® group) complied and used at least 80 % of the study product and completed at least 80 % of their training sessions. Results in this selected group show an increase in all three muscle strength variables (absolute, normalized by BW and by LBM) by 31.0 %, 30.9 % and 30.0 %, respectively in the casein group as well as 39.3 %, 39.9 % and 43.3 %, respectively in the Immunocal® group after the intervention (p < 0.05). The increases in muscle strength favored Immunocal® versus casein by approximately 10 % when expressed in kg per kg BW and in kg per kg LBM (p < 0.05). No significant changes were found between pre-and-post intervention in both groups for total LBM.

CONCLUSIONS: Our findings showed increases in muscle strength in both groups after resistance training, however, significant additional increases were observed in muscle strength with the addition of a cysteine-rich whey protein (Immunocal®) versus casein.