(PTFS02-03-26) Pea vs Whey Protein Isolate on Body Composition And Muscle Strength In Young Untrained Adults During Resistance Training: Preliminary Analysis of a Double-Blinded RCT

Objectives: Pea protein isolate is often appreciated as a sustainable alternative to whey protein isolate supplement for muscle hypertrophy. The purpose of this study was to compare changes in body composition and muscle strength in healthy untrained adults supplemented with either a pea or whey protein isolate following an 8-week resistance training program.

Methods: Thirty-three healthy, untrained adults 18-30y with a BMI between 18.5 and 28 kg/m² were randomized to supplement 48g of either pea or whey protein isolate during an 8-week progressive resistance training regimen. Subjects and researchers were blinded to the protein supplement and were exercised under instruction twice weekly approximately 1hr/session. Body composition was measured using DXA and strength was measured using several indicators: isometric maximum quadricep strength (IMQS), isometric handgrip strength (handgrip dynamometer), 1-repitition maximum (1RM) chest press, and 1RM leg press. Outcomes were analyzed using linear mixed-effects models (statistical significance: p< 0.05).

Results: Subjects who completed the study protocol (n=26) were predominantly female (69%) and plurality were non-Hispanic white (34.6%). There were no significant differences in body composition changes between treatments. However, within Treatment A, percent lean mass (%LM) increased significantly over the study period (mean change: +0.87 ± 0.36%; p = 0.024), accompanied by a significant reduction in percent body fat (%BF) (−0.96 ± 0.38%; p = 0.018). Similarly, subjects within Treatment B had increased %LM (+0.82 ± 0.31%; p = 0.013) and decreased %BF (−0.83 ± 0.32%; p = 0.018). A significant interaction was observed for leg press 1RM (p = 0.038) favoring Treatment A. Within Treatment A, significant increases were observed in IMQS (+79.9 ± 27.5 Nm; p = 0.010), leg press-1RM (+87.0 ± 21.5 kg; p = 0.001), and chest press 1RM (+6.6 ± 3.1 kg; p = 0.043). Within Treatment B, a significant increase was observed only for chest press 1RM (+6.9 ± 2.6 kg; p = 0.014), whereas increases in IMQS and leg press 1RM did not reach statistical significance.

Conclusions: Both protein sources combined with progressive resistance exercise resulted in significant improvements in body composition and muscle strength over the 8-week intervention.

Funding Sources: Ingredion Inc.