This is Why You’re Not Building Muscle (6 Scientific Reasons)

DeLauer highlights a study from the Journal of Strength and Conditioning where two groups followed identical resistance programs, but one group added 30 minutes of static stretching twice weekly. The stretching group saw a 31% increase in leg press strength vs 9% in the control, and similar outsized gains in leg extension and hamstring curls. The mechanism is stretch-mediated hypertrophy, where prolonged tension on muscle fibers triggers anabolic signaling. He stresses that this is 'low-hanging fruit' for anyone in the early stages of training who has hit a plateau, as it requires no extra joint stress or loading.

DeLauer cites a European Journal of Sports Science study comparing full ROM, initial stretch partials, and terminal contraction partials. The stretch partials produced superior muscle cross-sectional area increases. He applies this by recommending that after you can no longer complete full reps, you add a few small partials in the beginning of the concentric—e.g., the bottom quarter of a bicep curl or the first part of a leg extension. This technique targets the muscle fibers in their lengthened state, which recent research shows is especially potent for hypertrophy, and serves as a 'plateau buster' that can unlock new growth without overloading the system.

DeLauer explains that aging increases the leucine threshold required to activate mTOR and myofibrillar growth, yet many older adults inadvertently reduce protein intake. He references a conversation with researcher Dr. Mike Ormsby, who demonstrated that a pre-sleep protein shake did not disrupt sleep stages or reduce overnight fat burning, and in fact increased muscle protein synthesis and recovery. DeLauer frames this as a simple, purely supplemental strategy to bridge the gap and ensure the body has enough leucine overnight to support repair.

DeLauer argues that inflammation often originates in the gut, as increased permeability allows bacterial lipopolysaccharides to enter the bloodstream, triggering an immune response that upregulates NF-kB and muscle protein degradation. Healing the gut mucosal layer with collagen, gelatin, and bone broth, while avoiding dietary emulsifiers (especially polysorbates), reduces that inflammatory load. He also emphasizes that the gut repairs itself during periods of non-eating, so having defined gaps between meals supports the migrating motor complex and gut barrier integrity.

Thomas DeLauer describes a study where two groups of novice lifters followed the same resistance program, but one group added 30 minutes of static stretching twice a week. The stretching group saw a 31% increase in leg press strength, a 27% increase in leg extension, and superior hypertrophy compared to the non-stretching group's 9%, 14%, and 12% respectively. He emphasizes that this effect is most pronounced during the newbie phase, because stretch-mediated hypertrophy pathways are highly responsive when the muscles aren't conditioned to stretch. He frames this as 'low-hanging fruit' — a simple, non-stressful addition that can reboot progress after the initial easy gains end.

DeLauer references a large meta-analysis showing that protein intake was the single largest predictor of hypertrophy. He then dives into two nuances: leucine content and the DIAAS (Digestible Indispensable Amino Acid Score). The DIAAS score measures actual ileal absorbability, i.e., how much of the ingested protein is absorbed in the small intestine. He instructs viewers to search for 'proteins with the highest DIAAS score' to find the most efficient muscle-building proteins. He lists whey protein, milk protein (whey + casein blend), beef, and eggs as the top performers. This approach gives a scientific method to choose protein sources, rather than relying solely on quantity.

DeLauer discusses research from the European Journal of Sports Science comparing full range of motion, initial partials (stretched), and terminal partials (contracted). The initial stretch range of motion elicited the greatest muscle cross-sectional area increases. He applies this by recommending that after a set taken to failure (or one rep in reserve), you pump out a few extra small partials in the stretched position — the bottom of a bicep curl or the beginning of a leg extension. This taps into the stretch-mediated hypertrophy pathway without significantly increasing systemic fatigue or session volume. He personally vouches for it as a 'tremendous' plateau breaker.

DeLauer explains that as we age, we need more leucine to activate mTOR and build muscle, but older adults often consume less protein. He cites Dr. Mike Ormsby, a protein timing researcher he hosted on his channel, who demonstrated that a pre-sleep protein shake did not reduce sleep quality or fat oxidation, and instead improved recovery and muscle protein synthesis. DeLauer recommends a simple mix of protein powder and water (no milk, no carbs) before bed purely as a supplement—not a meal—to hit that heightened leucine threshold.

DeLauer explains that as we age, cellular debris and oxidative stress activate NF-kB, driving muscle protein degradation. However, he argues that a primary source of systemic inflammation is the gut. Disruption of the gut barrier allows lipopolysaccharides from Gram-negative bacteria to enter the bloodstream, activating the immune system and creating a catabolic environment. To heal the gut, he recommends bone broth, collagen protein, and gelatin to support the mucosal layer, avoiding emulsifiers like polysorbate-60/80 (opting for soy or sunflower lecithin instead), and incorporating polyphenols as prebiotics. He also stresses the importance of clear gaps between meals to allow gut repair through the migrating motor complex.