Hormonal
While IL15RA genetic variation (PstI polymorphism) is associated with greater muscle hypertrophy, it is also associated with reduced muscle quality (strength relative to muscle size) gains.
If you have genetic variants associated with high hypertrophy but low muscle quality, you may gain size without a proportional increase in strength. To counter this, prioritize strength-focused training (lower reps, higher load) alongside hypertrophy work to ensure neuromuscular adaptations keep pace with muscle growth.
Arm and leg muscle quality changes... were significantly reduced with the addition of each A allele (P < 0.05)... The PstI AA group demonstrated the greatest hypertrophic response to RET yet the lowest increase in strength.
Why this rating
Consistent findings across multiple muscle groups (arm and leg) in a controlled trial.
Source
Association of interleukin-15 protein and interleukin-15 receptor genetic variation with resistance exercise training responses
Steven E. Riechman et al. · Journal of Applied Physiology · 2004
DOI 10.1152/japplphysiol.00491.2004
More from this paper
- Genetic variation in the IL15RA gene (specifically the PstI polymorphism in exon 7) is strongly associated with greater muscle hypertrophy (lean mass gain) in response to resistance exercise training, although it is associated with reduced muscle quality gains.Good
- Plasma IL-15 protein levels increase acutely after resistance exercise but do not change chronically with training and are not associated with variability in muscle responses.Good
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