Define? Not genetically based? Size estimators?
Let us consult scripture.
The Quantum Dictionary of Modern Bodybuilding states:
Genetic Potential: [juh-net-ik puh-ten-shuhl] -
noun. 1. The maximum degree of total body hypertrophy an individual bodybuilder can express under optimal training, nutrition, and recovery conditions at a specific age and sex.
Optimal Training Conditions: [op-tuh-muhl trey-ning kuhn-dish-uhns]
-noun 1. The combination of recovery, nutrition, and exercise practices, hitherto known or unknown, that result in the maximal daily hypertrophic rate an individual can present.
The
Theory of Genetic Potential states that an individual's maximal hypertrophy is ultimately constrained by a host of biological factors that are primarily inherited and thus largely immutable (see References). Many bodybuilders rebel against the concept due to a fear that their ideal physique, typically modeled after an IFBB Pro or comic book character, cannot be obtained. It is also used as a cop-out by the frustrated as to why size and/or strength gains are not forthcoming. Critics of Genetic Potential Theory point out that each person's hypertrophic best cannot be predetermined because each person's body is inherently unique. Anthropometric and statistical analysis has resulted in equations estimating maximal limb and torso girth based on quantifiable relationships derived from pre-steroid era bodybuilders (see below).
On Body Size Estimators:
Article describing the scientific basis of body size estimators.
Body Size Estimator # 1
Body Size Estimator #2
Selected References
<div></div><div id="QUOTEHEAD">QUOTE</div><div id="QUOTE">Angiotensin-converting enzyme genotype affects the response of human skeletal muscle to functional overload.
Folland J, Leach B, Little T, Hawker K, Myerson S, Montgomery H, Jones D.
Chelsea School Research Centre, University of Brighton, School of Sport and Exercise Sciences, University of Birmingham and Centre for Cardiovascular Genetics, University College London, UK.
j.folland@bton.ac.uk
The response to strength training varies widely between individuals and is considerably influenced by genetic variables, which until now, have remained unidentified. The deletion (D), rather than the insertion (I), variant of the human angiotensin-converting enzyme (ACE) genotype is an important factor in the hypertrophic response of cardiac muscle to exercise and could also be involved in skeletal muscle hypertrophy - an important factor in the response to functional overload. Subjects were 33 healthy male volunteers with no experience of strength training. We examined the effect of ACE genotype upon changes in strength of quadriceps muscles in response to 9 weeks of specific strength training (isometric or dynamic). There was a significant interaction between ACE genotype and isometric training with greater strength gains shown by subjects with the D allele (mean +/- S.E.M.: II, 9.0+/-1.7 %; ID, 17.6 +/-2.2 %; DD, 14.9+/-1.3 %, ANOVA, P 0.05). A consistent genotype and training interaction (ID DD II) was observed across all of the strength measures, and both types of training. ACE genotype is the first genetic factor to be identified in the response of skeletal muscle to strength training. The association of the ACE I/D polymorphism with the responses of cardiac and skeletal muscle to functional overload indicates that they may share a common mechanism. These findings suggest a novel mechanism, involving the renin-angiotensin system, in the response of skeletal muscle to functional overload and may have implications for the management of conditions such as muscle wasting disorders, prolonged bed rest, ageing and rehabilitation, where muscle weakness may limit function.</div>
<div></div><div id="QUOTEHEAD">QUOTE</div><div id="QUOTE">Variability in muscle size and strength gain after unilateral resistance training.
Hubal MJ, Gordish-Dressman H, Thompson PD, Price TB, Hoffman EP, Angelopoulos TJ, Gordon PM, Moyna NM, Pescatello LS, Visich PS, Zoeller RF, Seip RL, Clarkson PM.
Department of Exercise Science, Totman Building, University of Massachusetts, Amherst, MA 01003, USA.
PURPOSE: This study assessed variability in muscle size and strength changes in a large cohort of men and women after a unilateral resistance training program in the elbow flexors. A secondary purpose was to assess sex differences in size and strength changes after training. METHODS: Five hundred eighty-five subjects (342 women, 243 men) were tested at one of eight study centers. Isometric (MVC) and dynamic strength (one-repetition maximum (1RM)) of the elbow flexor muscles of each arm and magnetic resonance imaging (MRI) of the biceps brachii (to determine cross-sectional area (CSA)) were assessed before and after 12 wk of progressive dynamic resistance training of the nondominant arm. RESULTS: Size changes ranged from -2 to +59% (-0.4 to +13.6 cm), 1RM strength gains ranged from 0 to +250% (0 to +10.2 kg), and MVC changes ranged from -32 to +149% (-15.9 to +52.6 kg). Coefficients of variation were 0.48 and 0.51 for changes in CSA (P = 0.44), 1.07 and 0.89 for changes in MVC (P < 0.01), and 0.55 and 0.59 for changes in CSA (P < 0.01) in men and women, respectively. Men experienced 2.5% greater gains for CSA (P < 0.01) compared with women. Despite greater absolute gains in men, relative increases in strength measures were greater in women versus men (P < 0.05).
CONCLUSION: Men and women exhibit wide ranges of response to resistance training, with some subjects showing little to no gain, and others showing profound changes, increasing size by over 10 cm and doubling their strength. Men had only a slight advantage in relative size gains compared with women, whereas women outpaced men considerably in relative gains in strength.</div>
More References:
ACTN3 genotype is associated with increases in muscle strength in response to resistance training in women.
ACTN3 (R577X) genotype is associated with fiber type distribution.
ACTN3 and MLCK genotype associations with exertional muscle damage.
Circulating angiotensin converting enzyme activity is correlated with muscle strength.
Muscle strength response to strength training is influenced by insulin-like growth factor 1 genotype in older adults.
IGF-II gene region polymorphisms related to exertional muscle damage.
Influence of promoter region variants of insulin-like growth factor pathway genes on the strength-training response of muscle phenotypes in older adults.
