Genetic Markers for Bodybuilding
The general strategy adopted by most present-day competitive bodybuilders is to make muscle gains for most of the year (known as the "off-season") and approximately 12–14 weeks from competition attempt to lose body fat also known as the "cutting" phase. If a bodybuilder knew what genes they had it would make this arduous journey to the stage a whole lot easier..
The precise effectiveness of the cutting and bulking strategy is unknown, with only limited observational case studies on the subject. There are three recognised components of body build; type, size and composition. In sport science we use the terms Ectomorph, Endomorph and Mesomorph, in genetics we can precisely identify a person's genotype. One's body tends to deposit fat according to its genetic code (ADRB2 gene). If you have the CC/CG genotype you have a predisposition to having a leaner body mass and when combined with proper strength training and nutrition makes for excellent results.
Someone with the GG genotype is predisposed to increase their fat mass. Although this may sound alarming to most, many top level athletes who have been training for their entire lives posses this genotype. It is good knowledge for a bodybuilder to know as they must make better nutrition choices especially in the bulking season as a bigger caloric surplus and longer bulking phase will create more unwanted fat tissue. A bodybuilder with this genotype may choose not to adopt the conventional strategy, as it often results in significant unwanted fat gain during the "bulking" phase. Alternatively they may attempt to increase muscle mass in a way without any gain in fat using clean bulking.
The cutting phase entails remaining in a net negative energy balance (calorie deficit) along with higher rep training and fasted cardio sessions. The main goal of cutting is to oxidize fat but also to preserve as much muscle as possible. Someone with the GG genotype will certainly have to monitor their caloric intake more rigorously than their CC and CG counterparts as they are predisposed to retaining fat in unwanted areas.
Bodybuilders use three main strategies to maximize muscle hypertrophy; strength training, specialized nutrition, and adequate rest including sleep and recuperation between workouts. Weight training causes micro-tears to the muscles being trained, this is generally known as microtrauma. These micro-tears in the muscle contribute to the soreness felt after exercise, called delayed onset muscle soreness (DOMS). This soreness becomes most apparent a day or two after a workout. Monocarboxylate transporter-1 (MCT-1) is involved in lactate transport and oxidative metabolism.
Levels of MCT-1 increase with exercise in order to remove lactate from the muscles. Higher gene levels mean better removal rates, which means higher intensity exercise and better performance. The more oxidative, slow twitch muscle fibers contain more MCT-1 in contrast to the more glycolytic, fast twith fibers, which contain little or no MCT-1. Slow twitch fibers contain more MCT-1 because that compound is effective at transporting lactate into other tissues that need lactate to produce energy. So more MCT-1 is activated to bring the lactate into fast-twitch muscles, where it's processed to produce energy. A base change in the MCT-1 gene results in a deficiency of the enzyme involved in lactate transport out of the skeletal muscle.
A bodybuilder with the AA genotype has a more effective baseline removal of lactic acid and will be able to train harder for longer. Bodybuilders with either AT/TT genotypes are less effective at removing lactic acid and may find it more difficult to recover from supersets or dropsets.
Weight training aims to build muscle by prompting two different types of hypertrophy: sarcoplasmic hypertrophy and myofibrillar hypertrophy. Sarcoplasmic hypertrophy leads to larger muscles and so is favored by bodybuilders more than myofibrillar hypertrophy which builds athletic strength. Sarcoplasmic hypertrophy is triggered by increasing repetitions, whereas myofibrillar hypertrophy is triggered by lifting heavier weight. In either case, there is an increase in size and strength of the muscles. The ACTN3 gene encodes for a protein called alpha-actinin-3, which is a major structural component of fast twitch muscle fibers.
Many trainees like to cycle between the two methods in order to prevent the body from adapting (maintaining a progressive overload), possibly emphasizing whichever method more suits their goals. A bodybuilder with RR genotype are best conditioned and built for fast twitch power and speed. Training regiments, conditioning and performance strategies should be designed around optimizing this potential. RX genotype athletes are the optimal mix of both predispositions whereas the XX genotype are best conditioned for slow twitch and endurance and will find it difficult to produce adequate hypertrophy gains needed for a bodybuilding competition.