Branched-chain amino acids (BCAAs) — leucine, isoleucine, and valine — are critical triggers for muscle protein synthesis after training. Your genes affect how efficiently you metabolise BCAAs and use them to build muscle. Some people respond powerfully to BCAA supplementation; others see little benefit. Knowing your BCAA metabolism helps optimise post-workout nutrition. Poor BCAA utilisation can limit muscle growth and increase the risk of muscle breakdown during intense training.

Caffeine doesn't just boost endurance — it also affects strength, power output, and muscle activation during resistance training. Your genes determine how sensitively your muscles respond to caffeine stimulation. High responders can experience significant strength gains from pre-workout caffeine; low responders may feel minimal benefit. Knowing your responsivity helps decide whether caffeine supplementation is a worthwhile training aid or an unnecessary addition to your pre-workout routine.

Creatine is one of the most researched sports supplements for muscle strength and power. However, your MYLK1 gene affects how dramatically your muscles respond to creatine loading. Responders see significant strength and power improvements; non-responders see minimal changes. Knowing your genetic response helps decide whether creatine supplementation is worth investing in. Non-responders who force high-dose creatine intake may experience gastrointestinal discomfort without meaningful performance benefits.

Muscle fibres come in two main types: slow-twitch for endurance and fast-twitch for power and speed. Your genes influence how many fast-twitch fibres you have and how effectively they are recruited during explosive exercise. More fast-twitch activation supports strength, sprinting, and power sports. Knowing your fibre profile helps tailor training. Individuals with lower fast-twitch activation may find power and strength sports more challenging and require more targeted neuromuscular training.

After intense exercise, your muscles undergo a controlled inflammatory process that drives repair and growth. IL-6 is a key signalling molecule in this response. Your genes influence how much IL-6 is released post-exercise and how long inflammation lasts. Optimal IL-6 response supports muscle adaptation; excessive or insufficient response hinders recovery. Knowing your IL-6 profile helps optimise training frequency. High IL-6 variants may need more recovery time between sessions to avoid overtraining.

During intense exercise, your muscles produce lactate. The MCT1 gene controls how efficiently lactate is cleared and recycled as energy. Fast clearance means quicker recovery between hard sets and greater training capacity. Slow clearance causes more fatigue and longer recovery periods. Knowing your MCT1 type helps optimise training intensity and rest periods. Poor lactate clearance limits the volume of high-intensity training you can sustain and may slow overall muscle development.

Leptin is a hormone that regulates hunger, metabolism, and fat storage. Your genes affect leptin sensitivity and how your body composition responds to training. Some people see rapid body composition improvements with exercise; others plateau despite consistent effort. Knowing your leptin-training interaction helps manage expectations and refine training and nutrition approaches. Leptin resistance linked to unfavourable variants can make fat loss more challenging and increase the risk of plateaus.

TNF-alpha is an inflammatory signalling molecule released after intense exercise that drives muscle repair. Your genes affect how much TNF-alpha you produce post-training. The right amount stimulates repair and growth; too much causes excessive damage and prolonged soreness. Knowing your TNF-alpha response helps plan recovery strategies and training frequency. High TNF-alpha variants may experience greater exercise-induced muscle damage, longer soreness, and higher risk of injury with insufficient recovery.

IGF-1 (Insulin-like Growth Factor 1) is one of the most powerful muscle-building hormones in the body, stimulated by training and nutrition. Your genes influence your natural IGF-1 levels and how strongly training triggers its release. Higher IGF-1 response means greater muscle growth potential. Knowing this helps set realistic muscle-building goals. Lower genetic IGF-1 response may limit natural muscle growth rate and require optimised training and nutritional strategies to compensate.

mTOR is a cellular signalling pathway that acts as the master switch for muscle protein synthesis and growth. Your genes influence how responsive your mTOR pathway is to training and protein intake. High mTOR responsiveness means greater muscle-building potential from the same effort. Knowing your mTOR sensitivity helps personalise protein timing and training intensity. Low mTOR responsiveness may limit hypertrophy gains and require higher protein intake and training volume to achieve similar results.

While genetics set a baseline for muscle mass potential, certain gene variants affect how powerfully lifestyle factors like diet, sleep, and exercise translate into muscle development. Some people build and maintain muscle mass easily; others struggle despite consistent effort. Knowing your genetic muscle mass profile helps adjust expectations and fine-tune training and nutrition. Unfavourable variants increase the risk of muscle loss with age and require more deliberate lifestyle strategies to preserve lean mass.

ACTN3 is often called the 'speed gene.' It codes for alpha-actinin-3, a protein found exclusively in fast-twitch muscle fibres. People with the active version tend to have better power, speed, and explosiveness. Those without it are better suited to endurance activities. Knowing your ACTN3 type helps align training with your natural strengths. Absence of functional ACTN3 reduces explosive power output and sprint performance, but may enhance endurance capacity.

ACTN3 is often called the 'speed gene.' It codes for alpha-actinin-3, a protein found exclusively in fast-twitch muscle fibres. People with the active version tend to have better power, speed, and explosiveness. Those without it are better suited to endurance activities. Knowing your ACTN3 type helps align training with your natural strengths. Absence of functional ACTN3 reduces explosive power output and sprint performance, but may enhance endurance capacity.

Beyond raw genetics, certain variants influence how powerfully lifestyle factors convert into muscle strength gains. Some people respond dramatically to resistance training; others see modest strength improvements despite identical programmes. Knowing your strength response profile helps personalise training load, frequency, and progression. Unfavourable variants may require longer adaptation periods and more deliberate strength-focused programming to achieve significant gains and reduce the risk of strength loss with ageing.

Myostatin is a protein that limits muscle growth — essentially a natural brake on how much muscle your body can build. Your genes influence myostatin levels. Lower myostatin activity allows greater muscle hypertrophy; higher activity limits how large muscles can grow. Knowing your myostatin profile helps set realistic muscle-building targets and identify whether specialised training or nutritional strategies could help overcome genetic limitations in muscle development.

Nitric oxide increases blood flow to muscles during exercise, delivering more oxygen and nutrients for performance and growth. Your genes affect how much nitric oxide your muscles produce during training. Better nitric oxide production means stronger 'muscle pumps,' faster nutrient delivery, and enhanced recovery. Knowing this helps determine whether dietary nitrates or pre-workout supplementation would benefit you. Lower nitric oxide production can limit training performance, muscle fullness, and post-workout nutrient delivery.

Recovery rate — how quickly your body repairs muscle damage and restores performance after training — is significantly influenced by genetics. Some people bounce back quickly; others need substantially more time between sessions. Knowing your genetic recovery profile helps avoid overtraining and optimise training frequency. Poor genetic recovery capacity combined with insufficient rest increases the risk of injury, chronic fatigue, hormonal disruption, and long-term performance plateaus.

Your genes influence how effectively your body absorbs, digests, and uses different protein sources — including whey, casein, and plant proteins. Some people respond exceptionally well to protein supplementation for muscle repair and growth; others gain little additional benefit beyond whole food intake. Knowing your protein utilisation profile helps decide whether supplementation is worthwhile and which type is most suitable. Poor protein absorption can limit muscle recovery despite adequate intake.

Different people respond differently to high-rep versus low-rep training due to muscle fibre composition and metabolic genetics. Some individuals build more muscle with higher rep ranges (12-20 reps); others respond better to heavier, lower-rep training (3-6 reps). Knowing your genetic optimal rep range helps design more effective workouts. Training consistently outside your genetically optimal rep range can result in suboptimal hypertrophy, reduced strength gains, and increased risk of training plateaus.

Rep tempo — how fast or slow you perform each repetition — affects muscle activation, time under tension, and growth stimulus. Your muscle genetics influence which tempo produces the strongest growth response for you. Some people benefit from slow, controlled reps; others respond better to explosive movements. Knowing your optimal tempo helps fine-tune training. Using the wrong tempo for your genetic profile can reduce training effectiveness and increase the risk of joint strain.

VEGFA is a gene that promotes the growth of new blood vessels in response to resistance training, improving muscle oxygen and nutrient delivery. Strong VEGFA response means your muscles adapt more efficiently to strength training. Knowing your response level helps optimise training volume and intensity. Reduced VEGFA response may limit vascular adaptations to resistance training, potentially slowing strength and muscle gains and reducing the cardiovascular benefits of regular weight training.

The optimal rest period between sets is influenced by your genetic muscle recovery speed and energy system efficiency. Some people recover ATP (energy) quickly and can train effectively with short rests; others need longer recovery to maintain performance. Knowing your genetic rest requirement helps structure workouts for maximum effectiveness. Training with insufficient rest for your genetic type leads to accumulated fatigue, reduced performance quality, and higher risk of overuse injuries.

Sarcopenia is the age-related loss of muscle mass and strength that begins as early as your 30s. Your genes significantly influence how quickly this process occurs. Some people maintain muscle mass well into later life with minimal effort; others experience rapid decline. Knowing your sarcopenia risk empowers you to start strength training and protein optimisation early. High sarcopenia risk is associated with frailty, falls, metabolic decline, and reduced quality of life in older age.

The optimal number of sets per exercise or muscle group for maximum growth and strength is partially determined by genetics. Some people respond to lower training volume (2-3 sets per exercise); others need higher volume (4-6 sets) for the same stimulus. Knowing your genetic optimal volume prevents both under-training and overtraining. Consistently performing too few or too many sets for your genetic profile can limit progress, increase fatigue, and raise the risk of burnout.

Your basal metabolic rate (BMR) is the number of calories your body burns at rest just to keep you alive. UCP2 is a gene that influences how efficiently your cells convert food into energy versus heat. Some people have naturally high BMRs and burn more calories at rest; others have lower BMRs and store more. Knowing your genetic BMR helps set accurate calorie targets and explains why standard diet advice doesn't work equally for everyone.

APOA5 is a gene that regulates how your body manages triglycerides — fats circulating in the blood. Some variants lead to significantly higher blood fat levels after eating, even on a healthy diet. Elevated triglycerides increase cardiovascular risk and can impair weight management. Knowing your APOA5 type helps personalise dietary fat choices. Unfavourable variants are associated with markedly raised triglyceride levels, increasing risk of pancreatitis and cardiovascular disease.

Your genes determine how well your body metabolises carbohydrates and converts them to fat versus energy. Some people thrive on higher-carb diets and lose weight easily with moderate restriction; others are highly carb-sensitive and store carbohydrates as fat much more readily. Knowing your carbohydrate metabolism type helps design the most effective dietary strategy for weight loss. Carb-sensitive individuals face higher risk of weight gain and blood sugar issues on standard diets.

The FAAH gene regulates the breakdown of endocannabinoids — natural chemicals that create feelings of pleasure from food, similar to the 'munchies' effect. Some variants break these down slowly, causing prolonged feelings of food reward and cravings. This can drive compulsive overeating behaviours even when not physically hungry. Knowing your FAAH type helps understand emotional eating tendencies. Reduced FAAH activity increases risk of binge eating, food addiction, and obesity.