ACTN3 is a protein expressed in fast twitch muscle fibers, which are a type of muscle fiber that contract quickly and with greater force, but are more prone to fatigue. Accordingly, individuals with the genetic variant for fast twitch muscle fibers are more commonly found among the ranks of elite athletes. Interestingly, another line of research has suggested that individuals lacking the fast twtich genetic variant may have had an evolutionary advantage in endurance athleticism and resistance to fatigue. Evidence suggests that folks lacking the fast twitch muscle variant benefit more from long, moderate intensity aerobic exercise, while people with fast twitch muscle fibers have muscles best suited to fast paced interval training.
Circadian rhythms effect immunity, cognitive function, athletic performance, and metabolism. Importantly, many modern life demands lead to circadian misalignment, which can be associated with dire health consequences. Your circadian rhythm is determined by a complex dynamic of demographic, georgraphic, behavioral, and genetic factors. A common mutation in the PER1 gene is associated with either advanced, intermittant, or delayed timing of your circadian rhythm relative to the population. Synchronizing your work, sleep, exercise, and dietary pattern to your circadian rhythm may lead to better overall health.
Though exercise may be the single greatest activity for preventing disease, improving cogntive function, and increasing lifespan, National Health statistics indicate 25% of Americans engage in zero physical activity. The subjective feeling of exercise has been hypothesized to be a determinant of exercise behavior, and the speed of tangible bodily improvements from exercise mat effect motivation in a feedback dependent manner. A mutation in the CREB1 gene has been associated with both temperatue increase to exercise, as well Heart Rate related imporvements in physical fitness as a result of exercise. Folks with this mutation should ensure proper, breathable athletic wear during exercise to prevent overheating, and may benefit from water sports and cold weather exercise. Additionally, they should be more patient in seeing improvements in fitness, which will surely come, though perhaps take longer to see.