585signature in muscle prior to training. The general approach taken could accelerate
the discovery of genetic biomarkers, suffi ciently discrete for diagnostic purposes,
for a range of physiological and pharmacological phenotypes in humans.
XRPredict (XRGenomics) is multi-gene DNA test that has been scientifi cally
validated for predicting responses to exercise in human trials and is available to
consumers from the company after sending a buccal smear sample. A report inter-
preting the test results is provided. DNA score test result highlight whether a person
is a high, normal or low responder to aerobic exercise. The report might suggest that
if one is a “low” responder to endurance exercise, one should concentrate on resis-
tance training or refocus the training program. This test is more reliable with a
stronger scientifi c basis than other exercise-related DNA test kits available in the
market. However, the value of this test is limited to VO2max response. The test does
not tell, for example, how exercise might affect the individual’s blood pressure over
the long haul, or whether the insulin sensitivity might change, or if the person would
be able to lose weight. The genetic markers related to these health responses to
exercise are quite different from those related to VO12 max. The gene profi le
accounts for at ~23 % of the variation in how people responded to endurance train-
ing, leaving the rest 77 % of response to exercise up to the individual.
Variations in Exercise-Induced Muscle Hypertrophy and Strength
Gains in skeletal muscle mass with resistance training are also highly variable
between individuals from no change to ∼60 % increases in muscle size. There are a
number of factors that might affect the hypertrophic response, including nutritional
support and genetic variation, and a few individual genetic polymorphisms have
been identifi ed that may explain a small degree of variability in the resistance
training- induced hypertrophic or strength gain phenotype. Muscle hypertrophy, like
the response of muscle to endurance training, is regulated by a complex series of
partially redundant signaling molecules, including the mTORC1 complex. Muscle
hypertrophy is limited by the availability of muscle satellite cells or variations in
their ability to proliferate and integrate in vivo that could involve RNA as well as
protein factors. miRNAs may contribute to heterogeneous muscle hypertrophy
because they have been shown to infl uence skeletal muscle satellite cell prolifera-
tion and differentiation. Several highly expressed miRNAs are selectivity regulated
in subjects that represent the lowest 20 % of responders in a longitudinal resistance
training intervention study (Timmons 2011 ).
Personalized Surgery
Surgery has been traditionally more personalized than drug therapy. Decision to use
surgery and choice of procedure are often tailored to individual patients. Surgery
for some conditions, genotype studies may infl uence the decision for surgery.
Personalized Surgery