Fitness professionals know that some people excel in exercise programs more easily than others. Skeptical personal trainers raise an eyebrow at clients who claim adherence but improve at a snail’s pace. However, rate of progress could be outside your client’s control. According to a recent study, some individuals may not possess the “exercise gene.” The study was published online ahead of print in the Journal of Applied Physiology (doi:10.1152/japplphysiol.00973.2010).

The researchers analyzed several hundred thousand single nucleotide polymorphisms (SNPs)—also known as DNA sequence variations—from nearly 500 individuals from three separate studies. Each study included a protocol in which the participants exercised at various percentages of VO2max. Each individual’s VO2max was assessed prior to and at the conclusion of each respective protocol.

At study completion, the scientists found that some participants had improved their VO2max, while others had not. They then studied the individuals’ SNPs to determine a possible association with VO2max. The researchers identified “a panel of 21 SNPs, which accounted for 49% of the variance in VO2max trainability.” Also, it was determined that individuals who possessed nine or fewer of the SNPs improved VO2max by 221 milliliters per minute (ml/min). Those with 19 or more of the SNPs improved VO2max by an average of 604 ml/min. “These genomic predictors of the response of VO2max to regular exercise provide new targets for the study of the biology of fitness and its adaptation to regular exercise,” the study authors observed.