The purpose of this study was to examine the relationship between exercise energy expenditure (EEE) and telomere length, telomerase activity, and hTERT genotype. Sixty-nine male (n = 34) and female (n = 35) participants 50-70 yr. were assessed for weekly EEE level using the Yale Physical Activity Survey. Subjects were grouped according to EEE. Telomere length and telomerase activity were measured in peripheral blood mononuclear cells (PBMCs). Relative telomere length was significantly higher in the Middle EEE group compared to both the low and high EEE groups (p<0.05). Telomerase activity was not different among the three EEE groups. The TT hTERT genotype had significantly greater telomerase enzyme activity than both the CT and CC genotypes (P = 0.013). In conclusion, moderate exercise energy expenditure levels may provide a protective effect on PBMC telomere length compared to both low and high EEE levels. hTERT genotype was associated with telomerase activity.