Effects of the Type and Volume of Physical Activity on Leukocyte Telomere Length in Middle-Aged Men

PURPOSE Leukocyte telomere length (LTL) is a potential indicator of cellular senescence. However, its relationship with the type and volume of regular exercise is unclear. Therefore, we investigated the effects of the type and volume of long-term regular exercise on the LTL in middle-aged men (N=109, mean age=44.7±4.1 years [range: 40-56 years]). METHODS For all participants, the volume of physical activity (PA) was evaluated using a self-report questionnaire, and blood samples were collected simultaneously. We cross-sectionally examined the associations among the type and volume of PA, LTL, telomerase activity (TA), mitochondrial DNA copy number (mtDNA), and body composition in three groups: 1) bodybuilders (BBs) with at least 5 years of athletic experience (n=36, mean age: 42.3±3.3 years [40-51 years]), 2) cyclists (CCs) with an athletic career similar to that of the BBs (n=37, mean age: 45.4±4.4 years [range: 40-53 years]), and 3) healthy ordinary people (CON; n=36, mean age: 46.3±3.3 years [range: 40-56 years]). RESULTS The LTL showed a significant positive correlation with the volume of PA (r=.285, p=.003), regardless of the type of PA. Furthermore, the LTLs were longer in the BB (p=.007) and CC (p=.003) groups (who performed moderate-to-vigorous PA for 150 minutes or more per week) than in the CON group. Conversely, the TA was significantly higher in the BB group (p=.009) than in the CON group; however, it only tended to be high in the CC group (p=.115). There were no intergroup differences in both the mtDNA (p=.127) and 8-hydroxydeoxyguanosine (p=.289) levels. CONCLUSIONS The TA was found to increase, and thus prevent telomere loss, in middle-aged men who performed PA of moderateto-vigorous intensity, regardless of the PA type.