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Endurance and resistance training: effects on telomeres and telomerase

by A. Manolova | 17 September 2019

telomere, telomerase activity, length, ageing, senescence, biology, sport, physical activity, cardiovascular disease, HIIT, endurance, training, resistance

Telomeres and their role in cellular aging, and thus the organism aging (senescence), was brought to light by the Russian biologist Aleksei Olovnikov in 1971. Olovnikov pointed out that the limit of cell replication correlated with telomeres length. Telomeres are located at the end of our chromosomes, their role is literally to protect our DNA during cell replication, to prevent loss of information or any other anomalies. Thus, the telomere can be considered as a shield that avoids poor cell replication by protecting our chromosomes. However, the telomere is shortened with each cell division, and when it reaches a critical size, the cell reaches its replicative limit and the organism ages. Their original length is genetic and therefore different for each individual.

However, in 1985, Elizabeth Blackburn and Carol Greider highlight telomerase, an enzyme capable of limiting telomere shortening by synthesizing new strands of telomeric DNA. Their work was rewarded in 2009 by the Nobel Prize in Physiology or Medicine. Blackburn's work also shows that telomerase not only limits the shortening of telomeres, but also allows them to be lengthened, thereby increasing the replication potential of a cell and thus delaying aging. In addition, following numerous studies (both physiological and psychological), Blackburn and Epel show that telomerase activity and telomere length vary greatly according to many factors: physical activity, dietary habits and psychological stress (learn more about their work with their book: "The telomere effect").

Beneficial effects of physical activity on cellular regeneration and senescence have already been observed. Long-term endurance training is associated with higher telomerase activity and reduced telomeric attrition in young and middle-aged endurance athletes compared to inactive individuals. This phenomenon is also observed in twins where one is active and the other inactive. In the context of cardiovascular diseases, vascular aging is now known to be associated with endothelial dysfunction and atherogenesis. Yet, the specific impact of different types of physical activity is not known. Is there a difference between moderate intensity continuous endurance training (MICT), high-intensity interval training (HIIT) and resistance training (RT)?

The Study

To answer this question, German researchers have studied the impact of different training protocols in sedentary people for 6 months (26 weeks). Their goal was to measure the impact of these protocols on telomerase activity and on telomere length of certain blood cells (leukocytes). For this, the researchers recruited 266 volunteers but only 124 of them completed the experimental protocol. These individuals were divided into 4 groups : a control group (n = 35), a MICT group (n = 26), a HIIT group (n = 29) and a resistance training group (RT) (n = 34). The training protocol consisted of 3 weekly sessions of 45 minutes. People in the control group continued to go about their usual business.

  • For the MICT group, one session consisted of walking/running at 60% heart rate reserve (HRR) (Karvonen formula).
  • For the HIIT group, one session consisted of 10 minutes warm-up to 60-75% HRR and 4 x 4-minute intervals at 80-90% HRR spaced by 3-minute rest intervals at 65-70% HRR and ended with a 10-minute cool-down running at 60-70% HRR.
  • For the RT group, a session consisted of 8 exercises on machine organized in circuit. Participants completed 16-20 repetitions of 20RM on one exercise before moving on to the next, and completed 2 sets in total. The exercises performed were : back extension, crunch, pull-down, seated row, seated leg curl, seated leg extension, seated chest press and lying leg press. The 20RM was reevaluated every 6 weeks and training loads were adjusted.

In addition to this prospective study, the researchers also measured the acute effects of endurance training (MICT) to those of a resistance training (RT) on telomerase activity in leukocytes on a subpopulation of the sample (n = 15) in cross-over manner (that is, all subjects performed both training protocols).

Results & Analyzes

The main results of this study show that 6 months of endurance training, whether MICT or HIIT, can induce an increase in telomerase activity in peripheral blood mononuclear cells (lymphocytes and monocytes) (by 2 to 3-fold) accompanied by an increase in telomere length of leukocytes (lymphocytes and granulocytes). But no improvement was observed for people who participated in the RT group. In the same way, a single session of endurance significantly improves the telomerase activity (immediately after and up to 24 hours) while no improvement was observed after a RT session.

The 3 exercise groups led to a similar improvement in VO2MAX and significantly greater than that in the control group (2.7 ± 3.7 for MICT, 2.8 ± 5.1 for HIIT and 3.0 ± 5.9 for RT, in mL/min/kg). And the researchers found no statistical correlation between the improvement of VO2MAX and the change in telomere length. Still, individuals with above average VO2MAX enhancement demonstrated greater telomerase activity compared to those who responded poorly to exercise. In addition, the researchers observed positive regulation of RNA expression of the inducible isoform of nitric oxide synthase (iNOS) only in the two endurance groups. The mean and maximum heart rates observed during MICT and HIIT training were higher than those seen in RT. The authors assume that this may mean that endurance training induces higher vascular shear stresses which could potentially contribute to the observed cellular effects (via nitric oxide (NO), in particular). It has been shown that the activities of nitric oxide synthase (the enzyme catalyzing the production of nitric oxide in the bloodstream) and telomerase are linked in a signaling pathway regulating exercise-induced vascular protection.

Practical Applications

This study is the first to conduct a randomized, controlled comparison evaluating the effects of different training protocols on telomerase activity and telomere length. The results of this study show that only endurance activities can improve telomerase activity and length of leukocyte telomeres on an acute and chronic basis (26 weeks), confirming the interest of practicing these activities for the prevention of cardiovascular diseases. However, it will be interesting to analyze other types of resistance training more representative of actual workouts with higher intensities and their impact on the activity of telomerase and telomeres, especially in muscular cells.


  1. Werner CM, Hecksteden A, Morsch A, Zundler J, Wegmann M, Kratzsch J, Thiery J, Hohl M, Bittenbring JT, Neumann F, Böhm M, Meyer T and Laufs U. Differential effects of endurance, interval, and resistance training on telomerase activity and telomere length in a randomized, controlled study. Eur Heart J 40 : 34-46, 2019.

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