Table 2 The effects of physical activity on telomere biology: interventional studies

Laye et al. [107]

8 men and 1 woman, endurance athletes (44 ± 2 years, 7 male)

TL, Telomerase (hTERT, hTERC) and shelterin complex proteins (e.g. TRF2):

PBMC and skeletal muscle

qPCR

Endurance athletes: completed ≥ 1 ultra-marathon of ≥ 60 km

PA: daily marathon distances, total 183 miles over 7 days

TL & telomerase: blood samples and muscle biopsy pre- (2 wks before) and post- (22-24 h after) competition

No significant difference in rTL or telomerase activity with ultra-endurance PA (telomerase activity not detectable in skeletal muscle)

Significant increase in mRNA expression of shelterin complex proteins in PBMCs

Higher TRF2 found in skeletal muscle versus PBMCs

Borghini et al. [47]

62 men and women

n = 20 endurance athletes (45.4 ± 9.2 years)

n = 42 sedentary controls (45.9 ± 9.5 years)

TL: Saliva

qPCR

Endurance athletes: history of 59.4 km/week ultra-trail running for 13.15 years, ages grouped into tertiles

PA: 330 km trail with incline of 24,000 m, duration of < 150 h

TL: samples at baseline (1–2 d before race), intermediate point (148 km), and race completion (< 1 h)

Controls: healthy, inactive, no competitive sports history

↓ Significantly reduced rTL in group of endurance athletes with PA (at intermediate point and at race completion) versus baseline

↑ Significantly longer TL in endurance athlete group (pre-PA) versus controls, largest difference of TL in older (≥ 53 years) group (pre-PA) versus age-matched controls

Diman et al. [131]

10 men, healthy, moderately active

(20 ± 0.6 years)

n = 5 low-intensity group

n = 5 high-intensity group

TERRA: Skeletal muscle

qRT-PCR

PA: 45 min cycling, with target of 50% VO₂ peak (low-intensity) and 75% VO₂ peak (high-intensity) of endurance exercise

TERRA: biopsies before, immediately after, and 2.5 h after PA

↑ Significant increase of TERRA levels immediately after and 2.5 h after PA versus before PA, for in both high- and low-intensity groups

Cluckey et al. [127]

19 men and women, healthy

n = 11 young group (22 ± 2 years)

n = 8 older group (60 ± 2 years)

Telomerase (hTERT and TRF2): PBMC

qRT-PCR

PA: 30 min cycling, varied workloads, with target of 90% VO₂ max (high-intensity)

TL: blood samples pre-PA, and at 30, 60, and 90 min post-PA

↑ Significant increase in relative hTERT levels with high-intensity PA versus pre-PA (greater increase in young group)

Highest post-PA hTERT levels at 60 min for the older group and at 90-min for younger group

↑ Significantly greater increase in hTERT and TRF2 expression in men versus women, independent of age

Gagnon et al. [98]

25 men and women

n = 15 expedition group (23.5 ± 7.4 years)

n = 10 controls (31.1 ± 10.8 years)

TL: Leukocytes

qPCR

PA: 260 km canoeing expedition (6–9 h/d) low to moderate intensity, for 14 days

TL: blood pre- (24 h before) and post- (3 h after) expedition

No significant change in TL between the expedition and control groups

Denham et al. [167]

34 men, healthy

(31 ± 10 years)

TL: sperm

qPCR

Cardiopulmonary exercise test to exhaustion

Intervention: 3 sessions/week of sprint intervals for 6 wks, vigorous intensity; conducted by a subset (n = 10)

TL: sperm donation before the test (n = 34); post PA intervention (n = 10)

No significant correlations between TL, fitness or exercise performance

Positive correlation between TL and improvements in cardiorespiratory fitness after intervention

Brandao et al. [56]

20 women, premenopausal, obese

(20–40 years)

TL: Leukocytes

qPCR

PA: 165 min/week (55 min/session, with 3 sessions/week) for 8 wks

PA intensity: 75–90% HR_max and increasing multiple RM

TL: blood samples pre- and post-PA intervention

↑ Significant increase in rTL with post-PA versus pre-PA

↑ Significant inverse correlation between TL and waist circumference post-PA versus pre-PA

Hernando et al. [123]

149 men and women, healthy, non-smoking (19–67 years)

n = 96 ultra-trail runners

n = 53 sedentary controls

TL: Blood;

SOD2 rs4880: Saliva

qPCR

Endurance athletes: history of ≥ 1 ultra-marathon of ≥ 60 km

PA: 107 km ultra-trail race

TL: blood samples pre- (1 d before) and post- (1–2 d) competition

↑ Significantly longer TL in older/elderly runners (≥ 40 years) versus age-matched controls

Significant association of shorter rTL with SOD2 rs4880 polymorphism

No difference in rTL with previous race training