Extreme exercise and oxidative DNA modification

Abstract

Extreme exercise increases oxygen uptake with a potential for increased formation of reactive oxygen species. Damage to biomolecules may occur if such an increase exceeds the protective capacity of antioxidant defence mechanisms. Vigorous exercise amounting to approximately 10 h a day for 30 days increased the rate of oxidative DNA modification by 33% (95% confidence limits, 3-67%; P < 0.02) in 20 men owing to the urinary excretion of 8-oxo-7,8-dihydro-2'-deoxyguanosine, an oxidatively modified deoxynucleoside originating from nuclear DNA repair, oxidation of the nucleotide pool from mitochondrial DNA and/or from cell turnover. Oxidative stress to DNA points to a risk for the development of cancer and premature ageing from extreme exercise.

Effects of Long-Term Aerobic Exercise on the Antioxidant System and Lymphocyte Dna Damage by Triathlon Distance

“…However, such measurement method cannot accurately measure DNA sensitivity. 14 Recently, single-cell gel electrophoresis (SCGE) was used to measure oxidative stress-induced lymphocyte DNA damage. Ostling and Johanson (1984) introduced the microgel electrophoresis method to directly identify the degree of DNA damage in each cell, 15 and it was upgraded by Singh et al to detect DNA damage with greater sensitivity.…”

The effects of intensive, long-term treadmill running on reproductive hormones, hypothalamus–pituitary–testis axis, and semen quality: a randomized controlled study

“…This increase in O 2 utilization may result in the production of ROS at the rates that exceed the body's capacity to detoxify them (Alessio 1993). However, some studies have failed to observe exercise-induced oxidative stress (Poulsen et al 1996, Oztasan et al 2004). An increase in the formation of ROS decreases fertility, as the ROS will attack the membranes of the spermatozoa, decreasing their viability (Irvine 1996).…”

Vitamin E isoform-specific inhibition of the exercise-induced heat shock protein 72 expression in humans

“…However, the rate increases significantly in response to exercise, with the contracting skeletal muscle being a major source of both reactive oxygen species (ROS) (16,30) and reactive nitrogen species (RNS) (5). Although the tissue hosts a number of enzymes (e.g., superoxide dismutase and catalase) and small molecule antioxidants (e.g., vitamins C and E) protecting partly against oxidative stress, augmented oxidative damage to lipids (2), proteins (59), and DNA (57) has been observed after acute physical exercise. Therefore, a second line defense of the cellular integrity consisting of heat shock proteins (HSPs) is present in all living organisms: HSPs are, when located intracellularly, chaperone-like proteins involved in folding of newly synthesized proteins, binding to denatured proteins, and translocation of proteins between subcellular compartments (22).…”