Purine metabolism in sprint- vs endurance-trained athletes aged 20‒90 years

Abstract

Purine metabolism is crucial for efficient ATP resynthesis during exercise. The aim of this study was to assess the effect of lifelong exercise training on blood purine metabolites in ageing humans at rest and after exhausting exercise. Plasma concentrations of hypoxanthine (Hx), xanthine (X), uric acid (UA) and the activity of erythrocyte hypoxanthine-guanine phosphoribosyl transferase (HGPRT) were measured in 55 sprinters (SP, 20‒90 years), 91 endurance runners (ER, 20‒81 years) and 61 untrained participants (UT, 21‒69 years). SP had significantly lower levels of plasma purine metabolites and higher erythrocyte HGPRT activity than ER and UT. In all three groups, plasma purine levels (except UA in UT) significantly increased with age (1.8‒44.0% per decade). HGPRT activity increased in SP and ER (0.5‒1.0%), while it remained unchanged in UT. Hx and X concentrations increased faster with age than UA and HGPRT levels. In summary, plasma purine concentration increases with age, representing the depletion of skeletal muscle adenine nucleotide (AdN) pool. In highly-trained athletes, this disadvantageous effect is compensated by an increase in HGPRT activity, supporting the salvage pathway of the AdN pool restoration. Such a mechanism is absent in untrained individuals. Lifelong exercise, especially speed-power training, limits the age-related purine metabolism deterioration.

Figure 1

Relationships between age and plasma concentrations of purine metabolites at rest and 5 min after exercise until exhaustion in speed-power trained athletes (■, —), endurance-trained athletes (Δ, – – –) and untrained individuals (○,^……). Resting and post-exercise hypoxanthine (panels A and B, respectively) and xanthine (panels C and D, respectively) concentrations significantly increase with age in all groups whereas uric acid (panels E and F, respectively) only increases in athletic groups.

Figure 2

Relationship between age and red blood cell HGPRT activity at rest in speed-power trained athletes (■, —), endurance-trained athletes (Δ, – – –) and untrained individuals (○,^……). A significant increase in HGPRT activity with age is visible in both athletic groups but not in untrained individuals.