The Frequency Of Highly Differentiated And Senescent Blood T-cells Following Two Different Endurance Training Programmes

Abstract

The frequency of highly differentiated and senescent T-cells may increase following intensive periods of endurance training, predisposing an individual to a greater risk of infection due to a shrunken naïve T-cell repertoire. Although the frequency of highly differentiated and senescent T-cells in blood has been shown to increase after acute high intensity exercise, the chronic effect of different endurance training programmes on the frequency of highly-differentiated and senescent T-cells in blood is unknown. PURPOSE: To examine the effects of two 6-week endurance training programmes differing in the intensity distribution on the frequency of low and high differentiated and senescent blood T-cells. METHODS: Twelve well trained male cyclists (age 37.5 ± 6.2 yrs) provided a fasted resting blood sample in the morning before and after two 6-week training periods in a cross-over study design, separated by a de-training period. The two training periods differed in the intensity distribution; polarised (POL) (80 ± 4% of time below the lactate threshold (LT) and 20 ± 4% above the lactate turn point) and threshold (THR) (57 ± 10% of time below the LT and 43 ± 10% of time between the LT and the lactate turn point). Isolated blood lymphocytes were labelled with monoclonal antibodies to assess cell surface co-expression of CD57 and CD28 to identify the proportions of low differentiated (CD28+/CD57-), high differentiated (CD28+/CD57+) and senescent (CD28-/CD57+) cells within both CD4+ and CD8+ T-cell subsets using four-colour flow cytometry. Data were analysed using a linear mixed model. RESULTS: 40km time trial mean power improved in both POL (8.1 ± 7.7%, P<0.001) and THR (4.2 ± 5.7% P<0.05) with no difference in the percentage improvement between the training periods. No changes in the proportion of low or high differentiated or senescent T-cells were found within the CD8+ or CD4+ T-cell subsets. CONCLUSIONS: Following two different 6-week endurance training programmes, there was no effect on the frequency of low or high differentiated or senescent CD8+ or CD4+ T-cells in blood in well trained male cyclists. Therefore, both training protocols provided a sufficient stimulus to improve cycling performance without leaving the athlete at a potentially greater risk of infection due to a shrunken naïve T-cell repertoire.