The purpose of the present study was to determine
whether 12 months of moderate intensity cycling
would increase the expression of IL-2 (CD25+) receptors in
T helper (CD4+) lymphocytes in men and women aged 65–
75 years. Fourteen men and 10 women completed 52 weeks
of moderate intensity cycling (60% VO2peak). Subjects
trained (TR) three times per week for 45 min per session.
Eight age-matched untrained (UT) male and eight UT
female subjects acted as controls. Resting blood samples
were taken from TR and UT subjects every 4 weeks.
Leukocyte concentration was measured using a full blood
count. PHA-stimulated CD4+ lymphocytes were analysed
for changes in the expression of CD25+, by Xow cytometry.
Training signiWcantly increased VO2peak (l min¡1,
ml kg¡1 min¡1) in male (+14.3, +16%) and female (+16.7,
+27.8%) groups. The TR male group showed a signiWcantly
lower percentage of CD4+CD25+ than the male UT in January
but the TR male percentage was signiWcantly higher
than the UT male group during February, March, April,
May, June, September B and December. The female TR
group showed a signiWcantly higher percentage CD4+CD25+
than the female UT only during July. There were also
signiWcant sequential monthly changes in the percentage of
CD4+CD25+ for male and female UT and TR groups.
SigniWcant increases in the percentage of CD4+CD25+ in
the male TR group suggest training-enhanced lymphocyte
mitogenic responsiveness. Moderate intensity long-term
training may increase the recruitment of active memory
CD4+CD25+ in men rather than women.