Effect of Exercise Intensity on Exercise-Induced Lymphocyte Apoptosis

Abstract

Because lymphocyte apoptosis is significantly elevated immediately following high-intensity exercise in humans, it seems intuitive that the cell death process must be initiated at some point during the task. This study was designed to determine whether exercise-induced lymphocyte apoptosis occurs at a threshold level of intensity, or exists only following maximal or near-maximal exercise intensities. Fourteen untrained subjects completed a discontinuous, incremental treadmill test to exhaustion (.VO(2max)). Blood for films was sampled before the test, immediately after each work stage, and for 1-h postexercise. Blood smears were stained with May-Grünwald Giemsa and lymphocytes were evaluated for characteristic features of apoptosis. The apoptotic index (AI) during exercise at 38 % .VO(2max) was similar to pre-exercise but significantly elevated at an intensity approximating 61 % .VO(2max) (p < 0.0001). Significant increases in apoptosis were noted with additional elevations in exercise intensity (i.e., 76 %, 89 %, and 100 %, p < 0.0001). Following 20 min of recovery, AI was significantly lower than values obtained immediately postexercise (p < 0.0001). Forty minutes of recovery resulted in a further significant decrease (p < 0.0001), and by 1-h postexercise, AI was similar to pre-exercise values. Results indicate that the exercise intensity threshold for inducing an increase in lymphocyte apoptosis occurs between 40 and 60 % .VO(2max). In addition, since values return to baseline within 1 h following exhaustive exercise, it is unlikely that factors responsible for the apoptotic response in lymphocytes maintain a prolonged presence once exercise has been terminated.

Efeito do exercício no sistema imune: resposta, adaptação e sinalização celular

“…Significant increases in the exercise-induced apoptosis indices were observed with a gradual load increase, reaching the maximum peak after an exhaustive exercise (100% VO 2max ), reaching an apoptosis percentage of 22.4 ± 0.4%. After 20 minutes of recovery, the apoptotic index was significantly lower, dropping even more after 40 min, and reaching to the basal levels after 60 min post-exercise 72 . Intense exercise was also able to decrease the glutathione concentration (GSH) of lymphocytes, inducing oxidative stress, while the 8, 9 and 3 active caspases content and the DNA fragmentation appeared to increase 75 .…”

“…Although the concentration of all lymphocyte subpopulations increases, the percentage of TCD4+ cells decreases due to the fact that the NK cells increase more than any other subpopulation 26,59 . The decrease in the lymphocyte concentration in the post exercise period may be, at least partly, a consequence of an apoptosis mechanism 72 . Higher lymphocytes apoptosis percentage in humans has been described immediately after the performance of high-intensity exercises [72][73][74] .…”

“…The decrease in the lymphocyte concentration in the post exercise period may be, at least partly, a consequence of an apoptosis mechanism 72 . Higher lymphocytes apoptosis percentage in humans has been described immediately after the performance of high-intensity exercises [72][73][74] . The level of lymphocytes apoptosis when the exercise was performed at 38% VO 2max (6.9 ± 0.5%) was similar to the basal levels (6.2 ± 0.2%) and significantly increased when the exercise intensity reached 61% VO 2max (10.4 ± 0.6%).…”

“…Intense exercise was also able to decrease the glutathione concentration (GSH) of lymphocytes, inducing oxidative stress, while the 8, 9 and 3 active caspases content and the DNA fragmentation appeared to increase 75 . Some authors tend to associate intense exercise to apoptosis due to the activity of the high levels of catecholamine produced 72 , while others associate it to the increase of oxidative stress 75,76 . Kruger et al 77 showed that the leukocytes redistribution, a crucial mechanism for hematopoiesis regulation, was active during the alteration in the lymphocytes concentration promoted by the exercise.…”

Effects of unaccustomed downhill running on muscle damage, oxidative stress, and leukocyte apoptosis

“…This decline in lymphocyte count may last from several hours up to days and may, at least in part, account for post-exercise immune suppression [5][6]. The majority of studies investigated the effects of exercise on lymphocyte apoptosis and proposed exercise intensity and duration as two determinants of lymphocyte apoptosis [7][8][9][10]. It was reported that high intensity or exhaustive exercise can elicit increases in muscle damage [11][12] and oxidative stress [13][14], which consequently induce leukocyte apoptosis in blood [15][16].…”