EXPERIMENTAL-MODEL OF SHORT-TIME EXERCISE-INDUCED PRECONDITIONING IN POAD PATIENTS

Regular physical exercise improves walking performance in patients aff ected with peripheral obliterative arterial disease (POAD). The mechan isms underlying the phenomenon are still controversial. In order to ve rify the hypothesis that physical conditioning of lower limbs on a tre admill and ischemic preconditioning of the heart could share some biol ogical aspects, 14 POAD subjects underwent a training program on the t readmill consisting of five repeated submaximal exercises at five-minu te and two-hour intervals preceding the maximal tolerance test. Moreov er, a protocol with two daily submaximal walking exercises over one we ek was also performed. Pain-free and total walking distance were measu red before and after they performed the program. Moreover, plasma leve ls of adenosine and adenosine triphosphate (ATP) were measured and pol ymorphonuclear (PMN) leukocyte activity was studied together with theo logic parameters. Pain-free distance was prolonged by 15.4% and 14.3%, and total distance was prolonged by 23.1% and 26.9%, in the exercises with five-minute and two-hour intervals, respectively. After one week of daily exercises, the onset of pain and the end of the test were de layed by 24% and 43.7%, respectively. An improvement in blood rheology and a reduced PMN reactivity were also observed with the three protoc ols, associated with an increase in plasma levels of adenosine and ATP . Similarly to ischemic preconditioning in the heart, the possibility is suggested that an adenosine-mediated mechanism may contribute to th e development of physical conditioning in treadmill-trained POAD patie nts.