Modification induced by a single bout of training exercise on cutaneous microcirculation of patients with PAD.

Modification induced by a single bout of training exercise on cutaneous microcirculation of patients with PAD De Marchi S., Saracino L., Rigoni A., Prior M., Arosio E. Division of Angiology, Department of Medicine, University of Verona. Background: training has a pivotal role in therapy of peripheral arterial disease with claudication, contrasting data are available about prescription of strength exercise in this setting. Some authors suggest a benefit from some low grade strength exercises inserted in training program, other authors exclude anaerobic type of exercise prescription. Cutaneous circulation seems to be an interesting witness of heamodynamic modification acting in lower limb also during muscles activation 1,2,3,4 so we proposed a test consisting in a series of elevations on the forefoot repeated in a rapid sequence, standing with similar work amount compared to a sub-maximal exercise on treadmill as used in training protocol. Aim: to evaluate the effects on cutaneous microcirculation, of a single bout of moderate strength exercise in PAD patients compared with aerobic treadmill exercise and controlled with healthy subjects. Methods: we enrolled 14 patients, with PAD at Fontaine stage II (pain free walking distance 130±45 m - ABI 0,75±11 ), aged 73±4 y, no diabetic/neuropathic patients were allowed; all subjects had a superficial artery occlusion in the symptomatic leg with concomitant 1 or 2 tibial vessels occlusion. They underwent a series of up-standing on forefoot (FUP), successively they performed treadmill exercise (3,2Km/h, 0% slope) to 70% of maximal walking distance; the two exercise were comparable for energy consumption calculated (on treadmill= 0.50 x km x kg of body weight , on heel elevation = kg of body weight x m heel elevation x n° of elevation - respectively 61±22 kcal and 55±11 kcal , p=0,73); 10 healthy matched subjects performed FUP treadmill based on the same energy expenditure . We analyzed microcirculatory flux by means of Laser Doppler flowmetry with probe placed on forefoot of symptomatic leg in patients and on left leg in healthy volunteer; measurements were done at rest and after 1 minute after tests end and with a 2 minutes monitoring. Data were analyzed with Student’s t test for paired data. Results: FUP caused a significant increase in microcirculatory flux in the recovery period in PAD patients (*p<0,05 vs rest - figure) while it caused no significant changes in healthy; treadmill caused a slight decrease in flux at PAD patients’ forefoot, while it caused an increase in healthy (*p<0,05 vs rest- figure). Conclusions: Our study has demonstrated that strength exercise in PAD patients with claudication causes an increase of cutaneous flux , while no significant changes in healthy. Treadmill causes a decrease (not significant) in the period of monitoring as reported in literature in PAD subjects. In healthy volunteers an increased flux after treadmill may be caused by hyperemia in the leg, elicited by exercise with a preserved inflow and a correct distribution in tissues 4,5 ; a component of thermoregulatory vasodilation may be evoked. FUP in controls did not produce a relevant phenomenon perhaps for sympathetic tone prevalence and a reduced overall hyperemia. In PAD patients the increase after FUP may be due to a more pronounced ischemia and a more enhanced and concentrated vasodilation in a distal segment with sympathetic blunting and a more pronounced post exercise hyperemia due to a compensatory vasodilation , involving also cutaneous district. This data may enforce the proposal for dedicated moderate-strength exercises for distal muscles groups in PAD patients. References: 1. Joyner MJ, Casey DP. Muscle blood flow, hypoxia, and hypoperfusion. J Appl Physiol 116: 852–857, 2014. 2. Rossi M, Cupisti A, Perrone L, Mariani S, Santoro G. Acute effect of exercise-induced leg ischemia on cutaneous vasoreactivity in patients with stage II peripheral artery disease. Microvasc Res 2002 Jul;64(1):14-20. 3. Casey DP, Joyner MJ . Local control of skeletal muscle blood flow during exercise: influence of available oxygen . Appl Physiol 111: 1527–1538, 2011. 4. Joyner MJ, Casey DP. Regulation of increased blood flow(hyperemia) to muscles during exercise: a hierarchy of competing physiological needs. Physiol Rev 95: 549–601, 2015. 5. Joshi D. , Shiwalkar A., Cross MR, Sharma SK, Vachhani A., Dutt C. Continuous, non-invasive measurement of the haemodynamic response to submaximal exercise in patients with diabetes mellitus: evidence of impaired cardiac reserve and peripheral vascular response. Heart 2010;96:36–41.