Physiological predictors of maximum treadmill walking performance in patients with intermittent claudication.

The purpose of this investigation was to identify physiological predictors of maximum treadmill walking performance (MWD) in patients with intermittent claudication. Forty-five claudicants performed a graded treadmill test to determine MWD, peak oxygen uptake, and gas exchange threshold. Calf muscle oxygenation (StO (2)) at 1 min and time to minimum StO (2) were also measured using near-infrared spectroscopy. On other occasions, peak calf blood flow, resting ankle-brachial index, and pulmonary oxygen uptake kinetics during steady-state walking were assessed. A forward stepwise multiple regression analysis was performed to determine predictors of MWD. A regression model comprising time to minimum StO (2), peak oxygen uptake, and StO (2) at 1 min explained 64% of the variation in MWD. The results suggest that cardiopulmonary fitness and the ability to match oxygen delivery to metabolic demand are important determinants of walking performance in claudicants, and that certain near-infrared spectroscopy variables might be useful in studies that evaluate the mechanisms of clinical improvement with different treatment interventions.

Nordic poles immediately improve walking distance in patients with intermittent claudication.

OBJECTIVES: To investigate the immediate effects of Nordic pole walking (NPW) on walking distance and cardiopulmonary workload in patients with intermittent claudication. METHODS: Using a standardised treadmill test (3.2 km h(-1) at 4% gradient), walking distance, cardiopulmonary responses, leg pain and perceived exertion during NPW were compared to responses evoked by normal walking in 20 patients with intermittent claudication. The distance to onset of claudication pain (claudication distance: CD) and to maximum walking distance (MWD), heart rate (HR), expired gas parameters, leg pain (Borg's CR-10 Scale) and perceived exertion (Borg's Rating of Perceived Exertion: RPE Scale) were compared. RESULTS: CD increased significantly from a median (range) distance of 77 m (28-503) to 130 m (41-1080) and MWD increased significantly from 206 m (81-1078) to 285 m (107-1080) when patients used the Nordic poles (P=0.000). The level of leg pain at MWD was also significantly reduced during NPW (P=0.002). Perceived exertion at MWD did not increase despite an increase in cardiopulmonary work, as indicated by an increase in oxygen consumption (16.5%; P=0.000). CONCLUSION: These results show that NPW immediately enables patients with intermittent claudication to walk further with less pain, despite a higher workload. NPW might also be a useful exercise strategy for improving the cardiovascular fitness of patients with intermittent claudication.

Effect of upper- and lower-limb exercise training on circulating soluble adhesion molecules, hs-CRP and stress proteins in patients with intermittent claudication.

OBJECTIVES: To investigate the effects of exercise training on levels of circulating biomarkers associated with the progression of atherosclerosis and risk of cardiovascular events in patients with intermittent claudication. METHODS: Circulating levels of soluble adhesion molecules (sVCAM-1, sICAM-1, sE-selectin), high sensitivity C-reactive protein (hs-CRP) and stress proteins (Hsp60 and Hsp70) in patients randomised to a 24-week programme of arm- or leg-cranking exercise were compared with those in usual care controls. RESULTS: Arm and leg exercise similarly improved lower-limb aerobic exercise capacity (20% vs 19%, respectively; P<0.001) and maximum walking distance (30% vs 35%, respectively; P<0.001). Improvements in training limb-specific peak oxygen consumption were attenuated for patients in the highest vs lowest quartile for circulating sVCAM-1 levels at baseline (3% vs 25% respectively, P<0.001). Although circulating hs-CRP levels tended to be lower in the arm-cranking group (-1.55 [95% CI: -1.06 to -2.26]mgl(-1)), exercise training had no effect on circulating levels of soluble adhesion molecules or stress proteins. CONCLUSIONS: These findings suggest that high levels of circulating sVCAM-1 are associated with an attenuated exercise training response and that arm-cranking exercise may provide an effective stimulus for evoking systemic anti-inflammatory adaptations in patients with intermittent claudication.

Relative tolerance to upper- and lower-limb aerobic exercise in patients with peripheral arterial disease.

OBJECTIVES: To investigate the effects of peripheral arterial disease (PAD) on relative tolerance to upper- and lower-limb aerobic exercise. METHODS: Peak cardiorespiratory responses evoked by an incremental arm-cranking test (ACT) and an incremental leg-cranking test (LCT) were compared in patients with PAD (N=101; median age 69 year, range 50-85 years). Claudication distance (CD) and total distance before intolerable claudication pain (maximum walking distance: MWD) were also assessed during walking. RESULTS: Peak oxygen consumption (V O(2)) for the ACT was 94% of that measured for the LCT (1.01+/-0.03 versus 1.10+/-0.03lmin(-1), respectively; P<0.001), but in a significant proportion of patients (35%; P<0.001), exceeded that recorded for the LCT. The ratio of upper- to lower-limb peak V O(2) was higher (0.98+/-0.04 compared to 0.98+/-0.05lmin(-1) and 1.00+/-0.06 compared to 1.21+/-0.06lmin(-1); P<0.01), whereas walking performance (CD: 94+/-14 versus 187+/-25 m, P<0.01; MWD: 227+/-20 versus 394+/-33 m, P<0.01) was lower for patients in the lowest ankle to brachial pressure index quartile compared to patients in the highest quartile, respectively. CONCLUSION: Upper-limb aerobic conditioning could be a useful exercise stimulus for maintaining or improving cardiorespiratory function in patients with severe PAD as they have a greater relative upper-limb aerobic power.