Take the Direct Route When Evaluating Training Effects in Lower Extremity Arterial Disease: Use Near Infrared Spectroscopy!

Rationale Supervised treadmill exercise for claudication in peripheral arterial disease is effective but poorly tolerated because of ischemic leg pain. Near infrared spectroscopy allows non-invasive detection of muscle ischemia during exercise, allowing for characterization of tissue perfusion and oxygen utilization during training. Objective We evaluated walking time, muscle blood flow, and muscle mitochondrial capacity in patients with peripheral artery disease after a traditional pain-based walking program and after a muscle oxygen-guided walking program. Method and results Patients with peripheral artery disease trained thrice weekly in 40-minute-long sessions for 12 weeks, randomized to oxygen-guided training ( n = 8, age 72 ± 9.7 years, 25% female) versus traditional pain-based training ( n = 10, age 71.6 ± 8.8 years, 20% female). Oxygen-guided training intensity was determined by maintaining a 15% reduction in skeletal muscle oxygenation by near infrared spectroscopy rather than relying on symptoms of pain to determine exercise effort. Pain free and maximal walking times were measured with a 12-minute Gardner treadmill test. Gastrocnemius mitochondrial capacity and blood flow were measured using near infrared spectroscopy. Baseline pain-free walking time was similar on a Gardner treadmill test (2.5 ± 0.9 vs. 3.6 ± 1.0 min, p = 0.5). After training, oxygen-guided cohorts improved similar to pain-guided cohorts (pain-free walking time 6.7 ± 0.9 vs. 6.9 ± 1.1 min, p < 0.01 for change from baseline and p = 0.97 between cohorts). Mitochondrial capacity improved in both groups but more so in the pain-guided cohort than in the oxygen-guided cohort (38.8 ± 8.3 vs. 14.0 ± 9.3, p = 0.018). Resting muscle blood flow did not improve significantly in either group with training. Conclusions Oxygen-guided exercise training improves claudication comparable to pain-based training regimens. Adaptations in mitochondrial function rather than increases in limb perfusion may account for functional improvement. Increases in mitochondrial oxidative capacity may be proportional to the degree of tissue hypoxia during exercise.

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Influence of Flooring on Lower Extremity Blood Oxygenation and Volume during Prolonged Standing

Proceedings of the Human Factors and Ergonomics Society Annual Meeting ◽

10.1177/1071181319631088 ◽

2019 ◽

Vol 63 (1) ◽

pp. 1278-1282

Author(s):

Stephanie A. Wiltman ◽

Kenneth S. Pechtl ◽

Theodore J. Huppert ◽

April J. Chambers

Keyword(s):

Infrared Spectroscopy ◽

Lower Extremity ◽

Near Infrared Spectroscopy ◽

Near Infrared ◽

Mixed Effects ◽

Blood Oxygenation ◽

Occupational Hazard ◽

Prolonged Standing ◽

Positive Effect ◽

Hard Floor

Prolonged standing is an occupational hazard that may evoke many cardiovascular problems. This study investigates the effects of anti-fatigue mats on hemoglobin levels—related to blood pooling—in the lower extremities during prolonged standing. Fifteen subjects (6 M, 9 F; Age = 26 ± 3 years; BMI = 23.2 ± 2.5 kg/m2) stood for one hour on a hard floor and anti-fatigue mat. Oxygenated (HbO), deoxygenated (HbR), and total (HbT) hemoglobin levels were measured for the soleus muscle using near infrared spectroscopy. A mixed-effects model was performed indicating that time, flooring, and their interaction effect were significantly associated with levels of HbO (time, p<0.0001; floor, p=0.0056; interaction, p=0.0033), HbR (time, p<0.0001), and HbT (time, p<0.0001; floor, p=0.0060; interaction, p=0.0062). Results indicate that hemoglobin levels change with time, and flooring has an effect. Blood pooling seems to be the mechanism. Anti-fatigue mats may have a positive effect on cardiovascular outcomes.

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