Effects of Exercise Training on Calf Tissue Oxygenation in Men With Intermittent Claudication

Near infrared spectroscopy in peripheral artery disease and the diabetic foot: A systematic review

With the need for tools that assess microvascular status in diabetic foot disease (DFD) being clear, near infrared spectroscopy (NIRS) is a putative method for noninvasive testing of the diabetic foot. The use of NIRS in patients with peripheral arterial disease (PAD) has extended to its role in studying the pathophysiology of DFD. NIRS generates metrics such as recovery time, deoxygenation, oxygen consumption (VO₂ ), tissue oxygen saturation (StO₂ ), total haemoglobin (HbT), and oxyhaemoglobin area under the curve (O₂ Hb_AUC ). NIRS may potentially help the multidisciplinary team stratify limbs as high-risk, especially in diabetic patients with symptoms masked by peripheral neuropathy. NIRS may be useful for assessing treatment effectiveness and preventing deterioration of patients with PAD.

The Use of Near Infrared Spectroscopy to Evaluate the Effect of Exercise on Peripheral Muscle Oxygenation in Patients with Lower Extremity Artery Disease: A Systematic Review

OBJECTIVE

Near infrared spectroscopy (NIRS) has been suggested as a new diagnostic tool in patients with lower extremity artery disease (LEAD). The aim of this systematic review was to summarise the impact of exercise therapy on lower limb muscle oxygenation, evaluated by NIRS, in patients with LEAD, and to give an overview on NIRS instruments and methodology.

DATA SOURCES

MEDLINE and Embase.

REVIEW METHODS

A systematic search was conducted in MEDLINE and Embase, from the earliest date available until 16 March 2020, to identify peer reviewed studies involving the use of NIRS in the evaluation of exercise training on muscle oxygenation in patients with LEAD. Primary outcomes were NIRS derived variables during treadmill exercise. Effect sizes were calculated as standardised mean differences. Assessment of methodological quality was done using a combined checklist from the Cochrane bias and the quality assessment tool for before and after studies without a control group.

RESULTS

Eleven original trials were included involving 16 exercise groups and four control groups. Tissue saturation index (TSI) at rest remained unchanged following the exercise interventions. Exercise training increased time to minimum TSI during exercise (range effect sizes: +0.172 to +0.927). In addition, exercise training led to a faster recovery to half and full TSI rest values in most intervention groups (range effect sizes -0.046 to -0.558 and -0.269 to -0.665, respectively). Finally, NIRS data reproducibility and analytic methods were under reported in the included studies.

CONCLUSION

The available data suggest that exercise training improves de-oxygenation and re-oxygenation patterns, as measured with NIRS, in patients with LEAD. Whereas NIRS is a promising tool in the evaluation of LEAD, the low number of randomised controlled trials, as well as large heterogeneity in NIRS assessment methods, outcome measures, and instrumentation, warrants more research to better understand the role of muscle oxygenation associated with exercise induced improvements in walking capacity.

Walking performances and muscle oxygen desaturation are increased after supervised exercise training in Takayasu arteritis: a case report and a review of the literature

Background

Takayasu arteritis (TAK) is a rare chronic inflammatory vasculitis predominantly affecting the aorta and its main branches. Takayasu arteritis has been shown to increase cardiovascular risk. Supervised exercise training (SET) is a well-recognized and effective therapeutic tool improving walking performances in patients with chronic atherosclerotic disease; however, the effects of SET, and the underlying mechanisms, remain poorly documented in TAK patients.

Case summary

We reviewed the literature and investigated the effects of a 12-week SET programme on walking performances, physical function, and calf muscle oxygen saturation (StO₂; assessed by near-infrared spectroscopy) during exercise in a 28-year-old man with TAK and symptoms of arterial lower limb claudication. The literature review evidences only two recent publications suggesting that exercise training is effective and well-tolerated in patients with arteritis. The treadmill pain-free (+22%) and maximal (+273%) walking distance, 6-min walking distance (+66%), and physical function of lower extremities (+20%) following SET were significantly improved in our patient. Moreover, we observed a greater muscle oxygen desaturation (increased oxygen extraction) during exercise.

Discussion

Following SET, the increased oxygen extraction may be related to improved microvascular milieu leading to a better match between muscle oxygen supply and demand during exercise. These new results may contribute to mechanistic insights in peripheral adaptations following exercise training in TAK patients and may help to explain, at least partly, the increased walking performances. Although more studies are needed to better explore the impact of exercise training, these results suggest that exercise should be recommended in TAK patients.

Effects of exercise training on calf muscle oxygen extraction and blood flow in patients with peripheral artery disease

We employed near-infrared optical techniques, diffuse correlation spectroscopy (DCS), and frequency-domain near-infrared spectroscopy (FD-NIRS) to test the hypothesis that supervised exercise training increases skeletal muscle microvascular blood flow and oxygen extraction in patients with peripheral artery disease (PAD) who experience claudication. PAD patients ( n = 64) were randomly assigned to exercise and control groups. Patients in the exercise group received 3 mo of supervised exercise training. Calf muscle blood flow and oxygen extraction were optically monitored before, during, and after performance of a graded treadmill protocol at baseline and at 3 mo in both groups. Additionally, measurements of the ankle-brachial index (ABI) and peak walking time (PWT) to maximal claudication were made during each patient visit. Supervised exercise training was found to increase the maximal calf muscle blood flow and oxygen extraction levels during treadmill exercise by 29% (13%, 50%) and 8% (1%, 12%), respectively [ P < 0.001; median (25th percentile, 75th percentile)]. These improvements across the exercise group population were significantly higher than corresponding changes in the control group ( P < 0.004). Exercise training also increased PWT by 49% (18%, 101%) ( P = 0.01). However, within statistical error, the ABI, resting calf muscle blood flow and oxygen extraction, and the recovery half-time for hemoglobin\myoglobin desaturation following cessation of maximal exercise were not altered by exercise training. The concurrent monitoring of both blood flow and oxygen extraction with the hybrid DCS/FD-NIRS instrument revealed enhanced muscle oxidative metabolism during physical activity from exercise training, which could be an underlying mechanism for the observed improvement in PWT. NEW & NOTEWORTHY We report on noninvasive optical measurements of skeletal muscle blood flow and oxygen extraction dynamics before/during/after treadmill exercise in peripheral artery disease patients who experience claudication. The measurements tracked the effects of a 3-mo supervised exercise training protocol and revealed that supervised exercise training improved patient ability to increase microvascular calf muscle blood flow and oxygen extraction during physical activity.

Blood pressure and calf muscle oxygen extraction during plantar flexion exercise in peripheral artery disease

Peripheral artery disease (PAD) is an atherosclerotic vascular disease that affects 200 million people worldwide. Although PAD primarily affects large arteries, it is also associated with microvascular dysfunction, an exaggerated blood pressure (BP) response to exercise, and high cardiovascular mortality. We hypothesized that fatiguing plantar flexion exercise that evokes claudication elicits a greater reduction in skeletal muscle oxygenation (SmO₂) and a higher rise in BP in PAD compared with age-matched healthy subjects, but low-intensity steady-state plantar flexion elicits similar responses between groups. In the first experiment, eight patients with PAD and eight healthy controls performed fatiguing plantar flexion exercise (from 0.5 to 7 kg for up to 14 min). In the second experiment, seven patients with PAD and seven healthy controls performed low-intensity plantar flexion exercise (2.0 kg for 14 min). BP, heart rate (HR), and SmO₂ were measured continuously using near-infrared spectroscopy (NIRS). SmO₂ is the ratio of oxygenated hemoglobin to total hemoglobin, expressed as a percent. At fatigue, patients with PAD had a greater increase in mean arterial BP (18 ± 2 vs. vs. 10 ± 2 mmHg, P = 0.029) and HR (14 ± 2 vs. 6 ± 2 beats/min, P = 0.033) and a greater reduction in SmO₂ (-54 ± 10 vs. -12 ± 4%, P = 0.001). However, both groups had similar physiological responses to low-intensity, nonpainful plantar flexion exercise. These data suggest that patients with PAD have altered oxygen uptake and/or utilization during fatiguing exercise coincident with an augmented BP response.NEW & NOTEWORTHY In this laboratory study, patients with peripheral artery disease performed plantar flexion exercise in the supine posture until symptoms of claudication occurred. Relative to age- and sex-matched healthy subjects we found that patients had a higher blood pressure response, a higher heart rate response, and a greater reduction in skeletal muscle oxygenation as determined by near-infrared spectroscopy. Our data suggest that muscle ischemia contributes to the augmented exercise pressor reflex in peripheral artery disease.

Efficacy of treadmill exercises on arterial blood oxygenation, oxygen consumption and walking distance in healthy elderly people: a controlled trial

Background

Regular physical exercise and healthy lifestyle can improve aerobic power of the elderly, although lung capacity gradually deteriorates with age. The aims of the study are: a) to evaluate the therapeutic effect of a treadmill exercise program on arterial blood oxygenation (SaO₂), maximum oxygen consumption (VO_2max) and maximum walking distance (MWD) in healthy elderly people; b) to examine the outcome of the program at a supervised short-term and at an unsupervised long-term.

Methods

A prospective, not-randomized controlled intervention trial (NRCT) was conducted. Eighty participants were allocated into two homogeneous groups (training group, TG, n = 40; control group, CG, n = 40). Each group consisted of 20 men and 20 women. Pre-intervention measures of SaO₂, VO_2max and MWD were taken of each participant 1-week before the training program to establish the baseline. Also, during the training program, the participants were followed up at the 12, 30 and 48th week. The exercise program consisted of walking on a treadmill with fixed 0 % grade of inclination 3 times weekly for 48 weeks; the first 12 weeks were supervised and the remaining 36 weeks of the program were unsupervised. Participants in the control group were encouraged to walk twice a week during 45 min, and received standard recommendations for proper health.

Results

Related to the baseline, the SaO_2, VO_2max, and MWD is greater in the intervention group at the 12^th (p <.001), 30^th (p <.001) and 48^th week (p <.001). Compared with the control group, there was also a significant improvement of SaO_2, VO_2max, and MWD valuesin the intervention group (p <.001) at the 12^th (p <.001), 30^th (p <.001) and 48^th week (p <.001). Supervised intervention shows greater improvement of SaO_2, VO_2max, and MWD values than in the unsupervised one.

Conclusion

These results show that performing moderate exercise, specifically walking 3 days a week, is highly recommended for healthy older people, improving aerobic power.

Trial registration

Current Controlled Trials ISRCTN12621097.

[Vascular rehabilitation in patients with peripheral arterial disease]

Lower limb peripheral arterial disease (PAD) is a frequent debilitating disease associated with a high morbidity and mortality rate. The benefit of rehabilitation in PAD patients has been largely demonstrated, both for patients that undergo amputation, and for patients with claudication. In these latter patients, rehabilitation programs rely on a variety of additional techniques or tools, among which: stretching, specific muscle proprioception, walking and a variety of other physical activities, exercise or situations adapted to community life, lower limb and respiratory physiotherapy, patient's education, support for smoking cessation and healthy nutrition, social support, etc. Whether rehabilitation is performed in specialised integrated structures or performed on a home-based basis, various clinicians are involved. Despite evidence-based proof of efficacy, rehabilitation of PAD patients with claudication is still under-used.

The Effects of Walking or Walking-with-Poles Training on Tissue Oxygenation in Patients with Peripheral Arterial Disease

This randomized trial proposed to determine if there were differences in calf muscle StO₂ parameters in patients before and after 12 weeks of a traditional walking or walking-with-poles exercise program. Data were collected on 85 patients who were randomized to a traditional walking program (n = 40) or walking-with-poles program (n = 45) of exercise training. Patients walked for 3 times weekly for 12 weeks. Seventy-one patients completed both the baseline and the 12-week follow-up progressive treadmill tests (n = 36 traditional walking and n = 35 walking-with-poles). Using the near-infrared spectroscopy measures, StO₂ was measured prior to, during, and after exercise. At baseline, calf muscle oxygenation decreased from 56 ± 17% prior to the treadmill test to 16 ± 18% at peak exercise. The time elapsed prior to reaching nadir StO₂ values increased more in the traditional walking group when compared to the walking-with-poles group. Likewise, absolute walking time increased more in the traditional walking group than in the walking-with-poles group. Tissue oxygenation decline during treadmill testing was less for patients assigned to a 12-week traditional walking program when compared to those assigned to a 12-week walking-with-poles program. In conclusion, the 12-week traditional walking program was superior to walking-with-poles in improving tissue deoxygenation in patients with PAD.

Effects of a 6-month exercise program pilot study on walking economy, peak physiological characteristics, and walking performance in patients with peripheral arterial disease

The purpose of this study was to examine the effects of a 6-month exercise program on submaximal walking economy in individuals with peripheral arterial disease and intermittent claudication (PAD-IC). Participants (n = 16) were randomly allocated to either a control PAD-IC group (CPAD-IC, n = 6) which received standard medical therapy, or a treatment PAD-IC group (TPAD-IC; n = 10) which took part in a supervised exercise program. During a graded treadmill test, physiological responses, including oxygen consumption, were assessed to calculate walking economy during submaximal and maximal walking performance. Differences between groups at baseline and post-intervention were analyzed via Kruskal–Wallis tests. At baseline, CPAD-IC and TPAD-IC groups demonstrated similar walking performance and physiological responses. Postintervention, TPAD-IC patients demonstrated significantly lower oxygen consumption during the graded exercise test, and greater maximal walking performance compared to CPAD-IC. These preliminary results indicate that 6 months of regular exercise improves both submaximal walking economy and maximal walking performance, without significant changes in maximal walking economy. Enhanced walking economy may contribute to physiological efficiency, which in turn may improve walking performance as demonstrated by PAD-IC patients following regular exercise programs.