The effect of electrical stimulation on leg muscle pump activity in spinal cord-injured and able-bodied individuals

Item does not contain fulltext7 p

Near-infrared spectroscopy in chronic progressive external ophthalmoplegia: adipose tissue thickness confounds decreased muscle oxygen consumption.

Item does not contain fulltex

In vivo quantitative near-infrared spectroscopy in skeletal muscle during incremental isometric handgrip exercise.

Item does not contain fulltextThe aim of this study was to investigate the performance of in vivo quantitative near-infrared spectroscopy (NIRS) in skeletal muscle at various workloads. NIRS was used for the quantitative measurement of O2 consumption (mVO2) in the human flexor digitorum superficialis muscle at rest and during rhythmic isometric handgrip exercise in a broad range of work intensities (10-90% MVC=maximum voluntary contraction force). Six subjects were tested on three separate days. No significant differences were found in mVO2 measured over different days with the exception of the highest workload. The within-subject variability for each workload measured over the three measurements days ranged from 15.7 to 25.6% and did not increase at the high workloads. The mVO2 was 0.14 +/- 0.01 mlO2 min-1 100 g-1 at rest and increased roughly 19 times to 2.68 +/- 0.58 mlO2 min-1 100 g-1 at 72% MVC. These results show that local muscle oxygen consumption at rest as well as during exercise at a broad range of work intensities can be measured reliably by NIRS, applied to a uniform selected subject population. This is of great importance as direct local measurement of mVO2 during exercise is not possible with the conventional techniques. The method is robust enough to measure over separate days and at various workloads and can therefore contribute to a better understanding of human physiology in both the normal and pathological state of the muscle

Quantitative measurement of oxygen consumption and forearm blood flow in patients with mitochondrial myopathies

Item does not contain fulltext6 p

Adipose tissue thickness affects in vivo quantitative near-IR spectroscopy in human skeletal muscle.

Item does not contain fulltextThe influence of adipose tissue thickness (ATT) on near-IR spectroscopy (NIRS) measurements in vivo was studied in the human flexor digitorum superficialis muscle at rest and during sustained isometric handgrip exercise. NIRS was used for the quantitative measurement of muscle O(2) consumption (mV.O(2)) and forearm blood flow (FBF) in 78 healthy subjects. Skinfold thickness ranged from 1.4 to 8.9 mm within the group. Resting mV.O(2) was 0.110.04 ml of O(2).min(-1).100 g(-1), and FBF was 1.280.82 ml.min(-1).100 ml(-1). There was a negative correlation (r=-0.70, P< or =0.01), indicating a decrease in mV.O(2) with increasing ATT. mV.O(2) in the 10 leanest subjects appeared to be twice as high as that in the 10 subjects with the highest ATT. A poor correlation (r=0.29, P< or =0.01) was found between ATT and FBF. The gender difference that we found for mV.O(2) was due to the difference in ATT between female and male subjects. No correlation was found between maximum voluntary contraction and mV.O(2), nor between maximum voluntary contraction and ATT, indicating that the contraction force did not confound our results. These results show that ATT has a substantial confounding influence on in vivo NIRS measurements, and that it is essential to incorporate this factor into future NIRS muscle studies in order to justify comparisons between different groups. To facilitate such comparisons, upper and lower boundaries for normal values of mV.O(2) and FBF in relation to ATT are presented

Blood flow and muscle oxygen uptake at the onset and end of moderate and heavy dynamic forearm exercise.

Item does not contain fulltextWe hypothesized that forearm blood flow (FBF) during moderate intensity dynamic exercise would meet the demands of the exercise and that postexercise FBF would quickly recover. In contrast, during heavy exercise, FBF would be inadequate causing a marked postexercise hyperemia and sustained increase in muscle oxygen uptake (VO(2musc)). Six subjects did forearm exercise (1-s contraction/relaxation, 1-s pause) for 5 min at 25 and 75% of peak workload. FBF was determined by Doppler ultrasound, and O(2) extraction was estimated from venous blood samples. In moderate exercise, FBF and VO(2musc) increased within 2 min to steady state. Rapid recovery to baseline suggested adequate O(2) supply during moderate exercise. In contrast, FBF was not adequate during heavy dynamic exercise. Immediately postexercise, there was an approximately 50% increase in FBF. Furthermore, we observed for the first time in the recovery period an increase in VO(2musc) above end-exercise values. During moderate exercise, O(2) supply met requirements, but with heavy forearm exercise, inadequate O(2) supply during exercise caused accumulation of a large O(2) deficit that was repaid during recovery

Validation of measurement protocols to assess oxygen consumption and blood flow in the human forearm by near infrared spectroscopy

Item does not contain fulltext11 p

L carnitine and creatine in Friedreich's ataxia. A randomized, placebo-controlled crossover trial.

Contains fulltext : 48638.pdf (publisher's version ) (Closed access