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| 2. |
- Elcadi, Guilherme H.
(författare)
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Near infrared spectroscopy for assessing oxygenation and hemodynamics in the upper extremities of healthy subjects and patients with work-related muscle pain
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The prevalence of work-related muscle pain (WRMP) is large in the general population in the industrialized world. Despite significant advances over recent years in some research areas, the mechanisms of why WRMP occurs and the pathophysiological mechanisms behind the disorders are still unclear. One suggested explanation is that WRMP is caused initially by a limitation of the local muscle circulation and oxidative metabolism. There is a lack of objective methods to gauge the development and diagnosis of WRMP. Near infrared spectroscopy (NIRS) is a non-invasive technique that allows for determinations of oxygenation and blood flow. The purpose of this thesis was to evaluate NIRS (1) as a method for measuring muscle oxygenation and hemodynamics for the extensor carpi radialis (ECR) and trapezius descendens muscles (TD), and (2) to investigate whether variables measured by NIRS differed between patients diagnosed with WRMP and healthy subjects. Several variables of NIRS were produced and investigated. These included muscle oxygenation (StO2%), changes during contractions (∆StO2%) and StO2% recovery (Rslope), total hemoglobin (HbT) as an indication of blood volume and its changes during contractions (∆HbT). In addition, for the ECR, by applying an upper arm venous occlusion (VO) HbTslope increase as a surrogate of blood flow, and for both VO and arterial occlusion (AO) HHbslope increase (i.e. deoxyhemoglobin slope) as a surrogate of oxygen consumption were variables of interest. A first objective was to determine how StO2% and HbT responded to various contraction forces and how it related to muscle activation measured by electromyography (EMG). For both muscles isometric contractions of 10, 30, 50 and 70% of maximal voluntary contraction (MVC) were maintained for 20 s each by healthy males and females; additionally a 10% MVC contraction was sustained for 5 min. For the different contraction levels, predictable relationships were seen between ∆StO2% and force, and between ∆StO2% and EMG RMS amplitude. The general trend was a decrease in ∆StO2% with increasing force and increasing EMG. Females showed a tendency for a higher oxygen use (i.e., drop in StO2%) for the ECR over force levels than males and a higher RMS% MVC for the TD. For the 10% MVC contraction sustained for 5 min gender specific changes over time for HbT and RMS for the ECR, and for StO2% for the TD muscle were seen. A second objective was to determine the day-to-day reliability of NIRS variables for the ECR and TD muscles at group level (Pooled data) and at gender level (males and females). Measurements were performed on two occasions separated by 4-6 days and intraclass correlation coefficients (ICC) and limits of agreement (LOA) were determined as reliability and reproducibility indicators, respectively. Variables tested were ∆StO2% during submaximal isometric contractions of 10, 30, 50 and 70% MVC and StO2% recovery (Rslope) after contractions and after AO. For the ECR, HbTslope as an indication of blood flow (using VO) and HHbslope as a surrogate of oxygen consumption for both VO and AO were computed. For ∆StO2% for the ECR the highest ICC was at 30% MVC for both the pooled data and at gender level. For the TD ICCs were comparably high for 30, 50, 70 % MVC (for both muscles the ∆StO2% at 10% MVC showed the lowest ICC). Further, females showed a higher ICC than males for contraction levels of 50 and 70% MVC. For both muscles, LOA for ∆StO2% was lowest at 10% and highest at 50 and 70% MVC. For the ECR Rslope ICCs were high for all contraction levels, but was lower for AO; LOA was lowest at 70% MVC. For the TD, Rslope ICCs were also high for all contraction levels and LOA was lowest at 30 % MVC. ICC for HbTslope was the lowest of all variables tested. For HHbslope ICC was higher for AO than for VO, and LOA was lower for AO. A third objective was to determine if there were differences between healthy subjects and patients diagnosed with WRMP in ∆StO2% and ∆HbT responses during varying submaximal contractions (10, 30, 50 and 70% MVC), and StO2% recovery (Rslope) immediately after contractions and AO. Additional variables tested in the ECR at rest were HHbslope to indicate oxygen consumption (using AO) and HbTslope as an indication of blood flow. There were no differences between groups in ∆StO2% and ∆HbT variables during the contractions or Rslope in the recovery after contractions or AO. Furthermore, HbTslope was not different between groups However, oxygen consumption for the ECR and StO2% for the TD at rest were significantly greater for healthy subjects compared to patients. A fourth objective was to determine if there were differences in StO2% and HbT between healthy subjects and WRMP patients during a 12 min sustained contraction of 15 % MVC. In addition, the protocol included a recovery period of 30 min. Prior to contraction, as well as during the recovery period, HbTslope as a surrogate of blood flow was determined for the ECR. Neither the ECR nor the TD exhibited significant differences between groups for StO2% and HbT during the contraction. For the TD patients showed a lower StO2% value at rest and throughout the contraction than healthy subjects. For the ECR HbT during the sustained contraction the general trend was an initial decrease with gradual increase throughout the contraction for both groups. For HbTslope no differences were seen between patients and healthy subjects before the sustained contraction and during the recovery period for both muscles.NIRS is deemed a suitable technique for assessing physiological measurements of the upper extremity, including for day-to-day testing.NIRS was not able to distinguish between the patients with WRMP and controls. A concern in the thesis is the characteristics of the patient group in being equally active in recreational sports, actively working, and similar in muscle strength as controls. Thus, applying NIRS for studying a more severe patient group could yield different results.
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| 3. |
- Elcadi, Guilherme H, 1966-, et al.
(författare)
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No differences in oxygenation in the forearm and shoulder of patients with work-related muscle pain and healthy subjects during a low-load sustained contraction
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- A frequently ascribed symptom associated to work-related muscle pain (WRMP) is muscle fatigue. Studies investigating oxygenation and hemodynamics in association to fatigue development in the muscles of patients with WRMP are sparse. Inadequate oxygen consumption and/or inadequate blood supply can influence the ability of the muscles to withstand fatigue. In this study we applied near-infrared spectroscopy (NIRS) and electromyography (EMG) to investigate oxygenation, hemodynamics and muscle activity in the extensor carpi radialis (ECR) and trapezius (TD) muscles of patients with WRMP and healthy controls. Eighteen patients with diffuse neck-shoulder-arm pain and 17 controls (matched in age and sex) were equipped with NIRS and EMG probes. After determination of maximal voluntary contraction (MVC) a sustained contraction of 15% MVC was performed with a cutoff for the maximum time of 12 min. Variables generated were StO2% and HbT from NIRS and RMS%max and MPF from EMG during the contraction. T tests and Mann-Whitney tests were used for analyzes of differences in MVC and endurance times. Full factorial repeated measures analyses of variance (ANOVA) were used to assess differences between patients and controls in NIRS and EMG parameters over time. Results showed no differences in MVC between patients and controls. We found, however, a shorter endurance time for patients compared to controls. There were no significant differences in StO2%, HbT, RMS and MPF responses during contraction between groups for the ECR. For the TD there was a group effect for StO2% with patients showing a lower level at rest and throughout the contraction. For the ECR and TD oxygenation, hemodynamics, RMS and MPF there were no straightforward differences between patients and controls that could explain the differences in endurance time. Therefore, we conclude that the shorter endurance time seen in the present study was not measurable by physiological indicators investigated in this group of patients.
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| 4. |
- Elcadi, Guilherme H, et al.
(författare)
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No differences in oxygenation in the forearm and shoulder of patients with work-related muscle pain and healthy subjects during a low-load sustained contraction
- 2013
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- A frequently ascribed symptom associated to work-related muscle pain (WRMP) is muscle fatigue. Studies investigating oxygenation and hemodynamics in association to fatigue development in the muscles of patients with WRMP are sparse. Inadequate oxygen consumption and/or inadequate blood supply can influence the ability of the muscles to withstand fatigue. In this study we applied near-infrared spectroscopy (NIRS) and electromyography (EMG) to investigate oxygenation, hemodynamics and muscle activity in the extensor carpi radialis (ECR) and trapezius (TD) muscles of patients with WRMP and healthy controls. Eighteen patients with diffuse neck-shoulder-arm pain and 17 controls (matched in age and sex) were equipped with NIRS and EMG probes. After determination of maximal voluntary contraction (MVC) a sustained contraction of 15% MVC was performed with a cutoff for the maximum time of 12 min. Variables generated were StO2% and HbT from NIRS and RMS%max and MPF from EMG during the contraction. T tests and Mann-Whitney tests were used for analyzes of differences in MVC and endurance times. Full factorial repeated measures analyses of variance (ANOVA) were used to assess differences between patients and controls in NIRS and EMG parameters over time. Results showed no differences in MVC between patients and controls. We found, however, a shorter endurance time for patients compared to controls. There were no significant differences in StO2%, HbT, RMS and MPF responses during contraction between groups for the ECR. For the TD there was a group effect for StO2% with patients showing a lower level at rest and throughout the contraction. For the ECR and TD oxygenation, hemodynamics, RMS and MPF there were no straightforward differences between patients and controls that could explain the differences in endurance time. Therefore, we conclude that the shorter endurance time seen in the present study was not measurable by physiological indicators investigated in this group of patients.
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| 5. |
- Elcadi, Guilherme H., 1966-, et al.
(författare)
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Oxygenation and Hemodynamics Do Not Underlie Early Muscle Fatigue for Patients with Work-Related Muscle Pain
- 2014
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Ingår i: PLOS ONE. - : PLOS (Public library of science). - 1932-6203. ; 9:4
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Tidskriftsartikel (refereegranskat)abstract
- Patients suffering from work-related muscle pain (WRMP) fatigue earlier during exercise than healthy controls. Inadequate oxygen consumption and/ or inadequate blood supply can influence the ability of the muscles to withstand fatigue. However, it remains unknown if oxygenation and hemodynamics are associated with early fatigue in muscles of WRMP patients. In the present study we applied near-infrared spectroscopy (NIRS) on the extensor carpi radialis (ECR) and trapezius (TD) muscles of patients with WRMP (n = 18) and healthy controls (n = 17). Our objective was to determine if there were group differences in endurance times for a low-level contraction of 15% maximal voluntary contraction (MVC) -sustained for 12-13 min, and to see if these differences were associated with differences in muscle oxygenation and hemodynamics. At baseline, oxygen saturation (StO(2)%) was similar between groups for the ECR, but StO2% was significantly lower for TD for the WRMP patients (76%) compared to controls (85%) (P < 0.01). Also, baseline ECR blood flow was similar in the two groups. For both muscles there were a larger number of patients, compared to controls, that did not maintain the 15% MVC for the allotted time. Consequently, the endurance times were significantly shorter for the WRMP patients than controls (medians, ECR: 347 s vs. 582 s; TD: 430 s vs. 723 s respectively). Responses in StO(2)% during the contractions were not significantly different between groups for either muscle, i.e. no apparent difference in oxygen consumption. Overall, we interpret our findings to indicate that the early fatigue for our WRMP patients was not associated with muscle oxygenation and hemodynamics.
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| 7. |
- Elcadi, Guilherme H., 1966-, et al.
(författare)
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Shoulder and forearm oxygenation and myoelectric activity in patients with work related muscle pain and healthy subjects
- 2013
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Ingår i: European Journal of Applied Physiology. - New York : Springer. - 1439-6319 .- 1439-6327. ; 113:5, s. 1103-1115
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Tidskriftsartikel (refereegranskat)abstract
- We tested hypotheses of (i) reduced oxygen usage, oxygen recovery, blood flow and oxygen consumption; and (ii) increased muscle activity for patients diagnosed with work related muscle pain in comparison to healthy controls. Oxygenation was measured with near infrared spectroscopy (NIRS), and muscle activity with EMG for the extensor carpi radialis (ECR) and trapezius descendens (TD) muscles. Eighteen patients with diffuse neck-shoulder-arm pain and seventeen controls (matched in age and sex) were equipped with NIRS and EMG probes. After determining an individual’s maximum voluntary contraction (MVC) force, short term (20 sec) isometric contractions for the ECR and TD of 10%, 30%, 50% and 70% MVC generated ∆StO2% and StO2% recovery (Rslope) from NIRS, and RMS%max from EMG signals. In addition, upper arm venous (VO) and arterial (AO) occlusions generated slopes of total hemoglobin (HbTslope) and deoxyhemoglobin (HHbslope) for the resting ECR as surrogates of blood flow and oxygen consumption, respectively. Mixed Model analyses, t-tests, and Mann-Whitney test were used to assess differences between groups. There was no significant difference in MVC between groups for either muscle. Also, ∆StO2%, Rslope for either muscle, and ECR-HbTslope were not different between groups, thus our hypotheses of reduced oxygen use, recovery, and blood flow for patients were not confirmed. However, patients had a significantly lower ECR-HHbslope confirming our hypothesis of reduced consumption. Further, there was no difference in RMS%max during contractions meaning that the hypothesis of increased activity for patients was not confirmed. When taking into account the number of NIRS variables studied, differences we found between our patient group and healthy controls (i.e. in forearm oxygen consumption and shoulder oxygen saturation level) may be considered modest. Overall our findings may have been impacted by the fact that our patients and controls were similar in muscle strength, which is in contrast to previous studies.
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| 8. |
- Elcadi, Guilherme H., 1966-, et al.
(författare)
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The relationship between oxygenation and myoelectric activity in the forearm and shoulder muscles of males and females
- 2011
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Ingår i: European Journal of Applied Physiology. - : Springer. - 1439-6319 .- 1439-6327. ; 111, s. 647-658
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Tidskriftsartikel (refereegranskat)abstract
- The aim was to investigate the relationship between oxygen saturation (StO(2)%) measured with near-infrared spectroscopy (NIRS) and myoelectric activity (root mean square, RMS) for the extensor carpi radialis (ECR) and trapezius muscles. In addition, gender differences were examined for submaximal (10-70% MVC) and sustained (10% MVC for 5 min) isometric contractions. Thirteen males and 15 females participated. Changes in StO(2)% (a dagger StO(2)%) and RMS, expressed as percentages of maximum, were calculated for each submaximal contraction. A good correlation between a dagger StO(2)% and RMS was seen for the ECR (r = -0.53) and a moderate correlation seen for the trapezius muscle (r = -0.44). The ANOVA showed a significant decrease in ECR-a dagger StO(2)% over force with females demonstrating a tendency for larger changes than males. ECR-RMS increased over force with no impact of gender. For the trapezius, a dagger StO(2)% decreased over force but was not gender dependent. Trapezius-RMS increased over force with females demonstrating a tendency for greater change than males. For the sustained contraction, ECR-StO(2)% changed over time but was not gender dependent. ECR-RMS increased over time with females showing a greater response than males. Trapezius-StO(2)% changed over time and differed between genders, i.e., males increased while females decreased. RMS increased over time similarly for both genders. In conclusion, our data show that the ECR and trapezius aerobic demands during isometric contractions are negatively correlated to electromyography (EMG) RMS. The present study also suggests some gender specificity for forearm and shoulder myoelectric activity and oxygenation for submaximal and sustained contractions.
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