Intramuscular pressure and tissue oxygenation during low‐force static contraction do not underlie muscle fatigue

Blangsted, Anne Katrine; Vedsted, P; Sjøgaard, Gisela; Søgaard, Karen

doi:10.1111/j.1365-201x.2005.01411.x

Cited by 32 publications

(26 citation statements)

References 59 publications

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“…In spite of this, the authors confirmed fatigue development largely based on accompanying patterns for mechanographic RMS and MPF signals, which changed impressively. In the study by Blangsted et al (2005) no explanation was provided for the oxygenation trend they observed. It may be of interest to note that the oxygenation trend in our data behaved similarly to this previous study, however, we attribute our increases to the activity involved with the pauses and in the Blangsted et al (2005) study no pauses were implemented.…”

Section: Discussionmentioning

confidence: 75%

“…In the study by Blangsted et al (2005) no explanation was provided for the oxygenation trend they observed. It may be of interest to note that the oxygenation trend in our data behaved similarly to this previous study, however, we attribute our increases to the activity involved with the pauses and in the Blangsted et al (2005) study no pauses were implemented. Therefore, it is reasonable that our data and their data were not driven by the same mechanisms.…”

Section: Discussionmentioning

confidence: 75%

“…Hicks et al (1999) reported no change in oxygenation during 2 min of sustained forearm flexion at 10% MVC, however, the median power frequency throughout the contraction declined. In a recent study, Blangsted et al (2005) showed a drop in the oxygenation initially after the onset of a 10% MVC of the biceps brachii that was followed by a return to baseline throughout a 10 min sustained contraction period. EMG amplitude did not change in time and only a slight decline in EMG mean frequency was observed.…”

Section: Discussionmentioning

confidence: 97%

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Oxygenation, EMG and position sense during computer mouse work. Impact of active versus passive pauses

2006

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We investigated the effects of active versus passive pauses implemented during computer mouse work on muscle oxygenation and EMG of the forearm extensor carpi radialis muscle, and on wrist position sense. Fifteen healthy female subjects (age: 19-24 years) performed a 60-min mouse-operated computer task, divided into three 20 min periods, on two occasions separated by 3-6 days. On one occasion a passive pause (subjects resting) was implemented at the end of each 20-min period, and on another occasion an active pause (subjects performed a number of high intensity extensions of the forearm) was implemented. Also at the end of each 20-min period, test contractions were conducted and subjective ratings of fatigue and stress were obtained. Another parameter of interest was total haemoglobin calculated as the summation of oxy-and deoxy-haemoglobin, since it reflects blood volume changes. The most interesting findings were an overall increasing trend in total haemoglobin throughout the mouse work (P<0.001), and that this trend was greater for the active pause as compared to the passive pause (P<0.01). These data were accompanied by an overall increase in oxygen saturation (P<0.001), with a tendency, albeit not significant, toward a higher increase for the active pause (P=0.13). EMG amplitude and median frequency tended to decrease (P=0.08 and 0.05, respectively) during the mouse work but was not different between pause types. Borg ratings of forearm fatigue showed an overall increase during the activity (P<0.001), but the perceptions of stress did not change. Position sense did not change due to the mouse work for either pause type. While increasing trends were found for both pause types, the present study lends support to the hypothesis of an enhancement in oxygenation and blood volume for computer mouse work implemented with active pauses. However, a presumption of an association between this enhancement and attenuated fatigue during the mouse work was not supported.

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Section: Discussionmentioning

confidence: 75%

Section: Discussionmentioning

confidence: 75%

Section: Discussionmentioning

confidence: 97%

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Oxygenation, EMG and position sense during computer mouse work. Impact of active versus passive pauses

2006

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“…However, there is no evidence of an insuYcient oxygen supply to muscle during low-load work (see Vollestad and Roe 2003;Blangsted et al 2005). It has nevertheless been speculated that decreased oxygenation locally in muscle may be a causal factor for increased lactate concentration found in response to low-load work (Rosendal et al 2004b).…”

Section: Discussionmentioning

confidence: 97%

Effects of 30 versus 60 min of low-load work on intramuscular lactate, pyruvate, glutamate, prostaglandin E2 and oxygenation in the trapezius muscle of healthy females

et al. 2006

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The aim of this study was to investigate the effects of duration of low-load repetitive work on intramuscular lactate, pyruvate, glutamate and prostaglandin E(2) (PGE(2)), and oxygen saturation in the trapezius muscle. Twenty healthy females were studied during baseline rest, during low-load repetitive work for either 30 (REP 30) or 60 min (REP 60) and 60 min recovery. Intramuscular microdialysate (IMMD) samples were obtained, and local muscle tissue oxygenation (%StO(2)) assessed with near-infrared spectroscopy (NIRS). Subjects rated their perceived exertion (Borg CR-10 scale) and capillary blood was sampled for lactate analysis. The results showed a significant increase in IMMD lactate in response to both REP 30 and REP 60 (P < 0.05 and P < 0.01, respectively) and glutamate (P < 0.0001), but no progressive increase with increasing work duration. Both IMMD pyruvate and lactate tended to be significantly increased during the recovery period. No corresponding increase in blood lactate was found. Local muscle %StO(2) did not change significantly in response to work and was not correlated to the IMMD lactate concentration. The ratings of perceived exertion increased in response to work, and remained increased after recovery for REP 60. In conclusion, the results of this study show significantly increased IMMD lactate and, glutamate concentrations in the trapezius muscle of healthy females in response to low-load work, but no progressive increase with increased work duration. Further, they do not indicate that the increased IMMD lactate concentration was caused by a locally decreased or insufficient muscle tissue oxygenation.

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“…EMG recordings of the trapezius were made during a 15-s test contraction at 30% MVC. With respect to the force level of the test contraction, a previous study has demonstrated that low-frequency fatigue due to a lowforce continuous task is more successfully extracted from EMG signals at 5% MVC than at 80% MVC (Blangsted et al 2005b). The lower the force at which the contraction is recorded by EMG, the more diYcult the extraction of EMG signals; however, higher force contractions create a larger inXuence of fatigue on the measurement.…”

Section: Emg Recording and Analysismentioning

confidence: 97%

Electromyogram and perceived fatigue changes in the trapezius muscle during typewriting and recovery

et al. 2007

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The purpose of the present study was to investigate the development and recovery of muscle fatigue in the upper trapezius muscle by analyzing electromyographic signals. Six male subjects performed a simulated typewriting task for four 25-min sessions. During fatigue and the following rest periods, subjective fatigue and surface electromyography (EMG) from the trapezius muscle during isometric contraction at 30% maximum voluntary contraction (MVC) were periodically measured in the interval. We detected a significant decrease in muscle fiber conduction velocity (MFCV) (P = 0.008) and median frequency (MDF) (P = 0.026) as well as an increase in root mean square (RMS) (P = 0.039) and subjective fatigue (P = 0.0004) during the fatigue period. During the recovery period, subjective fatigue decreased drastically and significantly (P = 0.0004), however, the EMG parameters did not recover completely. Thus, physiological muscle fatigue in the trapezius developed in accordance with subjective muscle fatigue during typewriting. On the other hand, differences between the physiological and subjective parameters were found during recovery. Further studies should be necessary to reveal the discrepancy could be a major factor of a transition from temporal phenomena to serious chronic muscle fatigue and to identify the necessity of some guidelines to prevent VDT work-related chronic muscle fatigue in the trapezius.

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Intramuscular pressure and tissue oxygenation during low‐force static contraction do not underlie muscle fatigue

Cited by 32 publications

References 59 publications

Oxygenation, EMG and position sense during computer mouse work. Impact of active versus passive pauses

Oxygenation, EMG and position sense during computer mouse work. Impact of active versus passive pauses

Effects of 30 versus 60 min of low-load work on intramuscular lactate, pyruvate, glutamate, prostaglandin E2 and oxygenation in the trapezius muscle of healthy females

Electromyogram and perceived fatigue changes in the trapezius muscle during typewriting and recovery

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