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Introduction: Hamstring injuries are among the most common injuries in soccer players. Especially the danger of hamstring injuries increases in the final third of each half, with the biceps femoris muscle being highly susceptible, but currently there is no supporting evidence in soccer players. It is important to investigate to provide a basis for further clinical investigations in order to reduce the risk of hamstring injuries.
Objective: To investigate a soccer-specific muscle fatigue protocol has an effect on the activation patterns of the biceps and semitendinosus muscles and correlates with the subjectively perceived exertion of the soccer players.
Methods: 19 healthy soccer players aged 19 - 35 years were included and underwent a standardized procedure that included: (1) performance of the nordic hamstring curls (NHC) and a 10m sprint (pre-test), (2) a soccer-specific muscle fatigue loading protocol for 30 minutes with subsequent rating of perceived exertion (RPE), (3) re-assessed like pre-assessment (post- test). Electromyography (EMG) data were recorded the biceps and
semitendinosus muscles of both legs. Two parameters were analyzed: the peak amplitude during the NHC and the mean amplitude during the 10m sprint.
Results: The RPE score (9.5, p<0.001) and 10m sprint shows significant differences between pre- and post- test for the biceps (standing leg: -82.45, kicking leg: -81.77; p<0.01) and semitendinosus muscle (standing leg: -60.08, p=0.001); kicking leg: -65.30, p=0.03). Significant correlation exists between RPE score and biceps muscles at posttest (standing leg: r=-0.54, kicking leg: r=-0.51; p<0.05).
Conclusion: Muscle fatigue leads to significant changes in the activation behavior of the hamstring muscles. In particular, the biceps muscle shows a correlation with perceived exertion, the higher the exertion, the lower the muscle activity. This may help explain the higher prevalence of the biceps muscle in hamstring injuries and offers a basis for further clinical investigations
Background: Muscle fatigue has been reported as a risk factor for the
development of performance-related musculoskeletal disorders (PRMD) in
musicians. However, little research exists to support this claim. The aim of
this study was to investigate whether changes occur in muscle activity
patterns during high string performance over a prolonged playing period, and
whether this is influenced by PRMD.
Methods: High string musicians were divided into a PRMD and a non-PRMD
group. They played a chromatic scale pre and post and a self-chosen “hard”
(Borg scale 16-17) piece of music for one hour. Electromyography data
recorded from arm, shoulder and trunk muscles was analyzed: the amplitude
to measure muscle activity characteristics and the lower frequency to
measure muscle fatigue. Differences between and within groups and the
frequency spectrum were analyzed using linear mixed models.
Results: Fifteen musicians participated (7 PRMD: 22.8 years, 2 male/5 female
and 8 non-PRMD: 34.3 years, 2 male/6 female). Changes in muscle activation
patterns were observed between and within both groups, however changes
varied significantly depending on group affiliation. Significant low frequency
spectrum changes between groups were observed in overall muscles of the
right arm (p=0.04) and left forearm flexors (p=0.05) following one hour of
playing.
Conclusions: Muscle activity and frequency spectrum shifts differ in high
string musicians with and without PRMD, suggesting possible differential
muscle fatigue effects between the groups.
Objectives
To develop a time-efficient motor control (MC) test battery while maximising diagnostic accuracy of both a two-level and three-level classification system for patients with non-specific low back pain (LBP).
Design
Case–control study.
Setting
Four private physiotherapy practices in northern Germany.
Participants
Consecutive males and females presenting to a physiotherapy clinic with non-specific LBP (n=65) were compared with 66 healthy-matched controls.
Primary outcome measures
Accuracy (sensitivity, specificity, Youden index, positive/negative likelihood ratio, area under the curve (AUC)) of a clinically driven consensus-based test battery including the ideal number of test items as well as threshold values and most accurate items.
Results
For both the two and three-level categorisation system, the ideal number of test items was 10. With increasing number of failed tests, the probability of having LBP increases. The overall discrimination potential for the two-level categorisation system of the test is good (AUC=0.85) with an optimal cut-off of three failed tests. The overall discrimination potential of the three-level categorisation system is fair (volume under the surface=0.52). The optimal cut-off for the 10-item test battery for categorisation into none, mild/moderate and severe MC impairment is three and six failed tests, respectively.
Conclusion
A 10-item test battery is recommended for both the two-level (impairment or not) and three-level (none, mild, moderate/severe) categorisation of patients with non-specific LBP.