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Shoulder Muscle Activity of Badminton players in an overhead smash. A comparison before and after fatigue
- 1. Farha Nisha (085563F) Joycelyn Chow (085562A) See Ke Yun (085597E) Koh Hui An (086429X) Quek Yi Hui (085571C) SCHOOL OF HEALTH SCIENCES
- 3. Overhead smash Preparatory Acceleration Follow Through Hurov et al, 2009 Translational and rotational components Creates strong biomechanics forces and ↑ stress Various musculoskeletal pathologies
- 4. Szues et al, 2009
- 9. 8 Subjects (n=8); 5 Females, 3 Males
- 13. Upper Trapezius Infraspinatus Lower Trapezius Serratus Anterior
- 17. Event point Pre- event Post- event Reflective stickers
- 22. Event point Pre- event Post- event
- 24. 1 st shot 2 nd shot 3rd shot 0.05s 0.05s
- 27. Intraclass Correlation Coefficient (ICC) 95% confidence interval Intraclass Correlation N Average Measures 0.843 3
- 28. Wilcoxon Signed Ranks Test Significance p<0.05
- 29. Contact point Infrapsinatus 0.1653s Lower Trapezius 0.1795s Upper Trapezius 0.2007s Serratus Anterior 0.2008s Prefatigue Postfatigue Contact point Upper Trapezius 0.1776s Infrapsinatus 0.1654s Serratus Anterior 0.1606s Lower Trapezius 0.1349s
- 33. Kibler et al 1988 Hurrow J 2009 Works as a force couple to stabalize the scapula Centers the humeral head within the glenoid fossa Moynes et al 1986 Infraspinatus
- 37. Szues et al, 2009
- 42. Question and Answer Session
- 43. Background and aim: Shoulder injuries are most common type of injury during overhead badminton smash. Fatigue of the muscles around the shoulder complex may lead to neuromuscular alterations that predispose to shoulder injuries. This study aim is to find out if there is any change in muscle activation patterns and to compare amount of muscle activity during a badminton smash before and after the fatigue protocol Method: 8 healthy and young subjects meeting our inclusion criteria participated in our study. Surface Electromyographic (EMG) data were collected from serratus anterior, upper trapezius, lower trapezius and infraspinatus. Maximal Voluntary Isometric contraction (MVIC) readings were obtained for every muscle for each subject. Each subject underwent 3 pre-fatigue smashes, a fatigue protocol and 3 post-fatigue smashes. The Root Mean Square (RMS) value of each smash was recorded. All data obtained from the smashes were normalized using the MVIC data obtained earlier. Results: All muscles except lower trapezius have showed statistically significant increase in RMS value, which is a sign of fatigue. (Table 1) In addition, there was a change in muscle recruiment patterns between pre and post fatigue. There was a delay in serratus anterior activation, whereas, infraspinatus and upper trapezius were activated earlier during post fatigue EMG muscle recruitment. (Table 2) Conclusion: In the presence of fatigue, upper trapezius is likely to compensate for other shoulder muscles. Simultaneously, Infraspinatus has to work harder to stabilize the humeral head in the glenoid fossa of the shoulder. Specific endurance training of serratus anterior among badminton players may be beneficial to prevent shoulder pathologies. Rotator cuff muscle endurance training may be beneficial to enhance shoulder stability Diagram 1: Methodology Table 1: Percentage of MVIC pre and post fatigue Table 2: Sequence of muscle activation pre and post fatigue
Editor's Notes
- A good morning to all. Thank you for being present as my group presents to you, our FYP titled shoulder muscle activity of badminton players during the overhead smash, comparing before and after a fatigue task. Our group members are Farha, joycelyn, ke yun, yihui and myself hui an.
- For this presentation, I will be presenting on an introduction to our project, the aims and hypothesis of our study and finally the methodology. While second presenter, Farha will be presenting on the statistical analysis and results of our study, followed by the discussion and will end our presentation with a conclusion
- Prior to our study, we did some research on previous studies and gathered information which was relevant to our project. So, what is known?
- Next, what are the aims and hypothesis of our study?
- Moving on to the methodology of our study.
- Subjects suitable for our study plays competitive or recreational badminton and are aged between 18 to 25. They do not have a history of a severe musculoskeletal injury of the glenohumeral and acromioclavicular joint. So we recruited a total of 8 subjects which matched our study criteria.
- This is the flow of the methods of our study. To begin, here’s what we did for the setting up of our environment
- Our study was conducted in an enclosed room A shuttlecock attached to a string was hung from the ceiling mimicking a shuttlecock being served into the air. The height of the suspended shuttle cock was adjusted according to the subject’s height and how high he or she was able to reach for a smash without jumping A space was cleared for the push up station where the subjects performed the fatigue task. The fatigue protocol will be presented to you in a later part of this presentation.
- Next we attached 2 electrodes to each of the muscle bulk of the muscles selected for this study
- The 4 muscles that we looked at were the UT, SA, LT and INFRA. Referring to - , we’ve attached the electrodes as seen in this photo. Serratus anterior (SA) Place 2 active electrode horizontally (2cm apart) just below the axillary area, at the level of the inferior tip of the scapula and just medial of the latissimus dorsi. Lower Trapezius (LT) Have the patient retract and depress the scapular and then flex the arm to at least 90 degrees. Palpate the inferior medial border of the scapula for the muscle mass that emerges. Place the electrodes on an oblique angle. Upper Trapezius (UT) Place 2 active electrodes (2cm apart) so that they run parallel to the muscle fibers of the upper trapezius, along the ridge of the shoulder, slightly lateral to one half the distance between the cervical spine at C7 and the acromion. Infraspinatus (IS) Palpate the spine of the scapula. 2 closely spaced electrodes (2cm apart) are placed parallel to and approximately 4 cm below the spine of the scapula, on the lateral aspect, over the infrascapular fossa of the scapula.
- Next, we recorded the maximal voluntary isometric contraction on all 4 of the muscles listed previously
- Subjects were instructed to use their best effort in performing the action of the muscle we’re testing on while one tester resisted the motion. And 3 sets of data were obtained per muscle. Data collected during the actual smash shots will be expressed as a % of this Maximal voluntary isometric contraction. And the final data will then be normalized and compared between the subjects
- Next, 3 consecutive shots were taken while the motion analysis system recorded the time frame of the shots. And the EMG system recorded muscle activity
- We were able to identify the event point of the smashes using the motion analysis system as reflective stickers were attached to the shuttlecock and the racket. The event point would be the moment when the racket meets the shuttlecock. The pre event consists of preparatory phase, winding, cocking and acceleration. Event point is the point of contact and the post event is after contact point, follow through and deceleration
- Here’s a short video clip of a subject performing 3 smashes. Subjects performed the 3 smashes at their own pace with no time limit. They were instructed to give their best effort for all 3 shots
- Next, subjects went through a fatigue task
- Which was 2 mins of push ups or to maintain in this push up position, while their feet was place on a 23cm platform. And the borg’s scale was provided to rate the effort required.
- And immediately after the fatigue task
- we recorded the time frame and muscle activity in 3 consecutive post fatigue shots. And finally the time frame of the smashes and muscle activity recorded in pre and post fatigue were matched during Data
- During the study, subjects were instructed to use their maximal effort in all 3 shots before and after the fatigue task. We used the velocity of the smashes to gauge their effort and the results obtained from the % difference in the velocity of the smashes in pre and post fatigue showed that most data points had velocity values with differences from1% to 25%, which is minimal difference. Thus we concluded that max effort was used for shots in pre and post fatigue
- In data analysis, we took 0.05 seconds before and after the contact point according to motion analysis to take into account muscle activity during acceleration and deceleration. Next, the root mean square values were obtained to normalize the data. And now, I will hand over to Farha to continue with the second half of this presentation.
- Inter-rater reliability , which measures homogeneity , is administering the same form to the same people by two or more raters/interviewers so as to establish the extent of consensus on use of the instrument by those who administer it. For continuous data, consensus is measured by intraclass correlation , discussed below. Intraclass correlation (ICC) is used to measure inter-rater reliability for two or more raters when data may be considered interval level. Average measure reliability : the mean of all ratings is the unit of analysis. That is, average measure reliability gives the reliability of the mean of the ratings of all raters. Use this if the research design involves averaging multiple ratings for each item across all raters, perhaps because the researcher judges that using an individual rating would involve too much uncertainty. Interpretation : ICC will be high when any given row tends to have the same score across the columns (which are the raters).
- Asymp Sig (2-tailed)