4. RESULTS
4.4 VOLITIONAL MOVEMENTS OUT OF SYNERGIES: SHOULDER ABDUCTION
4.4.1 INERTIAL INDICATORS MOVEMENT OUT OF SYNERGIES
The eight subjects were instructed to perform the movement three times, so that the peak values of the joint angles can be recorded and averaged over the three trials. The maximum of the absolute values regarding shoulder abduction, elbow flexion and forearm pronation along with corresponding standard deviation are presented in Figure 4.4.2. The results concerning the Wilcoxon signed rank test are shown in Table 4.4.1. According to the results, there is a significant difference between the median pairs regarding the pathologically unaffected and affected shoulder abduction, elbow flexion and forearm pronation/supination.
Figure 4.4.1: Joint angles of the first subject during the first trial regarding the 90° shoulder abduction with the elbow at 0° and the forearm pronated (left). Then performed pathologically affected (right).
44 Figure 4.4.2: Joint angles averaged over the three trials presented with corresponding standard deviation. Subjects
performed shoulder abduction first pathologically unaffected and then with mimicked pathological synergies.
Table 4.4.1: Results of the Wilcoxon signed rank test. The joint angles of interest are shoulder abduction (SA), elbow flexion (EF), and forearm pronation or supination (FPS). The data is presented as the median and corresponding interquartile range (IQR). The IQR can be used to divide the corresponding data set into quartiles or to construct a box plot. The last column listed the p-values of the test based on a 5% significance level. Values except the p-values are expressed in degrees.
Kinematics Unaffected Median (deg) [IQR] (deg)
Affected
Median (deg) [IQR] (deg)
Difference
Median (deg) [IQR] (deg) P SA 91 [87,103] 70 [68,78] 20 [7,25] 0.025 EF 9 [7,24] 51 [24,76] -38 [-57,-12] 0.012 FPS 21 [15,38] 27 [21,42] -4 [-8,0] 0.036
4.4.2 MEAN SRE AND MUSCLE ACTIVITY
The mean value of each envelope is determined and is used as an indicator of the level of activity of each muscle during the movement. Activity of the FCR and ECR can be excluded for further analysis since wrist flexion and wrist extension are not assessed by the FMA-UE during shoulder abduction. The averaged muscle activities with corresponding standard deviations during the three trials performed by each subject are presented in Figure 4.4.3.
The Wilcoxon signed rank test is used to investigate whether the median difference in muscle activity between the pathologically unaffected and pathologically affected shoulder flexion is zero. The results of the statistical test can be seen in Table 4.4.2. According to the results, muscle activity regarding the biceps brachii, the triceps lateral head and long head, the deltoideus medial, and the deltoideus anterior
45 decreased significantly when the subjects performed shoulder abduction with pathologically affected synergies (𝑝 = 0.012).
Figure 4.4.3: Muscle activity averaged over the three pathologically unaffected trials (left) and affected trials (right). The averaged muscle activity of the biceps, lateral head triceps, long head triceps, deltoideus medial and deltoideus anterior respectively for all subjects is of interest.
Table 4.4.2: Results of the Wilcoxon signed rank test. The data is presented as the median and corresponding interquartile range (IQR). The IQR can be used to divide the corresponding data set into quartiles or to construct a box plot. Muscles of interest are biceps, lateral head triceps, long head triceps, deltoideus medial and deltoideus anterior respectively. The last column listed the p-values of the test based on a 5% significance level. Values except the p- values are expressed in millivolts.
Muscle activity Unaffected Median (mV) [IQR] (mV) Affected Median (mV) [IQR] (mV) Difference Median (mV) [IQR] (mV) P Bi 0.02 [0.02,0.03] 0.01 [0.00,0.02] 0.01 [0.00,0.01] 0.012 Tri (lat) 0.05 [0.05,0.07] 0.02 [0.02,0.03] 0.02 [0.02,0.04] 0.012 Tri (long) 0.02 [0.02,0.04] 0.01 [0.01,0.01] 0.01 [0.01,0.02] 0.012 DM 0.07 [0.05,0.10] 0.04 [0.03,0.05] 0.03 [0.02,0.04] 0.012 DA 0.09 [0.08,0.11] 0.04 [0.03,0.05] 0.04 [0.03,0.06] 0.012
4.4.3 SYNERGISTIC AND COACTIVATION SRE PATTERNS
The synergistic coactivation patterns of the subjects regarding the pathologically unaffected and affected shoulder abduction is presented in Appendix D. In case stroke survivors cannot overcome the influence of the flexor synergy during shoulder abduction, the elbow cannot be kept fully extended and the elbow tends to flex as a result of the strong linkage between the elbow flexors and the shoulder abduction muscles
46 (Brunnstrom, 1970). According to Brunnstrom, stroke patients can execute shoulder abduction with the elbow fully extended successfully when elbow extension and forearm pronation associate with shoulder girdle retraction and shoulder abduction. Therefore, the search for linkages between the shoulder abductors, elbow flexors, and elbow extensors are of interest. In order to investigate whether elbow flexion and shoulder abduction are associated, the cross-correlations and corresponding time lags between the biceps brachii and the deltoideus medial are determined. Moreover, in order to investigate whether elbow extension and shoulder abduction are associated, the cross-correlations and corresponding time lags between the triceps lateral head and deltoideus medial is determined as well as the cross-correlations and corresponding time lags between the triceps long head and the deltoideus medial (see Appendix D).
The Wilcoxon signed rank test is used to investigate whether the pathologically unaffected shoulder abductions differ significantly from the affected shoulder abductions performed by the subjects. In this case, the cross-correlations and corresponding time lags between the biceps brachii, deltoideus medial triceps lateral head, and triceps long head during the pathologically unaffected and affected shoulder flexions are investigated and shown in Table 4.4.3. According to the results, a significant difference in cross-correlations and corresponding time lags between the biceps and the deltoideus medial, and between the triceps long head and deltoideus medial could not be detected (p-values greater than or equal to 0.05). Regarding the cross-correlations between the triceps lateral head and the deltoideus medial, a significant difference could be detected (𝑝 = 0.036). However, a significant difference in corresponding time lags regarding the latter muscle pair could not be detected.
Table 4.4.3: Results of the Wilcoxon signed rank test. The data is presented as the median and corresponding interquartile range (IQR) regarding the cross-correlation coefficient and corresponding time lag. The IQR can be used to divide the corresponding data set into quartiles or to construct a box plot. The muscle pair of interest are the biceps and the deltoideus medial, the triceps lateral head and the deltoideus medial, and the triceps long head and the deltoideus medial. The last column listed the p-values of the test based on a 5% significance level. The time lags are expressed in seconds. Unaffected Median [IQR] Affected Median [IQR] Difference Median [IQR] P 𝑅Bi−DM 0.91 [0.64,0.94] 0.84 [0.78,0.89] 0.02 [-0.14,0.11] 0.674 𝑅Tri(lat)−DM 0.94 [0.83,0.95] 0.86 [0.77,0.88] 0.06 [0.03,0.10] 0.036 𝑅Tri(long)−DM 0.91 [0.70,0.94] 0.69 [0.50,0.89] 0.12 [-0.03,0.39] 0.161 𝜏Bi−DM (s) 0.02 [0.00,0.17] 0.02s [0.01,0.03] -0.00 [-0.02,0.14] 0.735 𝜏Tri(lat)−DM (s) 0.01 [0.00,0.11] 0.06s [0.00,0.28] -0.00 [-0.06,0.06] 0.889 𝜏Tri(long)−DM (s) -0.01 [-0.05,0.03] 0.00s [0.00,0.21] -0.00 [-0.05,0.03] 0.726
47