CHAPTER FIVE RESULTS
5.2 KEY PINCH STRENGTH
A Gaussian distribution of key pinch strength tests was confirmed before analysis of the data, Figure 9 a, b.
Influence of Gender-Key pinch strength on the right and left hand are statistically significantly higher in men than in women (p=0.000, p=0.000) with a mean of 8.3kg on the right and 7.6kg on the left hand in men and a mean of 6.3kg on the right hand and 5.8kg on the left hand in women. The strength of the left hand averages 92% of the right hand in both men and women, table 11, figure 10 and 11.
Influence of Handedness
The right key pinch strength is higher for the right hand dominant male than his left hand dominant counterpart (p=0.57), similarly, the left key pinch strength is higher for the left hand dominant male than his right hand dominant counterpart, (p=0.7). However for the females, the right key pinch strength is higher for the left hand dominant than the right hand dominant female, (p=0.009). The left key pinch strength is also higher for the left hand dominant female than the right hand dominant female, (p=0.004), table 12.
47 Influence of Age
Figure 12 shows that the key pinch strength varies with age. The greatest strength is seen in the 40-49 year age group in both males and females.
Influence of Anthropometric measures
There was no correlation between the weight, height and body mass index and the left and right key pinch strength tests in the male participants. There was a positive correlation between the right key pinch strength and the right hand span but this was not seen on the left. In the female participants the height correlated with the right and left key pinch strengths. The right and left hand spans also showed a positive correlation with the key pinch on the right and left hands, table 13.
A summary of the normal values obtained in this study for key pinch strength in both sexes is presented in tables14 and 15. All participants demonstrated adequacy in the activities of daily living however 16.1% (n=39) participants had had previous hand injuries, figure 14. Six (2.5%) participants had had previous hand surgeries, figure 15.
No scar was seen on the hand in 84.7% (n=205) of the participants, figure 16. There was no correlation between the occurrence of a previous hand injury, surgery and the presence of a scar on the hand grip or key pinch strength tests, table 16.
TWO- POINT DISCRIMINATION DISTANCE
Summaries of the two-point discrimination of all the ten digits of the participants are as shown in table 17. Approximately ninety nine percent (98.8%) of the participants had a two-point discrimination distance of less than 5mm
48
Tables
Table 1: Age distribution of the 242 participants stratified by sex
Age groups Male Female Total
20-29 30-39 40-49 50-59 60-69 70-79
>80
48(29.4%) 68(41.7%) 29(17.8%) 11(6.7%) 5(3.1%) 1(0.6%) 1(0.6)
21(26.6%) 20(25.3%) 22(27.8%) 12(15.2%) 3(3.8%) -
-
69(28.5%) 88(36.4%) 51(21.1%) 23(9.5%) 8(3.3%) 2(0.8%) 1(0.4%)
Total 163 79 242
49 Table 2: Hand dominance of the participants
Hand dominance Male Female Total
Right Left Missing
139(85.3%) 23(14.1%) 1
70(88.5%) 8(10.1%) 1
209(86.4%) 31(12.4%) 2(0.8%)
Total 163 79 242
50
Table 3: Independent sample t test comparison of right and left hand grip strengths between males and females.
Hand Sex Mean handgrip
strength (kg)
SD p
Right
Left
Male(n=163) Female(n=79) Male (n=163) Female(n=79)
32.07 20.25 30.70 18.7
7.6 5.3 7.7 5.3
0.000
0.000
51
Table 4: Independent samples t test comparison of right and left hand grip strength based on hand dominance
Hand dominance
Measured Grip Mean (kg) SD p
Right
Left
Right (n=209) Left (n=209) Right (n=31) Left (n=31)
28.23 26.33 28.28 30.03
8.86 8.74 8.58 9.91
0.00
0.00
52
Table 5: Independent sample t test comparison of right and left hand grip strength between right and left hand dominant participants
Handgrip Hand dominance
Mean SD p
Right
Left
Right (n=209) Left (n=31) Right (n=209) Left (n=31)
28.2 28.3 26.3 30.0
8.9 8.6 8.7 9.9
0.98
0.031
53
Table 6: Handgrip strength stratified by sex and hand dominance
Sex Measured
side
Hand dominance
Mean SD p
Males Right
Left
Right Left Right Left
32.09 31.71 30.14 33.88
7.78 6.40 7.71 7.26
0.83
0.03
Females Right
Left
Right Left Right Left
20.60 18.42 18.76 18.97
5.16 6.09 4.90 8.14
0.27
0.91
54
Table 7: Pearson’s correlation between grip strength and constitutional variables
Variable Male Female
Weight Height
Body Mass Index Hand span
Right Left .173 .111 .125 .127 .109 .045 .073 .112
Right Left .359** .385**
.286* .306**
.252* .263* .061 .112
**Correlation is significant at 0.01 level
*Correlation is significant at 0.05 level
55
Table 8: Summary of normal values for male grip strength obtained in this study
Right grip strength (kg) Left grip strength (kg)
Age (yrs)
Mean SD Min Max Mean SD Min Max
20-29 30-39 40-49
> 50
33 33 31 27
7 8 7 8
19 17 17 8
53 49 43 38
31 32 30 26
7 8 8 8
17 16 16 10
46 46 41 37
56
Table 9: Summary of normal values for female grip strength obtained in this study
Right grip strength (kg) Left grip strength (kg)
Age (yrs)
Mean SD Min Max Mean SD Min Max
20-29 30-39 40-49
>50
20 21 20 20
5 6 5 6
12 11 10 10
30 33 30 34
19 19 18 19
5 6 4 7
9 8 8 10
29 32 25 38
57
Table 10: Comparison of age at which peak mean handgrip strength was obtained between this study and other studies
Population Women Age
(yrs)
Men Age
(yrs) DGrip
strength (kg)
NDGrip strength (kg)
DGrip strength (kg)
NDGrip strength (kg)
Nigerian27 25.1 23.0 20-29 36.3 32.2 20-29
Swiss28 34.0 34.7 40-44 55.9 53.4 35-39
German26 33 32 30-39 54 52 30-39
Asian30 19 17 25-34 31 28 25-34
UK70 28.5 26.6 35-44 48.6 44.8 35-44
This study 21 19 30-39 33 32 30-39
D-Dominant, ND-Non-dominant
58
Table 11: Independent sample t test comparison of right and left hand key pinch strengths between males and females.
Hand Sex Mean key pinch
strength (kg)
SD p
Right
Left
Male(n=163) Female(n=79) Male (n=163) Female(n=79)
8.27 6.26 7.58 5.78
2.7 1.5 2.5 1.5
0.000
0.000
59
Table 12: Influence of side and hand dominance on key pinch strength.
Gender Key pinch Hand dominance
n Mean key
pinch strength (kg)
SD p
Male
Female
Right
Left
Right
Left
R L R L R L R L
139 23 139 23 70 8 68 8
8.3 7.9 7.5 7.7 6.2 7.6 5.7 7.2
2.7 1.8 2.5 2.3 1.4 1.4 1.3 2.0
0.57
0.7
0.009
0.004
60
Table 13: Correlation between key pinch strength and constitutional variables
Variable Male Female
Weight Height
Body Mass Index Hand span
Right Left .122 .073 .073 .026 .080 .056 .201* .132
Right Left .093 .163 .349** .270* -.082 .040 .437** .303**
**Correlation is significant at 0.01 level
*Correlation is significant at 0.05 level
61
Table 14: Normal values for male key pinch strength obtained in this study
Right pinch strength (kg) Left pinch strength(kg) Age
(yrs)
Mean SD Min Max Mean SD Min Max
20-29 30-39 40-49
>50
8 9 9 7
2 3 3 3
2 3 2 4
16 16 13 14
7 8 8 7
2 3 3 3
2 3 2 2
12 15 14 14
62
Table 15: Normal values for female key pinch strength obtained in this study
Right key pinch strength (kg) Left key pinch strength (kg) Age
(yrs)
Mean SD Min Max Mean SD Min Max
20-29 30-39 40-49
>50
6 6 6 7
1 1 1 2
4 4 4 3
7 9 8 13
6 6 6 6
2 1 1 2
3 3 3 3
12 8 8 12
63
Table 16: Correlation between grip and pinch strengths and hand injury, hand surgery and presence of scar
Variable Hand Grip Key Pinch
Hand injury Hand surgery Presence of Scar
Right Left -.038 -.027 -.008 -.032 -.030 -.030
Right Left -.074 -.036 -.035 .043 -.075 .034
64
Table 17: Two-point discrimination distance of participants
Right hand digits
<5mm % 6-15mm % >15mm
Thumb Index Middle Ring Little
239 239 239 238 239
98.8 98.8 98.8 98.3 98.8
3 3 3 4 3
1.2 1.2 1.2 1.7 1.2
- - - - -
Left hand digits
Thumb Index Middle Ring Little
239 239 239 239 238
98.8 98.8 98.8 98.8 98.3
3 3 3 3 4
1.2 1.2 1.2 1.2 1.7
- - - - -
65
Figures
a. b.
c. d.
Figure 4 a-d Gaussian distribution of hand grip strength, weight and height
66
e. f.
g.
Figure 4 e-g Gaussian distribution of body mass index and hand span
67
Figure 5: Box plot showing gender related mean right handgrip strength (kg)
68
Figure 6: Boxplot showing gender related mean left handgrip strength (kg)
69
Figure 7: Mean right handgrip strength plotted against age group in males and females
70
Figure 8: Mean left handgrip strength plotted against age group in males and female
71 a
b
Figure 9a, b: Gaussian distribution of right and left mean key pinch strengths
72
Figure 10: Box plot showing mean right pinch strengths in males and females
73
Figure 11: Box plot showing mean left pinch strengths in males and females
74
Figure 12: Box plot showing right mean key pinch strength plotted against age group in males and females
75
Figure 13: Box plot showing left mean key pinch strength plotted against age group in males and females
76
Figure 14: Frequency of occurrence of hand injuries among participants
77
Figure 15: Frequency of occurrence of hand surgeries among participants
78
Figure 16: Pie chart showing the frequency of presence of scar on the hand of participants
79