Ergonomics

The rail of this study is to investigate the i any(prenominal)trical line potency or MVC ( supreme conscious contraction) by step rod captivate effectuality, girdle energy, oarlock ability, automobile trunk military unit and key squash military group. So that separately participants force out percentile set in the state for distributively vividness category earth-closet be take cared and human biomechanical capabilities and sex act variability in human capabilities understructure be understood by comparison the info compile. as well as the effects of the factors, standardized make out span, carpus simulate or utilise the controlling placement, on to each one of the saturation categories freighter be examined. . excogitation Isometric power is the force that a heft host drop utilize without movement. Maximum Isometric intensiveness is the level best force that a muscle group bathroom exert without movement. It is as well as called M VC (maximum voluntary contraction). Some of the widely utilise isometric bearings atomic human body 18 arm intensiveness, shoulder strong suit, complex (leg) loudness, plunk for ( physical structure) strength, handbag strength and pinch strength. All of the strength categories argon metrical for the nationals excluding for the atomic number 53s having health problems just intimately their waist.These standards ar with by utilize Caldwell Protocol, which regularises that after a build-up time of about 2 seconds, the subject is required to maintain a soaked state maximal action for at least 3 seconds and this (average) level is interpreted as the subjects strength score. So that we keister severalize that, in general, the isometric strength measurement single-valued bunk requires individuals to build-up their muscular motion slowly everyplace a 4-6 seconds period, without jerking, and maintain the peak exertion for about 3 seconds. This peak exertion (3 sec average) is the isometric strength of the individual.No away motivation should be provided. A light upon of at least 30 seconds should be provided amidst successive exertions if altogether a few measurements atomic number 18 to be made. It is required to increase the rest duration to 2 minutes if about 15 measurements argon to be made in unrivalled attempt session. This additional rest is obligatory to recover from fatigue generated due to the isometric exertion (Mital and Kumar, 1998). spot measuring the strength categories, the effects of some factors like cubital joint angle, articulatio radiocarpea vex, intrigue span and development dominant or non-dominant side argon observed.The orientation of the arm influences human isometric strength exertion capability. As the arm orientation changes the mechanical advantage also changes, go outing in weaker or stronger strength exertions. similarly the wrist orientation is critical in generating isometric torques with n on-powered evanesce tools. Approximately 70% to a greater extent torque is exerted when wrenches ar in the horizontal position than when they argon in vertical positions (Mital and Kumar, 1998). Therefore, by victimization some statistical techniques like analysis of variance (Analysis of pas seul), the substance of the factors that are mentioned before is tested. . OBJECTIVES The main bearing of this study is to investigate the isometric strength or MVC (maximum voluntary contraction) by measuring clasp strength, arm strength, leg strength, torso strength and key pinch strength. So that each participants strength percentile value in the population for each strength category jakes be calculated and human biomechanical capabilities and congenator variability in human capabilities back tooth be understood by dopevas the schooling collected.Also the effects of the factors, like bobby pin span, wrist armorial bearing or victimisation the dominant side, on each of the st rength categories can be examined. 4. METHODS The experimental line of take shape consisted of performing isometric wait, pinch seize and upseting contractions for the combinations of the levels of wrist posture, enamour-span and by using the dominant or non-dominant side in a standing posture. The equipments apply are handgrip dynamometer, pinch grip dynamometer and lift platform.Our lab group conducting this study consists of both female and a male student, which are all remedy-handed and served as subjects. musical composition measuring the grip strength the combinations of objective wrist posture with the 5 grip-span places, deepen from 33mm to 85mm, are used. For the second mise en scene the combinations with the wrist flexion and wrist extension are measured too. then non-dominant side MVC in neutral posture in third setting for males and in second setting for females, and dominant side MVC keeping the wrist in neutral posture and the human articulatio cubiti joint at 150o angle are measured.The solid ground for using the 3rd setting for males and second setting for females is that, on average, 3rd setting is the standard for male hand size, and 2nd setting is the standard for female hand size. After finishing the grip strength measurements, the key pinch strength at neutral arm and wrist posture is measured. After all, by using the lifting platform, MVC for arm, leg and torso strength are measured. While measuring all types of strength categories Caldwell protocol is used and all of the measurements are through with(p) as two exertions. The data including only the maximum recordings can be seen from the hold over below defer 4. Collected data for All Group subdivisions for All military group Categories Name sovereign get by Non-dominant Dominant Arm Strength(MVC) GS (MVC) side GS at parent elbow 150 Female 16. 43 4. 47 19. 6 17 male 37. 86 6. 69 44. 81 19 The maintaining disconcert combines the data collect ed from the subjects with the data taken from the population. By feel at it, one can severalize that for males, with complaisance to grip strength, our ingest guess, 37. 86 is about the 25% tile in strength, which means, Gurkan has to a greater extent(prenominal) strength than about 25% of the population. And by using the corresponding way, we can say that our female subjects devote more strength than 2% of the population on average.And the information like percentiles for the rest of strength categories can be seen in a same manner from the table below. circuit card 5. 2 The percentiles of dainty group and data comparison with the population pic A nonher predate from the study is the descent mingled with grip strength and grip-span and wrist/elbow posture. In order to understand the effects, Analysis of Variance (analysis of variance) test is done. Our analysis of variance surmise is as the spare-time activity H0The group means are non distinct. H1The group means are different. For the ANOVA results we can look at the following table to investigate he r-squared values, p-values and f values to understand the effects and bloods. According to the results taken the highest p-valued factor is the wrist posture which has 3 levels of extension, neutral and flexion. Then issue forths the elbow posture and finally the grip-span. Table 5. 3 R-squared, p-value and f values of factors effecting grip strength r-squared p-value f grip grip span 0. 9395 0. 64 3. 45 strength vs. wrist posture 0. 8997 0. 769 0. 28 elbow posture 0. 9896 0. 321 1. 71 The quality of the move is attached by the statistical number r-squared. An r-squared of 1. 0 would mean that the model prospect the data perfectly, with the line going right through every data point. to a greater extent existentistically, with real data youd get an r-squared of or so 0. 85. Finally in order to entertain the other techniques we exhaust looked at the result of the Tukey s test. 5. DISCUSSION The implication of strength measurements in Ergonomic Intervention and the uses and immensity of strength data in ergonomic intervention can be explained by the means of the following concepts.Many industrial activities are performed through human intervention. It is generally sure that knowledge of what a person can or can non do under qualify circumstances is essential for efficient work role and injury prevention. Human strength recommendations for tool programme and work and workspace design impart also been receiving considerable attention. deficiency of design guidelines and screening procedures can lead to overloading of the muscle-tendon bone-joint system and, thereby, fatigue and possible outcome injuries. As a matter of fact, Chaffin et al. (1978) have reported that the incidence rate of back injuries ustained on the line of work increased when the job strength requirements exceeded isometric strengths of the workers. Human strengths of indiv iduals gum olibanum form the basis for many design data bases and screening procedures. Therefore we can say that the overall intent of these developments is to recoil injuries and, in the process, maximize industrial productivity. 6. CONCLUSIONS AND RECOMMENDATIONS The results assure that although theres not a important difference, the optimum grip-span setting for the males is the 3rd, for the females is the 2nd setting as its been told in the literature.These findings were supported by the results of tukeys test, which shows that the maximum strength is achieved with these settings. Also when we look at the R-squared values from the ANOVA test apply to understand the relationship between grip strength and grip-span and wrist/elbow posture, we can see that the effect is not so significant because of the large R-squared values. But if we indirect request to sort them, wrist posture is the near significant, and then grip-span and elbow posture come respectively, where it can be seen easily from the table below Table 7. R-squared values for the factors effecting grip strenth r-squared grip grip span 0. 9395 strength vs. wrist posture 0. 8997 elbow posture 0. 9896 Although the effect is not significant, the study suggests that grip span of a tool and the posture of wrist and elbow are principal(prenominal) factors to be considered.From this study it can be understood that the isometric strength measurement is inexpensive and flexible. But the major single out of isometric testing is that only one joint angle is tested at a time. If different joint angles choose to be tested, the process must be repeated for each angle. Therefore as a further study, ways to test different joint angles one at a time can be studied. REFERENCES Eksioglu, M. , 2006. Optimal work-rest cycles for an isometric intermittent seize task as a function of force, posture and grip span.Ergonomics, 49, 180-201. Eksioglu, M. , 2004. Relative optimum grip span as a func tion of hand anthropometry. external diary of industrial Ergonomics, 34, 1-12. Mital, A. , Kumar, S. , 1998. Human muscle strength definitions, measurement, and usage Part I Guidelines for the practitioner. International Journal of Industrial Ergonomics, 22, 101-121. Mital, A. , Kumar, S. , 1998. Human muscle strength definitions, measurement, and usage Part II The scientific basis (knowledge base) for the guide.International Journal of Industrial Ergonomics, 22, 123-144. http//en. wikipedia. org/wiki/Confidence_ legal separation http//talkstats. com/showthread. php? t=2460 http//en. wikipedia. org/wiki/Analysis_of_variance http//en. wikipedia. org/wiki/Students_t-test http//en. wikipedia. org/wiki/Multiple_comparisons http//www. le. ac. uk/bl/gat/virtualfc/Stats/mult. htm APPENDIX A) descriptive statistics of the collected ideal data (mean, std. dev. , and throw away only). In calculations, we have considered only the highest values but not all trial values. Table A. descripti ve Statistics of the collected sample data Descriptive Statistics pistillate variable star suppose StDev Variance Range FEMALE 16,43 4,47 19,96 17,0 Descriptive Statistics MALE versatile signify StDev Variance Range MALE 37,86 6,69 44,81 19,00 B) to each one participants strength percentile values in the population for each strength category (pinch strength calculations excluded). Again, we have considered only the highest values but not all trial values. Table B. 1 Grip strength percentile calculations Descriptive Statistics Dicle Duygu Gurkan Variable Q1 Median Q3 IQR Dicle 10,00 15,00 17,00 7,00 Duygu 15,00 19,00 20,00 5,00 Gurkan 33,00 36,00 43,00 10,00 Table B. 2 Leg, arm, torso strength percentiles measured for each participant Descriptive Statistics ARM. M LEG. F LEG. M TORSO. M TORSO. FARM. DYG ARM. DCL Variable Q1 Median Q3 IQR ARM.M * 34,300 * * LEG. F * 48,40 * * LEG. M * 109,90 * * TORSO. M * 119,1 * * TORSO. F * 53,00 * * ARM.DYG * 15 ,650 * * ARM. DCL * 11,20 * * C) 95% faith interval for the true average grip strength, establish on the sample data. pic C. I. for alpha = 0. 05 For males (30. 334 , 45. 386) For females (9. 466 , 23. 394) These intervals say that in 95 of 100 trials these intervals ensure the true average grip strength. D) Grip-strength vs. grip-width and wrist/elbow posture relationships Table D. 1 ANOVA Grip-span sets relationship General linear Model Value versus Grip genus Phallus Factor fictitious character Levels Values Grip firm 5 set1 set2 set3 set4 set5 Member rigid 3 dicle duygu gurkan Analysis of Variance for Value, using Adjusted SS for Tests Source DF Seq SS Adj SS Adj MS F P Grip 4 171,60 171,60 42,90 3,45 0,064 Member 2 1374,40 1374,40 687,20 55,20 0,000 Error 8 99,60 99,60 12,45 marrow 14 1645,60 S = 3,52846 R-Sq = 93,95% R-Sq(adj) = 89,41% Table D. 2 ANOVA Wrist posture relationship General Linear Model values versus position label Factor Typ e Levels Values position dictated 3 ext flex neutral names fixed 3 dicle duygu gurkan Analysis of Variance for values, using Adjusted SS for Tests Source DF Seq SS Adj SS Adj MS F P position 2 18,67 18,67 9,33 0,28 0,769 names 2 1178,00 1178,00 589,00 17,67 0,010 Error 4 133,33 133,33 33,33 conglomeration 8 1330,00 S = 5,77350 R-Sq = 89,97% R-Sq(adj) = 79,95% Table D. 3 ANOVA Elbow position relationship General Linear Model rime versus elbow. members Factor Type Levels Values elbow. p fixed 2 ds150 neutral members fixed 3 dicle duygu gurkan Analysis of Variance for numbers, using Adjusted SS for Tests Source DF Seq SS Adj SS Adj MS F P elbow. p 1 6,00 6,00 6,00 1,71 0,321 members 2 660,33 660,33 330,17 94,33 0,010 Error 2 7,00 7,00 3,50 Total 5 673,33 S = 1,87083 R-Sq = 98,96% R-Sq(adj) = 97,40% The quality of the fit is given by the statistical number r-squared. An r-squared of 1. 0 would mean that the model fit the data perfectly, with the line going right through every data point. More realistically, with real data youd get an r-squared of around 0. 85. So that, we can say that the effect of the factors investigated is not significant by face at the large R-squared values. E) analogy analysis among the data collected (Analysis of Variance, multiple comparison and t-tests, as necessary). In testing the null supposal that the population mean is equal to a specified value? 0, one uses the statistic pic wheresis thesample standard deviationof the sample andnis the sample size.The degrees of freedom used in this test isn? 1. Also we can use the Multiple proportion Tests, which are a group of tests that follow on from one or two-factor ANOVA or the Kruskal-Wallis test,but only if significant differences have been found. It would appear that they could be used on their own but because they are not as powerful as ANOVA or Kruskal-Wallis, they can occasionally fail to find differences when the former succeed. They a re used for exactly the same reasons that ANOVA and Kruskal-Wallis are used, but provide more information. ANOVA and Kruskal-Wallis can only tell you whether there is a difference between two or more of your groups and not which ones.We made ANOVA test for the grip-span settings, elbow/wrist posture and dominant/non-dominant side usage. When we look at the R-squared values from the ANOVA results, we fail to wipe out the null hypothesis H0 The group means are not different. H1 The group means are different. Because, we have large R-squared values. And also by looking at the F and p-values,which is a small value, we can say that there is not a significant difference between the test groups. There is no compulsion to conduct Tukey test because of failing to reject the null hypothesis, but despite of this internet site we have conducted to support our previous results. And once again we saw that there is not a significant difference. C25 = set1 subtracted from C25 debase Center velocity -++++ set2 -27,59 5,00 37,59 (*) set3 -26,26 6,33 38,93 (-*) set4 -32,59 0,00 32,59 (*) set5 -35,26 -2,67 29,93 (*) -++++ -25 0 25 50 In this test, set 1 is compared with the other sets average. And as it can be seen the sets are not significantly different, there is only a slight difference, because the range includes 0. So that theres chance that different sets give the same results. TUKEYS analyse FOR SETS One-way ANOVA C26 versus C25 Source DF SS MS F P C25 4 172 43 0,29 0,877 Error 10 1474 147 Total 14 1646 S = 12,14 R-Sq = 10,43% R-Sq(adj) = 0,00% Individual 95% CIs For Mean Based on Pooled StDev Level N Mean StDev -++++ set1 3 21,67 12,42 (*) set2 3 26,67 14,15 (*) set3 3 28,00 13,75 (*) set4 3 21,67 10,60 (*) set5 3 19,00 9,00 (*) -++++ 12 24 36 48 Pooled StDev = 12,14 Tukey 95% concurrent Confidence Intervals All Pairwise Comparisons among Levels of C25 Individual confidence level = 99,18% C25 = set1 subtracted from C25 get off Center focal ratio -++++ set2 -27,59 5,00 37,59 (*) set3 -26,26 6,33 38,93 (-*) set4 -32,59 0,00 32,59 (*) set5 -35,26 -2,67 29,93 (*) -++++ -25 0 25 50 C25 = set2 subtracted from C25 Lower Center pep pill -++++ set3 -31,26 1,33 33,93 (-*) set4 -37,59 -5,00 27,59 (*) set5 -40,26 -7,67 24,93 (*) -++++ -25 0 25 50 C25 = set3 subtracted from C25 Lower Center Upper -++++ set4 -38,93 -6,33 26,26 (*-) set5 -41,59 -9,00 23,59 (*) -++++ -25 0 25 50 C25 = set4 subtracted from C25 Lower Center Upper -++++ set5 -35,26 -2,67 29,93 (*) -++++ -25 0 25 50 E) CONTINUED Comparison of our data with population data. In order to compare, we should calculate the percentiles Calculating percentiles for a value comparative to a population with known mean (50th %tile) and standard deviation (assuming normal distribution) 1. propose z. pic z = (37,86 40. 5)/3. 84 = -0,69 2. Look up the z value from the table of additive probabilities of the s tandard normal distribution. z = -0,69 is about 0. 25 so the percentile is 25% for the first calculation.Here is the table of our all computations taken from EXCEL Table E. 1 Comparison of our data with population data pic The following table combines the data collected from the subjects with the data taken from the population. By looking at it, one can say that for males, with respect to grip strength, our sample mean, 37. 86 is about the 25% tile in strength, which means, Gurkan has more strength than about 25% of the population. And by using the same way, we can say that our female subjects have more strength than 2% of the population on average. And the information like percentiles for the rest of strength categories can be seen in a same manner from the table above.