1. International conference – Women’s health and work March 4-6 2015, Brussels Physical Strength: Results and Differences in Age and Gender Patrick Serafin, André Klußmann, Christoph Mühlemeyer, Inna Levchuk, Karl-Heinz Lang, Hansjürgen Gebhardt Institute of occupational Health, Safety and Ergonomics e.V. – ASER, Wuppertal

2. Background Objective: support ergonomic product and workplace design –in manufacturing of work equipment, tools (e.g. tools such as pliers, screwdrivers, etc); –in manufacturing of products from the private sector (e.g. appliances such as can openers, etc) –in ergonomic job and task analysis Challenge: demographic change –larger proportion of older people in the total population; –larger proportion of older workers at the workplaces. 2

3. Background 3 Trend behavior of the maximum static muscle strength in male and female persons in the course of life (according to Hollmann and Hettinger, 2000) 010203040506070 20 40 60 80 100 0 average maximum force (%) age in years males females Sample: Population? Employees? Number of participants? Which method for force estimation? How many Newtons are 100 %? Which force cases were estimated? … standard deviation, confidence interval …

4. Aims and Methods Aims –Population sample on hand dimensions and different cases of maximum force Methods –Standardized force measurements (in standing positions) pulling gripping turning (screwdriver) –Determination of hand sizes 3-D hand-scanner templates, etc. –Standardized questionnaire - personal data age, gender, body height / weight sports, leisure time activities occupational activities and physical exposures musculoskeletal symptoms and disorders 4

5. Methods: Standardized force measurements Height-adjustable test stand to equalize individual variations of anthropometric dimensions 5

6. Methods: Standardized force measurements Measurement of pulling strength 6

7. Methods: Standardized force measurements Measurement of grip strength 7

8. Methods: Standardized force measurements Measurement of torque strength 8 left hand right hand

9. Body posture during force measurement 9 pulling strengthgrip strengthtorque strength

10. 10 Methods of force estimation square method increasing force to a maximum within 1 second and holding maximal force over a predetermined period of time (usually 2-6 seconds) ramp method increasing force smoothly and stadily to a maximum over a predetermined period of time (usually 4-5 seconds) 10 (Rühmann & Schmidtke, 1992) (Rohmert et al., 1992)

11. Sample: n=1,207; including 428 females and 779 males 11

12. Results: pulling strength 12

13. Results: grip strength 13

14. Results: torque strength 14

15. Strength ratio of women and men 15 0.66 0.62 0.55

16. Summary / Discussion Ratio of maximum force between men and women F / M varies from 0.55 to 0.66 The level of maximum force only slightly differs among participants in the age from 15 to 69 years In the age groups between 20 and 59 years (nearly) no significant differences in the level of force can be seen These results are not in accordance with most data from literature, like e.g. from Hollmann & Hettinger (2000). In this publication (among others), the 20 to 25 years old males were described as strongest, with permanent significantly decreasing force with increasing age. 16

17. Limiations Cross-sectional study Individual force progress during life can not be deduced Statements about (sub-)maximum forces with frequent execution can not be derived Statements about dexterity and endurance can not be derived –possibly here: major differences in the age groups 17

18. Outlook Preliminary, descriptive analyzes show no significant differences between physically active and inactive people –Further analysis on this topic are required Correlations between hand dimensions and force could give more useful information for ergonomic design of products. –Further analysis on this topic are required Outlook: Multivariate analyzes including –Sports, leisure activities, MSDs –Relationships between the types of force. Target: Implementation of data in planning programs of product developers. 18

19. Thank you for your attention Patrick Serafin Institute ASER e.V. Corneliusstr. 31, 42329 Wuppertal Germany Email: serafin@institut-aser.de 19