Objectives

1. procedures and important factors in measuring strength
2. the effect of posture on strength
3. the effect of personal factors such as gender on strength
4. the application of strength data and strength percentile calculations

Procedures

1. Conduct a survey of grip and pinch strength.
   • adjust the grip dynamometer so that the thumb and index finger overlap
   • zero the grip dynamometer
   • perform a maximal exertion while counting slowly to 5 (5s)
   • do not:
     • jerk
     • press against external objects
   • repeat using the thumb and first two fingers with the pinch dynamometer:
   • the pinch dynamometer is not adjustable
   • record: sex, age and weight

   (a s)	(b)

2. Calculate 5%tiles and 95%tiles for each parameter
   • males
   • females
   • pooled

3. Calculate the lower 5% and upper 95% of limits for each parameter. You can do this graphically, from the means and standard deviations (assuming a normal or log normal distribution); or calculate it using a spread sheet function.

4. Is hand strength related to age?
   • Yes, but it is hard to see this from your data because age only ranged from 20 to 32 years. Recall that age actually increase somewhat in this range. Remember it is hard to find a relationship between two ariables if you don't have much variablity in your dependent variable.

5. Is hand strength related to weight? Why?
   • Yes, You can see this in your scatter plot and from your regression and correlation coefficients. There are two important factors contributing to this relationship.
     • First, gender and age are related. On the average females have a smaller body mass than males. The average female mass for this class was 59.6Kg versus 85.5 for the males.
     • Second, heavier people must exert more force to support their body weight than lighter people. This contributes to strength conditioning.

6. Are pinch and grip strength related? Why?
   • Yes, You can see this in your scatter plot and from your regression and correlation coefficients. Both exertions involve many of the same muscles and similar mechanical parameters.

7. Calculate:
   1. a 5% female grip strength
   2. Discuss possible applications for these data?

   ---

   Sample Data:

   Sex	Age	Wt-Kg	Grip-Kg	Pinch-Kg
   0	26	70	41	5.5
   0	23	42	33	2.6
   0	23	61	30	1.2
   0	26	73	40	3.2
   0	32	64	32	2.0
   0	20	52	33	1.7
   0	20	59	34	2.3
   0	21	50	31	1.5
   0	21	64	37	2.2
   0	22	61	43	2.2
   0	21	59	33	2.2
   0	21	59	28	1.2
   1	22	118	55	6.0
   1	25	82	58	3.6
   1	23	91	51	7.2
   1	23	80	55	5.5
   1	23	80	63	9.4
   1	25	91	50	6.6
   1	29	81	65	8.0
   1	22	77	44	4.8
   1	23	80	40	3.1
   1	29	77	63	4.3
   1	27	77	51	4.5
   1	26	77	45	4.5
   1	23	86	45	4.5
   1	22	84	58	4.8
   1	23	109	52	5.6
   1	21	61	51	4.5
   1	21	91	46	6.2
   1	21	95	41	8.2

   Female

   Min	20	42	28	1.2
   Max	32	73	43	5.5
   Avg	23.0	59.6	34.6	2.3
   Stdev	3.5	8.4	4.7	1.2
   5%	20.0	46.5	29.1	1.2
   95%	28.7	71.5	41.9	4.2

   Male

   Min	21	61	40	3.1
   Max	29	118	65	9.4
   Avg	23.8	85.5	51.8	5.6
   Stdev	2.5	12.8	7.6	1.7
   5%	21.0	74.9	40.9	3.5
   95%	29.0	110.5	63.3	8.4

   Pooled

   Min	20	42	28	1.2
   Max	32	118	65	9.4
   Avg	23.5	75.1	44.9	4.3
   Stdev	2.9	17.0	10.8	2.2
   5%	20.5	51.0	30.5	1.3
   95%	29.0	103.0	63.0	8.1

   Plot: Hand Strength versus Age

   Plot: Hand Strength versus Weight

   Plot: Pinch Strength versus Grip Strength