Full title A study of grip strength among 20-49 year old British adults and comparison to

existing norms

Short Title Grip strength; comparison to existing norms

Full names, institutional addresses and email addresses

Robyn Wozny, Graduate MSc Hand Therapy student, Division of Occupational Therapy and Community

Nursing, Department of Clinical Sciences, College of Health and Life Sciences, Brunel University London,

Uxbridge, UB8 3PH, UK. robyn.wozny@gmail.com

Anna L. Pratt, Division of Occupational Therapy and Community Nursing, Department of Clinical

Sciences, College of Health and Life Sciences, Brunel University London, Uxbridge, UB8 3PH, UK.

Anna.Pratt@brunel.ac.uk

Christine Pereira, Department of Mathematics, College of Engineering, Design and Physical Sciences,

Brunel University London, Uxbridge, UB8 3PH, UK. Christine.Pereira2@brunel.ac.uk

Corresponding author

Anna L. Pratt, Division of Occupational Therapy and Community Nursing, Department of Clinical

Sciences, College of Health and Life Sciences, Brunel University London, Uxbridge, UB8 3PH, UK. 01895

268742. Anna.Pratt@brunel.ac.uk

Full list of declarations

The authors declare that there is no conflict of interest.

Acknowledgements

The authors would like to thank Cathy Ball and Georgia Spiliotopoulou for their critical appraisal on an

earlier version of the manuscript.

1

Abstract

Introduction

Hand grip strength is frequently assessed to evaluate interventions or guide treatment. When using

calibrated equipment in a standardised method hand held dynamometry is a reliable measure for hand

grip strength and can be compared to normative data. However, existing British grip strength normative

data was published 20 years ago.

Methods

A non-experimental quantitative study was carried out to establish if existing UK hand grip norms and

consolidated multinational norms were representative of today’s 20-49 year old British adults

population. The methodology used was modelled on a previous British study using the mean Jamar

dynamometer maximal grip strengths and reported within age bands.

Results

One hundred and thirty-five healthy British citizens of various ethnicities between 20-49 years were

recruited. Grip strength decreased in comparison to the existing British normative data for both males

and females in all age bands. A significant difference exists (p<.05) for male right hand aged 40-44 years

and right and left hands for women 25-29 years and 45-49 years. Significant differences was also noted

in 5 and 8 of the 12 multinational means for men and women respectively.

Discussion

Due to small sample size, the ability of this study to demonstrate a significant difference in mean grip

strength to the earlier British norms is low. However, a small increase in sample size may have resulted

in further significant differences with both studies. Thus, suggesting a larger study taking into

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consideration ethnicity is recommended to ensure valid and reliable grip strength norms are used in

practice.

Keywords grip strength, Jamar, dynamometry, normative data, ethnicity

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Introduction

Hand function and strength are required for dealing with the demands of daily life (1) and Cox et al (2)

report a close relationship (r= -.69, p<0.01) with overall upper extremity function. Therefore, grip

strength measurement is commonly used in hand assessments and as a baseline for developing

treatment goals and evaluating surgical and treatment procedures (3-6). Grip strength measurements

provide practical and viable indications of broader hand function (7) and may be important in predicting

functional ability following injury as hand strength and function have been shown to predict disability

(8). Hand surgeons and therapists alike commonly assess grip strength to establish the functional

integrity of the hand and upper limb (9).

Hand held dynamometry has been repeatedly demonstrated to be a highly reliable measure for hand

grip strength when standardised methods and calibrated equipment are employed (10-14). The current

‘gold standard’ is the Jamar Dynamometer (Jamar, Lafayette Instrument Company, USA), as it has

demonstrated high levels of reliability and validity (15-17) and is affordable for clinical use. This is

despite the Jamar Dynamometer not being the most responsive to change in some client populations

(18). Other more expensive tools, such as the MIE digital grip analyser (MIE Medical Research Ltd, Leeds

UK) demonstrates greater reliability (19). The MIE digital grip analyser reports grip force in Newtons

rather than kgs or lbs meaning difficulties arise when wanting to compare results to previous data. In

addition the Jamar manufacturers suggest that a 5% margin of error is normal and to be expected with

the Jamar dynamometer (17) equating to a +1.5 kg conservative standard error (20) and a correlation

coefficient of +0.9994 which is considered the minimum tolerance level for accurate measurements (21).

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It is therefore not surprising that Jamar dynamometer continues to be used to report hand function (22-

24) and grip strength outcomes of hand rehabilitation and surgery (25-28).

Grip strength can be compared to the contra lateral hand and reported as a percentage (8,26,27). The

effect of the hand dominance on grip strength compared to non-dominant has been reported with some

variation, less than 10% greater (29) and up to 12% greater (30). Sport and leisure pursuits such as

climbing have been found to positively impact on greater grip strength (31) and the non-dominant hand

in professional golfers found to be significantly higher (31). The comparison of the dominant and non-

dominant grip strength is not always possible for bilateral hand injuries or disease, when the grip

strength in both hands may be affected and previous grip strength is unknown for comparative

purposes. Nationally, specific norms are arguably the best evidence to inform clinical practice, and have

been established for numerous countries (32). Similarities and differences in norms have been

attributed to various factors i.e. genetics and anthropometrics, lifestyle and environment, occupational

demand, ethnicity, nutrition and exercise (7,33,34). These factors have been credited with the variation

seen in grip strength both between populations and within populations over time (6,32,35,36). This

suggests that normative data requires periodic revision to stay sufficiently accurate to be useful in the

clinical setting. Furthermore, the literature advocates that normative data has a life span of 15-20 years

(37). At present, British therapists and surgeons are utilising hand grip strength normative data

published twenty years ago which also reports tip, tripod and lateral grip norms (35).

Various studies from different countries have published normative data for grip strength using the Jamar

dynamometer reporting age and gender subgroups (6,29,32,35,36,38-40). A consolidation of Jamar grip

norms to form multinational norms was reported using the results from 12 studies that met the

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inclusion criteria for a meta-analysis (11). This study concludes that these multinational normative

values offer a better comparison than a single study. However, the methodologies vary between the

studies thus Peters et al (39) questioned the proposed normative values reliability. Additionally, in light

of the concerns about the life span of the Gilbertson and Barber-Lomax (35) normative data (used in the

multinational norms) it can be argued that updating of British normative data is a research priority to

maintain confidence in the representativeness and accuracy of the data used in clinical practice.

The normative data for the existing British grip strength (35) was collected from a convenience sample

from urban and rural areas of Cambridge. Questions regarding ethnicity were asked for the first time in

the 1991 UK Census, however as ethnicity of the participants were not reported in the Gilbertson and

Barber-Lomax (35) article it is unknown if the convenience sample was representative of

Cambridgeshire, the UK as a whole in the early 1990’s or in today’s society. In 2001 and 2011

Cambridgeshire had higher proportions of White British residents than England as a whole and a lower

proportion from the majority of ethnic groups (41). Thus it could be suggested that in 1994 a higher

proportion of White British residents and lower proportion of other ethnic groups may have also have

been used in the convenience sample.

In the 1991 census 94.1% of the population categorised themselves as white British and 3.1% Asian in

comparison to 86% and 7.5% of the population in 2011 respectively(42). The other remaining minority

ethnic groups i.e. missed/multi ethnic groups, Asian/Asian British and Black/African/Caribbean/Black

British are also reported to have grown since the 1991 census (42). In Yorkshire (UK), Anjum et al (34)

observed that Asian patients were not able to achieve standard grip strengths. In their study they

compared the hand grip strength of an Asian and European population and concluded that European

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hand grip strength was statistically stronger for both male and female (mean difference = 15.98, p <0.01,

95% CI 9.75-22.20 lbs, and mean difference = 11.65, p <0.01, 95% CI 6.23-17.07 lbs respectively). Over

the last two decades the British population may have undergone significant changes in its ethnic

diversity which may further highlight the need for updated British hand grip strength norms.

The aim of this study was to examine the hand grip strength norms of 20-49 year old adults and to

compare this study’s findings with existing normative data published in 1994

(35), and the multinational normative data (12 studies) published by Bohannan et al (11). The research

hypothesis is that the mean grip strength in this study is significantly different from that published in

1994 (35).

Methods

Ethical approval was obtained from Brunel University London, School of Health Sciences and Social Care

Research Ethics Committee (10/04/HTH/01). All participants give their informed written voluntary

consent to participate in the study. A pilot study with ten participants from various age bands was

carried out to test the recruitment procedure and data collection. This data was included in the final

results as no adjustments were required.

Study design

A non-experimental quantitative inquiry was employed with research design and methodology

replicating Gilbertson and Barber-Lomax’s (35) research. This replication enhanced the comparability

and compatibility to the previously developed British grip strength norms by using e.g. Jamar

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dynomometer, results reported in age bands, measured in kilograms. Protocol deviations arose only

where research demonstrated superior and more rigorous methods for execution e.g. Testing position

demonstrated, standardised verbal instructions and encouragement given, participants blind to the

measurement during testing (9,43,44).

Participants

A cross section of self-described healthy British adults between 20 and 49 years of age were recruited.

Those individuals with a history of upper limb injury within the previous 5 years, upper limb functional

limitations, conditions affecting the upper limb extremity or undergoing treatment for a neck injury

were excluded. The participant’s data was stratified by gender and age consisting of six age categories

of 5-year age intervals, an approach consistent with previous norms development studies (11,32,35,36).

Data collection continued until a minimum of ten participants for each gender/age bands was achieved.

Participants were recruited from shopping centres, high street and a University campus in one London

Borough during a two week period in 2010. This borough contained a diverse range of people,

communities and ethnic minority groups representing a cross section of the British population (42,45).

The multi-site protocol and method of data collection assisted in facilitating the capture of data from a

broad range of ethnic, occupational and socio-economic groups and mirrors the methods used by Wu et

al., (32) in their normative grip strength research. All the participants were asked about their ethnicity

to establish if the cohort was representative of the British population. Table 1 illustrates participant

inclusion and exclusion criteria.

Procedure

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Due to the small margin of error and its affordability in clinical practice, the Jamar Dynamometer was

chosen as the tool to assess grip strength. The same Jamar dynamometer, on the second position, was

utilised throughout the data collection period following calibration verification in accordance with the

method introduced by Fess (46). The Jamar used in this study demonstrated an acceptable <5% error

margin during calibration. A correlation coefficient of +0.9994 is considered the minimum tolerance

level for accurate measurement by Fess (21). This study‘s initial and final instrument calibration yielded

correlation coefficient of 0.9999, thus confirming above adequate Jamar calibration.

A standardised protocol in which the participants sat for the assessment, as recommended by The

American Societies of Hand Therapy (ASHT) (21), was adopted to enhance methodological rigour and

improve reliability (47). This protocol was also used in the 1994 British grip strength norms

development (35), enhancing the comparability of results between the two studies.

The upper limb position and grip required was demonstrated prior to testing to maximise participant

adherence (43). Participants were blind to the measurement during testing to prevent affecting

performance (44). Standardised verbal instructions and encouragement were given in accordance with

Mathiowetz et al., (36) and those employed in grip strength research (9,32,36,43,44,48). The right and

left hands were tested alternately to provide three maximal grip strength recordings for each hand,

beginning with the right hand (35). Each test result was recorded immediately after the event; allowing

a 15 second rest period between tests, negating possible fatigue effects. Grip strength tests were

recorded in kilograms of force.

Data Analysis

9

Descriptive statistics illustrating frequencies, means, standard deviations and ranges of grip strength

provide a concise summary. The data for this study is tabulated separately for males and females, left

and right hands and by age group to enable comparison to identify whether results for grip strength

were similar or different to those obtained by Gilbertson and Barber-Lomax (35) and Bohannon et al.

(11). Reporting data as left and right hands rather than dominant and non-dominant followed the same

format as existing UK norms (35) and multinational norms (11). As there are two different sexes (male

and female), two hands per person (left and right) and six age groups there was a total of 24

independent two-sample t-tests comparing this study with Gilbertson and Barber-Lomax (35) and 24

independent two-sample t-tests comparing this study with Bohannon et al. (11). The assumption of

normality and homogeneity of variance required for a t-test were satisfied for the this study. Results of

Shapiro-Wilk tests conducted suggest it is fair to assume that the distribution of right hand and left hand

grip strength for males and females in each age category, respectively, were sampled from an

approximately normal distribution, at the 1% significance level. In addition, as variances were similar for

corresponding groups, and it is known that the t-test is fairly robust against some heterogeneity of

variance when normality can be assumed, this research has considered homogeneity of variance

between the corresponding groups to be a fair assumption.

In terms of sample size, this study aimed to obtain a similar number of participants within each gender

and age group to Gilbertson and Barber-Lomax (35) who used ten participants within each. Therefore

statistical power was not used to calculate the sample size. Rather, after finding large differences

between the mean grip strength of this study and Gilbertson and Barber-Lomax (35) as well as between

this study and Bohannon et al. (11) we estimated the power of each test ex-post. As the power of many

tests was quite low (less than 0.5) an ex-post sample size calculation was carried out based on a desired

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level of significance. The motivation behind the ex-post investigation of power and sample size is to

determine if there is enough evidence to justify further studies of grip strength due to changing norms.

Results of these investigations are discussed in the following sections.

Results

The sample consisted of 135 healthy British volunteers between 20 and 49 years of age; 65 males

(48.1%) and 70 females (51.9%) from in and around one London Borough.

Demographic data

Participants were from a wide variety of occupational, socio-economic and ethnic backgrounds (Table 1).

The majority of participants (88.9%) were right hand dominant, 8.2% were left hand dominant and the

remaining 3% were ambidextrous (Table 2).

Tables 3a and 3b show the mean grip strength (Kg) and standard deviation of all participants by age

group and hand (right/left) for Gilbertson and Barber-Lomax (35) and this study, for men and women,

respectively. The sample size for each study as well as t-test results (t-statistic, p-value and statistical

power) (Table 3c) are also shown; results significant at <5% (*) and <1% (**) are indicated to the right of

the p-value. The research hypothesis that the mean grip strength estimated in this study is significantly

different from that of the 1994 study was tested using an independent two-sample t-test. The results

suggest that for men aged 40-44yrs, a significant difference exists between right hand grip strengths

(p=0.0245). For women, results suggest that a significant difference in grip strength exists between the

right hand measurements of each study and the left hand measurements of each study for age groups

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25-29yrs (p<0.001 for both hands) and 45-49yrs (p=0.0058 and p=0.0154, respectively). Overall the

results demonstrate that there is now lower grip strength than the existing norms report (35).

A similar comparison between this study and the multinational values of Bohannon et al. (11) (Table 4a,

4b and 4c) suggests that 5 out of 12 mean grip strengths for the men and 8 out of 12 mean grip

strengths for women are significantly different between the existing study and those estimated in the

meta analysis at the 5% level (five of these means are also significantly different at the 1% level).

Discussion

Due to the small sample size in this study the ability of the study to demonstrate a significant difference

in mean grip strength compared with studies of Gilbertson and Barber-Lomax (35) and Bohannon et al.

(11) is quite low for most age groups and hands for both males and females, as shown by a power <0.80

for most tests (Tables 3c and 4c). The power for almost all results that suggest a significant difference

(p<0.05) is above 0.80, which is typically seen as an acceptable minimum while those which were not

statistically significant (p>0.05) had very low power. That is, for these tests the chance of demonstrating

a significant difference, if a difference actually exists was less than 80%. In particular, the statistical

power of non-significant differences between this study and Bohannon et al. (11) ranged from 5% to

71% and between this study and Gilbertson and Barber-Lomax (35) from 5% to 45%. Thus, if a

significant difference does in fact exist, the results for this study do not have a large enough chance of

detecting it. It is therefore suggested that the power of these tests would have been higher with a

larger sample size.

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Observing such low power motivated an ex-post calculation of sample size to determine if a slightly

larger sample may show stronger evidence for significant differences. This revealed that a small

increase in sample size (n=20 for men and n=15 for women) may have resulted in a further six significant

differences (five for men and one for women) with Gilbertson and Barber-Lomax’s (35) findings and a

further four (two each for men and women) when compared with the findings from Bohannon et al.(11);

these specific samples have been indicated by highlighting the sample size with bold font and

superscript ‘a’ (e.g. 10a) in Tables 3a, 3b, 4a and 4b. This is assuming that the overall mean for each age

group and hand stays approximately the same and that the additional participants have a grip strength

within one standard deviation (using the this study’s estimate) of their respective mean. The purpose of

this analysis is not to make more of the results than exists, but to make a case for the need for further

studies of grip strength norms in the UK with increased sample size and statistical power.

It is noted that authors are reporting grip strength norms in different countries (6,29,32,36,38-40)

confirming the importance of relevant data to the particular country. Angst et al (1) reported that mean

grip strength has a north-south gradient with results of men varying from 24.2 kg in Denmark to 14.2 kg

in Calabria (Southern Italy). This reinforces the necessity for each country to have its own norms and

not utilise those derived from multinational norms such as Bohannon et al (11) as supported by data

from this study.

This study has reported the demographics of the participants including ethnicity and as highlighted by

Anjum et al (34) it is important to take it into account. The white ethnic group accounted for majority

(63.7 %) of the participant population and the Asian group (23%) the next largest. This is compared to

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national data of 86% and 7.5% respectively (42). The ethnicity results from this study does not

represent the overall British population (42) however, it is also unlikely that the Gilbertson and Barber-

Lomax (35) study is representative either having identified the population trend for this area (41). The

population for this study were volunteers in a London borough and while it is acknowledged that

London is the most ethnically diverse area (42) normative data should reflect the ethnicity of the whole

population to limit potential ethnicity bias. In addition, in light of these findings the existing tip, tripod

and lateral grip norms (35) may also require investigation.

Conclusion

As previously highlighted, Jamar dynamometry is a highly reliable measure for hand grip when standard

methods and calibrated equipment is utilised (10-14). The verification of the Jamar calibration is

infrequently reported in the literature despite the known inaccuracy levels if not calibrated (21). This

study has been carried out using ASHT standardised grip strength recommendations with the same

calibrated Jamar at the initiation and conclusion of the study, confirming the more than acceptable

margin of error of the instrument. The robust reporting and use of methodology in this study gives

confidence in its methodological reliability (47). This study replicates that of the existing British grip

norms (35) following rigorous methodology and suggests that there is now lower grip strength than the

existing norms report. This may have implications when comparing outcomes of rehabilitation and

surgery or client’s level of disability to the current British grip norms.

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The findings of this study have some limitations in that data collection was carried out in one

geographical area. It is therefore recommended that a larger study encompassing a wider British

geographical area that reflects the ethnicity of the population be carried out to establish a better

representation of normal British population grip strength. The findings from such a study will be

essential for therapists and surgeons when making informed decisions regarding the normality of hand

grip strength in comparison to the population (11).

Acknowledgements

Please see text on title page

Declaration of Conflicting Interests

The authors declare that there is no conflict of interest.

Funding Acknowledgement

This research received no specific grant from ay funding agency in the public, commercial, or not-for-

profit sectors.

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Tables

Table 1. Summary of participant characteristics: Ethnicity.

Ethnicity Frequency (n) Percent %

White 86 63.7

Black 12 8.9

Mixed 4 3.0

Asian 31 23

Other 2 1.5

Total 135 100

20

Table 2. Summary of participant characteristics: Gender and Hand dominance.

Gender Frequency (n) Percent % Right hand

dominant

Left hand

dominant

Ambidextrous

Male 65 48.1 57 6 2

Female 70 51.9 63 5 2

Total 135 100 120 11 4

21

Table 3a. Men’s mean grip strength and Gilbertson and Barber-Lomax (1994) findings.

Age 1994 Results Results from this study

Groups Hand n Mean and SD (Kg) n Mean and SD (Kg)

20-24 R 10 48.15 SD 8.21 14 52.10 SD 6.28

L 10 43.08 SD 8.02 14a 49.76 SD 9.06

25-29 R 10 53.76 SD 9.41 10 a 45.73 SD 10.39

L 10 48.60 SD 10.94 10 45.63 SD 11.31

30-34 R 10 52.63 SD 6.43 11 47.51 SD 9.57

L 10 48.98 SD 7.33 11 a 42.21 SD 9.59

35-39 R 10 53.16 SD 7.61 10 48.43 SD 8.34

L 10 51.75 SD 5.39 10 48.93 SD 10.49

40-44 R 10 55.49 SD 4.65 10 49.47 SD 6.21

L 10 50.40 SD 5.40 10 47.38 SD 7.70

45-49 R 10 49.93 SD 7.44 10 a 43.33 SD 7.70

L 10 48.94 SD 8.38 10 a 41.60 SD 9.01

22

Table 3b. Women’s mean grip strength and Gilbertson and Barber-Lomax (1994) findings.

Age 1994 Results Results from this study

Groups Hand n Mean and SD (Kg) n Mean and SD (Kg)

20-24 R 10 28.33 SD 5.93 12 27.58 SD 5.13

L 10 25.78 SD 5.64 12 26.83 SD 4.02

25-29 R 10 33.82 SD 3.00 11 25.58 SD 3.59

L 10 30.31 SD 2.71 11 22.18 SD 4.54

30-34 R 10 33.97 SD 4.91 10 a 29.63 SD 5.34

L 10 31.64 SD 3.96 10 28.60 SD 5.22

35-39 R 10 32.46 SD 4.38 13 30.49 SD 5.08

L 10 29.77 SD 3.48 13 30.00 SD 5.57

40-44 R 10 30.34 SD 5.41 11 25.88 SD 7.30

L 10 26.23 SD 5.00 11 24.03 SD 7.96

45-49 R 10 35.30 SD 4.88 13 27.67 SD 7.01

L 10 32.06 SD 4.25 13 25.54 SD 7.48

23

24

Table 3c. Men and women’s mean grip strength compared with Gilbertson and Barber-Lomax (1994)

findings.

Age Mens T-Test Results Womens T-Test Results

Groups Hand df t p Power df t p Power

20-24 R 22 1.278 0.2147 0.219 20 -0.314 0.7569 0.059

L 22 1.905 0.0699 0.434 20 0.493 0.6271 0.072

25-29 R 18 -1.811 0.0868 0.388 19 -5.725 <0.0001 ** 0.999

L 18 -0.597 0.5580 0.082 19 -5.034 <0.0001 ** 0.996

30-34 R 19 -1.450 0.1632 0.265 18 -1.892 0.0747 0.419

L 19 -1.827 0.0835 0.397 18 -1.467 0.1596 0.268

35-39 R 18 -1.325 0.2018 0.225 21 -0.997 0.3301 0.149

L 18 -0.756 0.4594 0.103 21 0.121 0.9046 0.051

40-44 R 18 -2.454 0.0245 * 0.636 19 -1.600 0.1261 0.315

L 18 -1.015 0.3233 0.149 19 -0.765 0.4534 0.105

45-49 R 18 -1.949 0.0670 0.441 21 -3.074 0.0058 ** 0.834

25

L 18 -1.886 0.0755 0.417 21 -2.638 0.0154 * 0.709

Key

R Right hand L Left hand

* Results significant at 5% ** Results significant at 1%

a An increase in sample size (n=20 for men and n=15 for women) may have resulted in a

significant difference

26

Table 4a. Men’s mean grip strength and Bohannon et al. (2006) findings.

Age 2006 Results Results from this study

Groups Hand n Mean and SD (Kg) n Mean and SD (Kg)

20-24 R 134 53.30 SD 4.18 14 52.10 SD 6.28

L 134 47.40 SD 4.44 14 49.76 SD 9.06

25-29 R 149 53.90 SD 4.95 10 45.73 SD 10.39

L 149 50.00 SD 4.54 10 45.63 SD 11.31

30-34 R 120 52.80 SD 4.44 11a 47.51 SD 9.57

L 120 49.20 SD 4.49 11 42.21 SD 9.59

35-39 R 117 53.30 SD 4.74 10 a 48.43 SD 8.34

L 117 51.60 SD 3.93 10 48.93 SD 10.49

40-44 R 111 54.10 SD 3.62 10 49.47 SD 6.21

L 111 49.80 SD 3.72 10 47.38 SD 7.70

45-49 R 110 50.40 SD 4.03 10 43.33 SD 7.70

L 110 48.70 SD 4.34 10 41.60 SD 9.01

27

Table 4b. Women’s mean grip strength and Bohannon et al. (2006) findings.

Age 2006 Results Results from this study

Groups Hand n Mean and SD (Kg) n Mean and SD (Kg)

20-24 R 133 30.60 SD 1.94 12 27.58 SD 5.13

L 133 27.90 SD 2.45 12 26.83 SD 4.02

25-29 R 142 33.80 SD 2.19 11 25.58 SD 3.59

L 142 30.80 SD 1.89 11 22.18 SD 4.54

30-34 R 141 33.80 SD 2.50 10 29.63 SD 5.34

L 141 31.80 SD 1.43 10a 28.60 SD 5.22

35-39 R 142 33.20 SD 2.35 13 a 30.49 SD 5.08

L 142 30.20 SD 2.24 13 30.00 SD 5.57

40-44 R 133 32.80 SD 2.45 11 25.88 SD 7.30

L 133 29.30 SD 2.45 11 24.03 SD 7.96

45-49 R 133 33.90 SD 2.60 13 27.67 SD 7.01

L 133 30.80 SD 2.55 13 25.54 SD 7.48

28

Table 4c. Men and women’s mean grip strength compared with Bohannon et al. (2006) findings.

Age Men’s T-Test Results Women’s T-Test Results

Groups Hand df t p Powerdf t p

Powe

r

20-24 R 146 -0.699 0.4857 0.106 143 -2.026 0.0446 * 0.520

L 146 0.963 0.3373 0.158 143 -0.907 0.3659 0.146

25-29 R 157 -2.468 0.0147 * 0.689 151 -7.487 <0.0001 ** 0.999

L 157 -1.215 0.2261 0.225 151 -6.255 <0.0001 ** 0.999

30-34 R 129 -1.816 0.0718 0.435 149 -2.450 0.0154 * 0.682

L 129 -2.394 0.0181 * 0.661 149 -1.933 0.0551 0.483

35-39 R 125 -1.822 0.0709 0.438 153 -1.905 0.0587 0.472

L 125 -0.800 0.4252 0.123 153 -0.129 0.8979 0.052

40-44 R 119 -2.322 0.0219 * 0.634 142 -3.129 0.0021 ** 0.875

L 119 -0.984 0.3273 0.162 142 -2.187 0.0304 * 0.583

45-49 R 118 -2.868 0.0049 ** 0.812 144 -3.183 0.0018 ** 0.885

29

L 118 -2.466 0.0151 * 0.686 144 -2.521 0.0128 * 0.707

Key

R Right hand L Left hand

* Results significant at 5% ** Results significant at 1%

a An increase in sample size (n=20 for men and n=15 for women) may have resulted in a

significant difference

30