Grip strength,functional range and anthropometric dimensions,and indication on fulfilling occupations in the home and workplace: A cross-sectional study

Abstract

Introduction

Little is known about the relationship between the types of grip strength, functional range, anthropometric measures, and function in the home and workplace. The study aimed to determine their relationships and explore their contributions to performing usual work duties and overall function in participants with and without hand and wrist injury.

Method

Forty-four participants were measured on Maximal Voluntary Isometric Grip Strength, Rapid Exchange Grip Contractions and Isometric Endurance, Forearm Length and Volumetry, and the Dart Thrower’s Motion (DTM) measure. They completed the Patient Rated Wrist and Hand Evaluation and the Disabilities of the Arm, Shoulder and Hand Work Module.

Results

The grip measures significantly correlated with Volumetry (r = 0.62–0.74) in participants with and without hand and wrist injury. The Isometric Endurance and DTM measure of the non-injured hand were found to be contributing factors for participants with hand and wrist injury when returning to usual work duties and overall function.

Conclusion

The non-injured hand function plays a role in the overall function for participants with hand and wrist injuries. Isometric Endurance and DTM measure could assist clinicians in determining suitable rehabilitation targets, resulting in a better function required for occupations in the home or workplace.

Keywords

Grip strength anthropometric measures functional ranges daily occupation hand and wrist injury

Introduction

Upper limb injuries account for between 30% and 40% of work-related injuries and are a continuing problem within the Australian workforce (Driscoll et al., 2008). When an individual has recovered from their upper limb injury, grip strength testing is one of the major assessments to indicate the function and fulfilling occupations in the home and workplace (Kunelius et al., 2007). For example, grip strength that excludes personal factors was found to be correlated with the Disabilities of the Arm, Shoulder and Hand (DASH) (Beumer and Lindau, 2014). Grip strength is an essential part of performing numerous daily tasks, and upper extremity injuries affecting grip strength can hinder one’s participation in activities (Farzad et al., 2015). Besides daily tasks, grip strength is relied on by many occupations such as manual industrial laborers and assembly line workers (Nicolay and Walker, 2005). Grip strength has been used to indicate function (e.g., Celis-Morales et al., 2018).

Grip strength is commonly measured using a Jamar Dynamometer (e.g., Bellace et al., 2000). The Maximal Voluntary Isometric Grip Strength is the most commonly reported measure (Gerodimos et al., 2017; Lagerström and Nordgren, 1996). This is tested by instructing the individual to squeeze the dynamometer at 100% effort, holding the grip for no longer than 2 seconds (Nicolay and Walker, 2005). However, it has been questioned if this is the most appropriate measure as it is relatively rare to encounter situations within the home and workplace that require this type of maximal exertion compared to tasks that require continual static holding or repeated dynamic gripping (Nicolay and Walker, 2005). Isometric Endurance and Rapid Exchange Grip Contractions are two common measures to assess one’s continual static holding or repeated dynamic gripping. Isometric Endurance is tested by instructing the individual to squeeze and hold the dynamometer using full effort for 30 s (Nicolay and Walker, 2005). This is used to determine the maximal static grip of a person. Rapid Exchange Grip Contractions are also used to determine a person’s maximal static grip and has been commonly used as an assessment to determine submaximal grip effort (Joughin et al., 1993; Shechtman and Taylor, 2000). An individual will alternate the dynamometer between the left and right hands as rapidly as possible for between five and 10 maximal effort grips (Ashton and Myers, 2004).

To determine one’s grip strength, an individual’s hand and forearm’s anthropometric dimensions are hypothesized to be important factors. Previous studies have reported a correlation between grip strength and either hand length or width (Abaraogu et al., 2017; Kunelius et al., 2007; Shurrab et al., 2015). Another possible measure would be the length of the forearm from elbow to fingertip. Volumetry is another possible anthropometric factor when determining one’s grip strength (Farrell et al., 2003).

Besides grip strength, one’s hand and wrist range of motion in a functional plan is also essential for fulfilling occupations in home and workplace. The Dart-Throwing Motion (DTM) has been suggested to be functionally important as it follows the natural pattern of wrist movement in daily activities (Bugden, 2013). The goniometric assessment of the DTM is tested to be a reliable and valid assessment of measuring the impact that injury to one’s upper limb function (intraclass correlation coefficients = 0.70–0.83 and 0.91–0.92 for inter-rater and test–retest reliability, respectively; Pearson correlation coefficients between the DTM and wrist active range of motion assessment = 0.45–0.73, and with the Patient Rated Wrist and Hand Evaluation (PRWHE) 0.36–0.53) (Parish et al., 2018).

Purpose of the Study

It is currently unknown if grip strength and the type of grip strength measure relate to the anthropometric measures. Therefore, the study aimed to determine relationships between the measures of grip strength and the anthropometric dimensions in both participants with and without hand and wrist injury. The second aim was to explore the contributions of grip strength measures, anthropometric measures, and ranges of motion to performance of usual work duties and overall function in right-handed people with and without hand and wrist injury. The third aim was to explore the same in people with hand and wrist injury.

Method

Design

This was a cross-sectional study, approved by the South Eastern Sydney Local Health District Human Research Ethics Committee.

Participants

Two groups of individuals were recruited for this study, those with and without hand and wrist injury. Using the first aim of the study, a total of 42 participants were recruited, with power set at 0.95, an alpha value of 0.05, and an expected correlation of variables of 0.50, using a correlation bivariate normal model. Group 1 included individuals who had sustained an injury to the hand, wrist and forearm and were in recovery between 6 weeks and 3 months after the injury. They had no medical restrictions on gripping and were able to perform pain-free grip. Group 2 included individuals who had no previous hand and wrist injury that required treatment. Participants were aged 18–65 years. The exclusion criteria included any illness in the last 7 days and chronic injuries or neurological conditions that affect upper limb function.

Procedures

All the data collection sessions were conducted at the Hand Therapy Unit in Sydney Hospital. Participants for Group 2 without hand and wrist injury were identified and recruited by convenience sampling. They were the accompanying friends or family of patients in the Hand Therapy Unit. Participants for Group 1 with hand and wrist injury were identified and screened by the investigators or therapists in the Hand Therapy Unit according to the selection criteria. Participants gave their written informed consent before data collection was started. Preceding the 20-min assessment session, participants’ sociodemographic data such as age, gender, hand dominance, education, current occupation, and years in the occupation were collected by clinical personnel who were independent of this research. Participants in Group 1 were further asked on their hand and wrist injury, date of injury, if they had returned to work or usual work duties and when they returned to work or usual work duties. The participants were then assessed on the three grip strength measures, the anthropometric dimensions, and ranges of motion of the DTM measure by one investigator (EH) as described below. Participants also completed two patient-rated questionnaires including the PRWHE (MacDermid et al., 2007) and the Disabilities of the Arm, Shoulder and Hand Work Module (DASH-W) (Beaton et al., 2001; Institute for Work and Health, 2006).

In completing the three grip strength assessments, participants were provided with a minimum two-minute break between each of the grip strength measures, allowing them to rest and prevent fatigue (Bellace et al., 2000). On average, participants took between two to 5 minutes in the break between grip strength measures.

Grip strength measures

All grip strength measures were taken by an electronic Jamar® Smart Hand Dynamometer (handle position three), connected to the Jamar dynamometer application on an iPad device. There were three types of grip strength measures: 1) the Maximal Voluntary Isometric Grip Strength, 2) the Rapid Exchange Grip Contractions, and 3) the Isometric Endurance. With the Maximal Voluntary Isometric Grip Strength, the participant was asked to use a 100% effort to squeeze the dynamometer and hold the grip for 2 s (Nicolay and Walker, 2005). The single measurement of effort was recorded to prevent fatigue among participants (Coldham et al., 2006). For the Rapid Exchange Grip Contractions, the participant was asked to remain in the same hand and body position as the maximal voluntary isometric grip assessment while the dynamometer is alternated between both the left and right hand as rapidly as possible for five maximal effort grips (Ashton and Myers, 2004). The average of five efforts was taken (Hamilton et al., 1994). To measure the Isometric Endurance, the participant was instructed to squeeze and hold the dynamometer utilizing the same position as the maximal voluntary isometric grip assessment using full effort for 30 s, allowing the measurement of the participant’s endurance during a constant hold (Nicolay and Walker, 2005). The maximum grip strength was recorded for the Isometric Endurance.

Measures

Anthropometric measures

Two measures were taken, the Forearm Length and Volumetry.

For the Forearm Length, the participant was measured from the tip of the middle finger to their olecranon process using a soft tape measure.

For the Volumetry, the participant was asked to lower their hand and forearm into a water-filled container (a volumeter) to a standard distance. The amount of water displaced in milliliters was collected (Maihafer et al., 2003).

Functional ranges through the Dart Thrower’s Motion (DTM) measure

The participant was asked to grasp a hammer with their fingers and thumb with the handle grasped across their distal palmar crease and performed ulnar flexion and radial extension of the DTM. The participants’ ranges of motion were measured using a 15 cm goniometer (Bugden, 2013; Parish et al., 2018).

Fulfilling occupations and performance of usual work duties

The PRWHE is a patient-reported questionnaire on wrist and hand function with two subscales, the first which assesses the participant’s pain in the hand and wrist joint through a 10-point Likert scale (0 = none, 10 = worst), and the second assessing their functional difficulties in activities of daily living on a 10-point Likert scale (0 = no difficulty, 10 = unable to do). The scores range from 0 to 100, with higher scores indicating more pain and functional difficulties (MacDermid et al., 2007).

For performance of usual work duties, the DASH-W was adopted. It is a self-reported questionnaire, which measures the impact of the upper limb injury an individual experience on their work performance. The responses for the Work module are scaled on a 5-point Likert scale (1 = no difficulty, 2 = mild difficulty, 3 = moderate difficulty, 4 = severe difficulty, 5 = unable). The scores range from 0 to 100, with higher scores indicating more activity limitations (Beaton et al., 2001; Institute for Work and Health, 2006).

Statistical analysis

All statistical analyses were done using SPSS, version 25.

To answer the first aim, Pearson’s correlation was used to assess the relationships between the grip strength measures and the anthropometric measures in the right and left hand, respectively, in both participants with and without hand and wrist injury. A P value of <0.004, adjusted with Bonferroni correction, was considered statistically significant for the analyses.

For the second and third aims, stepwise linear regression analyses were used, with the DASH-W indicating performance of usual work duties and the PRWHE representing overall function. The absence of multicollinearity was checked using VIF values. A VIF value below 10 indicates that the assumption is met. For the second aim that involved all right-hand dominant participants, all the measures of both the right and the left arms were put as variables. For the third aim which included only participants with hand and wrist injury, the measures of the injured and non-injured sides were put as the variables. A P value of <0.05 was considered statistically significant for the linear regression analyses.

Results

In total, 44 participants agreed to participate in the study, with two out of the 44 participants' data being excluded due to equipment error and not fitting the selection criteria. Table 1 showed the participants characteristics.

Table 1.

Characteristics of participants with (n = 21) and without upper limb injury (n = 21).

Characteristics	Upper limb injury	No upper limb injury	P value
Age (y), mean (SD)	40.9 (14.52)	36.7 (11.91)	0.319
Gender, women, n (%)	9 (42.9)	18 (85.7)	0.003*
Right-handed, n (%)	20 (95.2)	18 (85.7)	0.306
Education, n (%)
Did not complete school certificate	–	1 (4.8)	0.055
School certificate	3 (14.3)	3 (14.3)
High school	4 (19)	6 (28.6)
Tafe	3 (14.3)	9 (42.9)
University	11 (52.4)	2 (9.5)
Current occupation, n (%)
Student	1 (4.8)	6 (28.6)	0.047*
Blue collar	7 (33.3)	5 (23.8)
White collar	10 (47.6)	10 (47.6)
Retired	3 (14.3)	–
Years in the occupation, mean (SD)	9.19 (8.89)	8.81 (11.14)	0.903
Injury, fracture, n (%)	12 (57.1)
Multiple	6 (28.6)
Tendon/ligament	2 (9.6)
Laceration	1 (4.8)
Injury side—right, n (%)	13 (61.9)
Injury location, n (%)
Carpals	6 (28.6)
Metacarpals	4 (19)
Thumb/fingers	11 (52.4)
Weeks since injury mean (SD)	8.81 (1.77)
Return to work/usual duties, n (%)
Full duties/modified duties	17 (95.2)
Has not returned to work	1 (4.8)

SD = standard deviation.

P ≤ 0.05.

Participants without hand and wrist injury had significantly better performance in the DTM, PRWHE, and DASH-W measures (Table 2).

Table 2.

Comparison of all measures taken between participants with (n = 21) and without upper limb injury (n =21).

Assessment	Upper limb injuries, mean (SD.)	No upper limb injury, mean (SD.)	P value	95% CI (all participants)	Eta squared
Maximal Voluntary Isometric Grip Strength (kg) (right)	34.47 (15.11)	29.31 (8.95)	0.37	27.98–35.80
Maximal Voluntary Isometric Grip Strength (kg) (left)	35.35 (13.51)	28.65 (8.15)	0.09	28.41–35.59
Rapid Exchange Grip Contraction (kg) (right)	30.77 (13.07)	22.87 (6.05)	0.03*	23.44–30.19	0.95
Rapid Exchange Grip Contraction (kg) (left)	31.42 (12.55)	23.38 (6.76)	0.03*	24.05–30.75	0.95
Isometric Endurance (kg) (right)	27.46 (12.41)	21.18 (8.51)	0.11	20.89–27.74
Isometric Endurance (kg) (left)	29.49 (11.36)	21.49 (8.72)	0.03*	22.13–28.85	0.95
Forearm Length (cm) (right) #	46.21 (2.86)	44.61 (2.45)	0.06	44.55–46.27
Forearm Length (cm) (left) #	46.11 (2.88)	44.42 (2.24)	0.04*	44.43–46.11	0.39
Volumetry (mL) (right) #	494.29 (86.63)	429.38 (90.07)	0.02*	432.77–490.89	0.93
Volumetry (mL) (left)	476.10 (80.20)	418.76 (88.14)	0.03*	419.96–474.90	0.91
DTM radial extension (°) (right) #	52.72 (10.73)	52.00 (10.73)	0.83	49.05–55.67	0.73
DTM ulnar flexion (°) (right) #	11.70 (2.08)	15.77 (2.82)	<0.001**	12.74–14.74	0.74
DTM radial extension (°) (left)	51.27 (8.87)	52.18 (8.55)	0.79	49.04–54.41
DTM ulnar flexion (°) (left)	11.42 (1.57)	14.76 (3.14)	0.001**	12.16–14.02	0.52
PRWHE (0–100)	20.81 (14.76)	7.07 (15.14)	<0.001**	8.85–19.03	0.83
DASH-W (0–100)	22.32 (17.74)	6.84 (10.80)	0.001**	9.44–19.72	0.33

SD = standard deviation; DTM = Dart Thrower’s Motion; 95% CI = 95% confidence interval.

P ≤ 0.05,

P ≤ 0.001. P values are a result of a Mann–Whitney U test (except # = independent sample t test).

Relationship between grip strength measure and anthropometric measures

Participants with hand and wrist injury

All three grip strength measures on the right hand significantly correlated with most Forearm Length and Volumetry, except the Maximal Voluntary Isometric Grip Strength of the right hand and the Isometric Endurance of the right hand with right Volumetry (Table 3). Slightly higher correlations were found between the Forearm Length and the Maximal Voluntary Isometric Grip Strength of both hands, the Rapid Exchange Grip Contraction of both hands, and the Isometric Endurance of the right hand. Similar strength of correlations was found between the Isometric Endurance of the left hand and the two anthropometric measures.

Table 3.

Pearson correlation between grip strength measures and anthropometric measures.

Anthropometric measures	MVIG (kg) (right)	MVIG (kg) (left)	RE (kg) (right)	RE (kg) (left)	IE (kg) (right)	IE (kg) (left)
Participants with upper limb injury (n = 21)
Forearm Length (cm) (right)	0.750*	—	0.753*	—	0.708*	—
Forearm Length (cm) (left)	—	0.740*	—	0.707*	—	0.600*
Volumetry (mL) (right)	0.53	—	0.625*	—	0.49	—
Volumetry (mL) (left)	—	0.688*	—	0.632*	—	0.616*
Participants without upper limb injury (n = 21)
Forearm Length (cm) (right)	0.661*	—	0.57	—	0.48	—
Forearm Length (cm) (left)	—	0.56	—	0.46	—	0.39
Volumetry (mL) (right)	0.623*	—	0.740*	—	0.715*	—
Volumetry (mL) (left)	—	0.54	—	0.674*	—	0.657*

SD = standard deviation; MVIG = Maximal Voluntary Isometric Grip Strength; RE = Rapid Exchange Grip Contraction; IE = Isometric Endurance.

Correlation is significant at less than 0.004 level (2-tailed).

Participants without hand and wrist injury

Correlations of grip strength measures with Volumetry were mostly significant (Table 3). Only the right Forearm Length and the Maximal Voluntary Isometric Grip Strength of the right hand was significantly correlated.

Variables associated with performance of usual work duties and occupations

The assumption to perform linear regression analysis was met for both analyses. The VIF values ranged between 1.05 and 2.46 in the DASH-W analysis and 1.03 in the PRWHE analysis. The Isometric Endurance of the left hand and the right hand, the Forearm Length of the right hand, and the DTM ulnar flexion of the right hand were associated with the DASH-W score (R ² = 0.59) (Table 4). For the PRWHE, the Volumetry and the DTM radial extension of the right hand were shown to be the contributing variables (R ² = 0.26) (Table 5).

Table 4.

Results of stepwise linear regression analysis to predict the contributions of the measures to performance of usual work duties (DASH-W) in right-hand dominant participants with and without upper limb injuries (n = 38).

Model summary	R ²	Adjusted R ²	Standard error
	0.59	0.54	11.64
Coefficients	Beta	Significance	95% CI
Constant	−67.76	0.09	−146.82, 11.29
Isometric Endurance on the left hand	1.17	<0.001	0.62, 1.71
Isometric Endurance on the right hand	−0.99	0.001	−1.56, −0.42
DTM ulnar flexion on the right hand	−1.81	0.007	−3.09, −0.53
Forearm Length on the right hand	2.21	0.03	0.28, 4.15

95% CI = 95% confidence interval; $R^{2}$ = explained variance by the regression model.

Table 5.

Results of stepwise linear regression analysis to predict the contributions of the measures to overall function (PRWHE) in right-hand dominant participants with and without upper limb injuries (n = 38).

Model summary	R ²	Adjusted R ²	Standard error
	0.26	0.22	13.50
Coefficients	Beta	Significance	95% CI
ConstantVolumetry on the right handDTM radial extension on the right hand	4.39	0.76	−24.81, 33.59
	0.07	0.004	0.02, 0.12
	−0.46	0.04	−0.89, −0.02

95% CI = 95% confidence interval; $R^{2}$ = explained variance by the regression.

Variables associated with performance of usual work duties and occupations in participants with hand and wrist injury

The assumption to perform linear regression analysis was also met for both analyses. The VIF values were 1.00 in the DASH-W analysis and ranged from 1 to 1.03 in the PRWHE analysis. The result found that only Isometric Endurance on the participants’ non-injured side was associated with the DASH-W (R ² = 0.20) (Table 6). The DTM radial extension on the participants’ non-injured side was associated with the PRWHE (R ² = 0.19) (Table 7).

Table 6.

Results of stepwise linear regression analysis to predict the contributions of the measures of grip strength, anthropometric dimensions and functional ranges to performance of usual work duties (DASH-W) in participants with upper limb injuries (n = 21).

Model summary	R ²	Adjusted R ²	Standard error
	0.20	0.16	16.28
Coefficients	Beta	Significance	95% CI
ConstantIsometric Endurance on the non-injured side	2.83	0.77	−17.29, 22.95
ConstantIsometric Endurance on the non-injured side	0.61	0.04	0.03, 1.19

95% CI = 95% confidence interval; $R^{2}$ = explained variance by the regression model.

Table 7.

Results of stepwise linear regression analysis to predict the contributions of the measures of grip strength, anthropometric dimensions and functional ranges to overall function (PRWHE) in participants with upper limb injuries (n = 21).

Model summary	R ²	Adjusted R ²	Standard error
	0.19	0.15	13.60
Coefficients	Beta	Significance	95% CI
ConstantDTM radial extension on the non-injured side	60.12	0.004	21.18, 99.07
ConstantDTM radial extension on the non-injured side	−0.76	0.05	−1.49 to −0.02

95% CI = 95% confidence interval; $R^{2}$ = explained variance by the regression model.

Discussion and implications

Our study results revealed significant correlations between almost all three of the grip strength measures and the Forearm Length and Volumetry across participants without injury as they have not experienced possible muscle atrophy or edema in the limb. Correlations of anthropometric measures such as body weight and height, and body mass index with grip strength have been reported (Klum et al., 2012). Our results are also supported by Abaraogu et al. (2017) that found middle finger length correlated with grip strength as the middle finger is generally the longest. The length of one’s fingers could assist with the mechanical advantage of the hand when undertaking grasping tasks in everyday life. The results of our study could indicate that the Forearm Length would assist with the mechanical advantage during the hand gripping tasks. We postulate that this could serve more on the mechanical advantage than only the middle finger length. However, Fallahi and Jadidian (2011) did not find any correlation between the two. It remains questionable whether the relationship between Forearm Length and grip strength is a function of the tool that is used to assess grip strength. It may be more ergonomically suited for participants with a certain upper limb size than others. In the participant group with hand and wrist injury, the grip strength measures were significantly correlated with the Volumetry. Forearm circumference as indicated by Volumetry, rather than Forearm Length, is better predictor of wrist torque and muscle activation (Chimera et al., 2021).

When determining the contributions of the measures of grip strength, anthropometric dimensions, and functional ranges to performance of usual work duties in all participants who were right-hand dominant, it was found that Isometric Endurance on both the left and right hand, ulnar flexion measure of the DTM measure on the right hand and Forearm Length on the right hand were found as contributing factors to the outcome of the DASH-W, and the radial extension measure of the DTM measure and Volumetry of the right hand being the contributing factors of the PRWHE. This finding provides general information on the contributions of the measures on ones’ overall function required for their occupations. It could provide clinicians with insights regarding the hand measures that they could work on with people after a hand injury. As this analysis only included the right-hand dominant (38 out of 42), all of the right hand measures could be explained in part as a result of hand dominance. The Isometric Endurance on the left hand may have been a contributing factor as most every day or work tasks require both hands, rarely at home or in the workplace is an individual only using their dominant hand. We postulate that the ulnar flexion of the DTM measure on the dominant hand was included in this model as the ulnar side of the hand acts as a stabilizer of the hand, assisting with the function of the hand (Iida et al., 2012). The Isometric Endurance measure could have been the only grip strength measure contributing to this model. This concurs with our postulation that Isometric Endurance may be considered a more functional measure. Participants more commonly use a sustained grip in daily tasks rather than the quick grip strength measures recorded from the Maximal Voluntary Isometric Grip Strength and Rapid Exchange Grip Contractions. Nicolay and Walker (2005) supported the idea that Maximal Voluntary Isometric Grip Strength may not be the most appropriate measure, as generally, one may undertake tasks that require either continual static holding or repeated dynamic gripping. The results also appear to concur with Vollert et al. (2018); Westbrook et al. (2002) that Rapid Exchange Grip cannot reliably detect voluntary effort. Despite these postulations, we acknowledge that this study concurred with previous studies (e.g., Coenen et al., 2013) and showed a relative lack of relationship between the self-reported and impairment measures.

In participants with hand and wrist injury, the Isometric Endurance on the non-injured side was found to contribute to the outcome of the DASH-W. Participants' injured side generally showed a lower grip strength due to injury. Therefore, the non-injured side could have been used as compensation while undertaking usual work duties or while at work. It could have also contributed to the outcome of the DASH-W as the questions in this measure can be interpreted as based on an individual’s strength when completing the tasks at work. The Isometric Endurance measure on the non-injured side would be the only contributing grip strength measure due to participants using this type of grip in daily occupations rather than Maximal Voluntary Isometric Grip Strength and Rapid Exchange Grip Contractions. However, in previous studies, Maximal Voluntary Isometric Grip Strength has been commonly reported as it provides not only an estimate of the person’s isometric strength in their upper limb (Dale et al., 2014; Harbin and Olson, 2005) but also an estimate of their overall physical fitness (Robertson et al., 1996). Clinicians might now have to consider changing to measure the Isometric Endurance if a more functional grip strength measure is considered.

For the overall function required for occupations in participants with hand and wrist injury, the radial extension measure of the DTM on the non-injured side contributed to the outcome of the PRWHE. We hypothesize that the PRWHE is more based on hand function and range of motion and that radial extension assists with grip and positioning the hand in function and in initiating the hand movement during different tasks (Moritomo et al., 2007). Hence, the radial extension measure of the DTM on the non-injured side appeared to contribute to overall function required for occupations. Parish et al. (2018) support this as the hand comprises anatomical and biomechanical characteristics, allowing for the performance of intricate and flexible movements required in wrist and hand function such as the DTM movement, important for functional and occupational tasks. Moreover, participants may have relied on the non-injured hand more while performing daily tasks.

With regard to the methods adopted in the study, for the participants recruited, the difference in the proportion of males and females within each group was identified as significant (P = 0.003), with a higher recruitment percentage of males over females in the group with hand and wrist injury. The higher proportion of male participants in this study might explain an overall higher grip strength in the group with hand and wrist injury. Further, the occupation was shown to be significantly different between the two groups of participants recruited (P = 0.047). Individuals’ occupation is shown to contribute to their overall grip strength, with heavy manual workers having stronger grip strengths than office workers (Anakwe et al., 2007; Boschman et al., 2017). Although the proportion of blue- and white-collar workers in both participant groups was similar, the occupation could also have acted as covariates in grip strength measures of participants.

For the three types of grip strength measures taken in this study, traditionally, the Maximal Voluntary Isometric Grip Strength is the preferred method of measuring one’s grip strength, even though it is rarely used in the home or workplace. This study showed that Isometric Endurance is the significant contributor to usual work duties among participants with a hand and wrist injury. This concludes with our hypothesis that Isometric Endurance could be a more functional measure than one’s maximal effort. Therefore, we suggest that clinicians consider taking the Isometric Endurance when determining function required for occupations for this clinical population. Janik et al. (2020) provided the normative data that clinicians could refer to.

Several studies have found that grip strength is related to hand dominance, hand span, width and length, the circumference of the forearm and middle finger length (Abaraogu et al., 2017; Anakwe et al., 2007; Kunelius et al., 2007; MacDermid et al., 2002; Shurrab et al., 2015). Our results found that grip strength significantly correlated with the Forearm Length and Volumetry, and Forearm Length on the right hand is also found to contribute to the outcome of the DASH-W. This further validates our hypothesis that anthropometric dimensions such as the Forearm Length and Volumetry is related to grip strength and Forearm Length contributes to one’s performance of usual work duties. However, further study would be required to compare the contributions of Forearm Length and Volumetry with the reported hand span, width and length, the circumference of the forearm and middle finger length. Although we cannot alter one’s anthropometry, the information could offer clinicians some indications when working with people with a different body built.

In this study, we did a single measurement to record the Maximal Voluntary Isometric Grip Strength and Isometric Endurance as it has been found that a single grip measurement is just as reliable as those obtained through taking the mean of three trials (Hamilton et al., 1994; Innes, 1999). It can prevent fatigue among participants especially those who are in the active recovery stage (Coldham et al., 2006). When measuring the Rapid Exchange Grip Contractions, we took the average of five maximal effort grips to determine the participants’ maximal static grip (Hamilton et al., 1994). In the study, we used an electronic Jamar® Smart Hand Dynamometer. However, a hydraulic type can be used as a substitute in clinical practice. To record the participants’ anthropometric measures when taking the Forearm Length, we used a soft tape measure from the tip of the middle finger to the olecranon process and Volumetry to measure the size of the hand (Maihafer et al., 2003). This study indicated that the single and simple methods of measure could provide information on an individual’s grip strength measure. The DTM measure has been suggested as a functionally important measure of range as it is one of the most commonly used wrist motions in daily occupations. Bugden (2013); Parish et al. (2018) provided more information on the use. Our study found that the DTM measure could help clinicians when determining performance of usual work duties and overall function required for occupations for those with hand and wrist injury.

This study has several limitations. The time of the day in which the participants’ assessment session occurred (e.g., in the morning compared to in the afternoon) could have affected the results as some of the participants may perform differently depending on the time of the day. However, the assessment time was not recorded, and further analysis to review the possible effects could not be completed. The selection of measures not covering all others such as forearm rotation, wrist flexion/extension, and thumb and finger range of motion may limit the study findings. The investigator who conducted all the assessments was not blinded to the study aims. The adoption of the first aim to estimate the sample size did not reflect the actual sample size required to answer the second and the third aims. There was also a comparatively small sample size, which makes it difficult to provide results that are generalizable to this particular population. With this small sample size, the demographic characteristics such as sex, age, type of occupation for group 1 and group 2 participants should have been matched. The selection of participants with pain-free grip might also limit the generalizability of the findings to broader clinical populations as pain could be a primary factor in the recovery process. The data analysis methods adopted might pose a major limitation to the results generated. The use of multiple comparisons and stepwise linear regression analysis, the selection of independent variables and combining participants with and without hand and wrist injury may not result in the most plausible method of analysis to understand the matter. Future research could consider randomizing the assessment time, recruiting a larger sample size or a matched sample, and investigating and understanding the relationships between measures on a larger sample without any hand and wrist injury.

Conclusion

This study concluded that the three grip measures (Maximal Voluntary Isometric Grip Strength, Rapid Exchange, and Isometric Endurance) had moderate to strong correlation with the Forearm Length and Volumetry in participants without hand and wrist injury, and with Volumetry in participants with hand and wrist injury. Isometric Endurance of both hands was the contributing factor for one’s performance of usual work duties. Therefore, clinicians could consider using Isometric Endurance to reflect on grip strength in the rehabilitation of people with hand and wrist injury. Further study on the clinical utility of the measures is suggested.

During the development, progress, and reporting of the submitted research, Patient and Public Involvement in the research was included at all stages of the research.

Key findings

• Isometric Endurance on both hands and ulnar flexion on the right-hand assist in occupations in the workplace.

• Functional range, including ulnar flexion and radial extension, contributes to one’s overall function.

What the study has added

Isometric Endurance may be considered a more functional measure than the conventional Maximal Voluntary Isometric Grip Strength and Rapid Exchange Grip Contractions.

Footnotes

Acknowledgments

The authors would like to thank all participants in this study. and South Eastern Sydney Local Health District for supporting this project

Research ethics

The research was approved by the South Eastern Sydney Local Health District Human Research Ethics Committee (HREC ref no: 17/338 on 20 February 2018).

Declaration of conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

Patient and public involvement data

During the development, progress, and reporting of the submitted research, Patient and Public Involvement in the research was included at all stages of the research.

Contributorship

Karen PY Liu and Benjamin Bugden developed the study and were involved in the study design. Eliza Hogarth and Benjamin Bugden collected the data. Benjamin Bugden, Eliza Hogarth, and Karen PY Liu monitored the data collection. All authors contributed to assimilation of findings. Eliza Hogarth and Karen PY Liu drafted the manuscript. All authors provided critical revisions of the manuscript prior to submission. All authors have contributed significantly, and all authors are in agreement with the content of the manuscript.

ORCID iD

Karen P.Y. Liu

References

Abaraogu

Ezema

Ofodile

, et al. (2017) Association of grip strength with anthropometric measures: height, forearm diameter, and middle finger length in young adults. Polish Annals of Medicine 24(2): 153–157.

Anakwe

Huntley

McEachan

(2007) Grip strength and forearm circumference in a healthy population. Journal of Hand Surgery (European Volume) 32(2): 203–209.

Ashton

Myers

(2004) Serial grip strength testing-Its role in assessment of wrist and hand disability. The Internet Journal of Surgery 5(2): 1–12.

Beaton

Katz

Fossel

, et al. (2001) Measuring the whole or the parts? Journal of Hand Therapy 14(2): 128–142.

Bellace

Healy

Besser

, et al. (2000) Validity of the dexter evaluation system’s jamar dynamometer attachment for assessment of hand grip strength in a normal population. Journal of Hand Therapy 13(1): 46–51.

Beumer

Lindau

(2014) Grip strength ratio: a grip strength measurement that correlates well with DASH score in different hand/wrist conditions. BMC Musculoskeletal Disorders 15(1): 336.

Boschman

Noor

Lundström

, et al. (2017) Relationships between work-related factors and musculoskeletal health with current and future work ability among male workers. International Archives of Occupational and Environmental Health 90(6): 517–526.

Bugden

(2013) A proposed method of goniometric measurement of the dart-throwers motion. Journal of Hand Therapy 26(1): 77–80. quiz 80.

Celis-Morales

Welsh

Lyall

, et al. (2018) Associations of grip strength with cardiovascular, respiratory, and cancer outcomes and all cause mortality: prospective cohort study of half a million UK Biobank participants. BMJ (Clinical Research ed.) 361: k1651.

10.

Chimera

Holmes

MWR

Gabriel

(2021) Anthropometrics and electromyography as predictors for maximal voluntary isometric wrist torque: considerations for ergonomists. Applied Ergonomics 97: 103496.

11.

Coenen

Kus

Rudolf

K-D

, et al. (2013) Do patient-reported outcome measures capture functioning aspects and environmental factors important to individuals with injuries or disorders of the hand? Journal of Hand Therapy 26(4): 332–342.

12.

Coldham

Lewis

Lee

(2006) The reliability of one vs. three grip trials in symptomatic and asymptomatic subjects. Journal of Hand Therapy 19(3): 318–327.

13.

Dale

Addison

Lester

, et al. (2014) Weak grip strength does not predict upper extremity musculoskeletal symptoms or injuries among new workers. Journal of Occupational Rehabilitation 24(2): 325–331.

14.

Driscoll

Flood

Harrison

(2008) Work-related hand and wrist injuries in Australia. Australian Government: Australian Safety and Compensation Council

15.

Fallahi

Jadidian

(2011) The effect of hand dimensions, hand shape and some anthropometric characteristics on handgrip strength in male grip athletes and non-athletes. Journal of Human Kinetics 29: 151–159.

16.

Farrell

Johnson

Duncan

, et al. (2003) The intertester and intratester reliability of hand volumetrics. Journal of Hand Therapy 16(4): 292–299.

17.

Farzad

Asgari

Dashab

, et al. (2015) Does disability correlate with impairment after hand injury? Clinical Orthopaedics & Related Research 473(11): 3470–3476.

18.

Gerodimos

Karatrantou

Psychou

, et al. (2017) Static and dynamic handgrip strength endurance: test-retest reproducibility. The Journal of Hand Surgery 42(3): e175–e184.

19.

Hamilton

Balnave

Adams

(1994) Grip strength testing reliability. Journal of Hand Therapy 7(3): 163–170.

20.

Harbin

Olson

(2005) Post-offer, pre-placement testing in industry. American Journal of Industrial Medicine 47(4): 296–307.

21.

Iida

Omokawa

Moritomo

, et al. (2012) Biomechanical study of the extensor carpi ulnaris as a dynamic wrist stabilizer. The Journal of Hand Surgery 37(12): 2456–2461.

22.

Innes

(1999) Handgrip strength testing: a review of the literature. Australian Occupational Therapy Journal 46(3): 120–140.

23.

Institute for Work and Health (2006) The disabilities of the arm, shoulder and hand (DASH) outcome measure. Available at: https://dash.iwh.on.ca.

24.

Janik

Toulotte

Seichepine

, et al. (2020) Isometric strength database for muscle maximal voluntary endurance field tests: normative data.

25.

Joughin

Gulati

Mackinnon

, et al. (1993) An evaluation of rapid exchange and simultaneous grip tests. The Journal of Hand Surgery 18(2): 245–252.

26.

Klum

Wolf

Hahn

, et al. (2012) Predicting grip strength and key pinch using anthropometric data, DASH questionnaire and wrist range of motion. Archives of Orthopaedic and Trauma Surgery 132(12): 1807–1811.

27.

Kunelius

Darzins

Cromie

, et al. (2007) Development of normative data for hand strength and anthropometric dimensions in a population of automotive workers. Work (Reading, Mass.) 28(3): 267–278.

28.

Lagerström

Nordgren

(1996) Methods for measuring maximal isometric grip strength during short and sustained contractions, including intra-rater reliability. Upsala Journal of Medical Sciences 101(3): 273–285.

29.

MacDermid

Fehr

Lindsay

(2002) The effect of physical factors on grip strength and dexterity. The British Journal of Hand Therapy 7(4): 112–118.

30.

MacDermid

Wessel

Humphrey

, et al. (2007) Validity of self-report measures of pain and disability for persons who have undergone arthroplasty for osteoarthritis of the carpometacarpal joint of the hand. Osteoarthritis and Cartilage 15(5): 524–530.

31.

Maihafer

Llewellyn

Pillar

, et al. (2003) A comparison of the figure-of-eight method and water volumetry in measurement of hand and wrist size. Journal of Hand Therapy 16(4): 305–310.

32.

Moritomo

Apergis

Herzberg

, et al. (2007) 2007 IFSSH committee report of wrist biomechanics committee: Biomechanics of the so-called dart-throwing motion of the wrist. The Journal of Hand Surgery 32(9): 1447–1453.

33.

Nicolay

Walker

(2005) Grip strength and endurance: Influences of anthropometric variation, hand dominance, and gender. International Journal of Industrial Ergonomics 35(7): 605–618.

34.

Parish

Bugden

Liu

(2018) Psychometric properties of the goniometric assessment of the Dart Thrower’s Motion. Hand Therapy 23: 110–116. DOI: 10.1177/1758998318769335.

35.

Robertson

Mullinax

Brodowicz

, et al. (1996) Muscular fatigue patterning in power grip assessment. Journal of Occupational Rehabilitation 6(1): 71–85.

36.

Shechtman

Taylor

(2000) The use of the rapid exchange grip test in detecting sincerity of effort, part II: validity of the test. Journal of Hand Therapy 13(3): 203–210.

37.

Shurrab

Mohanna

Shurrab

, et al. (2015) Experimental design to evaluate the influence of anthropometric factors on the grip force and hand force exertion. International Journal of Industrial Ergonomics 50: 9–16.

38.

Vollert

Pasqualicchio

Papenhoff

, et al. (2018) Grip strength feigning is hard to detect: an exploratory study. Journal of Hand Surgery (European Volume) 43(2): 193–198.

39.

Westbrook

Tredgett

Davis

TRC

, et al. (2002) The rapid exchange grip strength test and the detection of submaximal grip effort. The Journal of Hand Surgery 27(2): 329–333.