Incorporating Handgrip Assessment into Clinical Care: A Feasibility Test of the Healthy Aging Intervention

Abstract

Age-related muscle loss is associated with a wide range of negative consequences. Handgrip strength (HGS) assessment provides information about age-related muscle loss, and strength training is one lifestyle factor that helps preserve muscle mass. Whether information about HGS and its link to health outcomes can impact patients is unknown. The Healthy Aging intervention pairs HGS feedback with information about age-related muscle loss and protective steps one can take. Objective: The objective was to gather feasibility information of the Healthy Aging intervention. Methods: Participants (N = 177) recruited from a primary care clinic were randomly assigned to the Healthy Aging intervention (N = 86) or control condition (N = 91). Participants completed a survey that assessed readiness to engage in strength training behaviors and provided feedback on the intervention (e.g., useful, easy to understand). Results: Recruitment yielded a sample with age M = 63.03 years, SD = 13.31, 52% of whom reported having engaged in no days of strength training in the past week. Ninety one percent of patients found HGS feedback useful, and 75% found the information easy to understand. Trends in behavioral readiness to change favored the intervention. Conclusion: Results support moving towards a sufficiently powered efficacy trial of the Healthy Aging intervention.

“HGS reflects overall muscular strength among middle and older aged adults and is associated with future health outcomes.”

Introduction

Muscle loss is a natural part of the aging process.^1-3 Sarcopenia is a term encompassing age-related decreases in skeletal muscle-mass, strength and function.^4-6 Though there is no universal definition of sarcopenia, there is agreement that sarcopenia reflects substantial muscle loss and function and is common in advanced age.^7-9 Age-related muscle loss and sarcopenia have significant effects on daily living and quality of life. Muscle loss and sarcopenia are linked to a variety of adverse outcomes including functional decline and increased risk of falls, hospitalization, and post-operative complications.^10,11 Age-related muscle loss and sarcopenia are important to address because there are modifiable lifestyle factors that can mitigate these outcomes including modifications to diet and engaging in resistance or weight training.^12-16

Grip Strength and Sarcopenia

There is growing evidence that handgrip strength (HGS) is one indication of sarcopenic risk and its associated negative consequences.^8,17,18 HGS assessment is non-invasive and relatively easy to administer using a dynamometer. The assessment involves squeezing a handheld dynamometer for a standardized period of time and recording the measured force produced. Assessment can occur for either the dominant hand only, or both hands. There is no standardized protocol for HGS assessment, with different protocols varying postures and number of measurements (e.g., sitting, standing, single trial vs multiple trials).^6,19,20 While there is a call to standardize HGS assessment to make it easier to compare across studies and to improve the validity of HGS as a diagnostic tool, ²¹ there is growing consensus that HGS has the potential to serve as a vital sign of overall health throughout the lifespan.^6,22 In sum, HGS assessment is non-invasive, relatively easy to administer, and provides information about age-related muscle loss and its associated consequences. This has ignited interest in learning how to use this information to benefit patients in healthcare settings.^23,24 Our team developed the Healthy Aging intervention, an intervention designed to integrate HGS information into a healthcare setting, with the aim of helping to address age-related muscle loss and sarcopenic risk.

Healthy Aging Intervention

Effective health behavior change interventions require recipients to have sufficient background knowledge about the health condition, personalized feedback on relevant health metrics and risk status, and actionable protective steps that can be taken.^20,25-29 This perspective guided the development of the Healthy Aging intervention. There were three components to this intervention delivered using an infographic developed by the research team. To ensure sufficient background knowledge, one component of the intervention educated patients about age-related muscle loss and sarcopenia, their consequent impacts on daily living and healthy aging, and how HGS can reflect overall strength resulting from one’s lifestyle.^4,6,30,31 A second component provided personalized feedback to patients, using HGS assessment as a metric reflecting current overall strength.^29,32,33 The final intervention component provided actionable information about the utility of resistance and weight training to protect from age-related muscle loss and sarcopenia and provided participants with a simple bodyweight training plan. The three components of the Healthy Aging intervention were designed to target psychological mechanisms known to facilitate behavior change; knowledge regarding age-related muscle loss, perceived susceptibility to the consequences of age-related muscle loss, and an understanding of how to preserve muscle.^25,34-36

Although dietary improvements help reduce age-related muscle loss, the Healthy Aging intervention focused on strength training because this behavior presents fewer structural barriers. Whereas dietary adaptations require access to healthy foods and the time and knowledge to prepare them,^37,38 strength exercises can be integrated into daily living in nearly any environment.

Feasibility Studies

Primary care presents an opportune environment in which to educate middle and older aged adults about age-related muscle loss and lifestyle factors that can help preserve muscle strength and function. Yet, no studies have explored whether education about age-related muscle loss and feedback from HGS assessment has the potential to shift patients’ readiness to adopt preventative actions. Therefore, the Healthy Aging intervention was designed to be scalable in that it requires little time to administer and can be integrated into the existing clinic environment by any staff member.

A first step in the process of testing the Healthy Aging intervention was to conduct a feasibility study. Feasibility studies aim to answer the question, “Can this intervention work, within a given context or environment?”, as opposed to efficacy studies which assess, “Does this intervention work?” ³⁹ Prior to evaluating whether the Healthy Aging intervention brings about changes in behavior, we wanted to first establish the intervention could be implemented in a healthcare setting with existing resources, and that the measures assessing psychological mechanisms targeted by the intervention are appropriate and deliver usable data.

The Present Study

The present study was designed to gather evidence needed to inform a future efficacy trial of the Healthy Aging intervention. Because the long-term goal of this research is to deliver the Healthy Aging intervention in a healthcare setting such as primary care, we examined the processes central to implementing the Healthy Aging intervention in this context (e.g., recruitment, ability to manage the study with secured resources, preliminary evaluation of participant responses). The following set of objectives and feasibility questions (FQ) guided this study.

Objective 1: Gather Information Regarding the Recruitment Processes and Sample Characteristics to Inform an Efficacy Trial

• FQ1: What is the demographic composition of the sample with respect to age, race, biological sex, and current strength training?

• FQ2: What percentage of primary care patients meet the criteria for below average, average, and above average HGS?

• FQ3: What percentage of those recruited have a condition preventing them from engaging in strength training?

Objective 2: Preliminary Evaluation of Participant Responses to Intervention

• FQ4: What percentage of participants reported the handgrip feedback to be useful?

• FQ5: What percentage of participants reported the infographic was easy to understand?

• FQ6: Is there evidence that the Healthy Aging intervention influences behavioral readiness to change (knowledge, perceived vulnerability, importance, efficacy, and intention)?

Methods

Participant Recruitment

A trained research assistant (RA) recruited participants (N = 177) from the waiting room of a primary care clinic between October 2023 and February 2024. To minimize the number of participants for whom age-related muscle loss seems highly irrelevant, RAs approached individuals who appeared to be 30-years and older. The RAs described the opportunity to participate in a research study on handgrip strength and their overall health. In addition, physicians in the practice were provided with information about the study and were encouraged to advertise it during their appointments.

Procedures

Upon arrival to the study room, participants were provided with an informed consent document and the opportunity to ask questions about the study. Participants were randomly assigned to either the treatment (N = 91) or control arm (N = 86) using block randomization where days of the week were allocated to either treatment or control condition. Block randomization was used because it was easier to manage the logistics of the protocol by day. The treatment condition involved receiving the Healthy Aging intervention followed by a survey that assessed demographic information and psychological mechanisms of interest. The control condition received the survey first followed by the Healthy Aging intervention. After completing the intervention components and the survey, participants were fully debriefed about the purpose of the study. As part of this process participants responded to three open-ended questions regarding their thoughts about the intervention.

The Healthy Aging Intervention

The intervention involved providing background information about age-related muscle loss, handgrip strength, and how to preserve muscle via strength training. An infographic was used to present information to participants. The infographic took the form of the trifold brochure shown in the Supplemental Materials. RAs reviewed the information with participants to help ensure that participants gained an understanding of age-related muscle loss and its consequences, the link between HGS assessment and overall strength, and the importance of strength training in muscle preservation.

Handgrip Strength Assessment

A standing protocol was used to assess the grip strength of participants’ dominant hand^40-42 using a FINGERSK Electronic Hand Dynamometer. ⁴³ Participants were instructed to stand straight up, in a neutral position with their dominant arm bent 90° at the elbow. Participants were asked to squeeze the dynamometer as “hard as you can” for a duration of 10 seconds. This procedure was repeated two additional times, with a ten second rest between each trial for a total of three trials. Participants who were unable to stand completed the assessment seated (N = 2). These individuals were included in analysis because prior research has demonstrated no statistically significant differences in detecting HGS weakness between standing and seated protocols. ⁴⁰

Measures

Background Characteristics

Participants self-reported age, biological sex, and number of children. Highest level of education was assessed by asking participants to choose from the following list, some high school, high school, trade school, some college, 2-year or Associate’s Degree, 4-year or Bachelor’s Degree, Master’s Degree, or advanced degree (e.g., MD, PhD, JD).

Race/ethnicity was assessed by asking participants to select all the groups with which they identified using this list: African American or Black, Asian or Pacific Islander, Hispanic, Native American, White, and Other. Dummy variables were created to reflect the following groups, African American or Black, Asian or Pacific Islander, Hispanic, White, Multi-racial or Other.

Participants were asked the number of days each week they engaged in activities specifically designed to increase physical strength, for example, weightlifting, ab work, calisthenics. Participants also reported their overall health using the following scale 1 (poor), 2 (fair), 3 (good), 4 (very good), or 5 (excellent). These demographic variables were selected for inclusion to characterize the sample.

Health Condition

Participants reported whether they had a physical health condition that prevented them from strength training (0 = no, 1 = yes).

Handgrip Strength

Participants’ highest recorded dynamometer reading was compared to normative data for their age and sex to categorize them as either “Below Average,” “Average,” or “Above Average.” Comparisons were made to a normative data table. ⁴⁴ Normative comparisons could not be made for participants who did not provide either their age or biological sex on the survey, and thus these participants were not categorized.

Responses to the Intervention

Intervention Acceptability

As part of the debriefing process, participants were asked open-ended questions to probe whether they felt the handgrip feedback was useful, how easy or difficult the infographic was to understand, and how they would feel if the infographic and handgrip task was administered as part of their next doctor’s visit. Responses were reviewed and categorized by a member of the research team.

Behavioral Change Readiness

Five items assessed the five psychological components targeted by the Healthy Aging intervention. Knowledge was assessed with the item “Handgrip strength is a good indicator of one’s overall strength.” Efficacy was assessed with the item “I am confident that I can take steps necessary to slow down age-related muscle loss.” Perceived susceptibility was assessed with the item “I will experience age-related muscle loss more quickly than most people my sex and age.” Responses ranged from 1 (strongly disagree) to 7 (strongly agree). Importance was assessed with the item “Over the next year, to what extent is increasing your strength a priority for you?” Responses ranged from 1 (not a priority) to 7 (essential priority). Intentions were assessed by asking “Consider the upcoming 14-days, how likely is it that you will purposely increase your strength training activities?” Response options ranged from 0 (extremely unlikely) to 7 (extremely likely).

Data Analytic Plan

Descriptive statistics were run to provide information related to FQ1-5. Correlations were run on the primary psychological mechanisms (e.g., knowledge, perceived vulnerability) to provide information about how the measures reflected cognitions of the target sample. FQ6 was answered with a one-way Analysis of Variance (ANOVA) on the following items, knowledge, perceived susceptibility, perceived importance, efficacy, and intention. In the analysis for the intention item participants with a condition that prevented ability to engage in strength training were excluded. The one-way ANOVA for knowledge, perceived susceptibility, perceived importance, efficacy was also repeated excluding participants with a condition that prevented them from engaging in strength training. This is because those who cannot engage in strength training may consider information irrelevant and, as a result, interpret the information differently.^45,46

A set of exploratory analyses were run stratifying by age. These analyses were run to examine means of behavioral readiness to change as a function of age. Age categories were created for these analyses and were informed by research documenting how physical strength (e.g., muscle strength, functional performance) declines with age.^47-49 Three age subgroups were created that included mild decline group (age 40-60 years), accelerated decline group (age 61-74 years) and advanced loss group (age 75-87 years). The ANOVAs were re-run for the items, knowledge, perceived susceptibility, perceived importance, efficacy, and intention. In the analysis for the intention item participants with a condition that prevented ability to engage in strength training were excluded. Means and SDs are reported, whereas F-values, ps and eta squared are not reported due to the small sample sizes per cell.

Results

Objective 1: Recruitment Process and Sample Characteristics

The sample (N = 177) was recruited in about five months. Age ranged from 24-87 years (Mean = 63.03 years, SD = 13.31; Median = 66 years; Mode = 70 years). They were majority female (N = 101, 57%), nearly two-thirds of the sample reported having at least one child (62.7%) and about 15% reported having a physical health condition that prevented strength training. Just over one-third of participants (68.4%) were classified as having average handgrip strength. The modal number of days per week of strength training was 0. Characteristics of the sample are shown in Table 1.

Table 1.

Sample Characteristics.

	N (%)
Sex
Male	70 (39.5)
Female	101 (57.1)
HGS Normed
Below average	28 (15.8)
Average	121 (68.4)
Above average	22 (12.4)
Kids
None	69 (33.9)
One	31 (17.5)
Two	46 (26.0)
Three	25 (14.1)
Four or five	9 (5.1)
Race
AA/Black	65 (36.7)
Asian	7 (4.0)
Hispanic	5 (2.8)
Multi-racial	5 (2.8)
Other	10 (5.6)
White	81 (45.8)
Education
HS or less	13 (7.3)
2-year/Trade	34 (19.2)
4-year	33 (18.6)
Master’s	55 (31.1)
Advanced	40 (22.6)
Overall health
Poor	5 (2.8)
Fair	32 (18.1)
Good	59 (33.3)
Very good	67 (37.9)
Excellent	12 (6.8)
Strength training
Zero	92 (52.0)
One	19 (10.7)
Two	20 (11.3)
Three	13 (7.3)
Four	11 (6.2)
Five	13 (7.3)
Six or Seven	6 (3.4)

Note. 2-year/Trade = participants who reported trade school or some college, or 2-year degree; Percentages do not total 100 due to missing data.

Objective 2: Responses to Intervention

Acceptability

About 91% of participants found the handgrip feedback to be useful, 2.1% stated the feedback was not useful, and 2.1% were unsure if the feedback was useful. Regarding ease of understanding the infographic, 75.2% of participants reported it was easy to understand, 0.7% found it difficult to understand, and 6.2% were unsure if the infographic was easy or difficult to understand (16.6% did not provide a response to this question).

In response to the question about how they would feel if the intervention was delivered as part of a standard clinic visit, a majority reported positive feelings, where nearly 37% reported that administering this would be a good/great idea or that it would be interesting, and 10.3% explicitly reported this to be useful or helpful. About 44% reported more neutral feelings such as it would be fine/okay or “it wouldn’t bother me.” A minority of participants (1.4%) reported that this would not be good or helpful. About 3% of participant’s responses reflected something different from the above responses (e.g., participants reported not having an opinion).

Behavioral Readiness

Table 2 shows the correlations between the behavioral readiness to change variables. Correlations are generally low to moderate in magnitude, ⁵⁰ suggesting that the items assess different aspects of behavioral readiness to change. Table 3 shows the means for the items assessing behavioral readiness to change and associated p-values. Across all variables, behavioral readiness to change favored the intervention condition than in the control condition. Table 4 shows the means for the items assessing behavioral readiness to change stratified by age.

Table 2.

Correlations.

	1	2	3	4	5	6
1. Overall health	-
2. Str. Training	0.11	-
3. Knowledge	0.14+	−0.02	-
4. Susceptibility	−0.37**	−0.11	0.06	-
5. Efficacy	0.21**	0.17*	0.31**	−0.10	-
6. Importance	0.12	0.21**	0.21**	0.04	0.37**	-
7. Intention	0.16*	0.17*	0.31**	−0.13+	0.46**	0.48**

Note: ^** = P < .01, ^*P < .05, ⁺ = P < .10.

Table 3.

Behavioral Readiness to Change Means by Condition.

	Full Sample							Excluded
	Control		Intervention		F	P	Eta-squared	Control		Intervention		F	P	Eta-squared
	Mean (SD)	N	Mean (SD)	N				M (SD)	N	M (SD)	N
Know.	5.12 (1.35)	84	5.41 (1.35)	91	1.99	.16	0.01	5.10 (1.32)	70	5.48 (1.25)	71	3.06	.03	0.02
Suscep	3.31 (1.47)	85	3.64 (1.40)	91	2.43	.13	0.01	3.07 (1.37)	71	3.42 (1.43)	71	2.25	.14	0.02
Efficacy	5.48 (1.18)	85	5.79 (1.01)	91	3.50	.06	0.02	5.55 (1.22)	71	5.93 (0.96)	71	4.27	.04	0.03
Priority	5.00 (1.46)	85	5.33 (1.52)	91	2.15	.14	0.01	5.01 (1.40)	71	5.28 (1.54)	71	1.17	.28	0.01
Intention	4.07 (1.59)	71	4.44 (1.30)	71	2.67	.13	0.02	4.07 (1.59)	71	4.40 (1.30)	71	2.27	.13	0.02

Note: Full sample = analysis run on all participants; Excluded = analysis excluded those who had a condition that prevented strength training.

Table 4.

Behavioral Readiness to Change Means by Condition Stratified by Age.

Age: 36-60 years
	Control		Intervention
	Mean (SD)	N	Mean (SD)	N
Know.	5.17 (1.37)	24	5.31 (1.15)	32
Suscep	3.25 (1.33)	24	3.78 (1.10)	32
Efficacy	5.50 (1.32)	24	5.75 (0.95)	32
Priority	5.04 (1.20)	24	5.31 (1.40)	32
Intention	4.14 (1.39)	21	4.29 (1.40)	24

Note: Those with a condition that prevents strength training excluded for intention.

Discussion

HGS reflects overall muscular strength among middle and older aged adults and is associated with future health outcomes. Yet, how information about HGS and its link to health outcomes impacts patients has not previously been studied. We developed and tested the feasibility of an intervention for primary care patients to motivate changes in strength training behavior. Feasibility was supported by successful recruitment of a sample and by reports from nearly all participants that the HGS feedback was useful and the information was easy to understand. Furthermore, that our recruitment strategy yielded a sample who reported very little strength training illustrates the critical need for an intervention among primary care patients.

We also explored whether the information was associated with indicators of readiness to make behavioral changes with respect to strength training. The five items used to reflect readiness to change exhibited relationships that support their use in a future fully powered efficacy trial. The items correlated in expected ways with one another and with perceived health and past strength training behavior. Although not powered to detect statistically significant differences, analyses favored the intervention on nearly all behavioral readiness to change items suggesting promise of this low-cost psychosocial intervention, and subgroup analyses for age show a similar pattern of means. Patients who were educated about HGS, its relationship to healthy aging, and provided suggestions for how to improve strength, reported greater knowledge about HGS, susceptibility to age-related muscle loss, efficacy to take steps to improve muscular strength, and intentions to increase strength training. However, there was little impact of the intervention on perceived susceptibility which is unsurprising given that nearly 85% of the sample learned they had average or above average HGS.

Future Considerations

Findings provide insights to be considered in a future iteration. While most participants felt including this intervention as part of a clinic visit would be good and helpful, about 44% reported feeling ambivalent about its inclusion. This suggests the information could be made more valuable to patients. One possibility in this regard is to tailor the information or delivery of the educational information more closely to HGS feedback. For those whose HGS feedback is below average, more clearly connecting how improvements to strength training behaviors mitigate and even potentially reverse some muscle deficits may be viewed as most valuable. Whereas for those with average HGS, emphasizing that they can capitalize on their current health may be most impactful. For this group the information may be most impactful when HGS feedback is used as an opportunity to illustrate how small changes protect the strength and health they currently have. While these nuances may seem trivial, the way information is delivered affects how responsive individuals are to feedback. ⁵¹

Limitations and Strengths

Several limitations should be considered. First, this feasibility study was not adequately powered to test intervention effectiveness. Therefore, we cannot draw conclusions regarding whether the Healthy Aging intervention is sufficiently strong to have an impact on a range of behavioral readiness to change markers. Second, we did not collect data from physicians or clinic staff regarding their thoughts on the feasibility of incorporating the intervention into routine care which is critical for moving this into existing workflow. Finally, the relatively high proportion of participants with average HGS may have attenuated perceived susceptibility to muscle loss, potentially limiting the intervention’s impact on motivation for a majority of patients in the primary care setting. A future iteration of the intervention could focus on patients with below average handgrip strength.

The study has several notable strengths. First, we were able to recruit patients on a volunteer basis from the waiting room of a clinic and with physician referrals. This shows that patients who visit their physicians may be an apt “capture audience” for an intervention like this. Our recruitment strategy yielded a sample of older adults, a majority of whom were not engaging in strength training showing that we reached the intended group. Further, the intervention was designed to be scalable, taking less than 15-minutes and was administered by trained RAs demonstrating that a future efficacy test can be implemented with minimal disruption to existing clinic flow.

Conclusions

The results support moving towards a sufficiently powered efficacy trial of the Healthy Aging intervention. The Healthy Aging intervention is acceptable to patients and is scalable in a clinic context, key criteria when assessing feasibility of an intervention. ⁵²

ORCID iDs

Tonya Dodge https://orcid.org/0000-0002-8096-7013

Jonah Kracke-Bock https://orcid.org/0000-0002-3240-5841

Ethical Considerations

All study materials were approved by the university’s Institutional Review Board (IRB# NCR235168).

Consent to Participate

All adults who chose to participate in our study provided verbal consent before starting the study session.

Data Availability Statement

Data and analyses are available upon request to the corresponding author*.