The Science behind Eforto

Eforto measures WHO recommended biomarkers for vitality capacity

Muscle strength - maximal grip strength test

Grip strength is an established biomarker for quick assessment of the neuromuscular function and overall muscle strength.
It is indicative of bone mineral density and can signal the risk of fractures, falls, malnutrition, cognitive impairments, depression, sleep disturbances, diabetes, and multimorbidity, thereby affecting overall quality of life. Additionally, it serves as a predictor of all-cause and disease-specific mortality, future functional capacity, bone health, cognitive functions, and mental health. It also provides insights into complications related to hospitalization.

Muscle fatigability / strength-endurance - fatigue resistance test

Muscle fatigability / sustained endurance testing complements Muscle strength because:

• Muscle fatigability better reflects the endurance required for daily activities, providing a more accurate measure of functional capacity in older persons.

• It is a stronger predictor of frailty and dependency in daily living activities, identifying individuals who may need more support.

• It detects early signs of muscle function decline that grip strength might miss, allowing for timely interventions.

• Muscle fatigability is closely linked to inflammatory markers like IL-6 and TNF-α.

• Muscle fatigability is more responsive to clinical changes and treatments, such as physical therapy and anti-inflammatory medications, making it useful for monitoring intervention effectiveness.

Test: The fatigue resistance test combines maximum grip strength and muscle endurance. Participants must squeeze as hard and for as long as they can until the applied pressure falls below 50% of the maximum grip strength. This test produces the Gripwork biomarker, calculated as the area under the pressure curve. Gripwork is a biomarker for the energy and metabolism dimension of Vitality Capacity.

Capacity to Perceived Vitality Ratio (CPV-ratio) - questionnaire

The Capacity to Perceived Vitality (CPV) ratio is a novel measure that combines grip work (a measure of muscle fatigability) and self-perceived fatigue (SPF) to assess intrinsic capacity or resilience. CPV is calculated by dividing grip work, adjusted for body weight, by the SPF score: CPV = GWweight/SPF. Higher CPV scores indicate better capacity.

A low CPV ratio, indicating high fatigue, has been associated with pre-frailty in community-dwelling older adults. CPV sub-scales can help researchers and clinicians better understand the specific aspects of fatigue contributing to a low CPV ratio. For example, a low CPV-physical score might suggest that physical fatigue is a significant factor contributing to pre-frailty.

Preliminary findings suggest that the CPV ratio, particularly a low CPV ratio, could be a valuable tool for identifying older adults at risk of frailty and for guiding interventions to prevent or delay its onset.

Eforto related publications

The Eforto protocol, its methods and unique bulb form factor, is grounded in scientific and clinical evidence, reflecting our deep commitment to research.

Validity and Reliability of the Eforto® System

• De Dobbeleer, Liza, et al. “Validity and Reliability of Eforto®, a System to (Self-)Monitor Grip Strength and Muscle Fatigability in Older Persons.” Aging Clinical and Experimental Research, vol. 35, no. 4, Springer Science+Business Media, Mar. 2023, pp. 835–45

Superiority of the pneumatic bulb-based vigorimeter (dynamic grip strength) seems to be more sensitive than the clamp-based dynamometer (isometric grip strength)

• De Dobbeleer, L., et al., Martin Vigorimeter assesses muscle fatigability in older adults better than the Jamar Dynamometer. Experimental Gerontology, 2018. 111: p. 65–70.

• Sipers, Walther, et al., “The Martin Vigorimeter Represents a Reliable and More Practical Tool Than the Jamar Dynamometer to Assess Handgrip Strength in the Geriatric Patient.” Journal of the American Medical Directors Association, vol. 17, no. 5, Elsevier BV, May 2016, p. 466.e1-466.e7

• De Dobbeleer, L., et al., Muscle fatigability measured with Pneumatic and Hydraulic handgrip systems are not interchangeable. Exp Gerontol, 2020. 136: p. 110950.

• Neumann, Sina, et al. "Comparison of the Grip Strength Using the Martin-Vigorimeter and the JAMAR-Dynamometer: Establishment of Normal Values." In Vivo, vol. 31, no. 5, Stanford University Highwire Press, Sept. 2017, pp. 917-923.

• De Dobbeleer, Laurence, et al. "Comparison Between Two Different Handgrip Systems and Protocols on Force Reduction in Handgrip Assessment." Gerontology, vol. 69, 2023, pp. 1259-1268.

• "The dynamic grip strength test (vigorimeter) seems to be more sensitive than the isometric grip strength test (dynamometer) to detect functional changes in relation to disease activity."

• Coppers, B., et L. "Reduced hand function indicates higher disease activity in patients with rheumatoid and psoriatic arthritis", Ann. Rheum. Dis. 2024

• "The Martin Vigorimeter is a viable alternative to the Jamar dynamometer in Koreans, offering not only reproducible and reliable measurements of grip strength but also the advantage of being unaffected by variations in hand anthropometry."

• Lee, J.K., et al. "Reliability and Validity of the Martin Vigorimeter for Grip Strength Measurement in Korean Adults"

Muscle fatigability and self-perceived fatigue captures early signs of frailty and sarcopenia before they can be diagnosed.

• Knoop, V., et al., The interrelationship between grip work, self-perceived fatigue and pre-frailty in community-dwelling octogenarians. Experimental Gerontology, 2021. 152: p. 111440.

• De Dobbeleer, L., et al., Martin Vigorimeter assesses muscle fatigability in older adults better than the Jamar Dynamometer. Experimental Gerontology, 2018. 111: p. 65-70.

• Avlund, Kirsten. “Fatigue in Older Adults: An Early Indicator of the Aging Process?” Aging Clinical and Experimental Research, vol. 22, no. 2, Springer Science+Business Media, Apr. 2010, pp. 100–15

• Eldadah, Basil A. “Fatigue and Fatigability in Older Adults.” Pm&R, vol. 2, no. 5, Elsevier BV, May 2010, pp. 406–13

• Simonsick, Eleanor M., et al. “Assessing Fatigability in Mobility‐Intact Older Adults.” Journal of the American Geriatrics Society, vol. 62, no. 2, Wiley-Blackwell, Feb. 2014, pp. 347–51

Muscle fatigability and self-perceived fatigue are more responsive than maximal strength.

• Mets, T., et al., The influence of celecoxib on muscle fatigue resistance and mobility in elderly patients with inflammation. Am J Geriatr Pharmacother, 2004. 2(4): p. 230-8.

• Beyer, I., et al., Effects on muscle performance of NSAID treatment with piroxicam versus placebo in geriatric patients with acute infection-induced inflammation. A double blind randomized controlled trial. BMC Musculoskelet Disord, 2011. 12: p. 292.

• Bautmans, I., et al., Circulating acute phase mediators and skeletal muscle performance in hospitalized geriatric patients. J Gerontol A Biol Sci Med Sci, 2005. 60(3): p. 361-7.

• Bautmans, Ivan, Knoop, Veerle, Beyer, Ingrid, et al. "The Relationship Between Self-Perceived Fatigue, Muscle Endurance, and Circulating Markers of Inflammation in Participants of the Copenhagen Aging and Midlife Biobank (CAMB)." European Review of Aging and Physical Activity, vol. 21, no. 2, 2024.

• Knoop, Veerle, et al. "Muscle Endurance and Self-Perceived Fatigue Predict Decline in Gait Speed and Activities of Daily Living After 1-Year Follow-Up: Results From the BUTTERFLY Study." The Journals of Gerontology: Series A, vol. 78, no. 8, August 2023, pp. 1402-1409.

• Knoop, Veerle, et al. "The Interrelationship Between Grip Work, Self-Perceived Fatigue, and Pre-Frailty in Community-Dwelling Octogenarians." Experimental Gerontology, vol. 152, 2021, 111440.

Muscle fatigability and self-perceived fatigue is strongly correlated to inflammatory status and its recovery.

• Bautmans, I., et al., Muscle endurance in elderly nursing home residents is related to fatigue perception, mobility, and circulating tumor necrosis factor-alpha, interleukin-6, and heat shock protein 70. J Am Geriatr Soc, 2008. 56(3): p. 389-96.

• Arnold, P. K., et al. “Peripheral Muscle Fatigue in Hospitalised Geriatric Patients Is Associated With Circulating Markers of Inflammation.” Experimental Gerontology, vol. 95, Elsevier BV, Sept. 2017, pp. 128–35

• Bautmans, I., et al., Surgery-induced inflammation in relation to age, muscle endurance, and self-perceived fatigue. J Gerontol A Biol Sci Med Sci, 2010. 65(3): p. 266-73.

• Silva, Juscélio P., et al. “Clinical, Functional and Inflammatory Factors Associated With Muscle Fatigue and Self-perceived Fatigue in Elderly Community-dwelling Women.” PubMed, vol. 15, no. 3, National Institutes of Health, Aug. 2011, pp. 241–48

• Bautmans, I., et al., Handgrip performance in relation to self-perceived fatigue, physical functioning and circulating IL-6 in elderly persons without inflammation. BMC Geriatr, 2007. 7: p. 5.

• Bautmans, I., et al., Grip work estimation during sustained maximal contraction: validity and relationship with dependency and inflammation in elderly persons. J Nutr Health Aging, 2011. 15(8): p. 731-6.

• Mets, T., et al., The influence of celecoxib on muscle fatigue resistance and mobility in elderly patients with inflammation. Am J Geriatr Pharmacother, 2004. 2(4): p. 230-8.

• Beyer, I., et al., Effects on muscle performance of NSAID treatment with piroxicam versus placebo in geriatric patients with acute infection-induced inflammation. A double blind randomized controlled trial. BMC Musculoskelet Disord, 2011. 12: p. 292.

• Bautmans, I., et al., Circulating acute phase mediators and skeletal muscle performance in hospitalized geriatric patients. J Gerontol A Biol Sci Med Sci, 2005. 60(3): p. 361-7.

• Zembron-Lacny, Agnieszka, et al. “The Relation of Inflammaging With Skeletal Muscle Properties in Elderly Men.” American Journal of Men’s Health, vol. 13, no. 2, SAGE Publishing, Mar. 2019, p. 155798831984193

Clinical studies

Ongoing studies

Additional clinical relevance is currently evaluated in the following studies:

• Feasibility and Usability of Intrinsic Capacity Monitoring With Eforto® and Its Predictive Value for Health Outcomes in Older Community-dwelling Persons (Belgium)

  • In this study, 160 community-dwelling older adults (65 years and older) will be provided with an Eforto® system to self-monitor their muscle fatigability and self-perceived fatigue for 2 consecutive days per week during 12 months (if needed with assistance by an informal caregiver). Preferably, the participants will use their own smartphone.

  • Aims:

    1. To evaluate the usability and feasibility of self-monitoring intrinsic capacity by using the Eforto® system in the home setting.

    2. To investigate if changes and variability in intrinsic capacity as measured with Eforto® (muscle fatigability and self-perceived fatigue), are related to changes in frailty status, functional independency and quality of life.

    3. To explore whether intrinsic capacity as measured with Eforto® (muscle fatigability and self-perceived fatigue) is related to circulating inflammatory biomarkers.

  • Sponsors: Vrije Universiteit Brussels, UZ Brussel (Belgium)
    Funding: AAL, VLAIO, Horizon 2020

• Resilience in Hip Fracture patients measured with the Eforto® measurement & monitoring system (Netherlands)

  • Study objective: To evaluate the validity of grip work and self-perceived fatigue measured with the Eforto® system for monitoring hip fracture recovery and insight in resilience.

  • Study design: Prognostic cohort study, daily measurements of grip work and self-perceived fatigue in acute hip fracture patients for monitoring and predicting recovery, and insight into resilience. Additional questionnaires (TOPICS-SF and MFI-20) will be included.

  • Sponsors: Ziekenhuisgroep Twente (Netherlands)
    Funding: AAL, ZonMW, Horizon 2020

• Evolving to an integrated smart self-assessment Fatigability in Outcomes to monitor Resilience Targets in Older persons (FORTO) measurement & monitoring platform.

  • Study objective: To evaluate the predictive ability of the muscle fatiguability test to predict recovery in older adults admitted to the department of geriatric medicine.

  • Study design: Extension to the Bedside Resilience Registry, which includes daily questionnaires and follow-ups. Muscle fatiguability measurements added for FORTO study; possibility for home monitoring post-discharge.

  • Sponsors: Radboud UMC (Netherlands)
    Funding: AAL, ZonMW, Horizon 2020

• Integrated System for Healthy Ageing

  • Study start date: July 2024, duration: 12 months
    Partners: WHO, VUB (BE), UZA (BE), Leiehome (BE)
    Funding: AAL, VLAIO, Horizon 2020