Short communicationAssessment of isometric muscle strength and rate of torque development with hand-held dynamometry: Test-retest reliability and relationship with gait velocity after stroke
Introduction
Evidence suggests that muscle weakness is a key impairment limiting gait following stroke (Bohannon, 1989). Previous studies have examined the associations between maximal strength and gait velocity after stroke (Mentiplay et al., 2015a), however, there is limited evidence that strength training improves gait in neurological rehabilitation (Salter et al., 2016, Williams et al., 2014). Rate of torque development (RTD) is defined as the change in torque over change in time during an isometric contraction (Maffiuletti et al., 2016) and indicates how quickly muscles generate force. Compared with traditional measures of strength, RTD may provide greater insight into the relationship between weakness and gait velocity. Research in other clinical populations, such as those with cerebral palsy (Moreau et al., 2012), anterior cruciate ligament reconstruction (Pua et al., 2017) and knee osteoarthritis (Winters and Rudolph, 2014), has shown isometric RTD to provide larger associations compared to isometric strength with various measures of physical function including gait. One previous study in stroke found isometric RTD demonstrated a superior relationship with gait velocity compared to strength (Pohl et al., 2002). This study by Pohl et al. (2002) only assessed the knee extensors which are not prime movers during gait (Olney et al., 1991). The ankle plantar flexors are more affected compared to proximal muscle groups post-stroke (Adams et al., 1990), and provide the majority of power generation during gait (Winter, 1983). It is possible that the isometric RTD of other muscle groups, such as the plantar flexors, may demonstrate greater relationships with gait velocity compared to the knee extensors.
To aid clinical implementation, recent iterations of hand-held dynamometry (HHD) have allowed raw data to be exported and isometric RTD processed post-assessment. Good to excellent reliability and validity has been shown for isometric RTD measures assessed with HHD in a healthy cohort (Mentiplay et al., 2015b). Additionally, isometric strength assessed with HHD in neurological populations has shown excellent reliability (Bohannon, 1986, Riddle et al., 1989). However, the properties of HHD for assessment of RTD are currently unknown following stroke. Therefore, the aim of the current study was to firstly examine the test-retest reliability of isometric strength and RTD measures using HHD, secondly to examine the associations between measures of isometric strength and RTD, and thirdly to compare the relationships of muscle strength and RTD with gait velocity after stroke. Based on similar previous research in clinical cohorts, it was hypothesised that RTD would demonstrate greater relationships with gait velocity compared to muscle strength.
Section snippets
Participants
A convenience sample of adults 21 years or older were recruited from two major hospitals in Australia and Singapore. Inclusion criteria were: (1) confirmed stroke >3 months prior; and (2) ability to walk >10 m without gait aids or orthoses. Exclusion criteria were: (1) cerebellar stroke; (2) cognitive impairment; and (3) other diagnosed comorbidities that would impact physical participation. Ethics approval was obtained from the hospitals and all participants provided written informed consent.
Results
Characteristics of the 63 recruited participants are provided in Table 1.
Discussion
Assessment of isometric strength and RTD using HHD showed good to excellent test-retest reliability. Strong to very strong correlations were shown between isometric strength and RTD, indicating potential redundancy between measures (i.e. strength and RTD predicted each other easily). Both measures of strength and RTD provided significant predictive value to gait velocity over a covariates-only model. However, strength had significantly greater relationships with gait velocity compared to RTD.
Conflict of interest
The authors declare that they have no conflict of interest.
Acknowledgements
The authors wish to thank Ms Laura Di Nicolantonio and Dr Bok Chek Wai for their generous assistance in participant recruitment. This work was supported by an Endeavour Research Fellowship (author BFM), a National Health and Medical Research Council RD Wright Biomedical Fellowship (grant ID 1090415; author RAC), and a National Health and Medical Research Council Translating Research Into Practice Fellowship (grant ID 1110837; author GW). None of the funding bodies had any involvement in the
References (23)
- et al.
Design and validation of a portable, inexpensive and multi-beam timing light system using the Nintendo Wii hand controllers
J. Sci. Med. Sport
(2011) - et al.
Rapid force generation is impaired in cerebral palsy and is related to decreased muscle size and functional mobility
Gait Posture
(2012) - et al.
Intrarater test-retest reliability of hip range of motion and hip muscle strength measurements in persons with hip osteoarthritis
Arch. Phys. Med. Rehabil.
(2008) - et al.
The distribution of muscle weakness in upper motoneuron lesions affecting the lower limb
Brain
(1990) Test-retest reliabilty of hand-held dynamometry during a single session of strength assessment
Phys. Ther.
(1986)Selected determinants of ambulatory capacity in patients with hemiplegia
Clin. Rehab.
(1989)Knee extension power, velocity and torque: relative deficits and relation to walking performance in stroke patients
Clin. Rehab.
(1992)- et al.
Measurement in Medicine: A Practical Guide
(2011) - Evans, J.D., 1996. Straightforward Statistics for the Behavioral Sciences. Brooks/Cole Publishing, Pacific Grove,...
- Harrell Jr., F.E., 2015. Regression Modeling Strategies: With Applications to Linear Models, Logistic and Ordinal...
Rate of force development: physiological and methodological considerations
Eur. J. Appl. Physiol.
Cited by (17)
Rate of torque development of paretic lower limb is an excellent predictor of walking speed in chronic stroke individuals
2022, Clinical BiomechanicsCitation Excerpt :Although the manual dynamometer used presents adequate reliability and validity, it is not the gold standard for assessing muscle performance (Mentiplay et al., 2015). Therefore, divergences may be related to the level of functionality of populations studied since Mentiplay et al. (2018) did not include individuals using walking aid or orthoses. Herein, RTD at the early phases of torque-time curve (< 100 ms) tend to exhibit high determination coefficients for walking speed if not adjusted for assistive device use and lower limb motor function, suggesting the importance of neural factors involved in RTD (e.g., motor unit discharge rate) (Aagaard et al., 2002; Maffiuletti et al., 2016) to determine walking speed post-stroke.
Accuracy and cut-off points of different models of knee extension strength analysis to identify walking performance in individuals with chronic stroke
2021, Brazilian Journal of Physical TherapyCitation Excerpt :Thus, the present study assumes that the measurement of temporal constraints may be more relevant than an attainable PT value in an unconstrained time window. The present study assumes that the rate of torque development of other muscle groups, such as the plantar flexors, might be strongly associated with gait velocity, compared with the knee extensor muscles.46 Therefore, regardless of the strength analysis model, our findings suggest that PT is limited as a predictor of walking velocity.
Five times sit-to-stand following stroke: Relationship with strength and balance
2020, Gait and PostureCitation Excerpt :Selection criteria were: ≥21 years old, ≥3 months after a non-cerebellar stroke, ability to walk ≥10 m without any assistance or gait aids, no significant cognitive impairments (≥7 on the Abbreviated Mental Test Score), and no other comorbidities that could impact upon the assessment of strength or balance. This study was a secondary analysis of previous work examining gait velocity after stroke [18,19]. All participants provided written informed consent prior to any assessments and the study had approval from ethics committees at each hospital (637-14 and 2015/2562).