Lower Extremity Muscle Strength in 6- to 8-Year-Old Children Using Hand-Held Dynamometry

Isometric muscle strength in children and adolescents using Handheld dynamometry: reliability and normative data for the Brazilian population

"Stroke is a leading cause of disability worldwide. The most commonly stated goal following stroke is to regain the ability to walk independently, resulting in a large amount of rehabilitation time focussed on gait retraining. Identification of key variables that relate to and affect gait function is important in order to understand the factors associated with impaired gait and to guide future intervention strategies. Reduced muscle strength has been proposed as a key contributor to physical limitations after stroke and is commonly assessed in clinical and research settings. The aim of this thesis was to examine the associations between lower limb isometric strength and gait following stroke. A systematic literature review was conducted for Study One in order to collate the results of previous research which reported on the correlations between muscle strength and gait velocity following stroke. The review identified 21 articles that had examined this association with varied results. The majority of the identified studies had a small sample size (n ≤ 30) and received low scores for methodological quality. The studies with a larger sample size and methodological quality revealed a trend which suggested the strength of the ankle dorsiflexors provides the strongest bivariate association with gait velocity. Due to the limitations of the included studies, further research is needed. Another important consideration of muscle function is not only the peak amount of force a muscle group can produce (muscle strength) but how quickly force can be produced (muscle power). The second study of this thesis examined the psychometric properties of a clinically accessible device, hand-held dynamometry, for assessment of isometric muscle strength and power. The results from Study Two showed that hand-held dynamometry demonstrated acceptable reliability across eight lower limb muscle groups for the assessment of isometric strength and power in a healthy and unimpaired cohort. Concurrent validity of hand-held dynamometry also demonstrated acceptable results for the majority of lower limb muscle groups when compared against a laboratory-based fixed dynamometer. The muscle groups of the ankle were found to have lower than expected validity, however this may be due to the ankle attachment used on the fixed dynamometer, which demonstrated larger measurement error. Nevertheless, hand-held dynamometry has shown promising results for assessment of strength and power for the muscles of the lower limb in a sample of adults without impairments. To expand on the results of the systematic review (Study One), Study Three provided a detailed analysis of the relationships between isometric strength and gait velocity following stroke, as well as examining a previously underutilised outcome measure in the stroke population, isometric muscle power. Study Three was undertaken to examine if isometric power provided additional value in the relationship with gait velocity over muscle strength and to determine which muscle group of the lower limb demonstrates the strongest relationship with gait velocity. Results revealed isometric strength provided significant additional value in the relationship with gait velocity over isometric power. Comparison of seven lower limb muscle groups revealed the strength of the ankle plantarflexors and hip flexors to explain the most variance in gait velocity. The final study of this thesis (Study Four) examined the relationship between isometric measures of strength and power, assessed with hand-held dynamometry, and joint power generation during gait following stroke. Ankle plantarflexor strength and power showed a significant relationship with peak ankle joint power generation during gait. Similar to Study Three, comparison between strength and power revealed ankle plantarflexor strength had a stronger relationship over ankle plantarflexor power. The program of research presented in this thesis found hand-held dynamometry provided psychometrically-sound measures of isometric strength and power. The relationship between hand-held dynamometry derived measures of strength and power with gait function revealed isometric strength provided additional value over isometric power. The strength of the ankle plantarflexors demonstrated a strong relationship with gait velocity and ankle power generation during gait. Future research may examine the ankle plantarflexors further to see if improved plantarflexor strength results in improved gait function following stroke. This thesis provides a substantial contribution to the knowledge in this field and may assist clinical decision making when considering gait function post-stroke as well as guiding future research in the design of intervention strategies aimed at improving gait."

Test-retest strength reliability: Hand-held dynamometry in community-dwelling elderly fallers

Muscle strength changes as measured by dynamometry following functional rehabilitation in individuals with spinal cord injury

Muscle strength is a key determinant of health-related physical fitness and has become a significant biological predictor of overall health and lifespan. This study aimed to characterize the development of isometric strength in the lower limbs of Chilean schoolchildren and adolescents aged 7 to 15 years. Specifically, it sought to: (a) determine when sex-based differences in lower limb strength first appear; (b) identify key developmental stages where significant gains in muscle strength occur in boys and girls; and (c) analyze the contribution of individual muscle groups to total lower limb strength while accounting for sex and age differences. This cross-sectional study evaluated the maximum isometric strength of seven lower limb muscle groups in a sample of 302 Chilean children, divided into nine age groups at one-year intervals. Hand-held dynamometry was used for isometric strength assessment. Data analysis included a two-factor analysis of variance (ANOVA) for maximum isometric strength and a stepwise multiple linear regression analysis to the entire sample. Multiple comparisons showed significant differences between the ages of 9 and 12; and sex. The narrowest age range in the progression of maximum isometric strength were: 9-11 years for knee flexors in females (p=0.0201) and 9-12 years for males (p=0.0008). Hip flexors, dorsiflexors, hip extensors and knee extensors explained the highest percentage of variance (R 2=0.897, p<0.0001) in the total lower limb strength. Our findings show that lower limb isometric strength in Chilean schoolchildren and adolescents increases from age 10, with boys outperforming girls by age 15. Hip flexors mainly explain total strength, offering a useful reference to detect within and between subject strength deficits.

This study aimed to determine feasibility and reproducibility of muscular strength measurements in young gymnasts, using hand-held dynamometry in gymnastics-specific body positions. A group of 32 male and female young gymnasts 8–11 years-old, performed different strength tests using a Nicholas Manual Muscle Tester (NMMT). The measurements were collected in 4 major muscle groups (shoulder flexors and extensors, hip flexors and extensors) at 22 different joint angular positions, with the active elbow or knee joint in full extension. The maximal strength was obtained by placing the NMMT in a distal forearm or shank position, with the gymnast in supine or prone position stabilized on a vault. A Myrin goniometer, attached on the sagittal plane near elbow or knee joint, was used to specify the shoulder and hip joint angular positions. In the majority of the measurements (18 out of 22 angular positions) the intra-class correlation coefficients revealed a good level of test-retest reliability (R = 0.80–0.88). In four cases (3 in shoulder flexors and 1 in shoulder extensors) intra-class reliability was fair, with R-values ranging from 0.70 to 0.78. The low coefficients of variation and standard errors of measurements affirmed the reproducibility of measurements. In conclusion, this study showed the feasibility and the reproducibility of shoulder and hip flexor and extensor muscles maximal strength measurements using NMMT in gymnastics-based settings.

Many studies have shown that unilateral transfemoral amputation involves asymmetric gait. Transfemoral amputation leads to muscle atrophy in a tight stump resulting in asymmetry in muscle torque between the amputated and intact limb. This research is aimed at verifying if a relationship between torque values of hip joint flexors and extensors and gait asymmetry in patients with TFA exists. Fourteen adult subjects with unilateral TFA took part in the experiment. Gait symmetry was evaluated based on the ground reaction force (GRF). Measurements of muscle torque of hip flexors and extensors were taken with a Biodex System. All measurements were taken under isokinetic (60°/s and 120°/s) and isometric conditions. The symmetry index of vertical GRF components was from 7.5 to 11.5%, and anterio-posterior GRF from 6.2 to 9.3%. The symmetry index for muscle torque was from 24.3 to 44% for flexors, from 39 to 50.5% for extensors, and from 28.6 to 50% in the flexor/extensor ratio. Gait asymmetry correlated with muscle torque in hip joint extensors. Therapy which enhances muscle torque may be an effective form of patient therapy. The patient needs to undergo evaluation of their muscle strength and have the therapy programme adjusted to their level of muscle torque deficit.

Tree sloths evolved below‐branch locomotion making them one of few mammalian taxa beyond primates for which suspension is nearly obligatory. Suspension requires strong limb flexor muscles that provide both propulsion and braking/support, and available locomotor kinetics data indicate that these roles differ between fore‐ and hindlimb pairs. Muscle structure in the pelvic limb is hypothesized to be a key anatomical correlate of function in braking/support during suspensory walking and propulsion and/or support during vertical climbing. This expectation was tested by quantifying architecture properties in the hindlimb limb musculature of brown‐throated three‐toed sloths (Bradypus variegatus: N = 7) to distinguish the roles of the flexor/extensor functional muscle groups at each joint. Measurements of muscle moment arm (rm), mass, belly length, fascicle length, pennation angle, and physiological cross‐sectional area (PCSA) were taken from n = 45 muscles. Overall, most muscles studied show properties for contractile excursion and fast joint rotational velocity. However, the flexor musculature is more massive (p = 0.048) and has larger PCSA (p = 0.003) than the extensors, especially at the knee joint and digits where well‐developed and strong flexors are capable of applying large joint torque. Moreover, selected hip flexors/extensors and knee flexors have modified long rm that can amplify applied joint torque in muscles with otherwise long, parallel fascicles, and one muscle (m. iliopsoas) was capable of moderately high power in B. variegatus. The architectural properties observed in the hip flexors and extensors match well with roles in suspensory braking and vertical propulsion, respectively, whereas strong knee flexors and digital flexors appear to be the main muscles providing suspensory support in the pelvic limb. With aid in support by the forelimbs and the use of adaptive slow locomotion and slow muscle fiber recruitment patterns, structure–function in the tensile limb systems of sloths appears to collectively represent an additional mechanism for energy conservation.

The aim of this study was to quantify the contributions of lower extremity joint torques and the mechanical power of lower extremity muscle groups to further elucidate the loadings on hamstring and the mechanics of its injury. Eight national-level male sprinters performed maximum-velocity sprint running on a synthetic track. The 3D kinematic data and ground reaction force (GRF) were collected synchronously. Intersegmental dynamics approach was used to analyze the lower extremity joint torques and power changes in the lower extremity joint muscle groups. During sprinting, the GRF during the stance phase and the motion-dependent torques (MDT) during the swing phase had a major effect on the lower extremity movements and muscle groups. Specifically, during the stance phase, torque produced and work performed by the hip and knee muscles were generally used to counteract the GRF. During the swing phase, the role of the muscle torque changed to mainly counteract the effect of MDT to control the movement direction of the lower extremity. Meanwhile, during the initial stance and late swing phases, the passive torques, namely, the ground reaction torques and MDT produced by the GRF and the inertial movement of the segments of the lower extremity, applied greater stress to the hamstring muscles.

To investigate intrarater reliability and concurrent and construct validity of muscle strength, balance, and functional mobility measures in individuals with noncongenital myotonic dystrophy type 1 (DM1). Seventy-eight adults with noncongenital DM1 participated in visit 1, and 73 of the them participated in visit 2 separated by 1 to 2 weeks. The assessments consisted of muscle strength tests with handheld dynamometry (HHD) and stationary dynamometry in the lower limb. The balance tests consisted of the step test, Timed Up and Go test, feet-together stance, tandem stance, 1-leg stance, and modified Clinical Test of Sensory Integration and Balance on a balance platform. The functional mobility tests consisted of the 10-m walk test (10mWT) and 10-times Sit-to-Stand test. The HHD and stationary dynamometry had sufficient intrarater reliability for most muscle groups on a group (SEM% ≤15%) and individual (minimal detectable difference [MDD95%] ≤30%) level, but the HHD was most reliable. Stationary dynamometry measured a higher torque than HHD for all extensor muscles, but for single individuals, none of the devices were favored. Overall, intrarater reliability and validity were sufficient only for the dynamic balance tests, not the static balance tests. Both functional mobility tests were sufficiently reliable and valid, but the 10mWT was most reliable. Overall, HHD is recommended as a reliable and valid tool for single individuals and for flexor muscles on a group level. For balance assessments, the dynamic balance tests are recommended as the most valid and reliable balance tests. Both functional mobility tests are recommended for valid and reliable outcomes, but the 10mWT was superior for reliability.

Handheld dynamometry (HHD) using external fixation has demonstrated high inter- and intra-rater reliability. Handheld dynamometry offers an objective way to quantify strength; however, setting up external stabilization devices for HHD can be time consuming. This study examined the reliability of HHD for lower extremity strength in dancers using body weight stabilization. Twenty-six pre-professional dancers (age: 20.64 ± 2.21 years) were recruited and assessed by three testers: an experienced physical therapist (ePT), a novice physical therapist (nPT), and a student physical therapist (SPT). To avoid testing fatigue, dancers were divided into two testing groups and were evaluated on separate weekends. Testers used HHD to test isometric force production of six muscle groups in the first cohort and seven dif- ferent muscle groups in the second cohort. Testing positions were standardized and utilized a "make" test protocol. Intra- class correlation coefficients (ICC), 95% confidence interval, and standard error of measurement were calculated for each position. Inter-rater reliability was > 0.75 for all ICC measures except knee extension and ankle eversion. Intra-rater reliability was > 0.75 for all ICC measures except the ePT (tester A) day 2 for hip extension, internal rotation seated, knee extension, and ankle dorsiflexion; nPT (tester B) day 1 knee flexion; and SPT (tester C) for day 1 knee extension and ankle eversion and days 1 and 2 for ankle dorsiflexion and inversion. It is concluded that HHD can reliably measure force production of hip, knee, and ankle muscle groups without use of external fixation devices.

Walking ability is related to muscle strength in children with cerebral palsy

P.33Quantified muscle testing: the right way to assess muscle strength impairments in DM1

Finswimming is a sport where athlete uses one big monofin to produce propulsion. The purpose of this study was to describe relationship between isokinetic strength of different muscle groups and 100 meters finswimming time. Study questions was: what muscle groups have relationship with finswimming time. Methods: 17 international level monfin swimmers, 9 male (age 16,9 ±1,8 yrs., height 180,0 ± 10.0 cm., weight 76.0±6.9 kg) and 8 female finswimmers ( age 17,6 ±4,7 yrs., height 170,0 ± 10.0 cm., weight 68,6 ± 13,5 kg) performed 100 meters monofin surface swim and where also tested within a two days on isokinetic dynamometer (knee, hip and trunk extensors and flexors at angular speeds of 60°/sec ). Force data at angles from 0-90 degrees with 10 degree step were used for correlation. Results: There was a strong correlation (p<0.05) between swimming time and knee extensors (r=-0.82 at angle 50°), hip flexors (r=-0.70 at angle 10°) and trunk flexors (r =-0.77 at angle 20°) in male swimmers. Surprisingly, we did not find corresponding correlations among female finswimmers. Conclusion: Current study found relationship between strength of main muscle groups and swimming speed only in male swimmers. It is expected that strength plays a role in swimming time, but the lack of relationship in female swimmers suggests at the need to introduce a measure of swimming effectiveness instead of pure resultant time. The proposed hypothesis is further supported by the high level of competence among study participants (incl. multiple European champion, and several finalists).

To study the attributes of quantitative strength testing using hand-held dynamometry (HHD) as an efficacy measure in 2 large phase 3 amyotrophic lateral sclerosis (ALS) trials. In the phase 3 trials of ceftriaxone and dexpramipexole, 513 and 943 patients, respectively, were enrolled in double-blind, randomized, placebo-controlled trials with planned follow-up of at least 1 year. Patients were studied every 3 months in the ceftriaxone study and every 2 months in the dexpramipexole study. Evaluators of HHD were trained and had to show evidence of adequate performance of strength testing; the testing paradigm involved testing 9 muscle groups in the upper and lower extremity bilaterally. Neither drug significantly affected any outcome measure. Strength measurements were evaluated by individual muscle and by megascores, which averaged scaled strength measures to produce an overall measure of muscle strength. A measure combining rate of decline with both within- and between-patient variabilities of measurement, the coefficient of variation for rate of change, was calculated, and showed that HHD overall performed slightly less well than Amyotrophic Lateral Sclerosis Functional Rating Scale-revised (ALSFRS-R) but better than vital capacity. Individual muscles were highly correlated to the identical muscles on the contralateral side, as well as to other muscles in the same body region. Strength decline was correlated both with ALSFRS-R and vital capacity. Quantitative strength testing using HHD is a reliable and reproducible measure of decline in ALS.