The Contributions of Knee Extension Strength and Hand Grip Strength to Factors Relevant to Physical Frailty: The Tanno-Sobetsu Study.

Sarcopenia is the core factor of frailty. This study specifically focused on lower limb muscle strength and examined muscle indices that indicate the risk of frailty or pre-frailty in older adults. The study included 327 community-dwelling individuals aged ≥65 years (43.7% male) who participated in the cohort. Frailty was defined based on five symptoms: weight loss, low activity level, exhaustion, weakness and slowness. Participants were classified into frail (three or more applicable), pre-frail (one to two applicable) and non-frail groups. Muscle strength (knee extension strength, toe grip strength and hand grip strength) were assessed, and appendicular muscle mass was assessed via a bioelectrical impedance analysis. The adjusted odds ratio (OR) of muscle indices for with frailty (frail group vs. pre-frail group) or pre-frailty (pre-frail group vs. non-frail group) were calculated. The prevalence of frail and pre-frail was 7% and 40%, respectively. Adjusted for age, sex, albumin and medical history, knee extension strength was significantly associated with frailty (odds ratio 0.95, 95% CI 0.92-0.98), while hand grip strength was associated with pre-frailty (odds ratio 0.92, 95% CI 0.88-0.97) but not with other muscle indices. This study is significant for identifying knee extension strength as a factor relevant to frailty in older adults considered pre-frailty, emphasizing the importance of this specific muscle measure in predicting and managing frailty.

Toe Grip strength declines earlier than hand grip strength and knee extension strength in community-dwelling older men: a cross sectional study.

BACKGROUND: The aim of this study is to examine the age-related changes in the toe grip strength and its differences from hand grip strength and knee extension strength using cross-sectional data. METHODS: Of participants aged 65 years over who underwent health checkups for lifestyle-related diseases in 2018, 307 men and women met the criteria. Toe grip strength, hand grip strength, and knee extension strength were also measured as optional tests. The participants were divided into five groups categorized by every 5 years of age (Group 65-85). The data were analyzed with multiple comparisons using the linear mixed multilevel model to examine the following categories: association between age and muscle strength, differences in the pattern of change, and gender, using the 65-69 years group as a reference. RESULTS: In men, there were interaction effects between the factors of age and muscle, but in women there were not. Toe grip strength was significantly lower in Group 70, 75, 80, and 85 in men, lower in Group 85 than in 65 in women. Hand grip strength was significantly lower in Group 85 than in 65 in both men and women. There was no significant difference in knee extension strength among the age groups for both men and women. CONCLUSIONS: The decline in toe grip strength may occur earlier and in a different pattern from hand grip strength and knee extension strength in men.

Repeated standing back extension exercise: Influence on muscle shear modulus change after lumbodorsal muscle fatigue.

BACKGROUND: In low back pain, multifidus muscle fibers reportedly exhibit increased stiffness. Low back pain was associated with lumbodorsal muscle fatigue. There is no report of using shear modulus to verify the mechanism of an immediate effect of exercise on low back pain. Here, temporary lumbodorsal muscle fatigue was created, simulating fatigue-related nonspecific low back pain. OBJECTIVE: To assess the effect of standing back extension exercise on fatigued lumbodorsal muscle based on the results of multifidus muscle elasticity measured using shear wave elastography. METHODS: Thirty-three healthy subjects were randomly divided into three groups. The subjects performed the Biering-Sorensen test as the fatigue-task of the lumbodorsal muscle before the standing back extension exercise. The fatigue-exercise group exercised five sets after completing the fatigue-task. The fatigue-non-exercise group remained standing for the same duration as the fatigue-exercise group without doing the exercise after the fatigue-task. The non-fatigue-exercise group exercised five sets of without performing the fatigue-task. As intra-group and inter-group factors, the shear modulus of the multifidus muscle was compared before and after the exercise. RESULTS: The shear modulus of the multifidus muscle after the standing back extension exercise was significantly lower in the fatigue-exercise group, and no significant decrease was observed in the fatigue-non-exercise and non-fatigue-exercise group. CONCLUSIONS: The standing back extension exercise improved the shear modulus of the fatigued multifidus muscle. Therefore, it was suggested that the change in the elasticity of fatigued muscle might lead to the prevention of low back pain caused by muscle fatigue.

Reproducibility of elastic modulus measurement of the multifidus using the shear wave elastography function of an ultrasound diagnostic device.

[Purpose] This study aimed to obtain evidence of the musculo-physiological involvement in the effect of physiotherapy on low back pain by examining the reproducibility of elasticity measurements of the multifidus muscle at different trunk angles via the shear wave elastography function of an ultrasound diagnostic device. [Participants and Methods] This study included 11 healthy adults. Measurements were conducted with participants in the prone position, and the elasticity of the superficial and deeper layers of the multifidus muscle was measured under the following 3 conditions: trunk at neutral position, trunk flexed at 40°, and trunk extended at 20°. Next, intraclass correlation coefficients (1, 1) were calculated to examine the intrarater reliability. [Results] All intraclass correlation coefficients for the superficial and deeper layers of the multifidus muscle were ≥0.85 for all 3 conditions. [Conclusion] Regardless of the trunk position, the elastic modulus measurement of inner muscles via shear wave elastography serves as an assessment of biological changes in individuals with lower back pain in response to interventions.

Change in the circulation and activity of the lower erector spinae muscles after repeated trunk extension movement.

BACKGROUND: The optimum repetition number of standing back-extension exercise (SBEE) effective for the prevention and improvement of low back pain (LBP) is unknown. OBJECTIVE: To determine the effect of physiotherapy on LBP by investigating the optimum repetition number of SBEE via optical analysis and electromyographic (EMG) examination of the multifidus muscles. METHODS: Hemodynamics and multifidus muscle activity were examined in 16 healthy adult men using near-infrared spectroscopy and surface EMG after performing repetitive SBEE. RESULTS: Oxidized hemoglobin (Oxy-Hb) levels significantly increased in the second extension phase but decreased in the third and subsequent extension phases; deoxidized hemoglobin (deOxy-Hb) levels increased in the third and subsequent extension phases. In the standing phase, no significant difference was observed; in the third and subsequent phases, Oxy-Hb levels decreased and deOxy-Hb levels increased. Muscular activity significantly decreased in the second standing phase but increased in the third and subsequent phases. No significant difference was observed in the extension phase with respect to the number of SBEE repetitions performed. In healthy individuals, hemodynamics improved up to second repetition of SBEE; subsequent repetitions may decrease hemodynamics because of increased activity of the multifidus muscles. CONCLUSIONS: In healthy individuals, hemodynamics improved up to second repetition of SBEE.

Measuring seated hip extensor strength using a handheld dynamometer: an examination of the reliability and validity of the protocol.

[Purpose] The purpose of this study was to examine the reliability and validity of measurements of hip extensor muscle strength using a handheld dynamometer (HHD) with subjects in a sitting position. In doing so, we also aimed to establish a modified method of measurement for patients with flexion contractures in the trunk and lower extremities. [Subjects and Methods] In 20 healthy males, hip extensor muscle strength was measured using a handheld dynamometer in sitting, prone, and standing positions by contracting the hip extensor muscle isometrically with the knee flexed at 90 degrees. For each position, we investigated the relative and absolute reliability and validity of the measurements, and compared muscle strength between the different positions. [Results] The reliability and validity of measurements were highest in the sitting position and higher in both the sitting and standing positions as compared with those in the prone position. [Conclusion] Our findings suggest that measurements taken in a sitting position are accurate in assessing hip extensor muscle strength and would be applicable to patients with flexion contractures in the trunk and lower extremities.