Maximal Voluntary Isometric Strength Research Articles

Evaluation of hip abductor and adductor strength in the elderly: a reliability study

BackgroundIn elderly individuals an increased muscle strength contributes to the diminution of the falls risk and associated adverse events. An increasing interest in lateral control exists due to the fatal consequences of postero-lateral falls. Therefore a proper assessment of frontal plane hip muscle strength in elderly is important but remains challenging.Therefore we aimed to investigate the feasibility and repeatability of a hip abductor and adductor maximum voluntary isometric strength (MVIS) and rate of force generation (RFG) test in elderly. This represents an initial step in the development process of a new and clinically relevant test that could lead to more specific treatment protocols for this population.MethodsIn this measurement focused study hip abduction (ABD) and adduction (ADD) MVIS and RFG were tested twice within one to three hours with a dynamometer fixed to a custom made frame in a geriatric population including fallers and non-fallers. Intraclass correlation coefficient (ICCagreement), standard error of measurement (SEM), and smallest detectable difference (SDD) were determined.ResultsAll recruited persons (N = 76; mean age (SD) 80.46 (7.05) years old) completed the tests. The average time needed to complete the strength tests was 10.58 min. (1.56) per muscle group. The reliability of the hip ABD and ADD was high with ICC’sagreement ranging from 0.83 to 0.97. The SDD varied between 18.1 and 81.8% depending on the muscle group and type of strength that was evaluated.ConclusionHip abductor and adductor strength measures in older person are feasible and reliable. However, the significance of moderate changes in these measurements may be limited by the large SDD and SEM. Therefore, physical therapist should be careful when using this measure for assessing the progress of an individual person in a daily clinical use.

Neurocognitive performance and physical function do not change with physical-cognitive-mindfulness training in female laboratory technicians with chronic musculoskeletal pain: Randomized controlled trial.

Background:Cognitive and physical performance can be negatively affected by chronic pain. This study evaluates the effect of combined physical-, cognitive-, and mindfulness training (PCMT) on cognitive and physical performance.Methods:From a large pharmaceutical company in Denmark we randomly allocated 112 female laboratory technicians with chronic upper limb pain to group-based PCMT at the worksite or a reference group for 10 weeks. Neurocognitive performance was measured by the computerized central nervous system vital signs neurocognitive assessment battery. Physical function was assessed in terms of shoulder external rotation strength and rate of force development in a custom-made dynamometer setup.Results:No between-group differences (least square means [95% confidence interval]) from baseline to follow-up could be detected in any of the neurocognitive domains as measured by the central nervous system vital signs neurocognitive assessment battery, for example, Psychomotoer Speed 1.9 (−1.0 to 4.7), Reaction Time −4.0 (−19.5 to 11.6), Complex Attention −0.3 (−1.9 to 1.4), and Executive Function −0.2 (−3.5 to 3.0). Similarly, we found no change in maximal voluntary isometric strength −0.63 (−4.8 to 3.6), or rate of force development 14.8 (−12.6 to 42.2) of the shoulder external rotators. Finally, test–retest reliability of maximal voluntary contraction and rate of force development shoulder external rotation showed high reliability at 0 to 30 ms, 0 to 50 ms, 0 to 100 ms, and 0 to 200 ms with ICCs at 0.95, 0.92, 0.93, 0.92, and 0.91, respectively.Conclusion:Ten weeks of PCMT did not improve neurocognitive or physical performance.

Endocrinology of Aging From a Muscle Function Point of View: Results From the Toledo Study for Healthy Aging

IntroductionAging is a process that involves a reduction in muscle strength and anabolic hormone concentrations, which impacts significantly on health. AimTo study the hormone/total strength (H/TS) ratio as a proxy of anabolic insensitivity status in elders, and its relationship with disability, hospitalization, and mortality risk. DesignA total of 1462 persons aged ≥65 years from the Toledo Study of Healthy Aging participated in this study. Serum concentrations of insulin like growth factor 1, total and free testosterone, dehydroepiandrosterone, dehydroepiandrosterone sulfate, and 17β-estradiol were measured. Total maximal voluntary isometric strength was obtained (handgrip, shoulder, hip, and knee) using standardized techniques and equipment. Physical activity was recorded by physical activity scale for the elderly questionnaire. Associations of the H/TS ratio with hospitalization and mortality were assessed using logistic regression models, and participants stratified into quartiles for each H/TS ratio. ResultsIn women, all individual ratio H/TS models showed a strong to moderate increased risk for death and hospitalization. In men, all models revealed a significant positive association of the ratio H/TS with mortality rate but not for hospitalization (P < .01). Participants who have 2 or more H/TS ratios in the worst quartile increased the risk of hospitalization and mortality at least by 2-fold. ConclusionsWe demonstrate the main role that muscle function plays in the relationship between the hormonal status and hospitalization and mortality risk; this could be taken into consideration as a way to classify patients for hormonal therapy.

Correlations Between Changes in Undercarboxylated Osteocalcin and Muscle Function in Hypoparathyroidism.

BackgroundMuscles and bones are interconnected. Recent studies suggest that undercarboxylated osteocalcin from bone may affect muscle mass and strength. There are, however, no prospective human data on this relationship.MethodsWe previously treated patients with hypoparathyroidism with intact Parathyroid Hormone (PTH) or placebo in a six-month randomized, placebo-controlled trial and demonstrated a marked increase in undercarboxylated osteocalcin (ucOC) in the PTH-treated group. We therefore investigated if this increase correlated with changes in muscle mass, strength or function. Primarily, the muscle mass using Dual energy X-ray Absorptiometry (DXA) was measured and the maximal voluntary isometric muscle strength at the upper and lower extremities, using dynamometry, was assessed. Furthermore, repeated chair stands test, Timed Up and Go test were performed and postural stability using a stadiometer was assessed. Finally, the relationship between change in ucOC or the ratio of the changes in ucOC and total OC (ucOC%/OC%) and different measures of muscle function were analyzed, using regression analyses.ResultsThe findings indicated that ucOC%/OC% was positively and significantly associated with percentage change in max force production during elbow extension (β = 0.28, P = 0.034), however, all other associations were non-significant.ConclusionsGiven the number of statistical tests that were carried out, our one significant finding may represent a false positive. Thus the results do not support the role of ucOC in muscle function in humans with hypoparathyroidism. Our results are inconsistent with previous data from a human cross-sectional study; however, cross-sectional studies, do not allow for inference of causality. The analyses should be repeated in larger, randomized trials including healthy individuals.

Effects of rumenic acid rich conjugated linoleic acid supplementation on cognitive function and handgrip performance in older men and women

The purpose of this study was to investigate the effects of 8weeks at 6g per day of RAR CLA versus placebo on cognitive function and handgrip performance in older men and women. Sixty-five (43 women, 22 men) participants (mean±SD; age=72.4±5.9yrs; BMI=26.6±4.2kg·m−2) were randomly assigned to a RAR CLA (n=30: 10 men, 20 women) or placebo (PLA; high oleic sunflower oil; n=35: 12 men, 23 women) group in double-blind fashion and consumed 6g·d−1 of their allocated supplement for 8weeks. Before (Visit 1) and after supplementation (Visit 2), subjects completed the Serial Sevens Subtraction Test (S7), Trail Making Test Part A (TMA) and Part B (TMB), and Rey's Auditory Verbal Learning Test (RAVLT) to measure cognitive function. The RAVLT included 5, 15-item auditory word recalls (R1–5), an interference word recall (RB), a 6th word recall (R6), and a 15-item visual word recognition trial (RR). For handgrip performance, subjects completed maximal voluntary isometric handgrip strength (MVIC) testing before (MVICPRE) and after (MVICPOST) a handgrip fatigue test at 50% MVICPRE. Hand joint discomfort was measured during MVICPRE, MVICPOST, and the handgrip fatigue test. There were no treatment differences (p>0.05) for handgrip strength, handgrip fatigue, or cognitive function as measured by the Trail Making Test and Serial Seven's Subtraction Test in men or women. However, RAR CLA supplementation improved cognitive function as indicated by the RAVLT R5 in men. A qualitative examination of the mean change scores suggested that, compared to PLA, RAR CLA supplementation was associated with a small improvement in joint discomfort in both men and women. Longer-term studies are needed to more fully understand the potential impact of RAR CLA on cognitive function and hand joint discomfort in older adults, particularly in those with lower cognitive function.

Neuromuscular Adaptations After 2 and 4 Weeks of 80% Versus 30% 1 Repetition Maximum Resistance Training to Failure.

Jenkins, NDM, Housh, TJ, Buckner, SL, Bergstrom, HC, Cochrane, KC, Hill, EC, Smith, CM, Schmidt, RJ, Johnson, GO, and Cramer, JT. Neuromuscular adaptations after 2 and 4 weeks of 80% versus 30% 1 repetition maximum resistance training to failure. J Strength Cond Res 30(8): 2174-2185, 2016-The purpose of this study was to investigate the hypertrophic, strength, and neuromuscular adaptations to 2 and 4 weeks of resistance training at 80 vs. 30% 1 repetition maximum (1RM) in untrained men. Fifteen untrained men (mean ± SD; age = 21.7 ± 2.4 years; weight = 84.7 ± 23.5 kg) were randomly assigned to either a high-load (n = 7) or low-load (n = 8) resistance training group and completed forearm flexion resistance training to failure 3 times per week for 4 weeks. Forearm flexor muscle thickness (MT) and echo intensity, maximal voluntary isometric (MVIC) and 1RM strength, and the electromyographic, mechanomyographic (MMG), and percent voluntary activation (%VA) responses at 10-100% of MVIC were determined at baseline, 2, and 4 weeks of training. The MT increased from baseline (2.9 ± 0.1 cm) to week 2 (3.0 ± 0.1 cm) and to week 4 (3.1 ± 0.1 cm) for the 80 and 30% 1RM groups. MVIC increased from week 2 (121.5 ± 19.1 Nm) to week 4 (138.6 ± 22.1 Nm) and 1RM increased from baseline (16.7 ± 1.6 kg) to weeks 2 and 4 (19.2 ± 1.9 and 20.5 ± 1.8 kg) in the 80% 1RM group only. The MMG amplitude at 80 and 90% MVIC decreased from baseline to week 4, and %VA increased at 20 and 30% MVIC for both groups. Resistance training to failure at 80 vs. 30% 1RM elicited similar muscle hypertrophy, but only 80% 1RM increased muscle strength. However, these disparate strength adaptations were difficult to explain with neuromuscular adaptations because they were subtle and similar for the 80 and 30% 1RM groups.

Effect of abdominal bracing training on strength and power of trunk and lower limb muscles.

It is unknown whether maximal voluntary co-contraction of abdominal muscles, called abdominal bracing, can be a training maneuver for improving strength and power of trunk and lower limb muscles. The present study aimed to elucidate this. Twenty young adult men (23.3±1.8years) were allocated to training (TG, n=11) or control (CG, n=9) group. TG conducted an 8-week training program (3days/week) consisting of 2-s maximal abdominal bracing followed by 2-s muscle relaxation (5×10repetitions/day). Maximal voluntary isometric strength during trunk flexion and extension, hip extension, and knee extension, maximal lifting power from sitting position, and the thicknesses of abdominal muscles were measured before and after the intervention. In addition, surface electromyograms from trunk and lower limb muscles and intra-abdominal pressure (IAP) during the maximal abdominal bracing and maximal lifting tasks were also determined. After the intervention, TG showed significant increases in isometric trunk extension (+14.4%) and hip extension (+34.7%) strength and maximal lifting power (+15.6%), while CG did not show any changes in strength and power variables. Furthermore, TG had significant gains in the muscle thickness of the oblique internal (+22.4%), maximal IAP during abdominal bracing (+36.8%), and the rate of IAP rise during lifting task (+58.8%), without corresponding changes in CG. The current study indicates that a training style with maximal voluntary co-contraction of abdominal muscles can be an effective maneuver for increasing strength and power during movements involving trunk and hip extensions, without using external load.

Physical Fitness Test Of Evaluating Knee Extensor Muscle Strength And Size In University Freshmen Male Students

INTRODUCTION: It is well known that the size and strength of skeletal muscle decreases with increasing age (sarcopenia), notably in the knee extensor muscles. Recent studies have indicated that university students in Japan have low levels of physical activity, and that muscle strength of the lower extremities decreases every year. Therefore, physical fitness for university students should be focused on the size/strength of the knee extensor muscles. However, an appropriate physical fitness test to evaluate knee extensor muscle strength and size in university students has not been designed. PURPOSE: The purpose of this study was to examine the relationship between knee extensor muscle strength and size and physical fitness results in university freshmen male students. METHODS: University students from the faculty of science and engineering in Toyo University participated in the study (N=116). The muscle thickness (MTH) of 104 healthy men (aged 18-20 years) was measured at the anterior half of thigh length; they performed maximal voluntary isometric strength (MVC) of knee extensors. Physical fitness [30-second chair stand (CS-30) test, standing broad jump (SBJ), handgrip and thigh girth at 50% of thigh length (mid-thigh girth)] were also measured. RESULTS: The following were similar to the standard values of the overall Japanese population for the same age group: age (18.2 ± 0.5 years), standing height (1.71 ± 0.48 m), body mass (62.9 ± 7.9 kg), body mass index (BMI, 21.6 ± 2.6), MVC (41.4 ± 12.2 kg), MTH (52.3 ± 6.6 mm), CS-30 (33.1 ± 4.3 reps), SBJ (2.13 ± 0.20 m), handgrip (41.2 ± 6.4 kg) and mid-thigh girth (50.8 ± 4.3 cm). Knee extensor MVC was correlated with SBJ (r=0.361, p<0.001) , hand grip (r=0.523, p<0.001) and mid-thigh girth (r=0.401, p<0.001), but not with CS-30 test (r=0.126, p>0.05). Knee extensor MTH was correlated with handgrip (r=0.317, p<0.001) and mid-thigh girth (r=0.632, p<0.001), but not with SBJ (r=0.038, p>0.05) and CS-30 test (r=0.145, p>0.05). CONCLUSION: Our results indicated that the measurements of handgrip and mid-thigh girth are useful methods for evaluating knee extensor muscle strength and size, and thus they could play an important role in the physical fitness of university freshmen male students for the prevention of sarcopenia and to maintain an active life in the future.

Comparing younger and older patients after TKA: impairments, functional performance and pain

Purpose: Knee osteoarthritis (OA) is not one of the most prevalent conditions leading to disability in the elderly. However, there is also a growing prevalence in younger adults, particularly for obese individuals and those who experience joint injury. Current estimates are that over 710,000 individuals with end-stage knee OA undergo total knee arthroplasties (TKA) annually in the United States, which is an increase of over 40% compared to 2002. The incidence of TKA is projected to exceed 3.5 million by the year 2030. The increases in TKA procedures are not only associated with increases in the population of elderly patients (>70 years), but also to a rise in the number of TKAs performed in a younger population. PURPOSE: The purposes of this study were 1) to compare the preoperative clinical impairments, functional abilities, and self-report measures between subsets of younger and older patients undergoing TKA, and 2) to determine if preoperative predictors of function (clinical impairments and self-reports) are similar between subsets of younger and older patients undergoing TKA. Methods: Subsets of Younger patients, those less than 60 years, and Older patients, those more than 70 years, from our Total Knee Outcome Study were examined. Preoperative testing included impairment-based measures, functional performance tests, and pain. Impairment-based measures included active flexion (Flex) and extension (Ext) range of motion (ROM) and maximal voluntary isometric knee extension strength (MVIC). Functional performance tests included the timed up-and-go (TUG), stair climbing test (SCT), 6-minute walk (6 MW). Pain was assessed on a verbal analog scale, where patients reported average knee pain from 0–10, with 0 equal to no pain and 10 as the worst pain imaginable. Independent t-tests were used to compare the measures between groups. Stepwise linear regression was used to predict functional performance measures (dependent variable) from impairment-based measures and pain (independent variables) separately for the Younger and Older groups. Results: The Younger group was significantly heavier than the Older group (Table 1). No significant differences were observed between groups for the clinical impairments (Flex, Ext or MVIC; p > 0.320) or pain (p = 0.08). Similarly, no significant differences were observed for the TUG (p = 0.927), SCT (p = 0.864), or 6 MW (p = 0.738). Regression analyses revealed that different impairments explained functional performance for the Younger and Older groups (Table 2). For example, the factors the best explained the TUG in the Younger group were Flex ROM and pain (adj. r2 = 0.502, p = 0.001), whereas the in the Older group the factors were Flex ROM and MVIC (adj. r2 = 0.219, p = 0.002). Conclusions: While the Younger group was heavier than the Older group, different factors explained the variance in functional performance measures between the two groups, with Flex ROM consistently an important factor for function in the Younger group and MVIC consistently a factor for the Older group. These findings suggests nonoperative care, preoperative decision making, and postoperative treatment may require differing approaches for younger patients compared to the older patients who are planning or undergo TKA.Tabled 1Table 1. Descriptive statistics.YoungerOlderpN2748Pct. Women7471Height (m)1.7 ± 0.11.7 ± 0.10.737Mass (kg)103.7 ± 23.787.7 ± 20.10.009BMI (kg/mˆ2)37.2 ± 8.931.5 ± 6.40.011Age (yrs)54.1 ± 5.575.9 ± 4.7<0.001 Open table in a new tab Table 2Regression table of factors explaining functional performance measures between the Younger and Older groups. Each lineRadj. R-sqrSign. ChangepModelTUGYounger1Flex ROM0.6160.3490.0020.0022Flex ROM + Pain0.7080.5020.0440.001Older1Ext. Strength0.3970.01380.0070.0072Ext. Strength + Flex0.5050.2190.0240.002SCTYounger1Flex ROM0.6610.4080.0010.001Older1BMI0.4720.2040.0010.0012BMI + Ext. Strength0.620.3550.002<0.0016MWYounger1BMI0.7840.595<0.001<0.0012BMI + Flex ROM0.8560.7040.009<0.001Older1Flex ROM0.5070.239<0.001<0.0012Flex ROM + Pain0.6530.3980.001<0.0013Flex ROM + Pain + Ext. Strength0.710.4670.016<0.0014Flex ROM + Pain + Ext. Strength + BMI0.7570.5290.016<0.001 Open table in a new tab

Effects of early whole-body vibration treatment on knee neuromuscular function and postural control after anterior cruciate ligament reconstruction: A randomized controlled trial.

To assess the effects of adding a whole-body vibration protocol at optimal frequency (WBV-OF) to a traditional rehabilitation programme (TRP) early after anterior cruciate ligament reconstruction, on maximal strength and balance, in comparison with a traditional rehabilitation programme. A total of 34 anterior cruciate ligament reconstructed patients with hamstring-tendon graft underwent either 4 weeks of WBV-OF training in addition to a traditional rehabilitation programme, or a traditional rehabilitation programme only, starting from the first month after surgery. Patients were assessed for maximal voluntary isometric strength during both knee extension and flexion and for balance on a force platform before, 1 month after treatment and at 3-month follow-up. Strength symmetry of the knee flexor muscles improved in WBV-OF+TRP patients more than in TRP patients 1 month after treatment (mean 66% (standard deviation (SD) 15) vs 58% SD 13), and also at the 3-month follow-up (mean 77% (SD 15) vs 64% (SD 15)), with no differences in balance improvements between the groups. Adding 4-weeks of WBV-OF to a traditional rehabilitation programme 1 month after surgery is effective in improving muscle strength of the knee flexor muscles. This early intervention may be incorporated into current rehabilitation to facilitate early strength recovery of anterior cruciate ligament reconstructed patients.

A comparison of volume-equated knee extensions to failure, or not to failure, upon rating of perceived exertion and strength adaptations

The present study aimed to compare the effects of repetition duration-, volume-, and load-matched resistance training to muscular failure (MMF) or not to muscular failure (NMF) on maximal voluntary isometric knee extensor strength. This design also allowed testing of the efficacy of "5×5" training. Nine recreationally active males (age, 21.4 ± 1.2 years; height, 1.79 ± 0.07 m; weight, 78.4 ± 7.1 kg) performed unilateral resistance training at 80% of maximal torque at 2×/week for 6 weeks. Using their nondominant leg, participants performed 5 sets of 5 repetitions (NMF). Using their dominant leg, participants performed 25 repetitions in as few sets as possible (MMF). All repetitions were performed at a pace of 2 s concentric, 1 s isometric pause, and 2 s eccentric with a 2-min rest interval between sets. Analyses identified significant pre- to post-intervention strength increases for both MMF and NMF, with effect sizes (ESs) of 2.01 and 1.65, respectively, with no significant differences between conditions (p > 0.05). Peak and mean ratings of perceived exertion (RPEs) were significantly higher for MMF compared with NMF conditions (p < 0.0001), and a tendency for significantly higher RPE values reported for later sets for the NMF condition. Total training time per session was significantly longer for NMF compared with MMF (p < 0.001). The present study suggests that in untrained participants, resistance training NMF produces equivocally the same strength increases as training to MMF when volume-matched. However, resistance training to MMF appears to be a more time-efficient protocol and may produce greater strength gains as indicated by a larger ES.

Muscle weakness does not influence gait in unilateral cerebral palsy: A muscle strength and three-dimensional gait analysis study

Objective. The purpose of this cross-sectional study was to investigate muscle strength and possible influence on gait in high-functioning young individuals with unilateral cerebral palsy. Methods. Forty-four individuals with a mean age of 17.5 years (range 13.0–24.0 years) and 23 matched controls participated. Maximal voluntary isometric contraction was measured in a muscle strength chair. Maximal moments (torque) and muscle work were calculated from three-dimensional gait analysis. Results. The mean maximal voluntary isometric strength in knee extensors on the involved side was 1.56 Nm/kg, compared to 2.4 Nm/kg in the control group (p < 0.001). Plantar flexor strength was 1.29 compared to 2.30 Nm/kg (p < 0.001) and dorsiflexor strength was 0.18 compared to 0.47 Nm/kg (p < 0.001). Muscle strength did not correlate with muscle work performed during walking. The respective percentages of strength (Nm/kg) used during walking in relation to the strength chair measurements were 28% for knee extensors on the involved side, 102% for plantar flexors and 41% for dorsiflexors. The corresponding numbers in the control group were 33%, 66% and 48%. Conclusion. Muscle strength is decreased in the knee and ankle on the involved side in unilateral cerebral palsy, although this does not influence gait.

Impaired Quadriceps Rate of Torque Development and Knee Mechanics After Anterior Cruciate Ligament Reconstruction With Patellar Tendon Autograft

Background: Rate of torque development (RTD) measures the ability of a muscle to produce torque quickly. Decreased quadriceps RTD may impair performance of sporting tasks after surgery. Currently, little is known about variations in quadriceps RTD between anterior cruciate ligament (ACL)–reconstructed and noninjured limbs. Purpose: To determine the differences in RTD of the quadriceps, the rate and timing of knee extensor moment (KEM) development, and knee flexion excursion during running after ACL reconstruction with patellar tendon autograft. Study Design: Cross-sectional study; Level of evidence, 3. Methods: This study involved 21 patients (11 female) 6 months after ACL reconstruction with patellar tendon autograft (median [IQR]: age, 18 [16-20] years; mass, 68.18 [61.34-75] kg; height, 1.74 [1.66-1.78] m). Patients performed four 5-second maximal voluntary isometric strength trials of both limbs on an isokinetic dynamometer. RTD was calculated as the mean slope of the torque-time curve between 20% and 80% of total time to peak torque. Then, patients underwent 3-dimensional motion analysis while running on an instrumented treadmill at a self-selected running speed (mean ± SD, 2.68 ± 0.28 m/s). The rate of knee extensor moment (RKEM) was calculated as the mean slope of the moment curve between 10% and 30% of stance phase. Between-limb comparisons were determined with a paired t test for peak KEM, RKEM, knee flexion excursion during 10% to 30% of stance, and time to generate KEM. Results: In the reconstructed limb, deficits in the peak rate of quadriceps torque development compared with the noninjured limb existed both isometrically (RTD, 257.56 vs 569.11 Nm/s; P < .001) and dynamically (RKEM, 16.47 vs 22.38 Nm/kg·m·s; P < .001). The reconstructed limb also generated a KEM later in the stance phase compared with the noninjured limb (11.37% vs 9.61% stance; P < .001) and underwent less knee flexion excursion (15.5° vs 19.8°; P < .001). Conclusion: After ACL reconstruction with patellar tendon autograft, patients have lower RTD and RKEM in the reconstructed limb. Deviations in RTD and the timing of the KEM can change the way the knee is loaded and can potentially increase injury risk and future development of posttraumatic osteoarthritis. Rehabilitation should consider exercises designed to improve RTD and prepare the limb for the demands of sport performance.

Association of regional muscle strength with mortality and hospitalisation in older people.

the association between muscular strength, mortality and hospitalisation with ageing can change depending on sex and the body region analysed (e.g. upper and lower limb muscles). to determine the effect of measuring lower and upper extremities muscular strength on the relationship between strength, mortality and hospitalisation risk in elder men and women. a population-based cohort study using data from the Toledo Study for Healthy Aging (TSHA). a Spanish population sample of 1,755 elders aged ≥65 years participated in this study. Upper (handgrip and shoulder) and lower limbs (knee and hip) maximal voluntary isometric strength was obtained using standardised techniques and equipment. Cox proportional hazards model was used to examine mortality and hospitalisation over 5.5 and 3 years of follow-up, respectively. after adjustment for potential confounding factors, including co-morbidities and BMI, hazard ratio of death and hospitalisation was significantly lower in the stronger women and men, but showing regional- and sex-specific differences. That is shoulder, knee and hip muscle regions in women and handgrip and shoulder in men (all P < 0.05). There was a cumulative effect of measuring several muscle strengths over the risk of health events (P < 0.05), so that mortality hazard ratio increased by 45% in women and 25% in men per muscular strength (shoulder, grip, knee and hip) in the weaker strength quartile increase (P < 0.01). regional muscle strength is a predictor of medium-term mortality and hospitalisation in elder men and women. Multiple strength measures including lower and upper body limb muscles are better predictors than a single strength measurement.

Does The Weaker Limb Limit Physical Performance In Older Adults?

PURPOSE: The purpose of this study was to examine the relationship of unilateral knee extensor strength asymmetry to physical function in adults at risk of mobility-limitation. METHODS: 30 subjects (75.2±6.9 yr, 167.5±9.0 cm, 74.7±14.0 kg) had their maximal voluntary isometric knee extension strength measured on a dynamometer for each limb. Subject’s percent asymmetry between the strong limb (SL) and weak limb (WL) was calculated. Those with asymmetries >10% were placed in the asymmetrical group (AG, n=14) and those <10% were placed in the symmetrical group (SG, n=16). Physical function was assessed during a timed 400m walk, chair-rise, and stair ascent. It was hypothesized that AG would have a lower level of function that was limited by the weak limb. A multivariate analysis of variance was used to examine differences in strength and performance between groups. Pearson correlations were used to study the relationship between leg strength and physical function. Significance was p<0.05. RESULTS: AG had greater strength asymmetry (22.6±15.8%) than SG (4.3±3.3%, p<0.01), lower WL strength (1.15±0.36 Nm kg-1 vs 1.55±0.43 Nm kg-1, p=0.01), but similar SL strength (1.48±0.30 Nm kg-1 vs 1.63±0.43 Nm kg-1, p=0.30). WL strength was correlated with SL strength (r = 0.90, p<0.01), 400m walk (r = -0.41, p<0.01), chair-rise (r = -0.39, p=0.01), and stair ascent (r = -0.36, p=0.01). SL strength was similarly correlated with 400m walk (r = -0.50, p<0.01), chair-rise (r = -0.40, p=0.01), and stair ascent (r = -0.42, p<0.01). There was no difference in physical function between groups (p>0.05) nor were there correlations between degree of asymmetry and physical function (p>0.05). CONCLUSION: Strength asymmetry did not limit physical function in this sample of older adults because the relative strength of each limb was more closely related to performance than the difference in strength between them, and, within an individual WL and SL strength were highly correlated. Leg strength criteria are often used to evaluate the risk of falls and mobility loss in older adults and it is currently not clear how strength asymmetry affects these relationships. Supported by: NIH Grant 1R15 A6040700-01A1

Excess Body Weight Affects Viscoelastic Properties of Triceps Surae in Older Women

Aging, inactivity, and excess body weight may negatively affect the passive work absorbing capacity of human skeletal muscle. The objective of this study was to examine the influence of excess body weight on the viscoelastic properties of the triceps surae in older women. Twenty-five women, 65-80 yr, were separated into normal weight (NW, BMI 蠄 24.9 kg m-2, n = 11) and overweight groups (OW, BMI 蠅 25.0 kg m-2, n = 14). Resistive torque of the triceps surae was recorded on an isokinetic dynamometer by passively moving the ankle from a plantarflexed to dorsiflexed position. Stiffness was calculated as the slope of the passive torque vs. position curve from 1.57 – 1.48 rad (90 – 85 deg) of dorsiflexion, and work absorption was calculated as the area under the curve. Maximal voluntary isometric strength of the triceps surae was recorded, then participants walked at maximal speed on an instrumented treadmill while muscle activation was recorded by electromyography (EMG). Stiffness was higher in NW (40.0 ± 15.7 Nm rad-1) than in OW (26.4 ± 12.7 Nm rad-1, p = 0.032), as was stiffness per kg (0.70 ± 0.28 vs. 0.37 ± 0.16 Nm rad-1 kg-1, p = 0.002). Work absorption was not statistically different between NW (0.48 ± 0.29 Nm rad) and OW (0.36 ± 0.16 Nm rad, p = 0.31) nor when expressed per kg (0.0083 ± 0.0052 vs. 0.0050 ± 0.0023 Nm rad kg-1, p = 0.078). Stiffness per kg was correlated to strength (r = 0.66, p < 0.001), peak vertical ground reaction force during walking (r = 0.72, p < 0.001), and EMG (r = -0.40, p = 0.046) with similar relationships for work absorption. OW older women have low stiffness of triceps surae, which may impair ability to absorb and return work during stretch-shortening cycles. Low stiffness in OW may limit propulsive forces during walking and necessitate greater muscle activation for active force generation. Supported by NIH L30TR000588-02

Changes in voluntary quadriceps activation predict changes in muscle strength and gait biomechanics following knee joint effusion

BackgroundIt has been hypothesized that arthrogenic muscle inhibition is responsible for altering physical function following knee injury. The association between the onset of arthrogenic muscle inhibition, measured using voluntary quadriceps activation, and changes in muscle strength and gait biomechanics are unknown. MethodsOutcomes were collected before and following a 60ml experimental knee effusion in eighteen healthy participants. Voluntary quadriceps activation was the predictor variable, while the criterion variable included, maximal voluntary isometric strength, peak knee flexion angle, peak internal knee extension moment, and peak vertical ground reaction forces during the first half of stance phase upon stair descent. Percent change scores (Δ) were imputed into linear regression equations to determine associations between predictor and criterion variables. FindingsThe variance in Δ voluntary quadriceps activation significantly predicted 87% the variance in the Δ strength (R2=0.87, P<0.001; Δ strength=−2.15+1.77Δ voluntary quadriceps activation) and 25% of the Δ vertical ground reaction force following effusion (R2=0.25, P=0.04; Δ vertical ground reaction force=−6.1+0.57 Δ voluntary quadriceps activation). After accounting for Δ knee flexion angle, Δ voluntary quadriceps activation predicted an additional 29% (Δ R2=0.29, P=0.007) of the variance in the Δ knee extension moment (R2=0.54, P=0.003, Δ knee extension moment=−10.79+0.74Δ knee flexion angle+1.64Δ voluntary quadriceps activation) following knee effusion. InterpretationImmediate quadriceps activation deficits following joint effusion result in immediate alterations in muscle strength, knee extensor moment and vertical ground reaction force during gait.

Age and gender, two key factors in the associations between physical activity and strength during the ageing process

ObjectivesThe aims of this study were to identify if the associations of physical activity (PA) and muscle strength may vary throughout the ageing process; to study the differences among genders in the relationships between PA and strength in elderly people and to test whether these differences are explained by the hormonal, nutritional and inflammatory status. Study designA total of 1741 people ≥65 years of age participated in this cross-sectional study. Main outcome measuresUpper- and lower-limbs maximal voluntary isometric strength was obtained using standardized techniques and equipment. PA was recorded by a validated questionnaire. The associations of PA with strength were assessed using generalized linear regression models with a Gamma-distributed dependent variable. ResultsA significant gender by PA interaction was found for all strength-related variables (all P<0.01). Moreover, when sexual hormones, albumin or C-Reactive protein were taken into account in the model, the results did not significantly change. In women, PA was positively associated with upper and lower-body strength; however in men, PA was only associated with grip and knee strength (both P<0.01). Higher strength values were associated with higher levels of PA, especially in women. However, this tendency had a different pattern across the age range, showing a stronger association in the ‘young’ elderly compared with the ‘old’ elderly. ConclusionHigher levels of PA are related to greater muscle strength, especially in women and those who were younger.

Functional capacity and fear of falling in cancer patients undergoing chemotherapy

Cancer patients, particularly during chemotherapy, often encounter functional status limitations. This study examines fear of falling, balance, gait and lower limb strength in cancer patients during ongoing or recently completed (≤12 months) chemotherapeutic treatment in comparison to age-matched and senior controls (≥65 years). Data were obtained from 69 subjects; 21 cancer patients (51±7 years) with histological confirmed diagnosis and two control groups (2×n=24): one age-matched (53±7 years) and one senior group (70±3 years). Fear of falling (FoF) was evaluated using the Falls Efficacy Scale-International Version. Motor function measurement included postural sway (centre of pressure) in upright stance with eyes covered, gait speed (comfortable fluid walking) and maximum voluntary isometric quadriceps strength (MIVF). One-way ANOVA followed by corrected post hoc paired-sample t-test revealed inferior values in cancer patients than in age-matched healthy regarding all parameters. Gait speed and MIVF of cancer patients were higher than in the senior control group (p<.05), whereas their FoF and postural sway were comparable (p>.05). Physical performance parameters of cancer patients were found to be lower in comparison to healthy age-matched subjects. Cancer patients show physical impairments which may limit independence and may increase fall risk. The present findings call for routine screening of physical function in cancer patients, and further stress the relevance of exercise interventions during and after chemotherapy.

Quadriceps rate of force development affects gait and function in people with knee osteoarthritis

Quadriceps weakness exists in people with knee osteoarthritis (OA), but other muscle factors like rate of force development (RFD) may also be affected by knee OA. The purpose of this study was to determine if people with knee OA have deficits in quadriceps RFD, determine if quadriceps RFD would improve predicting knee joint power absorption and generation during free and fast walking, and determine if RFD would improve predicting functional outcomes. 26 subjects with knee OA and 23 healthy control subjects performed maximal voluntary isometric strength (MVIC) and RFD measures of the quadriceps. Subjects also underwent a 3-D motion analysis of both self-selected free and self-selected fast walking speeds. Joint kinetics were calculated from inverse dynamics. RFD was not different by group (p = 0.763), however, the OA subjects generated the highest peak RFD at a lower % MVIC (p = 0.008). Controls walked significantly faster at both free and fast walking speeds (p = 0.001, p = 0.029). Knee angles at heel strike and peak knee extension were lower (p = 0.004, p = 0.027) in the OA group. During fast walking knee power generation was higher in controls (p = 0.028). MVIC and force of highest peak RFD predicted KOOS-ADL score in the OA subjects, but only MVIC predicted stair climbing time. The submaximal force at which peak RFD occurs plays a significant role in knee joint power as well as functional measures in the OA subjects, providing further evidence that factors other than maximal strength are also important in people with knee OA.