vendex and Obesity

Obesity has been identified as a risk factor for osteoarthritis. For the weight-bearing joints, the combination of increased load and changed joint biomechanics could be regarded as underlying principle for this relation. This systematic review of the literature focused on the differences between obese and normal-weight subjects in biomechanics of the hip, knee and ankle joint during every day movements to summarize differences in joint load due to both higher body weight and differences in movement patterns. A systematic search, up to November 2010, was performed in the Pubmed and Embase databases. This review showed that obese individuals adjust their movement strategy of every day movements. At self-selected speed, obese individuals walked slower, with shorter and wider steps, had longer stance duration and had a greater toe-out angle compared with normal-weight individuals. Obese sit-to-stand movement was characterized by less hip flexion and greater foot displacement. Obese individuals showed altered biomechanics during every day movements. These altered biomechanics could be related to the initiation of osteoarthritis by a change in the load-bearing regions of the articular cartilage in the weight-bearing joints.

Topics: Ankle Joint; Biomechanical Phenomena; Cartilage, Articular; Hip Joint; Humans; Joints; Knee Joint; Movement; Obesity; Osteoarthritis; Posture; Range of Motion, Articular; Risk Factors; Torque; Walking; Weight-Bearing

The aim of the study was to assess the effectiveness of a hybrid training system with walking that simultaneously applies electrical stimulation to the knee extensors/flexors during walking in obese women with knee pain.. This is a randomized, single-blind (assessor), controlled trial. Twenty-eight obese women with knee pain were randomized to 12 weeks of biweekly walking with either hybrid training system with walking or with transcutaneous electrical nerve stimulation (control). Primary outcomes (maximum isokinetic knee extensor torque and maximum isokinetic knee flexor torque) and secondary outcomes (20-m walk time, chair-stand time, stair-climb time, knee pain, and knee-related quality life) were evaluated. Change-point regression analyses were used to model the interaction for the primary outcomes. Two-sample t tests were used on pre-post change scores in secondary outcomes.. Knee extensor torque increased significantly more in the hybrid training system with walking group than the control group when baseline knee extensor torque was greater than 57.2 Nm (P = 0.0033). When baseline knee flexor torque was at 30 or 50 Nm, there was a trend toward greater increase in the hybrid training system with walking group than the control group (P = 0.0566, P = 0.0737, respectively). There were no significant differences between groups in secondary outcomes.. These results suggest that hybrid training system with walking is effective for improving knee extensor torque in obese women with knee pain. However, the superiority of hybrid training system with walking may vary depending on baseline knee muscle strength.

Topics: Aged; Arthralgia; Female; Humans; Knee Joint; Middle Aged; Muscle Strength; Obesity; Resistance Training; Single-Blind Method; Torque; Transcutaneous Electric Nerve Stimulation; Treatment Outcome; Walking

Main purpose of this study was to develop a biomechanical model for the analysis of sit-to-stand movement in normal and obese subjects.. A biomechanical model describing sit-to-stand was developed using kinetic and kinematic experimental data. Trunk flexion, feet movement, knee and hip joint torques were assumed as sensible indexes to discriminate between normal and obese subjects.. Sit-to-stand is a functional task that may become difficult for certain patients. The analysis of its execution provides useful biomechanical information on the motor ability of selected subjects.. Sit-to-stand was recorded using an optoelectronic system and a force platform in 40 obese patients and 10 normal subjects. A biomechanical model was developed using inverse dynamics equations.. Kinematic and kinetic indexes evidenced differences in motion strategy between normal and obese subjects. Obese subjects rise from the chair limiting trunk flexion (mean value: 73.1 degrees ) and moving their feet backwards from initial position (mean deviation: 50 mm). Normal subjects, instead, show a higher trunk flexion (mean value: 49.2 degrees, a lower angular value between trunk and the horizontal means increased flexion) and fixed feet position (mean deviation: 5 mm). As for kinetics, obese patients show knee joint torque higher than hip torque (maximum knee torque: 0.75 Nm/kg; maximum hip torque: 0.59 Nm/kg), while normal subjects show opposite behaviour (maximum knee torque: 0.38 Nm/kg; maximum hip torque: 0.98 Nm/kg).. We found differences in motion strategy between normal and obese subjects performing sit-to-stand movement, which may be used to plan and evaluate rehabilitative treatments.

Topics: Adult; Ankle Joint; Computer Simulation; Female; Hip Joint; Humans; Joints; Knee Joint; Male; Middle Aged; Models, Biological; Movement; Obesity; Posture; Range of Motion, Articular; Shoulder Joint; Torque

The aim of the present study was to evaluate the effect of obesity on the osseointegration of implants with hydrophobic and hydrophilic surfaces.. Sixty-four male rats were distributed among four experimental groups: H-HB (Healthy/Hydrophobic): healthy animals with hydrophobic implants; H-HL (Healthy/Hydrophilic): healthy animals with hydrophilic implants; O-HB (Obese/Hydrophobic): animals with induced obesity and hydrophobic implants; O-HL (Obese/Hydrophilic): animals with induced obesity and hydrophilic implants. One hundred and twenty-eight implants were installed in the tibiae of the animals bilaterally (64 on the left tibiae and 64 on the right one) after 75 days of a specific diet (standard or high-fat diet) and euthanasia was performed in the experimental periods of 15 and 45 days after implant placement. Bone formation was assessed by biomechanical analysis (on the left tibiae of each animal), and microtomographic and histomorphometric analyses (on the right tibiae of each animal). Statistical analysis was performed using the Shapiro-Wilk test for normality and ANOVA followed by Tukey test to observe whether there was a significant difference between groups (p < 0.05); the t-test was used to compare the animals' body weight.. The biomechanical analysis showed an increase in the removal torque value of animals after 45 days in comparison to after 15 days, with the exception of O-HB groups. The microtomographic analysis demonstrated no significant differences in the mineralized bone tissue volume between the groups. In the histomorphometric analysis, the H-HL/45 day group/period demonstrated higher bone-implant contact, in comparison to H-HL/15 days and the O-HL/45 day group/period showed an increase in bone area between the implant threads, in comparison to O-HL/15 days.. In conclusion, obesity does not interfere with the osseointegration of hydrophobic and hydrophilic implants.

Topics: Animals; Dental Implants; Implants, Experimental; Male; Obesity; Osseointegration; Rats; Surface Properties; Tibia; Titanium; Torque

Obese (OB) youth demonstrate altered knee mechanics and worse lower-extremity performance compared with healthy weight (HW) youth. Our objectives were to compare sagittal plane knee landing mechanics between OB and HW youth and to examine the associations of knee and hip extension peak torque with landing mechanics in OB youth. Twenty-four OB and 24 age- and sex-matched HW youth participated. Peak torque was measured and normalized to leg lean mass. Peak knee flexion angle and peak internal knee extension moment were measured during a single-leg hop landing. Paired t tests, Pearson correlation coefficients, and Bonferroni corrections were used. OB youth demonstrated worse performance and lower knee extension (OB: 12.76 [1.38], HW: 14.03 [2.08], P = .03) and hip extension (OB: 8.59 [3.13], HW: 11.10 [2.89], P = .005) peak torque. Furthermore, OB youth demonstrated lower peak knee flexion angles (OB: 48.89 [45.41 to 52.37], HW: 56.07 [52.59 to 59.55], P = .02) and knee extension moments (OB: -1.73 [-1.89 to -1.57], HW: -2.21 [-2.37 to -2.05], P = .0001) during landing compared with HW youth. Peak torque measures were not correlated with peak knee flexion angle nor internal knee extension moment during landing in either group (P > .01). OB youth demonstrated altered landing mechanics compared with HW youth. However, no associations among peak torque measurements and knee landing mechanics were present.

Topics: Adolescent; Biomechanical Phenomena; Humans; Knee; Knee Joint; Obesity; Torque

Muscle function is a marker of current and prospective health/independence throughout life. The effects of sex and obesity (OB) on the loss of muscle function in ageing remain unresolved, with important implications for the diagnosis/monitoring of sarcopenia. To characterise in vivo knee extensors' function, we compared muscles torque and power with isometric and isokinetic tests in older men (M) and women (W), with normal range (NW) of body mass index (BMI) and OB.. In 70 sedentary older M and W (69 ± 5 years), NW and OB (i.e. BMI < 30 kg m. In absolute units, relative to BM and LLM. We confirmed sex differences in absolute, relative to BM and LLM

Topics: Aged; Aged, 80 and over; Aging; Anthropometry; Body Composition; Female; Humans; Italy; Knee; Leg; Male; Muscle Contraction; Muscle Strength; Muscle, Skeletal; Obesity; Sedentary Behavior; Sex Factors; Torque

Previous work suggest a positive skeletal muscle effect of hormone replacement therapy (HRT) on skeletal muscle characteristics This study aimed to quantify any continued positive effect of HRT even after a sustained hiatus in treatment, controlling for two key muscle modulation hormones: Estradiol (E2) and Tri-iodo-thyronine (T3).. In 61 untrained women (18-78yrs) stratified as pre-menopausal, post-menopausal without (No_HRT) and post-menopausal with (Used_HRT) HRT history, body composition, physical activity, serum E2 and T3 were assessed by dual energy x-ray absorptiometry, Baecke questionnaire and ELISA. Gastrocnemius medialis (GM) and tibialis anterior (TA) electromyographic profiles (mean power frequency (mPowerF)), isometric plantar-flexion (PF) and dorsi-flexion (DF) maximum voluntary contraction (MVC), rate of torque development (RTD), isokinetic MVC and muscle volume, were assessed using surface electromyography, dynamometry and ultrasonography. Muscle quality was quantified as MVC per unit muscle size. E2 and E2:T3 ratio were significantly lower in postmenopausal participants, and were positively correlated with RTD even after controlling for adiposity and/or age. Pre-menopausal females had greater MVC in 8/8 PF and 2/5 DF (23.7-98.1%; P<0.001-0.049) strength measures compared to No_HRT, but only 6/8 PF (17.4-42.3%; P<0.001-0.046) strength measures compared to Used_HRT. Notably, Used_HRT had significant higher MVC in 7 PF MVC (30.0%-37.7%; P = 0.006-0.031) measures than No_HRT, while premenopausal and Used_HRT had similar uncorrected muscle size or quality. In addition, this cross-sectional data suggest an annual reduction in GM muscle volume corrected for intra-muscular fat by 1.3% in No_HRT and only 0.5% in Used_HRT.. Even years after cessation of the therapy, a history of HRT is positively associated with negating the expected post-menopausal drop in muscle quantity and quality. Whilst mPowerF did not differ between groups, our work highlights positive associations between RTD against E2 and E2:T3. Notwithstanding our study limitation of single time point for blood sampling, our work is the first to illustrate an HRT attenuation of ageing-related decline in RTD. We infer from these data that high E2, even in the absence of high T3, may help maintain muscle contractile speed and quality. Thus our work is the first to points to markedly larger physiological reserves in women with a past history of HRT.

Topics: Adiposity; Adolescent; Adult; Aged; Aged, 80 and over; Aging; Body Composition; Cross-Sectional Studies; Electromyography; Estrogen Replacement Therapy; Exercise; Female; Humans; Middle Aged; Muscle Contraction; Muscle Strength; Muscle, Skeletal; Obesity; Postmenopause; Sarcopenia; Torque; Young Adult

The objective of this study is to investigate the association between muscle function, body composition, and metabolic control in adults with type 2 diabetes mellitus (DM2).. Forty-eight individuals with DM2 were divided into four groups according to the severity of obesity (body mass index [BMI]: lean [LN, n = 10], overweight [OW, n = 16], obese class I [OBI, n = 15], and obese class II [OBII, n = 7]). Absolute peak torque (TQ), relative peak torque (TQ/body weight [BW]), total work (TW), and fatigue index (FI) were assessed by means of an isokinetic dynamometer during concentric knee extensor contraction. Spearman's correlation coefficients were used to estimate the association between measurements.. Although OBII had higher insulin levels than both LN and OW groups, no significant differences were found between groups for TQ, TQ/BW, TW, and FI, as well as between metabolic variables and muscle measurements. There was a positive correlation between BMI and TQ (r. Metabolic variables do not correlate with muscle strength and endurance in DM2. However, severity of obesity measured by the BMI is positively associated with muscle force-generating capacity and endurance.

Topics: Aged; Anthropometry; Body Composition; Body Mass Index; Body Weight; Diabetes Mellitus, Type 2; Female; Humans; Knee Joint; Male; Muscle Strength; Muscle, Skeletal; Obesity; Risk Factors; Torque

The purpose of this study was to determine if muscular dimensional changes with increases in torque production are influenced by age- and obesity-related increases in intramuscular fat, and its relationship to percent body fat (%BF), echo intensity (EI), strength, and maximum walking speed. Sixty-six healthy men were categorized into 3 groups based on age and body mass index status (young normal weight [YNW], older normal weight [ONW], and older obese [OB]). Participants underwent %BF assessments, resting ultrasonography to determine muscle size (cross-sectional area [CSA]) and EI of the superficial quadriceps, and a 10-m maximum walking speed assessment. Maximal and submaximal (rest-100% MVC in 10% increments) isometric leg extension strength was assessed while changes in rectus femoris (RF) CSA, width, and depth were obtained with ultrasonography. Echo intensity and %BF were different among all groups (p ≤ .007), with the YNW and OB groups exhibiting the lowest and highest %BF and EI values, respectively. The RF increased in depth and decreased in width with increases in torque intensity for all groups. The ONW group demonstrated no change (-0.08%) in RF CSA across torque intensities, whereas the YNW group (-11.5%) showed the greatest decrease in CSA, and the OB group showed a more subtle decrease (-4.6%). Among older men, a greater change in RF CSA was related to poorer EI (r = -0.355) and higher %BF (r = -0.346), while a greater decrease in RF width was associated with faster walking speeds (r = -0.431). Examining muscular dimensional changes during contraction is a unique model to investigate the influence of muscle composition on functional performance.

Topics: Absorptiometry, Photon; Adult; Aged; Body Composition; Humans; Image Interpretation, Computer-Assisted; Isometric Contraction; Male; Middle Aged; Muscle Strength; Obesity; Quadriceps Muscle; Signal Processing, Computer-Assisted; Torque; Ultrasonography; Walking Speed

Prader-Willi Syndrome (PWS) is a form of congenital obesity characterized by excessive body fat, hypotonia, muscle weakness, and physical/cognitive disability. However, the sources of muscle dysfunction and their contribution to mobility are unclear. The purposes of this study were to 1) compare plantar flexor function between adults with and without PWS; and 2) to examine the relationship between plantar flexor function and gait speed in adults with PWS.. Participants included 10 adults with PWS, 10 adults without PWS and with obesity, and 10 adults without PWS and without obesity (matched on age and sex). Plantar flexor function was assessed using isokinetic dynamometry (peak torque [PT], early/late rate of torque development [RTD]), Hoffman reflex (H/M ratio), ultrasound imaging (cross-sectional area [CSA], echo intensity, pennation angle, and fascicle length), and peak propulsive force and plantar flexor moment during gait. Outcomes were compared between groups using one-way MANOVA. Associations between plantar flexor outcomes and gait speed were assessed using Pearson correlation in the PWS group.. Adults with PWS had lower absolute and normalized early RTD, and lower H/M ratio than controls with and without obesity; lower absolute PT and late RTD than controls with obesity (all P < 0.05). Cross-sectional area, propulsive force, and plantarflexor moment were lower, and echo intensity was higher, in adults with PWS compared with controls without obesity (all P < 0.05). Greater absolute PT (r = 0.64), absolute early RTD (r = 0.62), absolute late RTD (r = 0.64), gastrocnemii CSA (r = 0.55), and propulsive force (r = 0.58) were associated with faster gait speed (all P < 0.05).. Adults with PWS have impaired plantar flexor function likely attributable to reduced neuromuscular function and altered muscle morphology, which are associated with slower gait speeds.

Topics: Adult; Body Mass Index; Cross-Sectional Studies; Female; Foot; Humans; Male; Motor Neurons; Muscle Strength; Muscle, Skeletal; Obesity; Prader-Willi Syndrome; Reflex, Abnormal; Torque; Ultrasonography; Walking Speed; Young Adult

Theis, N, Le Warne, M, Morrison, SC, Drechsler, W, and Mahaffey, R. Absolute and allometrically scaled lower-limb strength differences between children with overweight/obesity and typical weight children. J Strength Cond Res 33(12): 3276-3283, 2019-The purpose of this study was to compare isometric and isokinetic hip, knee, and ankle strength in children with overweight/obesity (OWB) and typical weight (TW) of age 6-12 years. Absolute torque and torque allometrically scaled to body mass and fat-free mass were derived to allow for comparison of strength irrespective of body size. Using a cross-sectional design, 26 OWB (body mass index [BMI] Z score: 2.28 ± 0.77, 54% females) children were matched in age and height with 26 TW (BMI Z score: -0.39 ± 0.96, 54% females). Subjects performed maximal isometric and isokinetic contractions in ankle dorsiflexion and plantarflexion, knee flexion and extension, hip flexion and extension, and isometric hip abduction and adduction. Between-group differences in absolute and normalized isometric and isokinetic strength were compared with 1-way analysis of variances. Statistical significance was set at p < 0.05. Children with OWB had significantly greater absolute torque in the knee flexors and extensors (15-21%) and greater isokinetic ankle dorsiflexion (8%) but lower isometric hip abduction (21%) compared with TW children. When strength was allometrically scaled to body mass, children with OWB were significantly weaker at the ankle (19-25%), hip (21-36%), and in the knee extensors (12-15%). When torque was allometrically scaled to fat-free mass, children in the OWB group had greater knee flexor and extensor strength (12-14%) but were weaker in isometric hip abduction (33%) and isokinetic hip flexion and extension (29-40%). The results demonstrated that deficits in strength, relative to body mass, at the ankle and hip may be greater than those of the knee. These strength deficits in the group with OWB highlight the need for targeted musculoskeletal strength interventions to incorporate all lower-limb muscle groups.

Topics: Ankle; Ankle Joint; Body Mass Index; Child; Cross-Sectional Studies; Female; Hip Joint; Humans; Isometric Contraction; Knee Joint; Lower Extremity; Male; Muscle Strength; Muscle, Skeletal; Obesity; Torque

Obesity influences gait and muscle function, which may contribute to knee osteoarthritis. This study aimed 1) to compare gait biomechanics and quadriceps function between individuals with and without obesity and 2) to examine the association between quadriceps function and gait biomechanics.. Forty-eight individuals with and 48 without obesity participated and were matched on age and sex. Gait biomechanics at standardized and self-selected speeds were used to assess peak vertical ground reaction force (vGRF), vertical loading rate (vLR), internal knee extension moment (KEM), peak knee flexion angle (KFA), knee flexion excursion (KFE), and knee joint stiffness. Quadriceps function was assessed using peak isometric strength (peak torque), early (RTD100) and late (RTD200) rate of torque development (RTD), and vastus lateralis cross-sectional area (CSA) and echo intensity (EI).. When normalized to fat-free mass, individuals with obesity had lower RTD100 (P = 0.04) and RTD200 (P = 0.02) but higher vastus lateralis CSA (P < 0.01) and EI (P < 0.01) compared with normal weight controls. The group-speed interaction was significant for normalized vGRF (P < 0.01), normalized vLR (P = 0.02), normalized KEM (P = 0.03), and normalized knee joint stiffness (P = 0.02). Post hoc analyses indicate a smaller normalized vGRF and normalized KEM, and lower knee joint stiffness in individuals with obesity compared with normal weight controls at self-selected speed. There were main effects of speed for all kinematic and kinetic variables, and body mass index group for all absolute kinetic variables as well as normalized vGRF (all P < 0.001). A lower vastus lateralis EI (P = 0.04) and greater RTD100 (P < 0.01) were associated with a larger KEM in individuals with obesity.. Individuals with obesity have quadriceps dysfunction that is weakly associated with KEM during walking. Exercise interventions that improve quadriceps function may improve walking mechanics.

Topics: Adult; Biomechanical Phenomena; Body Composition; Case-Control Studies; Female; Gait; Humans; Knee Joint; Male; Obesity; Quadriceps Muscle; Range of Motion, Articular; Torque; Young Adult

Obesity alters whole body kinematics during activities of daily living such as sit-to-stand (STS), but the relative contributions of excess body mass and decreased relative strength are unknown.. Three-dimensional motion analysis data was collected on 18 obese subjects performing sit-to-stand (chair height: 52 cm). Isometric knee extensor strength was measured at 90. BMI, but not knee extensor torque, was inversely related to shank angle and positively related to stance width. Relative knee extensor torque, but not BMI, was inversely associated with initial trunk angle, peak trunk flexion angle, and peak trunk extension velocity (r. BMI and knee extensor strength differently contribute to sit-to-stand performance strategies in obese subjects. Muscle strength may be an important determinant of whole-body kinematics during activities of daily living such as STS.

Topics: Adult; Biomechanical Phenomena; Body Mass Index; Female; Humans; Knee Joint; Male; Middle Aged; Movement; Muscle Strength; Obesity; Posture; Range of Motion, Articular; Torque; Torso; Young Adult

There is an absence of information regarding the impact of central adiposity on loading during long duration, repetitive lifting, and very limited information of the impact of elevated body mass on mechanical loading of the lumbar spine. This information is important in evaluation of the validity of injury prevention standards and interventional approaches in this segment of the population.. This study evaluated the mechanical, physiological, and perceptual loading during repetitive lifting in participants with central adiposity compared to participants with normal body mass index. Videography, accelerometry, heart rate and perceived exertion measures were used to examine alternations in kinematic, kinetic, and exertional parameters during a 1-hour lifting task (3 × 20-min sets; 4 lifts/min; self-selected mass).. Low back torque [+69.1 (11.5) Nm], compressive force [+1036.6 (153.6) N] and heart rate [+7.0 (3.5)%] were substantially elevated in participants with central adiposity, however perceived exertion and self-selected mass did not differ between groups. With central adiposity a compensatory mechanism was observed, involving a reduction in trunk vertical displacement [-5.8 (1.9) cm], hip flexion [-6.4 (3.1) deg] and lower-trunk flexion [-10.0 (2.7) deg], which attenuated expected increases to work [9.8 (2.3)%], power [9.5 (4.0)%] and physiological effort.. While mechanical loading increases secondary to elevated body mass are expected, these results provide new insight into origins of such increases for individuals with a central adiposity somatotype. The differences in mechanical, physiological and perceived loading support provision of individual-specific injury prevention strategies, as well as revision of existing mechanical- and physiological-based ergonomic standards.

Topics: Abdominal Fat; Adiposity; Adult; Biomechanical Phenomena; Body Mass Index; Electromyography; Humans; Kinetics; Lifting; Lumbar Vertebrae; Lumbosacral Region; Male; Obesity; Range of Motion, Articular; Stress, Mechanical; Torque; Waist-Hip Ratio; Young Adult

Evidence implicates the amount and location of fat in aging-related loss of muscle function; however, whether intramyocellular lipids affect muscle contractile capacity is unknown.. We compared both in vivo knee extensor muscle strength, power, and quality and in vitro mechanical properties of vastus lateralis single-muscle fibers between normal weight (NW) and obese older adults and determined the relationship between muscle lipid content (both intramuscular adipose tissue and intramyocellular lipids) and in vivo and in vitro muscle function in NW and obese individuals.. The obese group had a greater percentage of type-I fibers compared to the NW group. The cross-sectional area of type-I fibers was greater in obese compared to NW; however, maximal shortening velocity of type-I fibers in the obese was slower compared to NW. Type-I and type-IIa fibers from obese group produced lower specific force than that of type-I and type-IIa fibers from the NW group. Normalized power was also substantially lower (~50%) in type-I fibers from obese adults. The intramyocellular lipids data showed that total lipid droplet area, number of lipid droplets, and area fraction were about twofold greater in type-I fibers from the obese compared to the NW group. Interestingly, a significant inverse relationship between average number of lipid droplets and single-fiber unloaded shortening velocity, maximal velocity, and specific power was observed in obese participants. Additionally, muscle echointensity correlated with single-fiber specific force.. These data indicate that greater intramyocellular lipids are associated with slower myofiber contraction, force, and power development in obese older adults.

Topics: Aged; Aged, 80 and over; Aging; Body Composition; Female; Humans; Lipids; Male; Muscle Contraction; Muscle Fibers, Fast-Twitch; Muscle Fibers, Skeletal; Muscle Fibers, Slow-Twitch; Muscle Strength; Obesity; Torque

The aim of this study was to investigate the effect of obesity on neuromuscular fatigue in adolescent girls.. Twelve lean (13.6 ± 0.8 years) and 12 obese (13.9 ± 0.9 years) girls repeated 5-s maximal voluntary contractions (MVC) of the knee extensors until the generated torque reached 55 % of its initial value. Magnetic stimulations were delivered to the femoral nerve every five MVCs to follow the course of voluntary activation (VA) and potentiated twitch torque (Qtwpot).. Torque reached 55 % of its initial value after 52.6 ± 20.4 and 74.9 ± 22.8 repetitions in obese and lean girls, respectively (p < 0.01). Furthermore, the decline of VA was smaller in obese girls (p < 0.001). In contrast, Qtwpot decreased to a greater extent in obese girls (p < 0.05).. Obese girls fatigue faster than their lean counterparts. The peripheral factors mainly account for fatigue in obese girls, whereas central factors are mainly involved in lean girls.

Topics: Adolescent; Child; Electric Stimulation; Electromyography; Female; Femoral Nerve; Humans; Isometric Contraction; Muscle Fatigue; Muscle Strength; Obesity; Torque

What is the central question of this study? Do obesity-specific factors affect skeletal muscle performance in older individuals? What is the main finding and its importance? Older obese women have a larger quadriceps femoris size but develop lower tension per unit of skeletal muscle than their normal-weight counterparts. Muscle impairment and excess body mass are very common among older people. Given that the effect of obesity on strength production has scarcely been studied in older individuals, we analysed functional and structural characteristics of quadriceps femoris (QF) in obese (OB) and normal-weight (NW) older women with comparable habitual physical activity. In five OB (body mass index 36.8 ± 1.9 kg m(-2), age 72.4 ± 2.3 years) and six NW well-functioning older women (body mass index 24.3 ± 1.8 kg m(-2), age 72.7 ± 1.9 years), peak knee-extension torque (KET) was measured in isometric (90 deg knee flexion) and isokinetic conditions (240, 180, 120 and 60 deg s(-1)). Mid-thigh QF cross-sectional area (CSA) and muscle tissue fat content (MF%) were determined with magnetic resonance imaging (Dixon sequence). Muscle fascicle length and pennation angle (PA) were assessed with ultrasonography for each muscle belly of the QF (vastus lateralis, vastus intermedius, rectus femoris and vastus intermedius). Despite similar values of KET, CSA was 17.0% larger in OB than in NW women (P < 0.05), so that KET/CSA was significantly lower (P < 0.05) in OB women. Compared with NW women, OB women had 28.7% higher MF% (P < 0.05) and 24.9% higher average PA (P < 0.05), while fascicle length was similar. Overall, isometric KET/CSA was negatively affected by both MF% (P < 0.05) and PA (P < 0.05), while isokinetic KET/CSA was negatively affected only by MF% (P < 0.01). Muscle composition and architecture seem to be important determinants of KET/CSA in elderly women. In fact, owing to the effect of obesity overload, OB women have a larger QF size than NW women, but unfavourable muscle composition and architecture. The higher MF% and steeper PA observed in OB women are associated with reduced levels of muscle specific strength.

Topics: Adiposity; Age Factors; Aged; Biomechanical Phenomena; Body Mass Index; Case-Control Studies; Female; Humans; Isometric Contraction; Magnetic Resonance Imaging; Muscle Strength; Muscular Diseases; Obesity; Quadriceps Muscle; Sex Factors; Torque; Ultrasonography

Although an authoritative panel recommended the use of ergometer rowing as a non-weight-bearing form of exercise for obese adults, the biomechanical characterization of ergometer rowing is strikingly absent. We examined the interaction between body mass index (BMI) relative to the lower extremity biomechanics during rowing in 10 normal weight (BMI 18-25), 10 overweight (BMI 25-30 kg·m⁻²), and 10 obese (BMI > 30 kg·m⁻²) participants. The results showed that BMI affects joint kinematics and primarily knee joint kinetics. The data revealed that high BMI leads to unfavorable knee joint torques, implying increased loads of the medial compartment in the knee joint that could be avoided by allowing more variable foot positioning on future designs of rowing ergometers.

Topics: Acceleration; Body Mass Index; Computer Simulation; Ergometry; Exercise Therapy; Female; Humans; Knee Joint; Male; Models, Biological; Obesity; Physical Exertion; Range of Motion, Articular; Ships; Torque

During seated forward reaching tasks in obese individuals, excessive abdominal tissue can come into contact with the anterior thigh. This soft tissue apposition acts as a mechanical restriction, altering functional biomechanics at the hip, and causing difficulty in certain daily activities such as bending down, or picking up objects from the floor. The purpose of the study was to investigate the contact forces and associated moments exerted by the abdomen on the thigh during seated forward-reaching tasks in adult obese individuals. Ten healthy subjects (age 58.1 ± 4.4) with elevated BMI (39.04 ± 5.02) participated in the study. Contact pressures between the abdomen and thigh were measured using a Tekscan Conformat pressure-mapping sensor during forward-reaching tasks. Kinematic and force plate data were obtained using an infrared motion capture system. The mean abdomen-thigh contact force was 10.17 ± 5.18% of body weight, ranging from 57.8 N to 200 N. Net extensor moment at the hip decreased by mean 16.5 ± 6.44% after accounting for the moment generated by abdomen-thigh tissue contact. In obese individuals, abdomen-thigh contact decreases the net moment at the hip joint during seated forward-reaching activities. This phenomenon should be taken into consideration for accurate biomechanical modeling in these individuals.

Topics: Abdomen; Adult; Computer Simulation; Female; Hip Joint; Humans; Male; Middle Aged; Models, Biological; Muscle Contraction; Muscle, Skeletal; Obesity; Pressure; Range of Motion, Articular; Task Performance and Analysis; Thigh; Torque

Obesity is a major public health problem leading to, among other things, reduced functional capacity. Moreover, obesity-related declines in functional capacity may be compounded by the detrimental consequences of menopause. The aim of this study was to understand the potential effects of excess body mass on measures of functional capacity in postmenopausal women.. Forty-five postmenopausal women aged 50 to 60 years were divided into two groups according to body mass index (BMI): obese (BMI, ≥ 30 kg/m(2); n = 19) and nonobese (BMI, 18.5-29.9 kg/m(2); n = 26). To determine clinical characteristics, body composition, bone mineral density, and maximal exercise testing was performed, and a 3-day dietary record was estimated. To assess quadriceps function, isokinetic exercise testing at 60° per second (quadriceps strength) and at 300° per second (quadriceps fatigue) was performed.. The absolute value of the peak torque was not significantly different between the groups; however, when the data were normalized by body mass and lean mass, significantly lower values were observed for obese women compared with those in the nonobese group (128% ± 25% vs 155% ± 24% and 224% ± 38% vs 257% ± 47%, P < 0.05). The fatigue index did not show any significant difference for either group; however, when the data were normalized by the body mass and lean mass, significantly lower values were observed for obese women (69% ± 16% vs 93% ± 18% and 120% ± 25% vs. 135% ± 23%, P < 0.01).. Our results show that despite reduced muscle force, the combination of obesity and postmenopause may be associated with greater resistance to muscle fatigue.

Topics: Body Composition; Body Mass Index; Bone Density; Diet; Exercise Test; Female; Humans; Middle Aged; Muscle Fatigue; Muscle Strength; Obesity; Physical Endurance; Postmenopause; Quadriceps Muscle; Torque; Weight-Bearing

despite evidence of an obesity-related disability, there is a lack of objective muscle functional data in overweight subjects. Only few studies provide instrumental strength measurements in non-syndromal obesity, whereas no data about Prader-Willi syndrome (PWS) are reported. The aim of our study was to characterize the lower limb muscle function of patients affected by PWS as compared to non-syndromal obesity and normal-weight subjects.. We enrolled 20 obese (O) females (age: 29.1 +/- 6.5 years; BMI: 38.1 +/- 3.1), 6 PWS females (age: 27.2 +/- 4.9 years; BMI: 45.8 +/- 4.4) and 14 healthy normal-weight (H) females (age: 30.1 +/- 4.7 years; BMI: 21 +/- 1.6). Isokinetic strength during knee flexion and extension in both lower limbs at the fixed angular velocities of 60 degrees /s, 180 degrees /s, 240 degrees /s was measured with a Cybex Norm dynamometer.. the H, O and PWS populations appear to be clearly stratified with regard to muscle strength.: PWS showed the lowest absolute peak torque (PT) for knee flexor and extensor muscles as compared to O (-55%) and H (-47%) (P = 0.00001). O showed significantly higher strength values than H as regard to knee extension only (P = 0.0014). When strength data were normalised by body weight, PWS showed a 50% and a 70% reduction in PT as compared to O and H, respectively. Knee flexors strength values were on average half of those reported for extension in all of the three populations.. the novel aspect of our study is the determination of objective measures of muscle strength in PWS and the comparison with O and H patients. The objective characterization of muscle function performed in this study provides baseline and outcome measures that may quantify specific strength deficits amendable with tailored rehabilitation programs and monitor effectiveness of treatments.

Topics: Adult; Causality; Exercise Therapy; Exercise Tolerance; Female; Gait Disorders, Neurologic; Humans; Knee; Movement; Muscle Strength; Muscle Weakness; Muscle, Skeletal; Obesity; Physical Fitness; Prader-Willi Syndrome; Quadriceps Muscle; Range of Motion, Articular; Resistance Training; Torque; Young Adult

Obesity is associated with an increased risk of falls and injury. Weight loss and strength training can be beneficial to balance, but knowing which is more beneficial would lead to interventions designed for maximal benefit in balance.. The goal of this study was to investigate the relative effects of weight loss and strength training on balance recovery using an ankle strategy.. We used a combination of experimental testing and forward dynamic simulations. Nine male subjects (body mass index = 30.1-36.9 kg x m(-2)) were released from a forward lean and attempted to recover balance using an ankle strategy. Lean angle was increased until subjects required a step or hip flexion to recover balance. The maximum lean angle, thetamax, was used as the measure of balance recovery capability. Experimental data served as inputs to an inverted pendulum model of balance recovery. Multiple simulations were performed to determine the effects of weight and strength on thetamax.. Both strength training and weight loss increased thetamax. Comparing the percent changes in weight and strength required to increase thetamax, a targeted amount revealed differences in intervention potency. For example, to increase thetamax by 1 degree, an 8.6 +/- 0.8% decrease in weight or 15.3 +/- 1.1% increase in strength was required. The differences in efficacy between the interventions became more apparent as larger increases in thetamax were targeted.. Balance recovery can improve with weight loss or strength gain, but a smaller amount of weight loss is needed than strength gain for a targeted improvement in balance recovery. This suggests that weight loss is a more potent intervention than strength training in improving balance recovery using an ankle strategy.

Topics: Accidental Falls; Adult; Analysis of Variance; Ankle; Body Mass Index; Electromyography; Humans; Male; Muscle Strength; Obesity; Postural Balance; Risk Factors; Torque; Virginia; Weight Loss

The present study aimed to compare quadriceps femoris muscle strength and fatigue between obese (grade II and III) and nonobese adults. Ten obese (mean age: 25 years; mean BMI: 41 kg/m(2)) and ten lean (mean age: 27 years; mean BMI: 23 kg/m(2)) men were tested. Quadriceps muscle fatigue was quantified as the (percent) torque loss during a voluntary isokinetic (50 maximal contractions at 180 degrees /s) and an electrostimulated (40 Hz) isometric protocol (5 min, 10% of the maximal torque). Maximal voluntary isometric and isokinetic torque and power were also measured. Voluntary torque loss was significantly higher (P < 0.05) in obese (-63.5%) than in lean subjects (-50.6%). Stimulated torque decreased significantly (P < 0.05) but equally in the two subject groups. Obese subjects displayed higher absolute (+20%; P < 0.01) but lower relative (i.e., normalized to body mass) (-32%; P < 0.001) muscle torque and power than their lean counterparts. Obese individuals demonstrated lower fatigue resistance during voluntary but not during stimulated knee extensions compared to their nonobese counterparts. Peripheral mechanisms of muscle fatigue -- at least those associated to the present stimulated test -- were not influenced by obesity. The observed quadriceps muscle function impairments (voluntary fatigue and relative strength) probably contribute to the reduced functional capacity of obese subjects during daily living activities.

Topics: Adult; Body Mass Index; Electric Stimulation; Humans; Isometric Contraction; Isotonic Contraction; Male; Matched-Pair Analysis; Muscle Fatigue; Muscle Strength; Obesity; Physical Endurance; Quadriceps Muscle; Torque

Topics: Adult; Gait; Humans; Knee Joint; Obesity; Osteoarthritis, Knee; Torque; Walking

While it is widely speculated that obesity causes increased loads on the knee leading to joint degeneration, this concept is untested. The purpose of the study was to identify the effects of obesity on lower extremity joint kinetics and energetics during walking. Twenty-one obese adults were tested at self-selected (1.29m/s) and standard speeds (1.50m/s) and 18 lean adults were tested at the standard speed. Motion analysis and force platform data were combined to calculate joint torques and powers during the stance phase of walking. Obese participants were more erect with 12% less knee flexion and 11% more ankle plantarflexion in self-selected compared to standard speeds (both p<0.02). Obese participants were still more erect than lean adults with approximately 6 degrees more extension at all joints (p<0.05, for each joint) at the standard speed. Knee and ankle torques were 17% and 11% higher (p<0.034 and p<0.041) and negative knee work and positive ankle work were 68% and 11% higher (p<0.000 and p<0.048) in obese participants at the standard speed compared to the slower speed. Joint torques and powers were statistically identical at the hip and knee but were 88% and 61% higher (both p<0.000) at the ankle in obese compared to lean participants at the standard speed. Obese participants used altered gait biomechanics and despite their greater weight, they had less knee torque and power at their self-selected walking speed and equal knee torque and power while walking at the same speed as lean individuals. We propose that the ability to reorganize neuromuscular function during gait may enable some obese individuals to maintain skeletal health of the knee joint and this ability may also be a more accurate risk indicator for knee osteoarthritis than body weight.

Topics: Adult; Ankle Joint; Biomechanical Phenomena; Case-Control Studies; Female; Gait; Hip Joint; Humans; Kinetics; Knee Joint; Male; Obesity; Time Factors; Torque; Walking

Cross-sectional study of isokinetic trunk and knee muscle strength in women who are obese.. To provide reference values, to identify variables that affect peripheral muscle strength, and to provide recommendations for isokinetic testing of trunk and knee muscles in women who are obese and morbidly obese.. The assessment of peripheral muscle strength is useful for the quantification of possible loss of strength, for exercise prescription, and for the evaluation of the effect of training programs in obese individuals.. Isokinetic trunk and leg muscle strength was assessed in 241 women who were obese (18-65 years, body mass index (BMI) > or = 30 kg/m2). Trunk flexion and extension peak torque (PT) was measured using the Cybex TEF dynamometer; trunk rotation (TR) PT was measured using the Cybex TORSO dynamometer; and knee flexion/extension (KFE) PT was measured using the Cybex 350 dynamometer. Body composition was assessed using the bioelectrical impedance method; physical activity was assessed using the Baecke questionnaire; and peak VO2 was assessed using an incremental exercise capacity test on a bicycle ergometer. To identify variables related to muscle strength, Pearson correlations were computed and a stepwise multiple regression analysis was performed.. Pearson correlation coefficients of all strength measurements at 60 degrees/s revealed low-to-moderate negative associations with age and positive associations with mass, height, fat free mass (FFM), and peak VO2 (P < 0.05), except for gravity-uncorrected trunk extension strength, which was not related to mass. The sports index of the Baecke questionnaire was associated with TR PT (r = 0.20, P < 0.01) and KFE PT (r = 0.18, P < 0.05).. The weight of the trunk accounts largely for the measured trunk extensor and flexor strength in women who are obese. Contributing variables of isokinetic trunk flexion and extension strength in women who are obese are age, height, and FFM; whereas sports activities and aerobic fitness are contributing factors for trunk rotational and knee extension strength. Recommendations for measuring isokinetic muscle strength in individuals who are obese are provided.

Topics: Adult; Aged; Body Composition; Body Mass Index; Cross-Sectional Studies; Exercise Test; Female; Humans; Knee; Middle Aged; Muscle, Skeletal; Obesity; Oxygen Consumption; Reference Values; Regression Analysis; Risk Factors; Rotation; Surveys and Questionnaires; Thorax; Torque

Recent epidemiological studies report that obesity is positively related to fracture incidence. In the present experiment, a model of postural control was used to examine the impact of an abnormal distribution of body fat in the abdominal area upon postural stability. Obese and lightweight humanoids were destabilized by imposing a small initial angular speed from a neutral standing position. To avoid a loss of stability yielding a stepping reaction or a fall, an ankle torque is necessary to counteract the perturbation. Three torque parameters--ankle torque onset, time to peak torque, and muscular ankle torque--were entered in a program to simulate the intrinsic variability of the human postural control system. A loss of stability was detected when the center of pressure exceeded stability margins. The most striking observation is the nonlinear increase of torque needed to stabilize the humanoid when the motor response was characterized by delayed temporal parameters. The effect was more pronounced when an anterior position of the center of mass was included in the simulations. This suggests that, when submitted to daily postural stresses and perturbations, obese persons (particularly those with an abnormal distribution of body fat in the abdominal area) may be at higher risk of falling than lightweight individuals.

Topics: Abdomen; Accidental Falls; Adipose Tissue; Models, Theoretical; Obesity; Posture; Risk Assessment; Torque