Lower Leg Lean Mass Research Articles

Body Composition, Falls, and Freezing of Gait in Parkinson's Disease: Gender-Specific Effects.

Postural instability and gait difficulties (PIGD) are a significant cause of mobility loss and lower quality of life in Parkinson's disease (PD). When PD progresses, patients may experience falls and freezing of gait (FoG) resulting in fear of falling and increasing sedentariness. Sedentary behavior results in sarcopenia associated with other changes in body composition, especially in older patients becoming frail. Previous studies have shown gender-specific changes in body composition with aging as well as gender disparities in symptoms and progression of PD, yet the association between gender-specific body composition and PIGD symptoms such as FoG along with falls, remains unexplored. This study aimed to investigate the association between gender-specific changes in body composition, FoG and falls assessment. 136 PD subjects underwent detailed clinical test batteries and had whole-body composition assessed using dual-energy X-ray absorptiometry (DXA). Multivariate logistic forward stepwise regression was performed to define body composition associations for FoG and falls. Multivariate regression analysis revealed that in males with PD, lower leg lean mass was significantly associated with the presence of FoG (OR, 0.429; 95% CI, 0.219-0.839; p=0.013) but not with falls. In females with PD, higher leg adipose mass was significantly associated with falls (OR, 4.780; 95% CI, 1.506-15.174; p=0.008) but not with FoG. These observations suggest gender specific associations between body composition and FoG vs. falls in PD. Future research should explore the impact of interventions on body composition in individuals with PD by paying specific attention to gender differences.

Higher thyroid hormone has a negative association with lower limb lean body mass in euthyroid older adults: Analysis from the Baltimore Longitudinal study of aging.

Background: Hyperthyroidism is associated with lower lean body mass, as a result of catabolic actions of thyroid hormone. Therefore, higher thyroid hormone levels could be a factor in the development of sarcopenia and age associated functional decline. The relationship between thyroid hormone and muscle mass in ambulatory, euthyroid older adults is not known. Method: We used mixed-effects models to estimate the cross-sectional relationships (accounting for inter-person variability) between thyroid axis hormone measures and lower limb composition or sarcopenia at visits in the Baltimore Longitudinal Study of Aging (BLSA) at which DEXA scans were available and both thyrotropin (TSH) and free thyroxine (FT4) were in the reference range. Analyses were adjusted for levothyroxine use, age, race, sex, BMI, smoking, alcohol intake, cholesterol, and systolic blood pressure. Results: 1442 euthyroid participants (median age 68, 50% female, and 69% white) contributed to 5306 visits from 2003 to 2019. FT4 was negatively associated with lower limb lean mass (beta: 88.49; 95% Confidence Interval (CI): 122.78, -54.20; p < 0.001) and positively associated with sarcopenia (OR: 1.11%, 95% CI: 1.01, 1.22) in the whole cohort. Additionally, higher FT4 was associated with lower leg lean mass (beta: 66.79; 95% CI: 102.24, -31.33; p < 0.001) and sarcopenia (OR:1.09%, 95% CI:1.01, 1.18) in older adults, but not in younger adults alone. Conclusion: In euthyroid older adults, higher FT4 is associated with lower leg lean mass and higher odds of sarcopenia. Understanding the relationship between thyroid hormone and sarcopenia is needed to improve clinical decision-making and avoid functional decline from excess thyroid hormone use in older adults.

Poster 124: Intrinsic Anthropometric Factors are Associated with Bone Stress Injuries in Collegiate Distance Runners: New Risk Metrics &amp; Screening Tools?

Poster 124: Intrinsic Anthropometric Factors are Associated with Bone Stress Injuries in Collegiate Distance Runners: New Risk Metrics &amp; Screening Tools?

Anthropometric Factors Associated With Bone Stress Injuries in Collegiate Distance Runners: New Risk Metrics and Screening Tools?

Background:Lower limb bone stress injury (BSI) of the pelvis, femur, and tibia is prevalent in collegiate track and field distance runners. Bone mineral density (BMD), body composition (BComp), and anthropometric parameters before initial collegiate injury have not been compared between runners with BSI and their noninjured counterparts.Purpose:To characterize bone health in relation to BComp and anthropometric measurements from total-body dual x-ray absorptiometry (DXA) scans in collegiate male and female distance runners before BSI and develop BMD prediction models.Study Design:Case-control study; Level of evidence, 3.Methods:Distance runners (N = 79) from a single university track and field team were retrospectively enrolled into this study. The runners completed a DXA scan during the fall season (August-November) and participated in sport activities before the scan. Three months after scanning, electronic medical records were reviewed for the occurrence of BSI. An independent-sample t test was used to compare BMD (total and regional [spine, pelvis, and legs]), BComp (% body fat, fat mass, and lean mass), and anthropometric measurements (shoulder width and leg, arm, and trunk length) between runners with versus without BSI (included subgroup analysis by sex). Multiple linear regression with stepwise removal was used to determine variables most predictive of BMD.Results:Of the 79 enrolled participants (42 male, 37 female), 18 runners (22.8%; 11 female, 7 male) sustained a lower limb BSI. Compared with the noninjured group, injured runners had lower total and regional BMD (P < .001 for all) and shorter leg and arm lengths (P < .05 for both), whereas injured male runners had lower fat mass and injured female runners had lower lean mass in the legs (P < .05 for both). Injured runners’ age-matched total BMD Z score (-0.1 ± 0.6) was considered clinically normal. BComp and anthropometric measures were predictive of total and regional BMD (P < .05; R 2 = 0.64-0.80; percentage error = 3.8%-4.8%).Conclusion:The DXA scans of injured runners prior to incidence indicated lower BMD compared with noninjured runners. Shorter limb lengths, lower fat mass (male), and lower leg lean mass (female) may also be indicative of risk. Certain BComp and anthropometric measures were predictive of BMD.

Bone mineral density in patients with single ventricle

The accrual of bone mineral density (BMD) during childhood and adolescence is important because once peak BMD is achieved in early adulthood it declines from there. If peak BMD is low, then osteoporosis, fractures, and possibly other adverse outcomes can occur. The accrual of peak BMD is multifactorial, but there have been concerns that children with chronic disease, especially those with slow accrual of physical activity, are at risk for low BMD and, ultimately, low peak BMD. In this volume of The Journal, Vaikunth et al report on the results of a study of patients with single ventricle and Fontan physiology who underwent dual energy x-ray absorptiometry (DXA). They also evaluated leg lean mass as a measure of skeletal muscle. They excluded patients with Fontan baffle obstruction, moderate to severe kidney or liver disease, and patients with protein losing enteropathy. They found low BMD in both cortical and trabecular bone. Lower leg lean mass was associated with lower BMD. These results highlight that DXA, which is widely available in the clinical setting, is useful in the evaluation of BMD in these patients. The results in this study may be seen as a best-case scenario as patients with complications following their Fontan procedure were excluded. Finally, the lower leg lean mass indicates that diminished physical activity may be an important factor, suggesting possible interventions that could improve BMD during childhood and peak BMD in young adulthood. Article page 202 ▸ Deficits in the Functional Muscle–Bone Unit in Youths with Fontan PhysiologyThe Journal of PediatricsVol. 238PreviewTo determine whether dual energy X-ray absorptiometry (DXA), a clinically available tool, mirrors the magnitude of deficits in trabecular and cortical bone mineral density (BMD) demonstrated on peripheral quantitative computed tomography in youth with Fontan physiology. Full-Text PDF

Sex-differences In Exercising Hemodynamics: Role Of Exercising Muscle Mass

Sex-differences in O2 transport include O2 content (CaO2) and quantity of muscle mass. PURPOSE: To determine their consequences on exercising hemodynamics with large (e.g., 2-leg cycling (BIKE)) vs. small (e.g., 1-leg knee extension (KE)) muscle mass. METHODS: Healthy young subjects (4M, 3W) completed BIKE and KE exercise tests. The femoral artery and vein were catheterized to measure leg blood flow (Q), CaO2, and mean arterial pressure (MAP). Vascular conductance (VC), O2 delivery, and leg O2 uptake (VO2) were calculated. Measures were normalized to the right leg (BIKE) or quadriceps (KE) lean mass. Whole body VO2 was measured with a metabolic cart. Men and women were compared at similar and maximal work rates. RESULTS: Body mass was greater in men (M: 80±6 vs. W: 59±12 kg, p=0.03). Although quadriceps mass (3.3±0.2 vs. 2.0±0.3 kg, p<0.001) and CaO2 were lower, women had a higher mass-specific Q, VC (p=0.054), O2 delivery, and leg VO2 to maintain whole body VO2 during similar KE (Table 1). These differences were maintained during maximal KE, at which women tended to achieve a higher mass-specific work rate (21±2 vs. 25±3 W·kg-1, p=0.10). They were also apparent during similar BIKE despite a lower leg lean mass in women (8.7±0.3 vs. 5.3±0.7 kg, p<0.001). However, the differences were no longer present during maximal BIKE when mass-specific work rate was similar (21±2 vs. 20±2 W·kg-1, p=0.70) and whole body VO2 was lower in women. CONCLUSION: These findings highlight a greater hemodynamic capacity for women to overcome differences in CaO2 and maintain whole body VO2 at similar work rates during exercise. They also implicate the quantity of exercising muscle in facilitating the greater hemodynamic capacity and mass-specific work rate during maximal exercise with a small but not large muscle mass. Support: The Swedish National Centre for Research in Sports, Ministerio de Educacion y Ciencia of Spain, Dr. Manuel Morales Foundation, NSERCTable 1: Exercising hemodynamics (*p<0.05, **p<0.01, ***p<0.001 men vs. women)

Lower Leg Lean Mass Is Associated With Reduced Pulse Pressure Amplification In Postmenopausal Women

Sarcopenia, the age-related loss of skeletal muscle mass, has been associated with increased arterial stiffness (pulse wave velocity, PWV). Lower leg muscle mass has been associated with increased brachial-ankle PWV (baPWV), a measure of systemic arterial stiffness. Pulse pressure (PP) is lower in the aorta compared to the brachial artery (PP amplification, PPA), in healthy individuals. PPA decreases with aging due to increased aortic stiffening. Lower PPA is an independent predictor of cardiovascular death. It is unknown whether leg muscle mass is associated with lower PPA in postmenopausal women. PURPOSE: To examine relationships between leg lean mass (LegLM), PPA, and baPWV in postmenopausal women. METHODS: 93 postmenopausal women (aged 48 - 71 years; BMI: 30 ± 7) underwent vascular function and body composition testing. Aortic PP was determined using applanation tonometry. baPWV and brachial PP were measured using an oscillometric device with cuffs placed on the arms and ankles. LegLM was measured by dual-energy x-ray absorptiometry. Handgrip strength was measured as the maximal voluntary contraction (MVC). The relationships between these variables were analyzed using Pearson’s correlations. Significant correlations were subsequently analyzed using multiple linear regression. RESULTS: LegLM was correlated with baPWV (r = -.218, p = .034) and PPA (r = .298, p = .004). PPA was also negatively correlated with baPWV (r = -.261, p =.01). LegLM was positively associated with PPA (β = 0.216, t = 2.320, p = .023) after adjusting for age, MVC, systolic pressure, and heart rate. CONCLUSIONS: Low leg lean mass was related to vascular dysfunction measured as increased systemic arterial stiffness and reduced PPA. Greater muscle mass in the legs may be protective against increased systemic arterial stiffness and reduced PPA associated with aging.

Leg muscle activation patterns during walking and leg lean mass are different in children with and without developmental coordination disorder

BackgroundPrevious studies have shown that children with developmental coordination disorder (DCD) have a higher body fat and greater gait variability. Little research has investigated the gait muscle activity and lean mass measures in children with DCD. AimsTo compare the leg muscle activation patterns of the gait cycle and leg lean mass between children with and without DCD. MethodsFifty-one children were in the DCD group (38 males and 13 females; 7.95 ± 1.04 years) and fifty-two in the control group (34 males and 18 females; 8.02 ± 1.00 years). Peak muscle activation patterns of treadmill walking in the right leg for the eight-gait phases were measured by means of surface electromyography, an electrogoniometer, and foot contact switches. Leg lean mass measures were evaluated using a whole-body dual energy X-ray absorptiometry scan. ResultsChildren with DCD had a lower leg lean mass and appendicular lean mass index compared to the control group. Furthermore, they exhibited a less-pronounced peak muscle activation during the heel strike (gastrocnemius medialis), early swing (biceps femoris) and late swing phases (gastrocnemius medialis) of gait. Conclusions and implicationsAlthough lower limb total mass was similar between groups, the DCD group displayed lower lean mass measures than controls. Furthermore, children with DCD illustrated a lower leg peak muscle activation during the heel strike, early swing and late swing phases of gait when walking on a treadmill. Our results emphasize the need to incorporate lower limb phasic muscle strengthening components into gait rehabilitation programs for children with DCD.

Obesity Appears to Be Associated With Altered Muscle Protein Synthetic and Breakdown Responses to Increased Nutrient Delivery in Older Men, but Not Reduced Muscle Mass or Contractile Function.

Obesity is increasing, yet despite the necessity of maintaining muscle mass and function with age, the effect of obesity on muscle protein turnover in older adults remains unknown. Eleven obese (BMI 31.9 ± 1.1 kg · m(-2)) and 15 healthy-weight (BMI 23.4 ± 0.3 kg · m(-2)) older men (55-75 years old) participated in a study that determined muscle protein synthesis (MPS) and leg protein breakdown (LPB) under postabsorptive (hypoinsulinemic-euglycemic clamp) and postprandial (hyperinsulinemic hyperaminoacidemic-euglycemic clamp) conditions. Obesity was associated with systemic inflammation, greater leg fat mass, and patterns of mRNA expression consistent with muscle deconditioning, whereas leg lean mass, strength, and work done during maximal exercise were no different. Under postabsorptive conditions, MPS and LPB were equivalent between groups, whereas insulin and amino acid administration increased MPS in only healthy-weight subjects and was associated with lower leg glucose disposal (LGD) (63%) in obese men. Blunting of MPS in the obese men was offset by an apparent decline in LPB, which was absent in healthy-weight subjects. Lower postprandial LGD in obese subjects and blunting of MPS responses to amino acids suggest that obesity in older adults is associated with diminished muscle metabolic quality. This does not, however, appear to be associated with lower leg lean mass or strength.

Adverse Fat Depots and Marrow Adiposity Are Associated With Skeletal Deficits and Insulin Resistance in Long-Term Survivors of Pediatric Hematopoietic Stem Cell Transplantation.

Allogeneic hematopoietic stem-cell transplantation (alloHSCT) survivors treated with total body irradiation (TBI) exhibit bone deficits and excess adiposity, potentially related to altered mesenchymal stem cell differentiation into osteoblasts or adipocytes. We examined associations among fat distribution, bone microarchitecture, and insulin resistance in alloHSCT survivors after TBI. This was a cross-sectional observational study of 25 alloHSCT survivors (aged 12 to 25 years) a median of 9.7 (4.3 to 19.3) years after alloHSCT compared to 25 age-, race-, and sex-matched healthy controls. Vertebral MR spectroscopic imaging and tibia micro-MRI were used to quantify marrow adipose tissue (MAT) and trabecular microarchitecture. Additional measures included DXA whole-body fat mass (WB-FM), leg lean mass (Leg-LM), trunk visceral adipose tissue (VAT), and CT calf muscle density. Insulin resistance in alloHSCT survivors was estimated by HOMA-IR. AlloHSCT survivors had lower Leg-LM (p < 0.001) and greater VAT (p < 0.01), MAT (p < 0.001), and fat infiltration of muscle (p = 0.04) independent of WB-FM, versus matched controls; BMI did not differ. Survivors had lower bone volume fraction and abnormal microarchitecture including greater erosion and more rod-like structure versus controls (all p = 0.04); 14 had vertebral deformities and two had compression fractures. Greater WB-FM, VAT, MAT, and muscle fat infiltration were associated with abnormal trabecular microarchitecture (p < 0.04 for all). AlloHSCT HOMA-IR was elevated, associated with younger age at transplantation (p < 0.01), and positively correlated with WB-FM and VAT (both p < 0.01). In conclusion, the markedly increased marrow adiposity, abnormal bone microarchitecture, and abnormal fat distribution highlight the risks of long-term treatment-related morbidity and mortality in alloHSCT recipients after TBI. Trabecular deterioration was associated with marrow and visceral adiposity. Furthermore, long-term survivors demonstrated sarcopenic obesity, insulin resistance, and vertebral deformities. Future studies are needed to identify strategies to prevent and treat metabolic and skeletal complications in this growing population of childhood alloHSCT survivors.

Increased ceramide content and NFκB signaling may contribute to the attenuation of anabolic signaling after resistance exercise in aged males

One of the most fundamental adaptive physiological events is the response of skeletal muscle to high-intensity resistance exercise, resulting in increased protein synthesis and ultimately larger muscle mass. However, muscle growth in response to contraction is attenuated in older humans. Impaired contractile-induced muscle growth may contribute to sarcopenia: the age-associated loss of muscle mass and function that is manifested by loss of strength, contractile capacity, and endurance. We hypothesized that the storage of ceramide would be increased in older individuals and this would be associated with increases in NFκB signaling and a decreased anabolic response to exercise. To test this hypothesis we measured ceramides at rest and anabolic and NFκB signaling after an acute bout of high-intensity resistance exercise in young and older males. Using lipidomics analysis we show there was a 156% increase in the accumulation of C16:0-ceramide (P < 0.05) and a 30% increase in C20:0-ceramide (P < 0.05) in skeletal muscle with aging, although there was no observable difference in total ceramide. C16:0-ceramide content was negatively correlated (P = 0.008) with lower leg lean mass. Aging was associated with a ~60% increase in the phosphorylation of the proinflammatory transcription factor NFκB in the total and nuclear cell fractions (P < 0.05). Furthermore, there was an attenuated activation of anabolic signaling molecules such as Akt (P < 0.05), FOXO1 (P < 0.05), and S6K1 (P < 0.05) after an acute bout of high-intensity resistance exercise in older males. We conclude that ceramide may have a significant role in the attenuation of contractile-induced skeletal muscle adaptations and atrophy that is observed with aging.

Evaluation of the strength-size relationship in vivo using various muscle size indices.

It is well accepted that maximum strength is related to muscle size. The primary purpose of this study was to determine whether anthropometric or dual-energy x-ray absorptiometry (DEXA) estimates of muscle size were valid predictors of plantar flexor maximum voluntary contraction (MVC) strength and could be used in lieu of more sophisticated techniques (e.g., magnetic resonance imaging (MRI)). Additionally, we compared the relationship among MVC and three MRI-determined muscle size measures; anatomical (ACSA) and physiological (PCSA) cross-sectional areas; and muscle volume (VOLm). We measured plantar flexor MVC at 1.83 rad and various indices of muscle size: 1) body weight, 2) total body lean mass (LM) (DEXA), 3) lower leg LM (DEXA), 4) lower leg circumference, 5) estimated muscle+bone cross-sectional area (CSA) from circumference and calf skin-fold, 6) triceps surae ACSA, 7) triceps surae PCSA, and (8) triceps surae volume (VOLm), in 39 premenopausal women (mean +/- SD: 36 +/- 8 yr, 165 +/- 6 cm, and 65 +/- 9 kg). Zero-order correlations showed significant (P < 0.05) associations between MVC and total body LM (r = 0.365), lower leg LM (r = 0.381), circumference (r = 0.584), estimated muscle+bone CSA (r = 0.447), ACSA (r = 0.733), PCSA (r = 0.715), and VOLm (r = 0.649). By using the Fisher Z-transformation, ACSA and PCSA correlated significantly higher with MVC (P < 0.05) than anthropometric and DEXA indices. Further, only ACSA and PCSA regressed to the origin, indicating the ability to predict MVC was greatest with these two measures. The MRI-determined muscle size indices, which were specific to the triceps surae, correlated with strength better than whole limb anthropometric and DEXA indices. In this group of women, both ACSA and PCSA appeared superior to VOLm for predicting strength. PCSA was not found to be more precise than ACSA. ACSA appears to provide adequate precision for estimating plantar flexor specific tension in vivo.