Neural control of blood pressure is altered following isolated leg heating in aged humans.

There is a sustained reduction in arterial blood pressure that occurs in aged adults following exposure to acute leg heating. We tested the hypothesis that acute leg heating would decrease arterial blood pressure in aged adults secondary to sympathoinhibition. We exposed 13 young and 10 aged adults to 45 min of leg heating. Muscle sympathetic nerve activity (radial nerve) was measured before leg heating (preheat) and 30 min after (recovery) and is expressed as burst frequency. Neurovascular transduction was examined by assessing the slope of the relation between muscle sympathetic nerve activity and leg vascular conductance measured at rest and during isometric handgrip exercise performed to fatigue. Arterial blood pressure was well maintained in young adults (preheat, 86 ± 6 mmHg vs. recovery, 88 ± 7 mmHg; P = 0.4) due to increased sympathetic nerve activity (preheat, 16 ± 7 bursts/min vs. recovery, 22 ± 10 bursts/min; P < 0.01). However, in aged adults, sympathetic nerve activity did not differ from preheat (37 ± 5 bursts/min) to recovery (33 ± 6 bursts/min, P = 0.1), despite a marked reduction in arterial blood pressure (preheat, 101 ± 7 mmHg vs. recovery, 94 ± 6 mmHg; P < 0.01). Neurovascular transduction did not differ from preheat to recovery for either age group (P ≥ 0.1). The reduction in arterial blood pressure that occurs in aged adults following exposure to acute leg heating is mediated, in part, by a sympathoinhibitory effect that alters the compensatory neural response to hypotension.NEW & NOTEWORTHY There is a sustained reduction in arterial blood pressure that occurs in aged adults following exposure to acute leg heating. However, the neurovascular mechanisms mediating this response remain unknown. Our findings demonstrate for the first time that this reduction in arterial blood pressure is mediated, in part, by a sympathoinhibitory effect that alters the compensatory neural response to hypotension in aged adults.

Plasticity in the growth of body segments in relation to height-for-age and maternal education in Guatemala.

OBJECTIVES: Plasticity in the growth of body segments between populations has been researched in relation to migration, temporal change and high-altitude studies. We study the within population variation in body segments, thus controlling for some of the environmental and genetic differences that could be at play in between populations studies. We test a version of the thrifty phenotype hypothesis, where the growth of head-trunk and hand are prioritized due to their functional significance over height and leg growth. MATERIALS AND METHODS: A total of 3913 Guatemalan, rural, semi-urban and urban, Maya and Ladino children 6 to 15 years old were studied. Height, sitting height, leg length, and metacarpal length were studied in relation to three proxies for living conditions: height- and leg length-for-age, and maternal education. Estimation statistics and null hypothesis significance testing were used to analyze the data. RESULTS: Metatarsal length and sitting height values were higher than height and leg length respectively. Relative metacarpal length was conserved across height-for-age groups. Females were less affected than males for metacarpal length and sitting height, but more affected for leg length. CONCLUSION: Our results agree with the thrifty phenotype hypothesis, where metacarpal and sitting height growth would be prioritized over height and leg length due to greater functional significance.

Body proportionality and adiposity are not related in 6- to 8-year-old Yucatec Maya children.

OBJECTIVE: The aim of this study was to analyze the association between relative leg length (RLL) (leg length × 100/height) and adiposity in a sample of 6- to 8-year-old children of Maya ancestry from Motul and Merida, Mexico. METHODS: This cross-sectional study included 260 children (128 girls) measured between 2011 and 2015. The RLL was used as a measure of body proportionality. Linear regression models were performed to examine the association between RLL (predictor) and three adiposity indicators (outcome variables): fat mass index (kg/m2 ), waist circumference (z-score), and sum of triceps and subscapular skinfolds (z-score). RESULTS: The prevalence of stunting was 12%, and a higher prevalence (19%) of short RLL (leg stunting) was found. The prevalence of overweight and obesity were 16% and 20%, respectively, but the highest prevalence was found for abdominal obesity (40%). None of the adiposity indicators were related to RLL (P > .05), even after adjusting for the influence of children's sex and age. CONCLUSIONS: Our results suggest that the coexistence of short RLL and high body adiposity is not observed in all populations. Our findings do not discount the possibility that a negative association between RLL and adiposity is expressed at older ages.

Sex-dependent effect of post-migration adaptation on height and relative lower leg length in Polish youth.

BACKGROUND: Growth in tibia length is considered to be particularly sensitive to environmental stress. AIM: To estimate the effect of parental migration status on the relative length of the tibia in their school-age children. SUBJECTS AND METHODS: Data included a nationwide random sample of 17,155 schoolchildren, 7-18 years of age, examined between 1966 and 1969 in Poland who provided information on anthropometric measurements and demographic and social characteristics. Parental migration status was based on paternal migration history. After standardisation by LMS method, z-scores of relative tibia length and z-scores of height were used for analysis. Three-way ANOVA was used to evaluate the influence of migration on tibia length-to-height ratio. RESULTS: Sons of migrants have a significantly higher tibia length-to-height ratio compared to sons of non-migrants. Children of non-migrants were taller than children of migrants among boys in medium SES and among girls in high and low SES. Relative tibia length indicated significant effects of migration among boys in all age categories and in late adolescent girls: sons of migrants had a higher ratio and daughters of migrants had a lower tibia length-to-height ratio. CONCLUSION: It is possible that migration experiences of the parents may have influenced the growth of their offspring. The results emphasise the potential importance of research addressing the impact of different types of migration on growth of children.

Motor unit activity, force steadiness, and perceived fatigability are correlated with mobility in older adults.

The purpose of our study was to examine the associations between the performance of older adults on four tests of mobility and the physical capabilities of the lower leg muscles. The assessments included measures of muscle strength, muscle activation, and perceived fatigability. Muscle activation was quantified as the force fluctuations-a measure of force steadiness-and motor unit discharge characteristics of lower leg muscles during submaximal isometric contractions. Perceived fatigability was measured as the rating of perceived exertion achieved during a test of walking endurance. Twenty participants (73 ± 4 yr) completed one to four evaluation sessions that were separated by at least 3 wk. The protocol included a 400-m walk, a 10-m walk at maximal and preferred speeds, a chair-rise test, and the strength, force steadiness, and discharge characteristics of motor units detected by high-density electromyography of lower leg muscles. Multiple-regression analyses yielded statistically significant models that explained modest amounts of the variance in the four mobility tests. The variance explained by the regression models was 39% for 400-m walk time, 33% for maximal walk time, 42% for preferred walk time, and 27% for chair-rise time. The findings indicate that differences in mobility among healthy older adults were partially associated with the level of perceived fatigability (willingness of individuals to exert themselves) achieved during the test of walking endurance and the discharge characteristics of soleus, medial gastrocnemius, and tibialis anterior motor units during steady submaximal contractions with the plantar flexor and dorsiflexor muscles. NEW & NOTEWORTHY Differences among healthy older adults in walking endurance, walking speed, and ability to rise from a chair can be partially explained by the performance capabilities of lower leg muscles. Assessments comprised the willingness to exert effort (perceived fatigability) and the discharge times of action potentials by motor units in calf muscles during submaximal isometric contractions. These findings indicate that the nervous system contributes significantly to differences in mobility among healthy older adults.

The motor repertoire of older adult fallers may constrain their response to balance perturbations.

Older adults are at a high risk of falls, and most falls occur during locomotor activities like walking. This study aimed to improve our understanding of changes in neuromuscular control associated with increased risk of falls in older adults in the presence of dynamic balance challenges during walking. Motor module (also known as muscle synergy) analyses identified changes in the neuromuscular recruitment of leg muscles during walking with and without perturbations designed to elicit the visual perception of lateral instability. During normal walking we found that a history of falls (but not age) was associated with reduced motor module complexity and that age (but not a history of falls) was associated with increased step-to-step variability of module recruitment timing. Furthermore, motor module complexity was unaltered in the presence of optical flow perturbations. The specific effects of a history of falls on leg muscle recruitment included an absence and/or inability to independently recruit motor modules normally recruited to perform biomechanical functions important for walking balance control. These results suggest that fallers do not recruit the appropriate motor modules necessary for well-coordinated walking balance control even in the presence of perturbations. The identified changes in the modular control of walking balance in older fallers may either represent a neural deficit that leads to poor balance control or a prior history of falls that results in a compensatory motor adaptation. In either case, our study provides initial evidence that a reduced motor repertoire in older adult fallers may be a constraint on their ability to appropriately respond to balance challenges during walking. NEW & NOTEWORTHY This is the first study to demonstrate a reduced motor repertoire during walking in older adults with a history of falls but without any overt neurological deficits. Furthermore, using virtual reality during walking to elicit the visual perception of lateral instability, we provide initial evidence that a reduced motor repertoire in older adult fallers may be a constraint on their ability to appropriately respond to balance challenges during walking.

Intergenerational changes in limb circumferences in children and adolescents aged 3-18 from Kraków (Poland) from 1983 to 2010.

OBJECTIVES: Measurements of body circumferences are often used in anthropology. The research on this topic, however, rarely concerns limb girths or secular trends. The main aim of this study was to investigate the occurrence of secular trends in selected limb circumferences among children and adolescents. METHODS: The research was based on measurements from two cross-sectional studies carried out in 1983 and 2010 with children and adolescents aged 3-18 from Krakow, Poland. The circumferences of the arm, forearm, thigh and calf, as well as the sum of circumferences and selected indicators, were analyzed. The series were compared using the two-way anova test. RESULTS: In most age groups of both sexes, a positive secular trend was observed for the majority of studied traits. The exception was the thigh circumference, for which, among girls, measurements in both series were similar, and negative intergenerational changes were recorded in the youngest age groups of both sexes as well as among the oldest girls. Most observed discrepancies were statistically significant in pre-school children and adolescents. CONCLUSIONS: The presence of positive secular trends shows that limb circumferences were increasing in subsequent generations, especially in boys. Contemporary girls, particularly in the older age groups, were more determined to have a slim figure and practiced conscious weight control. Summarizing, observed tendencies resulted from the improvement of socio-economic conditions, but were also related to the low level of physical activity.

Lack of age-specific influence on leg blood flow during incremental calf plantar-flexion exercise in men and women.

PURPOSE: Age-related exercising leg blood flow (LBF) responses during dynamic knee-extension exercise and forearm blood flow responses during handgrip exercise are preserved in normally active men but attenuated in activity-matched women. We explored whether these age- and sex-specific effects are also apparent during isometric calf plantar-flexion incremental exercise. METHODS: Normally active young men (YM, n = 15, 24 ± 2 years), young women (YW, n = 8, 22 ± 1 years), older men (OM, n = 13, 70 ± 7 years) and older women (OW, n = 10, 64 ± 7 years) were tested. LBF was measured between contractions using venous occlusion plethysmography. RESULTS: Peak force obtained was higher (P < 0.05) in men compared with women and in young compared with older individuals. However, peak LBF (YM; 971 ± 328 ml min-1, OM; 985 ± 504 ml min-1, YW; 844 ± 366 ml min-1, OW; 960 ± 244 ml min-1) and peak leg vascular conductance [LVC = LBF/(MAP + hydrostatic pressure)] responses (YM; 6.0 ± 1.8 ml min-1 mmHg-1, OM; 5.5 ± 2.8 ml min-1 mmHg-1, YW; 5.3 ± 2.1 ml min-1 mmHg-1, OW; 5.5 ± 1.6 ml min-1 mmHg-1) were similar among the four groups. Furthermore, the hyperaemic (YM; 8.8 ± 3.7 ml min-1 %Fpeak-1 OM; 8.3 ± 5.4 ml min-1 %Fpeak-1, YW; 8.2 ± 3.5 ml min-1 %Fpeak-1, OW; 9.6 ± 2.2 ml min-1 %Fpeak-1) and vasodilatory responses (YM; 0.053 ± 0.020 ml min-1 mmHg-1 %Fpeak-1, OM; 0.048 ± 0.028 ml min-1 mmHg-1 %Fpeak-1, YW; 0.051 ± 0.019 ml min-1 mmHg-1 %Fpeak-1, OW; 0.055 ± 0.014 ml min-1 mmHg-1 %Fpeak-1) were not different among the four groups. These results were accompanied by similar resting LBF responses among groups and were not affected when data were normalised to estimated leg muscle mass. CONCLUSIONS: Our results demonstrate that exercising LBF responses during isometric incremental calf muscle exercise are preserved in older men and women, suggesting that the previously observed age-related attenuations in leg and forearm hyperaemia among women may be muscle-group specific.

Knemometry is more sensitive to systemic effects of inhaled corticosteroids in children with asthma than 24-hour urine cortisol excretion.

BACKGROUND: Pharmacodynamic assessment of the systemic effect of inhaled corticosteroids (ICSs) is often done by measuring 24-hour urine free cortisol (UFC) excretion. Knemometry assessing short-term lower-leg growth rate (LLGR) is a more rarely used alternative. OBJECTIVE: The primary aim of this study was to compare the sensitivity of LLGR and 24-hour UFC excretion for evaluating systemic exposure to ICSs in prepubertal children with asthma. The secondary aim was to evaluate factors influencing the precision of LLGR calculated by the traditional 1 leg nonparametric method versus a new 2 leg parametric method. METHODS: The study evaluated 60 children with mild asthma aged 5 to 12 years participating in a randomized controlled trial of ICSs with longitudinal concomitant assessments of LLGR and 24-hour UFC excretion. The sensitivity of the safety assessments was analyzed by comparing LLGR and 24-hour UFC in the placebo run-in period with values in the ICS treatment period by using paired t tests. Factors with a potential influence on LLGR were analyzed by means of ANOVA and the Levene test of homogeneity. RESULTS: The mean LLGR was significantly reduced during the ICS versus placebo run-in periods: 0.18 mm/wk (SD, 0.55 mm/wk) versus 0.45 mm/wk (SD, 0.39 mm/wk), with a mean difference of 0.27 mm/wk (95% CI, 0.05-0.48 mm/wk; P = .02). In contrast, there was no difference in 24-hour UFC excretion: 6.91 nmol/mmol (SD, 4.67 nmol/mmol) versus 7.58 nmol/mmol (SD, 6.17 nmol/mmol), with a mean difference of 0.67 nmol/mmol (95% CI, -1.13 to 2.48 nmol/mmol; P = .46). We observed no significant difference in parametric determined LLGR caused by the child's age or sex, investigator, or season of measurement, whereas some differences were observed for the nonparametric LLGR. CONCLUSION: These findings suggest that knemometry is a more sensitive pharmacodynamic measure of systemic effects of ICSs than 24-hour UFC excretion and that a parametric determination of LLGR increases the sensitivity of the method. These findings should be considered by legislative authorities in the future.

Aesthetic Improvement of Undeveloped Calves After Treatment of Congenital Clubfoot Deformity.

BACKGROUND: Even when clubfoot deformity is treated in a timely manner, the consequences observed in adulthood include hypoplasia of the calf muscles, gait impairment, decreases in foot size, and it can also affect the tibial length. These consequences may have negative impacts on the patient's subjective appraisal of long-term outcomes, and can influence the patient's self-esteem in both male and female patients. OBJECTIVES: We present our experience in the treatment of undeveloped calves after surgical treatment of congenital clubfoot. METHODS: In total, 72 patients underwent corrective surgery in order to improve undeveloped calves resulting from a congenital clubfoot deformity. We used calf silicone implants in combination with fat grafting in multistaged procedures, in order to decrease complication rates and improve aesthetic outcome. RESULTS: Amongst our patients there were 54 (75%) females and 18 (25%) males. All of the patients, except one, had unilateral calf hypoplasia. The procedures were divided into several groups: (1) medial calf augmentation with silicone implants; (2) medial calf augmentation with silicone implants and fat grafting; and (3) medial and lateral calf augmentation with silicone implants and fat grafting. We had one case of a hyperpigmented scar and one case of partial scar dehiscence. There were no cases of compartment syndrome. The average follow-up period was 9.8 months. CONCLUSIONS: Calf enhancement surgery in patients with congenital clubfoot deformity is very gratifying. When combining calf implants with fat grafting in multistaged procedures, we can achieve excellent results with low complication rates.

Kidney transplantation fails to provide adequate growth in children with chronic kidney disease born small for gestational age.

BACKGROUND: Children with chronic kidney disease are frequently born small for gestational age (SGA) and prone to disproportionately short stature. It is unclear how SGA affects growth after kidney transplantation (KTx). METHODS: Linear growth (height, sitting height, and leg length) was prospectively investigated in a cohort of 322 pediatric KTx recipients, with a mean follow-up of 4.9 years. Sitting height index (ratio of sitting height to total body height) was used to assess body proportions. Predictors of growth outcome in KTx patients with (n = 94) and without (n = 228) an SGA history were evaluated by the use of linear mixed-effects models. RESULTS: Mean z-scores for all linear body dimensions were lower in SGA compared with non-SGA patients (p < 0.001). SGA patients presented with higher target height deficit and degree of body disproportion (p < 0.001). The latter was mainly due to reduced leg growth during childhood. Pubertal trunk growth was diminished in SGA patients, and the pubertal growth spurt of legs was delayed in both groups, resulting in further impairment of adult height, which was more frequently reduced in SGA than in non-SGA patients (50 % vs 18 %, p < 0.001). Use of growth hormone treatment in the pre-transplant period, preemptive KTx, transplant function, and control of metabolic acidosis were the only potentially modifiable correlates of post-transplant growth in SGA groups. By contrast, living related KTx, steroid exposure, and degree of anemia proved to be correlates in non-SGA only. CONCLUSIONS: In children born SGA, growth outcome after KTx is significantly more impaired and affected by different clinical parameters compared with non-SGA patients.

Leg Length Versus Torso Length in Pedophilia: Further Evidence of Atypical Physical Development Early in Life.

Adult men's height results from an interaction among positive and negative influences, including genetic predisposition, conditions in utero, and influences during early development such as nutritional quality, pathogen exposure, and socioeconomic status. Decreased height, reflected specifically as a decreased leg length, is strongly associated with increased risk of poorer health outcomes. Although prior research has repeatedly shown that pedophiles are shorter than nonpedophiles, the largest study to date relied on self-reported height. In the present study, pedophiles demonstrated reduced measured height and reduced leg length as compared with teleiophiles. Given the prenatal and early childhood origins of height, these findings contribute additional evidence to a biological, developmental origin of pedophilia. In addition, the magnitude of this height difference was substantially larger than that found in children exposed to a variety of early environmental stressors, but similar to that seen in other biologically based neurodevelopmental disorders.

Unexpected dependence of RyR1 splice variant expression in human lower limb muscles on fiber-type composition.

The skeletal muscle ryanodine receptor Ca(2+) release channel (RyR1), essential for excitation-contraction (EC) coupling, demonstrates a known developmentally regulated alternative splicing in the ASI region. We now find unexpectedly that the expression of the splice variants is closely related to fiber type in adult human lower limb muscles. We examined the distribution of myosin heavy chain isoforms and ASI splice variants in gluteus minimus, gluteus medius and vastus medialis from patients aged 45 to 85 years. There was a strong positive correlation between ASI(+)RyR1 and the percentage of type 2 fibers in the muscles (r = 0.725), and a correspondingly strong negative correlation between the percentages of ASI(+)RyR1 and percentage of type 1 fibers. When the type 2 fiber data were separated into type 2X and type 2A, the correlation with ASI(+)RyR1 was stronger in type 2X fibers (r = 0.781) than in type 2A fibers (r = 0.461). There was no significant correlation between age and either fiber-type composition or ASI(+)RyR1/ASI(-)RyR1 ratio. The results suggest that the reduced expression of ASI(-)RyR1 during development may reflect a reduction in type 1 fibers during development. Preferential expression of ASI(-) RyR1, having a higher gain of in Ca(2+) release during EC coupling than ASI(+)RyR1, may compensate for the reduced terminal cisternae volume, fewer junctional contacts and reduced charge movement in type 1 fibers.

Individual heterogeneity and offspring sex affect the growth-reproduction trade-off in a mammal with indeterminate growth.

Reproduction can lead to a trade-off with growth, particularly when individuals reproduce before completing body growth. Kangaroos have indeterminate growth and may always face this trade-off. We combined an experimental manipulation of reproductive effort and multi-year monitoring of a large sample size of marked individuals in two populations of eastern grey kangaroos to test the predictions (1) that reproduction decreases skeletal growth and mass gain and (2) that mass loss leads to reproductive failure. We also tested if sex-allocation strategies influenced these trade-offs. Experimental reproductive suppression revealed negative effects of reproduction on mass gain and leg growth from 1 year to the next. Unmanipulated females, however, showed a positive correlation between number of days lactating and leg growth over periods of 2 years and longer, suggesting that over the long term, reproductive costs were masked by individual heterogeneity in resource acquisition. Mass gain was necessary for reproductive success the subsequent year. Although mothers of daughters generally lost more mass than females nursing sons, mothers in poor condition experienced greater mass gain and arm growth if they had daughters than if they had sons. The strong links between individual mass changes and reproduction suggest that reproductive tactics are strongly resource-dependent.

The application of knemometry to measure childhood short-term growth among the indigenous Shuar of Ecuador.

OBJECTIVES: Knemometry, the precise measurement of lower leg (LL) length, suggests that childhood short-term (e.g., weekly) growth is a dynamic, nonlinear process. However, owing to the large size and complexity of the traditional knemometer device, previous study of short-term growth among children has been restricted predominantly to clinical settings in industrialized Western nations. The aim of the present study is to address this limitation and promote broader understandings of global variation in childhood development by: (1) describing a custom-built portable knemometer and assessing its performance in the field; and (2) demonstrating the potential application of such a device by characterizing childhood short-term LL growth among the indigenous Shuar of Amazonian Ecuador. MATERIALS AND METHODS: Mixed-longitudinal LL length data were collected weekly from 336 Shuar children age 5-12 years old using the custom portable knemometer (n = 1,145 total observations). Device performance and Shuar short-term LL growth were explored using linear mixed effects models and descriptive statistics. RESULTS: The portable knemometer performed well across a range of participant characteristics and possesses a low technical error of measurement of 0.18 mm. Shuar childhood LL growth averages 0.47 mm/week (SD = 0.75 mm/week), but exhibits large between- and within-individual variation. DISCUSSION: Knemometry can be reliably performed in the field, providing a means for evaluating childhood short-term growth among genetically and ecologically diverse populations. Preliminary findings suggest that Shuar weekly LL growth is comparable in mean magnitude but likely more variable than reported for healthy Western children. Future work will further explore these patterns. Am J Phys Anthropol 160:353-357, 2016. © 2016 Wiley Periodicals, Inc.

Sexual dimorphism in growth in the relative length of the forearm and relative knee height during adolescence.

There are numerous studies concerning sexual dimorphism in body proportions, but only a few have investigated growth in the relative length of particular segments of the upper and lower limbs during adolescence. The aim of the study is an assessment of sex differences of longitudinal growth in the relative length of the forearm and knee height among adolescents. Sample involved 121 boys and 111 girls, participants of the Wroclaw Growth Study, examined annually between 8 and 18 years of age. Sexual dimorphism in six ratios: forearm length and knee height relatively to: trunk, height, and limb length were analyzed using a two-way analysis of variance with repeated measurements. The sex and age relative to an estimate of maturity timing (3 years before, and after age class at peak height velocity [PHV]) were independent variables. All of the ratios showed significant sex differences in interaction with age relative to age at PHV. The relative length of the forearm, in boys, did not change significantly with the years relative to age at PHV, whereas in girls, was the lowest in the two first age classes and afterward significantly increased just 1 year before and during the adolescent growth spurt, remaining unchanged in further age classes. For relative knee height no clear pattern for sex differences was noticed. It is proposed that relatively longer forearms, particularly in relation to the trunk in girls, could have evolved as an adaptation to more efficient infant carrying and protection during breastfeeding.

Passive leg movement-induced vasodilation in women: the impact of age.

Passive leg movement (PLM), an assessment of predominantly nitric oxide-dependent vasodilation, is decreased with age and cannot be augmented by posture-induced increases in femoral perfusion pressure in older men. However, this novel method of assessing vascular function has yet to be used to evaluate alterations in nitric oxide-dependent vasodilation with age in females. PLM was performed in 10 young (20 ± 1 yr) and 10 old (73 ± 2 yr) women in both the supine and upright-seated postures, whereas central and peripheral hemodynamic measurements were acquired second by second using noninvasive techniques (finger photoplethysmography and Doppler ultrasound, respectively). The heart rate response to PLM was attenuated in the old compared with the young in both the supine (young, 10 ± 1; and old, 5 ± 1 beats/min; P < 0.05) and upright-seated posture (young, 10 ± 2; and old, 5 ± 1 beats/min; P < 0.05), leading to a blunted cardiac output response in the old in the upright-seated posture (young, 1.0 ± 0.2; and old, 0.3 ± 0.1 l/min; P < 0.05). The PLM-induced peak change in leg vascular conductance was lower in the old compared with the young in both postures (young supine, 5.7 ± 0.5; old supine, 2.6 ± 0.3; young upright, 9.2 ± 0.7; and old upright, 2.2 ± 0.4 ml·min(-1)·mmHg(-1); P < 0.05) and was significantly augmented by the upright-seated posture in the young only, revealing a vasodilatory reserve capacity in the young (3.5 ± 0.6 ml·min(-1)·mmHg(-1), P < 0.05) that was absent in the old (-0.5 ± 0.3 ml·min(-1)·mmHg(-1), P = 0.18). These data support previous literature demonstrating attenuated PLM-induced vasodilation with age and extend these findings to include the female population, thus bolstering the utility of PLM as a novel assessment of vascular function across the life span in humans.

Leg length and type 2 diabetes: what's the link?

PURPOSE OF REVIEW: Human leg length is determined by a complex interplay of genetics and environmental exposures during development, which may be associated with long-term metabolic disease risk. Here, we review recent literature on the link between relative leg length and type 2 diabetes in more and less economically developed societies, wherein the contextual influences on relative leg length are unique. We also hypothesize mechanisms underlying and mediating this association. RECENT FINDINGS: Evidence from more economically prosperous Western populations and contemporary adult populations in China and Brazil indicates that lower relative leg length is associated with greater risk for impaired glucose homeostasis and type 2 diabetes. In Brazil, this association was stronger among women with early menarche. Although still poorly defined and in need of further research, the potential mechanisms likely involve suboptimal early-life net nutrition that simultaneously leads to retarded growth and impaired glucose regulation. An untested hypothesis is that the association is mediated by differences in skeletal muscle mass. SUMMARY: Epidemiologic evidence from diverse settings points to humans with shorter legs relative to their stature having higher risk for type 2 diabetes. Although research is needed to test mechanistic hypotheses, the greatest potential for improving public health will come through identification of, and intervention upon, the upstream modifiable determinants of inadequate leg growth.

Is leg length a biomarker of early life conditions? Evidence from a historically short population.

OBJECTIVES: While one group (Positive Group) has argued that leg length is a more accurate biomarker of early life conditions than height, another group (Negative Group) has challenged this argument. Analyzing Indonesian data, we attempt to reconcile these contrasting arguments. METHODS: The sample consists of 4,193 men and 4,684 women, aged 40-70. We regress leg length, trunk length, and height each on education (a proxy for early life conditions), age, and ethnicity. We also adjust for hip size and shrinkage. RESULTS: The relationship is statistically significant for leg length, which is generally consistent with the assertion of the Positive Group. However, the relationship is smaller than that for height, which is generally consistent with that of the Negative Group. Specifically, an additional year of schooling is associated with a 0.080 cm longer leg length for men and 0.078 cm for women. The corresponding figures for height are 0.260 cm and 0.201 cm. This remains true when the magnitude of the relationship is compared with the mean length. CONCLUSIONS: Small sample sizes appear to drive the Negative Group's finding that leg length is not statistically significantly related to early life conditions. However, the magnitude of the relationship confirms the Negative Group's argument that leg length is not a more accurate biomarker of early life conditions than height.

[Disorder of the Longitudinal Limb Growth and Muscular Contractility].

BACKGROUND: The reduction of the muscular contractility in the patients after operative lengthening of the limb with delayed growth is the main factor limiting the volume of orthopaedic treatment. OBJECTIVE: Our aim was to study the dependence of the muscular contractility of the femur and tibia on their longitudinal sizes in healthy individuals and patients of various age and in the patients with different variants of natural growth disorders of one of the lower limb before and after its operative lengthening according to Ilizarov. METHODS: Maximal torque of various groups of the femoral and tibial muscles was evaluated in 78 patients aged from 4 to 40 years with delayed longitudinal growth from 3 to 12 cm of one of the lower limbs using original dynamometers. Control group included 424 healthy children aged from 7 to 15 years and 36 persons aged from 18 to 35 years. RESULTS: The dependence of maximal torque of various groups of the femoral and tibial muscles on their longitudinal sizes in healthy individuals and patients of various ages and gender as well as in the patients with growth disorders before and after their operative lengthening was presented. The affected limb muscular strength and the same of the intact one reduced every cm of the longitudinal growth delay (for instance, the posterior tibial muscle for 3.2 and 1.7 Nm correspondingly). CONCLUSION: Compensatory increase of the muscular strength in the contralateral femur was found only in significant reduction of the muscular contractility of the affected tibia. In equal amount of the tibial shortening its muscular strength reduced relatively more in the patients with congenital disease and consequences of the osteomyelitis and less in trauma cases.