Body composition as affected by physical activity and nutrition

Although exercise and/or training can augment maximum oxygen consumption, muscle strength, and endurance, it has not been shown to markedly increase lean body mass (LBM) or to markedly decrease body fat in humans unless androgens are given. Bed rest likewise leads to very modest changes in body composition. Over-nutrition, on the other hand, produces a significant increase in body LBM and fat, and undernutrition a fall in both; hence the evaluation of exercise programs should include assessment of energy intake.     

Promoting functional health in midlife and old age: long-term protective effects of control beliefs, social support, and physical exercise

Background

Previous studies have examined physical risk factors in relation to functional health, but less work has focused on the protective role of psychological and social factors. We examined the individual and joint protective contribution of control beliefs, social support and physical exercise to changes in functional health, beyond the influence of health status and physical risk factors in middle-aged and older adults. Given that functional health typically declines throughout adulthood, it is important to identify modifiable factors that can be implemented to maintain functioning, improve quality of life, and reduce disability.

Methodology/Principal Findings

We conducted a national longitudinal study, Midlife in the United States (MIDUS), with assessments in 1995–1996 and 2004–2006, and 3,626 community-residing adults, aged 32 to 84, were included in the analyses. Functional health (Physical Functioning subscale of the SF-36) and protective factors were measured at both occasions. While controlling for socio-demographic, health status, and physical risk factors (large waist circumference, smoking, and alcohol or drug problems), a composite of the three protective variables (control beliefs, social support, and physical exercise) at Time 1 was significantly related to functional health change. The more of these factors at Time 1, the better the health maintenance over 10 years. Among middle-aged and older adults, declines in health were significantly reduced with an increased number of protective factors.

Conclusion/Significance

Age-related declines in health were reduced among those with more protective factors up to a decade earlier in life. Modifiable psychological, social, and physical protective factors, individually and in the aggregate, are associated with maintenance of functional health, beyond the damaging effects of physical risk factors. The results are encouraging for the prospect of developing interventions to promote functional health and for reducing public health expenditures for physical disability in later life.     

The influence of anthropometric characteristics to the handgrip and pinch strength in 6-10-year old children

The aim of the study was to investigate the relationships between handgrip and pinch strength values with basic body (body height, body mass, BMI) and with specific hand anthropometric parameters (fingers spans, lengths and perimeters) in prepubertal children. Body height, body mass and five fingers spans, lengths and perimeters were measured in 461 6-10 year old Estonian children according to Visnapuu & Jürim?e (2007). BMI was calculated (kg/m2). The maximal handgrip strength of the right and left hand was measured with hand dynamometer. The right and left key and tip pinch were measured with a pinch gauge. Body height, as a rule, in combination with BMI, was the strongest predictor of handgrip strength, especially in older children (about 40-60 % of the total variance, R2 x 100). From the hand anthropometry, the most important span parameter was FS2 (see explanations in the methods), which explained about 10-50% (R2 x 100) of the total variance. In older groups, the FS1 and FS3 were added to the models. From the length parameters, the most important was IFL, which in younger groups together with MFL explained 10-30% of the total variance, and in older groups the addition of RFL increased the influence to 45% (R2 x 100). From the perimeters, the most important one was P2 which explained the variability of the handgrip strength in younger groups by 15-30% (R2 x 100) and in older groups together with P3 and P4 even 30-40%. In children, the basic anthropometric parameters (body height and BMI) contribute more to the prediction of handgrip strength than the specific anthropometric parameters. With increasing age the contribution of basic and specific hand anthropometry increases and the relation between anthropometry and handgrip strength is stronger in boys compared with girls. The relation of basic and hand anthropometry to the tip and key pinch strength is relatively low.     

Creatine supplementation and age influence muscle metabolism during exercise

Young[n = 5, 30 ± 5 (SD) yr] andmiddle-aged (n = 4, 58 ± 4 yr) menand women performed single-leg knee-extension exercise inside a wholebody magnetic resonance system. Two trials were performed 7 days apartand consisted of two 2-min bouts and a third bout continued toexhaustion, all separated by 3 min of recovery.³¹P spectra were used to determinepH and relative concentrations ofP_i, phosphocreatine (PCr), and-ATP every 10 s. The subjects consumed 0.3 g · kg¹ · day¹of a placebo (trial 1) or creatine(trial 2) for 5 days before eachtrial. During the placebo trial, the middle-aged group had a lowerresting PCr compared with the young group (35.0 ± 5.2 vs. 39.5 ± 5.1 mmol/kg, P < 0.05) and alower mean initial PCr resynthesis rate (18.1 ± 3.5 vs. 23.2 ± 6.0 mmol · kg¹ · min¹,P < 0.05). After creatinesupplementation, resting PCr increased 15%(P < 0.05) in the young group and30% (P < 0.05) in the middle-aged group to 45.7 ± 7.5 vs. 45.7 ± 5.5 mmol/kg, respectively. Mean initial PCr resynthesis rate also increased in the middle-aged group(P < 0.05) to a level not differentfrom the young group (24.3 ± 3.8 vs. 24.2 ± 3.2 mmol · kg¹ · min¹).Time to exhaustion was increased in both groups combined after creatinesupplementation (118 ± 34 vs. 154 ± 70 s,P < 0.05). In conclusion, creatinesupplementation has a greater effect on PCr availability andresynthesis rate in middle-aged compared with youngerpersons.

     

Cardiac function following prolonged exercise: influence of age

This study sought to determine the influence of age on the left ventricular (LV) response to prolonged exercise (PE; 150 min). LV systolic and diastolic performance was assessed using echocardiography (ECHO) before (pre) and 60 min following (post) exercise performed at 80% maximal aerobic power in young (28 ± 4.5 years; n = 18; mean ± SD) and middle-aged (52 ± 3.9 years; n = 18) participants. LV performance was assessed using two-dimensional ECHO, including speckle-tracking imaging, to determine LV strain (LV S) and LV S rate (LV SR), in addition to Doppler measures of diastolic function. We observed a postexercise elevation in LV S (young: -19.5 ± 2.1% vs. -21.6 ± 2.1%; middle-aged: -19.9 ± 2.3% vs. -20.8 ± 2.1%; P < 0.05) and LV SR (young: -1.19 ± 0.1 vs. -1.37 ± 0.2; middle-aged: -1.20 ± 0.2 vs. -1.38 ± 0.2; P < 0.05) during recovery in both groups. Diastolic function was reduced during recovery, including the LV SR ratio of early-to-late atrial diastolic filling (SR(e/a)), in young (2.35 ± 0.7 vs. 1.89 ± 0.5; P < 0.01) and middle-aged (1.51 ± 0.5 vs. 1.05 ± 0.2; P < 0.01) participants, as were conventional indices including the E/A ratio. Dobutamine stress ECHO revealed a postexercise depression in LV S in response to increasing dobutamine dose, which was similar in both young (pre-exercise dobutamine 0 vs. 20 μg·kg(-1)·min(-1): -19.5 ± 2.1 vs. -27.2 ± 2.2%; postexercise dobutamine 0 vs. 20 μg·kg(-1)·min(-1): -21.6 ± 2.1 vs. -23.7 ± 2.2%; P < 0.05) and middle-aged participants (pre: -19.9 ± 2.3 vs. -25.3 ± 2.7%; post: -20.8 ± 2.1 vs. -23.5 ± 2.7; P < 0.05). This was despite higher noradrenaline concentrations immediately postexercise in the middle-aged participants compared with young (4.26 ± 2.7 nmol/L vs. 3.00 ± 1.4 nmol/L; P = 0.12). These data indicate that LV dysfunction is observed following PE and that advancing age does not increase the magnitude of this response.     

The influence of exercise on the composition of developing equine joints

An overview is given of the direct and long-term effects of exercise on the biochemical characteristics of cartilage and subchondral bone, and on the metabolic activity of chondrocytes in the juvenile horse. In the experimental setup 43 foals were reared until weaning at 5 months of age under similar conditions, except for the type and amount of exercise. Fifteen foals remained at pasture (Pasture group and also control group), 14 foals were kept in box stalls (Box group), and 14 foals were kept in the same box stalls but were subjected daily to an increasing number of gallop sprints (Training group). After weaning 8 foals from each group were euthanised. All remaining 19 animals were housed together in a loose box with access to a small paddock to study a possible reversibility of exercise-induced effects. Post mortem subchondral bone and cartilage samples were collected and analysed for bone morphogenic enzymes, matrix composition, chondrocyte metabolic activity, and bone mineral density.It resulted that lack of exercise leads to a retardation of the normal development of the joint. This is largely compensated for when afterwards a more normal exercise regimen is followed. Most parameters in the Training group approximated those of the pastured foals at age 5 months. However, at age 11 months there were indications for a reduced performance of the investigated tissues in this group.It is concluded that regular, sub-maximal loading, as occurred in the Pasture group, seems best for an optimal development of the musculoskeletal tissues. The combination of short bouts of heavy exercise superimposed on a basic box rest regimen appears to have adverse effects on long-term viability of the tissues and may hence lead to an impaired resistance to injury.     

Modifications of serum glycoproteins the days following a prolonged physical exercise and the influence of physical training.

Eight male subjects (mean age 24.1 +/- 2.6 years) performed at intervals of 2 weeks successively a 3 h and two 2 h runs of different running speed. The days following the running there were moderate elevations of C-reactive protein, haptoglobin, alpha-1-acid glycoprotein, coeruloplasmin, transferrin, alpha-1-antitrypsin and plasminogen. There were small or no changes of albumin, alpha-2-macroglobulin and hemopexin. The elevations of the "acute phase reactants" were examined in three male subjects following a 2 h run before and after an endurance training period of 9 weeks. This demonstrated a decreased acute phase response after training as illustrated by the changes of C-reactive protein, haptoglobin and alpha-1-acid glycoprotein in spite of higher posttraining running speeds. Well-trained athletes have elevated levels of the serum protease inhibitors alpha-1-antitrypsin, alpha-2-macroglobulin and C1-inhibitor. These antiproteolytic glycoproteins might limit exercise-induced inflammatory reactions.     

Runs of homozygosity do not influence survival to old age

Runs of homozygosity (ROH) are extended tracts of adjacent homozygous single nucleotide polymorphisms (SNPs) that are more common in unrelated individuals than previously thought. It has been proposed that estimating ROH on a genome-wide level, by making use of the genome-wide single nucleotide polymorphism (SNP) data, will enable to indentify recessive variants underlying complex traits. Here, we examined ROH larger than 1.5 Mb individually and in combination for association with survival in 5974 participants of the Rotterdam Study. In addition, we assessed the role of overall homozygosity, expressed as a percentage of the autosomal genome that is in ROH longer than 1.5 Mb, on survival during a mean follow-up period of 12 years. None of these measures of homozygosity was associated with survival to old age.     

Body composition and performance: influence of sport and gender among adolescents

Body composition is well known to be associated with endurance performance among adult skiers; however, the association among adolescent crosscountry and alpine skiers is inadequately explored. The study sample comprised 145 male and female adolescent subjects (aged 15-17 years), including 48 crosscountry skiers, 33 alpine skiers, and 68 control subjects. Body composition (%body fat [BF], %lean mass [LM], bone mineral density [grams per centimeter squared]) was measured with a dual-emission x-ray absorptiometer, and pulse and oxygen uptake was measured at 3 break points during incremental performance tests to determine physical fitness levels. Female crosscountry and alpine skiers were found to have significantly higher %LM (mean difference = 7.7%, p < 0.001) and lower %BF (mean difference = 8.1%, p < 0.001) than did female control subjects. Male crosscountry skiers were found to have lower %BF (mean difference = 3.2%, p < 0.05) and higher %LM (mean difference = 3.3%, p < 0.01) than did male alpine skiers and higher %LM (mean difference = 3.7%, p < 0.05) and %BF (mean difference = 3.2%, p < 0.05) than did controls. This study found strong associations between %LM and the onset of blood lactate accumulation and VO2max weight adjusted thresholds among both genders of the crosscountry skiing cohort (r = 0.47-0.67, p < 0.05) and the female alpine-skiing cohort (r = 0.77-0.79, p < 0.001 for all). This study suggests that body composition is associated with physical performance amongst adolescents.     

Myosin heavy chain composition in the rat diaphragm: effect of age and exercise training.

Increases in aerobic capacity in both young and senescent rats consequent to endurance exercise training are now known to occur not only in locomotor skeletal muscle but also in diaphragm. In the current study the effects of aging and exercise training on the myosin heavy chain (MHC) composition were determined in both the costal and crural diaphragm regions of female Fischer 344 rats. Exercise training [treadmill running at 75% maximal oxygen consumption (1 h/day, 5 day/wk, x 10 wk)] resulted in similar increases in plantaris muscle citrate synthase activity in both young (5 mo) and old (23 mo) trained animals (P < 0.05). Computerized densitometric image analysis of fast and slow MHC bands revealed the ratio of fast to slow MHC to be significantly higher (P < 0.005) in the crural compared with costal diaphragm region in both age groups. In addition, a significant age-related increase (P < 0.05) in percentage of slow MHC was observed in both diaphragm regions. However, exercise training failed to change the relative proportion of slow MHC in either the costal or crural region.     

Serum potassium during exercise in Hereford calves: influence of physical conditioning

We determined how rapidly serum potassium concentration ([K+]) increased, its magnitude, and how quickly it decreased during and after a 3.5-min exercise bout at maximal speed capability in eight Hereford steers, before and after physical conditioning. Serum [K+] values rose rapidly after the start of exercise and declined rapidly to within 7% of preexercise values 5 min after exercise ceased. Before physical conditioning, serum [K+] increased from an average of 4.19 meq/l at rest to 6.71 meq/l at the highest treadmill speed the animals could sustain (1.8-2.4 m/s at a 3 degrees incline). After physical conditioning, the serum [K+] increase at comparable treadmill speeds was approximately 5% lower than before conditioning (average of 6.37 meq/l); however, the animals could now exercise from 0.6 to 0.8 m/s faster than before conditioning, and their maximal serum [K+] rose to an average of 7.47 meq/l, a 10% increase over preconditioned maximal values. We conclude that higher speeds and accompanying increases in serum [K+] attained by conditioned animals may place them at greater risk of cardiotoxicity than before conditioning.     

Body composition assessment in type 1 diabetes mellitus patients over 15 years old.

BACKGROUND: The aim of the present study was to assess the anthropometric characteristics and body composition in type 1 diabetic patients and compare the results with a randomly selected control population. MATERIAL AND METHODS: We studied 75 type 1 diabetic patients, 43 male and 32 female, recruited from consecutive diagnosed type 1 diabetic patients attending the Endocrine Unit and treated with a intensive insulin regimen, and 93 control subjects, 44 males and 49 females representative of the census of this city. We performed a dietary recall in patients and determined anthropometric characteristics, both in patients and controls, body weight, height, body-mass index, waist-hip ratio and body composition parameters: total body water, free-fat mass, body free-fat mass, fat mass and body fat by bioelectrical impedance analyser. RESULTS: In diabetic male patients, we observed lower waist-hip ratio than in controls, 0.84 +/- 0.06 vs. 0.88 +/- 0.07, p = 0.021, higher free-fat mass in female diabetic patients, 48.5 +/- 5.6 vs. 45.6 +/- 5.9 kg, p = 0.03, lower fat mass in male diabetic patients, 9.5 +/- 6.9 vs. 14.6 +/- 8.5 kg, p = 0.003. We did not find any correlation among the parameters of body composition and dietary macronutrient intake in patients. CONCLUSIONS: The present study exposes the differences in anthropometric characteristics and body composition in type 1 diabetes mellitus, especially lower waist-hip ratio in male, higher free-fat mass in female and lower fat mass in male.     

Modeling the effects of maternal nutritional status and socioeconomic variables on the anthropometric and psychological indicators of Kenyan infants from age 0-6 months

This paper presents a comprehensive empirical analysis of the factors affecting growth and psychological development of over 100 infants from birth to age 6 months in the Embu region of Kenya. The analysis was divided into four parts. First, infants' birth weight, and length and head circumference as measured few days after birth, were modeled using multiple regression models. Maternal prepregnancy body mass index (BMI), gestation period, and parity were associated with infants' anthropometric measurements (P < 0.05). Second, the scores on seven clusters of the Brazelton Neonatal Behavioral Assessment Scale were explained by health and socioeconomic indicators. While the models had poor predictive power, the scores were comparable to those reported in the literature for Puerto Rican and African American infants. The third part of the analysis modeled infant growth between 1-6 months by analyzing longitudinal data on length, head circumference, and weight. Dynamic models were postulated for the effects of nutritional, socioeconomic, and environmental factors and morbidity on anthropometric variables. The results showed that infants' calcium intakes were positively associated with length (P < 0.05). Maternal BMI and hemoglobin concentration were positively associated with infant weight (P < 0. 05); infant morbidity was negatively associated with weight (P < 0. 05). Lastly, the infants' scores at 6 months on the Bayley Motor Scale and on eight items from the Bayley Infant Behavior Record were explained using anthropometric, socioeconomic, and psychological variables. The infants' arm circumference and intake of protein were significant predictors of scores on the Bayley Motor Scale. In addition, time spent by the mother talking to the infant was positively associated with the scores on the Bayley Infant Behavior Record. The empirical results have implications for identifying vulnerable children in developing countries.