Lean Arm Research Articles

Relationship between maximal oxygen uptake on different ergometers, lean arm volume and strength in paraplegic subjects.

The present experiment was designed to study the importance of strength and muscle mass as factors limiting maximal oxygen uptake (VO2max) in wheelchair subjects. Thirteen paraplegic subjects [mean age 29.8 (8.7) years] were studied during continuous incremental exercises until exhaustion on an arm-cranking ergometer (AC), a wheelchair ergometer (WE) and motor-driven treadmill (TM). Lean arm volume (LAV) was estimated using an anthropometric method based upon the measurement of various circumferences of the arm and forearm. Maximal strength (MVF) was measured while pushing on the rim of the wheelchair for three positions of the hand on the rim (-30 degrees, 0 degrees and +30 degrees). The results indicate that paraplegic subjects reached a similar VO2max [1.23 (0.34) 1 x min(-1), 1.25 (0.38) 1 x min(-1), 1.22 (0.18) 1 x min(-1) for AC, TM and WE, respectively] and VO2max/body mass [19.7 (5.2) ml x min(-1) x kg(-1), 19.5 (6.14) ml x min(-1) x kg(-1), 19.18 (4.27) ml x min(-1) x kg(-1) for AC, TM and WE, respectively on the three ergometers. Maximal heart rate f((c) (max)) during the last minute of AC (173 (17) beats x min(-1)], TM [168 (14) beats x min(-1)], and WE [165 (16) beats x min(-1)], were correlated, but f((c) (max)) was significantly higher for AC than for TM (P < 0.03). There were significant correlations between MVF and LAV (P < 0.001) and between the MVF data obtained at different angles of the hand on the rim [311.9 (90.1) N, 313.2 (81.2) N, 257.1 (71) N, at -30 degrees, 0 degrees and +30 degrees, respectively]. There was no correlation between VO2max and LAV or MVF. The relatively low values of f((c) (max)) suggest that VO2max was, at least in part, limited by local aerobic factors instead of central cardiovascular factors. On the other hand, the lack of a significant correlation between VO2max and MVF or muscle mass was not in favour of muscle strength being the main factor limiting VO2max in our subjects.

Weight loss and wrestling training: effects on nutrition, growth, maturation, body composition, and strength.

Adolescent wrestlers (n = 9, 15.4 yr) and recreationally active control adolescent males (n = 7, 15.7 yr) were measured before, at the end (late season), and 3.5-4 mo after a wrestling season to assess the influence of dietary restriction on growth, maturation, body composition, protein nutrition, and muscular strength. Controls consumed adequate amounts of energy, carbohydrate (CHO), protein, and fat, and demonstrated normal gains in weight, fat mass (FM) and fat-free mass (FFM). Wrestlers consumed a high-CHO (61 +/- 2% kcal), low-fat (24 +/- 2% kcal) diet during the season but did not consume adequate energy (24.7 +/- 3.5 kcal.kg-1.day-1) or protein (0.9 g.kg-1.day-1). Deficient dietary intake reduced prealbumin levels (26.0 +/- 1.9 vs. 20.2 +/- 0.9 mg/dl) and slowed the accrual of lean arm and thigh cross-sectional muscle areas (AXSECT, TXSECT, respectively). For wrestlers, dietary deficiency also decreased weight (60.3 +/- 3.5 to 58.0 +/- 3.3 kg), relative fat (9.9 +/- 0.5 to 8.0 +/- 0.7%), and FM (6.0 +/- 0.5 to 4.7 +/- 0.6 kg). Postseason, wrestlers and controls consumed similar diets, and wrestlers had significant increases in prealbumin, AXSECT, and TXSECT. Wrestlers also increased their weight (6.1 +/- 0.6 kg), FFM (3.0 +/- 0.6 kg), and FM (3.2 +/- 0.5 kg) postseason. Rates of bone maturation and segmental growth were not different between the groups. The wrestlers had reductions in elbow and knee strength from preseason to late season but increases postseason. Lean tissue changes were associated with the changes in strength and power (r = 0.72-0.91, P < 0.001). After covariance for FFM or limb-specific cross section, few significant changes remained. In conclusion, dietary restriction reduced protein nutrition and muscular performance but produced little effect on linear growth and maturation. Prealbumin levels and the rate of lean tissue accrual were positively related (r = 0.43, P < or = 0.05).

A longitudinal study of lean and fat areas at the arm.

Using biceps and triceps skinfolds and upper arm circumference, areas of fat and lean tissue at the arm can be approximately determined based on a cylindrical assumption. Based on the first Zürich growth study a longitudinal analysis of estimated fat and lean areas is undertaken. Area may often be a more meaningful parameter than width in development, due to the increasing width of the limbs stretching the layer of fat. When comparing these quantities with the body mass index, correlations in boys were higher for lean area than for fat area, and about equally high for both measures in girls (around 0.8 beyond age 10). The primary goal of this investigation was to quantify the development of lean and fat arm areas from birth to adulthood, and to assess sex differences in this respect. The comparison with results obtained earlier from radiographic data is of particular interest, since such data can rarely be obtained any more, and overall this comparison can be considered encouraging. Lean area develops slowly until the onset of puberty, girls showing a slightly smaller value than boys. The pubertal spurt is very impressive in boys and moderate in girls, timed to age of peak height velocity in both sexes. Fat area changes only minimally in boys older than 16 months, and increases steadily in girls until age 16. The respective velocity curve shows a systematic up and down until age 5, when a gradual increase to a prepubertal fat spurt starts. It is interrupted by a trough in velocity--much more accentuated in boys--at puberty, and followed by a postpubertal fat spurt. When studying subgroups of subjects with a relatively high or relatively low adult body mass index, the heavy group differed relatively more in terms of fat area than lean area. Girls heavy as adults increase their fat area consistently more from about 5 years onwards. Boys later heavy show a qualitatively different pattern in puberty, with accentuated pre- and postpubertal fat spurts, but also a strong trough to a negative velocity in between.

Anaerobic power of arms in teenage boys and girls: relationship to lean tissue.

The purpose of this study was to describe anaerobic peak and mean power characteristics of arms as a function of age, gender and body composition among 50 girls and 50 boys 14 to 19 years of age. Peak (PP) and mean power (MP) output were determined during arm cranking (Wingate anaerobic test). Fat-free weight (FFW) was estimated from skinfolds, and lean arm volume (LAV) was determined by water displacement, corrected for fat volume. PP and MP increased progressively and significantly (P less than 0.05) with age for boys but not for the girls. Boys had significantly larger absolute PP and MP outputs than girls at comparable ages. PP and MP corrected for lean tissue volume were greater in older than younger boys (P less than 0.05), but did not vary significantly with age for girls. Absolute (W) PP and MP were highly correlated with LAV (r = 0.82; r = 0.75) and FFW (r = 0.84; r = 0.78) among boys. The respective r values for girls were 0.60 and 0.49 (LAV); 0.78 and 0.60 (FFW). Absolute peak and mean power, respectively, were more highly correlated with LAV (r = 0.90; r = 0.84) and FFW (r = 0.90; r = 0.85) for the combined data for boys and girls than for similar gender specific comparisons. In conclusion, both anaerobic PP and MP of arms during adolescence are highly correlated with lean tissue volume and fat-free weight, particularly among boys.

Physical fitness and blood pressure in school children.

We studied the relationship between physical fitness and blood pressure in 228 school children. The data were collected as part of the Loma Linda Child-Adolescent Blood Pressure Study. Systolic and diastolic blood pressures were lower in children above average fitness than in children below average fitness among preadolescent and adolescent boys and girls. On multivariate analysis, adjusting for skinfold thickness, an index of lean arm mass, height and age, the relationship between fitness and systolic blood pressure was statistically significant for preadolescent boys and for adolescents of both sexes. The multivariate relationship was not clearly seen for diastolic blood pressure. Multivariate techniques showed that significant correlates of fitness were obesity in preadolescents, age in adolescent boys and height in adolescent girls. Predicted pulse rates for stages 6-10 of a modified Balke treadmill protocol are given in appendix 1 for preadolescent and adolescent boys and girls.

Seasonal hunger, as experienced by the Oto and the Twa of a Ntomba village in the equatorial forest (lake Tumba, Zaire)

An anthropometric study in a Ntomba village showed how the socioeconomic categories of adult men were differently affected by seasonal weight loss. The major rainy season is experienced as a hungry season mainly because of the scarcity of animal foodstuff. During this time, 68 percent of the Oto and 75 percent of the Twa pygmoids living in the same village lost weight (0.6 kg to 2.2 kg depending on age subgroup). Among the Oto, neither the fishermen nor the young villagers who did not change their food strategy lost significant weight, although the values were much higher among the former. The seasonal fishermen, who returned to the village during the rainy season, lost the most but recovered their initial weight during the following dry season. Also, the Twa and the elderly Oto were significantly affected. The changes in lean arm circumference and subscapular skinfold appeared to be associated with the weight loss.

Sexual dimorphism in body composition changes during the pubertal period : As shown by French‐Canadian children

Size and velocity growth curves of stature to represent skeletal growth, lean arm circumference to represent muscle growth, and the sum of three skinfolds to represent fat tissue changes, are presented for a longitudinal study of Montreal school-age chidren. Both a chronological age scale, and one relative to the individual ages of peak growth velocity in stature, are used. Intercorrelations between the various components are tabulated for age groups based on the two scales. The three skinfolds are also analyzed separately. The results show that such simple anthropometric measures can be usefully taken to represent the growth of different body components. Longitudinal analysis reveals that, whereas the relationship of muscular to statural growth in boys is purely maturational, it is not so for girls, and that the different skinfolds show complex sexual differences in growth during the pubertal period.