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Muscle characteristics, energy intake and expenditure in the dancer
Abstract
The current review describes the aerobic fitness and physical effort in dance students and dance teachers during training sessions in different dance styles. The muscle fibre type distribution was compared between 10-year-olds and 20-year-old dancers after 10 years of professional dance training, and also after a detraining period. The dietary habits of female dancers were investigated and compared with the estimated daily energy intake and expenditure. The 25-30% higher estimated maximal oxygen uptake in the dance teachers and the dance students than in a randomly selected population with average physical activity indicates that dance training implies rather high demands on the cardiovascular system. Muscle fibre type composition in young dancers differs from that in the average individual and is characterized by a high percentage of type I fibres similar to that found in 20-year-old dancers. The estimated daily energy expenditure at 20% higher than estimated daily energy intake suggests that either the energy expenditure was overestimated or the energy intake was underestimated.
... 6 Furthermore, dance can increase physical and physiological ability. [7][8][9][10][11] Recently, much attention has focused on the possible role of dance as a form of psychological therapy. [12][13][14] Studies from various disciplines suggest that movement synchronization with music and with other people-i.e., dance-is fundamentally important for human well-being. ...
While dancers and dance educators express great interest in motor control as it relates to rhythmic dance, the subject remains largely uninvestigated. In order to advance our understanding of motor control, a theoretical framework called the dynamical systems approach (DSA) has been
used. The DSA was originally developed to describe mathematically the principle of synchronization patterns in nature and their change over time. In recent decades, researchers studying human motor control have attempted to describe the synchronization of rhythmic movement using a DSA. More
recently, this approach has been applied specifically to rhythmic dance movements. A series of studies that used the DSA revealed that when people synchronize rhythmic movement of a body part 1. with a different body part, 2. with other people's movement, or 3. with an auditory beat with some
phase differences, unintentional and autonomous entrainment to a specific synchronization pattern occurs. However, through practice dancers are able to overcome such entrainment and dance freely. These findings provide practical suggestions for effective ways of training in dance education.
The DSA can potentially be an effective tool for furthering our understanding of the motor control utilized in rhythmic dance.
The main purpose of the present study was to examine factors that affect bone mineral density (BMD) in female ballet dancers. Training history, Ca intake, body composition, total body BMD (TBMD) and site-specific BMD, and bone mineral content were described in twenty-four female ballet dancers (mean age 22·6 (SD 4·5) years). Training history was determined by questionnaires, Ca intake by 7 d dietary record, BMD and bone mineral content by dual-energy X-ray absorptiometry (DXA), total body water by 2H dilution, extracellular water by bromide dilution, body fat by underwater weighing (UWW; two-component model), DXA, and the four-component (4C) model. Dancers had a significantly lower body mass index (BMI 18·9 (SD 1·0) kg/m2) than controls (21·3 (SD 19) kg/m2), with significantly lower percentage body fat (17·4 (SD 3·9) v. 24·4 (SD 5·1)) but comparable fat-free mass. Mean TBMD (1·147 (SD 0 ·069) g/cm2) was significantly higher (6 %) compared with that of a reference population. These high values could be attributed to the high BMD of legs and pelvis, the weight-bearing sites of the dancer's body. No relationship was found between age, start of ballet classes, period (years) of dancing, Ca intake, and BMD (total and site-specific). However, TBMD was positively related to BMI, and negatively related to the age of menarche. BMD of the legs was significantly related to daily period (h) of training. Depending on the method used the percentage body fat ranged from 16·4 (by DXA) to 18·3 by the 4C model. These differences were significantly related to the TBMD. Percentage body fat by the different methods was not significantly different, except for DXA and 4C model. The present study showed that, despite the factors that have a negative effect on BMD, such as low body mass and late menarche, BMD in female ballet dancers was relatively high. These high values were probably caused by high levels of weight-bearing physical activity.
In order to evaluate physiological characteristics in young male ballet dancers, 27 boys (aged 9 to 16 years) who participated in a boys' dance course during the Kuopio Dance and Music Festival in June 1988 were studied. In general, the boys had started dancing at the age of 8.6 years and had been training for 4.1 years. They had, on average, three dancing sessions per week and the mean time spent on dancing was four hours per week. In the study, some anthropometric measurements were taken, the maximal oxygen uptake (VO2 max) was measured by a cycle ergometer test and the explosive strength and the mechanical power of lower extremities were evaluated by a jumping test. The results indicate that boys who train in ballet are in general moderately lean, have relatively small body size and a high degree of flexibility. The younger boys especially have only moderate aerobic power, but both explosive strength and mechanical power in leg muscles are good in ballet trained boys.
The effect of energy supplementation was evaluated in six underweight adults under free-living conditions. Customary energy intake (EI) over 4 wk and estimated body composition were defined. Then for 12 wk subjects were fed their customary EI under controlled conditions to assure stable energy reserve. Finally, intake was increased by a mean of 720 kcal/d for 8 wk adjusted to increase body fat from 9 to 18%. Body weight (means +/- SD) increased from 55.2 +/- 3.4 to 57.0 +/- 4.2 kg. Body fat gain was highly variable ranging from 0.6 to 3.8 kg. Energy expenditure (EE) by the factorial and doubly labeled water methods did not change. Fat storage accounted for 66% of the supplemental energy; 237 kcal/d remained unaccounted for. EE by the factorial method, which uses indirect calorimetry or isotopic measurements, were highly correlated (r = 0.8; p less than 0.01). Under the conditions of this study EI does not affect EE. The labeled water method permits the evaluation of energy expenditure in free-living conditions.
The purpose of the study was to estimate the genetic effect for skeletal muscle characteristics using pairs of nontwin brothers (n = 32), dizygotic (DZ) twins (n = 26), and monozygotic (MZ) twins (n = 35). They were submitted to a needle biopsy of the vastus lateralis for the determination of fiber type distribution (I, IIa, IIb) and the following enzymes were assayed for maximal activity: creatine kinase, hexokinase, phosphofructokinase (PFK), lactate dehydrogenase, malate dehydrogenase, 3-hydroxyacyl CoA dehydrogenase, and oxoglutarate dehydrogenase (OGDH). For the percentage of type I fibers, intraclass correlations were 0.33 (p less than 0.05), 0.52 (p less than 0.01), and 0.55 (p less than 0.01) in brothers and DZ and MZ twins, respectively. MZ twins exhibited significant within-pair resemblance for all enzyme activities (0.30 less than or equal to r less than or equal to 0.68). In spite of these correlations, genetic analyses performed with the twin data alone indicated that there was no significant genetic effect for muscle fiber type I, IIa, and IIb distribution and fiber areas. Although there were significant correlations in MZ twins for all muscle enzyme activities, the often nonsignificant intraclass coefficients found in brothers and DZ twins suggest that variations in enzyme activities are highly related to common environmental conditions and nongenetic factors. However, genetic factors appear to be involved in the variation of regulatory enzymes of the glycolytic (PFK) and citric acid cycle (OGDH) pathways and in the variation of the oxidative to glycolytic activity ratio (PFK/OGDH ratio). Data show that these genetic effects reach only about 25-50% of the total phenotypic variation when data are adjusted for age and sex differences.
Total free living energy expenditure was compared in lean and obese women by the new doubly labelled water method and partitioned into basal metabolism and thermogenesis plus activity by whole body calorimetry. Average energy expenditure was significantly higher in the obese group (10.22 versus 7.99 MJ/day (2445 versus 1911 kcal/day); p less than 0.001) resulting from an increase in the energy cost of both basal metabolism and physical activity. Self recorded energy intakes were accurate in the lean subjects but underestimated expenditure by 3.5 MJ/day (837 kcal/day) in the obese group. Basal metabolic rate and energy expenditure on thermogenesis plus activity were identical in the two groups when corrected for differences in fat free mass and total body mass. In the obese women in this series there was no evidence that their obesity was caused by a metabolic or behavioural defect resulting in reduced energy expenditure.
Ten competitive ballroom dance couples performed simulated competitive sequences of Modern and Latin American dance. Heart rate was telemetered during the dance sequences and related to direct measures of oxygen uptake and heart rate obtained while walking on a treadmill. Linear regression was employed to estimate gross and net energy expenditures of the dance sequences. A multivariate analysis of variance with repeated measures on the dance factor was applied to the data to test for interaction and main effects on the sex and dance factors. Overall mean heart rate values for the Modern dance sequence were 170 beats.min-1 and 173 beats.min-1 for males and females respectively. During the Latin American sequence mean overall heart rate for males was 168 beats.min-1 and 177 beats.min-1 for females. Predicted mean gross values of oxygen consumption for the males were 42.8 +/- 5.7 ml.kg-1 min-1 and 42.8 +/- 6.9 ml.kg-1 min-1 for the Modern and Latin American sequences respectively. Corresponding gross estimates of oxygen consumption for the females were 34.7 +/- 3.8 ml.kg-1 min-1 and 36.1 +/- 4.1 ml.kg-1 min-1. Males were estimated to expand 54.1 +/- 8.1 kJ.min-1 of energy during the Modern sequence and 54.0 +/- 9.6 kJ.min-1 during the Latin American sequence, while predicted energy expenditure for females was 34.7 +/- 3.8 kJ.min-1 and 36.1 +/- 4.1 kJ.min-1 for Modern and Latin American dance respectively. The results suggested that both males and females were dancing at greater than 80% of their maximum oxygen consumption. A significant difference between males and females was observed for predicted gross and net values of oxygen consumption (in L.min-1 and ml.kg-1 min-1).
The caloric expenditure of 44 healthy, lean and obese women, 8 of whom were trained athletes, was measured by indirect calorimetry. Body composition was determined. Ages ranged from 18–65 yr and body weights from 43–143 kg. Stepwise, multiple-regression analysis was used to determine whether one or several variables best predicted the resting metabolic rate (RMR) of the women. The RMR and the thermic effect of food (TEF) were measured before and after the women consumed a mixed breakfast meal.
The results showed that the currently available tables and regression equations overestimate the RMR of healthy women by 7–14%. Body weight was highly related to the RMR, and stepwise inclusions of various variables did not improve predictions of RMR. The slopes of the regression lines for nonathletes and athletes were significantly different. Regression equations for predicting RMR of women were developed: Nonathletes RMR = 795 + 7.18 kg WT; Athletes RMR = 50.4 + 21.1 kg WT. The range of RMR per kilogram body weight was wide for nonathletic, but narrow for athletic women. The metabolism of some lean and obese, nonathletic women was highly efficient, predisposing these women for developing and maintaining body fat. The TEFs were indistinguishable between nonathletic and athletic women, and formed a continuum from the lightest to the heaviest woman.
In brief: Classical ballet is a demanding discipline that until recently has been largely ignored by the medical and exercise communities. The authors studied the nutritional habits of 34 high-level classical ballet dancers during three days of a typical rehearsal week and found that they consumed only 71.6% of the recommended daily allowance for nutrients. Their average percent body fat was 16.9%. Many (17) had menstrual abnormalities, 15 had secondary amenorrhea, and 11 cited irregularities they felt were directly due to dancing. No statistical correlation could be found between the reported menstrual abnormalities and percent body fat or the age they began training.
In brief: Ten masters female long-distance runners (mean age 43.8 years) were assessed for body composition and cardiovascular endurance. The mean body fat was 18.3%, which is approximately 40% of the value for a control group of sedentary women. The only women exhibiting lower values for Percent body fat were much younger elite athletes. VO2 max averaged 43.41 ml·kg−1 min−1, which is 25% higher than that of normal women of comparative ages. The question of whether a lifetime of endurance training can offset the age- related decrease in Vo2 max is still unknown, but the increased interest in masters competition may provide the data to answer this question.
Relationships between perceived exertion, heart rate (HR) and blood lactate accumulation (HLa) were studied for three exercise modes: cycling on a bicycle ergometer, walking, and running on a treadmill, using the same group of subjects. The degree of perceived exertion was estimated both on the RPE scale and on a new category-ratio (CR) scale. Ten physically active men about 25 years old were tested on three different test occasions with stepwise increases in exercise intensity. Each test consisted of five different intensity levels with a duration of 4 min each, i.e. cycling: 50-250 W, running: 3-15 km·h-1, walking: 2-10 km·h-1. The results show that all four dependent variables (RPE, CR, HR, and HLa) can be described by monotonously increasing power functions of the general form: R = a + c(S-b)(n). The exponent (n) was about 1 for RPE and HR in cycling and running, and about 2 for walking. Exponents for CR and HLa increase during all three modes of exercise were about 2 or more with a highest exponent for HLa in walking (n = 5). Exponents within each mode of exercise were related to each other in a very consistent way. When the exponent for one of the variables changed, depending on the mode of exercise, all the others changed proportionally. When using a simple combination of HR and HLa as the independent variable and perceived exertion (according to the CR scale) as the dependent variable, a linear relationship was obtained, showing that for the kind of exercises studied, the incremental curve for perceived exertion might be predicted from a simple combination of HR and HLa.
Studies show that adult ballerinas practice poor nutrition habits, but little research has been done on adolescent dancers. The authors analyzed the diet composition of 92 female ballet dancers aged 12 to 17 enrolled in six professional schools. Three-day histories were used to compile data, and a dietitian worked with the dancers to ensure accuracy in record keeping. The results showed poor nutrition habits and low calorie and nutrition intake. Sixty percent routinely took vitamin or mineral supplements, but not properly. Unfortunately, the dancers' desire to maintain a sylphlike, willowy body makes them unwilling to consume the number of calories required for a health diet. A nutrition class in the dance school curriculum would help increase their knowledge and improve their dietary habits.
In 13 subjects intra-arterial blood pressure, heart rate, blood lactate, oxygen consumption, and pulmonary ventilation were respectively measured during submaximal and maximal arm and leg exercise. Blood pressure usually increased linearly with the oxygen uptake, this increase being significantly more pronounced for arm than leg work. The site of the catheter, mostly the femoral artery, can partly account for the difference, recorded blood pressure being constantly higher in the resting limb. Nevertheless, simultaneously recorded pressures in arm and leg give significantly higher values during cranking. Larger increases in peripheral vascular resistance in the resting extremities during arm work as well as the important static work produced by cranking are possible explanations for this difference. This fact might have clinical interest.
differences between arm and leg work; catheter position when measuring blood pressures; lactate production in small and large muscle groups
Submitted on June 15, 1964
The authors studied the nutritional and hematologic status of 22 professional ballet dancers (10 men, 12 women, mean age 25), from American Ballet Theatre by analyzing daily dietary intake and laboratory data including blood vitamin assays. The dancers had low percent body fat. Daily calorie intake was 2,967 ± 667 kcal for men and 1,673 ± 450 kcal for women. Carbohydrate consumption (38% of the total daily calorie intake for men and 50% for women) was too low for efficient energy use. Hemoglobin and red cell indexes were normal, but serum ferritin was below normal in eight women and three men. Serum chemistry values were normal. Blood vitamin assays were normal in all dancers, reflecting widespread use of vitamin supplements. By sports medicine standards the dancers' low calorie diets were suboptimal for strenuous physical exercise.
Physiologic responses to ballet exercise and [latin capital V with dot above]o2max during treadmill running were studied in elite professional ballet dancers (7 men, 8 women; age 20-30 yr) from American Ballet Theatre. Ten dancers were studied during standard 1-h ballet classes consisting of 28 min of barre and 32 min of center floor exercise. Eight dancers performed maximal treadmill running tests yielding [latin capital V with dot above]o2max values (ml-min"1-kg-1) of 48.2 (range 43.8-51.9) for men and 43.7 (range 40.9-50.1) for women. Mean [latin capital V with dot above]o2 (ml-min'1-kg'1) during barre exercise was 18.5 (38% [latin capital V with dot above]o2m") for men and 16.5 (38% [latin capital V with dot above]o2max) for women; during center floor exercise 26.3 (55% Vo2max) for men and 20.1 (46% [latin capital V with dot above]o2max) for women, with a peak of 77% [latin capital V with dot above]o2max for a male dancer. Mean caloric output values (kcal-kg-1-min-1) during barre exercise were 0.09 and 0.08 for men and women, respectively, and during center floor exercise 0.13 for men and 0.10 for women, with a peak of 0.18 for one male dancer. Estimated net caloric outputs for the entire ballet class averaged 200 kcal-h-1 for women and 300 kcal-h-1 for men. During barre exercise, HR was below the training sensitive zone (70% HR max) for significant periods of time. Peak HR (beats -min-1) was relatively high during allegro center floor exercise, averaging 178 (92% HR max) and 158 (85% HR max) for men and women, respectively. However, these were maintained for only brief durations similar to sprint or burst activities. We conclude that these physiologic data obtained during ballet class represent only a relatively modest stimulus for augmenting aerobic ([latin capital V with dot above]o2max). In conjunction with the strong isometric component in ballet exercise, along with the sprint or burst component of ballet exercise, these factors would produce in elite ballet dancers Vo2max values in the range of non-endurance athletes. (C)1982The American College of Sports Medicine
This study compared the physical effort imposed on teachers and students during dance training sessions as well as on the students when they were teaching as a part of their education. Eleven dance teachers (mean age: 39 ± 7 years) and 11 dance students (mean age: 24 ± 2 years) participated. Before the study maximal heart rate was measured in a maximal cycle ergometer test and maximal oxygen uptake (°VO2 max) was estimated from the heart rate during a submaximal test with correction for the individual maximal heart rate. Heart rate (HR), blood lactate concentration, and fluid loss were measured during the dance training sessions. Effort during sessions was expressed as the percentage of the individual maximal heart rate.°VO2 max was not significantly different between teachers and students. During training as well as teaching the average HR was approximately 70% of maximal and did not differ between training students, teachers, and students as teachers. It may be questioned whether these findings and the amount of teaching hours (25 to 29 hours per week) can explain why most dance teachers leave the profession before official retirement age.
In brief: Sixteen professional ballet dancers from the Ohio Ballet in Akron were x-rayed, tested on a Cybex dynamometer, and tested for maximal aerobic power on a treadmill to determine musculoskeletal and cardiopulmonary capabilities. The x-rays indicated that the dancers had metatarsal abnormalities characteristic of such artists. The Cybex data were considered normal for the knee. The dancers had higher than normal cardiopulmonary capacity, although it was still in the range of nonendurance athletes.
Biopsies for histochemical and biochemical analyses were taken from the vastus lateralis muscle of 55 untrained, healthy male subjects from 22 to 65 years of age. Fibre type distribution changed towards a decrease in the percentage of type II fibres, both in type IIA and type IIB fibres, whereas type IIB/IIA fibre ratio and type IIC percentage did not change with increasing age. It was found that the type IIB/flA fibre ratio was inversely related to type I fibres, i.e. subjects rich in type I fibres had a relatively smaller proportion of type IIB fibres. Fibre area determinations revealed a selective decrease in type II fibre area. Consequently, the type II/I fibre area ratio and relative type II fibre area decreased. No changes in the specific activities of Mg2+ stimulated ATPase and myokinase were observed, while the activity of lactate dehydrogenase (LDH) was higher in the youngest groups than in the oldest. LDH isozyme pattern shifted towards a decrease in percentage distribution of the muscle specific isozymes and a corresponding decrease in muscle specific activity while the activity of the heart specific isozymes did not change.
The effects of 15 days of detraining and 15 days of retraining were studied in 6 well-trained runners. Detraining resulted in significant decreases in the mean activities of succinate dehydrogenase (SDH) and lactate dehydrogenase (LDH) of 24 % and 13 %, respectively, but no significant increases in these enzyme activities occurred with retraining. Maximal oxygen uptake (VO2 max) decreased by 4% with detraining (p < 0.05), and increased by a similar amount with retraining. Performance time in an intense submaximal run decreased by 25% (p < 0.05) with inactivity, but still averaged 9% below the initial level after retraining. Maximal heart rate and peak heart rate during the performance run were higher after detraining by 4 and 9 beats per min, respectively (p < 0.05). With retraining, these heart rate values were decreased by 7 and 9 beats per min (p < 0.05). Blood lactate concentrations after the VO2 max and performance run were approximately 20% lower after detraining and retraining (p < 0.05). Muscle fibre areas for three subjects tended to be larger in biopsy samples taken after detraining and retraining. These data suggest that even short periods of detraining result in significant changes in indices of physiological capacity and function in subjects near their upper limit of adaptation, and that a longer period of retraining is necessary for muscle to re-adapt to its original trained state.
Soleus motor units of 5 and 34 week-old rats, weighing 150 and 520 g respectively, were examined for contraction time at 36 degrees C, innervation ratio as well as cross-sectional area, ATPase and SDH activity of fibres. The muscle was continuously adjusted to the growth of the animal. Between 5 and 34 weeks the proportion of Type II fibre units with 15-26 msec contraction time decreased from 33% to 10% and Type I fibre units with 27-40 msec contraction time thus increased from 67 to 90%. This was parallelled by approximately the same relative changes in number of Type II and Type I fibres.
To evaluate the effect of extreme endurance training on muscle fibre composition and activities of oxidative enzymes in different fibre types biopsies were taken from vastus lateralis, gastrocnemius and deltoideus of elite orienteers. Comparisons were made between the (trained) leg muscles and the (relatively untrained) arm muscles, and with leg muscles of 16--18 years old boys. The orienteers had the same percentage type I fibres and vastus lateralis and gastrocnemius as in deltoideus, but higher percentage type I fibres in vastus lateralis compared with the controls. The similarity between trained and untrained muscle in the orienteers suggests that training had not caused the high percentage type I fibres which rather might be the result of selection of individuals with the best prerequisites for high oxidative capacity. However, the distribution of type II subgroups in the leg muscles of the orienteers differed from both their own deltoideus and leg muscles of the controls, the relationship IIA/IIB being altered in favour of the more oxidative IIA. The leg muscles of the orienteers also showed an increased occurrence of the normally IIC fibre. These latter findings point at the possibility of a training induced alteration in the subgroup pattern. Unlike in the controls there was no significant difference in succinate dehydrogenase activity, measured in single fibres, between type I and II fibres in gastrocnemius of the orienteers. Thus, type II fibres have the ability metabolically to adapt to high oxidative demands. This might to some extent be mediated by a conversion from IIB to IIA form.
The object of the present series of experiments was to investigate the relationship in human skeletal muscle between contractile properties, such as force, velocity and fatiguability, on the one hand, and the 'quality' of the muscle in terms of its distribution of FT and ST muscle fibres and the related activities and isozyme patterns of Mg2+ stimulated ATPase, CPK and K, on the other hand, plus the adaptation of these muscle properties to strength training.
Komi, P. V., J. H. T. Viitasalo, M. Havu, A. Thorstensson, B. Sjödin and J. Karlsson. Skeletal muscle fibres and muscle enzyme activities in monozygous and dizygous twins of both sexes. Acta physiol. scand. 1977. 100. 385‐392.
Significance of the genetic component in determining the interindividual variation observed in skeletal muscle fibre composition and enzyme activities was investigated in 31 pairs of male and female monozygous (MZ) and dizygous (DZ) twins, whose ages ranged in all but one pair (11 years) from 15 to 24 years. Percent distribution of slow twitch muscle fibres and activities of Ca²⁺ and Ng²⁺ stimulated ATPases, creatine phosphokinase, myokinase, phosphorylase, lactate dehydrogenase (LDH) and distribution of its isozyme LDH‐1 were all analyzed in biopsy samples taken from the vastus lateralis muscle. The data disclosed that in contrast to DZ twins the MZ twins of both sexes had an essentially identical muscle fibre composition. Calculation of the heritability estimate for this parameter gave the values of 99.5% and 92.8%, respectively for males and females. In contrast to the fibre composition presence of a significant genetic component was not observed in any of the enzyme activities studied. It was concluded that there is a predominant genetic influence on the skeletal muscle fibre composition in man, and thus also on the potential capacity of the muscles to perform work.
In 10 children with delayed walking, muscle specimens were obtained by needle biopsy from the vastus lateralis muscle for determination of ATP, creatine phosphate (CP), glycogen and lactate concentration, as well as fibre composition and fibre size.
The values obtained are compared with corresponding results for a control group of 25 children aged 2 months–11 years. Details of the control series are given and its validity as a reference group is discussed. Six children (group I) who showed minor gross motor delay but otherwise normal development at follow-up were found to have lowered ATP, CP and glycogen concentrations, compared to 4 children (group II) who had general developmental delay, and to the control group. The children in group I were shown to have smaller fibre size and a greater difference between type 1 and 2 fibres than the children in group II and in the control group. No differences in the concentrations of metabolic substrates or the morphometric values could be detected between group II and the control group.
The primary purpose of this study was to measure the oxygen requirement of two tap dance routines. A secondary purpose was to determine if differences existed between beginning and intermediate tap dance students in the energy requirements for these dance routines. Fifteen female subjects, ranging in age from 17 to 26 years, participated in the study. Eight of the subjects were classified as beginners and seven as intermediates in their ability to tap dance. Each subject performed two tap dance routines, soft shoe and slow buck, to a medley of recorded music of 112 beats per minute (bpm). Expired gas samples were obtained from 2.5 to 3.5 and 3.5 to 4.5 minutes into each routine. There was a short rest period between routines. The mean and standard deviation of oxygen uptake was 16.6 ± 3.1 ml/kg · min for the soft shoe routine and 16.8 ± 3.4 ml/kg · min for the buck routine. There was no significant difference between these two routines or between the beginners and intermediates for the energy requirement of either dance routine (p > .05). The above values place tap dancing at 112 bpm at the same intensity as the waltz, foxtrot, rumba, Petronella, and Eightsome Reel.
Complete paucity of any data regarding the influence of habitual dance on cardiovascular-pulmonary fitness and body composition of female dancers prompted this study in which 12 female dancers and 12 sedentary female students of the same age range participated as subjects. Maximal oxygen intake was determined on the treadmill, body composition was calculated from skinfolds and vital signs were determined besides measurements of height and weight.
Dancers had significantly lower weight, lower resting heart rate, and lower diastolic blood pressure. Systolic blood pressure was also lower in dancers but the difference between the means did not reach statistical significance. Maximal oxygen intake was higher in dancers when expressed in relative terms. Dancers had also significantly lower total body fat.
In conclusion, it seems that, dance with all the variations, should be encouraged in schools as a suitable behavioral modifier of sedentary habits and for maintenance of physical fitness and ideal weight.
1. Substrate utilization in the legs during bicycle exercise was studied in five subjects when performing intermittent intense exercise (15 sec work--15 sec rest) as well as continuous exercise during 60 min, with an almost identical average power output and oxygen uptake in both situations. 2. Muscle biopsies were obtained from vastus lateralis at rest, during, and after exercise in order to determine intramuscular lipid and carbohydrate utilization. The contribution from blood-borne substrates to total oxidative metabolism was determined by arterial-femoral venous (a-fv) differences for oxygen, FFA, glucose, and lactate and leg blood flow. 3. Intermittent and continuous exercise revealed a similar glycogen depletion and the intramuscular lactate accumulation was rather small. A similar uptake of blood-borne substrate (FFA, glucose) was found in both situations whereas a release of lactate only was observed in intermittent exercise. 4. ATP and CP levels oscillated between work and rest periods in intermittent exercise but were not resynthesized to resting levels at the end of the rest periods. The mainly aerobic energy release during each work period in intermittent exercise is partly caused by myoglobin functioning as an oxygen store; this factor was calculated to be more important than ATP and CP or lactate level oscillations. 5. The metabolic response to intermittent exercise was found to be similar to that found in continuous exercise with approximately the same average power output and oxygen uptake. This indicates that some factor in the intermediary metabolism, for instance citrate, functions as a regulator retarding glycolysis and favouring lipid utilization and an aerobic energy release in intermittent exercise.
Physical growth of 212 randomly selected Swedish urban children has been investigated from birth to sixteen years as part of a prospective longitudinal study of growth and development. Twenty body measurements have been taken at specified ages. In all, about 66,000 values of measurement have been recorded. At sixteen years 179 (84.4%) ofthe original children were still regularly being followed. Thirty-three (15.6%) of the 212 children left the study at various ages. A comparison between the children who left the study and those remaining did not show any significant differences in physical growth. All recorded data have been scrutinized in order to detect errors of measurement or administrative errors. Such values have been corrected or excluded. The editorial procedures also included the adjustment of each measurement to exact target age, interpolation of missing examinations and exclusion of children with an aberrant growth pattern. When comparing the present study with older Swedish investigations a secular trend was established, while there was good agreement with other contemporary Swedish investigations. Growth charts of distance values of various body measurements are presented. In the charts standard deviation lines (+/- 1, 2, 3 SD) and mean values are plotted. A logarithmic time scale (logarithmic conceptional age) has been used for both practical and theoretical reasons. When evaluating individual values in comparison with reference values standard deviations should be used rather than centiles. With this approach even grossly deviating values can be evaluated. Longitudinal follow-up of individual children and comparison of children of different ages will also be facilitated by this approach.
Methods of non-invasive monitoring of training status for prevention of staleness in athletes and dancers need to be developed and evaluated. In order to monitor physiologic and psychologic changes which may result from overstraining, we measured urinary excretion of free norepinephrine (NE) and epinephrine (E) and mood states over 5 weeks of an intensive ballet season in 12 (6 men, 6 women) professional dancers. First morning urine voids (AM) were collected at the start of the season and following the only off-day each week with final collection on the last day of the season. Additional urine samples were collected before (pre) and after (post) each dancer's subjectively-rated single most difficult performance. Profile of Mood States (POMS) was completed by and collected from each dancer at the same time as the AM urine samples. NE and E excretions (nanograms per mg creatinine) increased significantly with time (r = 0.91, p less than 0.02, and r = 0.94, p less than 0.01, respectively) from beginning to end of season, and pre to post (51.1 +/- 7.3 to 115.6 +/- 19.7, p less than 0.001 and 19.3 +/- 3.2 to 37.7 +/- 4.2, p less than 0.001, respectively). Women had a significantly higher excretion of NE than did men (F = 9.33, p = 0.014) and no gender differences existed in the excretion of E (F = 0.57, p = 0.484).(ABSTRACT TRUNCATED AT 250 WORDS)
Age-related changes in muscle fibre characteristics have been presented in cross-sectional studies previously. The aim of the present study was to investigate longitudinally whether the muscle fibre type composition and muscle fibre area change from adolescence to adulthood. Fifty-five men and 28 women were studied at the age of 16 and again at the age of 27. Biopsies were taken from the vastus lateralis muscle and analysed for fibre types (I, IIA, IIB, IIC) and fibre areas. Different development of fibre type composition with increased age were seen in women and men: the type I percentage tended to increase in the women (51 +/- 9 to 55 +/- 12) and decrease significantly in the men (55 +/- 12 to 48 +/- 13). The fibre areas remained unchanged in both sexes. It is suggested that there is a sex-related fibre adaptation to increased age.
To determine whether female athletes have unusually low energy requirements as suggested by many food intake studies, energy expenditure (EE) and intake were assessed in nine elite distance runners [26 +/- 3 (SD) yr, 53 +/- 4 kg, 12 +/- 3% body fat, and 66 +/- 4 ml.kg-1.min-1 maximal O2 uptake]. Subjects were admitted to a metabolic ward for 40 h during which 24-h sedentary EE was measured in a respiratory chamber. Free-living EE was then assessed by the doubly labeled water method for the next 6 days while the women recorded all food intake, daily body weight, and training mileage (10 +/- 3 miles/day). Energy intakes estimated from free-living EE (2,826 +/- 312 kcal/day) and body weight changes (-84 +/- 71 g/day) averaged 221 +/- 550 kcal/day in excess of those calculated from food records (2,193 +/- 466 kcal/day). The energy cost of training (1,087 +/- 244 kcal/day) was calculated as the difference between free-living EE and 24-h EE in the respiratory chamber (1,681 +/- 84 kcal/day) corrected for the thermic effect of food of the extra energy intake. These data do not support the hypothesis that training as a distance runner results in metabolic adaptations that lower energy requirements in women.
The female distance runner is considered at high risk for secondary amenorrhea and reduced spinal bone mineral, and recent studies have suggested that these disturbances might be nutritionally or metabolically linked. The present study investigated 1) whether there is a physiological basis by which the amenorrheic runner might maintain weight at a lower than expected caloric intake, i.e., conservation of energy, and 2) the potential interactions of reduced energy intake, secondary amenorrhea, and reductions in bone density. Subjects included 13 elite female distance runners, 8 amenorrheic and 5 eumenorrheic, and 5 untrained female controls. Body composition by hydrostatic weighing, bone density and mineral content by dual-photon absorptiometry, and blood samples for hormonal analyses (once per week for 4 wk) were obtained, as were duplicate measures for resting metabolic rate, thermic effect of a meal, and the energy cost of specific (treadmill) and nonspecific (cycle ergometer) physical activity. Energy intake and energy expenditure were estimated by 3-day logs. Energy intakes did not differ (1,781, 1,690, and 1,763 kcal), nor did energy expenditures (2,480, 2,314, and 2,268 kcal), for the amenorrheic and eumenorrheic runner and control groups, respectively. The difference between reported energy intake and estimated energy expenditure of 500-700 kcal was likely due to underreporting or restricting intake, inasmuch as there was no evidence of energy conservation. A possible link was suggested between disordered eating, secondary amenorrhea, and bone mineral loss.
This study investigated metabolic and nutritional factors in association with athletic menstrual dysfunction (AMD). Three groups of women were studied: amenorrheic runners (amenorrheic), eumenorrheic runners (eumenorrheic), and eumenorrheic sedentary controls (sedentary). Amenorrheic and eumenorrheic were similar in age, weight, percent body fat by hydrodensitometry, training pace and mileage, best 10 km race time, years running, and maximal oxygen consumption. When adjusted for body weight or for fat-free mass by analysis of covariance, RMR was significantly lower in amenorrheic than in eumenorrheic and sedentary. The daily caloric intakes of the groups did not differ significantly, but the amenorrheic scored significantly higher than the eumenorrheic and sedentary on a scale of aberrant eating patterns. Amenorrheic high mileage runners seem to have a less adequate diet than eumenorrheic runners but appear to maintain energy balance and stable weight through a reduction in RMR.
Thirty-eight female subjects (M +/ SD = 33 +/- 3.0 years) had VO2max measured on the cycle ergometer (M +/- SD = 37.3 +/- 6.4 ml.kg-1.min-1) and on the treadmill (M +/- SD = 41.3 +/- 6.6 ml.kg-1.min-1). VO2max was estimated for each subject from heart rate (HR) at submaximal workloads on the cycle ergometer using the Astrand-Rhyming nomogram (A/R) and the extrapolation method (XTP). VO2max was also estimated from three field tests: 1.5-mile run (RUN) (independent variable [IV] = time), mile walk (WALK) (IV = time, age, HR, gender, body weight), and the Queens College Step Test (ST) (IV = HR during 5-20 s recovery). Repeated measure ANOVA revealed significant mean differences between the criterion cycle ergometer VO2max versus A/R and XTP (20 and 12% overestimation). The WALK, RUN, and ST VO2max values were not significantly different from the criterion treadmill VO2max. The correlation between criterion VO2max estimated from the WALK and RUN were r = .73 (SEE = 4.57 ml,kg-1.min-1) and r = .79 (SEE = 4.13 ml.kg-1.min-1), respectively. The ST, A/R, and XTP had higher SEEs (13-13.5% of the mean) and lower r s (r = .55 to r = .66). These results suggest both the WALK and RUN tests are satisfactory predictors of VO2max in 30 to 39-year-old females.
To test the accuracy of self-reported energy intake, reported intake was compared with measured energy expenditure. Results from nine studies were reviewed in which intake data were obtained by recall or weighed record for at least 7 days. Expenditure was measured for 7 days or more by the doubly labelled water method. Individual differences between reported intake and expenditure were large (range +25 to -76%). Group mean differences were smaller. Lean, nonathletic groups living in industrialized countries demonstrated the smallest mean difference between self-reported energy intakes and expenditure (0 to -20%). Obese populations demonstrated the largest mean differences (-35 and -50%), but women living in the Gambia and elite athletes also demonstrated large mean differences. Most of the difference appears to be due to under-reporting, but some subjects lost weight during the reporting period indicating that some of the difference was due to undereating. Because the greatest bias was observed in obese subjects, current methods for self-reported energy intake are not recommended for use in obesity research.
Dietary intake of energy, protein, fat and carbohydrates in female dance students compared to female music students was estimated by a dietary history method. Energy requirement was estimated from body weight and physical activity both by a standard formula and from the measured work intensity during dance training. Meal patterns showed significant differences in four types of meals on week-days and in one type on weekends. The intake of protein, fat and carbohydrates in absolute amounts and the percentage of energy derived from protein were not significantly different between the two groups. The fraction of energy derived from carbohydrates was higher and that from fat was lower in the dancers than in the musicians. Energy intake was of similar magnitude for the dancers and the musicians (8.3 +/- 1.9 MJ vs. 8.3 +/- 1.7 MJ), while the estimated energy requirement was greater for the dancers (10.3 +/- 0.7 MJ vs. 8.9 +/- 0.4 MJ). The reason for the apparent discrepancy between energy intake and energy requirement of approximately 2 MJ in the dancers is not obvious. The energy intake may have been underestimated. Alternatively, the energy requirement may have been overestimated. The resting metabolic rate may have been depressed by years of low energy intake. In addition, as suggested by some authors, training as such may lower the resting metabolic rate as well as the diet-induced thermogenesis.
The purpose of the present study was to describe the extent of the variation in some of the common characteristics of human skeletal muscle. A total of 418 biopsies was obtained from the vastus lateralis muscle of 270 healthy sedentary and 148 physically active individuals of both sexes. The lowest and highest proportion of type I muscle fiber observed were 15 and 85%, respectively. Coefficients of variation (CV) reached approximately 30% for the proportion of types I and IIA fibers and were two times higher for the proportion of type IIB fiber. The smallest and largest mean muscle fiber cross-sectional areas (CSA) were approximately 1,100 microns 2 and 9,500 microns 2, respectively. Mean CSA of the various fiber types exhibited CV of approximately 23%. CV reached 30% for the activity of creatine kinase, ranged between 28 and 41% for the glycolytic enzyme markers, and between 34 and 44% for the aerobic-oxidative enzyme markers. The mean proportion of type I fiber was lower in male than in female muscles, whereas the mean CSA of all fiber types was smaller in female than in male muscles. Levels of glycolytic enzyme markers were higher in male than in female skeletal muscles. However, activities of aerobic-oxidative enzyme markers were similar in males and females. These results reveal the existence of large interindividual variability and gender differences in the most common characteristics of the human skeletal muscle.
The purpose of this study was to examine the possible relationship between the thermogenic response to a mixed meal and the aerobic capacity in healthy subjects. Fourteen male subjects participated, and their maximal oxygen uptake was determined on a bicycle exercise ergometer. Two groups, each comprising seven individuals, were compared: a well-trained group, with an oxygen uptake of 58 +/- 2 ml min-1 kg-1 and a sedentary group, with an oxygen uptake of 39 +/- 2 ml min-1 kg-1. Respiratory gas exchange was measured continuously for 1 h in the basal state and then for 3 h postprandially. The subjects ingested a test meal in liquid form, consisting of 17% kJ protein, 28% kJ lipids and 55% kJ carbohydrates, and corresponding to 60% of the individually computed 24-h basal energy expenditure. Basal oxygen uptake and energy expenditure were similar in the two groups. After the meal, pulmonary oxygen uptake and energy expenditure rose rapidly and reached a plateau after 1 h. The responses were no different in the two groups: the average rise in pulmonary oxygen uptake above basal during the whole study period was 24.0 +/- 2.1% in well-trained and 26.7 +/- 1.5% in sedentary subjects (NS); the corresponding values for energy expenditure were 25.0 +/- 2.1% and 29.0 +/- 1.6% (NS). Also, when expressed in absolute terms the increments above basal were not significantly different. There was no discernible relationship between the individual thermogenic response and maximal oxygen uptake. In conclusion, the present findings do not indicate that diet-induced thermogenesis is proportional to aerobic capacity in healthy young men.
1. The maximum activities of hexokinase, 6-phosphofructokinase and oxoglutarate dehydrogenase, together with capillary density and fibre composition, have been measured in muscle from male and female untrained, medium-trained and well trained individuals. 2. The activity of hexokinase was almost identical in muscle from the three groups, whereas that of 6-phosphofructokinase decreased and that of oxoglutarate dehydrogenase increased with increased training. Values of maximum rate of O2 uptake (VO2, max) were also measured and were 21% higher in medium-trained and 49% higher in well trained compared to untrained individuals, whereas oxoglutarate dehydrogenase activities were 39% and 90% higher respectively. 3. There was a good positive correlation between the activity of oxoglutarate dehydrogenase and the percentage of type I fibres but the correlation between VO2, max and oxoglutarate dehydrogenase activity was less good. Changes in the values of VO2, max represent the effects on the circulatory and respiratory system whereas those in oxoglutarate dehydrogenase represent local effects of endurance training.
This study assessed a simple factorial method to predict energy expenditure (EE) in confined and free-living subjects. Thirteen subjects (seven male, 6 female) were studied on four occasions each. Measurements included BMR, 24-h EE by continuous respirometry, 4-d records of intake and activities, body weight, and urine collections. Agreement between measured and predicted 24-h EE was within +/- 2% for group results and +/- 10% for most individuals. Individual agreement was improved to within +/- 5% by using measured rather than predicted BMR. Habitual energy intake was 7.3% greater (p less than 0.05) than predicted EE in males and 5.1% less (NS) in females. Validatory data suggested overrecording of intake in males and underrecording in females. Large individual differences between habitual intake and predicted EE were observed but were significantly (p less than 0.01) correlated with both weight change and protein balance. Our simple factorial method provided acceptable estimates of EE in the subjects studied.
The purpose was to compare the resting metabolic rate (RMR) and thermic effect of a meal (TEM) in exercise trained and untrained individuals. TEM was measured for 180 min and blood samples were drawn for determination of plasma insulin, glucose, triiodothyronine (T3) and thyroxine (T4). Results indicated that highly trained subjects demonstrated a higher RMR when expressed in kilocalories per minute and per kilogram fat-free weight (FFW) than do untrained subjects. TEM was lower in trained (55.8 +/- 3.1 kcal) than in untrained (79.2 +/- 3.7 kcal) subjects. No differences were noted between the two groups for plasma levels of insulin, glucose, T3, and T4. A higher RMR and lower TEM persisted in the trained group compared with the untrained group when groups were matched for FFW and body fat. Results support a higher RMR in endurance athletes and a lower TEM even after control is exerted over differences in body composition.
Given the heightened interest in nutritional aspects of exercise, and an increase in athletic participation by women, it appeared timely to review the nutritional implications of exercise in women. The initial part of this paper contains a compilation of published studies on the nutrient intakes of female athletes. These reveal that most groups of athletes have adequate nutrient intakes, and that their vitamin and mineral intakes appear to be superior to those of nonathletic women. The average energy intake of athletes in studies summarized in this paper was 2069 kcal, and for certain groups of athletes, energy intakes were even lower. How these women manage to train intensely while consuming energy intakes similar to those of sedentary women is not readily apparent, and for this reason, the remainder of the paper discusses energy balance as affected by activity. Methodological considerations related to assessment of the components of the energy balance equation (food intake, energy expenditure, and body energy stores) are presented, with a focus on considerations in women. The effects of activity on each of these components are then discussed in an attempt to determine whether some form of energy conservation may occur. Finally, effects of activity on the menstrual cycle are reviewed. The observed changes are discussed in relation to nutrition 1) in terms of how nutrition may play a role in their causation; and 2) in terms of their nutritional implications for the amenorrheic athlete, specifically as regards energy balance and bone density.