Effect of rest duration between sets on fatigue and recovery after short intense plyometric exercise.

Plyometric training is characterized by high-intensity exercise which is performed in short term efforts divided into sets. The purpose of the present study was twofold: first, to investigate the effects of three distinct plyometric exercise protocols, each with varying work-to-rest ratios, on muscle fatigue and recovery using an incline-plane training machine; and second, to assess the relationship between changes in lower limb muscle strength and power and the biochemical response to the three exercise variants employed. Forty-five adult males were randomly divided into 3 groups (n = 15) performing an exercise of 60 rebounds on an incline-plane training machine. The G0 group performed continuous exercise, while the G45 and G90 groups completed 4 sets of 15 repetitions, each set lasting 45 s with 45 s rest in G45 (work-to-rest ratio of 1:1) and 90 s rest in G90 (1:2 ratio). Changes in muscle torques of knee extensors and flexors, as well as blood lactate (LA) and ammonia levels, were assessed before and every 5 min for 30 min after completing the workout. The results showed significantly higher (p < 0.001) average power across all jumps generated during intermittent compared to continuous exercise. The greatest decrease in knee extensor strength immediately post-exercise was recorded in group G0 and the least in G90. The post-exercise time course of LA changes followed a similar pattern in all groups, while the longer the interval between sets, the faster LA returned to baseline. Intermittent exercise had a more favourable effect on muscle energy metabolism and recovery than continuous exercise, and the work-to-rest ratio of 1:2 in plyometric exercises was sufficient rest time to allow the continuation of exercise in subsequent sets at similar intensity.

Metabolic Risk Factors in Young Men With Healthy Body Fat But Different Level of Physical Activity.

The study was performed to evaluate metabolic risk in young lean individuals characterized by different physical activity. A total of 194 students (93 active with 5-7 h weekly physical activity and 101 inactive) were accepted for the study. The following percentages of body fat were accepted as characteristic for lean men: 14% to 17% in active and 18% to 24% in inactive participants. Circulating glucose, insulin, triacylglycerols (TG), total cholesterol (TC), and high-dendity lipoprotein (HDL)-cholesterol (HDL-C) were assayed. Daily intake of energy and macronutrients was briefly assessed from 24 h food records collected over 4 days preceding blood collection. Insulin and TG differed with respect to physical activity and was lower by 37.5% and 12.5%, respectively, in active versus inactive participants. In active students with upper quartile of body fat percentage, the only significant difference was found between circulating insulin (by 28%, p < .04). In inactive participants with upper quartile of body fat, significant differences were found between levels of insulin and TG (by 25% and by 37.5%, respectively). Diet composition did not differ with respect to the percentage of energy derived from protein, fat, and carbohydrates. An inverse association between insulin level and the percentage of body fat seems to be physiological one because it has been noted in both active and inactive individuals. On the contrary, elevation in circulating TG found exclusively in inactive subjects seems to be secondary to the changes in adiposity and circulating insulin and is followed by tendency to higher levels of TC.

Effect of concentric vs. eccentric variant of lower limbs plyometric training on biomechanical and biochemical parameters.

AbstractThe study aimed to compare the effectiveness of two variants of 4 weeks plyometric training involving jumping up (dominance of concentric muscle work, UP) and jumping down (dominance of eccentric muscle work, DOWN) the stairs. Twenty-six young men were divided into two groups: UP (n = 13) and DOWN (n = 13). Control measurements of the muscle torques, vertical jumps, and creatine kinase (CK) activity were performed every week. The training resulted in significant changes (p < 0.001) in the muscle torques of the hip extensors (Δ ≈ 20% in both groups) and plantar flexors (ΔUP = 25%, ΔDOWN = 33%), but in the muscle torques of the knee extensors a significant (p < 0.001) increase occurred only in the group jumping down the stairs (ΔDOWN ≈ 15%). Furthermore, a significant increase (p < 0.001) of the height of the vertical jump was noted in the study only in the group jumping down (ΔDOWN = 8%). Training with the dominance of eccentric work caused greater weekly changes in the activity of creatine kinase in the plasma. The study confirmed that the exercise involving jumping on the stairs is viable in plyometric training, as it is an effective means of training the strength of the muscles of the lower limbs and vertical jump height, with a greater share assigned to jumping down consecutive steps.

Changes in Anthropometry and Selected Metabolic Parameters in Young Men During Their First Year of Study at a University of Physical Education.

This study aims to determine main health-related anthropometric and metabolic parameters in young physically active male students in their first year of study. Sixty one male students from a Polish university of physical education were studied twice-at the beginning of their first and second academic years. Body weight, height, waist circumference, and body composition were measured. Plasma levels of thyroid-stimulating hormone (TSH), leptin, cortisol, and insulin, as well as insulin resistance (IR) using the homeostatic model assessment (HOMA) were determined. In 64% of the participants body weight and body mass index (BMI) significantly increased during the study. An average students' weight gain amounted to 1.2 kg. In most of the subjects it resulted from the increase of fat-free mass ( r = .886, p < .001). TSH and leptin levels did not change, but a significant increase of cortisol levels and a tendency toward decreased insulin levels and also HOMA-IR values were observed. However, there were no significant correlations identified between the changes in anthropometric and biochemical parameters. The study revealed that body weight gain seen in male students during their first year at the university of physical education was mainly due to the increase in fat-free mass. Apart from anthropometrics, changes in their insulin and cortisol levels were also detected, but further studies are required to evaluate these findings. The documented insufficient energy and carbohydrates consumption in physically active male students proves the need for nutritional education among them.

Somatic characteristics and motor fitness of elite and sub-elite Polish male badminton players.

BACKGROUND: An appropriate level of somatic and fitness traits is believed to contribute to success in an international badminton competitions however, these have not been sufficiently explored in elite Polish badminton players. Therefore, the aim of the study was to assess somatic build and physical fitness of elite and sub-elite Polish badminton players and to identify key traits that determine achieving sporting success in badminton. METHODS: The study participants comprised 20 men from the Polish Badminton National Teams A (elite; N.=9) and B (sub-elite; N.=11). In all participants body height, arm span, body mass, body fat, fat free mass and Body Mass Index (BMI) were assessed. Fitness tests included two badminton-specific on-court movement tests and cycloergometer test to assess maximal oxygen uptake (VO2max). RESULTS: Studied players did not differ in body height and arm span however, elite players were heavier by about 10 kg and had significantly higher values of BMI and body fat. Irrespectively of sport level, elite and subelite badminton players achieved comparable results in both on-court tests as well as with respect to VO2max (55.9 and 57.2 mL/min/kg, respectively). Cluster analysis allowed to indirectly describe the profile of somatic traits and physical fitness that facilitates achieving success in badminton. CONCLUSIONS: Relatively small body size of badminton players can be considered advantageous in sport competitions. It also seems that aerobic capacity contributes to achieving sport success in badminton to a much lower degree than the badminton-specific on-court skills.

Body shape index versus body mass index as correlates of health risk in young healthy sedentary men.

Recently a new simply calculated index of body composition -a body shape index (ABSI) has been introduced as an index more reliable than BMI of association between body composition and all-cause mortality. However, until now associations between ABSI and metabolic risk factors have not been evaluated. A total of 114 male university students not engaged in any planned physical activity participated in the present study. Anthropometric measurements (weight, height, waist circumference) were recorded. Body mass index (BMI) was calculated from weight and height, body shape index (ABSI) was calculated from waist circumference, weight, height and BMI. Blood was withdrawn after an overnight fast from the antecubital vein. Triacylglycerols, total cholesterol and HDL-cholesterol levels in plasma were determined using colorimetric methods and Randox commercial kits. Plasma LDL-cholesterol concentrations were calculated according to the Friedewald formula. Circulating insulin was assayed using a standard radioimmunological method with monoclonal antibodies against insulin and BioSource commercial kits. BMI was slightly, but significantly correlated only with circulating TG (r=0.330, p < 0.001) In contrast, ABSI was slightly, but significantly correlated with plasma levels of insulin (r=0.360, p<0.001), TC (r=0.270, p<0.002), LDL-C and non-HDL-C (r=0.300, p<0.001). In participants at the upper quartile of BMI circulating TG was higher (by 50%, p<0.05) than in their counterparts at the lower BMI quartile. Subjects representing the upper quartile of ABSI were characterized by higher plasma levels of insulin, TC, LDL-C and non-HDL in comparison with subjects at the lower ABSI quartile. (by 92 %, 11. %, 29 % and 21 % respectively, p<0.001). ABSI, a new simply calculated index of body fat seems to more accurately depict the variability in circulating insulin and lipoproteins than BMI at least in young, healthy male subjects.

Relationship between the percentage of body fat and surrogate indices of fatness in male and female Polish active and sedentary students.

BACKGROUND: Limited data have indicated that body mass index (BMI), waist circumference (WC), waist to hip ratio (WHR) and waist to height ratio (WHtR) of athletes and young adults provide misleading results concerning body fat content. This study was aimed at the evaluation of the relationship between different surrogate indices of fatness (BMI, WC, WHR, WHtR and body adiposity index (BAI)) with the percentage of body fat in Polish students with respect to their sex and physical activity. METHODS: A total of 272 students volunteered to participate in the study. Of these students, 177 physical education students (90 males and 87 females) were accepted as active (physical activity of 7 to 9 hours/week); and 95 students of other specializations (49 males and 46 females) were accepted as sedentary (physical activity of 1.5 hours/week). Weight, height, waist and hip circumferences were measured, and BMI, WHR, WHtR and BAI were calculated. Body fat percentage was assessed using four skinfold measurements. RESULTS: Classification of fatness according to the BMI and the percentage of body fat have indicated that BMI overestimates fatness in lean subjects (active men and women, sedentary men), but underestimates body fat in obese subjects (sedentary women). In all groups, BMI, WHR, WHtR and BAI were significantly correlated with the percentage of body fat (with the exception of WHR and hip circumference in active and sedentary women, respectively). However, coefficients of determination not exceeding 50% and Lin's concordance correlation coefficients lower than 0.9 indicated no relationship between measured and calculated body fat. CONCLUSION: The findings in the present study support the concept that irrespective of physical activity and sex none of the calculated indices of fatness are useful in the determination of body fat in young adults. Thus, it seems that easily calculated indices may contribute to distorted body image and unhealthy dietary habits observed in many young adults in Western countries, but also in female athletes.

Variability in HOMA-IR, lipoprotein profile and selected hormones in young active men.

Resistance to insulin actions is contributing to many metabolic disturbances. Such factors as age, sex, nutrition, body fat, and physical activity determine body insulin resistance. Present study attempted to asses insulin resistance and its metabolic effects with respect to energy intake in young, lean, and active men. A total of 87 men aged 18-23 participated in the study. Plasma levels of glucose, insulin, lipoproteins, cortisol, and TSH were determined. Insulin resistance was expressed as Homeostasis Model Assessment for Insulin Resistance (HOMA-IR) and calculated using homeostatic model. The median value of HOMA-IR (1.344) was used to divide subjects into two groups. Men did not differ in anthropometric parameters, daily physical activity, and plasma TSH and cortisol levels. However, in men with higher HOMA-IR significantly lower daily energy intake was observed concomitantly with higher TG, TC, and HDL-C concentrations in plasma versus their counterparts with lower HOMA-IR. Exclusively in subjects with higher HOMA-IR significant and positive correlation was noted between HOMA-IR and TC and LDL-C. We concluded that despite a normal body weight and physical activity, a subset of young men displayed unfavorable changes in insulin sensitivity and lipid profile, probably due to insufficient energy intake.

Evaluation of the effectiveness of training on a machine with a variable-cam.

The aim of the study was to assess the effectiveness of the training of elbow flexors through the use of 2 machines, one of which was equipped with a disc plate of constant radius, the other one with a variable-cam having a radius adjustable to muscle strength. The experiment included 45 men divided into 3 equal groups: training group A (variable-cam), training group B (circle), and control group C. The training lasted for 8 weeks, 3 times a week. In order to control the effects, the values of peak torque and power of the flexor muscles of the elbow were isokinetically measured for the angular velocities of 30°/s and 60°/s. Also taken were anthropometric measurements of the arm and the creatine kinase (CK) activity in the blood plasma. As a result of the training, significant increases of biomechanical values were noted only in group A: power increased over 20%, the peak torque over 14%. After the training, significant increases of arm circumference in the relaxed position were noted in group A (17 mm), as well as in group B (11 mm). Also, some changes in CK activity were observed between Monday and Friday in a training week. On the basis of the experimental measurements, it may be ascertained that training elbow flexor muscles on a machine with a variable-cam is more efficient for increases in strength and power, as well as for some anthropometric parameters, than training on a machine with a disc plate.

The physique and body composition of students studying physical education: a preliminary report.

INTRODUCTION: Young people who study physical education are a priori regarded as having proper body structure and body composition. This assumption cannot be confirmed in the subject literature. AIM OF THE STUDY: To determine the basic auxological parameters in youth who study physical education. MATERIAL AND METHODS: 235 first-year students studying physical education were examined: 32% women (n=74) and 68% men (n=161). The students' body height, weight, waist, and hip circumference were measured. Body composition (bioimpedance method), specifying the body fat percentage (FM%) and fat free mass (FFM%) was also assessed. RESULTS: The mean normalized height of the female body was 0.48±1.07 SDS, and for the male body 0.51±1.04 SDS. The mean normalized weight for women was 0.4±0.94 SDS, and for men it was 0.83±0.9 SDS. The mean fat percentage in the body composition of women and men was, respectively, 21.5±5.06, ranging from 10.16% to 35.06%, and 12.5±3.97, ranging from 4.36% to 22.28%. In one-third of the women, the percentage of fat in the body composition was higher than 25%. CONCLUSIONS: 1. Young people who choose to study physical education and physical culture are characterized by greater height and greater body weight than the general population, regardless of gender. 2. Short persons study physical education less often than tall individuals. 3. The greater body weight observed in the majority of students studying physical education, in comparison to that of the general population, was caused by a dominant percentage of lean body mass in body composition; unexpectedly, however, some women were observed to have relatively high fat content. 4. Use of the body mass index and waist-hip ratio was not a sufficiently sensitive screening examination to detect fatness in physically active young adults; therefore, it should not substitute for the determination of fat content in body composition.

[Fat content in young adults determined by skinfolds and body composition analyzator]. / Zawartosc tkanki tluszczowej u mlodych doroslych oceniona na podstawie pomiaru faldów skórno-tluszczowych i wskazan analizatora skladu ciala

INTRODUCTION: Body composition analysis is essential in assessing the nutritional status, as well as the risk of developing diseases associated with abnormal body fat content. At present, many methods are available to measure the amount and distribution of body fat. Among them, of particular importance are those methods that are simple, do not require expensive equipment and allow the assessment of the body composition of a large number of people (population study). However, previous observations show that they provide different results, and, therefore, further analysis and comparisons should be conducted in different age, sex and body composition groups. AIM OF THE STUDY: The goal was to compare the anthropometric and bioelectrical impedance analysis (BIA) methods used to assess body composition in young women and men. MATERIAL AND METHODS: 65 women and 109 men, physical education students, took part in the study. Average chronological age of the women was 20.5±3.1 years and men 19.9±1.4 years. Body weight, height and thickness of 4 skinfolds (SF; over the biceps, triceps, subscapular, suprailiac) were measured. The percentage of body fat in the anthropometric method was calculated using the Durnin and Womersley's equation. Assessment of body composition was also made by the BIA method. All the measurements in every person were made on the same day. RESULTS: The mean BMI was 21.4±1.9 in women and 23.9±2.4 in men. The mean percentage of body fat obtained by anthropometric method was 16.7±7.1% in women and 10.2±6.6% in men. The amount of body fat estimated by the BIA method was higher than that calculated by skinfold thickness among female students by about 5% (p <0.001), while for male students by 3% (p <0.001). The correlation coefficients between the anthropometric method and BIA method for women and men were 0.448 (p <0.05) and 0.380 (p <0.05), respectively. CONCLUSIONS: The anthropometric and BIA methods provide different results of body fat content, especially in women, so they should not be used interchangeably.

[Retrospective assessment of growth monitoring of subjects born between 1989-1991]. / Retrospektywna ocena monitorowania przebiegu wzrastania osób urodzonych w latach 1989-1991.

INTRODUCTION: Systematically taken measurements of body length, and--after 18 months of life--height, facilitate the correct monitoring of the course of physical development in children and teenagers. Measuring body mass only is incorrect and may lead to a faulty evaluation of the patient's condition. AIM OF STUDY: Assessment of frequency of measurements of body mass and height during the developmental period among students born between 1989-1991. MATERIAL AND METHODS: For 109 subjects (52% women), age 20.0±1.0 year, range 19.1-23.8 years of age, measurements at birth, duration of the mother's pregnancy and frequency of measurements of body mass and weight until the 18th year of life. RESULTS: The frequency of measurements of body length and height was the highest during the 1st and 2nd year of life, on average every 3 months during the 1st year and every 6 months during the 2nd year. However, during the 1st year as many as 1/3 of children were assessed incorrectly by having only their body mass measured. During the 2nd year, regardless of body mass at birth, measurements were taken more frequently than during the 1st year, which may suggest inadequate preparation of the medical personnel to take measurements of the baby's body length. Measurements of body height and even body mass during puberty and the growth spurt were carried out in a far too small percentage of subjects. CONCLUSIONS: 1. Body mass measurements are all too frequently not accompanied by measurements of body length or height, with the result that the physician is unable to assess the child's growth pattern. 2. Measurements of body height and mass were taken too infrequently during childhood and puberty, which in many cases makes it impossible to assess the subject's physical development.

[Incidence of low birth weight in academic youth]. / Czestosc wystepowania niskiej urodzeniowej masy ciala w populacji studiujacej mlodziezy.

INTRODUCTION: Birth parameters are used to evaluate infant's maturity and to indicate children with a potential risk of growing disorders and metabolic complications in later life. Low birth weight can be connected with higher fat content, especially in the abdominal part in adult individuals. Low birth weight is recognized as one of the criteria of metabolic syndrome in non-obese individuals. AIM OF THE STUDY: The percentage of academic youth aged 19-25 years born with low birth weight was evaluated. MATERIAL AND METHODS: 146 students (52% women and 48% men) of Warsaw higher schools took part in the study. Data of birth parameters and gestational age (GA, weeks) were gained from the medical documentation retrospectively. Infant's mass ≤2999 g was recognized as decreased birth weight (LBW group). Body height and body mass, waist and hip circumferences were measured. WHR was calculated as well. Bioimpedance method was used to evaluate the body composition, height and weight were standardized using data for 18-year-old women and men from Warsaw population. RESULTS: Decreased birth weight has been identified in 18% studied population - LBW group: 65% women and 35% men. It has been shown that students with low birth weight were characterized by a significantly lower body height (-0.22±1.14 v. 0.38±1.02 SDS) and body mass (-0.11±1.15 vs. 0.70±1.15 SDS) in comparison with individuals born with normal birth parameters. Body fat content in students of studied groups was similar. It has been noted that WHR index was significantly lower (p=0.0009) in men of LBW group than in those of NBW group. CONCLUSIONS: 1. Decreased birth weight appears more frequently among girls. It's suggested that MONW are more common in females. 2. The relationship between birth parameters and height and weight in adults was confirmed. 3. In young men distribution of body fat is associated with birth weight.

[Physical activity for young adults born with low body weight on the background of peers]. / Zawartosc tkanki tluszczowej w skladzie ciala mlodych doroslych urodzonych z obnizona masa ciala jest zalezna od poziomu aktualnej aktywnosci fizycznej.

INTRODUCTION: Low birth parameters are associated with an increased risk of insulin resistance, type 2 diabetes, glucose intolerance and hypertension at later life. Regular physical activity can counteract these metabolic disorders. THE AIM OF THE STUDY: We determined the relation of the declared physical activity and body composition in young adults with respect to their birth weight. MATERIAL: A total of 156 subjects (52% women and 48% men) took part in the study (the average age 20.6±1.2 years). Participants who declared regular physical activity (minimum 3 times per week) were included in group I (n=66), others in group II (n=99). In each group, the percentage of people with small (SBW) and normal (NBW) birth weight was assessed. METHODS: Information about birth parameters and duration of pregnancy was obtained from medical records. Infant's mass ≤2999 g was recognized as small birth weight. Body height, body weight, waist and hips circumferences and body composition by BIA were measured. Frequency of physical activity was determined during an interview. RESULTS: Percentage of participants with small birth weight was respectively 17% in group I and 21% in group II. In group I standardized body height was significantly lower in subjects with SBW in comparison with those with NBW. Participants from group II with SBW had markedly lower standardized body weight and standardized BMI than adults with NBW. Independently of birth weight physically active persons characterized higher WHR values than their non active counterparts. Body fat content was significantly lower in group I (both in participants with SBW and NBW). Women and men from group I with SBW had also higher fat free mass in comparison with those from group II. CONCLUSIONS: Body fat content in young adults with small birth weight is related to their physical activity. People who regularly exercise had lower fat mass in comparison with non exercising ones. This is the confirmation of a protective influence of physical activity.

Plasma TBARS, blood GSH concentrations, and erythrocyte antioxidant enzyme activities in regularly menstruating women with ovulatory and anovulatory menstrual cycles.

BACKGROUND: Vigorous physical activity and subsequent depressed ovarian hormone secretion resulting in anovulatory menstrual cycles can affect erythrocyte antioxidant system in premenopausal women and contribute to attenuated protection against oxidative stress. METHODS: A total of 17 regularly menstruating women participated in the study. Prospective subjects monitored their basal body temperature (BBT) for 3 months prior to the study. Plasma progesterone concentration was assayed between the 7th and 9th day and again between the 22nd and 25th day of the menstrual cycle and made possible the classification of participants as either ovulating or non-ovulating. Plasma 17-beta-estradiol concentration was determined on the same menstrual cycle days as progesterone. Plasma thiobarbituric acid-reacting substances (TBARS) served as an index of plasma lipid peroxidation. Whole blood-reduced glutathione (GSH) concentration and glutathione peroxidase (GSH-PX) activity and erythrocyte catalase (CAT), superoxide dismutase and glutathione reductase (GSH-RX) represented red cells antioxidants. RESULTS: In non-ovulating women, the lack of progesterone peak between the 22nd and 25th day of the menstrual cycle was demonstrated. In addition, markedly lower (P<0.008) plasma 17-beta-estradiol concentrations in non-ovulating females than in ovulating ones in the follicular phase was noted. In the luteal phase, plasma 17-beta-estradiol levels in non-ovulating subjects tended to be lower (P<0.06) than in ovulating counterparts. Mean concentrations of plasma thiobarbituric-reacting substances and blood-reduced glutathione and mean activities of glutathione reductase, glutathione peroxidase and catalase did not differ significantly in ovulating and non-ovulating women. In non-ovulating women, both between the 7th and 9th day and the 22nd and 25th day of the menstrual cycle, erythrocyte superoxide dismutase (SOD) activity was higher (P<0.02) than in their ovulating counterparts. In ovulating subjects, significant and inverse correlation was demonstrated between circulating estradiol and SOD activity in collected data from both follicular and luteal phases. CONCLUSIONS: Current results indicate that persistent ovarian hormone disturbances in regularly menstruating women, and resultant anovulation did not affect plasma lipid peroxidation and GSH-dependent erythrocyte antioxidant defense. However, lower plasma estradiol concentrations resulted in attenuated erythrocyte SOD inhibition and elevated enzyme activity. The mechanism of inhibitory estradiol action on erythrocyte SOD activity as well as the importance of this effect for antioxidant protection merits further studies.