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.

Abstract Study aim: Our study was undertaken to analyze agreement between measured body fat and different indices of fatness in students of both sexes and with different physical activity. Materials and methods: A total of 330 students not engaged in regular physical activity (150 males and 180 females) and 356 students (180 males and 176 females) engaged in regular physical activity due to their study program (5–7 h/week) were recruited. In all participants body adiposity was measured from skinfold thickness. In addition, calculated indices of fatness based on waist (WC) and hip circumference (HC), such as abdominal volume index (AVI), body adiposity index (BAI) and relative fat mass (RFM) were calculated. Results: The analysis of Bland-Altman plots revealed that agreement between measured and calculated body fat was found for RFM and BAI in sedentary and active men and for BAI in sedentary women, but not for measured body fat and RFM in sedentary women and for RFM and BAI in active women. Discussion: Our study showed that in young adult Poles of both sexes and with different physical activity, the calculated obesity rates should be used with caution, especially in women, as an indicator of total body fat.

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.

Abstract Study aim: Numerous data have indicated that body fat stores undergo complicated regulation by genetic and environmental factors, including physical activity. However, the majority of studies did not take into account this aspect of lifestyle in proposed body fat limits. In this context it seems that a more precise and reliable classification of body fat is provided by the American Council on Exercise (ACE), which distinguishes individuals not only with respect to sex but also activity level. Material and methods: A total of 793 students (312 sedentary and 481 active) volunteered to participate in the study. Among sedentary participants 147 were male and 165 female. Among active subjects 206 were male and 275 were female. Active subjects were engaged in different modes of physical activity according to the study program. In all participants body mass index (BMI) was calculated. In participants with BMI 18.5–24.9 and BMI ≥ 25 body fat was determined using four skinfold measurements. Thereafter participants were classified according to the percentage of body fat using ranges for males and females provided by the American Council on Exercise (ACE) (essential fat, athletes, fitness, average and obese fatness). Results: None of the sedentary and active males with BMI 18.5–24.9 had high (obese) fat. In contrast, in sedentary males with BMI ≥ 25 16.4% were obese vs. 1.8% of obese active ones. In sedentary females BMI from 18.5 to 24.9 did not exclude obesity, which was found in 16.9% of participants. In sedentary females with BMI ≥ 25 most of the subjects (97.1%) were obese. In contrast, in active females with BMI ≥ 25 a similar percentage of participants had average and obese fat (53.3% and 46.7, respectively). Discussion: Our study clearly demonstrated that BMI as a simple measure of body composition provides false information concerning true adiposity in physically active male and female students. A similar BMI did not exclude marked differences in the percentage of body fat in sedentary and active students.

Background Our study was aimed at the evaluation of relationships between thyroid stimulating hormone (TSH) within the normal range and metabolic risk factors (glucose, insulin, HOMA-IR and lipoprotein profile) in physically active male and female students. Methods In 112 male and 107 female students circulating TSH, glucose, insulin and lipoproteins (triacylglycerols, total cholesterol, HDL-cholesterol and LDL-cholesterol) were measured in blood under fasting conditions. Insulin resistance was expressed as HOMA-IR. For further procedures 99 males and 97 regularly menstruating females with TSH 0.4 – 4.0 µIU/ml were accepted. Results In male students no correlations between circulating TSH, anthropometric and biochemical variables were noted. In females TSH within the normal range was slightly but significantly correlated with the triglyceride (TG) level (p<0.03). However, step-wise multiple regression analysis revealed that the effect of TSH was small (p<0.046) in relation to that found for HOMA-IR (p<0.0009). No relationships between biochemical variables and normal levels of TSH were noted in male students. However, surprisingly normal range TSH in males was slightly but significantly correlated with the percentage of body fat and this issue needs further studies concerning measurements of different fat depots.Conclusions The above data suggests that in active females TG synthesis and export from the liver is more sensitive to TSH action than in active male counterparts.

Background. Metabolic changes induced by combined oral contraceptives (COC) use is regularly active in females. Objectives. Analyzing blood cortisol and other biochemical variables in active (COC) users and non-users. Methods. A total of 123 active female students (25 COC users and 98 non-users) volunteered to participate in the study. The COC users declared 2-3 years of using different types of combined the fourth generation COC pills. In all participants' body composition, physical activity and dietary habits were determined. Circulating cortisol and insulin were determined using standard radioimmunoassay techniques. Plasma glucose and lipoproteins were determined using colorimetrical methods. To evaluate the health risk ratio of total cholesterol to HDL-cholesterol (Castelli index I) and LDL-cholesterol to HDL-cholesterol (Castelli index II) were calculated. Results. There were no between-groups differences in body composition and dietary habits. The COC users had markedly elevated plasma cortisol (p < 0.001), triacylglycerols (TG) (p < 0.001), total cholesterol (TC) (p < 0.002) and HDL-C (p < 0.040) with no effect on glucose, LDL-cholesterol (LDL-C) and TC-to HDL-C ratio. In contrast, the LDL-C to HDL-C ratio in COC users was lower vs. non-users (p < 0.002). COC users were characterized by a higher frequency of elevated TC (p < 0.001) and HDL-C (p < 0.040). However, in all participants Castelli index I and II were within the accepted limits suggesting a low risk of cardiovascular disease. Conclusion. In COC users regular physical activity does not prevent changes in circulating biochemical variables, however, these changes did not affect cardiovascular risk which is low and similar to that noted in active non-users.

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.

BACKGROUNDAn 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.METHODSThe 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).RESULTSStudied 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.CONCLUSIONSRelatively 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.

Summary Study aim: The aim of the study was to evaluate the relationship between low birth mass and concentration of high-sensitivity C-reactive protein (hsCRP) as a cardiovascular risk factor in young women with various levels of physical activity. Materials and methods: 102 female students aged 19.7 ± 0.8 (18.6-23.0) were included. The study group was divided according to the declared physical activity: high physical activity (HPA, n = 69) and low physical activity (LPA, n = 33). Anthropometric indices were measured: body mass, height, hip and waist circumference. hsCRP levels were obtained from venous blood samples. Birth body mass (BBM) and birth height were collected from medical documentation. Results: Women with low BBM and LPA had a significantly higher concentration of hsCRP than women with low BBM and HPA, as well as women with normal BBM. Conclusions: Low birth mass together with low physical activity is a strong predictor of raised concentration of hsCRP, which correlates with an increased risk of cardiovascular and metabolic diseases. Regular physical activity in women with low birth mass may prevent an increased hsCRP concentration, and as a result decrease the risk of cardiovascular and metabolic diseases.

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.

Summary Study aim: To evaluate energy, macronutrient, calcium, magnesium, and phosphate daily intake in young healthy Polish male students. Material and methods: Two hundred and sixteen participants were physical education students engaged in regular physical ac­tivity (about 9 h/week) and were recognized as physically active. One hundred and fourteen students were from other speciali­zations participating in 1.5 h/week gymnastics classes and were recognized as sedentary. Body mass and height were measured using standard medical equipment. Body fat was evaluated from four skinfold measurements. In all subjects daily intake of energy, protein, fat, carbohydrates, calcium, magnesium and phosphate was briefly assessed from 24-hour food records taken over 4 days. Results: The active students’ diet was characterized by significantly higher energy, macronutrient and mineral daily intake. Moreover, calcium to phosphorus and calcium to magnesium ratios in active subjects were higher than in sedentary ones. There was no significant difference between groups in protein or magnesium intake expressed per 1000 kcal. In contrast, daily intake of fat and phosphate expressed per 1000 kcal was significantly lower in the active students vs. sedentary ones (p < 0.001 and p < 0.05 for fat and phosphate, respectively). Active students were characterized by significantly higher carbohydrate and cal­cium intake per 1000 kcal in comparison with their sedentary counterparts (p < 0.001 for both variables). Conclusions: The dietary pattern of active students was found to be slightly but significantly better than that of their sedentary counterparts. However, in both groups it was far from being a healthy one.

BACKGROUND: Muscle strength depends among other factors on its length, i.e., the angular position of the joint it spans. However, these relationship is often neglected in the construction of training machines.OBJECTIVE: The aim of this study was to verify the effectiveness of a variable-cam during strength training.METHODS: Thirty-two men divided into two groups participated in an 8-week intensive strength training of elbow flexors. One group (C) trained on a machine with a cam developed in the shape corresponding to the strength change characteristics of flexor muscles as a function of the angular position in the elbow joint. The second group (D) trained on a machine with a disc plate. The effects of the training were evaluated on the basis of changes in the value of PT measured under isokinetic conditions, anthropometric parameters, and CK activity.RESULTS: After the end of the training, a significant increase in the values of the PT and anthropometric parameters were observed only in group C. Weekly changes of CK activity appeared only in the group exercising with a cam, while in the group exercising on the machine with a disc plate, the two-day rest turned out to be too short for the elimination of the CK molecules from the blood to occur.CONCLUSIONS: Strength training using a machine with a muscle-specific adjusted cam is especially effective in the case of the elbow flexors.

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.

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.

Physical activity induces changes in the endocrine system. Previous data indicated that changes in insulin secretion and the tissue response to this hormone are very important for energy metabolism. It is believed that they are accompanied by changes in lipid metabolism, but factors contributing to this process are still disputed. The aim of this study was to assess interactions among insulin sensitivity, thyroid function, a bone turnover marker and serum lipid profile in young physically active men. Eighty-seven physical education students, aged 18-23 years, participated in the study. We measured serum levels of glucose, lipids, insulin, thyroid-stimulating hormone (TSH), osteocalcin and anthropometric parameters. Insulin sensitivity was determined using homeostatic model assessment for insulin resistance (HOMA-IR). The median value of HOMA-IR (1.344) was used to divide the study population into Group A (above the median) and Group B (below the median). Men from both groups did not differ in anthropometric parameters or in daily physical activity. Triglycerides (TG), total cholesterol (TC) and high-density lipoprotein cholesterol (HDL-C) levels were higher in Group A (P<0.05). TSH and osteocalcin levels were similar in males with different HOMA-IR. Multiple regression analysis for TSH and osteocalcin showed that in Group A these hormones had no effect on plasma lipoproteins. However, in Group B they significantly determined the variation of plasma TC and low-density lipoprotein cholesterol (LDL-C) levels (in about 28% and 29%, respectively). We concluded that TSH and osteocalcin are involved in determination of a more healthy lipid profile at a certain level of insulin sensitivity.

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.

1. Hedley AA, Ogden CL, Johnson CL, et al. Prevalence of overweight and obesity among US children, adolescents and adults, 1999–2002. JAMA 2004; 291: 2847–2850. CrossRef Google Scholar

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.

Summary Introduction. The physiological demands of a judo match strain both anaerobic and aerobic systems. The purpose of the present study was to examine the effect of five weeks of training during a preparatory period on anaerobic and aerobic performance of well trained male judokas. Material and methods. The subject of the present study were nine male judo athletes, members of a collegiate team. Before and after five-week training, all participants performed a graded exercise test on the treadmill for the determination of anaerobic threshold and the 30 s Wingate test for lower body. After each workload, the capillary blood from finger tips was taken for lactate determination during incremental exercise and 5, 7, 9, 11, 13, and 30 minutes after cessation of the 30 s Wingate test. Results. Five-week training period resulted in statistically significant increase of velocity at anaerobic threshold (VAT), determined in a graded exercise test. The peak power, in terms of relative (W/kg) values, measured in the Wingate test for lower body, was similar before and after the five-week training period, however the relative mean power was significantly higher after this training period finished. The blood lactate concentration, 30 minutes after cessation of the Wingate test, was significantly lower after the five weeks of training in comparison with the values before training. Conclusions. The obtained data shows that the five-week preparatory training period resulted in the increase of aerobic fitness of male judo athletes. The results of the current study in well trained male judokas may provide useful information for coaches and trainers in optimizing training programs.

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.