A criterion-referenced assessment is needed for measuring child obesity.

Body Mass Index (BMI), as an adiposity indicator, assumes that for any given height a change in weight is attributed to a change in fat. This seems problematic in growing youth as great divergence is evident in bone, muscle, and adipose tissue development. Secondly, use of reference populations in categorizing children based on BMI, frequently use arbitrary percentile cut-offs for obesity and do not meet all of the assumptions that cut-offs imply. Lastly, BMI does not control for maturation status. Criterion-referenced assessments of child obesity that account for abdominal adiposity and permit international comparisons, such as waist-to-height ratio (WtHR), must be considered. Better predictive utility has been demonstrated when using WtHR for abdominal adiposity and cardiovascular risk factors in youth compared with BMI. Although multiple methods for assessing waist circumference may be problematic for comparison purposes, its simplicity and international comparability aspects make it a promising alternative to BMI.

A consideration of the paradigm of exercise physiology.

Exercise physiology, in terms of the history of biological sciences, is quite young and has a rather tumultuous history - as it spans physical education, health & medicine, sport science, and biology. This has led to the development of differing definitions, research approaches, practices and goals. This is easily seen in the presence of competing and non-universally adopted definitions of fitness. Such internal inconsistencies portray to the outside world a discipline experiencing the problems associated with a changing paradigm. Every science requires the presence of a paradigm that both describes and guides the evolution of thinking, experimentation, and the application of such. It is argued here that exercise physiology has been operating without benefit of a satisfactory and relevant paradigm. A further proposition is that the required disciplinary definitions derived from an articulated paradigm are also absent. A paradigmatic scheme based on biological dogma is presented along with proposed definitions.

Snatch technique of United States national level weightlifters.

This study analyzed the top 3 successful snatch attempts by individual lifters in each weight class at a U.S. National Championship weightlifting meet. Two-dimensional (2-D) body position and characteristics of the lifts were compared via 2D video analysis in groups of lifters who displaced forward, showed no displacement, or displaced backward to receive the bar. No significant group differences (p > 0.05) were noted for body mass, bar mass, or hip angle. The rearward displacement group had a significantly greater horizontal distance between the shoulder and heel at the end of the pull (determined as the point where the bar ceases to accelerate vertically). Hip angles for the no displacement group had a small-to-moderate effect size (0.50) in comparison to the forward displacement group, but they only showed a small effect size (0.17) when compared with the rearward displacement group. The forward displacement group showed a small-to-moderate effect size compared with both the no displacement group (0.51) and the rearward displacement group (0.55) concerning the horizontal distance from the shoulder to the heel. These data seem to suggest that rearward displacement in the drop-under phase in the snatch is not detrimental to performance and actually seems to be a preferred technique in U.S. national level lifters. In addition to evidence that rearward displacement is exhibited in elite lifters and is coached globally, it seems this is the preferred technique in international competitions. This technique may be considered a viable variation of the snatch by coaches and athletes of all levels.

Upper-body anthropometric and strength measures and their relationship to start time in elite luge athletes.

Start time has been shown to be a significant predictor of overall performance in the sport of luge. The starting motion in luge has been described as an explosive upper-body movement that requires significant technique and skill to perfect. This study aims to investigate upper-body factors that may relate to start time in luge. Twenty-two subjects participated in the study as part of their normal off-season training. Each subject had a minimum of 3 years' experience in the sport of luge, and at the time was a member of a U.S. Luge National Team. Subjects completed a 1 repetition maximum (1RM) in the bench press (BP), prone row (PR), and weighted pull-up (WP). Anthropometric distances were taken measuring finger-tip span (FS), biacromial breadth (BB), acromio-radial length, acromio-olecranon length (AO), hand length, and sitting cervical height. Subjects were divided into 2 groups based on which U.S. Luge National team they were currently a member of, Senior National (SN, n = 13) and Junior National (JN, n = 9). A Pearson product-moment correlation coefficient showed several significant (p ≤ 0.05) relationships between upper-body variables and start time among the groups. The BP and PR 1RM were shown to have a significant relationship in both groups. Among the anthropometric variables, AO was also significant in both groups. The WP, FS, BB, and height were all shown to have a significant relationship with start time in the SN group, but not in the JN group. These results suggest that as luge athletes become more efficient in the starting technique, outside factors such as upper-body strength and anthropometric measures play a larger role in performance.

Determination of ventilatory threshold through quadratic regression analysis.

Ventilatory threshold (VT) has been used to measure physiological occurrences in athletes through models via gas analysis with limited accuracy. The purpose of this study is to establish a mathematical model to more accurately detect the ventilatory threshold using the ventilatory equivalent of carbon dioxide (VE/VCO2) and the ventilatory equivalent of oxygen (VE/Vo2). The methodology is primarily a mathematical analysis of data. The raw data used were archived from the cardiorespiratory laboratory in the Department of Kinesiology at Midwestern State University. Procedures for archived data collection included breath-by-breath gas analysis averaged every 20 seconds (ParVoMedics, TrueMax 2400). A ramp protocol on a Velotron bicycle ergometer was used with increased work at 25 W.min beginning with 150 W, until volitional fatigue. The subjects consisted of 27 healthy, trained cyclists with age ranging from 18 to 50 years. All subjects signed a university approved informed consent before testing. Graphic scatterplots and statistical regression analyses were performed to establish the crossover and subsequent dissociation of VE/Vo2 to VE/VCO2. A polynomial trend line along the scatterplots for VE/VO2 and VE/VCO2 was used because of the high correlation coefficient, the coefficient of determination, and trend line. The equations derived from the scatterplots and trend lines were quadratic in nature because they have a polynomial degree of 2. A graphing calculator in conjunction with a spreadsheet was used to find the exact point of intersection of the 2 trend lines. After the quadratic regression analysis, the exact point of VE/Vo2 and VE/VCO2 crossover was established as the VT. This application will allow investigators to more accurately determine the VT in subsequent research.

Force-time curve characteristics and hormonal alterations during an eleven-week training period in elite women weightlifters.

The purpose of this investigation was to study the effects of an 11-week training period performed by female weightlifters. Two weeks before this investigation, baseline measures for total testosterone, cortisol, and testosterone:cortisol ratio were collected. The 11-week training program consisted of the core exercises (i.e., clean, clean and jerk, and snatch) and other supplemental exercises (i.e., clean pull, snatch pull, squat, and front squat). Hormonal, isometric, and dynamic middle thigh pull force-time curve characteristics were assessed biweekly throughout the duration of the investigation, whereas volume load and training intensity were assessed weekly throughout the investigation. The testosterone:cortisol ratio of the baseline (1.19 +/- 0.64) was significantly different from the ratio of weeks 1 (0.67 +/- 0.36) and 9 (0.94 +/- 0.66). When the week-to-week values were compared, week 1 (0.67 +/- 0.36) was significantly different (P < 0.05; eta = 0.84) from week 3 (1.06 +/- 0.54). A very strong correlation (r = -0.83; r = 0.69) was found between the percentage change of the testosterone:cortisol ratio and volume load from weeks 1 to 11. Moderate to very strong correlations were noted between the percentage change in volume load and isometric peak force, peak force during the 30% isometric peak force trial, and peak force during the 100-kg trial during the 11 weeks of training. The primary finding of this study was that alterations in training volume load can result in concomitant changes in the anabolic-to-catabolic balance, as indicated by the testosterone:cortisol ratio, and the ability to generate maximal forces.

Comparisons between twice-daily and once-daily training sessions in male weight lifters.

CONTEXT: Many elite athletes use increased daily training frequencies as a means to increase training load without substantial published literature to support this practice. PURPOSE: To compare the physiological responses to twice- and once-daily training sessions with similar training volumes. METHODS: Ten nationally competitive male weightlifters (age 20.5 +/- 1.2 y, body mass 92.9 +/- 23.6 kg, training history 5.5 +/- 1.5 y) were matched on body mass and training experience, then randomly assigned to train either once or twice daily for 3 wk. Isometric knee-extension strength (ISO), muscle cross-sectional area, vertical-jump peak power, resting hormone concentrations, neuromuscular activation (EMG), and weightlifting performance were obtained before and after the experimental training period. RESULTS: All dependent measures before the training intervention were similar for both groups. A 2-way repeated-measures ANOVA did not reveal any significant main effects (group or trial) or interaction effects (group x trial) for any of the dependent variables. There were also no significant group differences when parameters were expressed as percentage change, but the twice-daily training group had a greater percentage change in ISO (+5.1% vs +3.2%), EMG (+20.3% vs +9.1%), testosterone (+10.5% vs +6.4%), and testosterone:cortisol ratio (-10.5% vs +1.3%) than did the once-daily training group. CONCLUSIONS: There were no additional benefits from increased daily training frequency in national-level male weightlifters, but the increase in ISO and EMG activity for the twice-daily group might provide some rationale for dividing training load in an attempt to reduce the risk of overtraining.

Force-time curve characteristics of dynamic and isometric muscle actions of elite women olympic weightlifters.

Six elite women weightlifters were tested to evaluate force-time curve characteristics and intercorrelations of isometric and dynamic muscle actions. Subjects performed isometric and dynamic mid-thigh clean pulls at 30% of maximal isometric peak force and 100 kg from a standardized position on a 61.0 x 121.9 cm AMTI forceplate. Isometric peak force showed strong correlations to the athletes' competitive snatch, clean and jerk, and combined total (r = 0.93, 0.64, and 0.80 respectively). Isometric rate of force development showed moderate to strong relationships to the athletes' competitive snatch, clean and jerk, and combined total (r = 0.79, 0.69, and 0.80 respectively). The results of this study suggest that the ability to perform maximal snatch and clean and jerks shows some structural and functional foundation with the ability to generate high forces rapidly in elite women weightlifters.

Severity of viral infection is promoted by hyperthermic pretreatment.

The aim of this study was to determine if prior heat shock and consequential heat shock protein (HSP) accumulation would inhibit viral infection. Confluent cultures of Madin-Darby bovine kidney cells were subjected to 30 mins of hyperthermia at 42 degrees C then allowed to recover at 37 micro C for six hrs. During the six hrs, HSP concentrations increased by 232% in heat-shocked cultures. Following the recovery period, six replicates of heat-shocked (HS) and six replicates of non-heat-shocked (CON) cultures were infected with Bovine Herpes virus 1. After 72 hours, severity of infection was assessed by counting formed viral plaques in cell cultures. CON cultures averaged 172.0+/-34.3 plaques per culture and HS cultures averaged 339.3+/-96.1 plaques per culture, representing a significant increase in infected cells (p=0.0044). These data provide evidence that physiological stressors related to extreme or exhaustive exercise, specifically hyperthermia, may increase risk of viral infection.

Training alterations in elite cyclists may cause transient changes in glomerular filtration rate.

Training alterations in elite cyclists may cause transient changes in glomerular filtration rate. To these authors' knowledge, no biochemical investigation of chronic renal function in athletes during a training cycle exists. The purpose of the present archival study was to evaluate the effects of training on homeostatic renal function, evaluated predicted glomerular filtration rate (GFR). Eight male competitive college cyclists (mean ± SD: age: 22.2 ± 3.8 yrs, height: 1.80 ± 0.06 m, mass: 76.6 ± 7.9 kg, and body fat was 7 ± 2%) volunteered to undergo 12 weeks of training, and were required to undergo blood sampling at timed intervals to calculate GFR. Homeostatic GFR was altered significantly during various points in the investigation. Volume and average cycling speed were found to have moderate correlations to alterations in GFR. In addition to these findings, 7 of the 8 subjects had GFR's below normal physiological ranges during some point in the experiment. The duration, intensity, and volume of cycling appear to have an influence on renal function. This influence is pronounced during periods when the athletes are unaccustomed to the training load. Key PointsChronic cycling training is associated with alterations of glomerular filtration rate.Intensity of cycling exercise is associated with a reduction or resting glomerular filtration rate.Serum creatinine and serum urea nitrogen are not associated with changes in glomerular filtration rate in chronically exercising cyclists.

The effects of 8 weeks of creatine monohydrate and glutamine supplementation on body composition and performance measures.

Twenty-nine (17 men, 12 women) collegiate track and field athletes were randomly divided into a creatine monohydrate (CM, n = 10) group, creatine monohydrate and glutamine (CG, n = 10) group, or placebo (P, n = 9) group. The CM group received 0.3 g creatine.kg body mass per day for 1 week, followed by 0.03 g creatine.kg body mass per day for 7 weeks. The CG group received the same creatine dosage scheme as the CM group plus 4 g glutamine.day(-1). All 3 treatment groups participated in an identical periodized strength and conditioning program during preseason training. Body composition, vertical jump, and cycle performances were tested before (T1) and after (T2) the 8-week supplementation period. Body mass and lean body mass (LBM) increased at a greater rate for the CM and CG groups, compared with the P treatment. Additionally, the CM and CG groups exhibited significantly greater improvement in initial rate of power production, compared with the placebo treatment. These results suggest CM and CG significantly increase body mass, LBM, and initial rate of power production during multiple cycle ergometer bouts.

Effects of different set configurations on barbell velocity and displacement during a clean pull.

The effects of 3 types of set configurations (cluster, traditional, and undulating) on barbell kinematics were investigated in the present study. Thirteen men (track and field = 8; Olympic weightlifters = 5) (mean +/- SEM age, 23.4 +/- 1.1 years; height, 181.3 +/- 2.1 cm; body mass, 89.8 +/- 4.2 kg) performed 1 set of 5 repetitions in a cluster, traditional, and undulating fashion at 90 and 120% of their 1 repetition maximum (1RM) power clean (119.0 +/- 4.3 kg). All data were collected at 50 Hz and analyzed with a V-Scope Weightlifting Analysis System. Peak velocity (PV) and peak displacement (PD) were analyzed for each repetition and averaged for each set type. Results indicated that a significantly (p < 0.016) higher PV occurred during the cluster set when compared with the traditional sets at both intensities. PD was significantly higher than traditional sets at the 120% intensity. The present study suggests set configuration can affect PV and PD during clean pulls.

Serum chemistry and hematological adaptations to 6 weeks of moderate to intense resistance training.

This study examined immune cell and blood chemistry changes occurring in trained weightlifters after 1 week of rest followed by 6 weeks of Olympic-style resistance exercise. Blood was drawn weekly after 1 day of rest at the same time and on the same day of the week for 7 weeks. Lymphocyte numbers increased in weeks 5 through 7. Sodium concentration rose above entry levels in week 2, remained elevated, and peaked in week 5. Direct bilirubin dropped below baseline values in the final week. Chloride and alkaline phosphatase concentrations increased as training progressed. Chloride, potassium, albumin, CO(2), and alkaline phosphatase concentrations peaked in weeks 4 through 6. Serum creatinine was elevated in weeks 2 through 5. Data indicate that resistance training induces changes in immune cell count and blood chemistry that remain within, or near, normal clinical values. It appears that resistance training does not induce immunosuppression or negatively affect hepatic or renal function.

Induction of mitochondrial stress proteins following treadmill running.

PURPOSE: The purpose of this investigation was to examine the relationship between the expression of HSP60 and GRP75 and the oxidative potential of skeletal muscle as assessed by the citrate synthase activity following endurance training to sedentary controls. METHODS: Female Wistar rats were assigned to one of two groups: sedentary controls (N = 8) or endurance trained (N = 9). Endurance trained rats were run 60 min x d(-1) at 27 m x min(-1) up a 10% incline 6 d x wk(-1) for 8 wk on a motor-driven treadmill. RESULTS: Training produced a 47% increase in citrate synthase activity along with a 103% increase in the expression of HSP60 and a 105% increase in the expression of GRP75 in plantaris muscle. In addition, there was a significant correlation between the citrate synthase activity and expression of HSP60 found in plantaris muscle. CONCLUSIONS: These findings are consistent with the hypothesis that the adaptive response to treadmill running may require elevations in the expression of HSP60 and GRP75 to support protein import and folding.

Temporal and spatial expression of the period gene in the reproductive system of the codling moth.

The authors examined patterns of spatial and temporal expression of Drosophila per gene homologue in the codling moth, Cydia pomonella. Since sperm release in moths is regulated in a circadian manner by an autonomous clock that is independent from the brain, the authors investigated per expression in male reproductive system along with its expression in moth heads. per mRNA is rhythmically expressed with the same phase and amplitude in both tissues under light-dark (LD) conditions. The levels of per mRNA are low during the day, start to increase before lights-off, reach the peak in dark, and decrease after lights-on. In constant darkness (DD), cycling of per mRNA continued in heads with severely blunted amplitude. No cycling of per mRNA was detected in testis in DD. In situ hybridization and immunocytochemistry revealed distinct spatial patterns of per expression in the moth reproductive system. There is no expression of per in cells forming the wall of testes or in sperm bundles. However, per mRNA and protein are rhythmically expressed in the epithelial cells forming the wall of the upper vas deferens (UVD) and in the cells of the terminal epithelium, which are involved in the circadian gating of sperm release. Increase in per mRNA in the UVD coincides with sperm accumulation in this part of the insect reproductive system.

Ablation of posterior atrial ganglionated plexus potentiates sympathetic tachycardia to behavioral stress.

The role of the posterior atrial ganglionated plexus (PAGP) in heart rate (HR) control was tested in unanesthetized dogs (n = 8). Resting HR was unchanged before (85 +/- 20 beats/min, mean +/- SD) versus after (87 +/- 18 beats/min) surgical ablation of these intrinsic cardiac ganglia (PAGPX). However, the peak tachycardia to a 30-s stressful stimulus was significantly increased (P < 0.05) from +53 +/- 22 beats/min before the denervation to +77 +/- 13 beats/min after PAGPX. Conversely, the peak HR increase during the stress after beta-adrenergic blockade was the same before (36 +/- 24 beats/min) versus after (38 +/- 14 beats/min) PAGPX. Moreover, the HR response to a neutral behavioral stimulus, which is mediated primarily by withdrawal of parasympathetic inhibition of the sinoatrial (SA) node, was unaltered by PAGPX. Thus the augmented tachycardia subsequent to PAGPX was attributable primarily to increased sympathetic action at the SA node. These findings indicate that a major role of PAGP parasympathetic neurons is to inhibit sympathoexcitatory effects on HR, probably either via interactions between neurons comprising the intrinsic plexus(es) or perhaps via presynaptic inhibition of sympathetic neurotransmitter release. This organization would allow parasympathetic ganglia within the PAGP to selectively modify sympathetic input to the SA node independent of direct vagal inhibition of pacemaker activity.

Physical activity, muscle, and the HSP70 response.

Selye (1936) described how organisms react to various external stimuli (i.e., stressors). These reactions generally follow a programmed series of events and help the organism adapt to the imposed stress. The heat shock response is a common cellular reaction to external stressors, including physical activity. A characteristic set of proteins is synthesised shortly after the organism is exposed to stress. Researchers have not determined how heat shock proteins affect the exercise response. However, their role in adaptation to exercise and training might be inferred, since the synthetic patterns correlate well with the stress adaptation syndrome that Selye described. This review addresses the 70 kilodalton heat shock protein family (HSP70), the most strongly induced heat shock proteins. This paper provides an overview of the general heat shock response and a brief review of literature on HSP70 function, structure, regulation, and potential applications. Potential applications in health, exercise, and medicine are provided.

Autonomic nervous control of heart rate orienting and alpha responses in dog.

The object of this experiment is to study the autonomic nervous control of alpha responses elicited in classical conditioning. Twenty-two mongrel dogs were trained in classical discriminative conditioning. Typical two-phase tachycardic responses were observed in positive (CS+) trials while only the earliest, phase 1, response was observed in negative (CS-) trials. The phase 1 response, which was identical in CS+ and CS-trials, was compared in dogs before and after selective SA-nodal parasympathectomy (N = 7) and beta-adrenergic blockade (N = 11). The phase 1 tachycardic response was eliminated by selective SA-nodal parasympathectomy but not by beta-adrenergic blockade. We conclude that the phase 1 response observed in both CS+ and CS-trials with similar time sequence and magnitude is an alpha response. The heart rate orienting response results from a withdrawal of parasympathetic activity with little or no change in sympathetic tone.

Metabolism, uptake, and excretion of a D-glucaric acid salt and its potential use in cancer prevention.

D-Glucaric acid (GA) is a nontoxic, natural compound. One of its derivatives is the potent beta-glucuronidase inhibitor D-glucaro-1,4-lactone (1,4-GL). The goal of this study was to demonstrate the in vivo formation of 1,4-GL from a D-glucarate salt and determine its metabolism, uptake by selected organs, and excretion following oral administration of potassium hydrogen D-[14C]glucarate to male and female Sprague-Dawley rats. 1,4-GL increases detoxification of carcinogens and tumor promoters/progressors by inhibiting beta-glucuronidase and preventing hydrolysis of their glucuronides. 1,4-GL and its precursors, such as potassium hydrogen D-glucarate and calcium D-glucarate, may exert their anticancer action, in part, through alterations in steroidogenesis accompanied by changes in the hormonal environment and the proliferative status of the target organ. Thus, GA derivatives may be useful as new or adjuvant cancer preventive and therapeutic agents. In our study, 1,4-GL was found to be formed from the D-glucarate salt in the stomach of rats. It was apparently absorbed from the gastrointestinal tract, transported with the blood to different internal organs, and excreted in the urine and to a lesser extent in bile. There were no significant differences in the metabolism of PHG between male and female rats. Thus, formation of 1,4-GL from D-glucaric acid derivatives may be prerequisite for their inhibition of chemical carcinogenesis in rodents and prevention of breast, prostate, and colon cancer in humans.

Regional distribution of HSP70 proteins after myocardial infarction.

Hypoxia and altered hemodynamic status, both components of myocardial infarction, have been shown to be potent inducers of the 70 kD family of heat shock proteins (HSP70). We hypothesized that after infarction, the surviving myocardium would synthesize HSP70 proteins in a temporally and regionally distinct pattern. We believed that there would be a lack of an HSP70 response in the infarcted area (I), reflecting the loss of viable cells. We further postulated that tissues bordering infarctions (M) would have a compromised HSP70 response. Conversely, we proposed that HSP70 would be induced in septal tissues (S) of the infarcted heart, as a hypertrophic adaptation. A rat model of myocardial infarction was used to examine the changes in relative concentration and distribution of three major HSP70 family proteins; cytoplasmic HSP72, mitochondrial HSP75, and endoplasmic reticular GRP78 (glucose regulated protein) during 21 days of recovery. While all three HSP70 family proteins investigated were detected in all hearts from all groups at all time periods, experimental treatment (infarction) induced changes in relative protein concentrations that varied with time and sample site location. Relative concentrations of HSP72 and GRP78 were unchanged in the 24 h following infarction while relative HSP75 concentrations were halved in M tissues during the same time period. Between days 5 and 7, several changes were noted. M samples displayed nearly twice the relative concentrations of HSP75 and GRP78 after infarction, but showed no change in HSP72. S tissues showed two-fold or larger increases in all three HSP70 family proteins. I samples showed unanticipated increases in HSP75 and GRP78 during this time period. After 14 to 21 days of recovery, HSP70 family protein concentration levels in M, S, and I tissues from infarcted hearts had returned to levels similar to those seen in control animals. We conclude that the myocardium is unable to, or does not, mount an immediate HSP70 response after infarction but does recover such activity by 5-7 days after infarction.