Modulation of synaptic plasticity by short-term aerobic exercise in adult mice.

Physiological effects of different types, of continuous and interval aerobic training, have been largely described and studied in the adult man. It was previously indicated that interval training plays an important role in maximizing both peripheral muscle and central cardiorespiratory adaptations, permitting significant functional improvement even in healthy sedentary subjects. Since the outcome of different aerobic training trials on cognitive processes had never been evaluated, we compared, on an experimental mouse model, the effects of four training exercise protocols, named respectively C100, I100, C50 and I50 depending on the volume and on the type of training proposed, continuous or interval method. Therefore, to asses quantitative and qualitative functional changes, we analyzed several physical parameters before and after 6 weeks training in all four groups with respect to the control sedentary animals and we studied synaptic plasticity, by extracellular in vitro recordings, in hippocampal mouse slices, a region involved in learning and memory processes. We found that all four protocols of exercise applied in this study exerted positive effects on both physical and training parameters inducing weight augmentation, strength endurance and aerobic endurance increase, and potentiation of motor coordination. However, the improvement observed failed to induce an enhancement in synaptic plasticity in three out of four exercise protocols and only in the slices from mice trained with the interval 50% volume exercise the long term potentiation (LTP) increased with respect to the sedentary group. These findings suggest that motor activity exerts positive effects on cognitive processes provided that certain principles are respected, such as the training load and the elements of which it is composed, in order to plan the right quantitative and qualitative parameters and the appropriate recovery periods.

Water polo throwing velocity and kinematics: differences between competitive levels in male players.

AIM: In water polo, throwing is one of the most important and frequently used technical skills for the player. There is no scientific literature that provides information about differences in throwing between elite and sub-elite water polo players. The aim of our study was to study differences in throwing velocities and kinematic variables in elite and sub-elite level male water polo players. METHODS: We considered the variables under standardized conditions during a typical motion, the five-meter shot (penalty). Thirty-four athletes from the Men's First Division Water Polo Championship and forty-two players participating in the National Fourth Division League, took part in the study. Video analysis measures were taken with high-speed digital cameras and the videos were analyzed offline with Dartfish 5.0 Pro. RESULTS: No correlation was found between body mass, height and throwing velocity. Elite players had higher values ​for ball speed (22.8±2.4 m/s for elite team and 18.4±1.7 m/s for sub-elite team; P=0.002) and greater elbow angle (157.5±10.3 degree for elite team versus 146.7±8.9 degree for sub-elite team; P=0.002). In elite team the throwing time was lower (165.6±22.2 and 188.6±23.9 ms, respectively; P=0.05) and the shoulder angle was smaller (115.1±10.3 and 123.8±12.4 degree, respectively; P=0.03) than in sub-elite team. Head height was significantly greater in elite players (elite players 71.1±8.7 cm, sub-elite players 65.6±6.2 cm; P=0.03). CONCLUSION: Differences in kinematic characteristics between elite and sub-elite players were showed. Differences in elbow and shoulder action must be considered both in training and injury prevention.

Detraining in young soccer players.

BACKGROUND: Two types of detraining can be described: short-term detraining with a period of less than 4 weeks, and long-term detraining (period longer than 4 weeks). The purpose of this study is to verify the presence and eventually the magnitude of physiological cardiorespiratory changes in young team sport players after a period of long-term detraining. METHODS: Fourteen young soccer players (15 ± 1 year) were studied with two incremental tests at the end of the regular season and after a six-week total break period from training activities. Physiological variables were evaluated: heart rate (HR), oxygen uptake (VO2), volume of ventilation (VE), aerobic (VA) and anaerobic (Van) running speed at thresholds and maximum effort were recorded. RESULTS: This study shows the magnitude of the physiological changes in young players after a period of long-term detraining. The results showed significant decreases at the end of the detraining period of VO2 at VA of 22.7% (44.54 ± 4.56 vs. 34.41 ± 4.57 mL/kg/min, P<0.05), of 25.8% of VO2 at VAn (54.60 ± 5.81 vs. 40.48 ± 5.07 mL/kg/min, P<0.05) and of 21.2% in VO2 max (62.83 ± 5.77 vs. 49.46 ± 6.51 mL/kg/min, P<0.05). Speed at VA (11.5 ± 0.96 vs. 10.7 ± 0.97 km/h; P<0.05), speed at VAn (15.3 ± 1.05 vs. 14.2 ± 1.48 km/h; P<0.05), peak running speed (18.8 ± 1.20 vs. 17.2 ± 1.1 km/h; P<0.05). CONCLUSION: It is likely that alteration of metabolic parameters may significantly affect the range of physical condition and especially, aerobic-anaerobic resistance and maintenance training would be advisable in young athletes during the transition period. Given the relevance of worsening demonstrated by our data, coaches should avoid very long periods of complete rest (no more than 15 days) at the end of the season.

Descriptive study about congruence in wheelchair prescription.

AIM: Wheelchair prescription is relevant in the prevention of muscular joint pathology, and to facilitate autonomy and the patient's social life. However, in order to reach this goal, respecting the standards with a client-centred approach is essential. Congruence between user ability and wheelchair characteristics by making wheelchairs more "user friendly" can improve patient independence, facilitate integration into society and improve the patient's quality of life. The purpose of this study was to analyse congruence of wheelchair use by our patients, through the consideration of specific recommendations related to each subject's individual clinical situation. The second aim of the paper was to improve wheelchair prescriptions, by identifying the most frequent mistakes in the prescription and construction of wheelchairs. DESIGN: Observational study, outpatient. POPULATION: One hundred-fifty wheelchair users (average age 46.7±17.3) were analysed and described at 16.2±8.5 years from the onset of their disability. The subjects were 80 males and 70 females. RESULTS: Sixty-eight percent of the wheelchairs were not suitable for the patients, while 32% were suitable. We reported the incidence of non-congruence with respect to each wheelchair part. CONCLUSION: After finding a correlation between the prescription sources and suitability, the authors suggested that wheelchair prescriptions should be carried out in specialized departments, or that physician competences, and collaboration between physicians and technicians must be improved. Our data indicates the necessity to pay more attention to wheelchair prescription while considering ergonomic fitting to the individual. CLINICAL REHABILITATION IMPACT: Identifying the most frequent mistakes in the prescription and construction of wheelchairs in this paper could help to make more appropriate prescriptions.

Muscle fatigue induced by two different resistances: Elastic tubing versus weight machines.

Elastic tubes are devices relatively inexpensive, easy to use, portable and safe, which are claimed to provide advantages with respect to training with free weights or weight machine. The aim of this work was to assess neuromuscular modification induced by the use of two different muscle contraction modalities (elastic versus weight resistances) until exhaustion. Fourteen healthy physically active male students (age: 28±6 years; body mass 72.1±11.0kg; height: 173.5±6.9cm) were recruited. They were requested to reach exhaustion with dynamic contraction at 70% of their own One Repetition Maximal (1RM) using, in two different days and in random order, Thera Band® tubes or traditional weight plates on an arm machine designed and built for those tasks. Before and after such contractions a standardized fatiguing isometric test (3 Maximal Voluntary Contractions, MVC plus 60s at 60% MVC) was requested to assess differences induced by the exhaustion sessions. During fatiguing tests surface EMG signals were recorded from biceps brachii muscle with linear arrays of eight electrodes (silver bars 10mm apart, 5mm long, and 1mm diameter) in single differential configuration. Initial values and rates of change of Average Rectified Value (ARV), MeaN power Frequency (MNF) and muscle fiber Conduction Velocity (CV) were calculated to compare the effects of the two contraction modalities. No differences were found between "elastic session" and "weight session" PRE MVCs (31.9±8.8 and 29.9±8.3nm, respectively) and endurance times (28±6 and 26±7s, respectively). The same was observed for POST values. During the post-contraction isometric fatigue test, the only parameters influenced by the contraction modality were the initial CV and the rate of change in CV which were 12% and 37% greater (p<0.05) respectively after contractions performed with elastic resistance compared to free weights. These findings confirm others for which contractions done with the use of elastic band seem to require greater muscle activation; moreover, they highlight a sort of "muscle conditioning" after that specific contraction modality which requires the use of faster motor units. It is thus possible to consider the practical use of such elastic devices to increase the neuromuscular activation, for instance in specific rehabilitation settings where slow movements with minimal risk of injury are requested (post surgery rehabilitation, physical activity with elderly people or children).

PDE10A and PDE10A-dependent cAMP catabolism are dysregulated oppositely in striatum and nucleus accumbens after lesion of midbrain dopamine neurons in rat: a key step in parkinsonism physiopathology.

Loss of dopamine neurons in experimental parkinsonism results in altered cyclic nucleotide cAMP and cGMP levels throughout the basal ganglia. Our objective was to examine whether expression of phosphodiesterase 10A (PDE10A), an isozyme presenting a unique distribution in basal ganglia, is altered after unilateral injection of 6-hydroxydopamine in the medial forebrain bundle, eliminating all midbrain dopaminergic neurons, such that cyclic nucleotide catabolism and steady state could be affected. Our study demonstrates that PDE10A mRNA levels were decreased in striatal neurons 10 weeks after 6-hydroxydopamine midbrain lesion. Such changes occurred in the striatum ipsilateral to lesion and were paralleled by decreased PDE10A protein levels and activity in striatal neurons and in striato-pallidal and striato-nigral projections. However, PDE10A protein and activity were increased while PDE10A mRNA was unchanged in the nucleus accumbens ipsilateral to the 6-hydroxydopamine midbrain lesion. Accordingly, cAMP levels were down-regulated in the nucleus accumbens, and up-regulated in the striatum ipsilateral to the lesion, but they were not significantly changed in substantia nigra and globus pallidus. Unlike cAMP, cGMP levels were decreased in all dopamine-deafferented regions. The opposite variations of cAMP steady state in striatum and nucleus accumbens are concordant and likely dependent, at least in part, on the down-regulation of PDE10A expression and activity in the former and its up-regulation in the latter. On the other hand, the down-regulation of cGMP steady state in the striato-nigral and striato-pallidal complex is not consistent with and is likely independent from the concomitant down-regulation of PDE10A. Therefore, dopamine loss inversely regulates PDE10A gene expression in the striatum and PDE10A post-transcription in the nucleus accumbens, therein differentially modulating PDE10A-dependent cAMP catabolism.

Throwing velocity and kinematics in elite male water polo players.

AIM: Fifty-three members of the Italian Men Water Polo Team were filmed using two synchronized cameras, while they were shooting a goal. Considering the differences in body mass, height, training strategies and the technical-tactical features of the players, the aims of this study were to employ video-analysis techniques in order to investigate selected kinematic parameters in water polo throwing, and to provide comprehensive quantitative information on the throwing movement in relation to the different team player positions. METHODS: Video analysis was used to estimate the elbow angle at release, the shoulder angle at follow through, the back and head height at ball release, trunk rotation angle and ball velocity at release. RESULTS: Ball release velocities ranged from 21.0 to 29.8 m/s (average value 25.3±1.4 m/s), for field players. Goal keepers show the lowest team values (average 21.7±0.3 m/s). Similar to previous study results, ball release was typically reached just prior to the elbow approaching full extension (151.6±3.6°), and the follow through shoulder angle was 143±5.9°. CONCLUSION: No significant statistical difference was recorded between injured and non-injured athletes. No positive association was demonstrated between physical characteristics (body mass and height) and ball velocity.

Physiological profile of water polo players in different competitive levels.

AIM: The purpose of this study was to determine if there are different physiological characteristics in water polo players of three different competitive levels (national team, NT, junior national team, NJ, and amateur club, AC). METHODS: To better define the training levels of water polo players competing at different levels, we administered a shuttle swim test (SST, a specific test used by Italian coaches) and a classic speed-lactate test. The shuttle swim test is based on actions at maximum intensity followed by incomplete recoveries. To compare the athletes, we used their morphological characteristics, the speed during an incremental test associated with fixed blood lactate concentrations of 2 mmol*1-1 (Aerobic Threshold, AT) and 4 mmol*1-1 (Anaerobic Threshold, AnT), and the SST data (speed, heart rate and lactate concentration). RESULTS: The heart rate at the end of the SST was 164+/-12 beats*min-1 for NT, 166+/-10 beats*min-1 for NJ (no significant difference, P>0.05) and 179+/-9 beats*min-1 for AC (significantly different from NT and NJ, P<0.05). The AT and AnT speeds were significantly higher in NT than in AC and NJ (P<0.05). No significant differences were found in AT and AnT speeds between AC and NJ (P>0.05). The mean speed during the shuttle swim test was significantly higher in NT and NJ than in AC (P<0.05). Lactate values were similar in the NT, AC and NJ groups (P>0.05). The SST mean speed was significantly correlated with the AT (P<0.01) and AnT speeds (P<0.05) in three groups . In all groups no significant correlation was found between SST blood lactate and AT or AnT speeds (P>0.05). CONCLUSION: Some differences were found among the senior and junior professional and amateur water polo players in both SST performance and Aerobic and Anaerobic Thre-shold speeds. The shuttle swim test for water polo provides conditioning coaches and sport scientists with data on the sport-specific movement speed and the competition-specific fatigue resistance in each athlete.

Shuttle swim test for water polo players: validity and reliability.

AIM: The purpose of this study, carried out on elite water polo players, was to examine: 1) the relationship between the shuttle swim test (SST) and the performance during official water polo games, and 2) the SST reliability. METHODS: Sixteen male players of the Italian National Water Polo Team (age: 27.9 + or - 2.1 years, body mass: 88.5 + or - 10.3 kg, height: 186.6 + or - 6.9 cm) performed the SST, consisting of two sets of seven repetitions from 40 to 10 m (total of 120 m for each set) at a maximal intensity with 90 s of rest between sets. During the SST, average swimming speed, blood lactate concentration and heart rate were recorded. Direct validity of the SST was evaluated by comparing the average swimming speed with the total distance covered (TD) and the distance covered at high intensity swimming (above 1.8 m x s(-1), HIS) during three official water polo games. SST reliability was assessed by testing the same athletes one week apart. RESULTS: Average swimming speed during the SST was significantly correlated with TD (r=0.67, P<0.01) and HIS (r=0.74, P<0.004). The mean average speed during SST showed high reliability (TE=0.4%; CI 95%: 0.2% to 1.0% ). The T1 vs. T2 difference in mean average speed was not significant. CONCLUSIONS: Present findings demonstrate the validity and reliability of the SST for evaluation of the swimming fitness of water polo players.

Differences in myoelectric manifestations of fatigue in sprinters and long distance runners.

The aim of this study was to determine whether the rate of change of surface EMG variables during a constant force isometric fatiguing contraction (80% MVC, 30 s of duration) of vastus medialis obliquus (VMO) and vastus lateralis (VL) muscles is able to distinguish between nine sprinters and nine long distance runners. Signals were recorded with linear arrays of eight electrodes. Muscle fiber conduction velocity (CV), mean frequency (MNF) of EMG signal power spectrum and average rectified value (ARV) of the EMG signal were calculated both from the whole signal (global approach) and from motor unit action potentials (MUAP distribution approach) extracted from the signal. Results showed significant differences only in the MUAP distribution approach. For this approach, the rates of change of conduction velocity (CV) (both absolute and normalized with respect to the initial value) were found to be always greater in the sprinter (VMO: -0.012 +/- 0.011 m s(-2) and -0.25 +/- 0.21%/s; VL: -0.014 +/- 0.009 m s(-2) and -0.27 +/- 0.17%/s) than in the long distance runner group (VMO: -0.004 +/- 0.006 m s(-2) and -0.08 +/- 0.14%/s; VL: 0.003 +/- 0.012 m s(-2) and 0.08 +/- 0.26%/s) (VL: p = 0.016, VMO: p = 0.034). No differences were observed in the CV initial values and in rates of change of MNF, while MNF initial values recorded from the VMO were found to be greater (119.6 +/- 25.1 Hz) in the sprinter group than in the long distance runner group (99.2 +/- 12.1 Hz, p = 0.016). A correlation was found between initial values and rates of change of CV in the VMO (r = 0.61, p < 0.01, N = 18, Spearman correlation coefficient). The consistency of these findings with the expected fiber type composition between sprinters and long distance runners and the identification of a set of candidated variables for the assessment of muscle adaptation during training and/or rehabilitation programs represent the main results of the study.

Body cell mass measured by bioelectrical impedance spectroscopy in professional football (soccer) players.

AIM: The aim of this study was to measure body cell mass (BCM) in two football (soccer) teams and assess if there are differences in body composition among players of different field positions. METHODS: Two professional Italian (male) football teams, representing two different divisions (A and C), have been recruited. There were 14 players (4 forwards, 4 defenders, 6 midfielders) in A and 18 players (4 forwards, 4 defenders, 8 midfielders, 2 goalkeepers) in C. Fat free mass (FFM), fat mass (FM), percent body fat (%BF), and BCM have been assessed using bioelectrical impedance spectroscopy (BIS). RESULTS: There were no significant differences in age, body weight, height or body mass index between teams. Team A's BCM was approximately 4 kg greater than C (P=0.001). FFM was significantly greater in midfielders and defenders in A vs C (P=0.02). FFM was significantly lower in forwards compared to defenders within A (P=0.02). Within A, FM and %BF were significantly lower for defenders compared to forwards and midfielders (P=0.01), and BCM was significantly greater in forwards vs defenders (P=0.01), with no significant differences among other field positions. BCM was significantly greater in forwards vs midfielders and defenders within C (P=0.02), with no significant differences between midfielders and defenders. CONCLUSIONS: BCM, measured using BIS, represents an innovative, simple approach to assess body composition. The present study demonstrates that it is very important to analyze body composition in football players, not only with the aim to evaluate the variation of weight in a quantitative and qualitative way, but also with the purpose of selecting players for specific roles. Although these results must be considered not yet conclusive, they could be an important information for coaches, especially during the selection of young football players.

Manganese intoxication decreases the expression of manganoproteins in the rat basal ganglia: an immunohistochemical study.

Manganese (Mn) is a cofactor for some metalloprotein enzymes, including Mn-superoxide dismutase (Mn-SOD), a mitochondrial enzyme predominantly localized in neurons, and glutamine synthetase (GS), which is selectively expressed in astroglial cells. The detoxifying effects of GS and Mn-SOD in the brain, involve catabolizing glutamate and scavenging superoxide anions, respectively. Mn intoxication is characterized by impaired function of the basal ganglia. However, it is unclear whether regional central nervous system expression of manganoproteins is also affected. Here, we use immunocytochemistry in the adult rat brain, to examine whether Mn overload selectively affects the expression of GS, Mn-SOD, Cu/Zn-SOD, another component of the SOD family, and glial fibrillary acid protein (GFAP), a specific marker of astrocytes. After chronic Mn overload in drinking water for 13 weeks, we found that the number and immunostaining intensity of GS- and Mn-SOD-positive cells was significantly decreased in the striatum and globus pallidus, but not in the cerebral frontal cortex. In addition, we found that GS enzymatic activity was decreased in the strio-pallidal regions but not in the cerebral cortex of Mn-treated animals. In contrast, Cu/Zn-SOD- and GFAP-immunoreactivity was unchanged in both the cerebral cortex and basal ganglia of Mn-treated rats. Thus, we conclude that in response to chronic Mn overload, a down-regulation of some manganoproteins occurs in neurons and astrocytes of the striatum and globus pallidus, probably reflecting the vulnerability of these regions to Mn toxicity.

Multicompartment model to assess body composition in professional water polo players.

AIM: The aim of this study was to compare differences between skinfold thicknesses (SK), bioelectrical impedance analysis (BIA), a 2-compartment model (2C), and 2, 3-compartment models (3C) of percent body fat (%BF) assessment with a 4-compartment model (4C) in professional water polo athletes. METHODS: Ten male subjects, 18 to 29 years of age, participated in this study. Under water weighing, deuterium dilution, and dual-energy X-ray absorptiometry (DXA) were used to provide the required values for the models. The two, 3C models used were established by Withers et al. (3C-W) and by the DXA manufacturers (3C-DXA). 4C was also established by Withers et al. RESULTS: There were no significant differences between 2C, 3C-W, and 3C-DXA when compared with 4C (criterion model). There were no significant differences between 2C and 3C-W. %BF was significantly greater using 2C compared with 3C-DXA. %BF derived from SK and BIA were significantly greater than all other METHODS: 4C was best correlated with 3C-W (R2=0.998), followed by 2C (R2=0.806), 3C-DXA (R2=0.5071), SK (R2=0.2945), and BIA (R2=0.2377). CONCLUSION: We conclude that 2C and 3C-W assess %BF equally as well as 4C; however, SK and BIA significantly over-estimated %BF in water polo athletes.

A method for positioning electrodes during surface EMG recordings in lower limb muscles.

PURPOSE: The aim of this work is to provide information about the degree of inter-subject uniformity of location of innervation zone (IZ) in 13 superficial muscles of the lower limb. The availability of such information will allow researchers to standardize and optimize their electrode positioning procedure and to obtain accurate and repeatable estimates of surface electromyography (sEMG) signal amplitude, spectral variables and muscle fiber conduction velocity. METHODS: Surface EMG signals from gluteus maximus, gluteus medius, tensor faciae latae, biceps femoris, semitendinosus, vastus medialis obliquus, vastus lateralis, rectus femoris, tibialis anterior, peroneus longus, soleus, gastrocnemius medialis and lateralis muscles of ten healthy male subjects aged between 25 and 34 years (average = 29.2 years, S.D. = 2.5 years) were recorded to assess individual IZ location and signal quality. RESULTS: Tensor faciae latae, biceps femoris, semitendinosus, vastus lateralis, gastrocnemius medialis and lateralis showed a high level of both signal quality and IZ location uniformity. In contrast, rectus femoris, gluteus medius and peroneus longus were found to show poor results for both indexes. Gluteus maximus, vastus medialis obliquus and tibialis anterior were found to show high signal quality but low IZ location uniformity. Finally, soleus muscle was found to show low signal quality but high IZ location uniformity. CONCLUSIONS: This study identifies optimal electrode sites for muscles in the lower extremity by providing a standard landmarking technique for the localization of the IZ of each muscle so that surface EMG electrodes can be properly positioned between the IZ and a tendon.

Effect of different sports on body cell mass in highly trained athletes.

The objective of this study was to verify the impact of various sports on body cell mass (BCM). Ninety-eight male subjects, 17-33 years of age, participated in the study. The sample included athletes from three professional Italian football (soccer) teams, representing three different divisions (A, n=16; B, n=14; and C, n=18), judo athletes (J, n=10), and water polo athletes (W, n=14) who all competed at the national level. Twenty-six age-matched individuals served as the control group (CG). Fat-free mass (FFM), fat mass (FM), percent body fat (%BF), and BCM were assessed using bioimpedance spectroscopy (BIS). There were no significant differences in body weight and FFM among the groups. A and B were significantly taller than J and CG. B had a significantly lower body mass index (BMI; kg/m(2)) than CG, while C had a significantly lower BMI than J and CG. CG had a significantly greater FM and %BF than A, B, and C. C had a significantly lower BCM than Aand B. CG had a significantly lower BCM than A, B, J, and W. In conclusion, differences in BCM exist among athletes of different sports, and among athletes within the same sport who compete at different levels.

Body composition differences in adolescent female athletes and anorexic patients.

Osteopenia is a frequent complication affecting adolescent girls with anorexia nervosa (AN). Moreover, female athletes suffering from eating disorders can be affected by premature osteoporotic fractures. The aim of this study was to examine bone mineral content (BMC) and bone mineral density (BMD) in three groups of adolescent females. Anthropometric and body composition measurements were performed on 22 adolescent females (age+/-SD=15.6+/-1.4 years) divided into groups: athletes ( n=8), patients with AN ( n=8) and age-height matched control subjects ( n=6). Body weight and body mass index were significantly lower ( p<0.01) in athletes and AN patients compared with healthy controls. BMC and BMD were lower ( p<0.01) for AN patients and athletes compared with healthy controls; AN patients had the lowest BMC value. Athletes had higher lean body mass values compared with AN patients and healthy controls. These results suggest that the effects of eating disorders, specifically BMC loss, could be attenuated by physical activity.

Physical activity energy expenditure measured using a portable telemetric device in comparison with a mass spectrometer.

BACKGROUND: Several studies have evaluated the accuracy of portable metabolic gas analysis systems, which measure physical activity energy expenditure. Since the Cosmed K2 telemetric system, two K4 devices (RQ and b2) have been developed. OBJECTIVE: To compare measurements using the Cosmed K4 RQ with measurements by a traditional method (mass spectrometer) for a sample of healthy subjects performing physical exercise of various intensities. METHODS: Nine healthy male footballers (mean (SD) age 18.3 (2.2) years) performed an incremental exercise running test from 8 km/h to exhaustion, with an increase of 2 km/h for each level of the test protocol. The expired air was collected simultaneously using the Cosmed K4 RQ and Airspec QP9000 mass spectrometer. Oxygen consumption (VO2) and carbon dioxide production (VCO2) were measured at rest and at each exercise intensity. RESULTS: No significant differences were found between VO2 and VCO2 measured by the two instruments, at rest or during exercise. CONCLUSIONS: The application of the Cosmed K4 RQ system for VO2 and VCO2 measurements at rest and during both submaximal and maximal exercise may be of interest to sport physiologists, nutritionists, and doctors.

Effect of acute and chronic branched-chain amino acids on energy metabolism and muscle performance.

The aim of this study was to report the effects of acute and chronic branched-chain amino acids (BCAA) administration on energy metabolism and muscle performance. In the acute study which was double-blind, cross-over and placebo-controlled, 12 healthy male volunteers were administered orally on two consecutive days either BCAA (14.4 g/day) or isocaloric placebo; this was followed by measurement of oxygen consumption (VO2) and carbon dioxide production (VCO2) for 180 min by indirect calorimetry. In the chronic study, 10 healthy male volunteers were supplemented with BCAA (14.4 g/day) for 30 days. Before (T0) and after (T1) chronic BCAA administration, VO2, arm muscle area (AMA) and maximal voluntary contraction of forearm muscles (grip strength, GS) were evaluated. Acute study: Both meals increased mean respiratory quotient (RQ) from baseline: in the placebo group, this increase was short-term only (between 15 and 60 min), while this effect on RQ lasted for 120 min in the BCAA group. Moreover, between 30 and 90 min, mean RQ was significantly higher in the BCAA group than in the placebo group. Chronic study: GS increased significantly following chronic BCAA administration without significant changes in the AMA. At T0, VO2 increased significantly during the GS test, whereas at T1 no significant increase was observed. In conclusion, no excess thermogenesis could be detected as compared with placebo following acute BCAA administration, indirectly suggesting a relevant contribution of peripheral catabolic (bypassing liver) pathway to BCAA metabolism; furthermore, chronic BCAA supplementation improved the physical fitness of untrained healthy subjects, as demonstrated by the lack of 02 uptake increase during sustained hand grip test.

Bioelectrical impedance measures in different position and vs dual-energy X-ray absorptiometry (DXA).

BACKGROUND: Bioelectrical impedance analysis (BIA) is a safe, low-cost, non-invasive, rapid method for the assessment of body composition. It has therefore a great potential to be employed for epidemiological and clinical studies. However, many devices are available to estimate total body water (TBW), fat-free mass (FFM) and fat mass (FM) by bioelectrical impedance measurements. Moreover, bipedal devices allowing measurements in the only standing position are recently developed. They are easy and practical to use without operator, so a large diffusion can be forecasted in fields as sport and diet programs. Comparison of body composition estimation by a bipedal device with bioimpedance devices currently used, using dual-energy X-ray absorptiometry (DXA) as reference method. METHODS: The study was performed on 18 healthy women volunteers, age 32.0+/-10.7 years divided in two groups at different levels of body fatness. A Xitron 4000 impedance analyser, a BIA-101 RJL System, and the bipedal device Tanita were used for comparison. The measurements were performed in standing and supine position for Xitron and RJL devices. DXA measurements were performed with a total body scanner DPX, Lunar. RESULTS: FM and FFM were not statistically different when measured with Xitron and RJL in comparison with DXA, while these variables were significantly different between Tanita and DXA measurements. No significant difference were found between measurements in the supine and standing position with the Xitron and RJL system. CONCLUSIONS: Our results suggest that FM and FFM evaluated by bipedal device Tanita are significantly different from FM and FFM measured by DXA in both normal and obese population.

[Changes in body composition caused by intense physical training]. / Variazione della composizione corporea dovuta ad un intenso periodo di allenamento.

PURPOSE: To show the importance of the study of body composition in functional capacity evaluation of athletes who play professional football, during periods of very hard training (before the beginning of the championship), in order to appreciate every kind of adaptation to the training itself more precisely. MATERIALS AND METHODS: 18 semiprofessional football players, ages 18-32 yr., weight 75.2 +/- 8.1 kg, height 180.8 +/- 5.5 cm have been subjected to body composition evaluation, using Biolectrical Impedance Analysis (B.I.A) and antropometrics measurements, the day before the beginning of the trainings and at the end of them (just before the beginning of the championship). RESULTS: The athletes at end the training period (15 day) showed significant loss of weight (1.6 kg; p < 0.001). This reduction was attributed to a loss of the fat mass (2.8 kg; p < 0.001). Fat free mass increased 1.2 kg (p < 0.05); at the same time total body water increased too (1.0 l; p < 0.05) proving that, in spite of hard training, the athletes mateined a good hydratation. CONCLUSIONS: The results suggest that is very important to analyse body composition in the football players, since otherwise we couldn't attained the variation of weight in a quantitative and qualitative way.