MRP4-mediated cAMP efflux is essential for mouse spermatozoa capacitation.

Mammalian spermatozoa must undergo biochemical and structural changes to acquire the capacity for fertilization, in a process known as capacitation. Activation of PKA enzymes is essential for capacitation, and thus cAMP levels are tightly regulated during this process. Previously, we demonstrated that during capacitation, bovine spermatozoa extrude cAMP through multidrug resistance-associated protein 4 (MRP4, also known as ABCC4), which regulates intracellular levels of the nucleotide and provides cAMP to the extracellular space. Here, we report the presence of functional MRP4 in murine spermatozoa, since its pharmacological inhibition with MK571 decreased levels of extracellular cAMP. This also produced a sudden increase in PKA activity, with decreased tyrosine phosphorylation at the end of capacitation. Blockade of MRP4 inhibited induction of acrosome reaction, hyperactivation and in vitro fertilization. Moreover, MRP4 inhibition generated an increase in Ca2+ levels mediated by PKA, and depletion of Ca2+ salts from the medium prevented the loss of motility and phosphotyrosine inhibition produced by MK571. These results were supported using spermatozoa from CatSper Ca2+ channel knockout mice. Taken together, these results suggest that cAMP efflux via MRP4 plays an essential role in mouse sperm capacitation.This article has an associated First Person interview with the first author of the paper.

Is physical education an effective way to increase physical activity in children with lower cardiorespiratory fitness?

Several findings revealed the importance of accruing moderate and vigorous physical activity (MVPA) to improve health. Physical education (PE) may play an important role on promoting children's MVPA. However, it remains unknown whether PE might be effective when increasing physical activity (PA) levels in children with lower cardiorespiratory fitness (CRF). Therefore, the aim of this study was to assess children's PA during PE and during days with and without PE with a special focus on CRF status. One hundred and fifty Spanish children and adolescents from 3rd to 12th grade were recruited. PA levels were assessed with GT3X accelerometers. Peak oxygen uptake (VO2peak ) was estimated using a portable breath by breath Metamax 3B. Participants were classified as healthy aerobic fitness (HAF) and unhealthy aerobic fitness (UHAF) according to standardized cut-off point criteria. During PE, students with HAF accrued more MVPA than those with UHAF (8.7 vs 5.7 min/session; P ≤ 0.001). MVPA was higher on PE days than days without for both UHAF (50.0 vs 42.7 min/day; P ≤ 0.05) and HAF students (56.9 vs 49.4 min/day; P ≤ 0.05). Although less active during PE, students with lower CRF accumulated more MVPA and total PA on PE days than days without PE. An increase in PE days might be a smart policy to raise the recommended PA levels, regardless of CRF status.

Match activity and physiological load in wheelchair tennis players: a pilot study.

STUDY DESIGN: There is a lack of information about the physiological and psychological parameters in competition that shows a comprehensive profile of the demands of the game situation. OBJECTIVE: The aim of the present study was to examine the activity patterns and physiological-perceptual responses (heart rate (HR), blood lactate concentrations (LA) and the rate of perceived exertion (RPE), respectively, during singles wheelchair tennis (WT) matches. METHODS: A total of four WT players played three matches each. HR, LA and RPE were measured during each match. An activity pattern analysis was performed during all matches. Furthermore, LA and RPE were compared between service and return games. RESULTS: The results show a mean (s.d.) total match time of 69.04 (2.3) minutes, an effective playing time of 17.65% (0.03%), a work:rest (W:R) time ratio of 1:4.6 (0.48) and a rally length of 7.04 (4.44) seconds. Most of the points end in three or fewer shots. The mean (s.d.) physiological load during the matches were as follows: HR 124.25 (24.7) beats per minute, %HRmax 66.31% (4.5%), LA 1.41 (0.43) mmol l(-)(1) and RPE 12.45 (1.91). No significant differences were found in LA and RPE between service and return games (P>0.05). CONCLUSIONS: In this descriptive study, match activity and physiological load in WT are described. Match activities are similar to conventional tennis, although the physiological load is lower. Service and return situations show similar physiological and perceptual responses. These results might be used to develop specific interval training protocols for a male WT player.

Physical and physiological characteristics in male team handball players by playing position - Does age matter?

AIM: The purpose of this study was to examine the variation in physical and physiological characteristics according to playing position in adolescent and adult male team handball (TH) players. METHODS: Adolescent (N.=57, aged 14.9±1.4 yr) and adult (N.=39, 26.6±5.7 yr) players were examined for anthropometric characteristics, somatotype and body composition, and performed the physical working capacity test, a force-velocity test, the Wingate anaerobic test (WAnT), sit-and-reach test, handgrip strength test, squat jump (SJ), countermovement vertical jump without (CMJ) and with arm-swing, and a 30-s Bosco test. Eccentric utilization ratio (EUR) was calculated as the ratio CMJ to SJ. RESULTS: In adult players, there were significant differences between wings and the other positions with regard to anthropometric and body composition parameters (body mass, -17.9% to -13.2%; height, -5.3% to -4.3%; and fat-free mass, -13.7% to -9.9%) and anaerobic power assessed by WAnT (peak power, -20.5% to -15.2%; and mean power, -20% to -14.8%); however, these characteristics did not differ significantly in adolescents, in which the only statistically significant difference was found between goalkeepers and the other positions in EUR (+8.1%). CONCLUSION: Therefore, the differences in physical and physiological characteristics between playing positions are age-dependent. As adult players in this study were taken from players competing in the top Greek league, findings could serve as a base for talent identification and development for future studies. Moreover, knowledge about positional differences might enhance the ability to make tailored position-specific training programs among adult and adolescent players in the future.

Actigraph GT3X: validation and determination of physical activity intensity cut points.

The aims of this study were: to compare energy expenditure (EE) estimated from the existing GT3X accelerometer equations and EE measured with indirect calorimetry; to define new equations for EE estimation with the GT3X in youth, adults and older people; and to define GT3X vector magnitude (VM) cut points allowing to classify PA intensity in the aforementioned age-groups. The study comprised 31 youth, 31 adults and 35 older people. Participants wore the GT3X (setup: 1-s epoch) over their right hip during 6 conditions of 10-min duration each: resting, treadmill walking/running at 3, 5, 7, and 9 km · h⁻¹, and repeated sit-stands (30 times · min⁻¹). The GT3X proved to be a good tool to predict EE in youth and adults (able to discriminate between the aforementioned conditions), but not in the elderly. We defined the following equations: for all age-groups combined, EE (METs)=2.7406+0.00056 · VM activity counts (counts · min⁻¹)-0.008542 · age (years)-0.01380 · body mass (kg); for youth, METs=1.546618+0.000658 · VM activity counts (counts · min⁻¹); for adults, METs=2.8323+0.00054 · VM activity counts (counts · min⁻¹)-0.059123 · body mass (kg)+1.4410 · gender (women=1, men=2); and for the elderly, METs=2.5878+0.00047 · VM activity counts (counts · min⁻¹)-0.6453 · gender (women=1, men=2). Activity counts derived from the VM yielded a more accurate EE estimation than those derived from the Y-axis. The GT3X represents a step forward in triaxial technology estimating EE. However, age-specific equations must be used to ensure the correct use of this device.

Multiple sclerosis prevalence in Malaga, Southern Spain estimated by the capture-recapture method.

BACKGROUND: Although not definitively proven, there is commonly accepted to be a latitudinal gradient in the distribution of multiple sclerosis (MS), which is more frequent in temperate zones. The European Mediterranean countries are situated in a zone of median frequency, although ever increasing figures have been noted in the last decades. OBJECTIVE: The objective of this study was to assess the current prevalence rate of MS in the province of Malaga, Southern Spain. METHODS: The capture-recapture method (CRM) uses independent sources of data and permits the number of non-registered cases of a given disease to be estimated, and by doing so, to avoid ascertainment bias. RESULTS: Use of this method showed the estimated prevalence rate of MS in the province of Malaga, Southern Spain, to be 125/10(5) (95% confidence interval: 102/10(5)-169/10(5)), higher than the figures published previously. CONCLUSIONS: Although we recognize that these data need to be confirmed in further studies and in other areas of the country using a similar method, we believe this study is the first to find such high figure of prevalence, being very similar to the figures reported in recent years in other southern European countries.

Intermonitor variability of GT3X accelerometer.

The main purpose of this study was to assess the inter-monitor reliability of the tri-axial GT3X Actigraph accelerometer over a range of physical activities (PA). This device collects motion data on each of the vertical (Y), horizontal right-left (X), and horizontal front-back (Z) axes and also calculates the vector summed value √X(2)+Y(2)+Z(2) known as 'vector magnitude' (VM). 8 GT3X accelerometers were worn at the same time by the same participant. Accelerometers were placed back-to-front, all facing forward and in sets of 4 securely taped together, attached to a belt and allocating each block above either left or right hip at waist level. Inter-monitor reliability was assessed during 6 conditions: rest, walking (4 and 6 km·h(-1)), running (8 and 10 km·h(-1)) and repeated sit-to-stand (40 times·min(-1)). The intra-class correlation coefficients were high for X, Y and Z axes (i.e., all ≥ 0.925) and for VM (≥ 0.946). In conclusion, we found good inter-instrument reliability of the GT3X accelerometer across all planes, yet our results also suggest that the X and Z axes do not provide further benefits over the 'traditional' Y-axis to assess the movement in typical PA.

Effects of 7-weeks competitive training period on physiological and mental condition of top level judoists.

AIM: We examined hormonal and haematological parameters and the profile of mood states (POMS) in top level judoists undertaking a 7-week competitive training period in a real contest. METHODS: Participants were 10 top level judoists belonging to the Spanish National Team. Training load was calculated by multiplying the training session intensity by the duration of the training session. The judoists competed in two official events on weeks 3 and 6 of the study. RESULTS: Urinary catecholamines increased at the end of the competitive period. Serum cortisol increased during the weeks in which judoists competed, confirming the existence of and anticipatory cortisol response to exercise; although we failed to find serum testosterone increases. Because of leukocyte values did not change, except monocytes, we speculate that the intensity of training was not sufficiently high to evoke injury to muscle tissue. Anger, tension, and fatigue increased according with training load, suggesting that the training exercise led participants into a negative psychological state. CONCLUSION: Findings indicate that during competitive periods, judoists suffer hormonal and mood changes according to training load and competitive events. Results support the usefulness of monitoring biological and psychological markers during season in order to adjust training loads and periods of recovery.

Effects of different vibration exercises on bench press.

This study was undertaken to analyze the effects of different vibration recovery strategies via feet or hands on the number of repetitions performed and on mean velocity, peak velocity and blood lactate concentration during consecutive bench-press sets. 9 elite judo athletes performed 3 sets of bench press at 60% of one-repetition maximum (1RM), leading to failure and allowing a 180 s rest period between sets. During the rest period, 1 of the 3 following procedures was performed: 150 s rest plus 30 s push-up vibration exercise (Push-up), 150 s rest plus 30 s squat vibration exercise (Squat) or 180 s only rest (Passive). Statistical analysis revealed that the Squat condition resulted in a significant increase in the number of repetitions achieved, in comparison with all other rest strategies. However, kinematic parameters and blood lactate concentration were not affected by vibration. These data suggest that a vibration stimulus applied to the feet, between sets, can result in positive improvements in upper body resistance exercise performance. Although the mechanisms are not fully understood, this positive effect of vibration could be due to an increased motor cortex excitability and voluntary drive.

Physical activity and energy expenditure measurements using accelerometers in older adults.

The purpose of this review is to address methodological issues related to accelerometer-based assessments of physical activity (PA) in older individuals. Special interest is also put on recently updated technology. No definitive evidence exists currently to indicate which are the more valid and reliable accelerometer models for use with older people. When it comes to selecting an accelerometer, issues of affordability, product reliability, monitor size, technical support, and comparability with other studies may be equally as important as the relative validity and reliability of an instrument. The accelerometer should be attached as close as possible to the body's center of mass, and in the case of elders using walking aids, it should be placed on the same body side. Variability due to positioning can be reduced with careful training and supervision. Typically, the sampling period is between 3 and 7 days and it is not yet clear if variability exists between weekdays and weekend in the elderly. It is possible that aging effects on physical and cognitive health may limit the ability of an older adult to be compliant with an accelerometer protocol; in this line many methods have been suggested for increasing compliance to protocols for research studies. Accelerometers can provide reliable information on mobility and objective measurement of PA. These activity monitors have significant advantages when compared with other quantitative methods for measurement of energy expenditure. Accelerometers are currently used mainly in a research setting; however, with recent advances, incorporation into clinical and fitness practice is possible and increasing.

GHEP-ISFG collaborative exercise on mixture profiles (GHEP-MIX06). Reporting conclusions: Results and evaluation.

One of the main goals of the Spanish and Portuguese-Speaking Group of the International Society for Forensic Genetics (GHEP-ISFG) is to promote and contribute to the development and dissemination of scientific knowledge in the field of forensic genetics. Due to this fact, GHEP-ISFG holds different working commissions that are set up to develop activities in scientific aspects of general interest. One of them, the Mixture Commission of GHEP-ISFG, has organized annually, since 2009, a collaborative exercise on analysis and interpretation of autosomal short tandem repeat (STR) mixture profiles. Until now, six exercises have been organized. At the present edition (GHEP-MIX06), with 25 participant laboratories, the exercise main aim was to assess mixture profiles results by issuing a report, from the proposal of a complex mock case. One of the conclusions obtained from this exercise is the increasing tendency of participating laboratories to validate DNA mixture profiles analysis following international recommendations. However, the results have shown some differences among them regarding the edition and also the interpretation of mixture profiles. Besides, although the last revision of ISO/IEC 17025:2017 gives indications of how results should be reported, not all laboratories strictly follow their recommendations. Regarding the statistical aspect, all those laboratories that have performed statistical evaluation of the data have employed the likelihood ratio (LR) as a parameter to evaluate the statistical compatibility. However, LR values obtained show a wide range of variation. This fact could not be attributed to the software employed, since the vast majority of laboratories that performed LR calculation employed the same software (LRmixStudio). Thus, the final allelic composition of the edited mixture profile and the parameters employed in the software could explain this data dispersion. This highlights the need, for each laboratory, to define through internal validations its criteria for editing and interpreting mixtures, and to continuous train in software handling.

Recovery of ground ant (Hymenoptera: Formicidae) communities six years after a major environmental disaster.

The recovery of ant communities at the Guadiamar River bank (southwest Spain) was studied across 5 yr, after an environmental disaster caused by the spill of toxic sludge over the river caused by a mine accident. Three affected and three control sites were sampled from 2000 to 2004 using pitfall traps. The last year of study, a more exhaustive sampling was conducted at the affected area (eight sampling sites). Additionally, four adjacent study sites not affected by the toxic spill were also studied. Ants showed clear responses to the restoration of the area. Mean ant species richness in spillage affected sites showed a significant increase over the 5 yr. Moreover, multivariate analysis showed distinct changes of ant community composition of the affected area over the years that were not observed in control sites. Six years after the disaster, one half of the species recorded in control sites were also present in the affected area, with only one species exclusive to this area, Cardiocondyla mauritanica Forel (tramp species). However, not only habitat specialist species but also some generalist and conspicuous species within the river basin are not present along the affected area, including species of the genera Camponotus, Messor, Cataglyphis, and Aphaenogaster. This study shows an incipient recovery of ant communities 6 yr after a major environmental disturbance, highlighting the absence of any invasive ant species in the restored area.

[Interferon-beta response in multiple sclerosis associated with pre-treatment disability]. / Respuesta al interferon beta en la esclerosis multiple asociada con la discapacidad previa al tratamiento.

AIM: To study pre-treatment clinical features and influence of neutralising antibodies (NABs) in clinical response to interferon-beta (IFNB). PATIENTS AND METHODS: We analysed clinical characteristics and NABs to IFNB in 96 multiple sclerosis patients treated with IFNB. Clinical response was established by clinical criteria: = 1 relapse or an increase = 0.5 or 1 point in the Expanded Disability Status Scale (EDSS) score after one year of treatment compared with the year prior to IFNB therapy. RESULTS: Baseline clinical characteristics were similar for responders and non-responders, except for a significantly higher baseline mean EDSS score in non-responders. Time-to-first-relapse was longer and the number of patients relapse-free was higher for NAB-negative patients, but we were unable to show an association with the disability status, probably due to sample size. CONCLUSIONS: Response to IFNB was significantly associated with pre-treatment disability measured by the EDSS. The presence of NABs to IFNB presented a delayed negative effect for relapses.

The prevalence of multiple sclerosis in the Sanitary District of Vélez-Málaga, southern Spain.

Since little is known about the prevalence of multiple sclerosis (MS) in Spain, we undertook an epidemiologic study to ascertain the prevalence of MS in the Sanitary District of Vélez-Málaga, close to the city of Málaga, in southern Spain. The crude prevalence rate of MS in Vélez-Málaga was 53 per 100,000, twice as high as the prevalence previously reported in both the city and province of Málaga. The MS prevalence in the Sanitary District of Vélez-Málaga is similar to that in Sicily and in Cyprus.

Study of binding and neutralising antibodies to interferon-beta in two groups of relapsing-remitting multiple sclerosis patients.

Interferon (IFN)-beta is generally considered an effective treatment for multiple sclerosis (MS); however, some patients do not respond to this therapy, possibly due to the production of neutralising antibodies (NAB) which can prevent the biological effect of IFN-beta. We compared the two types of IFN-beta, the glycosylated IFN-beta1a and the non-glycosylated IFN-beta1b, as their chemical differences may entail differing immunogenic capacities. We studied 22 relapsing-remitting MS patients treated with IFN-beta1a and 31 treated with IFN-beta1b for 1 year, using the same assay and criteria, to compare the two types of IFN-beta in their ability to induce binding and neutralising antibodies and examined the correlation of the findings with the clinical data. Binding antibodies to IFN-beta1a and IFN-beta1b were determined by enzyme-linked immunosorbent assay. A bioassay was used to detect and quantify the NABs to IFN-beta, measuring the capacity of NABs to block the antiviral resistance induced by IFNs. Binding antibodies were found in 32 % of those treated with IFN-beta1a and in 52 % of those treated with IFN-beta1b; NABs were found in 14% and 24 %, respectively. Both groups showed a significant decrease in relapse rate during the first year of treatment. These results demonstrate that the IFN-beta1b molecule is more immunogenic than the IFN-beta1a molecule. This may be due to the non-glycosylated, chemical structure of the former, which can produce aggregates and enhance antibody production. No association was found between the presence of NABs and the clinical status of the patients.

DQB1*0602 allele shows a strong association with multiple sclerosis in patients in Malaga, Spain.

BACKGROUND: The human leukocyte antigen (HLA) class II DR2 haplotype (DRB1*1501, DQA1*0102, DQB1*0602) has been associated with multiple sclerosis (MS) in all ethnic groups and very strongly in Caucasians. AIM: To investigate the possible HLA class II (DRB1, DQA1 and DQB1) associations with MS in Malaga, southern Spain. METHODS: We analysed the HLA class II sub-regions DRB1, DQA1 and DQB1 by polymerase chain reaction (PCR) and sequence-specific oligonucleotide probe hybridization (PCR/SSO) for DRB1 and DQB1 and with sequence-specific primers (PCR/SSP) for DRB1 subtypes and DQA1. Possible HLA class II associations with clinical MS characteristics were investigated in 149 subjects with and 160 without MS. RESULTS: Associations were detected between MS and the HLA class II alleles DRB1*1501 (45.6 % vs. 21.3%, p=0.001), DQA1*0102 (44% vs. 29.4%, p=0.001) and DQB1*0602 (45% vs. 20.6%, p=0.001). The DR2 haplotype (DRB1*1501, DQA1*0102, DQB1*0602) was associated with MS (43.6 % vs. 20%, p=0.002). DQB1*0602 was the only allele that maintained an association with MS in a logistic regression model. No HLA class II alleles or genotypes were significantly associated with any clinical characteristics of MS. CONCLUSIONS: Our results confirm the positive association of the DR2 haplotype with MS, particularly the allele DQB1*0602, in the population studied. DR4 was not associated with the disease in Malaga. HLA class II alleles or haplotypes were not associated with clinical or demographic characteristics, or clinical form or severity of MS.

Clinical presentation of children with pulmonary tuberculosis: 25 years of experience in Lima, Peru.

OBJECTIVE: To describe clinical presentation across age groups in 2855 children with pulmonary tuberculosis (TB) attending the Children's Hospital, Lima, Peru, to improve the diagnosis, treatment and care of childhood TB. DESIGN: Children aged 0-14 years admitted between 1 January 1973 and 31 December 1997 with active pulmonary TB were enrolled. Demographic information, history, physical examination data, laboratory and microbiological results, chest radiograph data, disease classification, treatment and adverse effect data, and outcome at the time of discharge were recorded by pulmonologists using detailed chart abstractions. RESULTS: Of the 2855 enrollees, 47% were malnourished and 56% had a household contact. Older children presented with classic TB symptoms, while weight loss and anorexia were rare in children aged <5 years. Microbiological or pathologic confirmation was obtained in 71% of children aged 10-14 years compared with 34% of children aged <2 years; however, severe extra-pulmonary TB was most common among children aged <2 years (41%). CONCLUSION: Classic TB symptoms should be considered when making a diagnosis; however, systematic symptoms among young children are also important. In high-burden settings, clinicians should have a low threshold to diagnose and treat children for TB across all ages, even in the context of a negative tuberculin skin test result and lack of micro-pathological confirmation.

GHEP-ISFG collaborative exercise on mixture profiles of autosomal STRs (GHEP-MIX01, GHEP-MIX02 and GHEP-MIX03): results and evaluation.

One of the main objectives of the Spanish and Portuguese-Speaking Group of the International Society for Forensic Genetics (GHEP-ISFG) is to promote and contribute to the development and dissemination of scientific knowledge in the area of forensic genetics. Due to this fact, GHEP-ISFG holds different working commissions that are set up to develop activities in scientific aspects of general interest. One of them, the Mixture Commission of GHEP-ISFG, has organized annually, since 2009, a collaborative exercise on analysis and interpretation of autosomal short tandem repeat (STR) mixture profiles. Until now, three exercises have been organized (GHEP-MIX01, GHEP-MIX02 and GHEP-MIX03), with 32, 24 and 17 participant laboratories respectively. The exercise aims to give a general vision by addressing, through the proposal of mock cases, aspects related to the edition of mixture profiles and the statistical treatment. The main conclusions obtained from these exercises may be summarized as follows. Firstly, the data show an increased tendency of the laboratories toward validation of DNA mixture profiles analysis following international recommendations (ISO/IEC 17025:2005). Secondly, the majority of discrepancies are mainly encountered in stutters positions (53.4%, 96.0% and 74.9%, respectively for the three editions). On the other hand, the results submitted reveal the importance of performing duplicate analysis by using different kits in order to reduce errors as much as possible. Regarding the statistical aspect (GHEP-MIX02 and 03), all participants employed the likelihood ratio (LR) parameter to evaluate the statistical compatibility and the formulas employed were quite similar. When the hypotheses to evaluate the LR value were locked by the coordinators (GHEP-MIX02) the results revealed a minor number of discrepancies that were mainly due to clerical reasons. However, the GHEP-MIX03 exercise allowed the participants to freely come up with their own hypotheses to calculate the LR value. In this situation the laboratories reported several options to explain the mock cases proposed and therefore significant differences between the final LR values were obtained. Complete information concerning the background of the criminal case is a critical aspect in order to select the adequate hypotheses to calculate the LR value. Although this should be a task for the judicial court to decide, it is important for the expert to account for the different possibilities and scenarios, and also offer this expertise to the judge. In addition, continuing education in the analysis and interpretation of mixture DNA profiles may also be a priority for the vast majority of forensic laboratories.

Comparative study of the electrochemical behavior and analytical applications of (bio)sensing platforms based on the use of multi-walled carbon nanotubes dispersed in different polymers.

This review present a critical comparison of the electrochemical behavior and analytical performance of glassy carbon electrodes (GCE) modified with carbon nanotubes (CNTs) dispersed in different polymers: polyethylenimine (PEI), PEI functionalized with dopamine (PEI-Do), polyhistidine (Polyhis), polylysine (Polylys), glucose oxidase (GOx) and double stranded calf-thymus DNA (dsDNA). The comparison is focused on the analysis of the influence of the sonication time, solvent, polymer/CNT ratio, and nature of the polymer on the efficiency of the dispersions and on the electrochemical behavior of the resulting modified electrodes. The results allow to conclude that an adequate selection of the polymers makes possible not only an efficient dispersion of CNTs but also, and even more important, the building of successful analytical platforms for the detection of different bioanalytes like NADH, glucose, DNA and dopamine.

Step test and physical working capacity in female volleyball players: the paradox of better performance in the older athletes / Test de Step y capacidad de trabajo en jugadoras de voleibol: la paradoja de un mejor rendimiento en las jugadoras mayors / Teste do degrau e capacidade de trabalho em jogadores de voleibol: o paradoxo de um desempenho melhor em jogadores mais velhos

The aim of the present study was to compare two popular submaximal tests of aerobic capacity, the YMCA step test and the physical working capacity at heart rate (HR) 170 bpm test (P170), in competitive female volleyball players. The participants (n = 152, age 12.78-41.67 yrs) were examined for anthropometric characteristics and performed the YMCA step test. Heart rate (HR) was recorded at the end of the test (Stepend) and at the end of the first minute of recovery (Steprec). P170 test was expressed in both absolute (P170,abs, W) and relative values (P170,rel, W.kg-1). In addition, a sub-group (n = 14) was tested again one year later. The YMCA step test correlated largely (Steprec) and very largely (Stepend) with P170,rel (r = -0.58 and r = -0.76, p < 0.001, respectively), and P170,abs (r = -0.54 and r = -0.68, p < 0.001, respectively). No correlation was observed among percentage changes in the tests of aerobic capacity over a year (p > 0.05). Age correlated low-to-moderately with all indices of aerobic capacity (0.23 ≤ │r│ ≤ 0.45, p < 0.05), i.e. the older the age, the better the aerobic capacity. Based on the findings of the present study, it was concluded that the YMCA step test (especially the Stepend index) and P170 might be used interchangeably by coaches and trainers to monitor aerobic capacity of female volleyball players. The paradoxically increase of aerobic capacity with age should be attributed to the assessment methods which were based on HR and to the decrease of maximal HR with age. Thus, these tests should be used only within a short range of age (AU)

El objetivo del presente estudio fue comparar dos pruebas submáximas de capacidad aeróbica, el YMCA step test y la prueba de capacidad de trabajo físico a 170 ppm (P170) de frecuencia cardíaca (FC), en jugadoras de voleibol femenino. Se analizaron en 152 participantes variables antropométricas, el rendimiento, la frecuencia cardiaca final (Stepend) y la frecuencia cardiaca en el primer minuto de recuperación (Steprec) en la prueba YMCA step test, la P170 fue analizada expresando los resultados en valores absolutos (P170,abs, W) y relativos (P170,rel, W.kg-1). Además, un subgrupo (n=14) fue analizado otra vez después de un año. Los resultados mostraron como el YMCA step test correlacionó altamente (Steprec) y muy altamente (Stepend) con la P170 rel (r = -0.58 and r = -0.76, p < 0.001, respectively), y con la P170,abs (r = -0.54 and r = -0.68, p < 0.001, respectively). No se encontraron correlaciones entre los porcentajes de cambio en los test de capacidad aeróbica después de un año (p>0.05). La edad presentó una correlación baja a moderada con todos los índices de capacidad aeróbica (0.23 ≤ │r│ ≤ 0.45, p < 0.05), viendo como las mayores edades tenían una mejor capacidad aeróbica. Basándonos en estos resultados podemos concluir que la prueba YMCA step test (especialmente el parámetro Stepend) y la P170 podrian ser utilizadas indistintamente por entrenadores y preparadores físicos para monitorizar la capacidad aeróbica de jugadoras de voleibol. El paradójico incremento de la capacidad aeróbica con la edad puede ser atribuido a los métodos de evaluación utilizados que están basados en la FC y al descenso de la FC máxima con la edad. Por lo tanto, estos test deberían ser utilizados solo con edades inferiores (AU)

O objetivo deste estudo foi comparar dois testes de capacidade aeróbia submáximas, o teste do degrau YMCA ea capacidade de trabalho físico a 170 ppm (P170) da frequência cardíaca (FC) em jogadores de voleibol das mulheres. Foram analisados 152 variáveis antropométricas envolvidos, o desempenho, a freqüência cardíaca final (Stepend) e freqüência cardíaca no primeiro minuto da recuperação (Steprec) no teste de etapa de teste YMCA, o P170 foi analisado expressando os resultados em valores absolutos (P170 , ABS, W) e relativo (P170, rel, W.kg-1). Além disso, um subgrupo (n = 14) foi analisada outra vez depois de um ano. Os resultados mostraram que o passo de ensaio ACM altamente correlacionados (Steprec) e muito alta (Stepend) com P170 rel (r = -0,58 e r = -0,76, p 0,05). Idade apresentou uma baixa a moderada correlação com todos os índices de capacidade aeróbica (│r│ ≤ 0,23 ≤ 0,45, p< 0,05), observando as idades mais velhas tinham melhor capacidade aeróbica. Com base nestes resultados, podemos concluir que o teste de teste YMCA etapa (especialmente parâmetro Stepend) e P170 pode ser usado indiscriminadamente pelos treinadores e preparadores físicos para monitorar a capacidade aeróbia de atletas de voleibol. O aumento paradoxal na capacidade aeróbica com a idade pode ser atribuído aos métodos de avaliação utilizados, que são baseados no FC eo declínio da frequência cardíaca máxima com a idade. Portanto, estes testes devem ser usados apenas com idades mais jovens (AU)