Comparison of the finishing shot and ending zone of points in Grand Slam matches of women's doubles tennis: A cross-sectional study.

Despite the importance of doubles tennis, there is little research on this modality of the game, especially in women's tennis. The aim of this study was to analyse the finishing shot, the ending zone and shot by ending zone of women´s doubles matches during three Grand Slams (GS), and to observe the differences among surfaces. Twenty-one women's doubles matches from three GS, each played on a different surface were analysed. 56.4 ± 2.3% of the points were finished from the baseline and mid court zone (BMZ), 36.1 ± 2.3% from the net zone (NZ) and 7.5 ± 4.2% from the service zone (SZ). The shot with which the points ended primarily was the forehand volley (FV) (18.2 ± 3.5%), followed by the forehand (F) (17.4 ± 4.2%), the backhand (B) (15.8 ± 4.8%), the backhand volley (BV) (12.8 ± 3.6%), the forehand return (FRT) (11.7 ± 2.7%), the backhand return (BRT) (11.4 ± 2.6%), the service (S) (7.5 ± 4.2%) and the overhead (O) (5.2 ± 3.0%). The results showed a higher percentage of F played from the BMZ in Roland Garros (RG) than in Wimbledon (W) (p = 0.011). In addition, the results also showed a higher percentage in overall F in RG than in W (p = 0.023). The FRT percentage was higher in the Australian Open (AUS) compared to RG (p = 0.026), and the O shots played from the BMZ were higher in W than RG (p = 0.038). These results suggest that in professional women's doubles tennis the net game is a determinant factor, as well as the volley (V) and F shots. Playing aggressive and close to the net may have a positive effect on the result.

Observation system for the technical-tactical analysis of judo by the Rio 2016 Olympic champions.

An observational methodology system has been designed which allows the observation and analysis of the technical-tactical behaviour and interaction of judokas during competition. The observation instrument (JUTACTIC) is composed of 8 fixed criteria that provide information related to the competition and the competitors and 13 variable criteria that, throughout the intrasessional monitoring of each combat, allow the behaviour displayed by both judokas and their interaction to be recorded. From an observational sample consisting of matches from the Rio 2016 Olympic champions and the corresponding samples made using the LINCE PLUS software, evidence of validity, reliability, generalizability and applicability of the observation system is provided. The content validity of the observation instrument has been endorsed by a panel of experts (n = 11). Intra and inter-observer reliability has been guaranteed from the results obtained in the Fleiss Kappa and the Krippendorff Alpha. The generalizability analysis with the design structure [Category] [Participants] / [Matches] has confirmed that around seven matches are needed to accurately analyse the behaviour of the competitor under study. The practical application possibilities of the observation instrument has been shown with an example of the results obtained and the regular behaviour structures detected (T-patterns) using the THEME software.

Temporal demands of elite fencing.

There is no published study that analyses the temporal demands of fencing, in its six Olympic modalities in the same high-level competition. The only existing publications date back decades, with already obsolete regulations, or focus on a specific modality. The aim of this study is to carry out a chronometric analysis of elite fencing at the 2014 Fencing World Championships to determine the existence of differences between its weapons (épée, foil and sabre) and between genders. A total of 96 elite fencers (48 women) of 24 different nationalities were analysed in the final rounds (direct elimination). We undertook observational methodology based on an open and systematic process with ideographic, point and multi-dimensional design. We analysed the work time, rest time, total time, number of stops and work-to-rest ratio. The Lince software was used to record and analyse video data. The coding and recording process of the 83 fights analysed generated a matrix of 5900 records. The quality of the data was verified by checking the validity of the observation instrument and the intraobserver reliability. The mean work time (between Allez and Halte) was 17.9 ± 3.1 s for épée, 5.8 ± 2.5 s for foil and 1 .7 ± 0.4 s for sabre. The fight work-to-rest ratios recorded were 1:0.9, 1:2.6 and 1:9.2 for épée, foil and sabre respectively. The results showed significant differences (p < .05) in the work and rest times between the three fencing weapons. However, there were no differences between fencers of the same weapon according to gender.

Physiological demands and motion analysis of elite foil fencing.

The aim of this study was to determine the physiological demands and motion analysis of a simulated fencing competition. Eighteen fencers each completed 5 'poule' (5 touches) and 'direct elimination (DE)' (15 touches) fights. Expired gases were measured during 1 poule and DE fight. Heart rate (HR), ratings of perceived exertion (RPE) and movement data were recorded throughout all fights. Motion analysis was undertaken using the software LINCE PLUS. Differences between poule and DE fights were determined by either a paired t-test or a one-way repeated measures ANOVA. HR and RPE were significantly greater during DE compared to poule (170 ±10 vs 163 ±13 beats·min-1; P<0.05). A greater distance was covered during a DE fight compared to a poule fight (459.9 ± 117.7 m vs 162.6 ± 74.2 m; P<0.05). The average values of [Formula: see text] were 42.5 ±5.6 ml·kg-1·min-1 in men and 34.4 ±3.2 ml·kg-1·min-1 in women. Work-to-rest ratios reduced during the DE fights along with a lower average speed and increased max speed (11.7 ± 2.8 km∙h-1 vs 9.6 ± 1.6 km∙h-1; P<0.05). In conclusion, there is an increased physiological demand during a DE fight accompanied by a reduction in average speed and decreased work-to-rest ratio.

Comparing walking with knee-ankle-foot orthoses and a knee-powered exoskeleton after spinal cord injury: a randomized, crossover clinical trial.

Recovering the ability to stand and walk independently can have numerous health benefits for people with spinal cord injury (SCI). Wearable exoskeletons are being considered as a promising alternative to conventional knee-ankle-foot orthoses (KAFOs) for gait training and assisting functional mobility. However, comparisons between these two types of devices in terms of gait biomechanics and energetics have been limited. Through a randomized, crossover clinical trial, this study compared the use of a knee-powered lower limb exoskeleton (the ABLE Exoskeleton) against passive orthoses, which are the current standard of care for verticalization and gait ambulation outside the clinical setting in people with SCI. Ten patients with SCI completed a 10-session gait training program with each device followed by user satisfaction questionnaires. Walking with the ABLE Exoskeleton improved gait kinematics compared to the KAFOs, providing a more physiological gait pattern with less compensatory movements (38% reduction of circumduction, 25% increase of step length, 29% improvement in weight shifting). However, participants did not exhibit significantly better results in walking performance for the standard clinical tests (Timed Up and Go, 10-m Walk Test, and 6-min Walk Test), nor significant reductions in energy consumption. These results suggest that providing powered assistance only on the knee joints is not enough to significantly reduce the energy consumption required by people with SCI to walk compared to passive orthoses. Active assistance on the hip or ankle joints seems necessary to achieve this outcome.

Maximum aerobic speed, maximum oxygen consumption, and running spatiotemporal parameters during an incremental test among middle- and long-distance runners and endurance non-running athletes.

Background: Maximal aerobic speed (MAS) is a useful parameter to assess aerobic capacity and estimate training intensity in middle- and long-distance runners. However, whether middle- and long-distance runners reach different levels of MAS compared to other endurance athletes with similar V̇O2max has not been previously studied. Therefore, we aimed to compare V̇O2max, MAS and spatiotemporal parameters between sub-elite middle- and long-distance runners (n = 6) and endurance non-runners (n = 6). In addition, we aimed to compare the maximal blood lactate concentration [BLa] experienced by participants after conducting these tests. Methods: Telemetric portable respiratory gas analysis, contact and flight time, and stride length and rate were measured using a 5-m contact platform during an incremental test at a synthetic athletics track. V̇O2, heart rate, respiratory quotient values in any 15 s average period during the test were measured. [BLa] was analyzed after the test . Running spatiotemporal parameters were recorded at the last two steps of each 400 m lap. A coefficient of variation (%CV) was calculated for each spatiotemporal variable in each participant from 8 km h-1 onwards. Results: Whereas runners reported faster MAS (21.0 vs. 18.2 km h-1) than non-runners (p  =  0.0001, ES = 3.0), no differences were found for V̇O2max and maximum blood lactate concentration during the running tests (p > 0.05). While significant increases in flight time and stride length and frequency (p < 0.001, 0.52 ≤ η p 2 ≤ 0.8) were observed throughout the tests, decreases in contact time (p < 0.001, η p 2 = 0 . 9 ) were reported. Runners displayed a greater %CV (p = 0.015) in stride length than non-runners. We conclude that middle- and long-distance runners can achieve a faster MAS compared to non-running endurance athletes despite exhibiting a similar V̇O2max. This superior performance may be associated to a greater mechanical efficiency. Overall, runners displayed a greater ability to modify stride length to achieve fast speeds, which may be related to a more mechanically efficient pattern of spatiotemporal parameters than non-runners.

The Pick-and-Roll in Basketball From Deep Interviews of Elite Coaches: A Mixed Method Approach From Polar Coordinate Analysis.

Pick-and-roll is the most widespread cooperative action among high-level basketball teams and the most applied strategy by coaches to gain an advantage over the rival team. During pick-and-roll, opposing teams perform antagonistic actions based on goals that are expressed in offensive and defensive tactics. The aim of this study is to examine the approaches of high-level coaches on the offensive and defensive dynamics emerging in matches of a basketball elite team during an entire season of the Spanish Asociación de Clubes de Baloncesto (ACB) league. To this end, we used a mixed-methods approach based on systematic observation of verbatim transcripts of interviews conducted with six high-level coaches about the pick-and-roll dynamics that emerged in matches of the Unicaja Málaga team during an entire season of the ACB league. The observational design was nomothetic, punctual, and multidimensional. The choice of this methodology is justified since we developed an ad hoc indirect observation tool to evaluate the coaches' perspective on this dynamic. Once the intra-observer reliability of the instrument was confirmed, we performed a polar coordinate analysis to identify the significant relationships between the coaches' evaluations and the offensive and defensive pick-and-roll elements that supported such verbal behaviors. The results highlight the presence of various offensive and defensive aspects of pick-and-roll (n = 2224) emerging in the Unicaja team that were significantly associated with positive and negative evaluations of the coaches. The interview confirms that coach 1 and his staff were less confident in options that pick-and-roll offer, which is also reflected in the record of screens made and simulated, than coach 3. This study shows that the application of mixed methods, by analysis of the polar coordinate of the coding carried out on responses of a systematized interview, has proven to be an effective strategy in obtaining relevant information on the expert knowledge of the elite coaches on the influence of pick-and-roll on tactical actions in basketball.

LINCE PLUS software for systematic observational studies in sports and health.

This paper aims to offer a free software program, LINCE PLUS, suitable for systematic observational studies in sports and health, conducted in natural contexts such as training, education or psychology. Using one or several videos simultaneously, different parameters such as behaviors, decision-making or strategies can be analyzed. The software includes several functionalities for studies that researchers need to utilize throughout the observational study process. Collaborative work can be accomplished by using simultaneous videos and multiple observers. The results of all research conducted by LINCE PLUS are offered inside the application in real time, enabling common calculations or including specific analysis with R language without the need for any other external tool. Moreover, LINCE PLUS shows the results of each study with interactive charts or, if needed, it exports the data to specific data analysis software programs (e.g., SAS, Excel, Theme, GSEQ 5, Hoisan). We include examples of sports and health studies that have been conducted with LINCE PLUS to show the suitability of this software program.

Differences in Technical Development and Playing Space in Three UEFA Champions Leagues.

The analysis of football grows exponentially, with many researchers adopting it as an object of study. The thematic range that addresses it, as well as the different methodologies used, are of a very different nature-physical, psychological, technical, tactical-enriching every day the knowledge, and understanding of the game itself. The objective of this study has been to identify the differences between the different styles of play that lead to becoming the champion of the UEFA Champions League in the last 3 years of the pre-COVID stage, by analyzing the spatial performance developed, the association between the players that make up the different lines of the game system and the analysis of the various technical actions that are developed to carry out the offensive phase of each team. For this, the Observational Methodology and two types of analysis have been used: quantitative, by calculating X 2, and qualitative, by applying the Polar Coordinates technique. The results obtained show the relationship that is established between the different lines that make up the offensive systems of the champion teams of this competition, as well as the relationship of significance that is established between the use of space-width and depth-and the technical means used to achieve success, the goal.

Validity of Heart Rate-Based Models for Estimating Oxygen Uptake During Tennis Play.

Baiget, E, Iglesias, X, and Rodríguez, FA. Validity of heart rate-based models for estimating oxygen uptake during tennis play. J Strength Cond Res 34(11): 3208-3216, 2020-This study aimed to assess the validity of an on-court tennis test (specific endurance tennis test [SET-Test]) and 2 heart rate (HR)-based methods for estimating oxygen uptake (V[Combining Dot Above]O2) in competitive tennis players. Thirty-five male players performed a SET-Test to relate test duration (minutes) and V[Combining Dot Above]O2. Two weeks later, 16 players performed a simulated match play set where HR and V[Combining Dot Above]O2 (V[Combining Dot Above]O2-PLAY, criterion value) were measured and then compared with V[Combining Dot Above]O2 values predicted from the HR/V[Combining Dot Above]O2 linear regression equations derived from the SET-Test (pV[Combining Dot Above]O2-TEST) and from the one set match play (pV[Combining Dot Above]O2-PLAY). Test duration and V[Combining Dot Above]O2-TEST were strongly correlated (r = 0.821, p < 0.001, SEE = 5.6 ml·kg·min), indicating that SET-Test outcome is a somewhat good indicator of aerobic fitness in tennis players, likely to be useful for training purposes. pV[Combining Dot Above]O2-PLAY and V[Combining Dot Above]O2-PLAY (criterion value) were strongly correlated (r = 0.832, p < 0.001) and SEE was moderate (3.5 ml·kg·min = 11.5%). pV[Combining Dot Above]O2-TEST differed from the criterion (32.4 ± 10.7 vs. 30.8 ± 8.6 ml·kg·min, p < 0.001) and, although strongly correlated (r = 0.689, p < 0.001), an overestimation occurred (mean Δ = 1.6 ml·kg·min = 4.9%), yielding a high SEE (4.8 ml·kg·min = 15.6%). We conclude that (a) SET-Test performance is a valid and moderately accurate predictor of V[Combining Dot Above]O2; and (b) the individual HR-V[Combining Dot Above]O2 regression equation generated during tennis match play predicts V[Combining Dot Above]O2 with greater accuracy than the regression derived from the SET-Test.

Physiological demands of standing and wheelchair fencing in able-bodied fencers.

BACKGROUND: The purpose of this study was to determine the cardiorespiratory demands of standing and wheelchair (seated) fencing in a group of able-bodied fencers during simulated competitive bouts. METHODS: Participants were ten male able-bodied fencers of regional level with previous training experience in wheelchair fencing. After a standardized warm-up, participants performed two series of simulated competitive épée bouts (5 and 15 touches) in a random order, either while standing or while sitting in a wheelchair. Expired gas was analyzed for oxygen consumption (V̇O2) and respiratory exchange ratio (RER) and heart rate were continually monitored. Energy expenditure (EE) was subsequently calculated. RESULTS: V̇O2, HR and EE peak responses were greater during standing than seated fencing (P<0.05). Mean V̇O2 during all ST bouts (5- and 15-touch) was 43% greater than in wheelchair fencing (44.2±7.8 vs. 25.1±5.4 mL/kg/min). Mean HR during the standing 5- and 15-touch bouts was 91±20% and 84±7%, respectively, of that recorded during the seated bouts. HR, V̇O2 and EE data also indicated that the 15-touch bouts were more physiologically demanding than the 5-touch bouts (P<0.01). The HR-V̇O2 relationship was similar between both fencing modes. The duration of the 5- and 15-touch bouts were shorter for the seated than the standing bouts (P<0.01). CONCLUSIONS: The physiological demands of wheelchair fencing are lower than those for standing fencing. Furthermore, the physiology of 5 versus 15-touch bouts, similar to those undertaken in fencing competition, also differs.

Bioelectrical Impedance Vector Analysis (BIVA) and Body Mass Changes in an Ultra-Endurance Triathlon Event.

This study aimed to provide the first description of the whole-body bioimpedance vector of nine non-professional triathletes, and to assess body mass (BM) and vector variations evoked by an ultra-endurance triathlon event. Anthropometric and bioelectrical assessments were performed before (PRE), after (POST), and 48 hours following the race (POST48h). Bioimpedance vector analysis (BIVA) showed triathletes' vectors placed to the left of the major axis and mostly outside the 50% tolerance ellipse of the reference population. Vector migration in POST indicated dehydration, paralleled by a decrease in BM (p = 0.0001). Increased hydration status from POST to POST48h was suggested by a reversed vector migration and increased BM (p = 0.0001). Compared to PRE, POST48h values reflected fluid retention by changes in BIVA, while BM was still lower (p = 0.0001). Racing time was positively related to basal resistance -R/h- (r = 0.68; p = 0.04) and bioimpedance -Z/h- (r = 0.68; p = 0.045). Besides, basal R/h and Z/h were positively related to PRE-to-POST changes of R/h and Z/h (r = 0.80; p = 0.009). PRE-to-POST changes of R/h and Z/h were positively related to racing time (r = 0.80, p = 0.01) and internal workload (r = 0.80, p ≤ 0.02). Notwithstanding the lack of significant correlation between BM and bioelectrical parameters, the vector's behavior was explained from a multifactorial perspective (including BM variations) by using multiple regression analysis. On the other hand, BM changes were not related to racing time, internal workload or energy deficit (ranges: r = - 0.46 to 0.65; p = 0.06 to 0.98). In conclusion, these triathletes exhibit a specific bioelectrical distribution. Furthermore, vector migration was consistent with fluid loss induced by the event. Finally, vector analysis seems to provide additional information about hydration changes 48h after the event in comparison with BM alone.

Blood lactate accumulation during competitive freediving and synchronized swimming.

A number of competitive water sports are performed while breath-holding (apnea). Such performances put large demands on the anaerobic system, but the study of lactate accumulation in apneic sports is limited. We therefore aimed to determine and compare the net lactate accumulation (NLA) during competition events in six disciplines of competitive freediving (FD) and three disciplines of synchronized swimming (SSW). The FD disciplines were: static apnea (STA; n = 14); dynamic apnea (DYN; n = 19); dynamic apnea no fins (DNF; n = 16); constant weight (CWT; n = 12); constant weight no fins (CNF; n = 8); free immersion (FIM; n =10). The SSW disciplines were solo (n = 21), duet (n = 31) and team (n = 34). Capillary blood lactate concentration was measured before and three minutes after competition performances, and apneic duration and performance variables were recorded. In all nine disciplines NLA was observed. The highest mean (SD) NLA (mmol·L-1) was found in CNF at 6.3 (2.2), followed by CWT at 5.9 (2.3) and SSW solo at 5 (1.9). STA showed the lowest NLA 0.7 (0.7) mmol·L-1 compared to all other disciplines (P ⟨ 0.001). The NLA recorded shows that sports involving apnea involve high levels of anaerobic activity. The highest NLA was related to both work done by large muscle groups and long apneic periods, suggesting that NLA is influenced by both the type of work and apnea duration, with lower NLA in SSW due to shorter apneic episodes with intermittent breathing.

Oxidative stress in elite athletes training at moderate altitude and at sea level.

Using a controlled parallel group longitudinal trial design, we investigated the effects of different training interventions on the prooxidant/antioxidant status of elite athletes: living and training at moderate altitude for 3 (Hi-Hi3) and 4 weeks (Hi-Hi), and for 4 weeks too, living high and training high and low (Hi-HiLo) and living and training at sea level (Lo-Lo). From 61 swimmers, 54 completed the study. Nitrites, carbonyls, and lipid peroxidation (LPO) levels were assessed in plasma. Enzymatic antioxidants glutathione peroxidase (GPx) and glutathione reductase (GRd), and non-enzymatic antioxidants total glutathione (GST), reduced glutathione (GSH) and oxidized glutathione (GSSG) were analysed in the erythrocyte fraction. At the end of the intervention, nitrites levels were similar in all altitude groups but higher than in the Lo-Lo controls (P = .02). Hi-HiLo had greater GPx activity than Hi-Hi and Hi-Hi3 during most of the intervention (P ≤ .001). GRd activity was higher in Lo-Lo than in Hi-Hi at the end of the training camp (P ≤ .001). All groups showed increased levels of LPO, except Lo-Lo, and carbonyls at the end of the study (P ≤ .001). Training at altitude for 3 or 4 weeks drives oxidative stress leading to cellular damage mainly by worsening the antioxidant capacities. The GSSG/GSH ratio appears to be related to perceived exertion and fatigue. The stronger antioxidant defence showed by the Hi-HiLo group suggests an inverse relationship between redox alterations and performance. Further studies are required to investigate the role of oxidative stress in acclimatization, performance, and health.

Analysis of diachronic relationships in successful and unsuccessful behaviors by world fencing champions using three complementary techniques / Análisis de las relaciones diacrónicas en los comportamientos de éxito y fracaso de campeones del mundo de esgrima utilizando tres técnicas complementarias

The aim of this study was to investigate diachronic relationships in successful and unsuccessful behaviors by world fencing champions using three complementary techniques: T-pattern analysis, lag sequential analysis, and polar coordinate analysis. We employed a nomothetic, point, multidimensional observational design in which we analyzed 24 bouts fenced by six world fencing champions in 2014. The actions were recorded and coded using LINCE software. The results revealed a series of behaviors that were significantly associated with successful outcomes, and also identified actions that contributed to poorer performance. One key conclusion to be drawn from the study is that the use of these complementary techniques is perfectly feasible and holds great potential in the field of sport. Lag sequential analysis of occurrences at lag 0 (co-occurrences) and analysis of basic T-patterns provided tactical insights into the different fencing actions employed. This analysis is focused on the actions and reactions of each fencer and his rival during each exchange. Insights into combat strategy, by contrast, were provided by lag sequential analysis of occurrences at lags -1 to -5 and lags +1 to +5, analysis of T-pattern clusters, and polar coordinate analysis. In the last case, we observed how prospective and retrospective behaviors, reflected in the modification or extension of certain behaviors during each bout, improved the efficacy of actions performed throughout the competition (AU)

El objetivo de este estudio fue investigar las posibles relaciones diacrónicas en las conductas de éxito y fracaso en campeones del mundo de esgrima desde tres técnicas analíticas complementarias: detección de Tpatterns, análisis secuencial de retardos y análisis de coordenadas polares. Se utilizó un diseño observacional nomotético, puntual y multidimensional en el registro de 24 asaltos de los seis esgrimistas campeones del mundo de 2014. Se utilizó como instrumento de registro el software LINCE. Los resultados revelaron una serie de comportamientos que estaban estadísticamente asociados con la mejora del rendimiento deportivo y también se identificaron acciones que contribuyeron a empeorarlo. Una de las principales conclusiones que pueden extraerse de este estudio es que el uso de estas técnicas complementarias de análisis es perfectamente factible y tiene un gran potencial en el ámbito del deporte. El análisis secuencial en el retardo 0 (coocurrencias) y de las configuraciones básicas de los T-patterns proporcionan conocimientos tácticos sobre las diferentes acciones de esgrima empleadas. Este análisis se produce en el marco de la interacción entre las técnicas ejecutadas por cada tirador y su rival en cada acción del asalto. El análisis secuencial en los retardos -1 a -5 y +1 a +5, las agrupaciones de clusters de los T-patterns y el análisis de coordenadas polares contribuyen al análisis de la estrategia de combate. En este caso, se observaron cómo las conductas prospectivas y retrospectivas determinaron la consolidación o modificación de ciertos comportamientos durante cada asalto, con el fin de mejorar la eficacia de las acciones realizadas a lo largo de toda la competición (AU)

Bioelectrical impedance vector analysis (BIVA) for measuring the hydration status in young elite synchronized swimmers.

PURPOSE: The assessment of body hydration is a complex process, and no measurement is valid for all situations. Bioelectrical impedance vector analysis (BIVA) has emerged as a relatively novel technique for assessing hydration status in sports. We applied BIVA a) to determine hydration changes evoked by an intense synchronized swimming (SS) training session; b) to characterize the sample of young elite swimmers in relation with a nonathletic reference population; and c) to generate its 50%, 75% and 95% percentiles of the bioelectrical variables. METHODS: Forty-nine elite SS female swimmers of two age categories, comen (Co: 13.9 ± 0.9 years, n = 34) and junior (Jr: 16.3 ± 0.6 years, n = 15), performed a long, high intensity training session. Body mass (BM) and bioelectrical variables (R, resistance; Xc, reactance; PA, phase angle; and Z, impedance module) were assessed pre- and post-training. BIVA was used to characterize 1) the distribution pattern of the bioelectrical vector (BIA vector) for both age groups, and 2) pre- to post-training BIA vector migration. Bioelectrical variables were also correlated with BM change values. RESULTS: Most swimmers were mostly located outside the 75% and some beyond the 95% percentile of the bioelectrical tolerance ellipses of the general population. The BIA vector showed statistically significant differences in both Co (T2 = 134.7, p = 0.0001) and Jr (T2 = 126.2, p < 0.001). Both groups were also bioelectrically different (T2 = 17.6, p < 0.001). After the training session, a decrease in BM (p = 0.0001) and an increase in BIA variables (p = 0.01) was observed. BIVA also showed a significant pre-post vector migration both in Co (T2 = 82.1; p < 0.001) and Jr (T2 = 41.8; p < 0.001). No correlations were observed between BM changes and bioelectrical variables. CONCLUSIONS: BIVA showed specific bioelectrical characteristics in young elite SS athletes. Considering the decrease in BM and the migration of the BIA vector, we conclude that the homeostatic hydration status of these young elite female swimmers was affected by the execution of intense training sessions. From a methodological perspective, BIVA appears to be sensitive enough to detect subtle hydration changes, but further research is needed to ensure its validity and reliability. Moreover, these findings highlight the importance of ensuring adequate fluid intake during training in young SS athletes.

Validity of Postexercise Measurements to Estimate Peak VO2 in 200-m and 400-m Maximal Swims.

To assess the validity of postexercise measurements to estimate oxygen uptake (V˙O2) during swimming, we compared V˙O2 measured directly during an all-out 200-m swim with measurements estimated during 200-m and 400-m maximal tests using several methods, including a recent heart rate (HR)/V˙O2 modelling procedure. 25 elite swimmers performed a 200-m maximal swim where V˙O2 was measured using a swimming snorkel connected to a gas analyzer. The criterion variable was V˙O2 in the last 20 s of effort, which was compared with the following V˙O2peak estimates: 1) first 20-s average; 2) linear backward extrapolation (BE) of the first 20 and 30 s, 3×20-s, 4×20-s, and 3×20-s or 4×20-s averages; 3) semilogarithmic BE at the same intervals; and 4) predicted V˙O2peak using mathematical modelling of 0-20 s and 5-20 s during recovery. In 2 series of experiments, both of the HR/V˙O2 modelled values most accurately predicted the V˙O2peak (mean ∆=0.1-1.6%). The BE methods overestimated the criterion values by 4-14%, and the single 20-s measurement technique yielded an underestimation of 3.4%. Our results confirm that the HR/V˙O2 modelling technique, used over a maximal 200-m or 400-m swim, is a valid and accurate procedure for assessing cardiorespiratory and metabolic fitness in competitive swimmers.

Maximal Aerobic Frequency of Ball Hitting: A New Training Load Parameter in Tennis.

Baiget, E, Iglesias, X, and Rodríguez, FA. Maximal aerobic frequency of ball hitting: a new training load parameter in tennis. J Strength Cond Res 31(1): 106-114, 2017-This study aimed (a) to evaluate a new training load parameter in tennis based on the ball-hitting frequency (Ballf) at V[Combining Dot Above]O2max occurs (maximal aerobic frequency of ball hitting, MAF) and (b) to assess the accuracy of a specific endurance tennis test (SET-Test) for predicting MAF. Thirty-five male competitive tennis players performed the SET-Test and selected physiological and performance parameters at maximal workload (MAX), and last completed stage (LS) and MAF were compared. Performance parameters (Ballf, time, stage, and hits per test) at LS were higher than at MAF (20.2 ± 1.7 vs. 18.1 ± 1.5 shots·min, 6.6 ± 0.8 vs. 5.6 ± 0.8 stages, and 189 ± 33 vs. 147 ± 27 hits; p < 0.001), and highly correlated (r = 0.72-0.77; p < 0.001). The mean difference between Ballf and stage at MAF and LS were 2.1 ± 1.1 shots·min and 1.1 ± 0.6 stages, respectively. The main physiological parameters (heart rate, V[Combining Dot Above]O2, and V[Combining Dot Above]CO2 at LS) were higher than at MAF (191 ± 9 vs. 186 ± 8 beats·min, 55.5 ± 5.9 vs. 55.0 ± 6.0 ml·kg·min and 4,724 ± 880 vs. 4,253 ± 739 ml·min; p < 0.005), and were very strongly correlated (r = 0.93-0.99; p < 0.001). We conclude that MAF can be used as a practical performance parameter to prescribe tennis-specific training, and that the SET-Test is a valid method for assessing MAF. Gas exchange measurements not being available, as a rule of thumb, most players reach their MAF at ∼1 stage (95% confidence interval: 0.9-1.2) and ∼2 shots·min (95% confidence interval: 1.7-2.5) less than their completed LS. A model for specific on-court training protocols for optimizing aerobic fitness in competitive tennis player is proposed.

Estimating peak oxygen uptake based on postexercise measurements in swimming.

To assess the validity of postexercise measurements in estimating peak oxygen uptake (V̇O2peak) in swimming, we compared oxygen uptake (V̇O2) measurements during supramaximal exercise with various commonly adopted methods, including a recently developed heart rate - V̇O2 modelling procedure. Thirty-one elite swimmers performed a 200-m maximal swim where V̇O2 was measured breath-by-breath using a portable gas analyzer connected to a respiratory snorkel, 1 min before, during, and 3 min postexercise. V̇O2peak(-20-0) was the average of the last 20 s of effort. The following postexercise measures were compared: (i) first 20-s average (V̇O2peak(0-20)); (ii) linear backward extrapolation (BE) of the first 20 s (BE(20)), 30 s, and 3 × 20-, 4 × 20-, and 3 or 4 × 20-s averages; (iii) semilogarithmic BE at 20 s (LOG(20)) and at the other same time intervals as in linear BE; and (iv) predicted V̇O2peak using mathematical modelling (pV̇O2(0-20)]. Repeated-measures ANOVA and post-hoc Bonferroni tests compared V̇O2peak (criterion) and each estimated value. Pearson's coefficient of determination (r(2)) was used to assess correlation. Exercise V̇O2peak(-20-0) (mean ± SD 3531 ± 738 mL·min(-1)) was not different (p > 0.30) from pV̇O2(0-20) (3571 ± 735 mL·min(-1)), BE(20) (3617 ± 708 mL·min(-1)), or LOG(20) (3627 ± 746 mL·min(-1)). pV̇O2(0-20) was very strongly correlated with exercise V̇O2peak (r(2) = 0.962; p < 0.001), and showed a low standard error of the estimate (146 mL·min(-1), 4.1%) and the lowest mean difference (40 mL·min(-1); 1.1%). We confirm that the new modelling procedure based on postexercise V̇O2 and heart rate measurements is a valid and accurate procedure for estimating V̇O2peak in swimmers and avoids the estimation bias produced by other methods.