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.

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.

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.

Exercise modality effect on oxygen uptake off-transient kinetics at maximal oxygen uptake intensity.

NEW FINDINGS: What is the central question of this study? Do the mechanical differences between swimming, rowing, running and cycling have a potential effect on the oxygen uptake (V̇O2) off-kinetics after an exercise sustained until exhaustion at 100% of maximal oxygen uptake (V̇O2max) intensity? What is the main finding and its importance? The mechanical differences between exercise modes had a potential effect and contributed to distinct amplitude of the fast component (higher in running compared with cycling) and time constant (higher in swimming compared with rowing and cycling) in the V̇O2 off-kinetic patterns at 100% of V̇O2max intensity. This suggests that swimmers, unlike rowers and cyclists, would benefit more from a longer duration of training intervals after each set of exercise performed at V̇O2max intensity. The kinetics of oxygen uptake (V̇O2) during recovery (off-transient kinetics) for different exercise modes is largely unexplored, hampering the prescription of training and recovery to enhance performance. The purpose of this study was to compare the V̇O2 off-transient kinetics response between swimmers, rowers, runners and cyclists during their specific mode of exercise at 100% of maximal oxygen uptake (V̇O2max) intensity and to examine the on-off symmetry. Groups of swimmers, rowers, runners and cyclists (n = 8 per group) performed (i) an incremental exercise protocol to assess the velocity or power associated with V̇O2max (vV̇O2max or wV̇O2max, respectively) and (ii) a square-wave exercise transition from rest to vV̇O2max/vV̇O2maxwV̇O2maxwV̇O2max until volitional exhaustion. Pulmonary exchange parameters were measured using a telemetric portable gas analyser (K4b(2) ; Cosmed, Rome, Italy), and the on- and off-transient kinetics were analysed through a double-exponential approach. For all exercise modes, both transient periods were symmetrical in shape once they had both been adequately fitted by a double-exponential model. However, differences were found in the off-kinetic parameters between exercise modes; the amplitude of the fast component of the V̇O2 off-response was higher in running compared with cycling (48 ± 5 and 36 ± 7 ml kg(-1) min(-1) , respectively; P < 0.001), and the time constant of the same phase was higher in swimming compared with rowing and cycling (63 ± 5, 56 ± 5 and 55 ± 3 s, respectively; P < 0.001). Although both phases were well described by a double-exponential model, the differences between exercise modes had a potential effect and contributed to distinct V̇O2 off-transient kinetic patterns at 100% of V̇O2max intensity.

Heart rate deflection point relates to second ventilatory threshold in a tennis test.

The relationship between heart rate deflection point (HRDP) and the second ventilatory threshold (VT2) has been studied in continuous sports, but never in a tennis-specific test. The aim of the study was to assess the relationships between HRDP and the VT2, and between the maximal test performance and the maximal oxygen uptake ((Equation is included in full-text article.)) in an on-court specific endurance tennis test. Thirty-five high-level tennis players performed a progressive tennis-specific field test to exhaustion to determine HRDP, VT2, and (Equation is included in full-text article.). Ventilatory gas exchange parameters were continuously recorded by a portable telemetric breath-by-breath gas exchange measurement system. Heart rate deflection point was identified at the point at which the slope values of the linear portion of the time/heart rate (HR) relationship began to decline and was successfully determined in 91.4% of the players. High correlations (r = 0.79-0.96; p < 0.001) between physiological (HR and oxygen uptake [(Equation is included in full-text article.)]) and performance (Time, Stage, and Frequency of balls [Ballf]) variables corresponding to HRDP and VT2 were observed. Frequency of balls at the HRDP (BallfHRDP) was detected at 19.8 ± 1.7 shots per minute. Paired t-test showed no significant differences in HR (178.9 ± 8.5 vs. 177.9 ± 8.7 b·min for HRDP vs. HRVT2, respectively) at intensities corresponding to HRDP and VT2. Maximal test performance and (Equation is included in full-text article.)were moderately correlated (r = 0.56; p < 0.001). Heart rate deflection point obtained from this specific tennis test can be used to determine the VT2, and the BallfHRDP can be used as a practical performance variable to prescribe on-court specific aerobic training at or near VT2.

On-court endurance and performance testing in competitive male tennis players.

The aims of this study were (a) to establish a specific endurance test procedure for competitive tennis players, combining performance, physiological and technical parameters and (b) to determine the relationship between these parameters and their competitive levels. Thirty-eight competitive male tennis players (age, 18.2 ± 1.3 years; height, 180 ± 0.08 cm; body mass, 72.7 ± 8.6 kg; mean ± SD) performed a specific endurance field test. Performance (level achieved), physiological (heart rate, maximum oxygen uptake (VO2max), and ventilatory thresholds (VT1, VT2), and technical parameters (technical effectiveness [TE]) were assessed. Bivariate and multivariate models for predicting performance level were developed. Technical effectiveness was 63.1 ± 9.1%, with 3 identified phases throughout the test (adaptation, maximum effectiveness, and steady decline). Low to moderate correlations were found between performance (final stage), physiological (VT1, VT2) and TE, and competitive performance (r = 0.35-0.61; p = 0.038-0.000). Technical effectiveness explained 37% of variability in competitive performance (r = 0.61; p = 0.001). Using TE combined with VT2 or predictability increased explaining approximately 55% (p < 0.05) of the variance in competitive performance. The present study showed the usefulness of a field test including physiological and performance elements in high-caliber tennis players, and VT2 values combined with TE were good predictors of tennis performance.

Monitoring internal load parameters during competitive synchronized swimming duet routines in elite athletes.

The aim of the study is to compare the heart rate (HR) and rate of perceived exertion (RPE) responses as internal load indicators while performing duet routines during training and competition, both in the technical and free programs of synchronized swimming (SS). Participants were 10 SS Olympic medalists (age, 17.4 ± 3.0 years; height, 164.0 ± 6.1 cm; body mass, 52.0 ± 6.4 kg; training, 36.3 ± 6.2 h·wk; experience, 9.2 ± 2.6 years). They were monitored while performing the same technical duet or free duet, during a training session (T) and during an official competition (C). Heart rate was continuously monitored. Rate of perceived exertion was assessed using the Borg CR10 scale. Heart rate responses during T and C were almost identical: pre-exercise mean HR (b·min) was 130.5 ± 13.9 (T) and 133.6 ± 7.7 (C) and quickly increased yielding mean peak values of 184.8 ± 5.8 (T) and 184.8 ± 6.6 (C), with interspersed bradycardic events down to 86.6 ± 4 (T) and 86.3 ± 5 (C). Routines were perceived as "hard" to "extremely hard" by the swimmers in both conditions, and mean RPE scores (0-10+) were equally high during C (7.9 ± 1.2) and T (7.5 ± 1.2) (p = 0.223). Rate of perceived exertion inversely correlated with minimum (R = -0.545; p = 0.008) and mean HR (R = -0.452; p = 0.026) and positively correlated with HRrange (R = 0.520; p = 0.011). The internal load imposed by SS duets performed during training is virtually identical to that elicited in a real competitive situation. Therefore, practicing competitive routines is suitable for developing and maintaining the cardiovascular fitness that is needed for specific conditioning in elite synchronized swimmers, with the added value of favoring exercise automaticity, interindividual coordination, and artistic expression simultaneously.

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.

Plyometric jumping performances of male and female gymnasts from different heights.

The objective of this study was to investigate and compare the factors influencing plyometric jumping performance between well-trained gymnasts and a control group. Seventy-six gymnasts and 91 moderately active subjects volunteered to participate in this study. Drop jumps (DJ) were performed from 20-, 40-, 60-, 80-, and 100-cm heights. Flight time (FT) and contact time (CT) were recorded using contact mat. Flight time to contact time (FC) ratio and Bosco expression (BE) were calculated. Male gymnasts scored similar FT to their controls, whereas female gymnasts had significantly longer FT compared with their peers. The gymnasts obtained significantly shorter CT than their control groups, whereas their FC ratios were significantly higher and increased when the height of the drops was close to 60 cm. Moreover, gymnasts' BE was greater in comparison to their respective control groups independent of the drop height. The height of the drop that produced the best FC ratio and BE varied between the groups. The best performances were obtained between 40- and 60-cm drop height for both groups. Female control group showed a trend toward a continuing decline with the increase of the drop height. The best gymnasts (finalists at World Championships) obtained their best performance at 80-cm drop. Flight time is the less discriminating factor distinguishing gymnasts' DJ performances. Considering CT, FC, and BE results all together could better profile the gymnasts rather than taken separately. Bosco expression was shown to be more sensitive to the increase in FT; we suggest BE as the best criteria to assess the appropriate drop height for plyometric training purposes in gymnasts as it has been significantly correlated to FT.

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.

Reliability of squat and countermovement jump tests in children 6 to 8 years of age.

The aim of this study was to determine the reliability of the squat jump test (SJ) and countermovement jump test (CMJ), in fifty-six children (30 girls and 26 boys) with ages ranging from 6 to 8 years. Each subject performed two evaluation sessions (T1, T2) with seven days between tests. The results show that the CMJ test has a high intratrial reproducibility in T1 and T2 measured through intraclass correlation coefficient (ICC ≥ 0.95). The ICC for the SJ test had a high value (0.99) only in T1. The variability for both tests among children under 9 years of age is higher than those reported for adult subjects in other studies. The intersession reliability was questionable with a high methodical error (ME= 9.86-15.1%, for the SJ and CMJ, respectively) and a significant worsening of the results of CMJ in T2 (p < .05).

Effect of equated continuous and interval running programs on endurance performance and jump capacity.

We evaluated the effect of 2 different interval and continuous training programs on the maximal aerobic speed (MAS), time limit at MAS (T(lim)), and on the countermovement jump (CMJ). Twenty-two physically active men were randomly distributed in an interval training group (ITG), continuous training group (CTG), and control group. The CTG and ITG performed 2 different training programs (65-70 and 90-100% of the MAS for CTG and ITG, respectively) that consisted of 3 sessions per week during a period of 8 weeks with an identical external workload (% MAS × duration in minutes). The MAS, the T(lim) and the CMJ were recorded before and after the running training programs. The data analysis showed a significant and similar improvement (p < 0.01) of the MAS for both the ITG (5.8%) and CTG (8.3%). The T(lim) and CMJ did not change significantly for either group after the training period. Our results indicate that 8 weeks of continuous or interval running programs with externally equated load led to similar improvements in the MAS without changing T(lim) and CMJ performance in moderately trained nonrunners.

VO2 Off Transient Kinetics in Extreme Intensity Swimming.

UNLABELLED: Inconsistencies about dynamic asymmetry between the on- and off- transient responses in oxygen uptake are found in the literature. Therefore, the purpose of this study was to characterize the oxygen uptake off-transient kinetics during a maximal 200-m front crawl effort, as examining the degree to which the on/off regularity of the oxygen uptake kinetics response was preserved. Eight high level male swimmers performed a 200-m front crawl at maximal speed during which oxygen uptake was directly measured through breath-by-breath oxymetry (averaged every 5 s). This apparatus was connected to the swimmer by a low hydrodynamic resistance respiratory snorkel and valve system. RESULTS: The on- and off-transient phases were symmetrical in shape (mirror image) once they were adequately fitted by a single-exponential regression models, and no slow component for the oxygen uptake response was developed. Mean (± SD) peak oxygen uptake was 69.0 (± 6.3) mL·kg(-1)·min(-1), significantly correlated with time constant of the off- transient period (r = 0.76, p < 0.05) but not with any of the other oxygen off-transient kinetic parameters studied. A direct relationship between time constant of the off-transient period and mean swimming speed of the 200-m (r = 0.77, p < 0.05), and with the amplitude of the fast component of the effort period (r = 0.72, p < 0.05) were observed. The mean amplitude and time constant of the off-transient period values were significantly greater than the respective on- transient. In conclusion, although an asymmetry between the on- and off kinetic parameters was verified, both the 200-m effort and the respectively recovery period were better characterized by a single exponential regression model. Key pointsThe VO2 slow component was not observed in the recovery period of swimming extreme efforts;The on and off transient periods were better fitted by a single exponential function, and so, these effort and recovery periods of swimming extreme efforts are symmetrical;The rate of VO2 decline during the recovery period may be due to not only the magnitude of oxygen debt but also the VO2peak obtained during the effort period.

Physiological, biomechanical and anthropometrical predictors of sprint swimming performance in adolescent swimmers.

The purpose of this study was to analyze the relationships between 100-m front crawl swimming performance and relevant biomechanical, anthropometrical and physiological parameters in male adolescent swimmers. Twenty five male swimmers (mean ± SD: age 15. 2 ± 1.9 years; height 1.76 ± 0.09 m; body mass 63.3 ± 10.9 kg) performed an all-out 100-m front crawl swimming test in a 25-m pool. A respiratory snorkel and valve system with low hydrodynamic resistance was used to collect expired air. Oxygen uptake was measured breath-by-breath by a portable metabolic cart. Swimming velocity, stroke rate (SR), stroke length and stroke index (SI) were assessed during the test by time video analysis. Blood samples for lactate measurement were taken from the fingertip pre exercise and at the third and fifth minute of recovery to estimate net blood lactate accumulation (ΔLa). The energy cost of swimming was estimated from oxygen uptake and blood lactate energy equivalent values. Basic anthropometry included body height, body mass and arm span. Body composition parameters were measured using dual-energy X-ray absorptiometry (DXA). Results indicate that biomechanical factors (90.3%) explained most of 100-m front crawl swimming performance variability in these adolescent male swimmers, followed by anthropometrical (45.8%) and physiological (45.2%) parameters. SI was the best single predictor of performance, while arm span and ∆La were the best anthropometrical and physiological indicators, respectively. SI and SR alone explained 92.6% of the variance in competitive performance. These results confirm the importance of considering specific stroke technical parameters when predicting success in young swimmers. Key pointsThis study investigated the influence of different anthropometrical, physiological and biomechanical parameters on 100-m swimming performance in adolescent boys.Biomechanical factors contributed most to sprint swimming performance in these young male swimmers (90.3% of variability in performance), followed by anthropometrical (45.8%) and physiological (45.2%) parameters.Two selected variables (stroke index and stroke rate) explained 92.6% of the variance in competitive performance in these adolescent swimmers.

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.

The effect of intermittent hypobaric hypoxic exposure and sea level training on submaximal economy in well-trained swimmers and runners.

To evaluate the effect of intermittent hypobaric hypoxia combined with sea level training on exercise economy, 23 well-trained athletes (13 swimmers, 10 runners) were assigned to either hypobaric hypoxia (simulated altitude of 4,000-5,500 m) or normobaric normoxia (0-500 m) in a randomized, double-blind design. Both groups rested in a hypobaric chamber 3 h/day, 5 days/wk for 4 wk. Submaximal economy was measured twice before (Pre) and after (Post) the treatment period using sport-specific protocols. Economy was estimated both from the relationship between oxygen uptake (V(.-)o2) and speed, and from the absolute V(.-)o2 at each speed using sport-specific protocols. V(.-)o2 was measured during the last 60 s of each (3-4 min) stage using Douglas bags. Ventilation (V(.-)E), heart rate (HR), and capillary lactate concentration ([La(-)]) were measured during each stage. Velocity at maximal V(.-)o2 (velocity at V(.-)o2max) was used as a functional indicator of changes in economy. The average V(.-)o2 for a given speed of the Pre values was used for Post test comparison using a two-way, repeated-measures ANOVA. Typical error of measurement of V(.-)o2 was 4.7% (95% confidence limits 3.6-7.1), 3.6% (2.8-5.4), and 4.2% (3.2-6.9) for speeds 1, 2, and 3, respectively. There was no change in economy within or between groups (ANOVA interaction P = 0.28, P = 0.23, and P = 0.93 for speeds 1, 2, and 3). No differences in submaximal HR, [La-], Ve, or velocity at V(.-)o2(max) were found between groups. It is concluded that 4 wk of intermittent hypobaric hypoxia did not improve submaximal economy in this group of well-trained athletes.

Dynamics of the Metabolic Response During a Competitive 100-m Freestyle in Elite Male Swimmers.

PURPOSE: To compare the dynamics of maximal oxygen uptake ([Formula: see text]), blood lactate ([La]b), total energy expenditure (Etot), and contributions of the aerobic (Eaer), alactic anaerobic (Ean,al), and lactic anaerobic (Ean,lac) metabolic energy pathways over 4 consecutive 25-m laps (L0-25, L25-50, etc) of a 100-m maximal freestyle swim. METHODS: Elite swimmers comprising 26 juniors (age = 16 [1] y) and 23 seniors (age = 24 [5] y) performed 100 m at maximal speed and then 3 trials (25, 50, and 75 m) at the same pace as that of the 100 m. [La]b was collected, and [Formula: see text] was measured 20 s postexercise. RESULTS: The estimated energetic contributions for the 100-m trial are presented as mean (SD): Eaer, 51% (8%); Ean,al, 18% (2%); Ean,lac, 31% (9%). [Formula: see text] increased from L0-25 to L25-50 (mean = 3.5 L·min-1; 90% confidence interval [CI], 3.4-3.7 L·min-1 to mean = 4.2 L·min-1; 90% CI, 4.0-4.3 L·min-1) and then stabilized in the 2nd 50 m (mean = 4.1 L·min-1; 90% CI, 3.9-4.3 L·min-1 to mean = 4.2 L·min-1; 90% CI, 4.0-4.4 L·min-1). Etot (juniors, 138 [18] kJ; seniors, 168 [26] kJ), Ean,al (juniors, 27 [3] kJ; seniors, 30 [3] kJ), and Ean,lac (juniors, 38 [12] kJ; seniors, 62 [24] kJ) were 11-58% higher in seniors. Faster swimmers (n = 26) had higher [Formula: see text], 90% CI 4.4-4.8 L·min-1 [Formula: see text] L·min-1, 90% CI 3.6-4.2 L·min-1), and Eaer power was associated with fast performances (P < .001). CONCLUSION: Faster swimmers were characterized by higher [Formula: see text] and less time to reach the highest [Formula: see text] at ∼50 m of the 100-m swim. Anaerobic qualities become more important with age.

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.

Bioelectrical impedance vector analysis (BIVA) in sport and exercise: Systematic review and future perspectives.

BACKGROUND: Bioelectrical impedance vector analysis (BIVA) is a general concept that includes all methodologies used in the analysis of the bioelectrical vector, whereas the "classic" BIVA is a patented methodology included among these methods of analysis. Once this was clarified, the systematic review of the literature provides a deeper insight into the scope and range of application of BIVA in sport and exercise. OBJECTIVE: The main goal of this work was to systematically review the sources on the applications of BIVA in sport and exercise and to examine its usefulness and suitability as a technique for the evaluation of body composition, hydration status, and other physiological and clinical relevant characteristics, ultimately to trace future perspectives in this growing area, including a proposal for a research agenda. METHODS: Systematic literature searches in PubMed, SPORTDiscus and Scopus databases up to July, 2017 were conducted on any empirical investigations using phase-sensitive bioimpedance instruments to perform BIVA within exercise and sport contexts. The search included healthy sedentary individuals, physically active subjects and athletes. RESULT: Nineteen eligible papers were included and classified as sixteen original articles and three scientific conference communications. Three studies analysed short-term variations in the hydration status evoked by exercise/training through whole-body measurements, eleven assessed whole-body body composition changes induced by long-term exercise, four compared athletic groups or populations using the whole-body assessment, and two analysed bioelectrical patterns of athletic injuries or muscle damage through localised bioimpedance measurements. CONCLUSIONS: BIVA is a relatively new technique that has potential in sport and exercise, especially for the assessment of soft-tissue injury. On the other hand, the current tolerance ellipses of "classic" BIVA are not a valid method to identify dehydration in individual athletes and a new approach is needed. "Specific" BIVA, a method which proposes a correction of bioelectrical values for body geometry, emerges as the key to overcome "classic" BIVA limitations regarding the body composition assessment. Further research establishing standardised testing procedures and investigating the relationship between physiology and the bioelectrical signal in sport and exercise is needed.