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This study aims to integrate an open-source software capable of estimating hydrodynamic forces solely from kinematic data with a full-body biomechanical model of the human body to enable inverse dynamic analyses of swimmers. To demonstrate the methodology, intersegmental forces and joint torques of the lower limbs were computed for a six-beat front crawl swimming motion, acquired at LABIOMEP-UP. The hydrodynamic forces obtained compare well with existing numerical literature. The intersegmental forces and joint torques obtained increase from distal to proximal joints. Overall, the results are consistent with the limited literature on swimming biomechanics, which provides confidence in the presented methodology. [ABSTRACT FROM AUTHOR]

Our purpose was to verify if the use of the new AquaTrainer® respiratory snorkel lead to an increase of front crawl hydrodynamic drag and whether the constraint of using an adapted turning technique influences its corresponding turning time. 12 swimmers performed 2 (without and with snorkel) 12x25 front crawl repetitions from low to maximal velocity on the measuring active drag system. Complementarily, 3 swimming turns were compared: open turn with snorkel, tumble turn and open turn without snorkel. Drag values were similar without vs. with snorkel at 0.9,1.1,1.3,1.5 and 1.7 m.s-1 velocities: 15.84± 5.32 vs. 16.18±4.81, 25.60±6.69 vs. 26.03±6.17, 38.37±8.04 vs. 38.88±7.56, 54.64±10.06 vs. 55.08±9.55, 74.77±14.09 vs. 74.92 ±13.14N, (respectively, p≥0.05), and high agreement between conditions was observed (p<0.01). Front crawl swimming with snorkel using the open turn implied an increase in turning time of 14.2 and 5.1% than the tumble turn and open turn without the apparatus (p<0.01). AquaTrainer® snorkel does not lead to an increase in active drag during front crawl performed at a large range of velocities and, consequently, the metabolic energy necessary to overcome total drag will not be affected. However, turning with it requires an additional time that should be taken into account in scientific research and training conditions. [ABSTRACT FROM AUTHOR]

Purpose: Our purpose was to characterize the oxygen uptake ([Formula: see text]) kinetics, assess the energy systems contributions and determine the energy cost when swimming front crawl at extreme intensity. Complementarily, we compared swimming full body with upper body only.Methods: Seventeen swimmers performed a 100 m maximal front crawl in two conditions: once swimming with full body and other using only the upper propulsive segments. The [Formula: see text] was continuously measured using a telemetric portable gas analyser (connected to a respiratory snorkel), and the capillary blood samples for lactate concentration analysis were collected.Results: A sudden increase in [Formula: see text] in the beginning of exercise, which continuously rose until the end of the bout (time: 63.82 ± 3.38 s; [Formula: see text]: 56.07 ± 5.19 ml min(-1) kg(-1); [Formula: see text] amplitude: 41.88 ± 4.74 ml min(-1) kg(-1); time constant: 12.73 ± 3.09 s), was observed. Aerobic, anaerobic lactic and alactic pathways were estimated and accounted for 43.4, 33.1 and 23.5 % of energy contribution and 1.16 ± 0.10 kJ m(-1) was the energy cost. Complementarily, the absence of lower limbs lead to a longer time to cover 100 m (71.96 ± 5.13 s), slower [Formula: see text] kinetics, lower aerobic and anaerobic (lactic and alactic) energy production and lower energy cost.Conclusion: Despite the short duration of the event, the aerobic energy contribution covers about 50 % of total metabolic energy liberation, highlighting that both aerobic and anaerobic energy processes should be developed to improve the 100 m swimming performance. Lower limbs action provided an important contribution in the energy availability in working muscles being advised its full use in this short duration and very high-intensity event. [ABSTRACT FROM AUTHOR]

Cardiorespiratory response in swimming has been used to better understand aerobic performance, especially by assessing oxygen uptake (VO2 ). The current study aimed to compare different VO2 time-averaging intervals throughout low to severe swimming intensities, hypothesizing that VO2 values are similar for different time averages at low to moderate and heavy swimming intensities, but not for the severe domain. 20 male trained swimmers completed an incremental protocol of 7 × 200 m until exhaustion (0.05 m/s increments and 30 s intervals). VO2 was measured by a portable gas analyser connected to a snorkel system. 6 time average intervals (breath-by-breath, 5, 10, 15, 20 and 30 s) were compared for all the protocol steps. Breath-by-breath and 5 s average exhibited higher VO2 values than averages ≥ 10 s for all swimming intensities ( P ≤ 0.02; partial η2 ≤ 0.28). VO2 values did not differ between 10, 15, 20 and 30 s averages throughout the incremental protocol ( P > 0.05; partial η2 ≤ 0.05). Furthermore, 10 and 15 s averages showed the lowest VO2 mean difference (0.19 mL · kg−1 · min−1 ). For the 6 time average intervals analysed, 10 and 15 s averages were those that showed the lowest changes on VO2 values. We recommended the use of 10 and 15 s time averaging intervals to determine relevant respiratory gas exchange parameters along a large spectrum of swimming intensities. [ABSTRACT FROM AUTHOR]

The Cosmed AquaTrainer ® snorkel, in connection with the K4b 2 analyzer, is the most recent instrument used for real time gas analysis during swimming. This study aimed to test if a new AquaTrainer ® snorkel with 2 (SV2) or 4 (SV4) valves is comparable to a standard face mask (Mask) being valid for real time gas analysis under controlled laboratory and swimming pool conditions. 9 swimmers performed 2 swimming and 3 cycling tests at 3 diff erent workloads on separate days. Tests were performed in random order, at constant exercise load with direct turbine temperature measurements, breathing with Mask, SV4 and SV2 while cycling, and with SV2 and SV4 while swimming. A high agreement was obtained using Passing - Bablok regression analysis in oxygen consumption, carbon dioxide production, tidal volumes, pulmonary ventilation, expiratory fraction of oxygen and carbon dioxide, and heart rate comparing diff erent conditions in swimming and cycling. Proportional and fi xed diff erences were always rejected (95 % CI always contained the value 1 for the slope and the 0 for the intercept). In conclusion, the new SV2 AquaTrainer ® snorkel, can be considered a valid device for gas analysis, being comparable to the Mask and the SV4 in cycling, and to the SV4 in swimming. [ABSTRACT FROM AUTHOR]

The purpose of this study was to analyse eventual kinematic and electromyographic changes during a maximal 200 m front crawl at race pace. 10 male international level swimmers performed a 200 m maximal front crawl test. Images were recorded by 2 above and 4 under water cameras, and electromyographic signals (EMG) of 7 upper and lower limbs muscles were analysed for 1 stroke cycle in each 50 m lap. Capillary blood lactate concentrations were collected before and after the test. The variables of interest were: swimming speed, stroke length, stroke and kick frequency, hand angular velocity, upper limb and foot displacement, elbow angle, shoulder and roll angle, duration of stroke phases, and EMG for each muscle in each stroke phase. Generally, the kinematic parameters decreased, and a relative duration increased for the entry and pull phases and decreased for the recovery phase. Muscle activation of flexor carpi radialis, biceps brachii, triceps brachii, peitoral major and upper trapezius increased during specific stroke phases over the test. Blood lactate concentration increased significantly after the test. These findings suggest the occurrence of fatigue, characterised by changes in kinematic parameters and selective changes in upper limbs muscle activation according to muscle action. [ABSTRACT FROM AUTHOR]

We aimed to determine the effect of sampling interval strategy on ̇VO2max assessment to establish a standard time averaging method that allows a better identification of the ̇VO2 plateau incidence in swimming. To this end, 3 incremental protocols utilizing different step lengths for each sampling interval were used to compare ̇VO2max measurements. 11 trained male swimmers performed 3 repetitions of a front crawl intermittent incremental protocol until exhaustion (increments of 0.05 m.s-1, with 30 s and 24-48 h intervals between steps and tests, respectively) with 200, 300 and 400-m step lengths. ̇VO2 was directly measured, and 6 sampling intervals were compared: bxb and averages of 5, 10, 15, 20 and 30 s. Shorter sampling intervals (≤15 s) allowed the highest incidence of the ̇VO2 plateau, independent of the step lengths used; the 200 and 300-m step protocols accounted for higher percentage of ̇VO2 plateau incidence, and higher ̇VO2max values, compared to the 400-m step protocol. As an optimal sampling interval should be used for the validation of the research findings, and considering that swimmers and coaches prefer less time-consuming protocols, the use of the 10 s time-average interval (once bxb and 5 s samplings present high variability) in a 200-m step incremental protocol for ̇VO2max assessment in swimming is suggested. [ABSTRACT FROM AUTHOR]

We purposed to study energy expenditure, power output and gross efficiency during kayak ergometer exercise in 12 elite sprint kayakers. 6 males (age 24.2 ± 4.8 years, height 180.4 ± 4.8 cm, body mass 79.7 ± 8.5 kg) and 6 females (age 24.3 ± 4.5 years, height 164.5 ± 3.9 cm, body mass 65.4 ± 3.5 kg), performed an incremental intermittent protocol on kayak ergometer with V̇O2 and blood lactate concentration assessment, a non-linear increase between power output and energy expenditure being observed. Paddling power output, energy expenditure and gross efficiency corresponding to V̇O2 max averaged 199.92 ± 50.41 W, 75.27 ± 6.30 ml.kg-1.min-1 , and 10.10 ± 1.08 %. Male kayakers presented higher V̇O2 max, power output and gross efficiency at the V̇O2 max, and lower heart rate and maximal lactate concentration than females, but no differences were found between genders regarding energy expenditure at V̇O2 max. Aerobic and anaerobic components of energy expenditure evidenced a significant contribution of anaerobic energy sources in sprint kayak performance. Results also suggested the dependence of the gross efficiency on the changes in the amount of the aerobic and anaerobic contributions, at heavy and severe intensities. The inter-individual variance of the relationship between energy expenditure and the corresponding paddling power output revealed a relevant tracking for females (FDγ = 0.73 ± 0.06), conversely to the male group (FDγ = 0.27 ± 0.08), supporting that some male kayakers are more skilled in some paddling intensities than others. [ABSTRACT FROM AUTHOR]

Our aim was to determine the 3-dimensional intracycle velocity variation (IVV) of the body centre of mass during a 200-m front crawl event, and to analyse its relation with the segmental hand kinematics and the velocity (v) changes. 10 high-level male swimmers performed a 200-m front crawl swim at maximal intensity. 2 aboveand 4 underwater cameras were used to record one complete non-breathing cycle for each 50-m lap, and APASystem was used for imaging processing. The coeffi cient of variation was calculated to assess the IVV in the horizontal (x), vertical (y), and lateral (z) axes; hand kinematics was also computed. IVV remained stable across the 200 m, and signifi cant correlations were found between vx and vmaxx (r = 0.55), vminx (r = 0.68), IVVx (r = - 0.45), and IVVz (r = - 0.45) (all p ≤ 0.01). In addition, IVVx was correlated with the backward horizontal amplitude normalized to stroke length (r = 0.54), IVVy with hand angular velocity (r = - 0.40), and IVVz with the elbow angle range in the pull phase (r = - 0.37) (all p < 0.05). This study shows the stability of the IVV (x,y,z), the inverse relation of the IVV (x, z) with v, the direct relation of the vmaxx and vminx with v, and the infl uence of the hand kinematics in the IVV [ABSTRACT FROM AUTHOR]

Anaerobic threshold is widely used for diagnosis of swimming aerobic endurance but the precise incremental protocols step duration for its assessment is controversial. A physiological and biomechanical comparison between intermittent incremental protocols with different step lengths and a maximal lactate steady state (MLSS) test was conducted. 17 swimmers performed 7 × 200, 300 and 400 m (30 s and 24 h rest between steps and protocols) in front crawl until exhaustion and an MLSS test. The blood lactate concentration values ([La - ]) at individual anaerobic threshold were 2.1 ± 0.1, 2.2 ± 0.2 and 1.8 ± 0.1 mmol.l -1 in the 200, 300 and 400 m protocols (with significant differences between 300 and 400 m tests), and 2.9 ± 1.2 mmol.l-1 at MLSS (higher than the incremental protocols); all these values are much lower than the traditional 4 mmol.l-1 value. The velocities at individual anaerobic threshold obtained in incremental protocols were similar (and highly related) to the MLSS, being considerably lower than the velocity at 4 mmol.l-1 . Stroke rate increased and stroke length decreased throughout the different incremental protocols. It was concluded that it is valid to use intermittent incremental protocols of 200 and 300 m lengths to assess the swimming velocity corresponding to individual anaerobic threshold, the progressive protocols tend to underestimate the [La - ] at anaerobic threshold assessed by the MLSS test, and swimmers increase velocity through stroke rate increases. [ABSTRACT FROM AUTHOR]