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This study aimed to examine the relationship between the maximal lactate accumulation rate (ċLamax) and sprint performance parameters in male competitive swimmers. Seventeen male competitive swimmers volunteered to perform a 20 m maximal front crawl sprint without pushing off the wall from a floating position. ċLamax was determined by the 20-m sprint time and blood lactate measured before and after the 20 m sprint. For the sprint performance parameter, a 50 m time trial with the front crawl swimming stroke was conducted, and the times taken from 0 to 15 m, 15–25 m, 25–35 m, and 35–45 m were analyzed. A semi-tethered swimming test was conducted to investigate the load-velocity profile of each swimmer. From the load-velocity profile, theoretical maximal velocity (V0), maximal load (L0) and relative maximal load (rL0) were examined. The slope of the load-velocity profile was also determined. According to the results, ċLamax correlated with 50 m front crawl performance (r = −.546, p <.05). Moreover, a higher ċLamax was related to faster 0–35 m section time. Furthermore, ċLamax correlated with L0 (r =.837, p <.01), rL0 (r =.820, p <.01), and load-velocity slope (r =.804, p <.01). ċLamax is a good indicator of 50 m front crawl performance in male swimmers, and higher glycolytic power contributes to the faster time at the beginning of the sprint race. ċLamax could also evaluate the ability of a swimmer to apply force to the water during high-intensity swimming. [ABSTRACT FROM AUTHOR]

We investigated the effects of jammer-type racing swimsuits (RS) on swimming performance during arm-stroke-only (pull) and whole-body stroke (swim) in 25-m front-crawl with maximal effort. Twelve well-trained male collegiate swimmers wore RS and a conventional swimsuit (CS) and performed three tests: pull, swim, and pull using the system to measure active drag (MAD pull). Swimming velocity and intra-abdominal pressure (IAP) were determined in all tests. Stroke indices during pull and swim and drag–swimming velocity relationship and maximum propulsive power during MAD pull were also determined. Swimming velocities during pull and swim while wearing an RS (1.59 ± 0.13 and 1.77 ± 0.09 m·s−1, respectively) were significantly higher than those wearing a CS (1.57 ± 0.14 and 1.74 ± 0.08 m·s−1, respectively). Stroke length during pull and swim was significantly greater while wearing an RS (1.68 ± 0.12 and 1.83 ± 0.13 m, respectively) than wearing a CS (1.63 ± 0.10 and 1.81 ± 0.13 m, respectively). However, no significant differences were confirmed between the other variables in all tests. In conclusion, swimming performance is improved when wearing an RS compared with a CS. [ABSTRACT FROM AUTHOR]

This study aimed to assess kinematic and kinetic changes in front crawl with various stroke frequency (SF) conditions to investigate why swimming velocity (SV) does not increase above a certain SF (SFmax). Eight male swimmers performed 20 m front crawl four times. The first trial involved maximal effort, whereas SF was controlled during the next three trials. The instructed SFs were 100 (T100%), 110 (T110%), and 120% (T120%) of the SFmax. Through pressure measurement and underwater motion analysis, hand propulsive force (calculated by the difference between the palm and dorsal pressure value and the hand area) and the angle of attack of the hand were quantified, and differences between trials were assessed by a repeated-measures ANOVA. There was no difference in SV between the conditions, while the angle of attack during the latter half of the underwater stroke at T120% was smaller by 25.7% compared with T100% (p = 0.007). The lower angle of attack induced a lower pressure value on the palm that consequently caused a smaller hand propulsive force at T120% than T100% (p = 0.026). Therefore, the decrease in the angle of attack must be minimised to maintain the hand propulsive force. [ABSTRACT FROM AUTHOR]

The aim of this study was to review the literature on front crawl swimming biomechanics, focusing on propulsive and resistive forces at different swimming velocities. Recent studies show that the resistive force increases in proportion to the cube of the velocity, which implies that a proficient technique to miminise the resistive (and maximise the propulsive) force is particularly important in sprinters. To increase the velocity in races, swimmers increase their stroke frequency. However, experimental and simulation studies have revealed that there is a maximum frequency beyond which swimmers cannot further increase swimming velocity due to a change in the angle of attack of the hand that reduces its propulsive force. While the results of experimental and simulation studies are consistent regarding the effect of the arm actions on propulsion, the findings of investigations into the effect of the kicking motion are conflicting. Some studies have indicated a positive effect of kicking on propulsion at high swimming velocities while the others have yielded the opposite result. Therefore, this review contributes to knowledge of how the upper-limb propulsion can be optimised and indicates a need for further investigation to understand how the kicking action can be optimised in front crawl swimming. Abbreviations: C: Energy cost [kJ/m]; Ė: Metabolic power [W, kJ/s]; Fhand: Fluid resultant force exerted by the hand [N]; Ftotal: Total resultant force [N] (See Appendix A); Fnormal: The sum of the fluid forces acting on body segments toward directions perpendicular to the segmental long axis, which is proportional to the square of the segmental velocity. [N] (See Appendix A); Ftangent: The sum of the fluid forces acting on body segments along the direction parallel to the segmental long axis, which is proportional to the square of the segmental velocity. [N] (See Appendix A); Faddmass: The sum of the inertial force acting on the body segments due to the acceleration of a mass of water [N] (See Appendix A); Fbuoyant: The sum of the buoyant forces acting on the body segments [N] (See Appendix A); D: Fluid resistive force acting on a swimmer's body (active drag) [N]; T: Thrust (propulsive) force acting in the swimming direction in reaction to the swimmer's actions [N]; Thand: Thrust force produced in reaction to the actions of the hand [N]; Tupper_limb: Thrust force produced in reaction to the actions of the upper limbs [N]; Tlower_limb: Thrust force produced in reaction to the actions of the lower limbs [N]; Mbody: Whole-body mass of the swimmer [kg]; SF: Stroke frequency (stroke number per second) [Hz]; SL: Stroke length (distance travelled per stroke) [m]; v: Instantaneous centre of mass velocity of the swimmer [m/s]; V ˉ : Mean of the instantaneous centre of mass velocities in the swimming direction over the period of the stroke cycle [m/s]; a: Centre of mass acceleration of the swimmer [m/s2]; V ˉ hand: Mean of the instantaneous magnitudes of hand velocity over a period of time [m/s]; Ẇtot: Total mechanical power [W]; Ẇext: External mechanical power [W]; Ẇd: Drag power (mechanical power needed to overcome drag) [W, Nm/s]; α: Angle of attack of the palm plane with respect to the velocity vector of the hand [deg]; ηo: Overall efficiency [%]; ηp: Propelling efficiency [%]; MAD-system: Measuring Active Drag system; MRT method: Measuring Residual Thrust method. [ABSTRACT FROM AUTHOR]

The purpose of this study was to characterise the unsteady propulsive force during eggbeater kicking by a fluid force estimation method based on pressure distribution analysis. The eggbeater kick was performed by six male water polo players. The participants' eggbeater kicking motions were recorded by three cameras, and the kinematic foot variables were analysed. The pressure distributions around the foot were measured by four pairs of pressure sensors attached to the dorsal and plantar surfaces of the participants' right foot. The resultant fluid force acting on the foot was estimated from the measured pressure and area of the foot. The calculated propulsive force increased with the pressure difference between the plantar and dorsal sides of the foot, which was mainly related to the decrease in pressure on the dorsal side, and peaked when the foot passed its maximum velocity and began to decelerate. These results cannot be elucidated only by conventional biomechanical theories of swimming propulsion (Newton's laws of motion and the quasi-steady approach) but instead indicate a high possibility that the exerted propulsive force is induced by the effects of unsteady water flow. [ABSTRACT FROM AUTHOR]

This study aimed to elucidate the foot kinematics and foot pressure difference characteristics of faster swimmers in undulatory underwater swimming (UUS). In total, eight faster and eight slower swimmers performed UUS in a water flume at a flow velocity set at 80% of the maximal effort swimming velocity. The toe velocity and foot angle of attack were measured using a motion capture system. A total of eight small pressure sensors were attached to the surface of the left foot to calculate the pressure difference between the plantar and dorsal sides of the foot. Differences in the mean values of each variable between the groups were analysed. Compared to the slower swimmers, the faster swimmers exhibited a significantly higher swimming velocity (1.53 ± 0.06 m/s vs. 1.31 ± 0.08 m/s) and a larger mean pressure difference in the phase from the start of the up-kick until the toe moved forward relative to the body (3.88 ± 0.65 kPa vs. 2.66 ± 1.19 kPa). The faster group showed higher toe vertical velocity and toe direction of movement, switching from lateral to medial at the time of generating the larger foot pressure difference in the up-kick, providing insight into the reasons behind the foot kinematics of high UUS performance swimmers. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the essential role of the kicking action in front crawl. To achieve this objective, we examined the relationships of the hand propulsive force and trunk inclination with swimming velocity over a wide range of velocities from 0.75 m·s−1 to maximum effort, including the experimental conditions of arm stroke without a pull buoy. Seven male swimmers performed a 25 m front crawl at various speeds under three swimming conditions: arm stroke with a pull buoy, arm stroke without a pull buoy (AWOB) and arm stroke with a six-beat kick (SWIM). Swimming velocity, hand propulsive force and trunk inclination were calculated using an underwater motion-capture system and pressure sensors. Most notably, AWOB consistently exhibited greater values than SWIM for hand propulsive force across the range of observed velocities (p < 0.05) and for trunk inclination below the severe velocity (p < 0.05), and these differences increased with decreasing velocity. These results indicate that 1) the kicking action in front crawl has a positive effect on reducing the pressure drag acting on the trunk, thereby allowing swimmers to achieve a given velocity with less hand propulsive force, and 2) this phenomenon is significant in low-velocity ranges. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the effect of the flutter kick on the propulsive force generated by a stroke. Eight male swimmers performed 20 m front crawl trials under two conditions: the Whole Condition, involving maximum effort (T100%) and stroke frequencies at 70, 80, and 90% of T100%, and the Arm Condition, which excluded the flutter kick and matched stroke frequencies with the Whole Condition. Various parameters, including swimming velocity, stroke frequency, stroke length, three-dimensional (3D) resultant hand speed, and hand propulsion were calculated based on underwater 3D motion analysis and hand pressure distribution measurements. A two-way repeated-measures ANOVA was conducted to assess differences, considering the conditions and instructed frequencies as the two factors. There was no significant interaction between the condition and intensity for any of the variables. There was a significant main effect of condition on swimming velocity and stroke length, with these variables being 16.9–18.5% higher and 17.3–19.5% longer, respectively, in the Whole Condition compared to the Arm Condition. However, there was no difference in hand propulsion between the conditions, and it was clarified that the flutter kick did not affect hand propulsion at any swimming velocity. [ABSTRACT FROM AUTHOR]