Load-Velocity Profile and Active Drag in Young Female Swimmers: An Age-Group Comparison.

PURPOSE: The present study aimed to establish differences in load-velocity profiling, active drag (AD), and drag coefficient (Cd) between 3 age groups of female swimmers. METHODS: Thirty-three swimmers (11, 13, or 16 y old) were recruited. The individual load-velocity profile was determined for the 4 competitive swimming strokes. The maximal velocity (V0), maximal load (L0), L0 normalized to the body mass, AD, and Cd were compared between the groups. A 2-way analysis of variance and correlation analysis were conducted. RESULTS: Compared with their younger counterparts, 16-year-old swimmers generally had larger V0, L0, and AD, which was particularly evident when comparing them with 11-year-old swimmers (P ≤ .052). The exception was breaststroke, where no differences were observed in L0 and AD and Cd was smaller in the 16-year-old group than the 11-year-old group (P = .03). There was a negative correlation between Cd and V0 for all groups in backstroke (P ≤ .038) and for the 11-year-old group and 13-year-old group in breaststroke (P ≤ .022) and front crawl (P ≤ .010). For the 16-year-old group, large correlations with V0 were observed for L0, L0 normalized to the body mass, and AD (P ≤ .010) in breaststroke and for L0 and AD with V0 in front crawl (P ≤ .042). In butterfly, large negative correlations with V0 were observed in the 13-year-old group for all parameters (P ≤ .027). CONCLUSIONS: Greater propulsive force is likely the factor that differentiates the oldest age group from the younger groups, except for breaststroke, where a lower Cd (implying a better technique) is evident in the oldest group.

The gold rush in para swimming: changes in the speed curve of a visually impaired world and paralympic champion - a case study.

This case study examined the association between 50 m freestyle and speed curve parameters of a world-class Paralympic swimmer and analysed the changes in speed curves and their frequency components across her performance levels. From 2018 to 2021, a visually impaired female swimmer (26.59 s in 50 m freestyle, S12 class) underwent 22 tests to obtain instantaneous speed synchronised with video recording. She regularly performed 50 m freestyle in competitions and time trials. The fast Fourier transformation method converted the speed signal into frequency domains and determined the relative contribution of the harmonics with two maxima and minima (H2, arms actions) and six maxima and minima (H6, legs actions). The functional paired t-test compared the speed curves at the beginning (PRE) and end (POST) of the analysed period. The 50 m freestyle time correlated with average speed (r = -0.50, p = 0.02). The contribution of H6 increased in the first year and remained large, whereas the contribution of H2 was lower throughout the whole period. POST was faster than PRE in five moments that coincide with the downward leg kick moments. These changes allowed her to stay longer at the upper part of the curve and improve performance over time.

Arm-leg coordination during the underwater pull-out sequence in the 50, 100 and 200 m breaststroke start.

OBJECTIVES: To investigate the arm-leg coordination from different perspectives of motor control during the underwater start sequence to understand whether differences exist between the three competitive breaststroke swimming events. DESIGN: Cross-sectional study. METHODS: Forty-one breaststroke races (with race times relative to the world record): 50-meter (n = 14, 87.6%), 100-meter (n = 14, 88.5%) and 200-meter (n = 13, 85.4%) were recorded. A race analysis system tracked the two-dimensional displacement of the head. Key points from the underwater start sequence were obtained from notational analysis in order to compute seven time-gaps and four phases to assess the arm-leg coordination and timing of the dolphin kick. A one-way ANOVA with Bonferroni post-hoc correction was used to assess differences between the time gaps and phases for the three events. RESULTS: Differences between the three events were found for total underwater glide, and the first (T0) and second (T1) major glide phase. No differences between the events were found in relative duration and distance for the time gaps related to arm-leg coordination (T1-3, T4, T6) and timing of the dolphin kick (T4-5) during the underwater start sequence. CONCLUSIONS: The arm-leg coordination and timing of the dolphin kick showed no difference between the events, but the total underwater glide duration was longer in both the 100- and 200-meter compared with the 50-meter start. This shows that swimmers did not change the complex inter-limb coordination between the competitive events, but only modified the least complex movement, gliding, to adapt to the swimming speed of the respective events.

The Relationship Between Selected Load-Velocity Profile Parameters and 50 m Front Crawl Swimming Performance.

The purpose of the present study was to establish relationships between sprint front crawl performance and a swimming load-velocity profile. Fourteen male national-level swimmers performed 50 m front crawl and semi-tethered swimming with three progressive loads. The 50 m performance was recorded with a multi-camera system, with which two-dimensional head displacement and the beginning of each arm-stroke motion were quantified. Forward velocity (V50m), stroke length (SL) and frequency (SF) were quantified for each cycle, and the mean value of all cycles, excluding the first and last cycles, was used for the analysis. From the semi-tethered swimming test, the mean velocity during three stroke cycles in mid-pool was calculated and plotted as a function of the external load, and a linear regression line expressing the relationship between the load and velocity was established for each swimmer. The intercepts between the established line and the axes of the plot were defined as theoretical maximum velocity (V0) and load (L0). Large to very large correlations were observed between V50m and all variables derived from the load-velocity profiling; L0 (R = 0.632, p = 0.015), L0 normalized by body mass (R = 0.743, p = 0.002), V0 (R = 0.698, p = 0.006), and the slope (R = 0.541, p < 0.046). No significant relationships of SL and SL with V50m and the load-velocity variables were observed, suggesting that each swimmer has his own strategy to achieve the highest swimming velocity. The findings suggest that load-velocity profiling can be used to assess swimming-specific strength and velocity capabilities related to sprint front crawl performance.

Long-term changes in the speed curve of a world-class butterfly swimmer.

This study describes the changes in selected points of the speed curve, stroke rate (SR), and stroke length (SL) of an elite butterfly swimmer and examines their relationship with average speed (AS) and competitive performance. Over eight years, a male swimmer (50 and 100 m: 22.70 and 51.47 s) underwent 18 tests to assess AS, SR, SL, intracyclic speed variation (ISV), and eight selected points of the speed curve. Peak1 is the maximum speed in the upward kick executed during the arm recovery; peak2 is the maximum speed in the first downward kick after the arm entered into the water; peak3 is the maximum speed during the arm pull; and peak4 is the maximum speed during the arm push combined with the second downward kick. Min1, min2, min3, min4 corresponds to the minimum speeds found respectively before each peak speed. Official competitive results in 50 (50BF) and 100 m (100BF) within three weeks of the speed tests were registered. SR (r=0.736), ISV (r=-0.493), peak1 (r=0.555), min2 (r=0.558), and min3 (r=0.539) were correlated with AS. 50BF was correlated with AS (r=-0.658) and peak1 (r=-0.820), whereas 100BF with AS (r=-0.676), SR (r=-0.571), peak1 (r=-0.758), and peak2 (r=-0.594). AS increased by improving SR, peak1 and peak3. Increases in min2 and min3 indicate better transitions from resistive to propulsive phases. Selected points of the speed curve may predict butterfly performance.

Different Muscle-Recruitment Strategies Among Elite Breaststrokers.

PURPOSE: To investigate electromyographical (EMG) profiles characterizing the lower-limb flexion-extension in an aquatic environment in high-level breaststrokers. METHODS: The 2-dimensional breaststroke kick of 1 international- and 2 national-level female swimmers was analyzed during 2 maximal 25-m swims. The activities of biceps femoris, rectus femoris, gastrocnemius, and tibialis anterior were recorded. RESULTS: The breaststroke kick was divided in 3 phases, according to the movements performed in the sagittal plane: push phase (PP) covering 27% of the total kick duration, glide phase (GP) 41%, and recovery phase (RP) 32%. Intrasubject reproducibility of the EMG and kinematics was observed from 1 stroke cycle to another. In addition, important intersubject kinematic reproducibility was noted, whereas muscle activities discriminated the subjects: The explosive PP was characterized by important muscle-activation peaks. During the recovery, muscles were likewise solicited for swimmers 1 (S1) and 2 (S2), while the lowest activities were observed during GP for S2 and swimmer 3 (S3), but not for S1, who maintained major muscle solicitations. CONCLUSIONS: The main muscle activities were observed during PP to perform powerful lower-limb extension. The most-skilled swimmer (S1) was the only 1 to solicit her muscles during GP to actively reach better streamlining. Important activation peaks during RP correspond to the limbs acting against water drag. Such differences in EMG strategies among an elite group highlight the importance of considering the muscle parameters used to effectively control the intensity of activation among the phases for a more efficient breaststroke kick.