Intra- and inter-cycle velocity variations in sprint front crawl swimming

Velocity Variability and Performance in Backstroke in Elite and Good-Level Swimmers

“…In a 1.90 m, deep 25 m long indoor swimming pool with a 27 °C water temperature, and after a standardized warm-up [ 2 ], swimmers were video recorded while performing 25 m backstroke at maximal intensity. An underwater and an aerial camera (Go Pro 6, San Mateo, CA, USA), operating at 120 Hz sampling frequency, with 1920 × 1080 pixels resolution in wide mode, were fixed to a camera set-up in the sagittal plane and pushed alongside the pool [ 2 ]. Ten markers rows were placed on the pool floor (with a 2.5 m distance in between each one), allowing subsequent calibration and coordinates transformation ( Figure 1 ) [ 2 ].…”

“…An underwater and an aerial camera (Go Pro 6, San Mateo, CA, USA), operating at 120 Hz sampling frequency, with 1920 × 1080 pixels resolution in wide mode, were fixed to a camera set-up in the sagittal plane and pushed alongside the pool [ 2 ]. Ten markers rows were placed on the pool floor (with a 2.5 m distance in between each one), allowing subsequent calibration and coordinates transformation ( Figure 1 ) [ 2 ].…”

“…Swimming is a cyclic sport that displays a repeating structure due to the continuous action of the limbs. However, swimming also presents biomechanical variability in each one of the conventional propulsive techniques, demonstrating similar but not identical consecutive cycles [ 1 , 2 ]. Many environmental-, individual-, and task-related perturbations modify the ongoing movement dynamics and are considered inherent biological noise.…”

“…Variability in cyclic movements is a very well-studied topic in sport sciences, especially in swimming, where researchers and coaches focus on intracycle velocity [ 2 , 5 ] and force variations [ 6 , 7 ], upper- and inter-limb coordination variability [ 8 , 9 ], stroke rate and stroke length inter-lap variability [ 10 ], electromyography [ 5 , 11 ], and body segments [ 12 , 13 ]. These approaches often use standard deviation, coefficient of variation and mean difference statistical measures to quantify variation, but it is the structure of the variability (not only its magnitude) that is important to better understanding good versus bad performances.…”

“…The literature presents conflicting results about intra-cyclic velocity variation (commonly assessed using the coefficient of variation), showing both higher and lower values in elite swimmers compared to their lower-level counterparts. However, a lower intra-cyclic velocity variation should produce a more efficient swim for the same drag condition [ 2 , 13 ]. These conflicting data might be explained by individual differences in drag profile and might not be directly related to the velocity variation itself.…”