Effect of an 8-week technical tethered swimming program on entrance kinematics in adolescent swimmers

Participants

Nineteen women (age 13.18 ± 0.66 years; physique top 163.6 ± 5.2 cm; physique weight 50.8 ± 4.42 kg; physique fats 20.5% ± 2.0%) and 20 boys (age 13.33 ± 0.60 years; physique top 167.8 ± 8.76 cm; physique weight 52.46 ± 8.8 kg; physique fats 14.1% ± 2.3%) participated within the research. All topics had been athletes of an area sports activities membership. Inclusion standards had been: age between 12 and 14 years, possession of a legitimate swimming license, common participation in competitions organized by the Polish Swimming Federation, and a minimal of two years of systematic swimming coaching. Exclusion standards included musculoskeletal accidents within the 3 months previous the research, medical contraindications for high-intensity coaching. Written knowledgeable consent was obtained from all members and their authorized guardians.

Participants had been randomly allotted to the experimental group (EG) or management group (CG) utilizing a computer-generated randomization process in Microsoft Excel. The randomization checklist was created previous to the beginning of the intervention.

The research was accredited by the Senate Committee on Research Ethics of the Józef Piłsudski Academy of Physical Education in Warsaw (SKE 01–31/2023). All procedures involving human members had been carried out in accordance with related tips and rules, and in adherence to the Declaration of Helsinki. Informed consent was obtained from all members and, because of the age of the themes, from their mother and father or authorized guardians. Participants and their authorized guardians had been absolutely knowledgeable concerning the nature, goal, and course of the research, together with any potential dangers or advantages related to participation.

Sample measurement and willpower

The required pattern measurement was estimated a priori utilizing GPower software program. For a repeated-measures ANOVA, assuming a medium impact measurement (Cohen’s f = 0.25), α = 0.05, and desired statistical energy (1–β) = 0.80, the minimal pattern measurement was calculated as 34 members (17 per group). Our last pattern of 39 members exceeded this threshold, making certain satisfactory statistical energy to detect significant interplay results.

Procedure

The research members had been randomly divided into two teams, in every sustaining gender parity. Randomization was carried out utilizing an Excel operate. In the experimental group (EG), extra tethered technical coaching was launched. At this time, the management group (CG) carried out customary technical coaching in free swimming. The research included an 8-week coaching cycle.

Additional technical tether swimming was carried out as soon as per week and lasted 45 min. It included the next coaching process:

6 × 10 tethered swimming crawl cycles with 10ʹʹ relaxation,

1 × 150 entrance crawl snorkel swimming.

The athletes carried out technical coaching in a tether with a snorkel to facilitate respiration. Free swimming was additionally carried out with a snorkel to standardize coaching strategies. The principal goals of performing this process had been:

1. 1.

   Focusing on the size of the stroke.

2. 2.

   Deliberately gradual execution of actions.

3. 3.

   Stabilizing the trunk by decreasing lateral arm motion.

4. 4.

   Low-intensity work, maintained beneath the cardio threshold

At the identical time, the management group (CG) carried out technical coaching for entrance crawl, following an an identical schedule and technical tips because the experimental group (EG), and it concluded with a trending process:

45 min (x50 relaxation 10ʹʹ−20ʹʹ).

1. 1.

   One-arm entrance crawl

2. 2.

   Catch-up stroke drill

3. 3.

   One-arm alternate catch-up

4. 4.

   Front crawl

Both exercises had been instructed and coordinated by two skilled swimming coaches (stage I – licensed by Polish National Swimming Association).

Before and after the break up, the entire group carried out the identical swimming coaching collectively. The break up was solely launched through the 45 min of coaching described above.

Training load throughout TTS was monitored utilizing tether power measurement, coronary heart charge (Polar Verity Sense), and the Children’s OMNI Scale of Perceived Exertion, with the goal depth set beneath 150 bpm. The goal of the duty was defined to the swimmers earlier than every coaching bout, and through its execution the coaches centered solely on controlling depth and length. No extra technical suggestions was supplied, as two coaching classes had been carried out in parallel, and it was necessary to make sure that neither group obtained preferential consideration.d.

Pre-test and post-test included:

1. 1.

   Measurement of top and weight.

2. 2.

   Measurement of the time taken to swim a distance of fifty m in entrance crawl at most velocity whereas measuring acceleration utilizing an accelerometer positioned on the again of the pelvic girdle. Plenty of variables had been measured in 3 main physique actions:

• Translational movement – represented by averaged acceleration alongside the vertical axis.

• Body roll (rotational actions across the vertical axis of the physique) – recorded by velocities across the vertical axis.

• Yaw rotation (rotational actions across the sagittal axis) recorded by angular velocities across the sagittal axis and accelerations alongside the transverse axis.

The evaluation presents probably the most related variables, whose values are averaged.

The most related variables had been chosen for evaluation, and the values introduced had been averaged.

From the recorded knowledge, common numerical values of the swimming cycle had been calculated, together with arithmetic means and customary deviations for relative time (relative to cycle length), all measured from the start of the cycle. These calculations had been carried out utilizing STA1v0 software program (Zbigniew Staniak, Institute of Sport – National Research Institute, Poland).

The following elements had been measured and analysed: av_max – vertical acceleration throughout propulsion, ω_maxR – angular velocity across the vertical axis in rolling actions, ω_maxY – angular velocity across the sagittal axis in yaw rotation, and A_maxR – most angle of pelvic tilt across the vertical axis throughout rotational actions. The knowledge had been analysed individually for actions involving the left higher limb (Left) and proper higher limb (Right), in addition to for the primary lap (I25) and the second lap (II25).

The chosen kinematic variables had been chosen as a result of they signify crucial facets of trunk rotation and stability in entrance crawl swimming. Roll angle and angular velocity have been broadly investigated as indicators of physique alignment and hydrodynamic effectivity^26,27. In distinction, yaw actions have obtained a lot much less consideration in swimming analysis, with only some research addressing this variable lately. In our view, yaw rotation is an unjustly uncared for facet of swimming kinematics, because it straight displays trunk management and lateral deviations which will improve drag and impair effectivity. Including yaw among the many analyzed variables subsequently gives a broader and extra complete image of swimmers’ physique alignment.

The measurements passed off in a 25 m pool. The athletes began from the water (with out a beginning dive). They swam the 25 m entrance crawl, did the usual freestyle turnaround and swam the second lap of the 50 m distance. The topics had been requested to finish the duty within the shortest potential time. Before beginning the swim, they carried out a begin warm-up consisting of a 1200 m swim as detailed by Skorulski et al.²⁸.

Research devices

For every swimmer, the person traits of the kinematics of common hip motion through the first and second halves of the pool had been decided. A recorder (REJ62g by JD Jarosław Doliński, Poland) was used to trace modifications in velocity and acceleration. The machine contained a triaxial gyroscope and triaxial accelerometer (65 × 50 × 30 mm, 95 g). It was positioned in a foam cowl to minimise hydrodynamic drag and supply stability within the swimmer’s decrease again, close to the pelvic girdle. The centre of the recorder was aligned on the base of the sacrum. A particular two-part belt was used to safe it: a non-elastic rope connected the recorder, whereas an elastic band was positioned on the swimmer’s decrease stomach (Fig. 1).

The pelvic area was chosen for sensor placement as a result of it represents the central hyperlink in trunk alignment and power switch throughout swimming. Previous analysis has proven that pelvic yaw and roll are delicate indicators of trunk stability and hydrodynamic effectivity, with extreme rotation related to elevated drag and optimized rotation linked to improved swimming efficiency^26,29.

Measurements had been taken at a sampling frequency of 200 Hz, with acceleration measured inside a spread of ± 2 g. The sign underwent analogue low-pass filtering at a cutoff frequency of 93 Hz. To measure angular velocity throughout rotation, a spread of ± 500 deg·s⁻¹ was used.

The accuracy of acceleration measurements was verified statically in opposition to floor acceleration, with an absolute error of ± 0.2 m·s⁻². The precision of angular velocity readings was checked not directly by measuring and calculating the recorder’s rotation angle inside a 90-degree vary round every axis. The absolute error for angle calculation was ± 1 diploma, and for angular velocity, it was ± 0.6 deg·s⁻¹.

The validity of this machine for swimming kinematics has been demonstrated beforehand: Staniak et al³⁰. confirmed its capability to tell apart breaststroke cycles as compared with video-based reference evaluation, whereas Staniak et al³¹. reported its sensitivity to part length and correlation with efficiency in butterfly, additionally validated in opposition to high-speed video. More lately, Skorulski et al²⁸. confirmed that the machine can detect fatigue-induced modifications in entrance crawl, confirming technical sensitivity.

The recorded waveforms had been smoothed utilizing a four-pole low-pass Butterworth filter with a cutoff frequency of 20 Hz. This frequency was chosen to make sure that the calculated amplitude of movement velocity wouldn’t lower by greater than 0.5% because of filtering, whereas protecting necessary acceleration waveform factors for motion evaluation clearly seen.

Body weight and composition had been measured utilizing a Tanita BC-545 N scale (Tanita Corporation, Tokyo, Japan).

A tether with a power meter (ZPS5-BTU1kN, Staniak, Poland) recorded the pulling power at 100 Hz and despatched the information to a pc program for additional evaluation (MAX6v0M software program, Poland).

During coaching, the check topics had been monitored utilizing Polar Verity sense sensors, which permit real-time measurement of coronary heart charge utilizing Polar Team software program. After a process, every athlete was requested to charge the duty utilizing the Children’s OMNI Scale of Perceived Exertion (OMNI) (Robertson et al., 2000).

Heart charge and fatigue ranges had been monitored by skilled swim coaches utilizing the PolarTeam app and Variety Sense sensors. The goal of the coaching was to maintain the center charge beneath 150 h (bpm). The athletes had already been launched to the OMNI scale and to working with coronary heart charge sensors.

Test topics performing tethered technical swimming had been subjected to pulling power measurements throughout technical work to find out the utmost power with which they carried out the technical process. A tether with a power meter (ZPS5-BTU1kN, Staniak, Poland) recorded the pulling power at 100 Hz and despatched the information to a pc program for additional evaluation (MAX6v0M software program, Poland).

Test topics performing technical tethered swimming had been subjected to a thrust measurement throughout technical work to find out the utmost power with which they carried out the technical process.

Training quantity and depth

The coaching was designed and carried out by the trainers in command of the research coaching group. The construction of the coaching used is proven in Table 1.

Statistical evaluation

Statistical analyses had been carried out utilizing STATISTICA software program, model 13.1 (TIBCO Software Inc., 2017). The Kolmogorov-Smirnov check was used to confirm the normality of knowledge distribution, with a p-value better than 0.20 indicating a traditional distribution. All examined variables met the belief of normality.

To assess variations in means, a repeated measures ANOVA (common linear mannequin) was used. The evaluation included three within-subject elements: MEASUREMENT (pretest, posttest), LAP (first, second), and SIDE (left, proper), whereas GROUP (experimental, management) was handled as a between-subject issue. Post-hoc analyses had been carried out utilizing Fisher’s least important distinction (LSD) check. Statistical significance was set on the stage of α = 0.05. Data had been reported as means ± customary deviations and accompanied by 95% confidence intervals. Effect sizes had been estimated utilizing partial eta squared.