# Kinematic Comparison of Different Types of Start Technique in Bi-Finswimming

## TL;DR

This study compares different start techniques in Bi-Finswimming and finds that the kick start performs better than the grab start.

## Contribution

The study provides empirical evidence on the performance differences between grab and kick start techniques in Bi-Finswimming.

## Key findings

- Kick start techniques showed faster 5m, 15m, and 25m times compared to grab start.
- Grab start had longer block time but shorter flight time than kick start.
- Faster times in kick start were linked to increased flight distance and longer flight time.

## Abstract

Objective: This study aimed to experimentally investigate the biomechanical and performance differences between the grab start (GS) and the kick start (KS) with each leg on the kickplate (KSR, KSL) in Bi-Finswimming (BFS). It focused on the effect of foot placement on the starting block, equipped with an adjustable, inclined rear kickplate (Omega, OSB11), to determine potential performance advantages and contribute evidence-based recommendations for optimizing start techniques in competitive BFS. Methods: Thirteen national-level finswimmers (seven males, six females; age: 17.7 ± 2.1 years) voluntarily participated. Each athlete performed two trials of three start techniques (GS, KSR, KSL) over three days in a randomized order. Four synchronized cameras recorded video data. Performance metrics (time to 5 m (T5), 15 m (T15), 25 m (T25), reaction time, block time (BT), flight time (FT), and entry characteristics) along with joint angles (hip, knee, ankle), were analyzed using Kinovea software (v. 2024.1). A two-way repeated measures ANOVA (start type × gender) was conducted to analyze performance metrics, and a paired-sample t-test assessed differences in joint angles. Also, correlations between dependent (type of start) and independent variables (start-examined variables) were examined through bivariate Pearson’s r analysis. Results: No significant gender differences were found (p > 0.05). Significant differences emerged between the starting techniques, with KS showing faster T5, T15, and T25 (p < 0.001, η2p = 0.6; p < 0.001, η2p = 0.5; p < 0.05, η2p = 0.3, respectively). BT was significantly longer in GS compared to KS (p < 0.001, η2p = 0.8), while FT was shorter in GS (p = 0.002, η2p = 0.4). Faster T5, T15, and T25 were associated with increased flight distance and longer FT in KSL. Conclusions: The kick start generally outperforms the grab start, especially in block time, in Bi-Finswimming. These preliminary results suggest that it could be considered for future discussion regarding potential legalization by the World Underwater Federation, pending further research.