Abstract
The present study aimed to explore the variability of the arm-stroke temporal descriptors between and within laps during middle-distance swimming event using IMMUs. Eight male swimmers performed a 200-m maximum front-crawl in which the inter-lap and intra-lap variability of velocity, stroke rate, stroke-phases duration and arm-coordination index were measured through five units of IMMU. An algorithm computes the 3D coordinates of the wrist by means the IMMU orientation and the kinematic chain of upper arm biomechanical model, and it recognizes the start events of the four arm-stroke phases. Velocity and stroke rate had a mean value of 1.47 ± 0.10 m·s−1 and 32.94 ± 4.84 cycles·min−1, respectively, and a significant decrease along the 200-m (p < 0.001; η2 = 0.80 and 0.47). The end of each lap showed significantly lower stroke rate compared to the start and the middle segment (p < 0.05; η2 = 0.55). No other significant inter-lap and intra-lap differences were detected. The two main findings are: (i) IMMUs technology can be an effective solution to continuously monitor the temporal descriptors during the swimming trial; (ii) swimmers are able to keep stable their temporal technique descriptors in a middle-distance event, despite the decrease of velocity and stroke rate.
Highlights
IntroductionA variety of motion capture methods were used to assess the kinetics and kinematics of swimming
In previous research, a variety of motion capture methods were used to assess the kinetics and kinematics of swimming
An increase in stroke rate can lead to an increase in swimming speed and performance [28]. These findings suggest and support that the management of the stroking parameters is a key aspect of performance that coaches should consider when designing training
Summary
A variety of motion capture methods were used to assess the kinetics and kinematics of swimming. The reference method is three-dimensional videobased analysis [1,2]. Video analysis of swimming performance has shown high accuracy and effectiveness, it has some limitations like short capture periods, elaborate setting process and extensive data processing [3,4]. Swimming velocity (v) is a key factor when assessing swimming performance. According to Figuereido et al [11], in a 200-m front crawl race, the inter-lap SR develops a U-shaped manner with a smooth increase at the end of the effort, to compensate the decrease in SL due to augmented effort when attempting to maintain a constant speed. The swimmers adjust v by adapting their SR, since an almost even pace is optimal for 200-m swimming performance across all strokes [12]
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