Arm coordination in elite backstroke swimmers.

Area of Science:

• Sports Science
• Biomechanics
• Swimming Performance

Background:

• Assessing arm coordination is crucial for optimizing swimming technique.
• The index of coordination, previously used for front crawl, offers a potential metric for backstroke analysis.

Purpose of the Study:

• To adapt and apply the index of coordination to backstroke.
• To analyze changes in arm coordination in elite male backstroke swimmers across different speeds.
• To identify key biomechanical adjustments influencing backstroke performance.

Main Methods:

• Video analysis of elite male backstroke swimmers (n=14) performing 25m trials at varying speeds.
• Calculation of the index of coordination based on the timing between the propulsive phases of each arm.
• Measurement of stroke rate, relative arm pull duration, distance per stroke, and hand lag time.

Main Results:

• Increased swimming speed led to higher stroke rates, longer relative arm pull durations, and increased index of coordination (P < 0.05).
• Distance per stroke decreased significantly with increased speed.
• Backstroke arm coordination consistently exhibited a 'catch-up' pattern (index of coordination: -12.9%), unlike front crawl, due to biomechanical constraints like body roll and shoulder flexibility.
• Hand lag time at the thigh remained constant (~2%) across speeds.

Conclusions:

• The adapted index of coordination effectively quantifies arm coordination in backstroke.
• Elite backstroke swimmers make specific biomechanical adjustments to enhance performance at higher speeds.
• The index of coordination provides a valuable tool for coaches to diagnose and correct coordination issues, particularly concerning hand lag time.