Background: Understanding how arm-stroke efficiency (*p) and kinematics respond to stroke rate restrictions helps coaches prescribe effective, task-oriented training. Aim: To investigate the *p and stroke kinematics` responses to manipulated SR conditions in a visually impaired youth swimmer. Methods: This case study adhered to the Declaration of Helsinki and received approval from the institutional Research Ethics Committee (No. 56016616.4.0000.5353). A 14-year-old competitive swimmer at the regional level (body mass: 43.1 kg; height: 1.58 m; arm span: 1.65 m; S12 classification) performed five 25m front crawl sprints at maximum intensity, with 20-minute rest intervals. The conditions included: (1) Free SR; (2) Fixed SR (100% of free SR); (3) Increased SR (110%); and (4) Reduced SR (90% and 80%). The 110%, 90%, and 80% trials were performed in a randomized order. SR was controlled via an underwater metronome (Tempo Trainer, Finis). The *p was estimated using a simplified model. Kinematic variables, as SR, stroke length (SL), swimming speed (SS), stroke index (SI), and 25m time (T25), were analyzed using Kinovea software (2D) at 60 Hz. Above and underwater images of the front crawl stroke were captured by two synchronized cameras (Nikon W300) in the sagittal plane. A manual timekeeper was used to identify the T25. Results: The results highlighted: (i) *p (24.42; 20.12; 17.99; 21.41; 25.11%), SR (69.23; 70.12; 75.72; 62.06; 52.94 cycles.min-1), SL (1.28; 1.25; 1.18; 1.33; 1.56 m), SS (1.47; 1.44; 1.42; 1.37; 1.37 m.s-1), SI (1.89; 1.80; 1.67; 1.83; 2.14 m2.s-1) and T25 (16.87; 17.38; 17.33; 17.83; 18.01 s) under free, fixed, increased, reduced (90% and 80%) SR conditions, respectively. Conclusions: The results of this case study indicate that a reduction in SR led to a compensatory increase in *p, SL, and SI, demonstrating a functional strategy to meet task demands.
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