Validity of 2-point method for load-velocity profiling in free swimming, with snorkel, and with added respiratory dead space mask

This study aimed to evaluate the agreement between the 2- and 3-point models in estimating load-velocity (L-v) profile parameters in swimmers; to compare L-v profile parameters of both models across three respiratory conditions: free breathing (FREE), snorkel (SNOR), and added respiratory dead space mask (ARDS); to examine the relationships between L-v profile parameters (from both models) and a 25 m front crawl performance. Twenty-six male swimmers performed three front crawl semi-tethered 20 m sprints at maximal effort with fixed external loads (1, 4, and 7 kg) under three different respiratory conditions, as well as a 25 m front crawl time trial. The raw data were processed using both 2-point and 3-point models to estimate L-v profile parameters. The two-way ANOVA revealed no significant main effect or interaction in the factors for all L-v parameters. Excellent agreement was observed between the 2- and 3-point models across all conditions for all L-v parameters (r ≥ 0.99, R² ≥ 0.98, ICC ≥ 0.99). The 2-point model allows for the assessment of L-v profile parameters as reliably as the 3-point model. The SNOR and ARDS did not affect the L-v profile during swim sprint performance.