The 2024 Paris Paralympic triathlon required swimming with and against the current which requested to adapt stroke mechanics. To understand how a Paralympic triathlete champion might adapt his stroke mechanics under varying current conditions, this study aimed to 1) determine the range and optimal stroke rate (SR) and index of coordination (IdC); 2) examine the flexibility of SR, IdC and associated total energy expenditure. The para triathlete performed two front crawl tests: 10 times 25m incremented in swimming speed (S), from which S-SR and S-IdC relationships have been modelled to detect two regimes of functioning and the most effective SR; then, 6 times 50 m at the speed of the 800 m freestyle using 6 different SR conditions: spontaneous SR (SR_s), SR_s imposed by tempo trainer, SR_s+3, SR_s+6, SR_s-3 and SR_s-6 cycles. Total energy expenditure was computed from post-exercise oxygen uptake and blood lactate measurements. In test 1, the highest effective SR equals 44 cycle.min^-1, which corresponds to the preferred SR in 800 m freestyle competition. In test 2, the para triathlete struggled to perform the high SR conditions, which was associated to higher total energy expenditure; conversely, the para triathlete naturally decreased SR. It is advised to modulate SR around the preferred SR to optimise efficiency under varying current conditions.

• In the 10 x 25 m test, the para triathlete displayed high and constant SI at low paces suggesting that he could effectively adapt his SR and his arm coordination pattern to swim with the current.

• At high paces, he started losing effectiveness of SR beyond his preferred SR of 44 cycle.min.

• In the 6 x 50 m test modulated in SR, high SR conditions were difficult to achieve and were associated to higher total energy expenditure and higher jerk cost than lower SR conditions.

• Training various SR conditions around the preferred SR allow to functionally adapt arm coordination pattern to favour potential transfer when confronted to the current in ecological context of competition.