Thomas Heilman Fires Off 50.70 In 100 Fly To Break His Own 17-18 NAG Record From Prelims

2025 U.S. NATIONAL CHAMPIONSHIPS

• Tuesday, June 3 – Saturday, June 7, 2025
• Indianapolis, Indiana
• Indiana University Natatorium
• LCM (50 meters)
• World Championship Selection Criteria
• SwimSwam Preview Index
• Meet Central
• Psych Sheets (Updated 6/02)
• Live Results
• How To Watch (USA Swimming Network)
• Prelims Live Recap: Day 1 | Day 2 | Day 3
• Finals Live Recap: Day 1 | Day 2 | Day 3

Thomas Heilman delivered another standout performance on day three of the 2025 U.S. National Championships, which also serves as the qualifying meet for this summer’s World Championships in Singapore. The 18-year-old finished 2nd in the 100 butterfly, securing a new National Age Group (NAG) record of 50.70 in the final, which ranks him 6th fastest man in the world so far this season.

Tonight’s swim marks his third foray under the 51-second barrier. His previous two came in the form of a 50.80 at last summer’s Olympic Trials, where he also placed 2nd, and his earlier 50.78 from prelims this morning, which stood as the NAG record until his finals swim overtook it.

The future Virginia Cavalier’s improvement stemmed solely from the first 50 meters, as he opened 0.14 ahead of his previous pace before closing just 0.06 slower. See a full splits comparison between all three of his sub-51 swims below.

Split Comparison:

Heilman, still only 18, remains the second-fastest 18-and-under swimmer in history in the event. He sits just eight hundredths behind Hungary’s Kristof Milak, the 200 fly world record holder and Tokyo Olympic gold medalist in that event. Milak also took silver in the 100 fly in Tokyo before flipping the script in Paris, where he won gold in the 100 and silver in the 200.

All-Time Performers, Boys’ 17-18 100 Butterfly (LCM):

1. Kristof Milak (HUN), 50.62 – 2017
2. Thomas Heilman (USA), 50.70 – 2025
3. Andrei Minakov (RUS), 50.83 – 2019
4. Josif Miladinov (BUL), 50.93 – 2021
5. Li Zhuhao (CHN), 50.96 – 2017
6. Michael Phelps (USA), 51.10 – 2003
7. Egor Kuimov (RUS), 51.16 – 2017
8. Ilya Kharun (CAN), 51.22 – 2023
9. Kaii Winkler (USA), 51.51 – 2024
10. Hubert Kos (HUN), 51.52 – 2021

In tonight’s race, Texas pro Shaine Casas wasted no time asserting control from the very start, blasting out in 23.40 over the opening 50 meters. Heilman followed closely behind in 2nd (23.76), while Dare Rose, the bronze medalist in the 100 2023 World Championships in Fukuoka, kept himself within striking distance with his 23.85 split.

Heilman made a strong push coming off the turn, surging through the middle of the final 50 meters, while Rose began to charge as well. But Casas held firm, splitting 27.11 on the back half to fend off both challengers and collect his first national title of the meet. His winning time of 50.51 was just 0.11 off his personal best of 50.40 and ranks as the fourth-fastest time in the world this year.

Rose, coming off a win in the 50 fly on Day 2, touched 3rd in 51.06. While Casas and Rose are guaranteed spots on this summer’s World Championship team due to their 1st place finishes, Heilman will have to wait, as the roster limit may become a concern.

After qualifying for his first Olympic team at last summer’s Trials in the 100 and 200 butterfly, Heilman went on to compete in both events in Paris. He secured 10th in the 200 fly with a time of 1:54.87, advancing to the semifinals but missing the final. In the 100 fly, he missed out on a second swim entirely, adding over a second to his Trials best and finishing 18th in 51.82.

Heilman still walked away from Paris with an Olympic medal, earning silver as a prelim swimmer on the 4×100 medley relay.

Those results followed a strong showing at the 2023 World Championships, where he finished 4th in the 200 fly (1:53.82) and 17th in the 100 fly (51.66), while also notching a gold medal for swimming a prelim leg on the men’s 4×100 medley relay.

The 100 fly is Heilman’s only 17-18 NAG record in the long course pool, though he owns the 15-16 marks in the 100 fly (51.19) and 200 fly (1:53.82), plus the 13-14 records in the 50 free (22.95), 100 free (51.12) and 100 fly (53.27) in LC.

This past December, he reset the boys’ 17-18 NAG records in the short course 100 fly (43.86) and 200 fly (1:38.95) at the 2024 Winter Junior Championships – East.

Tonight’s Race Video 

Courtesy: USA Swimming