Mastering a Scorching Course

The weather conditions at Ironman 70.3 Vietnam were brutal – the temperature reached 36° C/97° F with 60% humidity during the run. But CORE Coach Sang Whan Oh (@tri_sang_oh) mastered the course, wining his 50–54 age group and taking 5th amateur overall. How did he do it? Heat training, cooling measures, and heat-compensated pacing.

Sang operates The Cycle Park in Busan, South Korea, where the daily high temperatures in the month before the race averaged 20° C/68° F. So, adaption to the heat was critical to race-day success. Sang began heat training 6 weeks before the race.

Once a week he did an indoor cycling session that included 40 minutes in his heat training zone. And two times a week, immediately following a training session where his core temp was elevated into the heat training zone, he would soak in a 40° C/104° F hot tub for 15–20 minutes. He would sweat more than 1 litre in the hot tub, and he described the soak as ‘very uncomfortable’.

During the race, Sang aspired to keep his core temp below 40° C/104° F. He did so by first keeping his core temp below 39° C/ 102° F during the bike, knowing that it would rise during the run. During the run, he used the cooling strategies of pouring water over his body, wearing a water-soaked cap, and putting ice into his tri suit.

He also employed heat-compensated pacing – slowing his pace to keep his core temp below 40° C/104° F. Even so, he ran a 1:32 half marathon and passed the one-time race leader who had resorted to walking.

The heat of the race, and his strong effort, are reflected in his Heat Strain Index, which stayed around 4–5 for the bike and 7–8 during the run. His total Heat Strain Score for the day was 3752. Sang discussed these very difficult conditions during the run. “I felt a light stomach ache which often occurs when I’m too sweaty and hot. And a light trembling of the arms happened after 1 hour. The trembling of arms occurs in hot tub training, and it is difficult to endure there. So, I concentrated more on my temperature on my watch. After the race I got a cramp in my lower leg.”

Sang reflected on his preparation and his race: “CORE helps me not suffer under the strong sun. After the race, I had no fatigue, so I could immediately continue my training. Last weekend I won overall in a local triathlon and someone stated that my best performance happened after the age of 50. Absolutely CORE helped me to achieve this performance and I am looking forward to having a good result at Challenge Gunsan-Saemanguem in June.”