King won under the sweltering rays of the August sun having escaped a nine strong breakaway group - taking with him Jelle Wallays (Lotto-Soudal) and Nikita Salnov (Astana).
It was Salnov who worked with King on the final climb, Wallays dropping off the pace and leaving the Dimension Data rider to go into stalking-panther mode in the final kilometre, pouncing from the Astana rider's wheel to cross the line solo.
King's Dimension Data team have revealed that his preparation included sweating it out on Zwift in an enclosed space, surrounded by electric fan heaters which maintained the room at around 35°C - in order to establish his response to the heat and therefore the hydration required to perform.
"With the Vuelta starting in southern Spain, the forecast for the opening week of the race was always likely to present the riders with hot environmental conditions, over 30°C", explained Dave Nichols, coach and sport scientist at Team Dimension Data for Qhubeka.
Nichols is a PhD candidate at Aspetar Sports Medicine Hospital in Qatar, specialising in the physiology of heat acclimatisation and repercussions on cycling performance.
"It is well documented that endurance performance is impaired in warm environments. Training in the heat is the best strategy to offset this performance detriment as the body rapidly undergoes many physiological adjustments to better cope in this environment, even in as few as five days," he said.
"Whilst Ben’s specific heat training was completed outside using the natural environment at his home base in Lucca, we also used this opportunity to test his physiological responses to the heat in an artificial environment in the team’s service course."
King wasn't the only Dimension Data rider subjected to the test chamber.
The riders completed an hour long pre-set Zwift workout, riding on Elite Direto trainers.
"From this test protocol, we were able to identify his heart rate response to the heat over time, and obtain measures of his sweat rate, and percentage weight loss due to dehydration, along with his perceptual tolerance to the heat" explained Nichols.
"Using this data we were able to make individualised recommendations to counteract in race dehydration and optimise his post-race re-hydration strategy."
King was able to accelerate away from the one rider still with him under the Flamme Rouge, with plenty of time to raise his hands in the air and celebrate.
“I was really fired up during the final," he commented after his win. "I could feel cramps coming on, and with all the liquid you have to drink throughout the stage, my stomach was a mess but I knew I still had it in me for one last big effort to the finish line.
"I have been working really hard at home in Lucca, where it’s been really hot all July, so I have confidence in my preparation for the Vuelta and today it showed.”
Cycling Weekly's Tech Editor Michelle Arthurs-Brennan is a traditional journalist by trade, having begun her career working for a local newspaper before spending a few years at Evans Cycles, then combining the two with a career in cycling journalism.
When not typing or testing, Michelle is a road racer who also enjoys track riding and the occasional time trial, though dabbles in off-road riding too (either on a mountain bike, or a 'gravel bike'). She is passionate about supporting grassroots women's racing and founded the women's road race team 1904rt.
Favourite bikes include a custom carbon Werking road bike as well as the Specialized Tarmac SL6.