During the first four days of competition there have been swathes of red on the scoreboards showing more no-lifts than good lifts.

In the six A Groups so far, 50.7 per cent of all attempts have been no-lifts.

At the last comparable IWF World Championships in 2018, when it was also an Olympic qualifying event with top-quality entries, the ratio of no-lifts in the same six A Groups was far lower at 39 per cent.

In the men’s 61kg, there were 36 no-lifts from 60 attempts, eight of them by two men who said the altitude had adversely affected their performance.

Eko Yuli Irawan of Indonesia, the Olympic silver medallist who was again beaten by China’s Li Fabin, said he had struggled in the conditions.

Sergio Massida from Italy finished fourth despite, like Irawan, making only two good lifts.

The 2021 junior world champion Massida said: "The altitude has made a difference, it’s harder in training, warm-up, competition.

"I still feel strong, but it’s the breathing…"

Irawan’s team-mate Rahmat Erwin made a world record clean and jerk of 200kg in the men’s 73kg B Group today but he, too, felt the effects.

He looked totally drained and barely able to stand up after his record-making lift and was flat out on the floor of the warm-up room for several minutes afterwards.

"It’s my breathing," he said.

"I’ve been OK in training but this time it’s really hard."

Another Italian who looked to be struggling was Lucrezia Magistris, who failed to make a total in the women’s 59kg yesterday when the winner was Yenny Alvarez, who lives in Colombia.

Does the home nation have an advantage?

"I don’t think so, because many of our weightlifters live and train at sea level in Barranquilla," said William Peña, President of the Colombian Weightlifting Federation.

Dr Mike Irani, who was Interim President of the IWF until the elections in June this year and who has been duty doctor at several sessions said: "The altitude is definitely a talking point."

Athletes are having problems with oxygen intake which, Irani said, becomes worse when they tighten their belts.

"Some of the athletes are not getting enough oxygen," he said.

"If you haven’t got oxygen going to your brain you’re not going to function properly."

On one occasion he advised a coach not to send out his athlete for a third attempt but "he overrode my advice… there’s nothing in the rules to cover it."

The effects of altitude, in simple terms, cause "a decline in aerobic performance" according to the Journal of Sports Medicine.

The Tunisian chair of the IWF Medical Committee, Fathi Masmoudi, said one of the Tunisian athletes was having problems in training.

"I think if athletes have had to cut weight and then compete at high altitude they have found it very difficult," he said.

Others have pointed out that a number of athletes put in very high entry totals to get into the A Groups, and have had to overexert when they get there.

Given that there have been more red lights in A Groups than other sessions, this could be a factor.

The United States team had a training camp at altitude in preparation for the World Championships.

Ursula Papandrea, the American who is first vice-president of the IWF and has an academic background in exercise science, explained why some athletes are having difficulties.

"Thin air (at high altitudes) has inherently less oxygen, which means each breath will deliver less oxygen to your muscles, which then affects ATP (adenosine triphosphate) generation needs for muscle contractions," she said.

"Scientifically, we know the physiological effects of altitude and when coupled with the valsalva manoeuvre (breathing technique) used in lifting, it’s a particularly difficult position for the athlete.

"The record number of missed lifts trending across all classes is the consequence.

"These are professionals who have trained rigorously for this day.

"No one should make them feel like they are creating an excuse - it’s simply scientific.

"We should provide the best performance conditions possible.

"The interesting thing is that athletes may not feel short of breath but this doesn’t change the fact that the muscles are less oxygenated, in which case they may not even realise that they are being affected."