As Martin Johnson and his coaching staff continue to rack their brains for the reasons behind England's chastening defeats over the past few weeks, there may be a refreshingly straightforward answer at hand: their players are simply not fit enough.

Heyneke Meyer, the South African head coach of Leicester, believes that the most striking aspect of the dominance of southern-hemisphere teams in the past month has been their superior fitness levels.

Hence the ability of New Zealand and South Africa to score three tries each in the final half-hour of their games at Twickenham, some of which could be ascribed to England chasing the game, but Meyer believes that the burning lungs among England players were also a telling factor. “I truly believe the one thing that needs to pick up in the northern hemisphere is the fitness levels,” Meyer said yesterday. “In the southern hemisphere, there is much more emphasis on a high-intensity game and therefore on fitness. If you look at the Test matches, England were there until the last 20 minutes, but that's when the guys get tired.”

Before anyone at the RFU gets too excited and thinks that England need only to lift a few more weights, Meyer gives warning that the problem is endemic. Its causes, he believes, are rooted in the style of rugby played in Europe and in the structure of the season. These are problems that are not so easily solved.

Meyer is well qualified to pass judgment. Having led the Bulls to the Super 14 title in 2007, he was expected to succeed Jake White as coach of South Africa, only to lose out to Peter de Villiers. He has found in the Guinness Premiership a culture that often prizes attrition above artistry.

“In the northern hemisphere, it's more of a physical game, stop-start with the emphasis on scrums and collisions, while in the southern hemisphere it's different, it's more of an open, running game,” Meyer said. “I'm used to [seeing teams] building eight or nine phases, so if the [English] guys aren't used to it, they will get tired. I could see from England's bodies in the last 20 minutes that it was tough on them.”

The real opportunity for players to build up their basic fitness levels comes in the off season and, in that respect, perhaps players in the northern hemisphere are fighting an uneven battle. While the Super 14 runs from mid-February to the end of May, with the Tri-Nations internationals in July, August and September, the European season stretches to a gruelling nine months from September to late May.

“I was only here for the last two weeks [of the summer] and people said it was the toughest training they'd ever had in the off season,” Meyer said. “Imagine if I had them for eight weeks. Then they could be super-fit, they wouldn't get so many injuries and they could maintain that fitness throughout the season. But because the season here is so long, the players don't really have an off season.”

As the Heineken Cup resumes this weekend, boosted by a new four-year deal for the title sponsor, Meyer is battling an injury crisis before the back-to-back ties against Perpignan, starting at Welford Road on Saturday. The casualty list in English rugby, he believes, is unlikely to be trimmed unless a lead on players' fitness is given by Rob Andrew, the RFU director of elite rugby, and Johnson, the England team manager. “It should come from the national level downwards,” Meyer said. “The national team really needs to sit down and see how we can improve fitness levels in this country.”