The plague of the back injury stalls Cummins, de Lange

When the series between South Africa and Australia drew to an abrupt close last summer - they played just two Test matches instead of the originally planned three - the consolation was that two fast-bowling seedlings had been planted. And the hope was they would have grown into something resembling flowering trees by the next time the two sides met.

That time has come and neither Marchant de Lange nor Pat Cummins will participate in a series that has been dubbed the battle of the pacers. De Lange, who came to prominence with his five-wicket haul for South Africa A against Australia last year, has not played cricket since June. His last first-class match was a Test in Wellington in March. Cummins was in action a little over a week ago for Sydney Sixers in the Champions League T20 but has now been ruled out of the rest of the summer. The last red-ball game - and the only Test - he played in was the Wanderers Test in November 2011.

Both have stress fractures of the lower back, although Cummins has also had one in his foot, and both have had their recovery period lengthened and their return delayed.

De Lange was due to play in South Africa's domestic one-day competition that started on Friday, but is still not fully fit. His return has been put back to early next year, which means he will probably miss out on the home series' against New Zealand and Pakistan. Cummins is targeting next year's Ashes for his return but nothing can be certain, especially because stress fractures are such nasty injuries with such lingering tendencies that so few really understand.

"The best way to explain it would be to say it is a bony reaction," Mohammed Moosajee, South African team manager who is also a medical doctor, told ESPNcricnfo. "The spine is made up of vertebrae and the muscles that join each vertebrae act as stabilisers for the spine. When those muscles are affected and can no longer perform their function properly, it affects the bone, which has to carry a greater load. It is not a complete break but if it is left untreated it could turn into a complete break."

Bowlers are particularly at risk of straining the muscles in their back because of the task they perform. "The physical act of bowling causes this. There is hypertension when they arch the back, the rotation of the side and flexing. Even when you land, you put a force of 10 times your body weight onto your foot," Moosajee explained.

Those who are under-23 are even more prone to the condition. "Young people have a growth spurt, which only ends around that age," Moosajee said. "Before that, their bodies are still developing." Cummins is only 19, de Lange 21 and both have had more injuries than the likes of Dale Steyn or Morne Morkel, who debuted much later and played much less cricket.

It may sound like nothing more than a curmudgeons' curse to blame 20-overs cricket for the overload but to some degree it is responsible. Even though bowlers are only allowed four overs in the match, it's the work they do before hand in the nets that adds to their delivery count. De Lange was part of the Kolkata Knight Riders squad and bowled extensively there, then he went to Zimbabwe on an unofficial 20-overs tournament and got injured. To say it was simply coincidence is wishful. "Things like being in training every day, day in, day out, has an impact," Moosajee said.

Even just those four match-time overs can take their toll. Because it's just 24 deliveries, bowlers will throw all their efforts into it and the exertion could result in injury. "It's short, sharp bursts and could be too much all at once," Moosajee said.

"I spoke to Pat for about an hour on the phone the other night and told him that I have been through the same thing ... Pat's body is maybe not mature enough for what he is doing. It's disappointing for Pat, at his age you don't look to the future, you want everything there and then."Australia fast bowler James Pattinson

Twenty-overs cricket is not the only format that is played more frequently and the amount, overall, is a concern. Something as simple as switching between formats has caused Cummins to wonder whether that has hurt his back. While he strives for correctness with the red ball, he looks for variation with the white and the slight changes in action could be doing him in harm.

It could mean that cricketers have to be more selective about how much they play and what they format they choose to play in. James Pattinson, another Australia quick, is an example. Pattinson suffered two stress fractures at the ages of 16 and 18 and was suspected of having a third during the tour of the West Indies. He has since chosen to focus on the longer game, evident in that he has only played one List A game so far this summer, and had had a word with Cummins about the issue.

"I spoke to Pat for about an hour on the phone the other night and told him that I have been through the same thing," Pattinson said. "I said to him that if you bowl at 150 [kph] you are bound to get some injuries. Look at someone like Glenn McGrath, he made his debut at 23 and those years make a big difference. Pat's body is maybe not mature enough for what he is doing. It's disappointing for Pat, at his age you don't look to the future, you want everything there and then."

Pattinson has empathy for his situation. He said he understands that It is difficult trying to cherry pick when you are young, enthusiastic and want to be involved everywhere you can. "It's tough mentally and physically to play in all formats but even I want to play in all three. It's tough to try and work it out but you have to."

For Moosajee too, the management of young bowlers is becoming increasingly important, because there is only so much the medical staff can do. Stress fractures can be tricky to diagnose and only when that has been achieved properly can the rehabilitation process start. Some bowlers go weeks without knowing exactly what the problem is.

"At first you feel discomfort and bowlers sometimes want to and can bowl through that," Moosajee said. "It's not always pain. Pain is something that restricts you, discomfort you can live with." Moosajee said it's up to team management to act quickly as soon as they suspect something is wrong. "When bowlers feel discomfort we immediately do investigations and usually an MRI will detect a stress fracture. As soon as that happens, the bowler will need a back brace. After that, rehabilitation starts with work on the core to strengthen the muscles there. Even after all of that, the injury could recur."

That has already happened with both de Lange and Cummins and the cricketing world can only wait in uncertainty for the exciting pair's return. Cummins' won't be for at least six months but de Lange's could be sooner, although it is likely to be limited to domestic matches because of the schedule - South Africa only play Test cricket again in October next year but the IPL along with a few other 20-overs leagues, the Champions Trophy and a limited-overs tour of Sri Lanka will all take place before that.

If the management chooses the smart route, they will not rush him back for any of that but save him for later so he can fulfil the promise he showed 12 months ago.