Long distance runners know loneliness. Fallen footballers know fakery. Fast bowlers know pain.
It's part of what they bring to every net session and match. Like sunblock, a stud spanner and a pair of cycle shorts.
At best it's only pain - a thud or stab somewhere in their bodies sometime during their run-up, delivery or follow through. Or all the time.
When the day or the day/night is done bowlers pack up their pain, take it with them and bring it back next time. Every time.
Blood in the boots is the cliché. And like all clichés, it's true.
But what happens when the blood escapes the boots? When Dale Steyn breaks a shoulder? Or Vernon Philander is felled by a back injury? And Chris Morris? Or Morne Morkel rips his side?
Or all of the above, as has befallen South Africa in less than a year?
"It's been a major cause of concern for us," sports medicine specialist Shuaib Manjra said this week.
The buck stops with Manjra, the chairman of Cricket South Africa's medical committee.
"We've had a long discussion over it in the last week or two, among all the role players. We are putting a plan together to begin to understand what's causing it and what we can do about it."Manjra listed bowlers' workload, faulty actions, the state of their conditioning, and the effect of the "sudden acceleration in the number of overs they bowl per week" as the visible tips of the injury iceberg.
Faf du Plessis looked beyond science to try and explain the calamity.
"Age is a factor," Du Plessis said. "Dale, Morne, Vern are all getting to that stage where your body has a few more niggles. Then you need to work harder."
Steyn is 34, Morkel 33, and Philander is 32. They are all staring into the sunset of their careers.
But there is hope for the ballies, Du Plessis said. "Morne is a great example. He had a really bad back injury and the work he did behind the scenes for a year was a great example for the young guys. He came back and he was at his best ever.
"As a batsman I don't rock up and just run around anymore. I need about a 40-minute stretch just to get going. That's part of getting older.
"When you've bowled all those overs in your career it will catch up to you."
Except that Morkel put in the effort and was still crocked. Perhaps he didn't see it coming.
"At any point in time these guys are carrying a niggle, and they go into the game with that niggle," Manjra said.
"If we're going to withdraw every player because they've got a niggle we're not going to have a team. But you need a clear and sustained period where they can rest and strengthen themselves to be able to go back and play.
"The IPL [Indian Premier League] and all that is getting in the way, and that means the load on the players is enormous and we can't find that sustained period of rest and rehabilitation."And while there's logic in making the most out of what veteran bowlers have left in the tank there's also danger.
"We're concerned about how we preserve our older bowlers without punishing our younger bowlers," Manjra said. "People like Kagiso Rabada or Andile Phehlukwayo, I'm really concerned about overloading those players."
So Manjra and his colleagues keep a close watch on how many overs bowlers send down and flag those needing a rest.
He concedes that his charges are monitored less when they play outside the franchise or national structures.
Another worrisome tendency is players eschewing official fitness trainers and physiotherapists.
"Some of the problem occurs when guys go outside of that system and have personal trainers elsewhere," Manjra said.
"Then they end up doing stuff we've got no control over."
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