Underhill, who underwent ankle surgery six weeks ago, will return to the field in six weeks provided his rehabilitation continues at the rate it has.
The Bath flanker has already suffered several concussions, with some suggesting his all-action style has left him vulnerable to head knocks.
“It’s probably something I’ve tried to stop [playing physically],” Underhill told Vernon Kay at a live pre-game event in Twickenham. “A disregard for your own body is great when you’re young, and you feel really good, and then you play a couple of seasons and you think ‘I’m not sure I can keep this up’.
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“People kind of expect you to be like that all the time, and when you can’t it’s tough to keep up. I’ve tried looking after myself a little more and my tackle technique, I’ve tried not to put my head in the wrong place.
“Safety is pretty key when you are teaching young people to play. You don’t want them smashing into each other. It’s great to watch when they’re adults, but you don’t want people getting hurt.
“Technique is so important for a long career… especially in the tackle area, making sure you’re not injurying yourself unnessarily, and other people around you.”
Former England backrow Neil Back told RugbyPass last year that he believed Underhill needed to look at his tackling technique.
“Of course he’s got to concentrate on the perfecting his tackle technique but he has to get smarter too. You see him looking to make big hits, but that can take you off your feet,” Back told RugbyPass.
“If you’re off your feet you’re out of the game. Intelligence in the tackle area is vital – getting over the ball quickly. You need to stay in motion and stay in the game.”
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