Rising middle-distance sensation Cameron Myers has helped Australia to a record haul of 14 medals at the world junior athletics championships in Peru.

Myers, 18, pocketed a bittersweet silver in the men's 1500m as the green and gold squad claimed four medals on the final day of the championships.

Izobelle Louison-Roe was second in the women's long jump, while the women's and men's 4x400m teams claimed silver and bronze respectively.

Myers (three minutes 40.60 seconds) led into the home straight on Saturday (Sunday AEST) but was just pipped for gold in a tactical 1500m final by Ethiopia's Fayisa Abdisa in 3:40.51.

"It's bittersweet when you follow your race plan, do everything right and someone is just better than you. That's the reality of this sport sometimes. It's motivating and I'll be back stronger," Myers said."What's a professional runner that doesn't want to win medals?

"It's a great step in the right direction and no doubt it's going to give me that kick-start into next year."

Last year, Myers became the second-youngest man to break the four-minute barrier for the mile.

Louison-Roe produced a personal-best clearance of 1.89m to claim an impressive silver in the high jump behind Serbia's Angelina Topic (1.91m).

The 17-year-old Australian will still be eligible for the 2026 world juniors in Eugene, Oregon.

"I knew coming in that the competition was really hard because they are all fantastic jumpers. I knew I would have to post a PB to get anywhere, I'm just so excited," she said.

"I'm coached by my Mum (Karen). We're on the same page and it's one of those things that you honestly couldn't buy."Australia completed a unique triple by winning medals in all three 4x400m relays, having claimed gold in the mixed race on the opening day of competition.

The final medals tally of 14 was four better than the previous high-water mark set in 1996, providing a further boost for the sport in Australia after the impressive seven-medal haul at the Paris Olympics.