People in their 90s are not meant to attack competitive sport with the same vigour as a 20-year-old.
Jacob (95) defies common logic and is working and training harder than when she started masters sport four years ago.
She is not complacent and has added more work in the gymnasium to her training programme over the past 12 months.
She now spends four days in the gymnasium and has a 5km walk each Wednesday.
Jacob is never satisfied and was unhappy with her winning time of 39.3sec for the 100m sprint in athletics on Saturday.
"That's not good," she said.
"Last time in Dunedin I did it in 38 seconds and that was in 30degC heat and with a head wind."
She shifted to the indoor rowing venue in the Marquee at the Games headquarters yesterday and won four more gold medals in the 300m (1min 45.8sec), 500m (3min 10.7sec), 1000m (6min 41.5sec) and 2000m (13min 31.40sec).
New Zealand records were set in all but the 300m.
The 1000m was a world record for the over-90 age group.
Jacob set a world record for the 300m in 2008.
"I was a bit surprised at the records," Jacob said.
"It was not any harder than at other times."
Jacob has already won five gold medals at the Masters Games and 20 in her career that began in 2006.
She will add another gold medal in the 5km walk on Wednesday night.
What is her secret?"Do daily exercises, eat properly and get enough sleep," Jacob said.
"Indoor rowing is a great way to exercise without pain."
Jacob began competing at the Masters Game when she was 91.
Joint problems in her hands meant she could no longer continue as a dressmaker or play the piano, and she wanted something to do.
Ron Riley (Southland) broke lightweight New Zealand records in the aged 70 to 74 1000m (3min 38.30sec) and 2000m (7min 36.20sec).
He reduced the 2000m record by 16.50sec.
Gordon Fletcher (Auckland) broke the heavyweight record in the aged 70 to 74 grade in the 500m (1min 36.10sec) and 300m (53.70sec).
Other New Zealand records went to Linda Liddy (US) in the women's aged 50 to 54 1000m (3min 45.10sec), John Hunter (Christchurch) in the men's aged 65 to 69 1000m (3min 26.6sec), Steve Geary (Invercargill) in the men's aged 50 to 54 300m (50.50sec), Jocelyn Dobson (Riverton) in women's aged 55 to 59 2000m (7min 51.7sec) and Marinus Boon (Dunedin) in the mens aged 80 to 84 300m (55sec).
