The 28-year-old Tintu, mentored by Usha, has enjoyed success at the Continental level, winning a bronze and a silver at the Asian Games - 2010 Guangzhou (2:01.36) and 2014 Incheon (1:59.19) apart from six medals at the Asian Championships.
However at the World Championships, where the best in the business compete, she has struggled to make an impression in her three attempts so far.
She finished 15th in Daegu (South Korea, 2011) only to be eliminated in the 800m semi-finals and 19th in Beijing (2015), where she could not proceed beyond the Heats.
In the 2013 World Championship in Moscow, Tintu only competed in 4X400m relay and was part of the team that finished a lowly 15th.
Usha, who is country's greatest ever female sprinter till date, has been training her from the beginning. The 'Payyoli Express' says she won't take criticism for Tintu's average success at the global meets and strongly objected to the suggestions that a foreign coach can help her ward improve.
"For me it's not a problem but show me one foreign coach who has come here, trained Indian athletes and has got the medals (World Championship and Olympics)," Usha counter- questioned.
"Since the year 2000, foreign coaches are training Indian athletes, are there any Olympic medals? Are you saying that only if Tintu trains with a foreign coach, she will get a medal," an angry Usha retorted during an interview with PTI.
"It is up to Tintu, not me (to decide on her future).
Tintu is senior Asiad medallist, Jessy Joseph is junior Asian Championship gold medallist, Jisna Matthew (Indian relay team member) is also there. Lot of others are coming up," she said, defending her training methods.
Usha, who missed an Olympic bronze by 0.01 seconds at 1984 Los Angeles Games, also explained how she has been trying different strategies to help Tintu improve.
"We are trying different methods with her but it is not suiting Tintu. 800 metres is not same for all. Tintu runs with the speed. Running with the speed means, take 400m time, 600m time and 1000m time and then you take percentage and make a lap. And run one more lap and it will be may be 3, 3.5 seconds above the second lap, it is like that.
"The other one is run a slow lap and maybe the same second lap. The second one may be 1 second lower than the first. But this is a very rare case in the world, it is a very rare case. It is not possible for everybody. Tintu was trying both the but it was not suiting," Usha explained.
A major criticism that comes Tintu's way is that she sets the pace of the race by taking initial lead but is not able maintain the momentum and intensity in the final 200m.
"Whether you are running in the front or at the back the time will be there. She tried 60 seconds (for first lap) in China (during the Asian Grand Prix). If she goes for 60-61 seconds, it is not possible for Tintu to pick up (for concluding part of race).
"If she goes for 60 seconds in the first lap, upto 600m she will get slower and timing will go upto 1 min 30 seconds.
If she goes upto 1 minute 31 secodns, it will go above 2 minute 03 second, no doubt. If she runs sub 1:30 min (till 600m), she will then come under 2:02 min undoubtedly and if she is under 1:20, she will clock a sub-two minute timing," she further explained the issue.
Usha said the way Tintu starts the race is actually the best option for her and they will continue with the same strategy for the upcoming World Championship in London.