The manual handling regulations are not a "one size fits all" law. There are plenty of variations between human beings and the slide shown here indicates most, but not all, of them. I know it's unfashionable to say these thing nowadays but there is no way a petite lady can life the same weight as a burly male wrestler!
Ladies who are pregnant should try to avoid heavy manual handling operations and should, ideally, avoid them completely during the last three months of confinement,
Age is an important factor too. Young people may have not have maximum muscle development and conversely, although older workers may have the experience that may have less strength due to the aging process
Body build is an important factor too. Someone who works out at the gym regularly is probably better placed to do heavy manual handling tasks that a person who leads a sedentary lifestyle.
Physical fitness also comes into this category. If someone is ill or maybe has an injury, their manual handling duties should be adjusted accordingly.
Whilst not everyone requires an in depth manual handling training course it is important that people are given the knowledge to carry out the tasks expected of them.
If someone is fatigued they are unlikely to be able to complete their manual handling tasks as efficiently or safely as usual.
Similarly if someone is ill or has recently been ill, it may affect their ability to carry out their usual manual handling tasks.