Why are we so obsessed with posture and its correction? There is a notion in the health and wellness industry that "bad" posture causes or will cause pain. Stemming from Kinesiology (studies of human movement) and body mechanics, there are plenty of assumptions about muscular imbalances linked to imperfect posture, but what is a perfect one and can it actually be held all day long?
Studies show, there isn't a clear cause and effect relationship, e.g. does bad posture lead to muscle imbalance (some muscles being short and tight/others long and weak), or does muscle imbalance leads to poor posture. The idea is that those muscle imbalances lead to dysfunction, which leads to wear and tear, which leads to injury and pain. Although, fairly intuitive and easy to imagine, there is no scientific evidence that above is true. There is some correlation between posture and pain, but again it is hard to definitively ascertain if the pain is a result of posture or posture is a result of pain. Funnily enough, people with back pain maintain "better" posture than people with no back pain (who don't have to adjust anything to stay pain free).
Posture is a thing and we all have one and we can all modify it. It changes based on our mood, time of the day, level of fatigue, but it doesn't affect our physical well being as much as we are meant to believe. It also changes throughout stage of life. As we get older, our posture changes. Note, there aren't many 80 year old ladies sticking their bottoms up - the usual sign of anterior pelvic tilt which creates deep arch in the lower back).
"Perfect" posture is very much an aesthetic construct historically linked to class culture. Don't think that farmers in 1900s' were tutored to keep their heads high and shoulders down to avoid pain after a whole day in the fields.
In Pilates we teach neutral pelvis and neutral spine concepts, which today most agree is an arbitrary alignment of the pelvis so your hip bones and pubic bone are roughly in the same plane. It then helps with alignment of your spine to bring back the natural and not exaggerated curves in your spine. But here comes a surprise...human beings are full of asymmetry and imbalances (from internal organs, to shorter/longer limbs and pretty much everyone has one shoulder higher than the other).
So can we "improve" our postures and how much work does it take? It is a tricky one. I believe that by strengthening the core and back, we can make it more effortless to hold our "better" posture for longer, but we still have to consciously remind ourselves to switch it on. For me, that means dropping my tailbone, and getting my deep abs gently engaged to bring the ribcage over pelvis, shoulders away from the ears and slightly rotating outwards. But can I hold it all day long? NO! Would I want to? Probably not. Your tummy has to be relaxed for a full belly, relaxed breathing which is so beneficial to us.
Is 1 hour of Pilates a week enough to achieve that? Honestly? Probably not but any regular resistance training few times a week that strengthens core and upper back, combined with the increased body awareness you gain from Pilates practice can definitely make it easier to switch on your "better" posture more often. And because the muscles are stronger, you don't fatigue so easily and are able to incorporate it more into your day to day activities and performed sports.
Also, what is important is to not stay in the "bad" posture for extended periods of time, so it is really important to keep moving. Your best posture is your next posture. If you are sitting slouched in front of the screen, take regular breaks to stretch, walk around, create some shapes with your body which are opposite to the posture you have held.
Movement is what humans need for optimal performance, but that's a topic for another post:)