The principles of structural integration (Rolfing) and the application of Tom Myer’s Anatomy Trains fascial lines schema through Kinesis Myofascial Integration are used by all kinds of modalities, with great enthusiasm.
The suggestion of whole-body fascial and myofascial linkages is that because connective tissue spans multiple structures (in this case muscles), one must influence the other and visa versa i.e. if one muscle is “tight” (a BS term), the other must therefore also have increased tone (be tight), and by extrapolation, manual ‘treatment’ applied to one structure must affect everything else in the line.
The system gives rise to all sorts of wildly stupid suggestions like this one “Are Your Weak Neck Muscles Making Your Hamstrings Tight?”
and therapists buy into it in their droves!
In the ‘superficial back line’ (SBL) the calves are connected to the hamstring – the line runs from the plantar fascia on the base of the foot to the scalp…
Here’s just one example where it all quickly falls apart.
My wife is a former dancer. She can fold herself in half at the hips and easily put her hands flat on the floor. Her hamstring extensibility is so excessive that her lumbar barely moves into flexion at all. Ever. At her ankles though, years spent dancing on her toes has created functionally short (proponents of anatomy trails would call them “tight) calves. Ankle dorsiflexion is as limited as her lumbar flexion to such an extent that she has early heel-rise in the stance phase of gait and an excessive foot progression angle (toeing out). Her body simply adapted to the activities she was doing at the time…and stayed that way.
Two connected and adjoining muscles in her SBL are at opposing ends of the extensibility (“tight”) spectrum – her hamstrings are extraordinarily long and her calves extraordinarily short.
It’s it pathological? No. Does it need to be treated or corrected? No.
If something is too good to be true, it usually is.