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THE shortest rope is a concept that is involved when stretching a functional group of muscles. Stretching is essentially a mechanical process that involves lengthening soft tissue, more specifically muscular/myofascial tissue. And a functional group of muscles is a group of muscles that all share the same mover action—in other words, the same function. The psoas major is part of the functional group of hip flexors (Image 2). So, given that the psoas major is a flexor of the thigh at the hip joint, shouldn't bringing the client's thigh into extension stretch it? Not necessarily. The reason this position might not succeed in stretching the psoas major is that the psoas major is not the only member of the functional group of hip flexors. It is only one of 12 muscles that cross the hip joint anteriorly—from the anterior fibers of the gluteus minimus and medius laterally to the adductor magnus medially (See Hip Flexor Group box, page 77). So even though the position shown in Image 1 will place a stretch force on the hip flexor group and, therefore, theoretically stretch every one of the hip flexors (including the psoas major), in reality, it will not stretch every one of the muscles of this group and, therefore, may not stretch the psoas major. Instead, it will stretch only one muscle of the functional group. Which one? Whichever hip flexor is the shortest/tightest one of the group. This shortest/tightest muscle will stop the stretch force, preventing it from stretching the other members of the group. This muscle can be called the shortest rope. The shortest rope analogy can be best understood by picturing a person holding five ropes: one of the ropes is 1 foot long, another is 2 feet long, another is 3 feet long, another 4 feet long, and the last one is 5 feet long. All five of the ropes are being held by their ends and the ropes are hanging slack (Image 3A). In this analogy, the five ropes represent five muscles of a functional group, and the ends of the ropes represent the muscles' attachments. When the person starts to pull the ends of the ropes away The functional group of hip flexors. Image from Joe Muscolino's The Muscular System Manual, The Skeletal Muscles of the Human Body, 4th ed. ( Elsevier, 2016). WKULE 6DUWRULXV ,QJXLQDOOLJDPHQW ,OLRSVRDVGLVWDO EHOO\WHQGRQ *UHDWHUWURFKDQWHU RIIHPXU 3HFWLQHXV +HDGRIILEXOD )HPRUDOQHUYHDUWHU\ DQGYHLQ 9DVWXVODWHUDOLV ,OLRWLELDOEDQG ,7% 9DVWXVPHGLDOLV 6HPLWHQGLQRVXV 3VRDVPLQRU 3VRDVPDMRU ,OLDFXV 3LULIRUPLV *OXWHXVPLQLPXV 3LULIRUPLV $GGXFWRUORQJXV *UDFLOLV $GGXFWRUPDJQXV 7LELDOLVDQWHULRU ([WHQVRUGLJLWRUXPORQJXV )LEXODULVORQJXV *DVWURFQHPLXV 6ROHXV *UDFLOLV 6DUWRULXV 3HVDQVHULQH WHQGRQ $ 7LELDO WXEHURVLW\ 3DWHOOD 5HFWXVIHPRULV 4XDGULFHSV IHPRULV 7HQVRUIDVFLDH ODWDH7)/ *OXWHXVPHGLXV $EGRPLQDODRUWD ,QIHULRUYHQDFDYD *OXWHXVPHGLXV 2 74 m a s s a g e & b o d y w o r k j u l y / a u g u s t 2 0 1 7