muscle size, patellar tendon CSA, and patellar tendon
moment arm of the WSM were compared with various popu-
lations measured within our laboratory, as indicated in
Table 1,a l o n g s i d ep a r t i c i p a n td e s c r i p t i v e s(10, 11, 13– 15). In
addition, the IMTP and CMJ measures were compared with
existing published literature (included studies are summar-
ized in Supplemental Materials 1 and 2, alongside participant
descriptives).
MRI Measurement of Muscle Tendon Unit Morphology
and Moment Arm
The participant reported for their MRI scan [3.0-T
Discovery MR750W (70-cm-wide bore), GE Medical] having
not completed any strenuous physical activity in/C21 24 h and
had received prior instruction to arrive in a relaxed state hav-
ing eaten and drunk normally. The participant sat quietly for
15 min prior to their scan. The participant lay supine for the
MRI scan of the lower-body musculature from T12 to the lat-
eral malleolus. A body coil (GE Medical) allowed axial T1-
weighted images (time of repetition/time to echo 600/8.144
ms, image matrix 512/C2 512, ﬁeld of view 500/C2 500 mm,
pixel size 0.9766/C2 0.9766 mm, slice thickness 5 mm, and
interslice gap 5 mm) to be acquired in ﬁve overlapping
blocks. Images of both sides of the body were acquired
within a single scan for blocks 1 (T12 to pelvis), 4 (knee joint
space to midshank), and 5 (midshank to lateral malleolus).
However, due to the size of the participant’s thighs, it was
necessary to scan each thigh individually for blocks 2 (pelvis
to midthigh) and 3 (midthigh to knee joint space); this
involved the radiographer repositioning theﬁeld of view
between scanning the ﬁrst and the second thigh but not
physically moving the coil or the participant. Oil-ﬁlled cap-
sules were secured to the surface of the participant’ss k i n
with Transpore tape at intervals along the length of the lower
body prior to the scan and in an ofﬂine analysis used to ver-
ify the alignment of the blocks (Horos software, Version 3.36,
https://horosproject.org/).
The ofﬂine analysis was of the following muscles/com-
partments (Fig. 1): iliopsoas (psoas major and iliacus com-
bined); sartorius; tensor fasciae latae; adductor magnus;
gracilis; gluteus maximus; gluteus medius and minimus
(combined, due to difﬁculty separating the two muscles);
rectus femoris (RF); vastus lateralis (VL), medialis (VM), and
intermedius (VI); semimembranosus (SM); semitendinosus
(ST); biceps femoris long (BFlh) and short heads (BFsh); pop-
liteus; lateral and medial gastrocnemius; soleus; and the an-
terior, lateral, and deep posterior compartments of the
shank. The anterior shank compartment consisted of the
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