Affiliations: [a] Department of Physiotherapy, University of Limerick,
Ireland | [b] Physical Activity, Occupation and Health Research
Unit, University of Limerick, Ireland
Note: [] Address for correspondence: Kieran O'Sullivan, Lecturer in
Physiotherapy, University of Limerick, Limerick, Ireland. Tel.: +353 61 234119;
Fax: +353 61 234251; E-mail: kieran.osullivan@ul.ie
Abstract: Measurement of muscle size is often used to estimate muscle
strength. The validity of these measurements as indicators of muscle strength
is unclear however. This study investigated the relationship of two simple
measures of muscle size (tape and ultrasound) with the concentric isokinetic
quadriceps and hamstrings strength of a group of Irish Gaelic footballers
(n=25). Both tape and ultrasound demonstrated moderate to
excellent reliability at measuring quadriceps and hamstrings muscle size (ICC's
0.69–0.99). Hamstrings were significantly stronger on the dominant limb at
60°/sec (p=0.046) and
180°/sec (p=0.005), but not at
300°/sec (p=0.092). There was no
significant difference in quadriceps strength at any speed (all
p> 0.05). Dominant limbs were significantly larger using the
tape measure (10 cm level: p=0.005, mid-thigh level:
p=0.003). The dominant hamstrings (p<
0.001), but not the dominant quadriceps (p=0.399), were
significantly larger on ultrasound. There were statistically significant
correlations between muscle strength and muscle size measurements, especially
for the tape measurements. However, despite the fact that the dominant limb
muscles were both stronger and larger, the strength of these correlations was
only weak to moderate (r=0.176–0.586). The results
suggest that both tape measurement and ultrasound, while reliable, are of
limited use as indicators of thigh muscle strength.
