Affordable Access

Publisher Website

Specific force of the vastus lateralis in adults with Achondroplasia.

  • Sims, David Thomas1
  • Onambele-Pearson, Gladys L1
  • Burden, Adrian2
  • Payton, Carl1
  • Morse, Christopher I1
  • 1 1 Manchester Metropolitan University.
  • 2 2 Manchester Metroploitan University, UK.
Published Article
Journal of Applied Physiology
American Physiological Society
Publication Date
Nov 16, 2017
DOI: 10.1152/japplphysiol.00638.2017
PMID: 29146686


Achondroplasia is a clinical condition defined by shorter stature and disproportionate limb length. Force production in able-bodied individuals (controls) is proportional to muscle size, but given the disproportionate nature of Achondroplasia, normalising to anatomical cross sectional area (ACSA) is inappropriate. The aim of this study was to assess specific force of the vastus lateralis (VL) in 10 adults with Achondroplasia (22 ±3 yrs) and 18 gender matched controls (22 ±2 yrs). Isometric torque (iMVCτ) of the dominant knee extensors (KE) and in vivo measures of VL muscle architecture, volume, activation and patella tendon moment arm were used to calculate VL physiological CSA (PCSA), fascicle force and specific force in both groups. Achondroplasia muscle volume was 53% smaller than controls (284 ±36 vs 604 ±102 cm3, P < 0.001). KE iMVCτ was 63% lower in Achondroplasia compared to controls (95 ±24 vs 256 ±47 N∙m, P < 0.001). Activation and moment arm length were similar between groups (P > 0.05), but coactivation of Achondroplasia bicep femoris was 70% more than controls (43 ±20 vs 13 ±5%, P < 0.001). Achondroplasia had 58% less PCSA (43 ±10 vs 74.7 ±14 cm2, P < 0.001), 29% lower fascicle force (702 ±235 vs 1704 ±303 N, P < 0.001) and 29% lower specific force than controls (17 ±6 vs 24 ±6 N∙cm-2, P = 0.012). The smaller VL specific force in Achondroplasia may be attributed to infiltration of fat and connective tissue, rather than to any difference in myofilament function.

Report this publication


Seen <100 times