Reduced Appendicular Lean Body Mass, Muscle Strength, and Size of Type II Muscle Fibers in Patients with Spondyloarthritis versus Healthy Controls: A Cross-Sectional Study

Table 2

Quadriceps femoris: parameters of volume, CSA, and muscle function.

Variable	Patients	Controls	(95% CI lower; upper)
QF total volume, cm^3	2013 ± 382 (1457–2738)	2296 ± 293 (1836–2705)	0.004 (−447.5; −118.4)
QF mean CSA, cm^2	60 ± 9 (46–75)	63 ± 7 (52–72)	0.17 (−8.7; 1.8)
QF max CSA, cm^2	81 ± 11 (65–97)	86 ± 9 (73–104)	0.07 (−12.3; 0.5)
Specific strength
MVC Nm/QF total vol., Nm/cm^3	0.094 ± 0.01 (0.08–0.11)	0.099 ± 0.01 (0.09–0.11)	0.36 (−0.017; 0.007)
MVC Nm/QF max CSA, Nm/cm^2	2.32 ± 0.37 (1.87–2.93)	2.62 ± 0.22 (2.30–2.96)	0.08 (−0.64; 0.05)
Peak RFD, Nm/s	1639 ± 319 (1383–2425)	1950 ± 841 (1115–3913)	0.44
Muscle endurance
Number of repetitions	38.3 ± 13.8 (19–56)	38.6 ± 8.2 (30–54)	0.95 (−13.6; 12.8)
Total workload (reps × kg), kg	568.5 ± 206.3 (267.8–857.2)	690.5 ± 151.4 (503.1–988)	0.10 (−270.4; 26.5)

Values are mean ± SD (range) unless otherwise indicated. Comparison between groups tested by paired samples -test unless otherwise indicated. Log-transformed variable. Wilcoxon signed ranks test. CSA: cross-sectional area. MVC: maximal voluntary contraction. Nm: Newton meter. QF: m. quadriceps femoris. RFD: rate of force development.