Effects of cryotherapy on arthrogenic muscle inhibition using an experimental model of knee swelling.
OBJECTIVE
Arthrogenic muscle inhibition (AMI) contributes to quadriceps weakness and atrophy in knee arthritis and following joint injury. This laboratory-based study examined the efficacy of cryotherapy in reducing quadriceps AMI caused by intraarticular swelling.


METHODS
Sixteen subjects without knee pathology participated, and were randomly assigned to a cryotherapy (n = 8) or control (n = 8) group. Surface electromyography (EMG) from vastus medialis and quadriceps torque measurements were recorded during maximum effort isometric contractions. All subjects then received an experimental joint infusion, whereby dextrose saline was injected into the knee to an intraarticular pressure of 50 mm Hg. EMG and torque measurements were repeated. Thereafter, the cryotherapy group had ice applied to the knee for 20 minutes while the control group did not receive an intervention. EMG and torque measurements were again collected. Quadriceps peak torque, muscle fiber conduction velocity (MFCV), and the root mean square (RMS) of EMG signals from vastus medialis were analyzed.


RESULTS
Quadriceps peak torque, MFCV, and RMS decreased significantly following joint infusion (P < or = 0.001). Cryotherapy led to a significant increase in quadriceps torque and MFCV compared with controls (P < 0.05). The difference in RMS did not reach statistical significance (P = 0.13).


CONCLUSIONS
The study demonstrated that cryotherapy is effective in reducing AMI induced by swelling. Cryotherapy may allow earlier and more effective quadriceps strengthening to occur in patients with knee joint pathology.
Rice
David
D
AUT University, Auckland, New Zealand. david.rice@aut.ac.nz
McNair
Peter J
PJ
Dalbeth
Nicola
N
D000328:Adult; D017679:Cryotherapy / Q000379:methods*; D004576:Electromyography; D005260:Female; D006801:Humans; D007270:Injections, Intra-Articular; D007718:Knee Injuries / Q000139:chemically induced / Q000503:physiopathology* / Q000628:therapy*; D007719:Knee Joint / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D009119:Muscle Contraction / Q000502:physiology; D018908:Muscle Weakness / Q000503:physiopathology / Q000628:therapy; D009431:Neural Conduction / Q000502:physiology; D052097:Quadriceps Muscle / Q000294:innervation / Q000503:physiopathology*; D012965:Sodium Chloride / Q000008:administration & dosage / Q000009:adverse effects; D019415:Torque
D012965:Sodium Chloride