B. Andrew Krause

Effect of knee joint effusion on quadriceps and soleus motoneuron pool excitability.

PURPOSE To examine changes in quadriceps and soleus MN pool activity resulting from knee joint effusion over a 4-h period and assess the relationship between the muscles. METHODS A repeated measures before-after trial design was used for this study. Eight, neurologically sound volunteers (age 23.3+/-2.1 yr, height 171.8+/-15.9 cm, mass 65.5+/-17.7 kg) participated in this study. An area superomedial to the patella was cleaned and anesthetized, and 30 mL of sterile saline was injected into the knee joint capsule to mimic mechanical joint effusion. The Hoffman reflex (H-reflex) was elicited by applying a percutaneous stimulus to the appropriate nerve and recording the response through surface electromyography. Soleus and vastus medialis H-reflex measures were collected from each volunteer before, at 30 min, 90 min, 150 min, and 210 min intervals over a 4-h period after knee effusion. RESULTS All soleus H-reflex measures after effusion (30 min 5.89+/-0.92 V; 90 min 6.16+/-0.48 V; 150 min 6.59+/-0.50 V; 210 min 6.70+/-0.56 V) were increased in relation to the preeffusion measure (5.01+/-0.79 V). All vastus medialis H-reflex measures after effusion (30 min 4.23+/-0.94 V; 90 min 4.15 +/-1.11 V; 150 min 4.16+/-0.57 V; and 210 min 4.99+/-1.23) were decreased in relation to the preeffusion measure (5.88+/-1.44 V; P < or = 0.05). CONCLUSIONS Afferent activity from the knee joint capsule resulted in an inhibitory effect on the vastus medialis and a facilitatory effect on the soleus. Facilitation of the soleus in cooperation with other lower extremity musculature could be a mechanism for compensation of the inhibited quadriceps to maintain lower kinetic chain function.

Arthrogenic muscle inhibition is not present in the limb contralateral to a simulated knee joint effusion.

Palmieri RM, Ingersoll CD, Edwards JE, Hoffman MA, Stone MB, Babington JP, Cordova ML, Krause BA: Arthrogenic muscle inhibition is not present in the limb contralateral to a simulated knee joint effusion. Am J Phys Med Rehabil 2003;82:910–916. ObjectiveThe purpose of this investigation was to estimate bilateral neuromuscular activity in the vastus medialis on induction of a unilateral knee joint effusion. DesignEight subjects each were assigned to effusion or control groups. The effusion group had 60 ml of sterile saline injected into their superolateral knee joint capsules. The control group rested for 8 mins. Bilateral recruitment curves for the Hoffmann reflex (H-reflex) and muscle response (M-wave) were obtained before and 10, 20, and 30 mins after the effusion or rest. The maximum H-reflex (Hmax), maximum M-wave (Mmax), and the Hmax/Mmax ratio were utilized for data analysis. ResultsBoth Hmax and Hmax/Mmax ratios decreased from the baseline measure in the effused vastus medialis, whereas no changes were detected on the contralateral side. Effused subjects demonstrated decreased motoneuron pool excitability in the effused limb, whereas control subjects did not differ from baseline. ConclusionsKnee joint effusion results in ipsilateral but not contralateral impairment of quadriceps function. Rehabilitation protocols after knee joint injury should focus on ipsilateral neuromuscular and mechanical alterations that occur as the result of joint damage.

Extracellular calcium chelation and attenuation of calcium entry decrease in vivo cholinergic‐induced eccrine sweating sensitivity in humans

What is the central question of this study? Calcium is an important second messenger in eccrine sweating; however, whether modulation of extracellular Ca2+ and Ca2+ entry has the capacity to modulate sweat rate in non‐glabrous human skin has not been explored. What is the main finding and its importance? Acetylcholine to sweat rate dose–response relationships identify that local in vivo Ca2+ chelation and L‐type Ca2+ channel antagonism have the capacity to attenuate the cholinergic sensitivity of eccrine sweat glands. Importantly, these data translate previous glabrous in vitro animal studies into non‐glabrous in vivo human skin.

Ice Application Effects on Peroneus Longus and Tibialis Anterior Motoneuron Excitability in Subjects with Functional Ankle Instability

ABSTRACT Evidence that focally cooling the ankle joint facilitates soleus and peroneus longus spinal reflex activity in healthy subjects has been reported. This response has been confirmed in individuals with a history of joint pathology for the soleus but not in the peroneus longus and tibialis anterior. The purpose of this study was to identify the effects of ankle cooling on isokinetic eversion and inversion torque and in peroneus longus, tibialis anterior H-reflex (Hmax:Mmax) in subjects with functional ankle instability (FAI). Twenty-four college aged subjects volunteered for this study. Peroneus longus and tibialis anterior Hmax:Mmax, and concentric eversion and inversion torque were recorded prior to and following each session. This protocol was used to compare FAI to healthy ankle group. There were no significant differences between groups. There were weak and no significant relationships between the corresponding muscles motoneuron excitability and their peak torque measurements. Ice application to the joint did not alter the peroneus longus or the tibialis anterior.