Instantaneous quantification of skeletal muscle activation, power production, and fatigue during cycle ergometry.

A rapid switch from hyperbolic to isokinetic cycling allows the velocity-specific decline in maximal power to be measured, i.e., fatigue. We reasoned that, should the baseline relationship between isokinetic power (Piso) and electromyography (EMG) be reproducible, then contributions to fatigue may be isolated from 1) the decline in muscle activation (muscle activation fatigue); and 2) the decline in Piso at a given activation (muscle fatigue). We hypothesized that the EMG-Piso relationship is linear, velocity dependent, and reliable for instantaneous fatigue assessment at intolerance during and following whole body exercise. Healthy participants (n = 13) completed short (5 s) variable-effort isokinetic bouts at 50, 70, and 100 rpm to characterize baseline EMG-Piso. Repeated ramp incremental exercise tests were terminated with maximal isokinetic cycling (5 s) at 70 rpm. Individual baseline EMG-Piso relationships were linear (r(2) = 0.95 ± 0.04) and velocity dependent (analysis of covariance). Piso at intolerance (two legs, 335 ± 88 W) was ∼45% less than baseline [630 ± 156 W, confidence interval of the difference (CIDifference) 211, 380 W, P < 0.05]. Following intolerance, Piso recovered rapidly (F = 44.1; P < 0.05; η(2) = 0.79): power was reduced (P < 0.05) vs. baseline only at 0-min (CIDifference 80, 201 W) and 1-min recovery (CIDifference 13, 80 W). Activation fatigue and muscle fatigue (one leg) were 97 ± 55 and 60 ± 50 W, respectively. Mean bias ± limits of agreement for reproducibility were as follows: baseline Piso 1 ± 30 W; Piso at 0-min recovery 3 ± 35 W; and EMG at Piso 3 ± 14%. EMG power is linear, velocity dependent, and reproducible. Deviation from this relationship at the limit of tolerance can quantify the "activation" and "muscle" related components of fatigue during cycling.

On the determination of ventilatory threshold and respiratory compensation point via respiratory frequency.

This study examined the validity of a quantitative respiratory frequency (f(R)) analysis to detect the ventilatory threshold (theta(Vent)) and respiratory compensation point (RCP). Thirty-six amateur competitive cyclists completed a maximal graded exercise test on an electromagnetically-braked cycle ergometer. theta(Vent) and RCP were determined using multiple gas exchange criteria and by f(R) analysis (theta(Vent)f(R) and RCP(f(R))), employing an iterative least-squares linear regression technique. Fifteen subjects were excluded from the analyses due to a low signal-to-noise ratio and/or high risk for pseudo-threshold resulting from hyperventilation early in the exercise protocol. A Bland-Altman procedure for inter-analysis comparison completed on the remaining participants' data (n=21; age=29+/-7 years; height=177+/-9 cm; weight=76.0+/-15.8 kg; VO(2max)=4.415+/-0.971 lmin(-1); 58.7+/-10.7 ml kg(-1) min(-1)) revealed mean bias+/-95% Limits of Agreement (LOA) of 1.53+/-50.2 W for theta(Vent) and theta(Vent)f(R). The same inter-anlysis comparison (n=21) for RCP and RCP(f(R)) resulted in a mean bias+/-LOA of 12.6+/-26.9 W. The analysis techniques in the present investigation revealed substantial limits of agreement and/or bias for all estimations, and these data indicated f(R) analyses were unsatisfactory to determine theta(Vent) and RCP in trained cyclists.

Lumbosacral epidural steroid injections.

Epidural steroid injections for the treatment of low back pain and associated leg pain have been used for half a century. Initial use was empirical and not without controversy. An abundant literature has accumulated describing their use and potential benefit. Previous controlled studies are limited by methodology and technique. A growing body of literature suggests that they exert some of their clinical effect by reducing epidural and perineural inflammation. More current studies using fluoroscopy with radiographic contrast and precise epidural steroid placement suggests they may obviate surgery in some patients with true radicular pain.

Topical capsaicin as an adjuvant analgesic for the treatment of traumatic amputee neurogenic residual limb pain.

The treatment of amputee residual limb pain can at times be a challenge for the physician. Occasionally, traditional analgesic medication regimens cannot be used or are ineffective in relieving the pain. Topical capsaicin cream has been a beneficial adjuvant medication in the treatment of some painful conditions. The authors present three patients with traumatic upper limb amputations where topical capsaicin cream was of benefit in the treatment of neurogenic residual limb pain. The hope is that these cases will increase awareness of the potential use of capsaicin cream as an adjuvant analgesic in patients with residual limb pain. Common causes of residual limb pain and the pharmacology of capsaicin cream are discussed.

Case report: lymphangitic carcinomatosis from cervical carcinoma--an unusual presentation of diffuse interstitial lung disease.

Pulmonary lymphangitic carcinomatosis is an unusual presentation of diffuse infiltrative lung disease. In this report, we present a case secondary to cervical carcinoma that has been previously reported in only four patients. The diagnosis was made by transbronchial lung biopsy.