Biomedical subjects

Timothy J Doherty

Publications and source records attributed to Timothy J Doherty.

3 recordsLinked to original sources

PubMed2003

Decomposition-based quantitative electromyography: methods and initial normative data in five muscles.

Quantitative electromyographic (EMG) techniques provide clinically useful information to aid in the diagnosis and follow the course or response to treatment of diseases affecting the motor system. The purpose of this study was to describe a decomposition-based quantitative electromyography method (DQEMG) designed to obtain clinically applicable information relating to motor unit potential (MUP) size and configuration, and motor unit (MU) firing characteristics. Additionally, preliminary normative data were obtained from the deltoid, biceps brachii, first dorsal interosseous, vastus medialis, and tibialis anterior muscles of 13 control subjects. DQEMG was capable of efficiently and accurately extracting MUP data from complex interference patterns during mild to moderate contractions. MUP amplitude, surface-detected MUP (S-MUP) amplitude, MUP duration, number of phases, and MU firing frequencies varied significantly across muscles. The mean parameter values for the individual muscles studied were similar to previous reports based on other quantitative methods. The main advantages of this method are the speed of data acquisition and processing, the ability to obtain MUPs from MUs with low and higher recruitment thresholds, and the ability to obtain both S-MUP or macro-MUP data as well as MU firing rate information.

Adult↗

PubMed2003

Invited review: Aging and sarcopenia.

Aging is associated with progressive loss of neuromuscular function that often leads to progressive disability and loss of independence. The term sarcopenia is now commonly used to describe the loss of skeletal muscle mass and strength that occurs in concert with biological aging. By the seventh and eighth decade of life, maximal voluntary contractile strength is decreased, on average, by 20-40% for both men and women in proximal and distal muscles. Although age-associated decreases in strength per unit muscle mass, or muscle quality, may play a role, the majority of strength loss can be accounted for by decreased muscle mass. Multiple factors lead to the development of sarcopenia and the associated impact on function. Loss of skeletal muscle fibers secondary to decreased numbers of motoneurons appears to be a major contributing influence, but other factors, including decreased physical activity, altered hormonal status, decreased total caloric and protein intake, inflammatory mediators, and factors leading to altered protein synthesis, must also be considered. The prevalence of sarcopenia, which may be as high as 30% for those >/=60 yr, will increase as the percentage of the very old continues to grow in our populations. The link between sarcopenia and disability among elderly men and women highlights the need for continued research into the development of the most effective interventions to prevent or at least partially reverse sarcopenia, including the role of resistance exercise and other novel pharmacological and nutritional interventions.

Age Distribution↗

PubMed2002

A moderate dose of pseudoephedrine does not alter muscle contraction strength or anaerobic power.

OBJECTIVE: To investigate the effect of an acute oral administration of pseudoephedrine (PSE) on muscle function, fatigue, and anaerobic power output. DESIGN AND MATERIALS: Healthy males (N = 10) and females (N = 10) were allocated to receive both a placebo and PSE (120 mg) using a randomized, double-blind, crossover experimental design. Each subject had their maximal voluntary contraction strength and fatigability measured for both handgrip and ankle dorsi-flexion. Following the strength measurements, a 30-second maximal cycle test was performed to determine lower extremity anaerobic power and fatigue. Plasma lactate was measured before and after exercise. RESULTS: There were no significant differences in any of the outcome variables between the placebo and PSE trials. CONCLUSIONS: These results demonstrated that a 120 mg dose of PSE did not enhance force production, time to fatigue, fatigue index, or power output in young men or women. Therefore, there does not appear to be an ergogenic benefit from the ingestion of 120 mg PSE in high-intensity exercise performance.

Adult↗