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M J Plyley

Publications and source records attributed to M J Plyley.

47 records · Page 3Linked to original sources
PubMed1987

A histochemical method for the simultaneous demonstration of capillaries and fiber type in skeletal muscle.

A modified ATPase method for the simultaneous demonstration of capillaries and fiber types in skeletal muscle is presented. Muscle biopsies were obtained from mice, hamsters, rats, cats, and dogs, quick frozen, and sectioned at 8 microns in a cryostat. The frozen slides were fixed in a neutral formalin solution at 4 C for 5 min, and then incubated at 37 C for 1 hr in a medium containing ATP, Pb2+, and Ca2+ in a tris-maleate buffer (pH 7.2). Dilute (NH4)2S was used as a developer. To test the reliability of the proposed method, serial sections of each biopsy were stained separately for capillaries (amylase-PAS method) and for fiber types by a standard myosin ATPase (m-ATPase) method. Fiber type percent and capillary parameters were determined for each biopsy. No difference in results was observed for parameters determined using the modified ATPase method compared to the standard capillary and fiber type staining methods. This modified technique is therefore suitable for the simultaneous demonstration of capillaries and fiber types in skeletal muscle.

Adenosine Triphosphatases↗
PubMed1984

Cardiorespiratory and metabolic responses during Tai Chi Chuan exercise.

Tai Chi Chuan is a form of traditional Chinese exercise which has been widely practised in China for preventive and therapeutic purposes. The present study was designed to determine the physiological demands of this exercise modality. Eleven healthy males, aged 28.4 years, were studied for oxygen cost and related metabolic variables, heart rate and blood pressure during the performance of the Long-Form Tai Chi Chuan of Yang's style. Data was collected by an automated respiratory gas analyzer (Jeger Ergooxyscreen) and ECG telemetry during a 17-25 minute performance session (X = 22 minutes). The average energy cost for the Long-Form Tai Chi Chuan was 4.1 Mets, corresponding to a mean VO2 value of 1.03 l X min-1 or 14.5 ml X kg-1 X min-1. The mean peak heart rate during the exercises was 134 beats per minute. These values suggest that the Long-Form Tai Chi Chuan may be classed as moderate exercise, and its intensity does not exceed 50% of the individual's maximum oxygen intake.

Adult↗
PubMed1982

The consistency of cardiac output measurement (CO2 rebreathe) in children during exercise.

Exercise cardiac output (Q) was determined using the CO2 rebreathing equilibrium method. Five repeat tests in 12 boys and two tests over a 4 month interval in 47 boys were performed. Regression equations to predict Q from VO2 were in close agreement with dye dilution studies in boys (Eriksson and Koch 1973). Group mean data were reproducible from trial to trial. The day-to-day variability of Q, with a coefficient of variation of 7-8%, was found to be higher than when the CO2 method has been applied in adults. This greater variability was related, in part, to a larger biological variation in children as depicted in such relatively simple measures as submaximal exercise heart rate. The larger variability was also related to inaccuracies in the methods of PaCO2 estimation in children. Estimation from end-tidal CO2 concentrations requires further research to establish a correction for the alveolar-arterial gradient during exercise in children. Estimation of the child's dead space in exercise, with subsequent derivation of PaCO2 from the Bohr equation, also could be improved. Nevertheless, Q estimates in children exercising above VO2 1.01 X min-1 showed a day-to-day and long term stability acceptable for use in research and clinical studies.

Adolescent↗
PubMed1982

Muscle glycogen storage and its relationship with water.

This study examined the relationship between muscle glycogen and muscle water content. Exercise dietary manipulations were used to vary skeletal muscle glycogen levels in four groups of rodents: (1) eight animals were sedentary controls (SC); (2) ten animals were treadmill familiarized and allowed to recover 24 h before sacrifice (F); (3) ten animals were treadmill familiarized and exercised to exhaustion (E); (4) ten animals were treadmill familiarized, exercised to exhaustion, and allowed to recover with food and water ad libitum for 72 h (ER). All animals were sacrificed in a resting state to normalize intracellular, extracellular, and interstitial water compartments; thus, the E group was sacrificed 45 m in following their run. The treatments altered skeletal muscle glycogen to values ranging from 10.0 to 30.2 mumol glucosyl units/g wet tissue weight. Neither muscle triglyceride nor protein levels were affected by the treatments. Muscle water content expressed as mumol H2O lost/g wet tissue weight or made relative to protein content showed no consistent relationship to the glycogen content. These data, therefore, do not support the commonly accepted muscle glycogen-to-water ratio of 1.0:2.7 (g:g). Further work is necessary to quantify the exact amount of water that is actually associated with the glycogen complex.

Animals↗
PubMed1975

Geometrical distribution of capillaries in mammalian striated muscle.

Striated muscles of hindlimb, jaw, or tongue in dogs, cats, rabbits, rats, and guinea pigs were perfused under high pressure with Microfil (a silicone elastomer of viscosity 20 cP approx.) to outline the vascular bed. When the material had set, the muscles were fixed in formalin. Exmination of histological sections, strained by a modified Gomori trichrome method, showed capillaries containing Microfil as well as some, unperfused, filled with red cells. From well-perfused bundles the numbers of capillaries surrounding each fiber were counted; in all muscles these ranged from 0 to 9 with mean values betweeen 3.2 and 4.0. This was true of both red and white muscle. The mean number of fibers sharing one capillary ranged from 2.0 to 3.2, the lower value being found when four vessels surrounded a fiber and the higher value when there was only three. The results indicate a continuum of transitional models from a square array of fibers with each capillary between two adjacent fibers to a hexagonal array with capillaries at alternate vertices.

Animals↗
PubMedDate not supplied

Central and peripheral adaptations after 12 weeks of exercise training in post-coronary artery bypass surgery patients.

PURPOSE: Training adaptations in patients with coronary artery disease (CAD) have been reported previously, but little is known about central and peripheral adaptations in those recovering from coronary artery bypass graft surgery (CABG). The purpose of this study was to examine the effects of 12 weeks of endurance exercise training on exercise performance and left ventricular and peripheral vascular reserve in a group of uncomplicated CABG patients. METHODS: Thirty-one patients were recruited and began training 8 to 10 weeks after uncomplicated CABG. Patients underwent progressive exercise training consisting of walking and jogging, at 75% to 80% maximal oxygen intake (VO2max). Measures of left ventricular function included ejection fraction (EF), ventricular volumes, and the pressure volume ratio, an index of contractility. Peak ischemic exercise calf blood flow and vascular conductance was determined using strain-gauge plethysmography. Maximal oxygen intake and submaximal blood lactate concentration also was determined. RESULTS: A significant improvement in VO2max (1497 +/- 60 mL/min versus 1691 +/- 71 mL/min) was observed after training. This change was accompanied by an increase in the EF during submaximal exercise (60 +/- 3% versus 63 +/- 2% at 40% VO2max; 61 +/- 3% versus 64 +/- 3% at 70% VO2max) (P < 0.05), and the change in EF from rest to exercise (delta EF). No changes were observed for ventricular volumes during exercise, although there was a trend for a higher stroke volume at 70% VO2max. A significant increase (18%) was observed for peak ischemic exercise calf blood flow and vascular conductance. In addition, submaximal blood lactate concentration was lower after training. CONCLUSIONS: These data indicate that exercise training for 12 weeks in patients recovering from CABG can elicit significant improvements in functional capacity that, for the most part, are secondary to peripheral adaptations, with limited support for improvement in left ventricular function.

Adaptation, Physiological↗
PubMedDate not supplied

Isokinetic rehabilitation after surgery. A review of factors which are important for developing physiotherapeutic techniques after knee surgery.

The postoperative rehabilitation of individuals who've had surgery has been a primary concern of all members of the health care community. With the advent of new training devices for use during the rehabilitation period (i.e., isokinetic training devices) and new research in sports medicine, there has been a renewed interest in how to best rehabilitate individuals following surgery (knee surgery, in particular). This paper briefly reviews basic muscle physiology as it relates to muscle fiber types and recruitment patterns. Subsequently, it reviews studies that have investigated muscle atrophy and methods to reduce muscle dysfunction related to surgery, immobilization, and disuse. Finally, it reviews isokinetic training studies and examines the concept of "specificity of speed" training. These principles of muscle physiology and muscle plasticity are then applied to a proposed isokinetic rehabilitation program which might be adapted for use following joint surgery.

Atrophy↗