Browsing by Subject "muscle"

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  • Kylä-Puhju, Maria; Ruusunen, Marita; Puolanne, Eero (Elsevier, 2005)
    The activity of glycogen debranching enzyme (GDE) was studied in relation to pH value and temperature in porcine masseter and longissimus dorsi muscles. A glycogen limit dextrin was used as the substrate for GDE, and the enzyme was derived from raw meat extracts. In both muscles, the pH only weakly affected on activity of GDE at the pH values found in carcasses post-slaughter. However, the activity of GDE decreased strongly (P < 0.001) when the temperature decreased from values of 39 °C and 42 °C found just after slaughter to values of 4 °C and 15 °C found during cooling. In both muscles the activity of GDE began to fall at temperatures below 39 °C and was almost zero when the temperature decreased to below 15 °C. Thus, the activity of GDE may control the rate of glycogenolysis and glycolysis, but does not block rapid glycolysis and pH decrease when the temperature is high. This may be important in PSE meat, where the pH decreases rapidly at high temperatures, but rapid cooling could limit the activity of GDE and thus glycogenolysis. As expected, GDE was more active in the light longissimus dorsi muscle than in the dark masseter muscle.
  • McGowan, Catherine Marie; Hyytiäinen, Heli Katariina (2017)
    Athletic performance or the kinematics of locomotion is ultimately the result of the actions of muscles. Muscular actions differ depending on the muscle group involved with anatomical and functional properties depending on the primary roles of the muscle; from stabilisation to powering locomotion. The functional (contractile and metabolic) properties of a muscle are determined by its fibre type or relative fibre type proportions in the muscle. The actions of muscle require the coordination of the nervous system with muscle contraction to produce movement or resist movement to avoid unwanted motion and tissue damage. The coordination of muscular action with the nervous system is termed neuromotor control and it requires precise proprioceptive input from the periphery, processing and input from the central nervous system (including learned or trained movements) and involves timing of muscle recruitment as well as muscle contraction. Training of muscles involves training for strength (or force generation) and stamina with measureable physiological changes with training including increased fibre size, alterations in fibre type, alterations in glycogen concentrations and lactate transport and alterations in mitochondrial and capillary density. As well as standard athletic training, skills training can make the difference in athletic performance and injury prevention in the equine athlete. This involves training of neuromotor control; training motor skills by motor relearning and conditional learning. Practical specific training techniques can be used in injury prevention, rehabilitation post injury and maintenance of the athlete. In this review we will focus on the thoracolumbar and hindlimb areas of the horse and review the importance of muscular control of locomotion, neuromotor control, the physiological effects of training and practical ways to maximise performance potential by specific physiotherapy skills training.
  • Kylä-Puhju, Maria; Ruusunen, Marita; Kivikari, Riitta; Puolanne, Eero (Elsevier, 2004)
    The aim of this study was to investigate the buffering capacity (BC) of five porcine muscles. The pH of muscles with zero lactate was also estimated. The BC was calculated on the basis of the amount of lactate accumulating in the muscle between two sampling times and the simultaneous pH decline. Two muscle samples were obtained from each muscle (n=13-36): one as soon as possible after slaughter and the other 24 h post-mortem. The BCs (mmol lactate/(pH*kg)) were in the light gluteus superficialis, longissimus dorsi and semimembranosus muscles 48.3±8.8, 48.6±9.2 and 46.8±13.0, and in the dark infraspinatus and masseter muscles 45.3±13.1 and 32.0±11.5, respectively. The dark masseter muscle differed significantly from the other muscles studied (p<0.01). The estimated pH values of muscles with zero lactate were in the gluteus, longissimus dorsi, semimembranosus muscles 7.14±0.06; 7.18±0.06; 7.38±0.08, and in the infraspinatus and masseter muscles 6.87±0.07; 7.03±0.08, respectively. It was suggested since lactate is continuously formed in the muscles, the resting pH of living light and dark muscles may, however, be the same. The approach used in this study to determine the BC resulted in values which are close to values previously reported in the literature (measured by using titration curves).