The effect of marathon running on carnitine metabolism and on some aspects of muscle mitochondrial activities and antioxidant mechanisms

Carnitine is an essential co-factor in the catabolism of fats as an energy source. The primary purpose of this study was to investigate the effect of running a marathon on the metabolism of carnitine by endurance-trained athletes, and to evaluate the effect of carnitine administration on the performance of such exercise. The effects of marathon running on mitochondrial enzymes and cellular anti-oxidants were also examined to assess whether the expression of these activities is altered by exercise. Subjects were 10 experienced male marathon runners aged between 19 and 25 years. Running a marathon caused a fall in the plasma content of unesterified carnitine (37%) and an increase in the level of acetylcarnitine present (288%). Loading of the athletes with L-carnitine for 10 days before running a marathon abolished the exercise-induced fall in plasma-free carnitine (P less than 0.05) whilst amplifying the production of acetylcarnitine (P less than 0.05). Carnitine loading of the athletes studied made no detectable improvement in performance of the marathon (P greater than 0.05). Cytochrome oxidase, succinate cytochrome C reductase and superoxide dismutase activities present in skeletal muscle were unaltered by marathon running. However, such exercise caused a large increase in the tissue content of oxidized glutathione (189%) at the expense of reduced glutathione (-18%).     

The effect of varied stride rate upon shank deceleration in running

The purpose of this study was to determine the effects of systematic changes in stride rate and length at a given running speed on the peak shank deceleration (PSD) experienced during ground contact. Data were collected from 10 well-trained subjects as they ran on a treadmill at a pace of 3.8 m s-1 (7-min mile-1). Shank deceleration was measured by a lightweight accelerometer which was tightly attached over the distal medial tibia. High-speed films (200 Hz) were taken from a side view to quantify modifications in sagittal plane movement which might have accompanied the stride rate changes. Five stride rate conditions were randomly presented - 10% slower, 5% slower, normal, 5% faster and 10% faster. Average PSD was computed from 10 steps during each condition and testing was repeated on three different occasions. For each session, PSD observed for each condition was normalized to that observed at the normal stride rate in order to minimize the effects of variations in attachment of the accelerometer between and within subjects. The normalized PSD results at each stride rate tested were - normal = 1.0, 10% slower = 1.09, 5% slower = 1.03, 5% faster = 0.96 and 10% faster = 0.91. Significant differences were found between all these means except normal and 5% slower. The kinematic analysis revealed non-significant results for hip, knee and ankle joint angles at touchdown for the various stride rates. Application of the findings to existing analytical models indicated that, for a given running speed, peak impact forces in the ankle and knee joints decreased as stride rate increased.     

More like real life-Motivational methods of teaching in upper secondary school

Motivational methods of teaching are topical subjects and much discussed issues regarding schools and education. The first question of our study covers student motivation and students＇ perception of their own schools＇ teaching methods. The second question reflects on how upper secondary school teachers perceive their roles as teachers, their thoughts on acquirement of knowledge and how learning takes place. The third question treats the subject of how school and education is organized. The upper secondary school the authors chose for the case study is a school that recruits students on a national basis and is directed towards the education of fire and rescue service personnel. The programme follows the national science curriculum and gives qualification for further studies at most universities. The school started in the autumn of 1998 and is known for being successful at working with student involvement, responsibility and subject integration. The study which was conducted during the autumn of 2007 included 32 students from two of the learning groups from the same year and started on the day of introduction of a new theme and finished with their presentation of results. The authors made observations, interviewed and through questionnaires studied how students comprehended the schools＇ working methods. We also interviewed their teachers and headmaster. The theoretic standpoint is Activity Theory （Chaiklin, S. ＆ Lave, J. 1996; Knutagard, H., 2002; Vygotsky, L. S., 1986）. The conclusions are that the students are encuitured into a school＇s activities that are similar to what students perceive as that of real life. It gives meaning and motivation to learning and makes it meaningful. They identify their own responsibility and cooperative learning as the most important parts. The teachers＇ own learning process and planning work is parallel to the work forms applicable to the students. They are all interdependent of each other since all the work areas are thematic. The school can be seen as an activity system where members interplay and communication develops a common culture.