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Biomedical subjects

P Tesch

Publications and source records attributed to P Tesch.

28 records · Page 2Linked to original sources
PubMed1978

Muscle fatigue and its relation to lactate accumulation and LDH activity in man.

The lactate concentration in different muscle fibre types was determined in biopsy specimens from human vastus lateralis muscle after 30 and 60 s of maximal dynamic leg exercise. In addition, muscle fibre type distribution, total lactate dehydrogenase (LDH) activity, and isozymes of LDH were determined. In accordance with previous studies (Thorstensson and Karlsson 1976, Nilsson et al. 1977) it was found that an increasing proportion of slow twitch (ST) fibres corresponded to better sustained muscle force. Lactate was found preferentially in fast twitch (FT) fibres after 30 s, but after 60 s this difference was abolished. Differences between the two main muscle fibre types in muscle lactate, total LDH activity, and M-LDH activity were correlated to muscle fatigue. It was concluded that lactate or associated pH changes primarily in FT fibres could be one factor responsible for the impaired muscle function.

Adult↗
PubMed1978

Muscle glycogen depletion and lactate concentration during downhill skiing.

Skilled and unskilled skiers were studied during downhill skiing. Muscle glycogen and muscle lactate concentrations in the vastus lateralis muscle were determined following different skiing conditions. Heavy glycogen utilization was found in the groups studied during a day of skiing. The skilled and unskilled skiers differed with respect to selective glycogen depletion pattern and the skilled subjects demonstrated greater depletion of slow twitch fibers than the unskilled subjects. Lactate concentrations ranged from approximately 5-26 mmoles x kg-1 wet muscle after approximately one minute of maximal skiing. This wide range was not found to be related to the level of skiing proficiency. However, skiing with varyingly angled boots, resulting in different knee angles, did affect lactate concentration. Lactate concentration was positively correlated to individual muscle fiber composition expressed as a percent of fast twitch fibers. The results suggest more pronounced involvement of aerobic energy metabolism in skilled skiers than in unskilled skiers.

Adult↗
PubMed1977

Fatigue and EMG of repeated fast voluntary contractions in man.

A fatigue test consisting of repeated fast maximal contractions of the left quadriceps muscle in an isokinetic apparatus was performed by 12 healthy male subjects (19-25 yrs). EMG signals recorded from the surface of the left vastus lateralis muscle, from which also biopsies were obtained for muscle fibre classification. Only minor changes were observed in the EMG variables despite a decrease in muscle strength performance, in terms of peak torque, work and power to about 50% of initial values after 100 contractions. The concomitantly obtained positive correlation between the increase in EMG/torque ratio and the individual percentage of fast twitch (FT) muscle fibres indicated that local factors in the muscle, primarily in FT fibres, were causing the development of fatigue during repeated dynamic contractions with high power outputs.

Adult↗
PubMed1977

Actomyosin ATPase, myokinase, CPK and LDH in human fast and slow twitch muscle fibres.

The enzyme activities of Mg2+ stimulated ATPase, creatine phosphokinase (CPK), myokinase (MK) and lactate dehydrogenase (LDH) were determined in pooled fast twitch (FT) and slow twitch (ST) human skeletal muscle fibers, dissected out from freeze-dried muscle biopsy material. All enzymes investigated demonstrated higher activities in FT fibres. The ratio in enzyme activity between fibre types was greatest for Mg2+ stimulated ATPase (3:1) and smallest for CPK (1.3:1). In addition, the isozyme patterns of CPK, MK and LDH were studied by means of isoelectric focusing (CPK and MK) and discelectrophoresis (LDH). A difference was observed between fibre types with respect to the isozyme distribution of MK and LDH, whereas the CPK isozyme pattern was similar in both fibre types. These results on separated human FT and ST fibres were essentially in conformity with what has earlier been indicated from experiments on mixed muscle homogenates.

Actomyosin↗
PubMed1977

Lactate in fast and slow twitch skeletal muscle fibres of man during isometric contraction.

Concentration of lactate in fast and slow twitch fibres, respectively, were determined in m. quadriceps femoris after sustained contractions at 25%, 50%, and 75% of maximal voluntary isometric contraction (MVC) until exhaustion as well as after interrupted exercises at 25% and 50% MVC. Maximal lactate concentrations were only found at 50% of MVC performed to exhaustion. Lactate concentration was higher in slow twitch (ST) fibres at 50% MVC compared to in ST fibres at 25% MVC, and higher in fast twitch (FT) fibres at 50% MVC compared to in FT fibres at 75% MVC. After short time isometric exercise (i.e. 75% to exhaustion and 50% and 25% performed for the same period of time as 75% MVC) lactate concentration, expressed as lactate ratio (lactate concentration in FT fibres/lactate concentration in ST fibres) was found to be positively correlated to percent FT fibres (r=0.89). Lactate ratio ranged 0.5-2.0, i.e. at onset of isometric exercise, lactate concentration increase was faster in ST fibres in the muscle rich in ST fibres and faster in FT fibres when the muscle wasrich in FT fibres.

Age Factors↗
PubMed1977

Muscle strength and fiber composition in athletes and sedentary men.

Members of Swedish national teams in track and field events (sprinting and jumping), downhill skiing, race walking, orienteering, and a group of sedentary men were studied to examine the relationship between muslce fiber characteristics in needle biopsy samples form m. vastus lateralis and muscle strength measured as peak torque during isokinectic knee extensions. In comparison with the sedentary group the following differences were found: a) percentage fast twitch fibers was lower in the endurance athetes, b) fast to slow twitch muscle fiber area ratio was higher in the track athletes, c)track athletes and downhill skier attained higher peak torque values at all angular velocities examined. The track athletes had, however, higher torque values at the fastest angular velocity as compared to the downhill skiers, whereas there was no differnce under isometric conditions. The proportion of fast twitch fibers was related to torque produced, especially at high motion velocity. The training also appeared to affect the force-velocity relationship.

Adult↗
PubMed1976

Physiological investigations of Swedish elite canoe competitors.

Maximal as well as submaximal heart rate and oxygen uptake were measured during paddling and other types of arm and leg exercise in Swedish elite canoeists. Muscle fiber composition was determined in the canoeists: 4 seniors (22-28 year old) as well as 2 juniors (18 years). Vo2max during treadmill running averaged in the seniors 5.4 1 x min -1 and during arm exercise. Corresponding values for the juniors were 4.7 1 x min -1 and 4.21 x min -1 or 88%. Paddling 500 m resulted in relatively low oxygen uptake, but the highest blood lactate concentrations, whereas 1,000 m gave the highest oxygen uptake but also high blood lactate concentrations. During a 10,000 m race the heart rate was approximately 97% (range 96-98%) of the maximum measured. In nine present and former winners of World Championships or Olympic medals, fiber types were determined in the deltoid muscle. These data indicated that canoeists, who were successful in 500 m races, had a higher percentage of fast twitch (FT) muscle fibers (range 50-59%) than medalists, who competed in 10,000 m races (26-52% FT).

Adolescent↗