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Biomedical subjects

U Bergh

Publications and source records attributed to U Bergh.

At least 19 recordsLinked to original sources
PubMed1997

A 33-yr follow-up of peak oxygen uptake and related variables of former physical education students.

In 1949, 27 female and 26 male physical education students were studied at a mean age of 22 and 25 yr, respectively. They were restudied in 1970 and 1982. Measurements included oxygen uptake, heart rate, and pulmonary ventilation during submaximal and maximal exercise on a cycle ergometer and treadmill. After 21 yr, peak aerobic power was significantly reduced, from 2.90 to 2.18 l/min and from 4.09 to 3.28 l/min for women and men, respectively. After another 12 yr, the 1970 maxima were not reduced further. From 1949 to 1982 there was a decrease in peak heart rate from 196 to 177 beats/min in women and from 190 to 175 beats/min in men (P < 0.05). Highest pulmonary ventilation did not change significantly. At an oxygen uptake of 1.5 l/min, the heart rate was the same in 1949 as in 1982. In conclusion, the physical fitness level of the subjects was well above average for these ages. From 1970 to 1982 there was no decline in the average peak aerobic power, a finding possibly related to increased habitual physical activity.

Adult↗
PubMed1992

Influence of body mass on cross-country ski racing performance.

The influence of body mass on cross-country skiing performance was evaluated by (i) a theoretical analysis of the relationship between body mass (M) and on one hand the maximal aerobic power and on the other the power expense of skiing, (ii) timing skiers in varied terrain during ski racing, (iii) comparing racing success between light and heavy skiers, and (iv) relating maximal aerobic power of skiers and power expense of skiing to body mass. The theoretical analysis indicated that the maximal aerobic power scaled with M2/3, while the mass exponent for the power expenses ranged from 1/3 to 1. The net result was that heavy skiers appear to be favored in all types of terrain but the steep uphills. During ski racing, heavy skiers displayed a tendency to be faster in all types of terrain, although no statistically significant effect was found. The racing success tended to be greater in heavy skiers among males but not among females. During skiing, maximal aerobic power and the power expense of skiing scaled with M0.7 and M0.4, respectively, indicating an advantage for the heavy skier. Altogether, these observations indicate that heavy skiers are favored, but also that other factors are more important than body mass for cross-country ski racing performance.

Body Height↗
PubMed1991

The relationship between body mass and oxygen uptake during running in humans.

Oxygen uptake during treadmill running was measured at submaximal and maximal intensities in six different groups of endurance athletes (N = 134) and in seven endurance-trained men. The relationship between body mass (M) and oxygen uptake (VO2) was evaluated by deriving the exponent b in the equation VO2 = a.Mb. Thus, if b = 1, the oxygen uptake increases in proportion to body mass and oxygen uptake per kg is independent of body mass; if b less than 1, than the oxygen uptake per kg is inversely related to body mass. The exponent b was found to be less than unity for all groups for both submaximal (b = 0.76, s = 0.06) and maximal oxygen uptake (b = 0.71, s = 0.05). These results indicate that neither submaximal nor maximal oxygen uptake increases in proportion to body mass during running. The relationship between submaximal oxygen uptake and body mass observed in this study may explain why the oxygen uptake per kg of body mass has been found to be higher for children than for adults.

Adolescent↗
PubMed1987

The influence of body mass in cross-country skiing.

The influence of body weight on the performance in cross-country skiing has been studied by: dimensional analysis of the ratio (R) between the factors of importance to power production (VO2max, acceleration of gravity) and the braking powers, e.g., friction and air resistance; measuring the energy cost of level skiing (N = 6); comparing male world class skiers (N = 5) with less successful ones (N = 34) and female winners of the National Championships (N = 9) with non-winners (N = 9) in regard to the relationship between body weight and VO2max. The dimensional analysis revealed that R was less than unity for rather steep uphills. For level, downhill, and less steep uphill skiing, R was greater than unity. Thus, skiers who are light will be favored in steep uphill slopes, whereas heavier skiers have advantages in the other parts of the track. Energy cost per kilogram for level skiing was inversely related to the transported mass. Per unit of distance, this cost was positively related to velocity. The world class skiers displayed significantly greater VO2max than the less successful ones, regardless of the unit used. The lowest standard deviation among the world class skiers was attained when expressing VO2max as ml X min-1 X kg-2/3. The present results indicate that R will be quite close to unity and therefore the performance capability would theoretically be independent of body mass. Furthermore, VO2max is preferably expressed as ml X min-1 X kg-2/3 for cross-country skiers.

Body Weight↗
PubMed1986

Temperature-induced changes in metabolic and hormonal responses to intensive dynamic exercise.

Seven male subjects performed intensive cycle exercise to exhaustion at subnormal muscle temperature (Tm, 29 +/- 2.8 degrees C). Exercise at exactly the same rate of exercise and duration (370 +/- 34 W, 1.5 +/- 0.15 min) was then repeated with normal Tm (35 +/- 0.9 degrees C). During exercise both the arterial (a) and femoral venous (fv) contents of oxygen were significantly higher at subnormal than at normal Tm, because of the higher haemoglobin concentration, but the a-fv oxygen difference was the same in the two situations. The rate of increase in lactate concentration in both arterial and venous blood during exercise was the same in two situations. During exercise the plasma concentrations of adrenaline and noradrenaline in arterial and venous blood were significantly higher at subnormal than at normal Tm. At rest and after exercise the calf blood flow was significantly reduced at subnormal Tm. At the end of exercise the concentrations of glucose-6-phosphate and lactate in the muscle were significantly higher at subnormal Tm than in the muscle of normal temperature. These findings suggest that there was a greater increase in glycolysis in the muscle of subnormal temperature during exercise, possibly as a result of impaired work efficiency and/or reduced blood flow in the cold muscle.

Adult↗
PubMed1984

Influence of low muscle temperature on muscle metabolism during intense dynamic exercise.

Eight males performed intense leg cycle exercise at a constant rate of work averaging 350 W, according to three different protocols: 1) "Cold exhaustive" exercise (initial muscle temperature (Tm) = 29 degrees C), 2) "Warm non-exhaustive" exercise (initial Tm = 34 degrees C) for the same period of time as in 1), and 3) "Warm exhaustive" (initial Tm = 34 degrees C). In five subjects the concentration of various muscle metabolites was determined before and immediately, 1 min, and 5 min after exercise. Blood lactate concentration was determined before and repeatedly after exercise. At low Tm maximal work time was considerably shorter for all subjects compared to normal Tm, 1.3 and 2.1 min, respectively. Comparing conditions 1) and 2) oxygen deficit and the decrease in ATP and CP content were the same in the two experiments. There was a significantly higher concentration of glucose-6-phosphate 17.6 +/- 10.1 and 8.0 +/- 6.2 mmol X kg dw-1, respectively, and a tendency to higher lactate concentration 60 +/- 36 and 33 +/- 14 mmol X kg dw-1, respectively, immediately after exercise in the "cold exhaustive exercise". Peak blood lactate concentration appeared significantly later after "cold exhaustive" exercise indicating a slower elimination rate of lactate from the muscle compared to "warm non-exhaustive" exercise. The reduction in performance observed at low Tm may partially be explained by an increased accumulation rate of lactate in four of five subjects.

Adolescent↗
PubMed1979

Influence of muscle temperature on maximal muscle strength and power output in human skeletal muscles.

The influence of muscle temperature (Tm) on maximal muscle strength, power output, jumping, and sprinting performance was evaluated in four male subjects. In one of the subjects the electromyogram (EMG) was recorded from M. vastus lateralis, M. biceps femoris, and M. semitendinosus. Tm ranged from 30.0 degrees C to 39 degrees C. Maximal dynamic strength, power output, jumping, and sprinting performance were positively related to Tm. The changes were in the same order of magnitude for all these parameters (4-6% x degrees C-1) Maximal isometric strength decreased by 2% x degrees C-1 with decreasing Tm. The force-velocity relationship was shifted to the left at subnormal Tm. Thus in short term exercises, such as jumping and sprinting, performance is reduced at low Tm and enhanced at Tm above normal, primarily as a result of a variation in maximal dynamic strength.

Adult↗
PubMed1979

Physical performance and peak aerobic power at different body temperatures.

In eight male subjects we studied the effect of different core (esophageal, (Tes 34.9--38.4 degrees C) and muscle (Tm 35.1--39.3 degrees C) temperature on 1) physical performance (time to exhaustion at a standard maximal rate of work, WT), 2) aerobic power (VO2), 3) heart rate (HR), and 4) blood lactate (LA) concentration during exhaustive combined arm and leg exercise. In three subjects the effects at different mean skin temperatures (Tsk 27 and 31 degrees C, respectively) were also studied. Peak VO2 was positively correlated to both Tes (r = 0.88) and Tm (r = 0.91). None of the subjects attained control VO2max at Tes and Tm lower than 37.5 and 38.0 degrees C, respectively. HR was correlated to both Tes (r = 0.97) and Tm (r = 0.95). Different Tsk did not affect peak VO2 and HR at subnormal body temperatures. Pulmonary ventilation was independent of Tes and Tm in all experimental situations. LA was significantly higher at Tes 37.5 degrees C compared to both Tes 34.9 and 38.5 degrees C, respectively. At Tes less than 37.5 degrees C and Tm less than 38.0 degrees C, there was a linear reduction in WT (20%.degrees C-1), peak VO2 (5--6%.degrees C-1), and HR (8 beats.min-1.degrees C-1) with lowered Tes and Tm.

Adult↗
PubMed1978

Maximal oxygen uptake and muscle fiber types in trained and untrained humans.

Maximal oxygen uptake (Vo2 max) was determined in 138 male and 41 female human subjects and muscle fiber composition (gastrocnemius and vastus lateralis) in 53 of the males. Highest values for Vo2 max were 7.38 1 x min-1 and 4.341 x min-1 in males and females, respectively. In relation to body weight the highest values were 94 and 77 ml x (kg x min)-1. Athletes participating in endurance events had very high Vo2 max and predominantly slow twitch (ST) fiber populations whereas weight lifters attained rather low values for Vo2 max and had a higher percentage of fast twitch (FT) fibers. Among subjects with the same fiber composition, Vo2 max was higher in the athletes than in the moderately trained. All groups taken together demonstrated a positive relationship between Vo2 max and the relative number of ST fibers (r = 0.67). For endurance and strength athletes r = 0.72 and for the moderately trained r = 0.34, both correlation coefficients being significant.

Body Weight↗
PubMed1976

Maximal oxygen uptake during exercise with various combinations of arm and leg work.

Oxygen uptake (VO2) was determined in 10 males during the following types of maximal exercise (work time: about 5 min): uphill running, bicycling, arm work (cranking), and combined arm work and bicycling (A + L). The A + L exercise was performed in four different ways, the arms doing 10%, 20%, 30%, or 40% of the same total rate of work; and also with the maximal bicycle work load plus either maximal or submaximal arm work. VO2 was the same in running as in all types of A + L exercise, except when the arm work load was 10% and 40% of the total rate of work, where VO2 was 2.5% (P less than 0.05) and 9.4% (P less than 0.001) lower, respectively. Bicycle VO2 was lower than VO2 in running but equal to A + L VO2 when arm work intensity was 40% of the total rate of work. It is concluded that VO2 during maximal exercise a) to a certain extent depends on the exercising muscle mass, b) is lower than the oxygen-consuming potential of the muscles involved in A + L exercise, and c) in A + L exercise is influenced by the ratio of arm work to total rate of work and the subject's fitness for arm work and bicycling.

Adult↗