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Biomedical subjects

B Ahlborg

Publications and source records attributed to B Ahlborg.

At least 19 recordsLinked to original sources
PubMed1989

Influence of vibration on endurance of maximal isometric contraction.

In order to investigate how vibration affects endurance during muscular contraction, knee-joint extension efforts were performed with and without superimposed vibrations. Fourteen healthy non-smoking 20-year-old males performed maximal isometric and sustained knee-joint extension efforts (angle 90 degrees) in sitting posture three times with each leg, with or without vibration. The tests were done once with each leg in a randomly chosen order. The frequency of the vibration was 20 Hz and the acceleration 20 m/s2 RMS, applied in a horizontal sagittal direction to the ankle. The endurance was defined as the time in seconds that it took for the exerted force to decrease by 10% of the initial value. The endurance time averages 22.5 s without vibration and 15.8 s with vibration. The vibratory stress reduced endurance by 6.7 +/- 1.84 s (mean +/- SEM) (P less than 0.005). The difference in maximal force recorded initially was 34 +/- 1.9 N (P less than 0.1). Our conclusion is that vibration may decrease the endurance of maximal och sustained isometric muscular contraction.

Adult↗
PubMed1989

Influence of vibration on work performance during ergometer cycling.

With a view to investigating how vibration affects dynamic working capacity, exercise tests were performed both with and without superimposed vibration. The performance of 8 healthy, non-smoking 20-year-old males exercising on a cycle ergometer at a constant load was studied on four occasions, with and without vibration in a randomly chosen order. The frequency of the vibration, which was applied vertically through the pedals, was 20 Hz and the acceleration was 20 m/s2 RMS. The handlebars and saddle of the cycle were insulated from the vibration. The exercise time averaged 47 min with vibration and 60 min without. The vibratory stress reduced the exercise time by 13 +/- 2.9 min (mean +/- SEM) (P less than 0.005). The average heart rate when the exercise was stopped was 180.3 beats/min with vibration and 180.7 beats/min without. The systolic blood pressure after 20 min averaged 188 mm Hg with vibration and 187 mm Hg without vibration. Both with and without vibration, 6 of the 8 subjects stated that leg fatigue was the cause of their inability to continue pedalling longer. Our conclusion is that in the performance of dynamic muscular work endurance may decrease under the influence of vibration.

Adult↗
PubMed1982

Blood pressure variations across areas in the greater Stockholm region: analysis of 74,000 18-year-old men.

74,000 18-year-old men who went through the medical examination for the military draft procedure in the greater Stockholm region during the years 1969-1978 were divided into 63 areas of residence. Means of systolic and diastolic blood pressures, as well as heart rate, height, muscle strength and reasoning test results varied significantly across areas. In a univariate analysis, significant correlations were found between high average systolic blood pressure in an area on one hand and low median income and high proportion of subjects on social welfare in the area on the other hand. In a multivariate analysis these associations were partly explained by a tendency of areas with relatively poor socioeconomic conditions to have high average relative weight, high mean muscle strength and poor average reasoning test results. All of these variables were associated with high average systolic blood pressure. The findings are discussed in relation to ecological mechanisms. Somatic and psychological development during childhood is associated with educational environment at school and leisure activities. Areas with poor socioeconomic conditions and high average systolic blood pressure were those which tended to have high rates of migration.

Adolescent↗
PubMed1980

Significance of primary T wave aberrations in the electrocardiogram of asymptomatic young men. Part 1. Electrocardiographic data.

The electrocardiogram (ECG) at rest and during orthostasis and exercise in 51 healthy men 18-19 years of age without history or symptoms of heart disease, but with T wave aberrations in the ECG (group T) were compared to the normal ECGs of 112 controls of the same age. These aberrations (which literature suggests to be due to organic heart disease) consisted of either a notch in the T wave, especially in the midprecordial leads, that sometimes became inverted, or a low T wave without concomitant ST depression. The T wave aberrations at rest in group T were similar to what 25% of the controls evidenced during orthostasis (group B). Both group T and group B had signs of increased sympathetic tone at rest with a higher heart rate and systolic blood pressure than did the subjects with normal ECG both at rest and during orthostasis. These T wave aberrations disappeared for the majority during exercise. Both group T and group B had prolonged QTc intervals. Group T had increased R wave amplitudes which did not correlate to the severity of the T wave aberration or to systolic blood pressure. Our opinion is that primary T wave aberrations in the majority of these young men were because of increased sympathetic tone.

Adolescent↗
PubMed1980

Significance of primary T wave aberrations in the electrocardiogram of asymptomatic young men. Part II. Working capacity and anthropometric data.

Fifty-one healthy men, 18 - 19 years of age, with "organic" T wave aberrations (group T) were compared to 112 controls of the same age with normal electrocardiograms (Group A + B). Group T had increased heart rate and higher systolic and diastolic blood pressures. Their lower physical work capacity could be "explained" in multivariate analysis by their shorter height, smaller heart volume and lower total hemoglobin (the latter not constituting a significant difference between the groups). Multiple regression analysis indicated that differences in heart rate, systolic blood pressure and blood volumes explained differences between subjects with and without primary T wave aberrations. These variables are all influenced by changes in sympathetic discharge, whereas no variable representing performance or body dimensions contributed to the explanation.

Adolescent↗
PubMed1977

The significance of AV block I in asymptomatic young men. Variability, some anthropometric data, orthostatic test reaction and physical work capacity.

Twenty-nine young men with AV block I (P-R interval greater than 0.22 sec), without any history of heart disease, have been compared with 112 randomly selected healthy men of the same age. In 24 subjects who were free from concomitant ECG changes the P-R interval was normalized during orthostatic test and/or physical exercise. This group did not differ from the controls regarding anthropometric data and physical work capacity except for a higher heart rate at rest, thus suggesting that in these subjects an occurrence of AV block I has no pathological significance. However, it cannot be excluded that the block is a sequela, for instance, to myocarditis. Three subjects with AV block I and inverted T waves in the precordial leads and two subjects with unchanged P-R intervals to increased sympathetic tone had on average a smaller body size, a higher HR and systolic BP in recumbent position and smaller blood volumes.

Adolescent↗