Search PubMed⌕ Search

Biomedical subjects

B Ekblom

Publications and source records attributed to B Ekblom.

18 recordsLinked to original sources
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

Influence of age and physical activity on central hemodynamics and lung function in active adults.

Five female and seven male physically active adults were studied twice within a 13-yr interval. The individual state of physical activity was mainly unchanged. Maximal oxygen uptake (VO2 max) was reduced in all subjects except one female, in whom it remained unchanged. During maximal exercise, cardiac output (Q) in males was unchanged. In females, Q was significantly increased due to increased stroke volume (SV). In both sexes, the reduced VO2 max was explained by a smaller arteriovenous O2 difference (mixed venous O2 content (C-VO2) significantly increased). For a given submaximal VO2, Q was increased in both sexes and heart rate was unchanged. Thus, SV was increased and arteriovenous O2 difference was reduced due to increased C-VO2. Another four males were studied several times in various states of physical fitness during an 11-yr period. The reduced VO2 max from peak value was due to a reduced Qmax (SV smaller), whereas the arteriovenous O2 difference and C-VO2 were unchanged. Our results indicate that the observed changes in circulatory response to submaximal and maximal exercise in physically active adults may to a large extent be due to an effect of "detraining."

Adult↗
PubMed1978

Comparisoin between mass spectrometry and Haldane technique in analysing O2 and CO2 concentrations in air gas mixtures.

We have evaluated a mass spectrometer for use as a gas analyser in air gas mixtures. Simultaneous determinations of O2 and CO2 concentrations with both the mass spectrometer and the Haldane technique were done in ninety-nine different samples of expired air from ordinary laboratory experiments. The mean differences (+/- SD) between the two techniques for O2 and CO2 concentrations were 0.003% (+/- 0.049%), and 0.001% (+/- 0.045%) absolute values, respectively, (P greater than 0.05 for both), r values being 0.996 for O2 and 0.994 for CO2. There was a drift in the apparatus, which decreased with operating time. Proper calibration is necessary for accurate readings. A cost-benefit balance is made.

Carbon Dioxide↗
PubMed1977

Low intensity training, inactivity and resumed training in sedentary men.

The effects of a low intensity training regimen, consisting of two 7-week periods with an interspersed 8-week inactivity period were investigated in 16 sedentary men. A follow-up was made on 7 subjects after 38 additional weeks' training. Systemic as well as local effects were studied using exercise tests and leg muscle biopsies. The two 7-week training periods both resulted in a 6% increase in Vo2 max and a lowered heart rate during submaximal work. No persisting training effects were detected by exercise tests after inactivity. In skeletal muscle, however, striking differences in enzyme activity pattern and ultrastructure were observed between the two periods, indicating that some training effect of importance for muscle metabolic adaptation might have persisted during inactivity. It is suggested that such an effect might be associated with the local oxygen supply. During the 38-week training period there was a large increase in muscle metabolic capacity, but no change in maximal oxygen uptake. This separation of systemic and local training effects indicates a lack of a direct causal relationship between muscle metabolic potential and max imal oxygen uptake. It is suggested that the elevated muscle oxidative capacity is of importance for an increased endurance capacity.

Adult↗
PubMed1976

Central circulation during exercise after venesection and reinfusion of red blood cells.

To study central circulation at different levels of hemoglobin (Hb) concentration, five subjects performed submaximal and maximal exercise in three different situations: 1) control, 2) after venesection of 800 ml of whole blood, and 3) after reinfusion of the red blood cells about 30-35 days after venesection. Maximal oxygen uptake (VO2 max) decreased from 4.27 l-min-1) at control to 4.03 l-min-1 after venesection (P less than 0.05) and increased to 4.61 l-min-1 after reinfusion (P less than 0.05). Maximal values on cardiac output (Q), heart rate (HR), and stroke volume (SV) were the same in the three situations. Thus, there was no compensatory increase in Qmax due to the lowered arterial oxygen content (Cao2) after venesection. An increase of the Cao2 (Hb concentration) and a lowering of the Cvo2 contributed equally to the increased VO2 max after reinfusion. At a given submaximal VO2, HR and blood lactates were increased at lowered Hb concentration and decreased at increased Hb concentration over control levels. Correlation coefficient for the change in Q in relation to the acute change in Hb concentration at a given submaximal VO2 was -0.49 (P less than 0.05).

Adult↗
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↗
PubMed1976

Changes in muscle fibre size and physical performance in patients with rheumatoid arthritis after short-term physical training.

Ten patients with rheumatoid arthritis of moderate severity were given 6 weeks' intense physical training. During the investigation period the patients improved their physical performance capacity as well as their rate of perceived exertion. There was an increase in the muscle fibre size, of type I and type II, most pronounced in the latter fibre group. No 'flare-up' of the arthritis could be seen during the training period. Comments are made as to which patients might benefit by a short-term physical training.

Adult↗
PubMed1976

Changes in muscle fibre size and physical performance in patients with rheumatoid arthritis after 7 months physical training.

Ten patients with rheumatoid arthritis of moderate severity were given 7 months' physical training. During the investigation period the patiens improved their physical performance capacity as well as they lowered their rate of perceived exertion during submaximum exercise. There was a small increase in muscle fibre size and a correlation was found between muscle strength and type II fibre size. Clinical examination and X-ray studies did not reveal any further joint destruction during the investigation period.

Adult↗
PubMed1975

Effect of changes in arterial oxygen content on circulation and physical performance.

To evaluate the effect of different levels of arterial oxygen content on hemodynamic parameters during exercise nine subjects performed submaximal bicycle or treadmill exercise and maximal treadmill exercise under three different experimental conditions: 1) breathing room air (control); 2) breathing 50% oxygen (hyperoxia); 3) after rebreathing a carbon monoxide gas mixture (hypoxia). Maximal oxygen consumption (Vo2 max) was significantly higher in hyperoxia (4.99 1/min) and significantly lower in hypoxia (3.80 1/min) than in the control experiment (4.43 1/min). Physical performance changes in parallel with Vo2 max. Maximal cardiac output (Qmax) was similar in hyperoxia as in control but was significantly lower in hypoxia mainly due to a decreased stroke volume. A correlation was found between Vo2 max and transported oxygen, i.e., Cao2 times Amax, thus suggesting that central circulation is an important limiting factor for human maximal aerobic power. During submaximal work HR was decreased in hyperoxia and increased in hypoxia. Corresponding Q values were unchanged except for a reduction during high submaximal exercise in hyperoxia.

Adult↗
PubMed1975

Effect of short-term physical training on patients with rheumatoid arthritis I.

Thirty-four patients with rheumatoid arthritis, aged 38 to 63 years (mean age 56 years), were studied before and after a 6-week stay in hospital. Twenty-three of these patients underwent special physical training twice a day during this period. Physical performance, cardio-respiratory fitness and muscle strength improved significantly in the training group. In the control group there were no major changes in these measurements during this period except for an increase in muscle strength. Perceived exertion during submaximal exercise was much lower in the training group following the conditioning. Joint status was virtually unchanged over the experimental period in both groups. It is postulated that the low physical performance seen in these types of RA patients may, to a large extent, be attributed to lack of physical activity.

Adult↗
PubMed1975

Effect of short-term physical training on patients with rheumatoid arthritis. a six-month follow-up study.

Twenty-three patients with rheumatoid arthritis were retested about 6 months after 5 weeks' physical conditioning and 7 patients from a former control group were also retested. Former training group patients, who had continued to train about 4 times or more per week, had maintained the improved physical status obtained during the initial conditioning, while those patients who had trained less than that or discontinued training, had lost some or most of their improvement. The physical status in the former control group was virtually remained unchanged. Joint status in the former training group was no different at re-test than at post-training or pre-training examinations. A questionnaire, given to the training group patients. Four patients from this group returned to work had positively affected the daily physical activity of these patients. Four patients from this group returned to work after the hospital training program.

Adult↗