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Biomedical subjects

R A Binkhorst

Publications and source records attributed to R A Binkhorst.

At least 19 recordsLinked to original sources
PubMed2006

Body temperature responses in spinal cord injured individuals during exercise in the cold and heat.

The aim of this study was to assess the effect of arm exercise on the heat balance in spinal cord-injured (SCI) individuals with complete lesions at ambient temperatures of 10 and 35 degrees C. Four SCI with a high lesion (> or = T6) (SCI-H), seven with a low lesion (< T6) (SCI-L), and ten able-bodied controls (AB) performed arm-cranking exercises at 40 % of the maximal power output for 45 min, once in 10 degrees C and once in 35 degrees C. Oxygen uptake, rectal temperature, and skin temperature (chest, upper arm, thigh, calf) were measured at rest and 15, 30, and 45 min after the onset of exercise. Metabolism, heat production, skin temperature, mean body temperature (a combination of rectal and skin temperature), and body heat content were calculated. Heart rate at 10 degrees C was 103 b/min in SCI-H, 120 in SCI-L and 112 in AB, while in 35 degrees C, heart rate was 112 b/min in SCI-H, 144 in SCI-L and 134 in AB. The increase in rectal temperature in 35 degrees C was larger in SCI-L (+ 0.07 degrees C) and SCI-H (+ 0.08 degrees C) than in AB (+ 0.06 degrees C). The decrease in mean body temperature at 10 degrees C was larger in SCI-H (33.0 +/- 0.68 degrees C) than in SCI-L (33.6 +/- 0.29 degrees C) and AB (34.5 +/- 0.31 degrees C). During exercise in 35 degrees C, mean body temperature increased in all three groups. The increase in body temperature in SCI-L was larger than in AB. During exercise in 10 degrees C, body heat content decreased in SCI-H (80.0 +/- 15.1 kJ) and SCI-L (89.2 +/- 9.1 kJ) but remained constant in AB (97.0 +/- 16.1 kJ). During exercise in 35 degrees C, body heat content increased in all three groups. The increase in body heat content after exercising in 35 degrees C was not significantly different between the three groups. In summary, mean body temperature and body heat content in the cold decreased in SCI, despite exercising. In the heat, mean body temperature and body heat content seems to increase more in SCI than in AB. We can conclude that SCI are at a greater risk for a disturbed heat balance during exercise in the cold and in the heat than AB. Both in the cold and in the heat, precautions should be taken even earlier and be more intensive for SCI than for AB.

Adult↗
PubMed1999

Effect of a pulsating anti-gravity suit on peak exercise performance in individual with spinal cord injuries.

The aim of this study was to examine effects of a pulsating pressure anti-gravity suit on the peak values of oxygen uptake (VO2) and power during maximal arm exercise in spinal-cord-injured (SCI) individuals. Five well-trained SCI men (with lesions at levels between T6 and L1) and seven well-trained able-bodied men (ABC) performed two incremental (10 W x min(-1)) arm-cranking tests. During one test the pressure in the anti-G suit pulsated between 4.7 kPa (35 mmHg) and 9.3 kPa (70 mmHg) every 2 s (PPG+), during the other test (PPG-) all the subjects wore the anti-G suit in a deflated state. Tests were performed in a counter-balanced order. Peak VO2 in SCI was 1 ml x kg(-1) x min(-1) lower during PPG+ compared to PPG- (P = 0.05). Peak power and peak heart rate were not significantly different during PPG+ compared to PPG-. These results would suggest that no increase in work capacity can be obtained with a pulsating pressure anti-gravity suit in either SCI or ABC.

Adult↗
PubMed1998

The effects of an ergonomic-educational course. Postural load, perceived physical exertion, and biomechanical errors in nursing.

OBJECTIVES: To evaluate the results of an ergonomic-educational course for nurses we assessed the number and percentage of harmful postures and of ergonomic and biomechanical errors made before and after the course. We also studied the perceived physical exertion. MEANS AND METHODS: In all, 12 nurses who had participated in the course (trainees) and 12 who had not (controls) were recorded on video while performing standardized nursing tasks. The wards from which the two groups of nurses came were comparable, as were the patient populations. The nurses were also comparable in some personal characteristics. The tasks they performed included washing, lifting, and repositioning a patient as well as certain tasks other than patient handling. Video recordings were made once before (1-2 weeks) and twice after the course (after 3 months and after 15 months). The harmful postures, the errors made, and the ratings of perceived exertion were measured by means of the Ovako Working-posture Analysis System (OWAS), a checklist, and Borg scores, respectively. RESULTS: When the first and last measurements of all the above tasks taken as a whole were analyzed the trainees showed a significant improvement in the number and percentage of harmful postures and errors, whereas the controls did not. The same could be concluded for lifting alone. After the course the new work routine did not appear to have caused any extra perceived physical exertion. CONCLUSION: It can be concluded that the course was successful, although it should be carefully investigated as to whether nurses remain capable of working safely in daily practice. The work pressure that nurses experience during their normal duties could prevent them from working safely during everyday work.

Adult↗
PubMed1997

Relative exercise intensity of long-distance marching (120 km in 4 days) in 153 subjects aged 69-87 years.

The aim of this study was to determine the relative exercise intensity (oxygen uptake during the march/maximal oxygen uptake, VO2march/VO2max) during a long-distance march in subjects or over 70 years of age. Secondly, the effect of hypertension, cardiovascular and pulmonary diseases on the relative exercise intensity was evaluated. One hundred and fifty-three subjects, 97 men aged 76.7 (4.6) years and 56 women aged 72.8 (3.6) years who completed the 1993 Nijmegen day long-distance march (30 km x day(-1) on 4 consecutive days) participated in the study. Oxygen uptake (VO2) during walking at different velocities (v) was measured in a subgroup of nine men and nine women, selected randomly from the population under study. With these data, regression equations describing the relationship between VO2 and v were made. VO2march was estimated with the obtained regression equations from an average of the v(march) measured in all participants. VO2max was determined using incremental cycle ergometry in all subjects. VO2march was 13.7 (1.8) ml x kg(-1) x min(-1) in men and 15.2 (1.3) ml x kg x min(-1) in women at a mean v of 5 km x h(-1) in both sexes. This corresponded to 52% of VO2max in men and 63% in women. In both sexes subjects with cardiovascular and/or pulmonary diseases walked at a slower v and thus lower VO2march compared to subjects without these diseases. Due to the lower VO2max in subjects with these diseases there was no difference in the relative exercise intensity between the groups. A multiple linear regression analysis showed that and not age on the prevalence of hypertension, cardiovascular and/or pulmonary that VO2max was the most important predictor of the variance in self-selected v(march). This study demonstrates that these active people aged over 70 years could maintain a high relative exercise intensity during endurance walking on 4 subsequent days. Furthermore, it shows that the relative exercise intensity of marching is within the range recommended for improving fitness and reducing the risk of cardiovascular diseases. Finally, these results demonstrate that VO2max has a more important influence on performance than does age or chronic diseases in active elderly people.

Aged↗
PubMed1997

Cerebral and circulatory haemodynamics before vasovagal syncope induced by orthostatic stress.

Vasovagal syncope is usually described as a sudden and transient loss of consciousness that resolves spontaneously. Cardiocirculatory changes are well described during and before syncope. However, changes in the cerebral oxygenation are not well defined. In this study, near-infrared spectroscopy (NIRS) was used to assess the cerebral oxygenation directly during 80 degree head-up (HU) tilt. To simulate central hypovolaemia, 500 ml of blood was drawn from each of 10 healthy subjects. Oxygenation index (OI) was defined as the difference between oxy- and deoxyhaemoglobin concentration. Blood pressure, heart rate and cardiac output were monitored using a finger plethysmographic device. The protocol was divided into two stages, each consisting of a 15-min stabilization period in the supine (SUP) position, 15 min in HU position and another 10 min in SUP position. Between both stages, blood was drawn from the subject. Haemoglobin concentration and haematocrit were measured before and 30 min after withdrawal of blood. No compensatory haemodilution was observed. During HU position in the second stage, six subjects showed signs of presyncope (F) and four did not (NF). A significant difference between F and NF was found in the observation that, before fainting, the OI of F showed a steady and significant (P = 0.02) decrease (-1.4 +/- 0.5 microM min-1) compared with NF (-0.18 +/- 0.16 microM min-1). This indicates that the onset of (pre)syncope is preceded by a mismatch between oxygen demand and oxygen supply in the cerebrum. Using NIRS enabled us to monitor this mismatch and to predict the onset of a syncope before clear signs in cardiocirculatory variables were visible.

Adult↗
PubMed1997

Reference values for maximum work capacity in relation to body composition in healthy Dutch children.

Exercise performance is associated with physical development. For sick children, there is a need for parameters reflecting exercise performance, which should be easy to measure and should take their nutritional state into account. The aim of this study was to investigate the relationship between maximum work-load (Wmax) and body weight (BW) as well as fat-free mass (FFM) in healthy children performing an incremental maximum exercise test on a bicycle ergometer, and to develop reference values for Wmax corrected for nutritional state. A random sample of 158 children (77 boys and 81 girls), aged 12-18 yrs, underwent an incremental maximum exercise test on a bicycle ergometer. BW and FFM were also measured. Correlation analysis showed a significant association (p < 0.001) between BW and Wmax (boys: r = 0.82; girls: r = 0.73), and between FFM and Wmax (boys: r = 0.89; girls: r = 0.79). Two-way analysis of variance showed a significant effect of gender on variance of Wmax/BW ratio as well as Wmax/FFM ratio. The influence of age was significant for Wmax/FFM (p = 0.003), but not for Wmax/BW. The maximum workload/body weight ratio and the maximum workload/fat-free mass ratio are useful parameters of work capacity in bicycle exercise testing in children. The reference values (mean, SD, median, and percentiles) for boys and girls aged 12-18 years can be used to predict workload corrected for body composition in healthy and sick children.

Adipose Tissue↗
PubMed1995

Physiological responses to asynchronous and synchronous arm-cranking exercise.

The purpose of this study was to examine mechanical efficiency (ME) and physiological responses during asynchronous (the pedal arms oriented in opposing directions) arm-cranking exercise (AACE) and compare these responses to those obtained during synchronous (the pedal arms oriented in the same direction) arm-cranking exercise (SACE). Ten male subjects participated in the study and performed two exercise tests, one AACE and the other SACE in counter-balanced order. Each test consisted of submaximal (30, 60 and 90 W) and maximal exercise. At 30 W, gross ME was significantly lower during SACE compared to AACE, whereas at 60 W and 90 W no differences between the two types of exercise could be observed. We found that at lower power output levels the flywheel mass and its moment of inertia may have induced more body movements for compensation, which may have been more pronounced during SACE than during AACE. At higher levels of power output this flywheel masseffect was less, which explained the lack of differences in ME at these levels. Physiological responses to maximal AACE or SACE exercise were not significantly different. The results indicated that there were no differences in physiological responses to AACE and SACE exercise at higher exercise intensities. However, at lower levels of power output ME seemed to decrease, most likely as a result of the flywheel-mass effect, which was more pronounced during SACE.

Adult↗
PubMed1995

Maximal oxygen uptake in 153 elderly Dutch people (69-87 years) who participated in the 1993 Nijmegen 4-day march.

There are no studies on oxygen uptake of groups of physically active subjects aged over 70. This study describes the maximal oxygen uptake (VO2max) of 153 elderly people who completed the Nijmegen annual 4-day march (at least 30 km.day-1) in 1993. A total of 97 men with a mean age of 76.7 (SD 4.6) and 56 women with a mean age of 72.8 (SD 3.6) years participated in the study. The VO2max was determined using incremental cycle ergometry; 91 men and 49 women completed a maximal exercise test. Criteria for maximal performance were respiratory exchange ratio equal to or greater than 1.00, vertilatory equivalent for oxygen equal to or greater than 30.00 and maximal heart rate equal to or greater than (beats.min-1) 210 minus age (years). Mean maximal power output was 148.2 (SD 27.2) W and 120.4 (SD 20.5) W, mean VO2max.body mass-1 was 26.8 (SD 4.9) ml.kg-1.min-1 and 24.6 (SD 4.7) ml.kg-1.min-1, mean maximal heart rate was 152 (SD 18), and 157 (SD 14) beats.min-1 in men and women respectively. The mean VO2max.body mass-1 was about 20% higher than reported in other studies on subjects over 70 years of age. Mean maximal heart rate was about 10 beats.min-1 higher than predicted from the equation 220-age. The negative effect of chronic disease on VO2max.body mass-1 was smaller than in a sedentary reference population. The mean decline in VO2max.body mass-1 with age was 0.46 and 0.38 ml.kg-1.min-1 per year in the men and women respectively, which is the same rate as found in younger subjects. It was concluded that regular exercise might substantially increase aerobic power in the physically active elderly, even when they have chronic disease, and that it is unlikely that there is an accelerated loss of aerobic power in physically active elderly people aged over 70 year.

Aged↗
PubMed1995

The development of compensatory hypertrophy in the plantaris muscle of the rat.

The aim of this investigation was to study the time course of compensatory hypertrophy (CH) over a seven week period after its surgical induction in the lower limb of the rat. CH of the left plantaris muscle of the rat was induced by denervation of the ipsilateral gastrocnemius and soleus muscles. Muscle fibres were classified as type I, Ic, IIa and IIb. Hypertrophy of the muscle was first observed about ten days after induction of CH. All fibre types appeared to contribute to this hypertrophy. During the period between four and twenty eight days there was a marked increase in the percentage of type I fibres, mainly at the expense of type IIa, as compared with control muscles. During this CH period so called 'intermediate' Ic fibres were found, indicating fibre type transition taking place. The isometric twitch time to peak tension (TPT) of the plantaris muscle was studied in situ. The TPT of CH muscles remained the same during the experimental period of seven weeks. This might be explained by the effect of the increase in type I (slow) fibres being masked by the far larger number of fast fibres, which still accounted for approximately 79% of the total number of fibres after CH.

Aging↗
PubMed1994

Properties of the venous vascular system in the lower extremities of individuals with paraplegia.

The purpose of this study was to examine the properties of the venous vascular system in the lower extremities of individuals with long-standing paraplegia (PP). The venous volume variations (VVV), the venous capacity (VC), the venous emptying rate (VER) and the venous flow resistance (VFR) were measured in the left calf of 14 male PP and 12 male able-bodied subjects (ABS) by means of strain-gauge occlusion plethysmography. VVV and VC were significantly lower in PP compared to ABS, -45% and -50% respectively. Both groups showed a similar resting venous pressure in the calf (PP = 24.4 mmHg; ABS = 19.6 mmHg). VER was significantly lower (-60%) and hence VFR was significantly higher (+75%) in PP compared to ABS. This study demonstrates that the venous vascular properties in the legs of individuals with paraplegia have changed, i.e. a decrease in venous distensibility and capacity and an increase in venous flow resistance. This is most probably the result of vascular adaptations to inactivity and muscle atrophy rather than the effect of a non-working leg-muscle pump and sympathetic denervation.

Adult↗
PubMed1994

The relation between upper arm dimensions and maximal oxygen uptake during arm exercise.

The relationship between upper arm dimensions and maximal oxygen uptake (VO2peak) during arm exercise was investigated. Nineteen almost untrained male subjects (22 +/- 2 yrs, 183 +/- 5.5 cm, 74 +/- 7.5 kg; mean +/- SD) volunteered to take part in the study. The following anthropometrical upper arm data were obtained for each subject: upper arm circumference, biceps and triceps skinfold thickness, upper arm length. From these data the cross-sectional area of the muscles, of the muscles plus bone of the upper arm, and the upper arm muscle volume were calculated. Upper arm volume was determined by water immersion. The subjects performed arm cranking with an increasing load of 10 watt each minute (Wpeak 125 +/- 17.4 watt, VO2peak: 2.54 +/- 0.33 l/min; mean +/- SD). Multiple regression analyses showed that VO2peak could be best explained by the cross-sectional area of the muscles plus bone of the upper arm (r = 0.65, p < 0.005). Other factors did not add significantly. The variables as body mass, fatfree body mass, upper arm volume and total arm volume correlated less well with VO2peak (r < 0.5). In conclusion it is suggested to use the easily obtainable cross-sectional area of the muscles plus bone of the upper arm to standardize VO2peak of arm cranking.

Adult↗
PubMed1994

Physical work load and its assessment among the nursing staff in nursing homes.

A study was conducted to investigate the physical work load and the prevalence of musculoskeletal complaints of nurses in nursing homes. Thirty-six female subjects selected from three nursing homes in the Netherlands participated in an observational study. In addition, the total nursing staff (n = 668) was invited to take part in a questionnaire survey (response was 94%). It was noticed that almost 60% of the observed time was spent on nonpatient-related activities. Moreover, activities alternated rapidly and seldom lasted longer than 4 minutes on average. Twenty percent of the observed time was spent in "poor" work postures as defined by the Ovako Working Posture Analyzing System (Action Category 2 to 4). Activities contributing most to these poor work postures were patient care and household and preliminary tasks. Perceived exertion as scored on the Borg-CR10 scale was highest during patient-related activities. This holds also for a relative increase of heart rate. Questionnaire results showed prevalences of 41%, 35%, and 20% respectively, for back, arm/neck, and leg complaints. From this study it can be concluded that not only patient-related activities should be taken into consideration for the improvement of work postures and other potential strenuous aspects of nursing work. Household and preliminary tasks, ergonomic layout of the ward, and work pressure also deserve attention.

Adult↗
PubMed1994

Cardiac output determined by the CO2 rebreathing method during arm exercise.

Since arm exercise affects the respiratory muscles the CO2 rebreathing method for determining cardiac output (Q) has to be evaluated during arm exercise. The purpose of this study was (1) to compare three different methods of determining arterial CO2 tension (PaCO2) during arm exercise, (2) to verify the linearity of the relationship between Q and oxygen uptake (VO2) during arm exercise, and (3) to investigate whether the CO2 rebreathing method according to Collier can determine accurately Q during arm exercise. Sixty male subjects performed arm-cranking exercise at 20%, 40% and 60% of their individual maximal load. Carbon dioxide output (VCO2) was measured by gas exchange measurement, and mixed venous CO2 tension (PvCO2) was determined from the CO2 rebreathing plateau at each exercise level. PaCO2 was estimated in three different ways: (A) by the modified Bohr formula for dead space, (B) by an arterialized blood sample from the hyperaemic ear-lobe, and (C) by the end-expiratory CO2 tension. A, B, and C were used to calculate Qa, Qb and Qc, respectively. The Pearson's correlation coefficient was high (P < 0.01) among the three different ways of estimating PaCO2. The Q-VO2 relationship proved to be linear (P < 0.01). The Q-values showed a good agreement with the direct Fick measurements, and were in the same range compared to other results obtained by dye dilution, electrical impedance cardiography and the exponential CO2 rebreathing method during arm exercise. In conclusion, the CO2 rebreathing method appeared to be accurate to determine Q during submaximal arm exercise.

Adult↗
PubMed1993

Variability and interrelationships of surface EMG parameters during local muscle fatigue.

The inter- and intraindividual variability of the frequency power density spectral and surface EMG amplitude parameters and of the muscle fiber conduction velocity (MFCV) is studied in 26 healthy volunteers during fatiguing isometric ischemic intermittent exercise of the m. biceps brachii at 80% of the maximal voluntary contraction level, with a contraction rate of 30/min. No significant age effects were found. Males were significantly stronger compared with females. The higher initial SEMG amplitude and the stronger shift of the frequency power density spectrum (PDS) to lower frequencies appear to be significantly correlated with males. Fatigue induces an almost proportional compression of the SEMG frequency content. The muscle fiber conduction velocity has the highest intraindividual reproducibility (r = 0.81). Despite the definite and strong influence of the MFCV on the PDS, the shift of the PDS can not be explained by a change of MFCV alone.

Adult↗
PubMed1993

A pulmonary rehabilitation program for patients with asthma and mild chronic obstructive pulmonary diseases (COPD).

The effects of a pulmonary rehabilitation program on 44 patients with chronic obstructive pulmonary disease (COPD) were compared to a control group. The treated group was admitted to the program for a period of three months. The program consisted of several parts, such as physical training, health education, and psychological and social matters. Before participation, the patients were thoroughly examined and provided with optimal medical treatment. Both groups were assessed by means of biometrical tests and questionnaires for a period of 2 years. The rehabilitation group improved significantly in endurance, psychological parameters, and consumption of medical care. Working days increased and their way of life became more active. Smoking habits and body fat percentage decreased. Bronchial hyperreactivity, need for pulmonary drugs, and coughing and sputum production did not improve in the rehabilitation group compared to the control group. Airway obstruction, expressed as forced expiratory volume in one second, and complaints of dyspnea, allergy and hyperreactivity scores on questionnaires improved only in the short term (< 1 year), but did not improve significantly in the long term. This study shows that pulmonary rehabilitation can result in improvements in patients with asthma or COPD who have many complaints despite the fact that their pulmonary function is not severely disturbed.

Adult↗
PubMed1993

Cardiac output in paraplegic subjects at high exercise intensities.

The purpose of this investigation was to compare cardiac output (Qc) in paraplegic subjects (P) with wheelchair-confined control subjects (C) at high intensities of arm exercise. At low and moderate exercise intensity Qc was the same at a given oxygen uptake (VO2) in P and C. A group of 11 athletic male P with complete spinal-cord lesions between T6 and T12 and a group of 5 well-matched athletic male C performed maximal arm-cranking exercise and submaximal exercise at 50%, 70% and 80% of each individual's maximal power output (Wmax). Maximal VO2 (VO2max) was significantly lower, VO2max per kilogram body mass was equal and maximal heart rate (fc) was significantly higher in P compared to C. At VO2 of 1.3, 1.5 and 1.7 l.min-1, and for P 65%-90% of the VO2max, Qc was not significantly different between the groups, although, Qc in P was achieved with a significantly lower stroke volume (SV) and a significantly higher fc. Although the SV was lower in P, it followed the same pattern as SV in C during incremental exercise, i.e. an increase in SV until about 45% Wmax and thereafter a stable SV. The similar Qc at a given VO2 in both groups indicated that, even at high exercise intensities, circulation in P can be considered isokinetic with a complete compensation by fc for a lower SV.

Adult↗