Introduction: Reference values for cardiopulmonary exercise testing (CPET) parameters provide the comparative basis for answering important questions concerning the normalcy of exercise responses in patients, and significantly impacts the clinical decision-making process. Areas covered: The aim of this study was to provide an updated systematic review of the literature on reference values for CPET parameters in healthy subjects across the life span. A systematic search in MEDLINE, Embase, and PEDro databases were performed for articles describing reference values for CPET published between March 2014 and February 2019. Expert opinion: Compared to the review published in 2014, more data have been published in the last five years compared to the 35 years before. However, there is still a lot of progress to be made. Quality can be further improved by performing a power analysis, a good quality assurance of equipment and methodologies, and by validating the developed reference equation in an independent (sub)sample. Methodological quality of future studies can be further improved by measuring and reporting the level of physical activity, by reporting values for different racial groups within a cohort as well as by the exclusion of smokers in the sample studied. Normal reference ranges should be well defined in consensus statements.
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PURPOSE: To compare the responses in knee joint muscle activation patterns to different perturbations during gait in healthy subjects.SCOPE: Nine healthy participants were subjected to perturbed walking on a split-belt treadmill. Four perturbation types were applied, each at five intensities. The activations of seven muscles surrounding the knee were measured using surface EMG. The responses in muscle activation were expressed by calculating mean, peak, co-contraction (CCI) and perturbation responses (PR) values. PR captures the responses relative to unperturbed gait. Statistical parametric mapping analysis was used to compare the muscle activation patterns between conditions.RESULTS: Perturbations evoked only small responses in muscle activation, though higher perturbation intensities yielded a higher mean activation in five muscles, as well as higher PR. Different types of perturbation led to different responses in the rectus femoris, medial gastrocnemius and lateral gastrocnemius. The participants had lower CCI just before perturbation compared to the same phase of unperturbed gait.CONCLUSIONS: Healthy participants respond to different perturbations during gait with small adaptations in their knee joint muscle activation patterns. This study provides insights in how the muscles are activated to stabilize the knee when challenged. Furthermore it could guide future studies in determining aberrant muscle activation in patients with knee disorders.
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Objective: Psychophysical lift capacity tests are lifting tests in which the performance, expressed in Newtons, is divided by the perceived exertion, expressed on a Borg scale. The aim of this study was to analyse test-retest reliability of psychophysical lift capacity tests.Subjects: Patients with non-specific chronic low back pain (n=20) and healthy subjects (n=20).Methods: Psychophysical lift capacity tests were assessed during a back school intake at the Centre for Rehabilitation of the University Medical Centre Groningen. Patients on the waiting list and healthy subjects were assessed twice, with a 2-week interval between assessments. Intra-class correlation (ICC) was calculated as a measure of reliability. An ICC ≥0.75 was considered as an acceptable reliability. Limits of agreement as a measure for natural variation were calculated.Results: The psychophysical static and dynamic lift capacity tests showed good reliability (ICC ≥0.75). The limits of agreement are substantial, indicating a considerable natural variation between test-sessions for all psychophysical tests.Conclusion: The psychophysical static lift capacity and dynamic lifting capacity are reliable instruments for patients with non-specific chronic low back pain and healthy subjects. However, a substantial amount of natural variation should be taken into account between 2 test sessions when interpreting the test results clinically.
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OBJECTIVE: The prevalence of osteoarthritis (OA) increases, but the impact of the disorder on peoples' functional capacity is not known. Therefore, the objective of this study was to compare self-reported health status and functional capacity of subjects with early OA of hip and/or knee to reference data of healthy working subjects and to assess whether this capacity is sufficient to meet physical job demands.METHODS: Self-reported health status and functional capacity of 93 subjects from the Cohort Hip and Cohort Knee (CHECK) were measured using the Short-Form 36 Health Survey and 6 tests of the Work Well Systems Functional Capacity Evaluation. Results were compared with reference data from 275 healthy workers, using t-tests. To compare the functional capacity with job demands, the proportions of subjects with OA performing lower than the p(5) of reference data were calculated.RESULTS: Compared to healthy workers, the subjects (mean age 56) from CHECK at baseline reported a significantly worse physical health status, whereas the women (n = 78) also reported a worse mental health status. On the FCE female OA subjects performed significantly lower than their healthy working counterparts on all 6 tests. Male OA subjects performed lower than male workers on 3 tests. A substantial proportion of women demonstrated functional capacities that could be considered insufficient to perform jobs with low physical demands.CONCLUSIONS: Functional capacity and self-reported health of subjects with early OA of the hips and knees were worse compared to healthy ageing workers. A substantial proportion of female subjects did not meet physical job demands.
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RATIONALE: Disturbed protein metabolism may result in malnutrition. A non-invasive low cost clinical tool to measure protein metabolism is lacking. Explorative research (n=1) with a newly developed non-invasive 13C-protein breath test suggested a decrease in protein oxidation after a protein restricted diet. Now, we aimed to test the effect of protein restriction in more subjects, to assess sensitivity of the test.METHODS: In this exploratory study, 14 healthy male subjects (23±3 y) participated. Habitual intake was assessed by a 4-day food diary. Next, subjects were instructed to use a 4-day isocaloric protein restricted diet (0.25 g protein/kg bw/day). After an overnight fast, a 30 g naturally enriched 13C-milk protein test drink was consumed, followed by collection of breath samples up to 330 min. Protein oxidation was analyzed by Isotope Ratio Mass Spectrometry. 24-h urine was collected on day 4 of the habitual diet, and on every day of the 4-day protein restricted diet, to assess actual change in protein intake.RESULTS: After the protein restricted diet, 30.2%±7.7 of the 30 g 13C-milk protein was oxidized over 330 min, compared to 30.6%±6.2 (NS) after the subject’s habitual diet (1.4±0.3 g protein/kg bw/day). Within subjects, both increase and decrease in oxidation was found. During the 4-day protein restricted diet, urinary urea:creatinine ratio decreased by 56%±10, consistent with a reduction in protein intake of 44%±15 (g/day) and 53%±12 (g/kg bw/day), based on urea and food diary, respectively.CONCLUSIONS: The breath test shows variation within subjects and between diets, which could be related to the sensitivity of the test. We cannot explain the variation by the measured variables. Alternatively, our results may implicate that in some of our subjects, protein intake did not sufficiently decrease to levels that could alter protein metabolism.
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RATIONALE: Disturbed protein metabolism may result in malnutrition. A non-invasive low cost clinical tool to measure protein metabolism is lacking. Explorative research (n=1) with a newly developed non-invasive 13C-protein breath test suggested a decrease in protein oxidation after a protein restricted diet. Now, we aimed to test the effect of protein restriction in more subjects, to assess sensitivity of the test.METHODS: In this exploratory study, 14 healthy male subjects (23±3 y) participated. Habitual intake was assessed by a 4-day food diary. Next, subjects were instructed to use a 4-day isocaloric protein restricted diet (0.25 g protein/kg bw/day). After an overnight fast, a 30 g naturally enriched 13C-milk protein test drink was consumed, followed by collection of breath samples up to 330 min. Protein oxidation was analyzed by Isotope Ratio Mass Spectrometry. 24-h urine was collected on day 4 of the habitual diet, and on every day of the 4-day protein restricted diet, to assess actual change in protein intake.RESULTS: After the protein restricted diet, 30.2%±7.7 of the 30 g 13C-milk protein was oxidized over 330 min, compared to 30.6%±6.2 (NS) after the subject’s habitual diet (1.4±0.3 g protein/kg bw/day). Within subjects, both increase and decrease in oxidation was found. During the 4-day protein restricted diet, urinary urea:creatinine ratio decreased by 56%±10, consistent with a reduction in protein intake of 44%±15 (g/day) and 53%±12 (g/kg bw/day), based on urea and food diary, respectively.CONCLUSIONS: The breath test shows variation within subjects and between diets, which could be related to the sensitivity of the test. We cannot explain the variation by the measured variables. Alternatively, our results may implicate that in some of our subjects, protein intake did not sufficiently decrease to levels that could alter protein metabolism.
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Objective: Gaining too much or too little weight in pregnancy (according to Institute of Medicine (IOM) guidelines) negatively affects both mother and child, but many women find it difficult to manage their gestational weight gain (GWG). Here we describe the use of the intervention mapping protocol to design ‘Come On!’, an intervention to promote adequate GWG among healthy pregnant women. Design: We used the six steps of intervention mapping: (i) needs assessment; (ii) formulation of change objectives; (iii) selection of theory-based methods and practical strategies; (iv) development of the intervention programme; (v) development of an adoption and implementation plan; and (vi) development of an evaluation plan. A consortium of users and related professionals guided the process of development. Results: As a result of the needs assessment, two goals for the intervention were formulated: (i) helping healthy pregnant women to stay within the IOM guidelines for GWG; and (ii) getting midwives to adequately support the efforts of healthy pregnant women to gain weight within the IOM guidelines. To reach these goals, change objectives and determinants influencing the change objectives were formulated. Theories used were the Transtheoretical Model, Social Cognitive Theory and the Elaboration Likelihood Model. Practical strategies to use the theories were the foundation for the development of ‘Come On!’, a comprehensive programme that included a tailored Internet programme for pregnant women, training for midwives, an information card for midwives, and a scheduled discussion between the midwife and the pregnant woman during pregnancy. The programme was pre-tested and evaluated in an effect study.
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Healthy gestational weight gain (GWG) is associated with better pregnancy outcomes and with improved health in the later lives of women and babies. In this thesis the author describes the process of developing an intervention to help pregnant women reach a healthy GWG. The need for this intervention was derived from discussions with midwives, working in primary care in the Netherlands. In this introduction, the author describes the background of the larger project “Promoting Health Pregnancy”, of which this study is a part (1.2), the problem of unhealthy GWG (1.3-1.6) and offers a brief introduction to the theoretical framework of the study and to the subsequent chapters (1.7-1.9).
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1. An earlier study by our group revealed that the viscosity of faeces from patients with Crohn's disease is significantly lower than that of healthy subjects. This is due to low concentrations of a high-molecular-mass carbohydrate, probably of bacterial origin. The cause of this phenomenon might be the impaired barrier function of the gut mucosa. Low viscosity may allow close contact of intestinal contents (bacterial products and toxins) with the intestinal wall. This could play a role in the maintenance of the disease.2. The first aim of this study was to investigate the high-molecular-mass carbohydrate fraction, responsible for viscosity, in detail. We also tried (in a pilot study) to raise the intestinal viscosity of patients with Crohn's disease with the undegradable food additive hydroxypropylcellulose (E463), in an attempt to alleviate clinical symptoms.3. The high-molecular-mass fraction (>300 kDa) responsible for faecal viscosity was sensitive to lysozyme and contained high levels of muramic acid. It was concluded that this material consisted mainly of peptidoglycan polysaccharides and was consequently of bacterial origin. The muramic acid in material from patients with Crohn's disease was 7.5 (1.5-13.9)%, which was less than in healthy subjects [11.4 (8.5-24.1)%; P=0.0004]. Furthermore, viscosity in material from patients with Crohn's disease was found to be half [14.9 (1.0-33.6) cP] of that found in healthy subjects [35.0 (2.7-90.7) cP; P=0.004].4.A daily dose of 1 g of hydroxypropylcellulose caused an increase in faecal viscosity in patients with Crohn's disease (from 1.4 to 2.3 cP) and in healthy subjects (from 4.9 to 7.5 cP). Faecal consistency improved in patients with Crohn's disease (from watery and loose to formed) and the defecation frequency decreased from 3-4 to about 2 times a day. No changes in defecation patterns were found in healthy subjects.5. These data indicate that the high-molecular-mass fraction that is responsible for faecal viscosity is peptidoglycan. Furthermore, a daily dose of a hydroxypropylcellulose solution to increase the viscosity of the intestinal contents of patients with Crohn's disease might be beneficial. This approach merits further study.
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Purpose – Self-efficacy has often been found to play a significant role in healthy dietary behaviours. However, self-efficacy interventions most often consist of intensive interventions. The authors aim to provide more insight into the effect of brief self-efficacy interventions on healthy dietary behaviours. Design/methodology/approach – In the present article, two randomized controlled trials are described. In study 1, a brief self-efficacy intervention with multiple self-efficacy techniques integrated on a flyer is tested, and in study 2, an online brief self-efficacy intervention with a single self-efficacy technique is tested. Findings – The results show that a brief self-efficacy intervention can directly increase vegetable intake and indirectly improve compliance to a diet plan to eat healthier. Originality/value – These findings suggest that self-efficacy interventions do not always have to be intensive to change dietary behaviours and that brief self-efficacy interventions can also lead to more healthy dietary behaviours.
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