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The headbox water is the main source of bacterial contamination of paper machines. Identification of these bacterial contaminants could be an asset in developing specific control methods. An amplified ribosomal DNA restriction analysis (ARDRA) was carried out to characterize the bacterial communities associated with the headbox water of a paper machine in a Canadian mill in February and July 2006. Eight bacterial genera were identified as the main colonizers present in the headbox water. The genus Meiothermus appeared to be the dominant bacterial group in the Canadian paper machine. Some variation was observed between the February and July clone libraries. Bacterial genera such as Chelatococcus and Hydrogenophilus were only detected in February or in July, respectively. Furthermore, the proportion of Tepidimonas clones in the libraries was higher in July than in February. The metabolic profile of the February and July communities, determined using Biolog EcoPlates, also suggested that temporal variation occurred within the bacterial populations that colonized the headbox of the paper machine.

Many position stands and review papers have refuted the myths associated with resistance training (RT) in children and adolescents. With proper training methods, RT for children and adolescents can be relatively safe and improve overall health. The objective of this position paper and review is to highlight research and provide recommendations in aspects of RT that have not been extensively reported in the pediatric literature. In addition to the well-documented increases in muscular strength and endurance, RT has been used to improve function in pediatric patients with cystic fibrosis and cerebral palsy, as well as pediatric burn victims. Increases in children's muscular strength have been attributed primarily to neurological adaptations due to the disproportionately higher increase in muscle strength than in muscle size. Although most studies using anthropometric measures have not shown significant muscle hypertrophy in children, more sensitive measures such as magnetic resonance imaging and ultrasound have suggested hypertrophy may occur. There is no minimum age for RT for children. However, the training and instruction must be appropriate for children and adolescents, involving a proper warm-up, cool-down, and appropriate choice of exercises. It is recommended that low- to moderate-intensity resistance exercise should be done 2-3 times/week on non-consecutive days, with 1-2 sets initially, progressing to 4 sets of 8-15 repetitions for 8-12 exercises. These exercises can include more advanced movements such as Olympic-style lifting, plyometrics, and balance training, which can enhance strength, power, co-ordination, and balance. However, specific guidelines for these more advanced techniques need to be established for youth. In conclusion, an RT program that is within a child's or adolescent's capacity and involves gradual progression under qualified instruction and supervision with appropriately sized equipment can involve more advanced or intense RT exercises, which can lead to functional (i.e., muscular strength, endurance, power, balance, and co-ordination) and health benefits.

We examined the microbial community structure and quantified the levels of the filamentous bulking organism Thiothrix eikelboomii in samples of activated sludge mixed liquor suspended solids (MLSS) from Canadian pulp and paper mills. Libraries of chaperonin 60 (cpn60) gene sequences were prepared from MLSS total microbial community DNA and each was compared with cpnDB, a reference database of cpn60 sequences (http://cpndb.cbr.nrc.ca) for assignment of taxonomic identities. Sequences similar to but distinct from the type strain of T. eikelboomii AP3 (ATCC 49788T) (approximately 89% identity over 555 bp) were recovered at high frequency from a mill sample that was experiencing bulking problems at the time of sample collection, which corresponded to microscopic observations using fluorescent in situ hybridization with commercially available 16S rDNA-based probes. We enumerated this strain in five mill-derived MLSS samples using real-time quantitative PCR (qPCR) and found that two samples had high levels of the bulking strain (>1012 genomes/g MLSS) and two contained lower but detectable levels of this organism. None of the mill samples contained cpn60 sequences that were identical to the type strain of T. eikelboomii. This technique shows promise for monitoring pulp and paper mill wastewater treatment systems by detecting and enumerating this strain of T. eikelboomii, which may be specific to pulp and paper mill wastewater treatment systems.

Resin acids, a group of diterpenoid carboxylic acids present mainly in softwood species, are present in many pulp mill effluents and toxic to fish in recipient waters. They are considered to be readily biodegradable. However, their removal across biological treatment systems has been shown to vary. Recent studies indicate that natural resin acids and transformation products may accumulate in sediments and pose acute and chronic toxicity to fish. Several resin acid biotransformation compounds have also been shown to bioaccumulate and to be more resistant to biodegradation than the original material. Until recently, the microbiology of resin-acid degradation has received only scant attention. Although wood-inhabiting fungi have been shown to decrease the level of resin present in wood, there is no conclusive evidence that fungi can completely degrade these compounds. In contrast, a number of bacterial isolates have recently been described which are able to utilize dehydroabietic or isopimaric acids as their sole carbon source. There appears to be an unusually high degree of substrate specificity with respect of the utilization of abietane congeners and the presence of substituents. Pimaranes do not appear to be attacked to the same extent as the abietanes. This paper reviews the occurrence, chemistry, toxicity, and biodegradation of resin acids in relation to the biological treatment of pulp and paper mill effluents.

Historically, the constructs of inclusion, diversity, equity, and access (IDEA) have not been sufficiently considered or included in population health nutrition research and practice. Consequently, current nutrition assessment benchmarks and knowledge translation tools may not accurately or adequately reflect diversity in the Canadian population or produce meaningful dietary guidance. The purpose of this current opinion paper is to introduce the population health nutrition research and practice framework and explore the current application of IDEA within this framework. Recommendations are offered to incorporate the constructs of IDEA along the continuum of future nutrition research and services to improve population nutritional health., Competing Interests: The authors declare there are no competing interests.

Integrated knowledge translation (IKT) and community-based participatory research (CBPR) are recognized as effective approaches when Indigenous and non-Indigenous partners work together to focus on a common goal. The "Learning Circles: Local Healthy Food to School" (LC:LHF2S) study supported the development and implementation of Learning Circles (LC) in 4 Canadian Indigenous communities with the goal of improving local, community-based healthy food systems. Critical to the research process were annual gatherings (AG) where diverse stakeholders (researchers, Indigenous community members, and partners) visited each community to share knowledge, experiences, and provide support in the research process. Using a qualitative, descriptive method, this paper explores how the AG supported IKT across partners. Yearly interviews involving 19 total participants (with some participating multiple times across the 4 gatherings) elicited their AG experiences in supporting local LC:LHF2S. Three themes with multiple sub-themes were identified: (a) setting the stage for IKT (importance of in-person gatherings for building relationships across partners, learning from each other), (b) enabling meaningful engagement (aligning research with Indigenous values, addressing tensions and building trust over time, ensuring flexibility, and Indigenous involvement and leadership), and (c) supporting food system action at the local level (building local community engagement and understanding, and integrating support for implementation and scale-up of LC). This paper provides useful and practical examples of the principles of Indigenous-engaged IKT and CBPR in action in healthy, local, and traditional food initiatives. AG are a valuable IKT strategy to contribute to positive, transformative change and ethical research practice within Indigenous communities.

Guidance from Health Canada to limit highly processed foods (HPF) seeks to ensure that Canadians remain within intake recommendations for nutrients of concern. However, HPF can contribute to dietary requirements of specific populations. The Canadian Nutrition Society and Institute for the Advancement of Food and Nutritional Sciences convened speakers for a Food for Health workshop in 2021 to provide evidence and perspectives from government, industry, and healthcare on reasons for advocating limits and potential unintended consequences of limiting HPF, and implications and necessity of HPF in clinical settings. This paper discusses advantages and disadvantages of HPF explored at this workshop.

Indigenous communities in Canada are concerned about the health of their youth and the reclamation of traditional food-related skills amongst their people. Food sovereignty has an integral role in food and nutrition security, and the path to Indigenous self-determination. Learning Circles: Local Healthy Food to School (LC:LHF2S) was a community engagement model that aimed to enhance access to local, healthy, and traditional foods for youth. In each of four First Nations communities, a Learning Circle Evaluation Facilitator worked to plan and implement activities, build on community strengths, and promote partnerships. This paper describes how the model was perceived to support food sovereignty. Data included interviews, process reporting, and school surveys, and was analyzed according to pillars effective for the development of food sovereignty in Indigenous communities. Goals set by two communities incorporated food sovereignty principles, and in each community capacity-building work furthered the development of a more autonomous food system. There were many examples of a transition to greater food sovereignty, local food production, and consumption. Indigenous governance was an important theme and was influential in a community's success. The model appears to be an adaptable strategy to support the development of food sovereignty in First Nations communities. Novelty : LC:LHF2S was a community engagement model that aimed to enhance access to local, healthy, and traditional foods for youth. The model is an adaptable strategy to support the development of food sovereignty in First Nations communities. There were many examples of a transition to greater food sovereignty, local food production, and consumption.

Evidence-based guidelines represent the highest level of scientific evidence to identify best practices for clinical/public health. However, the availability of guidelines do not guarantee their use, targeted knowledge translation strategies and tools are necessary to help promote uptake. Following publication of the 2019 Canadian Guideline for Physical Activity throughout Pregnancy , the Get Active Questionnaire for Pregnancy , and an associated Health Care Provider Consultation Form for Prenatal Physical Activity were developed to promote guideline adoption and use amongst pregnant individuals and health care providers. This paper describes the process of developing these tools. First, a survey was administered to qualified exercise professionals to identify the barriers and facilitators in using existing prenatal exercise screening tools. A Working Group of researchers and stakeholders then convened to develop an evidence-informed exercise pre-participation screening tool for pregnant individuals, building from previous tool and survey findings. Finally, end-user feedback was solicited through a survey and key informant interviews to ensure tools are feasible and acceptable to use in practice. The uptake and use of these documents by pregnant individuals, exercise, and health care professionals will be assessed in future studies. Novelty: Evidence supports the safety/benefits of exercise for most pregnant individuals; however, exercise is not recommended for a small number of individuals with specific medical conditions. The Get Active Questionnaire for Pregnancy and Health Care Provider Consultation Form for Physical Activity during Pregnancy identify individuals where prenatal exercise may pose a risk, while reducing barriers to physical activity participation for the majority of pregnant individuals.

After over seven decades of neuroscience research, it is now well established that γ-aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the brain. In this paper dedicated to Krešimir Krnjević (1927-2021), a pioneer and leader in neuroscience, we briefly highlight the fundamental contributions he made in identifying GABA as an inhibitory neurotransmitter in the brain and our personal interactions with him. Of note, between 1972 and 1978 Dr. Krnjević was a highly reputed Chief Editor of the Canadian Journal of Physiology and Pharmacology .

The ongoing coronavirus disease 2019 (COVID-19) pandemic is a rapidly evolving situation. New discoveries about COVID-19 and its causative virus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), continue to deepen the understanding of this novel disease. As there is currently no COVID-19 specific treatment, isolation is the most effective method to prevent transmission. Moreover, development of a safe and effective COVID-19 vaccine will be instrumental in reinstating pre-COVID-19 conditions. As of 31 July 2020, there are at least 139 vaccine candidates from around the globe in preclinical evaluation, with another 26 undergoing clinical evaluation. This paper aims to review the basics of COVID-19, including epidemiology, basic biology of SARS-CoV-2, and transmission. We also review COVID-19 vaccine development, including animal models, platforms under development, and vaccine development in Canada.

Establishing a step-by-step process that provides practitioners with a blueprint for translating movement guidelines into action stands to optimize the investment in guideline development, improve guideline promotion and uptake, and ultimately enhance population health. The purpose of this paper is to describe how the Knowledge-to-Action framework and integrated knowledge translation were operationalized to systematically inform our knowledge translation (KT) efforts for the Canadian 24-Hour Movement Guidelines for Adults aged 18-64 years and Adults aged 65 years or older. In October 2018, the need for a KT Process, operating in tandem with the Guideline Development Process, led to the establishment of a KT team with a specific structure and terms of reference. The KT team collaboratively agreed on decision-making principles prior to selecting target audiences to focus their efforts. We undertook formative research to assess the local context and determinants of guideline dissemination and implementation efforts among target audiences. Plans for the subsequent steps and research are outlined. We highlight recommendations and lessons learned for applying the process in other settings. Novelty We outline a collaborative and systematic process and research program for the knowledge translation of movement guidelines. This paper provides an innovative and replicable blueprint to optimize future movement guideline knowledge translation efforts.

Adequate calcium intake and supply of vitamin D during childhood play important roles in ensuring adequate bone mass gain to achieve optimal peak bone mass. The Healthy Immigrant Children study employed a mixed-method cross-sectional study design to characterize the health and nutritional status of 300 immigrant and refugee children aged 3-13 years who had been in Canada for less than 5 years. This paper presents bone mineral content and vitamin D status data along with qualitative data that deepen the understanding of newcomer bone health status. A significantly higher percentage of refugee children (72.3%) had insufficient (<50 nmol/L) or deficient (<30 nmol/L) serum vitamin D compared with immigrants (53.2%). Vitamin D deficiency was most common among ethnic minority girls. Newcomer children with higher intakes of vitamin D, younger newcomer children, and those from western Europe or the United States had higher serum vitamin D levels. Immigrants had significantly higher mean total body bone mineral content compared with refugees. Total body fat, serum vitamin D, calcium intake, height, height by calcium intake, total body fat by calcium intake, and total body fat by height predicted total body bone mineral content levels. Vitamin D deficiency among newcomer children may be related to lack of knowledge regarding children's vitamin D requirements in the Canadian environment, dietary habits established in country of origin, low income that limits healthy dietary choices, and lifestyle habits that limit exposure to sunlight. Results suggest a need to screen newcomer children and pregnant women for vitamin D deficiency and support early intervention.

The purpose of this paper is to critique how the promotion of physical activity (PA) is communicated and offer evidence-based alternative framings to encourage PA in youth. We argue that PA promotion messaging should not be tied to outcomes that focus on changing physical appearance, preventing or treating diseases, or sport performance or competition. From a public health perspective, we suggest that PA should instead focus on campaigns, policies, and programs that tie PA to enjoyment, wellbeing, and play.

This Horizons is part of a series that identifies key, forward-thinking research questions and challenges that need to be addressed. Specifically, this Horizons paper discusses research in nutritional supplements and nutraceuticals for health, physical activity, and performance, and is the product of a discussion by an expert panel that took place in January 2018 prior to the Canadian Nutrition Society Thematic Conference "Advances in Sport Nutrition from Daily Living to High Performance Sport". The objective of this Horizons paper was to identify core considerations for future studies for this research area, and how scientists can be leaders in the field to ensure the best quality science is available for decision makers. It is strongly recommended that the various elements highlighted throughout this Horizons paper will increase the awareness of the significant before-, during-, and after-research due-diligence required to produce research of the highest quality. While it is recognized that many scientists will not be able to meet all of these aspects, it is nonetheless important to consider the points outlined and to recognize that those elements that are not met in studies may be significant limitations. Highlights Research questions that are hypothesis-driven are the strongest, and when combined with careful planning of the study, the result will often be of the best quality. Studies with a strong experimental design help discern between evidence-based findings and those that have not been substantiated.

Epigenetics is revealing how "nature is nurtured", with environmental factors such as nutrition, environmental neurotoxicants, and psychological stress influencing DNA expression. In this current opinion paper, we argue that understanding the dynamic interplay between the genome acquired at conception and environmental exposures throughout life requires pregnancy and birth cohorts, and that greater Canadian national commitment to the infrastructure needed for sustaining such cohorts is warranted. We present a framework that is now being implemented in Alberta.

The purpose of this paper was to report the physical activity and health outcomes results from the Physical Activity Counselling (PAC) trial. Patients (n = 120, mean age 47.3 ± 11.1 years, 69.2% female) who reported less than 150 min of physical activity per week were recruited from a large community-based Canadian primary care practice. After receiving brief physical activity counselling from their provider, they were randomized to receive 6 additional patient-centered counselling sessions over 3 months from a physical activity counsellor (intensive-counselling group; n = 61), or no further intervention (brief-counselling group; n = 59). Physical activity (self-reported and accelerometer) was measured every 6 weeks up to 25 weeks (12 weeks postintervention). Quality of life was also assessed, and physical and metabolic outcomes were evaluated in a randomly selected subset of patients (33%). In the intent-to-treat analyses of covariance, the intensive-counselling group self-reported significantly higher levels of physical activity at 6 weeks (p = 0.009) and 13 weeks (p = 0.01). There were no differences in self-reported physical activity between the groups after the intervention in the follow-up period, nor was there any increase in accelerometer-measured physical activity. Finally, the intensive-counselling patients showed greater decreases in percent body fat and total fat mass from 13 weeks to 25 weeks. Results for physical activity depended on the method used, with positive short-term results with self-report and no effects with the accelerometers. Between-group differences were found for body composition in that the intensive-counselling patients decreased more. A multisite randomized controlled trial with a longer intensive intervention and follow-up is warranted.

The paper briefly reviews the status and trends in physical activity, physical inactivity, and overweight/obesity in Canada; discusses the consequences of these trends; examines evidence that our frame of reference with respect to physical activity and obesity is changing; promotes the importance of getting "back to the basics" as a strategy for enhancing childhood physical activity; and provides suggestions for future research in this area. In addressing these topics, the paper explores and contrasts the lifestyles and characteristics of Old Order Amish and Old Order Mennonite children with children exposed to contemporary modern living. This exploration is used as a model to learn from traditional lifestyles, which were comparatively active and resistant to obesity. The fitness characteristics and physical activity levels of traditional and contemporary groups are compared and demonstrate significant differences among groups. This evidence may provide important insight for informing future physical activity recommendations. Idiosyncrasies of performing research on these traditional-living groups are also provided.

Some cultural groups provide a glimpse at the past because they preserve or adhere to traditional behaviours and (or) living conditions. This brief introduction outlines a series of papers presented at the Canadian Society for Exercise Physiology Conference that used this model to explore changes in the physical activity behaviour of children over time.

The accurate measurement of habitual physical activity is fundamental to the study of the relationship between physical activity and health. However, many physical activity measurement techniques produce variables accurate to only the day level, such as total energy expenditure via self-report questionnaire, pedometer step counts, or accelerometer measurements of minutes of moderate to vigorous physical activity. Monitoring technologies providing more detailed information on physical activity and inactivity behaviour can now be used to explore the relationships between health and movement frequency, intensity, and duration more comprehensively. This paper explores the activity-inactivity profile that can be acquired through objective monitoring, with a focus on accelerometry. Using previously collected objective data, a detailed physical activity profile is presented and case study examples of data utilization and interpretation are provided. The rich detail captured through comprehensive profiling creates new surveillance and study possibilities and could possibly inform new physical activity guidelines. Data are presented in various formats to demonstrate the dangers of misinterpretation when monitoring population adherence to Canada's physical activity guidelines. Recommendations for physical activity-inactivity profiling are provided and future research needs identified.

This paper provides a brief overview of the epidemiological data regarding Canadians with physical disabilities, with a particular emphasis on health status. A literature review is then presented, focusing on activity levels and the physiological and health-related quality of life benefits of activity for people with four different physical disabilities (arthritis, fibromyalgia, spinal cord injury, and multiple sclerosis). The unique physical activity barriers faced by people with physical disabilities are discussed. The paper concludes with recommendations for the development of a physical activity guide for Canadians with physical disabilities.

The current low level of physical activity among Canadians is a dominant public health concern. Accordingly, a clear understanding of physical activity patterns and trends is of paramount importance. Irregularities in monitoring, analysis, and reporting procedures create potential confusion among researchers, policy-makers, and the public alike. The purpose of this paper is to consolidate reported findings and provide a critical assessment of the physical activity surveillance procedures, analytical practices, and reporting protocols currently employed in Canada to provide insights for accurate and consistent interpretation of data, as well as recommendations for future surveillance efforts.

The purpose of this paper is to examine the reach of different versions of Canada's physical activity guide (CPAG) and their impacts, including immediate effects (awareness, knowledge, beliefs, future intention to be active, first steps towards behavioural change) and population levels of physical activity. The analysis is based on eligible adults aged 18 years and older (n = 8892) included in the 2003 Physical Activity Monitor (PAM) survey. The 2003 PAM was a cross-sectional, telephone interview of a representative population sample. Secular trends of Canadians aged 12 years and older were examined, using representative samples from the National Population Health and Canadian Community Health Surveys. Unprompted recall of any guidelines for physical activity was very low (4%), whereas prompted recall of the CPAG was higher (37%). Unprompted and prompted recall were higher among women and high-income earners, and increased with level of education. Behaviours associated with "seeking information" and "initiating action" were associated with unprompted and prompted recall. Beliefs about the benefits of physical activity and intention to be active were also associated with prompted recall. Unprompted CPAG recall, knowledge about the amount of activity required to meet the CPAG, intention to be active, "seeking information", and "initiating action" were associated with being "sufficiently active". The CPAG is an appropriate set of public health guidelines or recommendations around physical activity. The low unprompted recall rate points to the need for a coordinated, well-funded approach to communication of these guidelines, involving governmental and non-governmental partners and intermediaries in municipalities, schools, workplaces, and the recreational, public health, and health-care systems.

Canadian public health messages relating to physical activity have historically focused on the prescription of purposeful exercise, most often assessing leisure-time physical activity (LTPA). Although LTPA contributes to total energy expenditure (TEE), a large part of the day remains neglected unless one also considers the energy expended outside of purposeful exercise. This paper reviews the potential impact of incidental (non-exercise or non-purposeful) physical activity and lifestyle-embedded activities (chores and incidental walking) upon TEE and indicators of health. Given that incidental movement occurs sporadically throughout the day, this form of energy expenditure is perhaps most vulnerable to increasingly ubiquitous mechanization and automation. The paper also explores the relationship of physical inactivity, including sleep, to physical activity, TEE, and health outcomes. Suggestions are provided for a more comprehensive physical activity recommendation that includes all components of TEE. Objective physical activity monitors with time stamps are considered as a better means to capture and examine human movements over the entire day.

Physical activity guidelines offer evidence-based behavioural benchmarks that relate to reduced risk of morbidity and mortality if people adhere to them. Essentially, the guidelines tell people what to do, but not why and how they should do it. Thus, to motivate adherence, messages that translate guidelines should convey not only how much physical activity one should attempt and why it is recommended, but also how to achieve such a recommendation. Canada's physical activity guides exemplify how guidelines can be translated. This paper (i) provides a brief overview of the challenges encountered in creating the existing guides and (ii) highlights important practical issues and empirical evidence that should be considered in the future when translating guidelines into messages and disseminating these messages. We draw on the successes of past efforts to translate the goals of physical activity guidelines and on recent literature on messages and media campaigns to make recommendations. Information to motivate people to move toward the goals in physical activity guidelines should be translated into a set of messages that are informative, thought provoking, and persuasive. These messages should be disseminated to the public via a multi-phase social-marketing campaign that is carefully planned and thoroughly evaluated.

This historical background paper chronicles the major events leading to the development of Canada's physical activity guides (for children, youth, adults, and older adults). The paper outlines the process and the steps used, including information (where applicable) regarding national partners, project administration, Health Canada communications, product development, endorsement, distribution and implementation, collateral activities, media relations and evaluation framework. Brief summaries of the science that led to the recommended guidelines are included. The paper also summarizes the various physical activity guide assessment and evaluation projects and their findings, particularly as they relate to research carried out on Canada's physical activity guides for children and youth (and the associated support resources).

The aim of this review is to provide a scientific update on evidence related to the biological and psycho-social health benefits of physical activity in school-aged children and youth. To accomplish this aim, the first part of the paper reviews existing physical activity guidelines for school-aged children and youth, with an emphasis placed on how Canada's guidelines compare and contrast with those of other countries and organizations. The paper then provides an overview of physical activity levels of Canadian children and youth, which indicates that few Canadian youngsters meet current physical activity recommendations. The next section of the paper summarizes the literature that informs how much physical activity is required to promote health and well-being in children and youth. The paper then provides suggestions on modifications that could be made to Canada's physical activity guidelines for children and youth. Specifically, consideration should be given to setting both minimal (>/=60 min/d) and optimal (up to several hours per day) physical activity targets. The final section identifies future research needs. In this section, a need is noted for comprehensive dose-response studies of physical activity and health in the paediatric age group.

This article summarizes the main findings from the papers included in this journal supplement. It consolidates the evidence currently available to inform and advance the development of physical activity guidelines for Canadians, and it highlights the specific needs of various population subgroups. The challenges of translating guideline information into effective and persuasive physical activity messages, of campaigns to disseminate messages and of related evaluations are underlined. Recommendations on how to proceed are based on the evidence base provided by this series of papers; the immediate next steps mandated by this initiative are outlined and priorities for future research are indicated.

The Canadian Society for Exercise Physiology (CSEP), in partnership with Health Canada and others, released Canada's first physical activity guide for adults in 1998, with specific versions for older adults in 1999 and for children and youth in 2002. Research in the physical activity sciences (e.g., basic science, behavioural assessment, dose-response relationships, epidemiology, health messaging, physical activity measurement) has advanced rapidly since these publications. A detailed review of relevant current research is thus required, to assess whether the existing guidelines and resulting guides need revision or renewal. This introductory paper provides a brief chronology of events leading to the preparation of this journal supplement, including a statement of purpose and an overview of organization and content. A brief discussion of the purpose of the physical activity guidelines and guides, intended biological, psychological, and behavioural outcomes, and the way in which guidelines relate to on-going measurement and surveillance is provided as a context for the papers that follow.

This paper summarizes available information on patterns of physical activity, their determinants and consequences, and the results of various interventions designed to increase the physical activity of Aboriginal peoples in Canada and the United States. There is a paucity of national data on this issue for Aboriginal peoples. The most recent data, from the First Nations Regional Longitudinal Health Survey of 2002-2003, indicate that 21% of adults (27% of men, 15% of women) were engaging in at least 30 min of moderate to vigorous physical activity on 4 d/week or more. The present paper highlights the unique challenges this group faces, underlining the need to integrate collective knowledge regarding how much physical activity is required for Aboriginal Canadians, and how this activity should be accomplished, to promote and maintain health. Efforts are currently underway to tailor Canada's physical activity guide for First Nations, Inuit, and Métis. Future research among Aboriginal groups should examine the minimal and optimal levels of physical activity required to achieve health benefits.

Chronic obstructive pulmonary disease (COPD) is one of the leading causes of morbidity and mortality in Canada and elsewhere. It affects 5% of all adult Canadians and is the fourth leading cause of death. Interestingly, the leading causes of hospitalizations and mortality among COPD patients are cardiovascular events. In the Lung Health Study, over 5 800 patients with mild to moderate COPD were studied. Forty-two to 48% of all hospitalizations that occurred over the study's 5-year follow-up period were related to cardiovascular complications. Various population-based studies suggest that independent of smoking, age, and gender, COPD increases the risk of cardiovascular morbidity and mortality twofold. Alarmingly, some bronchodilators, which are commonly used to treat symptoms in COPD, may increase the risk of cardiovascular morbidity and even mortality among COPD patients. In this paper, we discuss the epidemiologic evidence linking COPD and cardiovascular events as well as the potential mechanism(s) which may be responsible for this association.

Although changes in the soleus H-reflex (an electrical analog of the tendon jerk) with age have been examined in a number of studies, some controversy remains. Also, the effect of age on inhibitory reflexes has received little attention. The purpose of this paper was to examine some excitatory and inhibitory reflexes systematically in healthy human subjects having a wide range of ages. We confirmed that both the maximum H-reflex (Hmax) and the maximum M-wave (Mmax) (from direct stimulation of motor axons) decrease gradually with age. The decrease in Hmax was larger so the Hmax/Mmax ratio decreased dramatically with age. Interestingly, the modulation of the H-reflex during walking was essentially the same at all ages, suggesting that the pathways that modulate the H-reflex amplitude during walking are relatively well preserved during the aging process. We showed for the first time that the short-latency, reciprocal inhibitory pathways from the common peroneal nerve to soleus muscle and from the tibial nerve to the tibialis anterior muscle also decreased with age, when measured as a depression of ongoing voluntary activity. These results suggest that there may be a general decrease in excitability of spinal pathways with age. Thus, the use of age-matched controls is particularly important in assessing abnormalities resulting from disorders that occur primarily in the elderly.

This paper describes the extent of the hazardous and toxic chemical waste problems in Canada and discusses the management, treatment, and disposal methods commonly used in North America and Europe. The treatment and disposal techniques covered are biological, physical-chemical, incineration technologies, and secure land disposal. Some of the available and emerging technologies for destruction of polychlorinated biphenyls are also described.