Seasonal Variations in Health-Related Human Physical Activity

Investigating seasonal changes in factors associated with COVID-19 concerns: Results from a serial cross-sectional survey study in Germany between 2020 and 2023

Objective

COVID-19 risk perceptions are discussed to be volatile and have been shown to be connected to the adoption of preventive public health behaviors. This study aimed to investigate changes in COVID-19 concerns and influencing factors as a function of season among the German public.

Methods

Sixty-three waves of cross-sectional telephone surveys with German participants aged 14 years and older conducted at least monthly between June 2020 and April 2023 provided the data basis (N = 63,471). After pooling participants of different waves by season (spring, summer, fall, winter), data were analyzed with regard to changes in physical health, mental health, economic, and social COVID-19 concerns. Individual characteristics (e.g., age), COVID-19 behavior (e.g., hygiene practices), and related perceptions (e.g., controllability of risk) were considered as predictors of composite concerns in different seasons.

Results

Results showed a higher between-seasons than within-seasons variability in concerns, with rises in physical and mental health and social concerns during fall. Multivariate regressions revealed being female, lower education, adopting protective measures, and higher perceived probability of infection in both public and private settings to be consistent predictors of higher COVID-19 concerns. Coefficients of these predictors remained comparatively stable over seasons and years.

Conclusion

Results indicate re-occurring changes in concerns during a prolonged crisis, with distinct characteristics being consistently associated with higher reported concerns. To ensure the application of protective measures, communicators should consider that risk perceptions are subject to fluctuations, but that certain groups of individuals tend to develop them and therefore deserve particular focus.

The relationship of daily physical activity and sleep in adults: variations by age, sex, and race

Prior work suggests physical activity (PA) is related to quantity and quality of sleep. Questions remain regarding directionality, and whether relationships vary by age, sex, and race. We examined daily bidirectional associations between PA and sleep over one week. Participants were 427 adults from the MIDUS Biomarker study, with a mean age of 54.21 ± 11.67 (61% female, 30% non-white). PA (total activity) and sleep (total sleep time; TST and waking after sleep onset; WASO) were measured with an ActiWatch 64. Multilevel mixed-effects models showed differences in the relationships between PA and sleep by age, race, and sex. Following a day with increased PA, younger and nonwhite participants had significantly shorter TST. Days with higher PA were also associated with less WASO for younger participants. Bidirectional effects also emerged; following a night with shorter TST, men, not women, engaged in less next-day PA. Like other studies of daily PA and sleep, effect sizes were small. Future studies should assess potential mechanisms that could explain these demographic differences.

Mental and physical health and well-being of canadian employees who were working from home during the COVID-19 pandemic

BACKGROUND

The COVID-19 pandemic has drastically changed various aspects of our lives, including how we work. Since the start of the pandemic, numerous organizations in Canada have mandated their employees to work from home (WFH) on a full-time basis. The rapid rise in the number of remote workers and the possibility for WFH continuing in the future signifies the importance of understanding the health and well-being of employees working from home over the course of the pandemic in Canada. We present the findings of two surveys (initial and 6-month follow-up) to examine the health and well-being of WFH employees during the COVID-19 pandemic in Canada. We analyzed the changes in mental and physical health and well-being of employees who were working from home between two time points during the pandemic.

METHODS

Initial survey was completed between October 2020 and December 2020 (n = 1617); follow-up survey was completed between May 2021 and June 2021 (n = 382). We calculated the frequencies for survey questions involving demographics, WFH preferences, workstation setup training, employment situation, provision of hardware technologies, provision and usage of software technologies, and organization's return to work plan. We conducted Wilcoxon signed-rank tests to analyze the within-individual changes in mental and physical health and well-being of the 382 respondents who completed both the initial and follow-up surveys.

RESULTS

Our analyses showed significant changes in various aspects of employee mental and physical health and well-being. Burnout, stress, general mental health, and job insecurity levels significantly decreased between the two time periods. Work-related sedentary behaviour reduced over time; however, the average proportion of time spent sitting during work hours was more than 80% in both surveys. Employees received more help and feedback from their colleagues and experienced a better sense of community with their co-workers over time.

CONCLUSION

The findings can inform workers and organizations on the changes in mental and physical health and well-being of employees working from home during the pandemic. By understanding the changes in worker health and well-being, employers can develop effective strategies and implement policies that help protect employees' health and well-being.

Global Changes in Child and Adolescent Physical Activity During the COVID-19 Pandemic: A Systematic Review and Meta-analysis

IMPORTANCE

Numerous physical distancing measures were implemented to mitigate the spread of the COVID-19 virus, which could have negatively affected child and adolescent physical activity levels.

OBJECTIVES

To conduct a systematic review and meta-analysis of the literature that used validated measures to document changes in child and adolescent physical activity during the COVID-19 pandemic and to estimate whether changes in physical activity differed between participant-level, contextual, and methodological moderators.

DATA SOURCES

PubMed, PsycInfo, SPORTDiscus, Web of Science, Scopus, CINAHL, and MEDLINE were searched (from January 1, 2020, to January 1, 2022). A total of 1085 nonduplicate records were retrieved.

STUDY SELECTION

Studies were included if they reported (1) changes in the duration of physical activity at any intensity for children or adolescents (age ≤18 years) comparing before and during the COVID-19 pandemic using validated physical activity measurement tools and were (2) from general population samples, (3) peer-reviewed, and (4) published in English.

DATA EXTRACTION AND SYNTHESIS

A total of 126 articles underwent full-text review. Data were analyzed using a random-effects meta-analysis, which was conducted in January 2022.

MAIN OUTCOMES AND MEASURES

Change in the duration of engagement in physical activity at any intensity comparing before and during COVID-19.

RESULTS

Twenty-two studies including 46 independent samples and 79 effect sizes from 14 216 participants (median age, 10.5 years; range, 3-18 years) were included. The percentage change in the duration of engagement in total daily physical activity from before to during COVID-19 was -20% (90% CI, -34% to -4%). Moderation analyses revealed that changes were larger for higher-intensity activities (-32%; 90% CI, -44% to -16%), corresponding to a 17-minute reduction in children's daily moderate-to-vigorous physical activity levels. The reduction in physical activity was also larger for samples located at higher latitudes (37%; 90% CI, -1% to 89%) and for studies with a longer duration between physical activity assessments (25%; 90% CI, -0.5% to 58%).

CONCLUSIONS AND RELEVANCE

Children and adolescents have experienced measurable reductions in physical activity during the COVID-19 pandemic. Findings underscore the need to provide bolstered access to support and resources related to physical activity to ensure good health and social functioning among children and adolescents during pandemic recovery efforts.

Impacts of ambient temperature and seasonal changes on sports injuries in Madrid, Spain: a time-series regression analysis

Objectives

Recreational physical activity is an integral part of our society, and the injuries caused by sports activities are a concern for public health. We studied the effect of outdoor ambient temperature on hospital emergency department visits caused by sports injuries in Madrid, Spain, and accounted for its seasonal changes.

Methods

We used a time-series design. Data was analysed with quasi-Poisson regression models. We calculated the proportion of emergency visits attributable to seasonal changes before and after adjusting for daily ambient temperature. We modelled the association between emergency visits and temperature using distributed lag non-linear models.

Results

The proportion of emergency visits attributable to seasonal changes was 24.1% and decreased to 7.6% after adjusting for temperature. We found a high risk of emergency visits associated with cold and hot temperatures, whereas the risk was higher for heat.

Conclusion

Sports and recreational physical activity injuries are not rare events; therefore, appropriate healthcare decisions should consider the impact of outdoor ambient temperature and seasonal changes.

Association of morningness-eveningness preference with physical activity during the COVID-19 pandemic social distancing: a cross-sectional survey in Brazil

Social distancing (SDIST) to contain COVID-19 pandemic spread implies reduced sunlight exposure and social daily life, which delay the circadian system and increase eveningness preference. The regular practice of physical activity (PA) is a time cue that decreased during SDIST. However, it is unknown if decreased PA may be associated with increase of eveningness preference. This study aimed to investigate if PA changes might be associated with changes in the morningness-eveningness preference of individuals practicing SDIST in Brazil. For this, 322 adults (18-89 years-old) regularly living in Brazil between March and October 2020 answered an online survey including questions considering the before and during SDIST period on PA (min/week) and morningness-eveningness questionnaire score. Sociodemographic, SDIST, anthropometric, and health characteristics were also included in the online survey. Participants self-reported an increase of eveningness preference comparing Before-SDIST with During-SDIST scores (56 ± 12 vs. 52 ± 13, p < .0001). Self-reported PA decreased comparing Before-SDIST with During-SDIST (230 ± 170 vs. 149 ± 155 min/week, p < .0001). Decrease in the total volume of PA and hours spent outside per day, and higher body mass index were associated with the increase in eveningness preference (R² = .077), although the decrease in the total volume of PA was the strongest association (R² = .037). In summary, our results show that SDIST may cause a delay in the circadian system, which is associated with the decrease of PA, a reduction in the hours spent outside per day with sunlight exposure, and obesity.

Exposure of Fischer 344 rats to distinct photoperiods influences the bioavailability of red grape polyphenols

The consumption of grapes, rich in polyphenols, have several health effects. These effects are mainly attributed to the polyphenol metabolites generated after their ingestion. Several factors that affects host's physiology can modulate the bioavailability of grape polyphenols and, in turn, their effects. Mammals undergo physiological and metabolic changes due to the different day length (photoperiod) within a year. Thus, the aim of this study is to investigate if the bioavailability of phenolic compounds from the same red grapes with a different polyphenol profile (i.e. red grape produced organically (OG) or non-organically (conventional, CG)) differs with the photoperiod exposure. For this, the serum phenolic metabolites of Fischer 344 rats keep at different photoperiods (18, 12 or 6 h of light per day) and administered with OG or CG for 10-week were profiled by HPLC-MS/MS. Our results indicated that rats administered with OG reported a higher total serum metabolite concentration independent of the photoperiod exposure and CG-administered rats showed a more varied serum metabolite profile depending of the photoperiod exposure. Those rats exposed to 6 h of light per day, which emulates winter light conditions, presented a higher bioavailability of grape phenolics. Therefore, grape cultivar and animal photoperiod exposure condition grape phenolics' bioavailability.

Daily, weekly and annual patterns in children's accidental sport injuries

Details of serious injuries to children ≤16 yrs. of age that necessitated urgent surgical intervention by the Department of Pediatric Surgery of the University Hospital of Lausanne, Switzerland were recorded into a database registry. Some 15 110 entries listed the precise time of injury, and 3114 (20.6%) of these resulted from participating in sport-associated activities. Time-of-day, day-of-week and month-of-year differences in the total number of children's accidental sport injuries (CASI) were validated. Time-of-day patterns were substantiated for "All Sports", for both boys and girls 5-16 yrs. of age, with more boys than girls experiencing incidents at almost every clock hour. Moreover, they were substantiated for this age group for each of the six different considered individual and team CASI categories - Physical Exercises at School; Bicycle Riding; Roller Skating and Skateboarding; Snow Skiing, Sledding, and Tobogganing; Soccer; and Basketball - for which sample sizes were sufficiently large (n > 230) to perform statistical assessment by ANOVA, t-test and/or cosinor analyses. CASI happened primarily between 06:00 and 17:00 h and rarely evening or overnight. Features - specific clock-time and number of peaks and troughs - of the CASI daily curve pattern of the individual six sport categories differed somewhat; nonetheless, excess or greatest number of CASI typically happened between 12:00 and 14:00 h, even when summertime and other scheduled school and family vacation periods were taken into account. Time-of-day and day-of-week patterns in the boy/girl sex ratio were also validated, with midday and Friday/Saturday peaks, respectively. We hypothesize the prominent 24 h patterns of CASI of 5-16 yr. olds, in particular, are representative of a combination of several determinants. These include exogenous periodic and cyclic environmental and sociocultural phenomena, genetic sex-related traits, plus endogenous circadian cognitive and physiologic rhythms, with the common midday injury excess of many sport categories, at least in part, the consequence of the well-documented midday dip in attention and vigilance of children.

Seasonal differences in rhythmicity of salivary cortisol in healthy adults

The existence of seasonal changes in secretion of stress hormones and inflammatory mediators by humans is not certain. Here, we aimed to determine whether concentrations of cortisol and IL-6 displayed seasonal rhythmicity. The study was performed in Poznań, Poland (52°N, 16°E) in 7 healthy female volunteers (age 22.6 ± 0.8 yr). Samples of whole mixed unstimulated saliva were collected in winter (February) and summer (June) at 2-h intervals over a 24-h period and analyzed for cortisol and IL-6 by immunoassays. During each season, the subjects answered questionnaires related to their sleeping habits, food intake, physical activity, and perceived seasonality. It turned out that salivary concentrations of cortisol followed a daily rhythm both in winter and summer, as determined by a cosine analysis. However, compared with the winter season, a midline-estimating statistic of rhythm in the summer was significantly higher. Moreover, the rhythm acrophase occurred ~4 h later in the summer than in the winter, whereas the amplitudes did not differ. These fluctuations did not correspond to sleeping habits, food and fluid intake, physical exercise, and the self-assessed chronotype. However, the individuals with higher scores on the seasonal affective disorder scale showed a tendency toward lower relative cortisol amplitude in the summer. In contrast to cortisol, salivary IL-6 concentration did not display daily rhythmicity, and its concentrations did not differ significantly between the seasons. In conclusion, in the summer, cortisol level in saliva is elevated, and its circadian pattern of secretion is shifted. The causes for these alterations do not seem to be related to lifestyle and thus remain to be established.

Intake of an Obesogenic Cafeteria Diet Affects Body Weight, Feeding Behavior, and Glucose and Lipid Metabolism in a Photoperiod-Dependent Manner in F344 Rats

We previously demonstrated that chronic exposure to different photoperiods induced marked variations in several glucose and lipid metabolism-related parameters in normoweight Fischer 344 (F344) rats. Here, we examined the effects of the combination of an obesogenic cafeteria diet (CAF) and the chronic exposure to three different day lengths (L12, 12 h light/day; L18, 18 h light/day; and L6, 6 h light/day) in this rat strain. Although no changes were observed during the first 4 weeks of adaptation to the different photoperiods in which animals were fed a standard diet, the addition of the CAF for the subsequent 7 weeks triggered profound physiologic and metabolic alterations in a photoperiod-dependent manner. Compared with L12 rats, both L6 and L18 animals displayed lower body weight gain and cumulative food intake in addition to decreased energy expenditure and locomotor activity. These changes were accompanied by differences in food preferences and by a sharp upregulation of the orexigenic genes Npy and Ghsr in the hypothalamus, which could be understood as a homeostatic mechanism for increasing food consumption to restore body weight control. L18 rats also exhibited higher glycemia than the L6 group, which could be partly attributed to the decreased pAkt2 levels in the soleus muscle and the downregulation of Irs1 mRNA levels in the gastrocnemius muscle. Furthermore, L6 animals displayed lower whole-body lipid utilization than the L18 group, which could be related to the lower lipid intake and to the decreased mRNA levels of the fatty acid transporter gene Fatp1 observed in the soleus muscle. The profound differences observed between L6 and L18 rats could be related with hepatic and muscular changes in the expression of circadian rhythm-related genes Cry1, Bmal1, Per2, and Nr1d1. Although further research is needed to elucidate the pathophysiologic relevance of these findings, our study could contribute to emphasize the impact of the consumption of highly palatable and energy dense foods regularly consumed by humans on the physiological and metabolic adaptations that occur in response to seasonal variations of day length, especially in diseases associated with changes in food intake and preference such as obesity and seasonal affective disorder.

Consumption of Cherry out of Season Changes White Adipose Tissue Gene Expression and Morphology to a Phenotype Prone to Fat Accumulation

The aim of this study was to determine whether the consumption of cherry out of its normal harvest photoperiod affects adipose tissue, increasing the risk of obesity. Fischer 344 rats were held over a long day (LD) or a short day (SD), fed a standard diet (STD), and treated with a cherry lyophilizate (CH) or vehicle (VH) (n = 6). Biometric measurements, serum parameters, gene expression in white (RWAT) and brown (BAT) adipose tissues, and RWAT histology were analysed. A second experiment with similar conditions was performed (n = 10) but with a cafeteria diet (CAF). In the STD experiment, Bmal1 and Cry1 were downregulated in the CHSD group compared to the VHSD group. Pparα expression was downregulated while Ucp1 levels were higher in the BAT of the CHSD group compared to the VHSD group. In the CAF-fed rats, glucose and insulin serum levels increased, and the expression levels of lipogenesis and lipolysis genes in RWAT were downregulated, while the adipocyte area increased and the number of adipocytes diminished in the CHSD group compared to the VHSD group. In conclusion, we show that the consumption of cherry out of season influences the metabolism of adipose tissue and promotes fat accumulation when accompanied by an obesogenic diet.

The Exposure to Different Photoperiods Strongly Modulates the Glucose and Lipid Metabolisms of Normoweight Fischer 344 Rats

Seasonal variations in day length trigger clear changes in the behavior, growth, food intake, and reproductive status of photoperiod-sensitive animals, such as Fischer 344 rats. However, there is little information about the effects of seasonal fluctuations in day length on glucose and lipid metabolisms and their underlying mechanisms in this model. To gain knowledge on these issues, three groups of male Fischer 344 rats were fed with a standard diet and exposed to different photoperiods for 14 weeks: normal photoperiod (L12, 12 h light/day), long photoperiod (L18, 18 h light/day), and short photoperiod (L6, 6 h light/day). A multivariate analysis carried out with 239 biometric, serum, hepatic and skeletal muscle parameters revealed a clear separation among the three groups. Compared with L12 rats, L6 animals displayed a marked alteration of glucose homeostasis and fatty acid uptake and oxidation, which were evidenced by the following observations: (1) increased circulating levels of glucose and non-esterified fatty acids; (2) a sharp down-regulation of the phosphorylated Akt2 levels, a downstream post-receptor target of insulin, in both the soleus and gastrocnemius muscles; (3) decreased expression in the soleus muscle of the glucose metabolism-related microRNA-194 and lower mRNA levels of the genes involved in glucose metabolism (Irs1, soleus, and Glut2, liver), β-oxidation (Had and Cpt1β, soleus) and fatty acid transport (Cd36, soleus, and liver). L18 animals also displayed higher blood glucose levels than L12 rats and profound changes in other glucose and lipid metabolism-related parameters in the blood, liver, and skeletal muscles. However, the mechanisms that account for the observed effects were less evident than those reported in L6 animals. In conclusion, exposure to different photoperiods strongly modulated glucose and lipid metabolisms in normoweight rats. These findings emphasize the relevance of circannual rhythms in metabolic homeostasis regulation and suggest that Fischer 344 rats are a promising animal model with which to study glucose- and lipid-related pathologies that are influenced by seasonal variations, such as obesity, cardiovascular disease and seasonal affective disorder.

Participation as a leader in immersion weight loss treatment: a 1-year follow-up study

Non-overweight individuals may follow aggressive weight management approaches alongside overweight/obese friends or family members; thus, research has begun to evaluate subsequent effects among non-overweight populations. A prior study evaluated the short-term effects of an immersion weight loss programme on healthy young adult staff leaders. Results indicated that participation seemed to benefit, not harm, the young adults. The current investigation examined 1-year eating disorder and weight trajectories in this sample. The total sample (N = 244) consisted of staff leaders (44.3%) and demographically similar comparison participants who completed eating disorder and weight assessments across four time points: baseline, end of summer, 6-week follow-up and 1-year follow-up. Forty-seven per cent of the original sample responded to all time points (staff leaders n = 60; comparison n = 55). Over the course of 1 year, risk trajectories did not differ between groups. Staff leaders did not report significant changes in body mass index, suggesting that they maintained healthy weight over the course of 1 year. Participation as an immersion weight loss programme leader appeared to be protective against weight gain, without increasing eating disorder risk, for healthy young adults. This provides further support for using weight management interventions across a wide range of individuals.

Too hot to move? Objectively assessed seasonal changes in Australian children's physical activity

Background

Seasonal variations may influence children’s physical activity patterns. The aim of this study was to examine how children’s objectively-measured physical activity differed across seasons, and whether different seasonal patterns were observed for boys and girls.

Methods

Three hundred and twenty-six children aged 8–11 years from nine primary schools in Melbourne, Australia, participated in the study. Physical activity was measured every 15-s using hip-mounted GT3X+ ActiGraph accelerometers for seven consecutive days in the Winter (n = 249), Spring (n = 221), Summer (n = 174) and Autumn (n = 152) school terms. Time spent in moderate (MPA), vigorous (VPA) and moderate- to vigorous-intensity physical activity (MVPA) at each time point was derived using age-specific cut-points. Meteorological data (maximum temperature, precipitation, daylight hours) were obtained daily during each season. Longitudinal data were analysed using multilevel analyses, adjusted for age, sex, accelerometer wear time, number of valid days, and meteorological variables.

Results

Compared to Winter, children engaged in significantly less MPA (−5.0 min) and MVPA (−7.8 min) in Summer. Girls engaged in less MVPA in Spring (−18 min) and Summer (−9.2 min) and more MVPA in Autumn (9.9 min) compared to Winter. Significant changes in MPA and VPA bout frequency and duration were also observed. Significant decreases in VPA bout frequency (3.4 bouts) and duration (2.6 min) were observed for girls in Spring compared to Winter. No significant seasonal changes were observed for boys for all intensities and physical activity accumulation.

Conclusions

Physical activity decreased in Summer compared to Winter, contrasting previous research that typically reports that children are most active in summer. Greater fluctuations were observed for girls’ activity levels. In addition, girls’ activity duration and bouts appeared to be more susceptible to seasonal changes compared to boys. The results suggest that strategies to promote physical activity may be needed in Australia during the hot summer months, particularly for girls.

Contribution of daily and seasonal biorhythms to obesity in humans

While the significance of obesity as a serious health problem is well recognized, little is known about whether and how biometerological factors and biorhythms causally contribute to obesity. Obesity is often associated with altered seasonal and daily rhythmicity in food intake, metabolism and adipose tissue function. Environmental stimuli affect both seasonal and daily rhythms, and the latter are under additional control of internal molecular oscillators, or body clocks. Modifications of clock genes in animals and changes to normal daily rhythms in humans (as in shift work and sleep deprivation) result in metabolic dysregulation that favours weight gain. Here, we briefly review the potential links between biorhythms and obesity in humans.

Physical activity during work, transport and leisure in Germany--prevalence and socio-demographic correlates

BACKGROUND

This study aimed 1) to provide data estimates concerning overall moderate- and vigorous-intensity physical activity (MVPA) as well as MVPA during work, transport and leisure in Germany and 2) to investigate MVPA and possible associations with socio-demographic correlates.

METHODS

A cross-sectional telephone survey interviewed 2248 representative participants in the age of 18-65 years (1077 men; 42.4 ± 13.4 years; body mass index: 25.3 ± 4.5 kg • m(-2)) regarding their self-reported physical activity across Germany. The Global Physical Activity Questionnaire was applied to investigate MVPA during work, transport and leisure and questions were answered concerning their demographics. MVPA was stratified by gender, age, body mass index, residential setting, educational and income level. To identify socio-demographic correlates of overall MVPA as well as in the domains, we used a series of linear regressions.

RESULTS

52.8% of the sample achieved physical activity recommendations (53.7% men/52.1% women). Overall MVPA was highest in the age group 18-29 years (p < .05), in participants with 10 years of education (p < .05) and in participants with lowest income levels < 1.500 € (p < .05). Regression analyses revealed that age, education and income were negatively associated with overall and work MVPA. Residential setting and education was positively correlated with transport MVPA, whereas income level was negatively associated with transport MVPA. Education was the only correlate for leisure MVPA with a positive association.

CONCLUSIONS

The present data underlines the importance of a comprehensive view on physical activity engagement according to the different physical activity domains and discloses a need for future physical activity interventions that consider socio-demographic variables, residential setting as well as the physical activity domain in Germany.

Variability and seasonality of active transportation in USA: evidence from the 2001 NHTS

BACKGROUND

Active transportation including walking and bicycling is an important source of physical activity. Promoting active transportation is a challenge for the fields of public health and transportation. Descriptive data on the predictors of active transportation, including seasonal patterns in active transportation in the US as a whole, is needed to inform interventions and policies.

METHODS

This study analyzed monthly variation in active transportation for the US using National Household Travel Survey 2001 data. For each age group of children, adolescents, adults and elderly, logistic regression models were used to identify predictors of the odds of active transportation including gender, race/ethnicity, household income level, geographical region, urbanization level, and month.

RESULTS

The probability of engaging in active transportation was generally higher for children and adolescents than for adults and the elderly. Active transportation was greater in the lower income groups (except in the elderly), was lower in the South than in other regions of the US, and was greater in areas with higher urbanization. The percentage of people using active transportation exhibited clear seasonal patterns: high during summer months and low during winter months. Children and adolescents were more sensitive to seasonality than other age groups. Women, non-Caucasians, persons with lower household income, who resided in the Midwest or Northeast, and who lived in more urbanized areas had greater seasonal variation.

CONCLUSIONS

These descriptive results suggest that interventions and policies that target the promotion of active transportation need to consider socio-demographic factors and seasonality.

Seasonal variations in physical activity and implications for human health

This review explores the implications of seasonal changes in physical activity for fitness and human health. Photosensitivity and nutrient shortages mediate animal hibernation via the hypothalamus and changes in leptin and ghrelin concentrations. Opportunities for hunting and crop cultivation determine seasonal activity in under-developed human societies, but in developed societies temperature and rainfall are dominant influences, usually over-riding innate rhythms. Both questionnaire data and objective measurements show that many groups from children to the elderly increase their physical activity from winter to spring or summer. Measurements of maximal oxygen intake and muscle strength commonly show parallel seasonal changes. However, potential effects upon body mass and body fat may be counteracted by changes of food intake; subsistence agriculturists sometimes maintain or increase physical activity at the expense of a decrease in body mass. In developed societies, body fat commonly increases during the winter, with parallel changes in blood lipids, blood pressure and blood coagulability; moreover, these changes are not always fully reversed the following summer. Most developed societies show increased all-cause and cardiac mortalities in the winter. Health consequences of seasonal variations in physical activity including an increased vulnerability to cardiac catastrophe and a year-by-year increase in total body fat seem most likely if the average level of physical activity for the year is low. Public health recommendations should underline the importance of maintaining physical activity during adverse environmental conditions by adapting clothing, modifying behaviour and exploiting any available air-conditioned indoor facilities.

Supporting diabetes self-management in primary care: pilot-study of a group-based programme focusing on diet and exercise

AIMS

To develop and implement a group self-management education programme for people with type 2 diabetes at the community level in primary care. This pilot-study intended to evaluate the feasibility, acceptability and long-term effects (12-18 months) of this programme on emotional distress, HbA1c, BMI and actual behaviour.

METHODS

An empowerment-based, theory-driven education programme was evaluated in a before-after design. The programme focused on behaviour assessment, goal-setting, problem solving and tailored information. A diabetes specialist nurse conjointly with a dietician or psychologist led five 2-hour sessions and a follow-up meeting after 3 months.

RESULTS

Forty-four people participated in 5 groups. BMI decreased with 0.45 kg/m(2) (95%CI 0.01-0.89) at 12-month and with 0.53 kg/m(2) (95%CI 0.02-1.04) at 18-month follow-up. HbA1c declined from 7.4% (+/-1.3) to 6.8% (+/-0.8) (p=0.040) and the PAID-score diminished from 28 (+/-20) to 18 (+/-13) (p=0.006) at 12-month post-intervention. These changes were only partly sustained at 18-month follow-up. Actual behaviour changed modestly.

CONCLUSION

Introducing the group education programme in primary healthcare is worthwhile (feasibility and effectiveness). A detailed description of the intervention is offered. Further research should explore the actual education process in greater depth.