Sindre M. Dyrstad

Comparison of self-reported versus accelerometer-measured physical activity.

INTRODUCTION The International Physical Activity Questionnaire (IPAQ) is one of the most widely used questionnaires to assess physical activity (PA). Validation studies for the IPAQ have been executed, but still there is a need for studies comparing absolute values between IPAQ and accelerometer in large population studies. PURPOSE To compare PA and sedentary time from the self-administered, short version of the IPAQ with data from ActiGraph accelerometer in a large national sample. METHODS A total of 1751 adults (19-84 yr) wore an accelerometer (ActiGraph GT1M) for seven consecutive days and completed the IPAQ-Short Form. Sedentary time, total PA, and time spent in moderate to vigorous activity were compared in relation to sex, age, and education. RESULTS Men and women reported, on average, 131 min·d (SE = 4 min·d) less sedentary time compared with the accelerometer measurements. The difference between self-reported and measured sedentary time and vigorous-intensity PA was greatest among men with a lower education level and for men 65 yr and older. Although men reported 47% more moderate to vigorous physical activity (MVPA) compared with women, there were no differences between sexes in accelerometer-determined MVPA. Accelerometer-determined moderate PA was reduced from 110 to 42 min·d (62%) when analyzed in blocks of 10 min (P < 0.0001) compared with 1-min blocks. The main correlation coefficients between self-reported variables and accelerometer measures of physical activity were between 0.20 and 0.46. CONCLUSIONS The participants report through IPAQ-Short Form more vigorous PA and less sedentary time compared with the accelerometer. The difference between self-reported and accelerometer-measured MVPA increased with higher activity and intensity levels. Associations between the methods were affected by sex, age, and education, but not body mass index.

Accelerometer-Determined Physical Activity in Adults and Older People

PURPOSE There is a lack of large-scale comparable data on the population levels of physical activity (PA) and sedentary activity. We conducted a cross-sectional population-based multicenter study to describe the levels of PA and sedentary activity and to determine adherence to current national PA recommendations in Norwegian adults and older people. METHODS In 2008 and 2009, PA was assessed objectively for seven consecutive days using the ActiGraph GT1M accelerometer in 3867 participants age 20-85 yr. A total of 3267 participants provided valid PA assessments that met all inclusion criteria. RESULTS Women and men did not differ in the overall activity levels (335 and 342 counts per minute, respectively) or in steps per day (8113 and 7951 steps per day, respectively). However, for intensity-specific PA, men accumulated significantly more minutes of sedentary activity and moderate-to-vigorous PA (MVPA) compared with women (557 vs 533 min of sedentary activity, P ≤ 0.001 and 35 vs 33 min of MVPA, P = 0.01). Both overall activity levels and steps per day remained steady with age, until 65 yr, after which activity levels declined. CONCLUSIONS Overall, the study sample spent 62% of their time being sedentary, 25% in low-intensity PA, 9% in lifestyle activity, and 4% in MVPA. One in five people met current national PA recommendations. These results suggest that adults and older people spend the majority of their time being sedentary and that adherence to PA recommendations is low.

Stress in obesity: Cause or consequence?

Obesity is a global public health challenge that increases the risk of various diseases including type 2 diabetes mellitus, hypertension and cancer, and will in the future cause further increases in the incidence of chronic disease. Understanding the mechanisms of obesity is critical if we are to prevent and treat this pandemic challenge. Diet and physical activity have traditionally been the major tasks in preventing and treating obesity. However, other mechanisms are now also being considered in the quest for knowledge and understanding of obesity, including the bodys stress system and cortisol release. While it seems evident that stress is a cause of obesity, whether stress is also a consequence of obesity has up to now only briefly been discussed. The aim of this article is to elucidate how stress and obesity might be linked and discuss the cause/consequence relationship between the stress response and obesity. Our hypothesis is that stress and obesity interfere by positive feedback. This may be an important issue in both our understanding and coping of obesity.

Aerobic fitness in young Norwegian men: a comparison between 1980 and 2002

The purpose of this study was to compare the maximal oxygen uptake (VO2max) in 18–19‐year‐old Norwegian men from 1980 to 1985 and 2002. In addition, we investigated the relationship between VO2max and education and smoking habits in the sample from 2002. From 1980 to 1985, VO2max was predicted using the Åstrand–Rhyming bicycle test for 183 610 eighteen‐year‐old Norwegian men (91% of the male Norwegian population in this age group). In 2002, the same test was performed on a representative sample of the same age population (N=1028). VO2max (mL × kg−1× min−1), decreased by 8%, body weight increased by 7% and body mass index (BMI) increased by 6% over the approximately 20‐year period (P<0.01). Results from the 2002 sample revealed that smokers had a lower VO2max than non‐smokers and vocational students had a lower VO2max than academic students (P<0.05). The average reduction in VO2max was because of an increased number of men with low or very low VO2max, and a reduced number of men with high VO2max values. This is of particular concern since the prevalence of lifestyle‐related diseases is higher in groups with low VO2max.

Effects of scheduled exercise on cancer-related fatigue in women with early breast cancer

While physical activity during cancer treatment is found beneficial for breast cancer patients, evidence indicates ambiguous findings concerning effects of scheduled exercise programs on treatment-related symptoms. This study investigated effects of a scheduled home-based exercise intervention in breast cancer patients during adjuvant chemotherapy, on cancer-related fatigue, physical fitness, and activity level. Sixty-seven women were randomized to an exercise intervention group (n = 33, performed strength training 3x/week and 30 minutes brisk walking/day) and a control group (n = 34, performed their regular physical activity level). Data collection was performed at baseline, at completion of chemotherapy (Post1), and 6-month postchemotherapy (Post2). Exercise levels were slightly higher in the scheduled exercise group than in the control group. In both groups, cancer-related fatigue increased at Post1 but returned to baseline at Post2. Physical fitness and activity levels decreased at Post1 but were significantly improved at Post2. Significant differences between intervention and control groups were not found. The findings suggest that generally recommended physical activity levels are enough to relief cancer-related fatigue and restore physical capacity in breast cancer patients during adjuvant chemotherapy, although one cannot rule out that results reflect diminishing treatment side effects over time.

Secular trends in aerobic fitness performance in a cohort of Norwegian adolescents

The purpose of the present study was to compare 3000 m running test results between 1969 and 2009 in a cohort of Norwegian high school pupils. Between 1969 and 2009, a total of 4981 (2827 boys) 3000 m running tests were collected from two Norwegian senior high schools. One‐way ANOVA with Tukeys post hoc test was used to analyze the differences in the running times between the different decades. The running times have increased by 10% and 6% from the 1980s to the 2000s for boys and girls, respectively. The distribution showed a decline in aerobic fitness performance for all deciles. The largest negative change in difference was found for pupils with the poorest aerobic fitness level in both boys and girls. The cohort of 16‐ to 18‐year‐old boys and girls in the decade 2000–2009 had a poorer aerobic fitness performance in the 3000 m running test compared with earlier decades. The decline in running performance was greater for boys than girls, and the gap between the most and the least fit is becoming considerably larger.

Physical fitness, training volume, and self-determined motivation in soldiers during a peacekeeping mission.

PURPOSE The goal was to register physical training volume and to measure changes in physical fitness in soldiers during a peacekeeping mission. The relationship between these factors and motivation for physical training was also investigated. METHODS Physical training volume was registered and maximal oxygen uptake, 3-km run time, sit-ups, push-ups, and chin-ups were tested before and after 1 year of service for 71 Norwegian soldiers in the international Kosovo Force. Self-determined motivation was measured at the end of the service. RESULTS Physical training volume was 117 +/- 77 minutes/week. The average maximal oxygen uptake decreased by 2.5 +/- 0.8% (p < 0.01). Intrinsic motivation positively predicted physical training volume (p < 0.01). CONCLUSIONS A large variation in training volume was found, and only one-third of the soldiers improved physical fitness and maintained body weight. Fostering intrinsic motivation toward physical training is key to increasing training volume. However, obligatory training could ensure a minimum of physical training among the soldiers who were least motivated for physical training.

Cardiorespiratory fitness in groups with different physical activity levels

The aim of the study was to determine how different categorizations of self‐reported and objectively measured physical activity (PA) reflect variations in cardiorespiratory fitness (VO2max). A total of 759 individuals (366 women) with a mean age of 48.5 years (SD 14.4) wore an accelerometer (ActiGraph GT1M) for seven consecutive days and answered the short International Physical Activity Questionnaire (IPAQ). VO2max was directly measured during a continuous graded exercise treadmill test until exhaustion. Men and women categorized as highly active by IPAQ had 9% and 13% higher VO2max, respectively, than those reporting a low PA level (P < 0.05). Men and women meeting the PA recommendation of 150 min/week of daily moderate intensity PA, measured by accelerometer, had 13% and 9% higher VO2max, respectively, than participants not meeting this recommendation (P < 0.01). No significant differences in average sedentary time, analyzed in total min/day and in bouts of 10 and 30 min, were found between participants with high or low cardiorespiratory fitness. However, women spent less time than men in bouts of sedentary behaviors. Self‐reported PA by IPAQ and objectively measured PA by accelerometer were both useful instruments for detecting differences in VO2max.

Health effects of cycling to and from work

BACKGROUND The purpose of the study was to assess whether people could be motivated in a simple way to cycle regularly to and from work during one year, and to assess whether this could lead to any health-related physiological benefits. MATERIAL AND METHODS 25 persons who cycled to and from work during one year were included in the study. Maximum oxygen uptake (VO2max) and body mass index (BMI) were measured at baseline, after six months and after one year. Total-cholesterol (TC) and HDL-cholesterol (HDL) were measured at the start and the end of the project. RESULTS During the study VO 2max increased with 15.8 %; from 32.5 (8.1: SD) to 37.1 (7.6) ml x kg(-1) x min(-1) (p < 0.001). HDL-cholesterol increased with 15.3 %; from 1.31 (0.31) to 1.51 (0.40) mmol x l(-1) (p < 0.001). No changes were recorded for BMI. The numbers of cycling sessions were greatly reduced during the winter months because of poor cycling conditions. INTERPRETATION This study shows that cycling to and from work may positively affect physiological variables and thereby have a beneficial health effect.

Does increased physical activity in school affect children's executive function and aerobic fitness?

This study seeks to explore whether increased PA in school affects childrens executive function and aerobic fitness. The “Active school” study was a 10‐month randomized controlled trial. The sample included 449 children (10‐11 years old) in five intervention and four control schools. The weekly interventions were 2×45 minutes physically active academic lessons, 5×10 minutes physically active breaks, and 5×10 minutes physically active homework. Aerobic fitness was measured using a 10‐minute interval running test. Executive function was tested using four cognitive tests (Stroop, verbal fluency, digit span, and Trail Making). A composite score for executive function was computed and used in analyses. Mixed ANCOVA repeated measures were performed to analyze changes in scores for aerobic fitness and executive function. Analysis showed a tendency for a time×group interaction on executive function, but the results were non‐significant F(1, 344)=3.64, P=.057. There was no significant time×group interaction for aerobic fitness. Results indicate that increased physical activity in school might improve childrens executive function, even without improvement in aerobic fitness, but a longer intervention period may be required to find significant effects.