Physical activity patterns using accelerometry in the National Weight Control Registry

The National Weight Control Registry (NWCR) was established in 1993 to examine characteristics of successful weight‐loss maintainers. This group consistently self‐reports high levels of physical activity. The aims of this study were to obtain objective assessments of physical activity in NWCR subjects and compare this to physical activity in both normal‐weight and overweight controls. Individuals from the NWCR (n = 26) were compared to a never obese normal‐weight control group matched to the NWCR group's current BMI (n = 30), and an overweight control group matched to the NWCR group's self‐reported pre‐weight‐loss BMI (n = 34). Objective assessment of physical activity was obtained for a 1‐week period using a triaxial accelerometer. Bouts of moderate‐to‐vigorous physical activity (MVPA) ≥10 min in duration, as well as nonbout MVPA (bouts of MVPA 1–9 min in duration) were summed and characterized. NWCR subjects spent significantly (P = 0.004) more time per day in sustained bouts of MVPA than overweight controls (41.5 ± 35.1 min/day vs. 19.2 ± 18.6 min/day) and marginally (P = 0.080) more than normal controls (25.8 ± 23.4). There were no significant differences between the three groups in the amount of nonbout MVPA. These results provide further evidence that physical activity is important for long‐term maintenance of weight loss and suggest that sustained volitional activity (i.e., ≥10 min in duration) may play an important role. Interventions targeting increases in structured exercise may be needed to improve long‐term weight‐loss maintenance.     

A Pilot of a Video Game (DDR) to Promote Physical Activity and Decrease Sedentary Screen Time

Objective: We examined the feasibility of Dance Dance Revolution (DDR), a dance video game, in participants' homes, to increase physical activity (PA) and to decrease sedentary screen time (SST). Methods And Procedures: Sixty children (7.5 ± 0.5 years) were randomized in a 2:1 ratio to DDR or to wait‐list control (10‐week delay). DDR use was logged, PA was measured objectively by accelerometry. SST was self‐reported at weeks 0 and 10. At week 28, after both groups had access to DDR, accelerometry and SST were repeated. Results: Mean use of DDR was 89 ± 82 (range 0–660min) min per week (mpw). The DDR group showed increased vigorous PA and a reduction in light PA; the control group showed no increase in moderate and/or vigorous PA (MVPA) although they also had a reduction in light PA. Differences between the groups were not observed. The DDR group also reported a decrease in SST of ?1.2 ± 3.7 h per week (hpw) (P < 0.05), whereas the controls reported an increase of +3.0 ± 7.7 hpw (nonsignificant). The difference in SST between the groups was significant, with less SST in the DDR group. Between weeks 10 and 28, numeric reductions in SST were reported in both groups. In the DDR group, SST at week 28 (8.8 ± 6.0 hpw) was lower than baseline (10.5 ± 5.5 hpw; P < 0.03). Discussion: This pilot study suggests that DDR reduces SST and may facilitate slight increases in vigorous PA. Further study is needed to better characterize children and contexts in which DDR may promote a healthy lifestyle.     

The Effect of Physical Activity on 18‐Month Weight Change in Overweight Adults

Few studies have been conducted that have examined the long‐term effect of different doses of physical activity (PA) on weight change in overweight adults without a prescribed reduction in energy intake. This study examined the effect of different prescribed doses of PA on weight change, body composition, fitness, and PA in overweight adults. Two hundred seventy‐eight overweight adults (BMI: 25.0–29.9 kg/m²; age: 18–55 years) with no contraindications to PA were randomized to one of three intervention groups for a period of 18 months. MOD‐PA was prescribed 150 min/week and HIGH‐PA 300 min/week of PA. Self‐help group (SELF) was provided a self‐help intervention to increase PA. There was no recommendation to reduce energy intake. MOD‐PA and HIGH‐PA were delivered in a combination of in‐person and telephone contacts across 18 months. 18‐month percent weight change was ?0.7 ± 4.6% in SELF, ?0.9 ± 4.7% in MOD‐PA, and ?1.2 ± 5.6% in HIGH‐PA. Subjects were retrospectively grouped as remaining within ±3% of baseline weight (WT‐STABLE), losing >3% of baseline weight (WT‐LOSS), or gaining >3% of baseline weight (WT‐GAIN) for secondary analyses. 18‐month weight change was 0.0 ± 1.3% for WT‐STABLE, +5.4 ± 2.6% for WT‐GAIN, and ?7.4 ± 3.6% for WT‐LOSS. 18‐month change in PA was 78.2 ± 162.6 min/week for WT‐STABLE, 74.7 ± 274.3 for WT‐GAIN, and 161.9 ± 252.6 min/week for WT‐LOSS. The weight change observed in WT‐LOSS was a result of higher PA combined with improved scores on the Eating Behavior Inventory (EBI), reflecting the adoption of eating behaviors to facilitate weight loss. Strategies to facilitate the maintenance of these behaviors are needed to optimize weight control.     

Levels and Patterns of Objectively Assessed Physical Activity and Compliance with Different Public Health Guidelines in University Students

Background

Physical activity (PA) is associated with health enhancement. The aim of this study was to assess: 1) levels and patterns of PA in university students by using accelerometers; and 2) the percentage of fulfilment of PA recommendations for adults, according to different public health guidelines.

Methods

Observational cross-sectional study (Cuenca’s Adults Study) involving 296 (206 women) healthy Spanish university students aged 18–25 years old. Participants wore the ActiGraph GT1M accelerometer for seven consecutive days. Total PA, steps and time spent in sedentary time, light, moderate, vigorous, and moderate to vigorous PA (MVPA) was assessed, and the prevalence of sufficient PA was calculated according to various public health guidelines.

Results

No sex differences in total PA were found. University students were more sedentary during weekend days than weekdays (p<0.05). Only 30.3% of participants accumulated 30 min/day at least five days a week of MVPA. A total of 5.4% of students met the recommendation of 150 min/week of MVPA or 75 min/week of vigorous PA, in PA bouts of at least 10 min. using the same definition, but on five or more days a week, only 0.5% students were found to meet the recommendation. In addition, only 0.5% of students met the recommendation of 30 min/day of MVPA, at least five days a week and in bouts of at least 10 min. Finally, 28.1% of the students met the recommendation of 10,000 steps/day.

Conclusions

Our study shows a high incidence of sedentary time in university students. The number of students meeting PA recommendations significantly differed depending on the recommendation proposed. Specific strategies to promote PA in this population are necessary as well as an agreement as to which PA guidelines should be used.     

Independent Evolution of Heart Autonomic Function and Insulin Sensitivity During Weight Loss

In order to investigate the improvement of insulin resistance and cardiac autonomic function along massive weight loss, 12 obese women were evaluated before, and 3 and 12 months after Roux‐en‐Y gastric bypass. The 12‐month values were compared to those of BMI‐matched controls. Insulin sensitivity was assessed by euglycemic clamp and the cardiac autonomic function by the analysis of the Heart Rate Variability (HRV). After surgery, glucose uptake progressively increased from 4.3 ± 0.5 mg/kg lean body mass (LBM)/min preoperative (pre‐op) to 4.9 ± 0.5 and 7.0 ± 0.5, 3‐ and 12‐month postoperative (post‐op) (P = 0.04 and P = 0.006 vs. pre‐op), whereas the cardiac autonomic function showed a biphasic pattern. HRV values increased 3 months post‐op, and decreased at 12 months, thus indicating an early sympathetic withdrawal followed by a later reactivation (e.g., the standard deviation of the normal‐to‐normal intervals was 116 ± 7 ms in pre‐op, 161 ± 10 at 3 months, P = 0.008 vs. pre‐op, and 146 ± 15 at 12 months, P = 0.03 vs. pre‐op and P = 0.02 vs. 3 m). Insulin sensitivity was significantly related to body weight (P = 0.02), whereas the cardiac indexes were significantly linked to the profile of energy intake (e.g., HRV triangular index vs. energy intake P = 0.003). No significant relationship linked insulin sensitivity to the cardiac autonomic indexes. Insulin sensitivity and cardiac parameters of the 12‐month post‐op patients were similar to their matched controls. During massive weight loss, the cardiac autonomic deregulation and insulin resistance improved concomitantly but independently from each other. Our results suggest that the extent of the improvement is associated with the final body weight.     

Resistance Training Preserves Fat‐free Mass Without Impacting Changes in Protein Metabolism After Weight Loss in Older Women

This study assessed the effects of resistance training (RT) on energy restriction–induced changes in body composition, protein metabolism, and the fractional synthesis rate of mixed muscle proteins (FSRm) in postmenopausal, overweight women. Sixteen women (age 68 ± 1 years, BMI 29 ± 1 kg/m², mean ± s.e.m.) completed a 16‐week controlled diet study. Each woman consumed 1.0 g protein/kg/day. At baseline (weeks B1–B3) and poststudy (weeks RT12–RT13), energy intake matched each subject's need and during weeks RT1–RT11 was hypoenergetic by 2,092 kJ/day (500 kcal/day). From weeks RT1 to RT13, eight women performed RT 3 day/week (RT group) and eight women remained sedentary (SED group). RT did not influence the energy restriction–induced decrease in body mass (SED ?5.8 ± 0.6 kg; RT ?5.0 ± 0.2 kg) and fat mass (SED ?4.1 ± 0.9 kg; RT ?4.7 ± 0.5 kg). Fat free mass (FFM) and total body water decreased in SED (?1.6 ± 0.4 and ?2.1 ± 0.5 kg) and were unchanged in RT (?0.3 ± 0.4 and ?0.4 ± 0.7 kg) (group‐by‐time, P ≤ 0.05 and P = 0.07, respectively). Protein–mineral mass did not change in either group (SED 0.4 ± 0.2 kg; RT 0.1 ± 0.4 kg). Nitrogen balance, positive at baseline (2.2 ± 0.3 g N/day), was unchanged poststudy. After body mass loss, postabsorptive (PA) and postprandial (PP) leucine turnover, synthesis, and breakdown decreased. Leucine oxidation and balance were not changed. PA and total (PA + PP) FSRm in the vastus lateralis were higher after weight loss. RT did not influence these protein metabolism responses. In summary, RT helps older women preserve FFM during body mass loss. The comparable whole‐body nitrogen retentions, leucine kinetics, and FSRm between groups are consistent with the lack of differential protein–mineral mass change.     

Relationship Between Self‐report and an Objective Measure of Television‐viewing Time in Adults

This study compared self‐reported television (TV)‐viewing time with an objective measure obtained by an electronic TV monitor. As part of a larger study, 40 overweight and obese adults (BMI: 31.7 ± 5.4 kg/m²; 53% obese; mean age 41.4 ± 13.0) self‐reported TV‐viewing time at study entry as the response to the question, “How many hours do you watch TV per day, on average?” Objective TV‐viewing time was measured in min/day over 3 weeks/subject using electronic monitors. Self‐reported viewing time was 4.3 ± 1.3 h/day (mean ± s.d.) (range: 3.0–8.0 h/day) vs. 4.9 ± 2.6 h/day (0.8–13.3 h/day) recorded by the electronic TV monitor. Subjects underestimated their viewing time by 0.6 ± 2.3 h/day (95% confidence interval = ?1.34, 0.13), or 4.3 h/week. Slightly over half of the subjects (58%) underestimated their viewing time; 47.5% were within 1 h/day, and 72.5% were within 2 h/day of self‐reported viewing time. Large errors were rare in this group, suggesting that a simple self‐report measure of TV time may be useful for characterizing viewing behavior, although objective measurement adds precision that may be useful in certain settings.     

Plasma visfatin concentrations in severely obese subjects are increased after intestinal bypass

Objective: Visfatin has shown to be increased in obesity and in type 2 diabetes. The aim of this study was to determine the change in plasma visfatin in severely obese (SO) persons after weight loss following bariatric surgery in relation to glucose concentration. Research Methods and Procedures: Visfatin and leptin were studied in 53 SO persons (BMI, 54.4 ± 6.8 kg/m²) before and 7 months after bariatric surgery and in 28 healthy persons (BMI, 26.8 ± 3.8 kg/m²). All of the patients underwent bariatric surgery with biliopancreatic diversion or gastric bypass. Results: The pre‐surgery levels of visfatin in the SO group were greater than in the control group (55.9 ± 39.9 vs. 42.9 ± 16.6 ng/mL, p = 0.024). This increase was significant in the SO group with impaired fasting glucose (63.4 ± 36.6 ng/mL) and diabetes (60.0 ± 46.0 ng/mL). SO patients with normal fasting glucose had similar levels of visfatin to the controls. Seven months after surgery, visfatin levels were significantly increased (84.8 ± 32.8 ng/mL, p < 0.001). This increase was independent of the pre‐surgical glucose levels. The type of bariatric surgery had no influence on visfatin levels. Post‐surgical visfatin was significantly correlated with the post‐surgery plasma concentrations of leptin (r = 0.39, p = 0.014). Discussion: Plasma levels of visfatin in the SO group were increased but only when accompanied by high glucose levels, even in the range of impaired fasting glucose. Bariatric surgery causes an increase in visfatin, which is correlated mainly with the changes produced in the leptin concentration.     

A Primary Care Nurse-Delivered Walking Intervention in Older Adults: PACE (Pedometer Accelerometer Consultation Evaluation)-Lift Cluster Randomised Controlled Trial

Background

Brisk walking in older people can increase step-counts and moderate to vigorous intensity physical activity (MVPA) in ≥10-minute bouts, as advised in World Health Organization guidelines. Previous interventions have reported step-count increases, but not change in objectively measured MVPA in older people. We assessed whether a primary care nurse-delivered complex intervention increased objectively measured step-counts and MVPA.

Methods and Findings

A total of 988 60–75 year olds, able to increase walking and randomly selected from three UK family practices, were invited to participate in a parallel two-arm cluster randomised trial; randomisation was by household. Two-hundred-ninety-eight people from 250 households were randomised between 2011 and 2012; 150 individuals to the intervention group, 148 to the usual care control group. Intervention participants received four primary care nurse physical activity (PA) consultations over 3 months, incorporating behaviour change techniques, pedometer step-count and accelerometer PA intensity feedback, and an individual PA diary and plan. Assessors were not blinded to group status, but statistical analyses were conducted blind. The primary outcome was change in accelerometry assessed average daily step-counts between baseline and 3 months, with change at 12 months a secondary outcome. Other secondary outcomes were change from baseline in time in MVPA weekly in ≥10-minute bouts, accelerometer counts, and counts/minute at 3 months and 12 months. Other outcomes were adverse events, anthropometric measures, mood, and pain. Qualitative evaluations of intervention participants and practice nurses assessed the intervention’s acceptability. At 3 months, eight participants had withdrawn or were lost to follow-up, 280 (94%) individuals provided primary outcome data. At 3 months changes in both average daily step-counts and weekly MVPA in ≥10-minute bouts were significantly higher in the intervention than control group: by 1,037 (95% CI 513–1,560) steps/day and 63 (95% CI 40–87) minutes/week, respectively. At 12 months corresponding differences were 609 (95% CI 104–1,115) steps/day and 40 (95% CI 17–63) minutes/week. Counts and counts/minute showed similar effects to steps and MVPA. Adverse events, anthropometry, mood, and pain were similar in the two groups. Participants and practice nurses found the intervention acceptable and enjoyable.

Conclusions

The PACE-Lift trial increased both step-counts and objectively measured MVPA in ≥10-minute bouts in 60–75 year olds at 3 and 12 months, with no effect on adverse events. To our knowledge, this is the first trial in this age group to demonstrate objective MVPA increases and highlights the value of individualised support incorporating objective PA assessment in a primary care setting.

Trial Registration

Controlled-Trials.com ISRCTN42122561     

Association of physical activity with lung function in lung-healthy German adults: results from the KORA FF4 study

Background

In lung disease, physical activity (PA) yields beneficial health effects, but its association with the function of healthy lungs has rarely been studied. We investigated the association of accelerometer-based PA with spirometric indices, maximal inspiratory mouth pressure (PI_max) and lung diffusion capacity in lung-healthy adults.

Methods

In total, 341 apparently lung-healthy participants from the population-based KORA (Cooperative Health Research in the Region of Augsburg) FF4 cohort study (45% male, aged 48-68 years, 47% never smokers) completed lung function testing and wore ActiGraph accelerometers over a one week period at the hip. In adjusted regression analyses, moderate to vigorous PA (MVPA) was characterized as: sex-specific activity quartiles, achieving ≥?10 consecutive minutes (yes vs. no), and meeting the WHO PA recommendations (yes vs. no).

Results

Positive associations of MVPA-quartiles with forced expiratory volume in 1 s (FEV₁), forced vital capacity (FVC), and corresponding Global Lung Function Initiative z-scores were found. Subjects in the most active quartile (>?47 or >?50 min/day for females and males, respectively) had 142 ml [95% CI: 23, 260] higher FEV₁ and 155 ml [95% CI: 10, 301] higher FVC than those in the least active quartile (<?17 or <?21 min/day for females and males, respectively); however these associations were stronger among ex?/current smokers. Achieving at least once 10 consecutive minutes of MVPA was only associated with higher PI_max [β-estimate: 0.57 kPa; 95% CI: 0.04, 1.10], remaining significant among never smokers. No associations were found with diffusion capacity or for reaching the WHO-recommended 150 min of MVPA/week in 10-min bouts.

Conclusions

Although the effects were small, active subjects showed higher spirometric results. The observed associations were more pronounced among ever smokers suggesting a higher benefit of PA for subjects being at a higher risk for chronic lung diseases.

     

Adherence to vitamin supplementation following adolescent bariatric surgery

Objective: Adolescents with extreme obesity, who have undergone bariatric surgery, must adhere to many lifestyle and nutritional recommendations, including multivitamin therapy. Little is known about multivitamin adherence following adolescent bariatric surgery. Design and Methods: The present study aims to document self‐reported and electronically‐monitored adherence to multivitamins, determine convergence between self‐report and electronic monitoring adherence for multivitamins, and identify barriers to multivitamin adherence for adolescents who have undergone bariatric surgery. Results: The study used a prospective, longitudinal observational design to assess subjective (self‐reported) and objective (electronic monitors) multivitamin adherence in a cohort of 41 adolescents (Mean age = 17.1 ± 1.5; range = 13‐19) who have undergone bariatric surgery at Cincinnati Children's Hospital Medical Center. Mean adherence as derived from electronic monitoring for the entire 6‐month study period was 29.8% ± 23.9. Self‐reported adherence was significantly higher than electronically monitored adherence across both the 1 and 6‐month assessment points (z = 4.5, P < 0.000 and z = 4.0, P < 0.0001, respectively). Forgetting and difficulty swallowing multivitamins were the two primary barriers identified. While there are no established data regarding best practice for multivitamins following bariatric surgery, high rates of nonadherence to multivitamin therapy were observed in adolescents who had undergone bariatric surgery with forgetting and difficulty swallowing pills as reported barriers to adherence. Conclusion: These high rates of nonadherence to multivitamin therapy should be considered when devising treatment and family education pathways for adolescents considering weight loss surgery.     

Sedentary behavior, recreational physical activity, and 7-year weight gain among postmenopausal U.S. women

Objective: To assess the relationship among recreational physical activity (PA), non‐occupational sedentary behavior, and 7‐year weight gain among postmenopausal U.S. women 40 to 69 years old. Research Methods and Procedures: In 1992 and 1999, 18,583 healthy female participants from the Cancer Prevention Study II Nutrition Cohort completed questionnaires on anthropometric characteristics and lifestyle factors. The associations between recreational PA [in metabolic equivalent (MET) hours per week] and non‐occupational sedentary behavior (in hours per day) at baseline and risk for 7‐year weight gain (5 to 9 or ≥10 vs. ±4 pounds) were assessed using multivariate logistic regression analysis. Results: Neither PA nor sedentary behavior was associated with a 5‐ to 9‐pound weight gain. Among women who were not overweight at baseline (BMI <25.0), the odds of ≥10‐pound weight gain were 12% lower (odds ratio, 0.88; 95% confidence interval, 0.77 to 0.99) for those in the highest category of recreational PA (≥18 MET h/wk) compared with >0 to <4 MET h/wk; odds were 47% higher (odds ratio, 1.47; 95% confidence interval, 1.21 to 1.79) for non‐overweight women who reported ≥6 h/d of non‐occupational sedentary behavior compared with <3 h/d. Neither PA nor sedentary behavior were associated with risk of ≥10‐pound weight gain weight among women who were overweight at baseline (BMI ≥25.0). Discussion: Both recreational PA and non‐occupational sedentary behavior independently predicted risk of ≥10‐pound weight gain among postmenopausal women who were not overweight at baseline. Public health messages to prevent weight gain among normal‐weight postmenopausal women may need to focus on decreasing time spent in sedentary behaviors and increasing the amount of time spent on PA.     

Effects of weight status and barriers on physical activity adoption among previously inactive women

This study examined self‐reported physical activity (PA) barriers, and their effects on PA behavior change at 3 and 12 months among 280 previously inactive women enrolled in a PA promotion trial. Effect modification of baseline barriers by baseline weight status on PA behavior change was also examined. At baseline and month 12, obese women reported significantly greater PA barriers compared with normal and overweight women (P < 0.05). Individual barriers that were more likely to be elevated for obese vs. normal and overweight participants at baseline were feeling too overweight, feeling self‐conscious, reporting minor aches and pains, and lack of self‐discipline. Also, weight status moderated the effect of PA barriers on PA behavior change from baseline to month 3 (P < 0.05), but not to month 12 (P = 0.637), with obese participants reporting high barriers achieving 70 min/week fewer than those with low barriers (P < 0.05). Finally, the interaction between barriers (high vs. low) and weight status (obese vs. normal), shows PA barriers had a detrimental PA effect among obese participants that was 122.5 min/week (95% confidence interval (CI) = 15.7, 229.4; P < 0.05) lower than their effect on normal‐weight participants. These results suggest that for obese women, PA barriers have quantifiable effects on PA behavior change. This study has implications for the design of future weight loss and PA interventions, suggesting that a comprehensive assessment of PA barriers is a prerequisite for appropriate tailoring of behavioral PA interventions.     

Weight Loss Intervention for Obese Older Women: Improvements in Performance and Function

Objectives: To determine the feasibility of a 3‐month weight loss program for obese older women with short‐term laboratory, performance, functional, and life quality outcomes. Research Methods and Procedures: This was a pre‐ and postintervention design. Community‐dwelling women (n = 26) ≥60 years old with BMI ≥30 were enrolled in a 3‐month weight loss program promoting prudent diet, behavior modification, and physical activity. The primary emphasis of the program was on health, function, and quality of life. The approach was specifically tailored to older subjects through use of large‐font instructional materials, supplementation of calcium and vitamin D, and moderate weight loss and physical activity goals. An initial assessment by a bariatric physician was followed by eight visits with a dietitian and a follow‐up physician visit. Measurements included anthropometrics, body composition, laboratories, pedometer, physical performance, Short‐Form 36 Health Status Survey (SF‐36), Life Space Assessment, and dietary assessment. Results: Eighteen participants completed the program. There was a significant decrease in mean body weight (100 ± 15 vs. 96 ± 18 kg, p = 0.006), with a mean weight loss of 4.3 ± 5.5 kg (range ?15.5 to +7.20 kg). Significant improvements were observed for diastolic blood pressure, total cholesterol, triglycerides, physical performance, pedometer‐measured step counts, and step climb and descent. Self‐rated physical functioning (SF‐36 subscore) and vitality (SF‐36 subscore) were also significantly improved. Discussion: It is feasible for self‐selected obese older women to achieve a moderate weight loss and increase in physical activity resulting in short‐term improvements in laboratory, physical performance, self‐reported function, vitality, and life quality outcomes.     

Post‐Exercise Blood Pressure Reduction Is Greater Following Intermittent Than Continuous Exercise and Is Influenced Less by Diurnal Variation

Recently, we reported that circadian variation exists in the response of blood pressure (BP) following a bout of uninterrupted exercise. The usual phenomenon of post‐exercise hypotension was absent or reversed when such exercise was performed between 04:00–08:00 h. Nevertheless, research examining BP changes following bouts of intermittent exercise at different times of the day is scarce, even though this type of activity is probably more popular. Therefore, we aimed to compare post‐exercise BP reductions of continuous (CONT) and intermittent (INT) exercise protocols performed at 08:00 h and 16:00 h. At both of these times of day, eight normotensive males completed 30 min of continuous cycling in the CONT and three 10 min bouts of cycling separated by 10 min of rest in the INT protocol. The exercise intensity was set at 70% V˙O_2peak during both protocols. Heart rate, systolic (S) and diastolic (D) BP, and mean arterial pressure (MAP) were measured 5 min before and 20 min after exercise. Changes from pre‐exercise baseline were analyzed using linear mixed modeling. MAP was 8±1 mm Hg lower following INT compared with CONT exercise (p<0.05). SBP and DBP were also significantly lower following INT compared with CONT exercise (p<0.05). Diurnal variation in MAP was evident, with attenuated hypotension being observed after morning exercise (p<0.05), although this diurnal variation was less marked following INT compared with CONT exercise (p<0.05). We conclude that intermittent exercise mediates greater post‐exercise hypotension compared with a single continuous bout of equivalent work and that this protocol‐dependent difference is greatest in the afternoon. Therefore, a bout of afternoon exercise that is occasionally interrupted with short rest periods is recommended for lowering BP acutely.     

Selenium supplementation and exercise: effect on oxidant stress in overweight adults

Both obesity and acute high‐intensity exercise increase oxidant stress levels. This study investigates whether selenium (Se) supplementation could be a potential effective therapy to reduce obesity‐associated oxidant stress and exercise‐induced oxidant stress. Ten normal‐weight (NW) (22.80 ± 0.41 kg/m²) and ten overweight (OW) healthy subjects (28.00 ± 0.81 kg/m²) were assessed during a randomized double‐blind Se supplementation study (200 µg sodium selenite/day for 3 weeks) with a 3‐week placebo control and inversion of treatment periods. Blood levels of lipid hydroperoxide (LH), superoxide dismutase (SOD), erythrocyte glutathione (GSH), and total antioxidant status (TAS), were measured at rest, pre‐, and postexercise (30 min 70% VO₂ max before and after treatment (pretreatment (week 0 and 12) and post‐treatment (week 3 or 15)). At rest, compared to placebo, Se supplementation had no significant effect on LH, SOD, GSH, and TAS levels. However, Se supplementation decreased LH levels in the OW group, immediately postexercise (?0.25 ± 0.12 µmol/l, P = 0.05) compared to placebo treatment. Postexercise, with or without Se supplementation, no changes in TAS, SOD, and GSH levels were observed in both the NW and OW group. This study has highlighted a potential benefit of Se in reducing LH levels postexercise in OW individuals. Given that oxidant stress is a predictor of coronary events, it is imperative to better understand oxidant stress‐related responses to lifestyle factors (in particular “high‐risk” population groups) and potential antioxidant therapy.     

Consistent self-monitoring of weight: a key component of successful weight loss maintenance

Objective: The objectives were to investigate the characteristics associated with frequent self‐weighing and the relationship between self‐weighing and weight loss maintenance. Research Methods and Procedures: Participants (n = 3003) were members of the National Weight Control Registry (NWCR) who had lost ≥30 lbs, kept it off for ≥1 year, and had been administered the self‐weighing frequency assessment used for this study at baseline (i.e., entry to the NWCR). Of these, 82% also completed the one‐year follow‐up assessment. Results: At baseline, 36.2% of participants reported weighing themselves at least once per day, and more frequent weighing was associated with lower BMI and higher scores on disinhibition and cognitive restraint, although both scores remained within normal ranges. Weight gain at 1‐year follow‐up was significantly greater for participants whose self‐weighing frequency decreased between baseline and one year (4.0 ± 6.3 kg) compared with those whose frequency increased (1.1 ± 6.5 kg) or remained the same (1.8 ± 5.3 kg). Participants who decreased their frequency of self‐weighing were more likely to report increases in their percentage of caloric intake from fat and in disinhibition, and decreases in cognitive restraint. However, change in self‐weighing frequency was independently associated with weight change. Discussion: Consistent self‐weighing may help individuals maintain their successful weight loss by allowing them to catch weight gains before they escalate and make behavior changes to prevent additional weight gain. While change in self‐weighing frequency is a marker for changes in other parameters of weight control, decreasing self‐weighing frequency is also independently associated with greater weight gain.     

Rectal temperatures before and after parturition in bottlenose dolphins

In five parturitions of four bottlenose dolphins (Tursiops truncatus gilli), rectal temperatures (Rts) were determined at least once a day during the late period of pregnancy. Four of the five pregnancies showed a drop in RT ranging from 0.7 to 1.3°C (an average decrease of 0.9°C) from 24 to 12 hr pre‐partum. In these four cases, RT was significantly lower than their averages from 10 days to 1 day pre‐partum (P < 0.05). In two dolphins, the first RT post‐partum was higher than the average RT from 10 days to 1 day pre‐partum. Seasonal changes in RT were observed in six non‐pregnant dolphins. Average RT in June through August was significantly higher and in December through February was significantly lower than the rest of the year (P < 0.01). Zoo Biol 18:153–156, 1999. © 1999 Wiley‐Liss, Inc.     

Moderate Intense Physical Activity Depends on Selected Metabolic Equivalent of Task (MET) Cut-Off and Type of Data Analysis

Background

Accelerometry data are frequently analyzed without considering whether moderate-to-vigorous physical activities (MVPA) were performed in bouts of >10 minutes as defined in most physical activity guidelines. We aimed i) to quantify MVPA by using different commonly-applied physical activity guidelines, ii) to investigate the effect of bouts versus non-bouts analysis, and iii) to propose and validate a MVPA non-bouts cut-point to classify (in-) active subjects.

Methods

Healthy subjects (n=110;62±6yrs) and patients with Chronic Obstructive Pulmonary Disease (COPD) (n=113;62±5yrs) wore an activity monitor for 7 days. Three Metabolic Equivalent of Task (MET) cut-offs and one individual target (50% VO₂ reserve) were used to define MVPA. First, all minutes of MVPA were summed up (NON-BOUTS). Secondly, only minutes performed in bouts of >10 minutes continuous activity were counted (BOUTS). Receiver operating characteristic (ROC) curve analyses were used to propose and (cross-) validate new MVPA non-bout cut-points based on the criterion of 30 minutes MVPA per day (BOUTS). Likelihood ratios (sensitivity/[1-specificity]) were used to express the association between the proposed MVPA non-bout target and the MVPA bout target of 30 min*day^-1.

Results

MVPA was variable across physical activity guidelines with lowest values for age-specific cut-offs. Selecting a METs cut-point corresponding to 50% VO₂ reserve revealed no differences in MVPA between groups. MVPA’s analyzed in BOUTS in healthy subjects were 2 to 4 fold lower than NON-BOUTS analyses and this was even 3 to 12 fold lower in COPD. The MVPA non-bouts cut-point of 80 min*day^-1 using a 3 METs MVPA threshold delivered positive likelihood ratios of 5.1[1.5-19.6] (healthy subjects) and 2.3[1.6-3.3] (COPD).

Conclusion

MVPA varies upon the selected physical activity guideline/targets and bouts versus non-bouts analysis. Accelerometry measured MVPA non-bouts target of 80 min*day^-1, using a 3 METs MVPA threshold, is associated to the commonly-used MVPA bout target of 30 min*day^-1.     

Reduction of 8-iso-prostaglandin F2α in the first week after Roux-en-Y gastric bypass surgery

Obesity is associated with increased markers of oxidative stress. We examined whether oxidative stress is reduced within the first week after Roux‐en‐Y gastric bypass (RYGB) surgery and could be related to changes in adipose tissue depots. The reactive oxygen species (ROS) marker 8‐iso‐prostaglandin F2α (8‐iso‐PGF2α) and activity of antioxidant glutathione peroxidases (GPX) in plasma were compared before and ～1 week after RYGB. The effects of RYGB on subcutaneous adipose tissue and interstitial fluid 8‐iso‐PGF2α levels and subcutaneous adipose tissue expression of GPX‐3 were also assessed. Levels of 8‐iso‐PGF2α in subcutaneous and visceral adipose tissue were determined. Plasma 8‐iso‐PGF2α levels decreased (122 ± 75 to 56 ± 15 pg/ml, P = 0.001) and GPX activity increased (84 ± 18 to 108 ± 25 nmol/min/ml, P = 0.003) in the first week post‐RYGB. RYGB also resulted in reductions of 8‐iso‐PGF2α in subcutaneous adipose tissue (1,742 ± 931 to 1,132 ± 420 pg/g fat, P = 0.046) and interstitial fluid (348 ± 118 to 221 ± 83 pg/ml, P = 0.046) that were comparable to plasma (26–33%, P = 0.74). Adipose GPX‐3 expression was increased (6.7 ± 4.7‐fold, P = 0.004) in the first postoperative week. The improvements in oxidative stress occurred with minimal weight loss (2.4 ± 3.4%, P = 0.031) and elevations in plasma interleukin‐6 (18.0 ± 46.8 to 28.0 ± 58.9 pg/ml, P = 0.004). Subcutaneous and visceral adipose tissues express comparable 8‐iso‐PGF2α levels (1,204 ± 470 and 1,331 ± 264 pg/g fat, respectively; P = 0.34). These data suggest that RYGB affects adipose tissue leading to the restoration of adipose redox balance within the first postoperative week and that plasma 8‐iso‐PGF2α is primarily derived from subcutaneous adipose tissue.