Interactions between a polygenic risk score for plasma docosahexaenoic fatty acid concentration, eating behaviour, and body composition in children.

BACKGROUND: The relationship between eating behaviour and current body weight has been described. However little is known about the effect of polyunsaturated fatty acids (PUFA) in this relationship. Genetic contribution to a certain condition is derived from a combination of small effects from many genetic variants, and polygenic risk scores (PRS) summarize these effects. A PRS based on a GWAS for plasma docosahexaenoic fatty acid (DHA) has been created, based on SNPs from 9 genes. OBJECTIVE: To analyze the interaction between the PRS for plasma DHA concentration, body composition and eating behaviour (using the Children Eating Behaviour Questionnaire) in childhood. SUBJECTS/METHODS: We analyzed a subsample of children from the Maternal, Adversity, Vulnerability and Neurodevelopment (MAVAN) cohort with PRS and measurements of eating behaviour performed at 4 years of age (n = 210), 6 y (n = 177), and body fat determined by bioelectric impedance at 4 y and 6 y or by air displacement plethysmography and dual-energy X-ray absorptiometry at 8 y (n = 42 and n = 37). PRS was based on the GWAS from Lemaitre et al. 2011 (p threshold = p < 5*10-6), and a median split created low and high PRS groups (high PRS = higher DHA level). RESULTS: In ALSPAC children, we observed an association between PRS and plasma DHA concentration (ß = 0.100, p < 0.01) and proportion (ß = 0.107, p < 0.01). In MAVAN, there were interactions between PRS and body fat on pro-intake scores in childhood, in which low PRS and higher body fat were linked to altered behaviour. There were also interactions between PRS and pro-intake scores early in childhood on body fat later in childhood, suggesting that the genetic profile and eating behaviour influence the development of adiposity at later ages. CONCLUSIONS: A lower PRS (lower plasma PUFA) can be a risk factor for developing higher body fat associated with non-adaptive eating behaviour in childhood; it is possible that the higher PRS (higher plasma PUFA) is a protective feature.

Participation in and outcomes from a 12-month tailored exercise programme for people with multiple sclerosis (MSTEP©): a randomized trial.

OBJECTIVE: To estimate, among people with multiple sclerosis, the extent to which a personally tailored exercise programme (MSTEP©) resulted in greater improvements in exercise capacity and related outcomes over 12 months in comparison with general exercise guidelines. DESIGN: Two-group randomized trial. SUBJECTS: Ambulatory and sedentary. INTERVENTIONS: MSTEP©, a personally adapted exercise regimen done on most days including two days of high intensity exercise; guidelines recommending 30 minutes of moderate intensity aerobic and strength training two times per week. MAIN MEASURES: Primary outcome was peak oxygen consumption (VO2peak) at 12 months; secondary outcomes were composite measures of physical function, fatigue, and health-related quality of life. RESULTS: In total, 137 people were randomized, 66 were lost over 12 months leaving 71 with outcome data, 34 in MSTEP© group, and 37 in the Guideline group. Exercise enjoyment and confidence and exercise-induced fatigue predicted retention. There were no differences between groups on the proportion making a 10% increase in VO2peak (27.1% MSTEP© vs 29.6% Guidelines; OR: 0.83; 95% CI: 0.23-3.08) by the 12 month assessment. The effect on fatigue was larger in the MSTEP© group than the Guideline groups (OR: 1.59; 95% CI: 0.93-2.74), the effect on physical function was more modest (OR: 1.35; 95% CI: 0.80-2.25), and null for health-related quality of life outcomes. CONCLUSIONS: The disappointing exercise retention suggests that people with multiple sclerosis may not consider exercise important to their brain health. Either type of exercise resulted in stable exercise capacity over 1 year in those sticking with the programme.

Seasonal Changes in Physiological Responses and Body Composition During a Competitive Season in Male and Female Elite Collegiate Ice Hockey Players.

Delisle-Houde, P, Reid, RER, Insogna, JA, Chiarlitti, NA, and Andersen, RE. Seasonal changes in physiological responses and body composition during a competitive season in male and female elite collegiate ice hockey players. J Strength Cond Res 33(8): 2162-2169, 2019-Ice hockey continually overloads athletes with limited time for recovery, which may affect several physiological responses and alter body composition. The purpose of this study was to identify changes in physiological parameters and body composition profiles over the competitive season in elite collegiate ice hockey players. Forty-four players, 24 males (age = 22.7 ± 1.3 years, height = 1.82 ± 0.6 m, and body mass = 86.87 ± 6.44 kg) and 20 females (age = 19.9 ± 1.8 years, height = 1.66 ± 0.7 m, and body mass = 68.76 ± 5.91 kg) participated in 4-minute submaximal exercise tests and body composition assessments at pre-season, mid-season, and end-season. Changes in physiological parameters and body composition were analyzed using repeated-measures analysis of covariance controlling for age. Males' postexercise blood lactate concentration decreased (p ≤ 0.05) from pre- to mid-season (9.3 vs. 6.2 mmol·L) and increased (p ≤ 0.05) from mid- to end-season (6.2 vs. 8.0 mmol·L). Heart rate increased (p ≤ 0.05) after the third and fourth minute of the submaximal test in both sexes from pre- to end-season and from mid- to end-season. Males' body fat percentage decreased (p ≤ 0.05) from mid-season (17.4 vs. 16.1%), whereas increases were observed (p ≤ 0.05) in both sexes from mid- to end-season. This study produced evidence that male and female collegiate hockey athletes' physiological responses and body composition profiles change over the season. Sport scientists working with collegiate hockey teams, may need to revise annual training programs to attenuate reductions in fitness and hopefully prevent injuries.

Comparing DXA and Air Displacement Plethysmography to Assess Body Composition of Male Collegiate Hockey Players.

Delisle-Houde, P, Reid, RER, Insogna, JA, Prokop, NW, Buchan, TA, Fontaine, SL, and Andersen, RE. Comparing DXA and air-displacement-plethysmography to assess body composition of male collegiate hockey players. J Strength Cond Res 33(2): 474-478, 2019-Accurate assessment of body composition is an important consideration for athletes because it is a health/performance variable. However, little is known about the variability in values obtained across different assessment methods for specific athlete populations. The purpose of this study was to compare 2 common laboratory methods that assess body composition: air displacement plethysmography (BOD POD) and dual energy x-ray absorptiometry (DXA). Twenty-nine male collegiate hockey players, (Age = 24.07 ± 1.49, BMI = 26.5 ± 2.74) participated in this study. All participants underwent back-to-back BOD POD and DXA evaluations. Paired t-tests and Bland-Altman analyses were performed to compare differences in fat mass, fat percentage, and fat-free mass between methods. Average fat percentage reported by the DXA and BOD POD was 15.34 ± 3.53 and 11.66 ± 4.82 respectively, resulting in a bias score of 3.78 ± 2.33 kg (t(28) = 8.71, p ≤ 0.001). Average fat mass reported by the DXA and BOD POD was 13.42 ± 3.59 and 10.15 ± 4.54 kg respectively, resulting in a bias score of 3.27 ± 1.92 kg (t(28) = 9.18, p ≤ 0.001). Average fat-free mass reported by the DXA and BOD POD was 73.31 ± 5.30 and 76.25 ± 5.74 kg respectively, resulting in a bias score of -2.93 ± 2.06 kg (t(28) = -7.66, p ≤ 0.001). Our findings can help make more insightful comparisons between studies that use different body composition methodologies among athletic populations.

Longitudinal Changes in Body Composition Throughout Successive Seasonal Phases Among Canadian University Football Players.

Kim, J, Delisle-Houde, P, Reid, RER, and Andersen, RE. Longitudinal changes in body composition throughout successive seasonal phases among Canadian university football players. J Strength Cond Res 32(8): 2284-2293, 2018-The purpose of this study was to assess changes in body composition during seasonal phases of the training year among Canadian Inter-University Sport (CIS) football players. Forty university football players were assessed for anthropometry, total body composition, regional body composition, and central adiposity over a 7-month period including the summer off-season and the in-season. Baseline testing occurred in April, before the summer off-season, and follow-ups were completed before training camp, at the beginning of August, and following the in-season, at the beginning of November. Linemen had the greatest tissue percent fat (25.98 ± 6.56%) at baseline, significantly (p < 0.01) greater than big skill (18.69 ± 3.97%) and followed by skill (14.35 ± 3.39%) who were significantly (p < 0.01) leaner than both other groups. Skill players significantly increased fat mass (0.98 ± 0.30 kg, p ≤ 0.05) and waist-to-hip ratio (0.02 ± 0.01, p ≤ 0.05) during the in-season, and linemen increased visceral fat mass from April to November (0.20 ± 0.06 kg, p ≤ 0.01). All players significantly (-1.26 ± 0.30 kg, p = 0.001) decreased lean mass during the in-season. All groups significantly increased bone mineral content during the summer off-season (p ≤ 0.05). There was also a significant time × summer training location interaction (p ≤ 0.05) for fat mass with athletes who remained on campus during summer months gaining the least amount of adiposity. Body composition and central adiposity seem to change differentially among positional groups across the annual training season.

Relationship Between Physiologic Tests, Body Composition Changes, and On-Ice Playing Time in Canadian Collegiate Hockey Players.

Delisle-Houde, P, Chiarlitti, NA, Reid, RER, and Andersen, RE. Relationship between physiologic tests, body composition changes, and on-ice playing time in canadian collegiate hockey players. J Strength Cond Res 32(5): 1297-1302, 2018-Hockey player's body composition and physical fitness are suggested to influence coaching decisions regarding on-ice playing time. The purpose of this study was to explore the relationship between seasonal body composition changes, off-ice preseason testing, and on-ice metrics. Twenty-one Canadian collegiate hockey players (22.70 ± 1.30 years old, 181.0 ± 5.92 cm, 86.52 ± 6.41 kg) underwent off-ice physical testing at the beginning of their season and had one total body dual energy x-ray absorptiometry scan at the beginning and end of the season. The team's statistician tracked all on-ice metrics. Pearson correlations were used to explore relationships between off-ice tests (long jump, vertical jump, beep test, and Wingate test), change in body composition (body fat percentage, visceral adiposity, and total lean tissue mass), and on-ice performance (average time on ice, average shift length, power play time, penalty kill time, and shot differential). Long jump was correlated with shot differential (r = -0.532, p ≤ 0.05) and average shift length (r = -0.491, p ≤ 0.05) while fatigue index was correlated with average ice time (r = -0.476, p ≤ 0.05). Hockey performance is a complex interaction of player's body compositions and skeletal fitness that interact to affect on-ice playing metrics.

Importance of Body Composition in the National Hockey League Combine Physiological Assessments.

Chiarlitti, NA, Delisle-Houde, P, Reid, RER, Kennedy, C, and Andersen, RE. Importance of body composition in the national hockey league combine physiological assessments. J Strength Cond Res 32(11): 3135-3142, 2018-The National Hockey League (NHL) combine was designed to assess draft-eligible players based on body composition, speed, power, and strength. The importance of body composition in the battery of combine physical tests was investigated, and differences in results based on position were explored. Thirty-seven elite male Canadian university hockey players (age = 22.86 ± 1.55 years, mass = 87.21 ± 6.52 kg, and height = 181.69 ± 6.19 cm) participated in the study at the beginning of their hockey season. All participants underwent physical testing (as outlined in the 2016 NHL combine) and 1 total body dual energy x-ray absorptiometry scan to measure body composition. Partial correlations (controlling for body mass) were used to explore the relationship among body composition measures (body fat percentage, visceral fat, body mass index, lower lean tissue mass, upper lean tissue mass, upper fat mass, and lower fat mass) with NHL fitness tests (bench press, pull-ups, grip strength, long jump, proagility, vertical jump, V[Combining Dot Above]O2max, and the Wingate Anaerobic Test). In 4 of the 6 strength/power tests (Wingate Anaerobic Test, long jump, bench press, and both grip strengths), lower and upper lean tissue mass explained significant amounts of variance. Although forwards and defensemen significantly differed in right grip strength and proagility left scores, they did not differ in regard to any body composition variables. Body composition has a significant influence on several combine-specific tests, which may help sport scientists and strength and conditioning coaches to better tailor training programs and to optimize performance in elite hockey players.

Accuracy of two Generic Prediction Equations and One Population-Specific Equation for Resting Energy Expenditure in Individuals with Spinal Cord Injury.

PURPOSE: The primary aim was to assess the accuracy of common prediction equations, the Harris-Benedict (HB) and the Mifflin St. Jeor (MSJ) equations, for estimating resting energy expenditure (REE) among people with spinal cord injury (SCI) against actual REE measurements. The secondary aim was to cross-validate the Buchholz et al. energy prediction equation created for people with SCI. METHODS: A metabolic cart with canopy was used to measure the actual REE. The HB, MSJ, and the Buchholz et al. equations were used for the prediction of REE. RESULTS: Thirty-nine participants (31 males and 8 females) were enrolled in this cross-sectional study. The REEs significantly differed from one another, F(1.52, 57.68) = 52.04, P < 0.001, where both the HB (M = 1703.06, SD = 265.1) and the MSJ (M = 1628.92, SD = 233.8) energy predictions were significantly higher (P < 0.001) than the measured REE (M = 1394.05, SD = 298.7). In contrast, the Buchholz et al. equation did not differ from the measured REE. CONCLUSIONS: Our data show that the HB and MSJ equations do not accurately predict the energy needs of this community. Using a SCI-specific equation would improve estimates of REE, such as the Buchholz et al. equation. More research into energy equations for this population may help health care professionals better tailor dietary requirements for weight management.

Seasonal Changes in Whole Body and Regional Body Composition Profiles of Elite Collegiate Ice-Hockey Players.

The monitoring of a collegiate hockey player's body composition can reflect fitness characteristics and may help players, coaches, or strength and conditioning specialists optimize physiologic gains during an off-season, whereas simultaneously preventing performance decrements in-season. The purpose of the study was to investigate changes in whole-body and regional-body composition of fat and lean tissue. The body composition profiles of 19 elite Canadian collegiate hockey players were assessed using dual energy X-ray absorptiometry. Players completed end-of-season, preseason, and midseason assessments with questionnaires relating to their off-season and in-season training. Statistically significant changes in body composition profiles were observed between the different time points because players showed various tissue gains and losses depending on the region assessed. Overall, players gained (1.38 kg, p ≤ 0.01) and lost (0.79 kg, p ≤ 0.01) fat tissue during the off-season and in-season, respectively. Players also showed a significant gain of leg lean tissue (0.29 kg, p = 0.02) and loss of arm tissue mass (-0.25 kg, p = 0.02) during the first-half of the competitive season. Several correlations emerged that may provide insight into potential trends that could be more pronounced during longer and more demanding schedules. Collegiate hockey players show changes in body composition during the off-season and in-season. The understanding of body composition profiles, body composition fluctuations, and potential variables that may influence the composition of collegiate hockey players can help coaches and athletic programs tailor their team's training, nutrition, lifestyle, and informative resources to further support their athletes.

Energy Intake and Food Habits between Weight Maintainers and Regainers, Five Years after Roux-en-Y Gastric Bypass.

We explored differences in dietary behaviours, energy, and macronutrient intake among individuals who had regained or maintained weight loss 5 or more years after Roux-en-Y gastric bypass (RYGB). This study assessed 27 adults who underwent RYGB an average of 12.1 ± 3.7 years before this study was conducted. Dietary assessment was performed using 3-day food records. Daily energy intake (kcal), protein (g), carbohydrate (g), fat (g), and alcohol intake (g) were computed using the ESHA's Food Processor®. Participants were classified by percent weight loss, maintainers (≥38 %), and regainers (≤30 %). Daily carbohydrate consumption was greater in regainers (222 ± 84.3 g) compared with maintainers (162 ± 67.5 g), (P < 0.05). Thirty-seven percent of participants were not consuming the recommended amount of protein and 26% reported never taking vitamin supplements after surgery. Alcohol consumption was higher among regainers (18.5 ± 30.9 g) compared with maintainers (2.6 ± 6.5 g), (P < 0.05). Finally, 74% of the participants reported no contact with a Registered Dietitian, whereas 78 % were in contact with a health care professional once a year post-surgery. Differences were seen in carbohydrate intake and alcohol consumption between weight maintainers and regainers. These data suggest dietitians need to play a more active role in the long-term care of this medically complex population.

Physiological mechanisms of sex differences in exertional dyspnoea: role of neural respiratory motor drive.

NEW FINDINGS: What is the central question of this study? Does the combination of a higher neural respiratory drive and greater dynamic mechanical ventilatory constraints during exercise in healthy women versus men form the mechanistic basis of sex differences in activity-related dyspnoea? What is the main finding and its importance? Sex differences in activity-related dyspnoea in health primarily reflected the awareness of a higher neural respiratory drive needed to achieve any given ventilation during exercise in the setting of relatively greater dynamic mechanical ventilatory constraints in women. These findings may have implications for our understanding of the mechanisms of sex differences in exertional dyspnoea in variants of health (e.g. the elderly) and in patients with cardiorespiratory disease. The purpose of this study was to elucidate the physiological mechanisms of sex differences in exertional dyspnoea. We compared detailed measures of neural respiratory motor drive [diaphragmatic EMG (EMGdi) expressed as a percentage of maximal EMGdi (EMGdi%max)], breathing pattern, operating lung volumes, dynamic respiratory mechanics [tidal oesophageal (P(oes,tida)l%peak) and transdiaphragmatic pressure swings (P(di,tidal)%peak) expressed as a percentage of their respective peak values] and sensory intensity and unpleasantness ratings of dyspnoea during symptom-limited incremental cycle exercise in healthy young women (n = 25) and men (n = 25). The tidal volume to forced vital capacity ratio (V(T)%FVC), breathing frequency, EMGdi%max, P(oes,tidal)%peak, P(di,tidal)%peak and sensory intensity and unpleasantness ratings of dyspnoea were higher, while dynamic inspiratory capacity and inspiratory reserve volume were lower at a standardized absolute ventilation of 55 l min(-1) during submaximal exercise in women versus men (all P < 0.05). In contrast, sex had no demonstrable effect on the inter-relationships between exercise-induced increases in V(T)%FVC, EMGdi%max and sensory intensity and unpleasantness ratings of dyspnoea. The results of this study suggest that sex differences in the intensity and unpleasantness of exertional dyspnoea in health are likely to reflect the awareness of a relatively higher neural respiratory motor drive (or EMGdi%max) needed to achieve any given ventilation during exercise in the setting of relatively greater dynamic mechanical constraints on V(T) expansion in women.

In vivo precision of the GE lunar iDXA for the assessment of lumbar spine, total hip, femoral neck, and total body bone mineral density in severely obese patients.

No study has evaluated the precision of the GE Lunar iDXATM (GE Healthcare) in measuring bone mineral density (BMD) among severely obese patients. The purpose of the study was to evaluate the precision of the GE Lunar iDXATM for assessing BMD, including the lumbar spine L1-L4, L2-L4, the total hip, femoral neck, and total body in a severely obese population (body mass index [BMI]>40 kg/m(2)). Sixty-four severely obese participants with a mean age of 46 ± 11 yr, BMI of 49 ± 6 kg/m(2), and a mean body mass of 136.8 ± 20.4 kg took part in this investigation. Two consecutive iDXA scans (with repositioning) of the total body (total body BMD [TBBMD]), lumbar spine (L1-L4 and L2-L4), total hip (total hip BMD [THBMD]), and femoral neck (femoral neck BMD [FNBMD]) were conducted for each participant. The coefficient of variation (CV), the root mean square (RMS) averages of standard deviations of repeated measurements, the corresponding 95% least significant change, and intraclass correlations (ICCs) were calculated. In addition, analysis of bias and coefficients of repeatability were calculated. The results showed a high level of precision for total body (TBBMD), lumbar spine (L1-L4), and total hip (THBMD) with values of RMS: 0.013, 0.014, and 0.011 g/cm(2); CV: 0.97%, 1.05%, and 0.99%, respectively. Precision error for the femoral neck was 2.34% (RMS: 0.025 g/cm(2)) but still represented high reproducibility. ICCs in all dual-energy X-ray absorptiometry measurements were 0.99 with FNBMD having the lowest at 0.98. Coefficients of repeatability for THBMD, FNBMD, L1-L4, L2-L4, and TBBMD were 0.0312, 0.0688, 0.0383, 0.0493, and 0.0312 g/cm(2), respectively. The Lunar iDXA demonstrated excellent precision for BMD measurements and is the first study to assess reproducibility of the GE Lunar iDXA with severely obese adults.

A single-armed proof-of-concept study of Lymfit: A personalized, virtual exercise intervention to improve health outcomes in lymphoma survivors in the pandemic.

BACKGROUND AND OBJECTIVE: Treatments of lymphoma can lead to reduced physical functioning, cancer-related fatigue, depression, anxiety, and insomnia. These side effects can negatively impact the cancer survivor's quality of life. Mounting evidence indicates that physical activities are highly therapeutic in mitigating the short- and long-term side effects of cancer treatments. Yet, lymphoma survivors' participation in physical activities remains suboptimal, which has been further exacerbated by the deleterious effects of isolation during the COVID-19 pandemic. The Lymfit intervention aims to offer motivational support, expert guidance, and a personalized exercise prescription to optimize physical activities among lymphoma survivors. This proof-of-concept study explores implementation feasibility (retention, technical and safety), and the preliminary effects of Lymfit on various health outcomes. METHOD: This was a single-armed trial with a pre-and post-test design. Twenty lymphoma survivors were recruited to participate in the 12-week Lymfit intervention. Wearable activity trackers (Fitbit) were given to participants as a motivational tool and for data collection purposes. Participants received a personalized exercise prescription designed by a kinesiologist. Physiologic metrics were collected by the Fitbit monitors and were stored in the Lymfit database. Self-reported questionnaires measuring health outcomes were collected at baseline and post-intervention. RESULTS: The retention rate of this trial was 70%. Minimal technical issues and no adverse effects were reported. Lymfit led to significant improvements in sleep disturbances and the ability to participate in social activities and decreased fear of cancer recurrence. It also increased daily steps and decreased sedentary time in participants who did not meet the recommended physical activity guidelines. SIGNIFICANCE: With access to resources and fitness centers being limited during the pandemic, the Lymfit intervention filled an immediate need to provide physical activity guidance to lymphoma survivors. Findings provide preliminary support that implementing the Lymfit intervention is feasible and demonstrated promising results.

Pilot Randomized Controlled Trial of Lymfit: A Theory-Guided Exercise Intervention for Young Adults with Lymphoma.

Despite the rapidly emerging evidence on the contributions of physical activity to improving cancer-related health outcomes, adherence to physical activity among young adults with lymphoma remains suboptimal. Guided by self-determination theory (SDT), the Lymfit intervention (a 12-week individualized exercise program with bi-weekly kinesiologist support and an activity tracker) aimed to foster autonomous motivation toward physical activity. This pilot randomized controlled trial aimed to evaluate the feasibility, acceptability, and preliminary effects of Lymfit. Young adults (N = 26; mean age of 32.1 years) with lymphoma who were newly diagnosed and those up to six months after completing treatment were recruited and randomly assigned one-to-one to either the intervention group (n = 13) or a wait-list control group (n = 13). All a priori feasibility benchmarks were met, confirming the feasibility of the study in terms of recruitment uptake, retention, questionnaire completion, intervention fidelity, missing data, Fitbit wear adherence, and control group design. The intervention acceptability assessment showed high ratings, with eight out of ten items receiving >80% high ratings. At post-intervention, an analysis of covariance models showed a clinically significant increase in self-reported physical activity levels, psychological need satisfaction, and exercise motivation in the intervention group compared to controls. Lymfit also led to meaningful changes in six quality-of-life domains in the intervention group, including anxiety, depression, fatigue, sleep disturbance, social roles and activities, and pain interference. The findings support Lymfit as a promising means to meet psychological needs and increase the autonomous motivation for physical activity in this group. A fully powered efficacy trial is warranted to assess the validity of these findings.

The motivational effects of social contagion on exercise participation in young female adults.

Young inactive healthy-weight females (n = 42) were randomly assigned to exercise at a self-selected pace on a treadmill beside a confederate who was providing either intrinsic or externally regulated verbal primes. Heart rate (HR), rating of perceived exertion (RPE), percentage of time spent in moderate-to-vigorous physical activity (MVPA), and exercise continuance were recorded. Participants completed a self-report questionnaire assessing mood pre- and postexercise session and postexercise motivational outcomes. The intrinsic motivation group reported higher RPE values after 8 min of exercise, had higher recorded HR measures at all 5 recorded time points, exercised at a higher %HR max, spent more time in MVPA, and were more likely to continue to exercise than participants in the externally regulated motivation group. A time effect was noted for vigor. Based on these findings, exercise motivation can be "contagious" through verbal primes, suggesting that exercising with or around intrinsically motivated individuals may have beneficial outcomes.

Maximal heart rate prediction in adults that are overweight or obese.

An accurate predictor of maximal heart rate (MHR) is necessary to prescribe safe and effective exercise in those considered overweight and obese when actual measurement of MHR is unavailable or contraindicated. To date, accuracy of MHR prediction equations in individuals that are overweight or obese has not been well established. The purpose of this study was to examine the accuracy of 3 equations for predicting MHR in adults that are overweight or obese. One hundred seventy-three sedentary adults that were overweight or obese enrolled in weight-loss study and performed a VO2peak treadmill test before the start of the weight loss treatment. A total of 132 of the 173 participants met conditions for achieving maximal exercise testing criteria and were included in this study. Maximal heart rate values determined from VO2peak treadmill tests were compared across gender, age, and weight status with the following prediction equations: (a) 220 - age, (b) 208 - 0.7 × age, and (c) 200 - 0.48 × age. Among 20- to 40-year-old participants, actual MHR averaged 180 ± 9 b·min⁻¹ and was overestimated (p < 0.001) at 186 ± 5 b·min⁻¹ with the 220 - age equation. Weight status did not affect predictive accuracy of any of the 3 equations. For all participants, the equation, 200-0.48 × age estimated MHR to be 178 ± 4 b·min⁻¹, which was greater than the actual value (175 ± 12, p = 0.005). Prediction equations showed close agreement to actual MHR, with 208 - 0.7 × age being the most accurate.

Predicting exercise capacity through submaximal fitness tests in persons with multiple sclerosis.

OBJECTIVE: To estimate, for persons with multiple sclerosis (MS), the extent to which peak oxygen consumption (Vo(2)peak) can be predicted by the results on submaximal tests. DESIGN: Cross-sectional study. SETTING: Three MS clinics in the Greater Montreal region, Canada. PARTICIPANTS: A center-stratified random sample of 135 women and 48 men was drawn (N=183). A subgroup of 59 subjects with MS, who were able to perform the step test, was selected from this sample to complete the maximal exercise test. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURE: Vo(2)peak. RESULTS: In this sample (mean age +/- SD, 39 +/- 9 y; median Expanded Disability Status Scale=1.5), the mean Vo(2)peak +/- SD was 27.6 +/- 7.3 mL.kg(-1).min(-1). This value is considerably low when compared with healthy persons, ranking below the 25th percentile for both men and women. In a multivariate regression analysis, the step test and grip strength were identified as the only significant predictors of Vo(2)peak. When combined with body weight, grip strength and the step test explained 74% of the variance in Vo(2)peak. CONCLUSIONS: Patients with MS with a mild degree of disability exhibit marked reductions in exercise capacity. Also, in persons with MS, submaximal tests are good predictors of exercise capacity. These measures may be used in clinical settings to help assess and monitor maximum oxygen consumption and in research to evaluate the effect of exercise-related interventions. Furthermore, they will allow people with MS to self-monitor their exercise capacity and be more actively engaged in taking charge of their fitness level.

Sleep Duration and Timing in the Medium- to Long-Term Post-Bariatric Surgery.

Sleep duration improves short-term following bariatric surgery; however, little is known about its association with bodyweight medium- to long-term post-surgery. The purpose of this study was to describe sleep duration and its relationship with BMI and body composition. Forty-nine individuals, with a BMI of 36.6 ± 9.8 kg/m2, regained 26.4 ± 17.8% of their lost weight 9.5 ± 3.3 years post-surgery (range 3-16 years). Sleep logs and ActivPAL3 accelerometers were used to assess sleep duration. Participants averaged 7.9 ± 1.6 h/day and 8.5 ± 1.7 h/day of sleep for weekdays and weekends, respectively (P < 0.01). A positive association between delta weekend-weekday sleep timing midpoint with BMI (ß = 0.03, 95% CI = 0.01, 0.06; P = 0.01) was noted in the multivariable-adjusted model. On average, this sample achieved recommended sleep durations medium- to long-term post-surgery. Having an earlier sleep timing midpoint during the weekend may be associated with lower BMI.

Association of body fat with C-reactive protein in rheumatoid arthritis.

OBJECTIVE: The serum C-reactive protein (CRP) concentration is commonly used in rheumatoid arthritis (RA) as a surrogate marker of systemic inflammation, presumably induced by synovitis. However, other tissues, such as adipose tissue, can induce CRP production. This study was undertaken to explore the associations between measures of adiposity and CRP levels in RA. METHODS: One hundred ninety-six men and women with RA underwent anthropometric assessment and total body dual-energy x-ray absorptiometry for measurement of total and regional body fat and lean mass. The associations between measures of fat and lean mass and serum levels of CRP and interleukin-6 (IL-6) were determined in analyses stratified by sex, with adjustment for pertinent demographic, lifestyle, and RA disease and treatment covariates as well as for the potential modifying effects of articular activity and biologic pharmacotherapeutic agents. RESULTS: All measures of adiposity were significantly associated with the level of CRP in women, but not in men. In women, the measure of adiposity that showed the strongest association with the CRP level was truncal fat, in which, in adjusted analyses, each kilogram increase was associated with a 0.101-unit increase in the logarithmically transformed CRP level (P < 0.001). Neither the level of articular activity nor the use of biologic agents significantly modified this association in women. However, in men, elevated articular involvement was associated with a decreasing CRP level as truncal fat increased. For all analyses, substitution of IL-6 for CRP produced similar findings. CONCLUSION: Adiposity is independently associated with CRP levels in women with RA, and thus may confound the estimation of RA disease activity when serum CRP concentration is used as a surrogate for systemic inflammation.

Non-response bias in physical activity trend estimates.

BACKGROUND: Increases in reported leisure time physical activity (PA) and obesity have been observed in several countries. One hypothesis for these apparently contradictory trends is differential bias in estimates over time. The purpose of this short report is to examine the potential impact of changes in response rates over time on the prevalence of adequate PA in Canadian adults. METHODS: Participants were recruited in representative national telephone surveys of PA from 1995-2007. Differences in PA prevalence estimates between participants and those hard to reach were assessed using Student's t tests adjusted for multiple comparisons. RESULTS: The number of telephone calls required to reach and speak with someone in the household increased over time, as did the percentage of selected participants who initially refused during the first interview attempt. A higher prevalence of adequate PA was observed with 5-9 attempts to reach anyone in the household in 1999-2002, but this was not significant after adjustment for multiple comparisons. CONCLUSION: No significant impact on PA trend estimates was observed due to differential non response rates. It is important for health policy makers to understand potential biases and how these may affect secular trends in all aspects of the energy balance equation.