Inter-individual differences in weight change following exercise interventions: a systematic review and meta-analysis of randomized controlled trials.

Previous reports of substantial inter-individual differences in weight change following an exercise intervention are often based solely on the observed responses in the intervention group. Therefore, we aimed to quantify the magnitude of inter-individual differences in exercise-mediated weight change. We synthesized randomized controlled trials (RCTs) of structured, supervised exercise interventions. Fourteen electronic databases were searched for relevant studies published up to March 2017. Search terms focused on structured training, RCTs and body weight. We then sifted these results for those RCTs (n = 12, 1500 participants) that included relevant comparator group data. Standard deviations (SDs) of weight change were extracted, thereby allowing the SD for true inter-individual differences in weight loss to be calculated for each study. Using a random effects meta-analysis, the pooled SD (95% CI) for true individual responses was 0.8 (-0.9 to 1.4) kg. The 95% prediction interval (based on 2SDs) for true inter-individual responses was -2.8 to 3.6 kg. The probability (% chance) that the true individual response variability would be clinically meaningful (>2.5 kg) in a future study in similar settings was 23% ('unlikely'). Therefore, we conclude that evidence is limited for the notion that there are clinically important individual differences in exercise-mediated weight change.

Randomized feasibility trial of high-intensity interval training before elective abdominal aortic aneurysm repair.

BACKGROUND: This study assessed the feasibility of a preoperative high-intensity interval training (HIT) programme in patients awaiting elective abdominal aortic aneurysm repair. METHODS: In this feasibility trial, participants were allocated by minimization to preoperative HIT or usual care. Patients in the HIT group were offered three exercise sessions per week for 4 weeks, and weekly maintenance sessions if surgery was delayed. Feasibility and acceptability outcomes were: rates of screening, eligibility, recruitment, retention, outcome completion, adverse events and adherence to exercise. Data on exercise enjoyment (Physical Activity Enjoyment Scale, PACES), cardiorespiratory fitness (anaerobic threshold and peak oxygen uptake), quality of life, postoperative morbidity and mortality, duration of hospital stay and healthcare utilization were also collected. RESULTS: Twenty-seven patients were allocated to HIT and 26 to usual care (controls). Screening, eligibility, recruitment, retention and outcome completion rates were 100 per cent (556 of 556), 43·2 per cent (240 of 556), 22·1 per cent (53 of 240), 91 per cent (48 of 53) and 79-92 per cent respectively. The overall exercise session attendance rate was 75·8 per cent (276 of 364), and the mean(s.d.) PACES score after the programme was 98(19) ('enjoyable'); however, the intensity of exercise was generally lower than intended. The mean anaerobic threshold after exercise training (adjusted for baseline score and minimization variables) was 11·7 ml per kg per min in the exercise group and 11·4 ml per kg per min in controls (difference 0·3 (95 per cent c.i. -0·4 to 1·1) ml per kg per min). There were trivial-to-small differences in postoperative clinical and patient-reported outcomes between the exercise and control groups. CONCLUSION: Despite the intensity of exercise being generally lower than intended, the findings support the feasibility and acceptability of both preoperative HIT and the trial procedures. A definitive trial is warranted. Registration number: ISRCTN09433624 ( https://www.isrctn.com/).

Do first impressions count? Frailty judged by initial clinical impression predicts medium-term mortality in vascular surgical patients.

Recognising frailty during pre-operative assessment is important. Frail patients experience higher mortality rates and are less likely to return to baseline functional status following the physiological insult of surgery. We evaluated the association between an initial clinical impression of frailty and all-cause mortality in 392 patients attending our vascular pre-operative assessment clinic. Prevalence of frailty assessed by the initial clinical impression was 30.6% (95% CI 26.0-35.2%). There were 133 deaths in 392 patients over a median follow-up period of 4 years. Using Cox regression, adjusted for age, sex, revised cardiac risk index and surgery (yes/no), the hazard ratio for mortality for frail vs. not-frail was 2.14 (95% CI 1.51-3.05). The time to 20% mortality was 16 months in the frail group and 33 months in the not-frail group. The initial clinical impression is a useful screening tool to identify frail patients in pre-operative assessment.

Predicting future weight status from measurements made in early childhood: a novel longitudinal approach applied to Millennium Cohort Study data.

BACKGROUND/OBJECTIVE: There are reports that childhood obesity tracks into later life. Nevertheless, some tracking statistics such as correlations do not quantify individual agreement, whereas others such as diagnostic test statistics can be difficult to translate into practice. We aimed to employ a novel analytic approach, based on ordinal logistic regression, to predict weight status of 11-year-old children from measurements at age 5 years. SUBJECTS/METHODS: The UK 1990 growth references were used to generate clinical weight status categories of 12 076 children enrolled in the Millennium Cohort Study. Using ordinal regression, we derived the predicted probability (percent chances) of 11-year-old children becoming underweight, normal weight, overweight, obese and severely obese from their weight status category at age 5 years. RESULTS: The chances of becoming obese (including severely obese) at age 11 years were 5.7% (95% confidence interval: 5.2 to 6.2%) for a normal-weight 5-year-old child and 32.3% (29.8 to 34.8%) for an overweight 5-year-old child. An obese 5-year-old child had a 68.1% (63.8 to 72.5%) chance of remaining obese at 11 years. Severely obese 5-year-old children had a 50.3% (43.1 to 57.4%) chance of remaining severely obese. There were no substantial differences between sexes. Nondeprived obese 5-year-old boys had a lower probability of remaining obese than deprived obese boys: -21.8% (-40.4 to -3.2%). This association was not observed in obese 5-year-old girls, in whom the nondeprived group had a probability of remaining obese 7% higher (-15.2 to 29.2%). The sex difference in this interaction of deprivation and baseline weight status was therefore -28.8% (-59.3 to 1.6%). CONCLUSIONS: We have demonstrated that ordinal logistic regression can be an informative approach to predict the chances of a child changing to, or from, an unhealthy weight status. This approach is easy to interpret and could be applied to any longitudinal data set with an ordinal outcome.

Cross-sectional Association between Walking Pace and Sleep-disordered Breathing.

Sleep-disordered breathing is an important comorbidity for several diseases, including stroke. Initial screening tools comprise simple yes/no questions about known risk factors for sleep-disordered breathing, e.g., obesity, sex. But walking speed has not been investigated in this context. We examined the cross-sectional association between walking pace and sleep-disordered breathing in the population-level Multi-Ethnic Study of Atherosclerosis. A sample of 2912 men and 3213 women (46-87 years) reported perceived walking pace outside their homes. A walking pace<0.89 m/s was deemed "slow", with ≥ 0.89 m/s considered "average/brisk" according to validated thresholds. Sample prevalences were: sleep apnoea (3.5%), self-reported apnoeas (8.4%), loud snoring (20.5%), daytime tiredness (22.2%) and slow-walking pace (26.9%). The 95% CI risk differences (multivariable-adjusted) for slow vs. faster walking pace were; sleep apnoea (0.4-2.5%), self-reported apnoeas (0.1-3.8%), loud snoring (1.2-8.3%), and daytime tiredness (3.0-7.8%). Risk differences were similar between sexes. The multivariable-adjusted risk ratio indicated that slower walkers had 1.5 (95% CI: 1.0 to 2.1) times the risk of sleep apnoea vs. faster walkers. In conclusion, a slower walking speed was associated with a greater prevalence of sleep-disordered breathing, independently from other common screening factors. Therefore, a simple walking speed question may help consolidate screening for this disorder.

Effect of supervised aerobic exercise rehabilitation on physical fitness and quality-of-life in survivors of critical illness: an exploratory minimized controlled trial (PIX study).

BACKGROUND: Evidence is limited for the effectiveness of interventions for survivors of critical illness after hospital discharge. We explored the effect of an 8-week hospital-based exercise-training programme on physical fitness and quality-of-life. METHODS: In a parallel-group minimized controlled trial, patients were recruited before hospital discharge or in the intensive care follow-up clinic and enrolled 8-16 weeks after discharge. Each week, the intervention comprised two sessions of physiotherapist-led cycle ergometer exercise (30 min, moderate intensity) plus one equivalent unsupervised exercise session. The control group received usual care. The primary outcomes were the anaerobic threshold (in ml O2 kg(-1) min(-1)) and physical function and mental health (SF-36 questionnaire v.2), measured at Weeks 9 (primary time point) and 26. Outcome assessors were blinded to group assignment. RESULTS: Thirty patients were allocated to the control and 29 to the intervention. For the anaerobic threshold outcome at Week 9, data were available for 17 control vs 13 intervention participants. There was a small benefit (vs control) for the anaerobic threshold of 1.8 (95% confidence interval, 0.4-3.2) ml O2 kg(-1) min(-1). This advantage was not sustained at Week 26. There was evidence for a possible beneficial effect of the intervention on self-reported physical function at Week 9 (3.4; -1.4 to 8.2 units) and on mental health at Week 26 (4.4; -2.4 to 11.2 units). These potential benefits should be examined robustly in any subsequent definitive trial. CONCLUSIONS: The intervention appeared to accelerate the natural recovery process and seems feasible, but the fitness benefit was only short term. CLINICAL TRIAL REGISTRATION: Current Controlled Trials ISRCTN65176374 (http://www.controlled-trials.com/ISRCTN65176374).

Technology-based dietary assessment: development of the Synchronised Nutrition and Activity Program (SNAP).

BACKGROUND: Accurate, reliable and feasible methods of dietary intake and physical activity assessment are required to improve our understanding of the associations between energy balance-related behaviours and health. METHODS: The Synchronised Nutrition and Activity Program (SNAP) was developed to enhance recall in children by integrating new and established methods of dietary intake and physical activity recall. A list of commonly consumed foods (n = 40), drinks (n = 9) and physical activities (n = 29) was used in SNAP. All foods and drinks were analysed by count (i.e., the number of times a particular food was selected), as a proxy indicator of dietary behaviours. All reported physical activities were assigned an intensity code [in metabolic equivalents (METs)] to determine minutes of moderate-vigorous activity (MVPA; ≥3 METs). RESULTS: Most participants completed a whole day's recall (both dietary intake and physical activities) in less than 25 min. SNAP was compared against 24-h multiple pass questionnaire and accelerometry in 121 children (aged 7-15 years old). For dietary variables, the accuracy of SNAP(™) (mean difference) was within ±1 count for the majority of food groups. The proportion of the sample with a between-method agreement within ±1 count ranged from 0.40 to 0.99. For MVPA, there was no substantial fixed or proportional bias, with a mean difference between methods (SNAP) - accelerometry) of -9 min of MVPA. Qualitatively, participants have indicated that they find SNAP easy and fun to use. CONCLUSIONS: SNAP was developed to be a simple, quick and engaging method of assessing energy balance-related behaviours at a group or population level and succeeded because it can collect a whole day's recall (dietary intake and physical activities) in less than 25 min to a reasonable and acceptable degree of accuracy.

Prevalence and implications of a difference in systolic blood pressure between one arm and the other in vascular surgical patients.

Inter-arm differences in blood pressure may confound haemodynamic management in vascular surgery. We evaluated 898 patients in the vascular pre-assessment clinic to determine the prevalence of inter-arm differences in systolic and mean arterial pressure, quantify the consequent risk of clinical error in siting monitoring peri-operatively and evaluate systolic inter-arm difference as a predictor of all-cause mortality (median follow-up 49 months). The prevalence of a systolic inter-arm difference ≥ 15 mmHg was 26% (95% CI 23-29%). The prevalence of an inter-arm mean arterial pressure difference ≥ 10 mmHg was 26% (95% CI 23-29%) and 11% (95% CI 9-13%) for a difference ≥ 15 mmHg. Monitoring could be erroneously sited in an arm reading lower for systolic pressure once in every seven to nine patients. The hazard ratio for a systolic inter-arm difference ≥ 15 mmHg vs < 15 mmHg was 1.03 (95% CI 0.78-1.36, p = 0.84). Large inter-arm blood pressure differences are common in this population, with a high potential for monitoring errors. Systolic inter-arm difference was not associated with medium-term mortality. [Correction added on 17 October 2013, after first online publication: In the Summary the sentence beginning 'We evaluated 898 patients' was corrected from (median (IQR [range]) follow-up 49 months) to read (median follow up 49 months)].

The practicality and effectiveness of supplementary bright light for reducing jet-lag in elite female athletes.

Although bright light can alter circadian timing, the practicality and effectiveness of supplementary bright light for reducing jet-lag symptoms in world-class athletes is unclear. Therefore, we randomised 22 world class female footballers to a bright light intervention or control group before a flight from USA to Europe. Intra-aural temperature, grip strength, sleep and various jet-lag symptoms were measured serially. For 4 days, the intervention participants were exposed, in pairs within their rooms, to 2 500 lux of bright light at ≈50 cm for 45-60 min at a time-of-day predicted to accelerate circadian adjustment. On post-flight day 1, indoor light transiently increased intra-aural temperature by 0.38°C (95%CI: 0.16 to 0.60, P=0.001) and increased overall jet-lag rating by ≈1 unit. Light had negligible effects on functioning, diet, bowel and sleep symptoms, which varied substantially between- and within-subjects. In conclusion, supplementary indoor light administered within the schedule of world-class athletes was not substantially effective for reducing jet-lag symptoms after a flight from the USA-Europe. Ours is the first study of the practical effectiveness of supplementary bright light in world class athletes, although sample size was naturally small, compromises were required to implement the intervention and there appears to be large inter-individual variation in the perception of what constitutes jet-lag.

Effects of exercise intensity on flow mediated dilation in healthy humans.

Previous studies have demonstrated conflicting results on the effects of acute exercise on FMD. The aim of the study was to examine brachial artery FMD before and after 3 bouts of acute exercise performed at different intensities. 10 healthy males (mean±SD age: 22±1 years) completed 30 min of cycling at 50, 70 and 85% maximal heart rate (HRmax). Brachial artery FMD and the shear rate area-under-the-curve (cuff deflation to peak dilation; SRAUC) were assessed pre- and immediately post-exercise using high-resolution echo-Doppler. A generalized estimating equation (GEE) analysis was used to estimate the effect magnitudes of exercise intensity and time (pre/post) on FMD, whilst controlling for the influence of baseline diameter and SRAUC. Both baseline diameter and SRAUC were elevated by exercise. With covariate-control of these variables, the decrease in brachial artery FMD was negligible after exercise at 50% HRmax (6.3±2.6 vs. 5.9±2.5%; 95%CI for difference: - 0.59-1.34%) with larger decreases in FMD after exercise at 70% (6.1±1.8 vs. 4.7±1.9%; 95%CI for difference: 0.08-2.58%) and at 85% HRmax (6.6±1.6 vs. 3.6±2.2%; 95%CI: 0.41-5.42%). In conclusion, even after accounting for exercise-mediated changes in shear and baseline diameter, our data indicate that a negative relationship exists between exercise intensity and FMD.

Validity of the 6 min walk test in prediction of the anaerobic threshold before major non-cardiac surgery.

BACKGROUND: For perioperative risk stratification, a robust, practical test could be used where cardiopulmonary exercise testing (CPET) is unavailable. The aim of this study was to assess the utility of the 6 min walk test (6MWT) distance to discriminate between low and high anaerobic threshold (AT) in patients awaiting major non-cardiac surgery. METHODS: In 110 participants, we obtained oxygen consumption at the AT from CPET and recorded the distance walked (in m) during a 6MWT. Receiver operating characteristic (ROC) curve analysis was used to derive two different cut-points for 6MWT distance in predicting an AT of <11 ml O(2) kg(-1) min(-1); one using the highest sum of sensitivity and specificity (conventional method) and the other adopting a 2:1 weighting in favour of sensitivity. In addition, using a novel linear regression-based technique, we obtained lower and upper cut-points for 6MWT distance that are predictive of an AT that is likely to be (P≥0.75) <11 or >11 ml O(2) kg(-1) min(-1). RESULTS: The ROC curve analysis revealed an area under the curve of 0.85 (95% confidence interval, 0.77-0.91). The optimum cut-points were <440 m (conventional method) and <502 m (sensitivity-weighted approach). The regression-based lower and upper 6MWT distance cut-points were <427 and >563 m, respectively. CONCLUSIONS: Patients walking >563 m in the 6MWT do not routinely require CPET; those walking <427 m should be referred for further evaluation. In situations of 'clinical uncertainty' (≥427 but ≤563 m), the number of clinical risk factors and magnitude of surgery should be incorporated into the decision-making process. The 6MWT is a useful clinical tool to screen and risk stratify patients in departments where CPET is unavailable.

Determination of the anaerobic threshold in the pre-operative assessment clinic: inter-observer measurement error.

The variability between observers in the interpretation of cardiopulmonary exercise tests may impact upon clinical decision making and affect the risk stratification and peri-operative management of a patient. The purpose of this study was to quantify the inter-reader variability in the determination of the anaerobic threshold (V-slope method). A series of 21 cardiopulmonary exercise tests from patients attending a surgical pre-operative assessment clinic were read independently by nine experienced clinicians regularly involved in clinical decision making. The grand mean for the anaerobic threshold was 10.5 ml O(2).kg body mass(-1).min(-1). The technical error of measurement was 8.1% (circa 0.9 ml.kg(-1).min(-1); 90% confidence interval, 7.4-8.9%). The mean absolute difference between readers was 4.5% with a typical random error of 6.5% (6.0-7.2%). We conclude that the inter-observer variability for experienced clinicians determining the anaerobic threshold from cardiopulmonary exercise tests is acceptable.

Effect of short-term exercise training on aerobic fitness in patients with abdominal aortic aneurysms: a pilot study.

BACKGROUND: Patients with abdominal aortic aneurysms (AAA) represent a high-risk surgical group. Despite medical optimization and radiological stenting interventions, mortality remains high and it is difficult to improve fitness. The aim of this pilot study was to evaluate the effect of a 6 week, supervised exercise programme (30 min continuous moderate intensity cycle ergometry, twice weekly) on anaerobic threshold (AT) in subjects with AAA. METHODS: Thirty participants with an AAA under surveillance were randomized to either the supervised exercise intervention (n=20) or a usual care control group (n=10). AT was measured using cardiopulmonary exercise testing, at baseline (AT1), week 5 (AT2), and week 7 (AT3). The change in AT (AT3-AT1) between the groups was compared using a mixed model ancova, providing the mean effect together with the standard deviation (sd) for individual patient responses to the intervention. The minimum clinically important difference (MCID) was defined as an improvement in AT of 2 ml O(2) kg(-1) min(-1). RESULTS: Of the 30 participants recruited, 17 of 20 (exercise) and eight of 10 (control) completed the study. The AT in the intervention group increased by 10% (equivalent to 1.1 ml O(2) kg(-1) min(-1)) compared with the control (90% confidence interval 4-16%; P=0.007). The sd for the individual patient responses to the intervention was 8%. The estimated number needed to treat (NNT) for benefit was 5 patients. CONCLUSIONS: The small mean benefit was lower than the MCID. However, the marked variability in the individual patient responses revealed that a proportion of patients did benefit clinically, with an estimated NNT of 5.

Reliability of the anaerobic threshold in cardiopulmonary exercise testing of patients with abdominal aortic aneurysms.

Anaerobic threshold (AT), determined by cardiopulmonary exercise testing (CPET), is a well-documented measure of pre-operative fitness, although its reliability in patient populations is uncertain. Our aim was to assess the reliability of AT measurement in patients with abdominal aortic aneurysms. Eighteen patients were recruited. CPET was performed four times over a 6-week period. We examined shifts in the mean AT to evaluate systematic bias with random measurement error assessed using typical within-patient error and intraclass correlation coefficient (ICC, 3,1) statistics. There was no significant or clinically substantial change in mean AT across the tests (p = 0.68). The typical within-patient error expressed as a percentage coefficient of variation was 10% (95% CI, 8-13%), with an ICC of 0.74 (95% CI, 0.55-0.89). We consider the reliability of the AT to be acceptable, supporting its clinical validity and utility as an objective marker of pre-operative fitness in this population.

The effect of a 9-week physical activity programme on bone and body composition of children aged 10-11 years: an exploratory trial.

A high-impact exercise and a lifestyle intervention were implemented over a 9-week period; changes in bone and body composition were compared to controls. Sixty-one children volunteered from three randomly selected schools. Each school was randomly assigned to either a structured exercise (STEX) intervention, a lifestyle intervention (PASS) or control (CONT). Bone mineral content (BMC) and density (BMD) of total body, femoral neck and lumbar spine were measured as well as fat and lean mass at baseline and post-intervention by dual-energy X-ray absorptiometry. The STEX intervention resulted in an additional mean increase in total body BMC of 63.3 g (p = 0.019) and an additional increase of 0.011 g . cm (-2) (p = 0.018) for BMD over increases observed by controls. Bone mineral increases observed for the PASS intervention were not significant compared to the control group (p > 0.05). Neither intervention produced significant increases in bone mineral at femoral neck or lumbar spine sites (p > 0.05) compared with the controls. No significant changes were found in fat mass index (p > 0.05), lean mass index (p > 0.05) or percent body fat (p = 0.09) in any groups. Structured impact exercise promoted significant and clinically relevant increases in bone measures, without significant changes to body composition. A larger, definitive randomised trial is needed to confirm the present results.

Characterising the individual performance responses to mild illness in international swimmers.

OBJECTIVES: To determine individual differences in the impact of illness on the change in performance of swimmers in international competitions. METHODS: Subjects were members of the Australian swimming team (33 male and 39 female, aged 15-27 years). Swimmers provided a weekly seven day recall of symptoms of illness during final six weeks of preparations for international competition over a three year period. Swimmers were categorised as either ill (one or more episodes of illness) or healthy. The measure of performances was the international point score. Mean changes in points score were calculated for healthy and ill swimmers between a national championship and an international competition ( approximately 16 weeks later). Likelihoods of substantial effects of illness on an individual's true change in performance (beneficial/trivial/harmful) were estimated from means and standard deviations, assuming a smallest substantial change of 6 points. RESULTS: Illness was reported before international performances by 38% of female and 35% of male swimmers. For female swimmers the change in performance was -3.7 (21.5) points (mean (SD)) with illness and -2.6 (19.0) points when healthy; for male swimmers the changes were -1.4 (17.5) points with illness and 5.6 (13.2) points when healthy. The likelihoods that illness had a substantial beneficial/trivial/harmful effect on performance of an individual swimmer were 32%/31%/37% for female and 17%/31%/52% for male participants (90% confidence limits approximately +/-10% to 20%). CONCLUSIONS: Although mild illness had only a trivial mean effect on female swimmers and a small harmful mean effect on male swimmers, there were substantial chances of benefit and harm for individuals.