Tobias Engeroff

Health Benefits of Light-Intensity Physical Activity: A Systematic Review of Accelerometer Data of the National Health and Nutrition Examination Survey (NHANES)

BackgroundThe health effects of light-intensity physical activity (PA) are not well known today.ObjectiveWe conducted a systematic review to assess the association of accelerometer-measured light-intensity PA with modifiable health outcomes in adults and older adults.MethodsA systematic literature search up to March 2016 was performed in the PubMed, EMBASE, Web of Science and Google Scholar electronic databases, without language limitations, for studies of modifiable health outcomes in adults and older adults in the National Health and Nutrition Examination Survey accelerometer dataset.ResultsOverall, 37 cross-sectional studies and three longitudinal studies were included in the analysis, with considerable variation observed between the studies with regard to their operationalization of light-intensity PA. Light-intensity PA was found to be beneficially associated with obesity, markers of lipid and glucose metabolism, and mortality. Few data were available on musculoskeletal outcomes and results were mixed.ConclusionsObservational evidence that light-intensity PA can confer health benefits is accumulating. Currently inactive or insufficiently active people should be encouraged to engage in PA of any intensity. If longitudinal and intervention studies corroborate our findings, the revision of PA recommendations to include light-intensity activities, at least for currently inactive populations, might be warranted.

Appraising the methodological quality of cadaveric studies: validation of the QUACS scale.

Although systematic reviews are conducted in the field of anatomical research, no instruments exist for the assessment of study quality. Thus, our objective was to develop a valid tool that reliably assesses the methodological quality of observational cadaveric studies. The QUACS scale (QUality Appraisal for Cadaveric Studies) was developed using an expert consensus process. It consists of a 13‐item checklist addressing the design, conduct and report of cadaveric dissection studies. To evaluate inter‐rater reliability, a blinded investigator obtained an initial pool of 120 observational cadaveric studies. Sixty‐eight of them were selected randomly according to sample size calculations. Three independent researchers rated each publication by means of the QUACS scale. The reliability of the total score was estimated using the intraclass correlation coefficient (ICC). To assess agreement among individual items, margin‐free kappa values were calculated. For construct validity, two experts (an anatomist and an experienced physician) categorized the quality of 15 randomly selected studies as ‘excellent’ (4 points), ‘moderate to good’ (3 points), poor to moderate’ (2 points) or ‘poor’ (1 point). Kendalls tau rank correlation was used to compare the expert ratings with the scores on the QUACS scale. An evaluation of feasibility was carried out during the reliability analysis. All three raters recorded the duration of quality appraisal for each article. Means were used to describe average time exposure. The ICC for the total score was 0.87 (95% confidence interval: 0.82–0.92; P < 0.0001). For individual items, margin‐free kappa values ranged between 0.56 and 0.96 with an agreement of 69–97% among the three raters. Kendalls tau B coefficient of the association between expert ratings and the results obtained with the QUACS scale was 0.69 (P < 0.01). Required rating time per article was 5.4 ± 1.6 min. The QUACS scale is highly reliable and exhibits strong construct validity. Thus, it can confidently be applied in assessing the methodological quality of observational dissection studies.

Effects of aerobic exercise on brain metabolism and grey matter volume in older adults: results of the randomised controlled SMART trial

There is mounting evidence that aerobic exercise has a positive effect on cognitive functions in older adults. To date, little is known about the neurometabolic and molecular mechanisms underlying this positive effect. The present study used magnetic resonance spectroscopy and quantitative MRI to systematically explore the effects of physical activity on human brain metabolism and grey matter (GM) volume in healthy aging. This is a randomised controlled assessor-blinded two-armed trial (n=53) to explore exercise-induced neuroprotective and metabolic effects on the brain in cognitively healthy older adults. Participants (age >65) were allocated to a 12-week individualised aerobic exercise programme intervention (n=29) or a 12-week waiting control group (n=24). The main outcomes were the change in cerebral metabolism and its association to brain-derived neurotrophic factor (BDNF) levels as well as changes in GM volume. We found that cerebral choline concentrations remained stable after 12 weeks of aerobic exercise in the intervention group, whereas they increased in the waiting control group. No effect of training was seen on cerebral N-acetyl-aspartate concentrations, nor on markers of neuronal energy reserve or BDNF levels. Further, we observed no change in cortical GM volume in response to aerobic exercise. The finding of stable choline concentrations in the intervention group over the 3 month period might indicate a neuroprotective effect of aerobic exercise. Choline might constitute a valid marker for an effect of aerobic exercise on cerebral metabolism in healthy aging.

Specific smartphone usage and cognitive performance affect gait characteristics during free-living and treadmill walking

BACKGROUND Mobile phone tasks like texting, typing, and dialling during walking are known to impact gait characteristics. Beyond that, the effects of performing smartphone-typical actions like researching and taking self-portraits (selfie) on gait have not been investigated yet. RESEARCH QUESTION We aimed to investigate the effects of smartphone usage on relevant gait characteristics and to reveal potential association of basic cognitive and walking plus smartphone dual-task abilities. METHODS Our cross-sectional, cross-over study on physically active, healthy participants was performed on two days, interrupted by a 24-h washout in between. Assessments were: 1) Cognitive testing battery consisting of the trail making test (TMT A and B) and the Stroop test 2) Treadmill walking under five smartphone usage conditions: no use (control condition), reading, dialling, internet searching and taking a selfie in randomized order. Kinematic and kinetic gait characteristics were assessed to estimate conditions influence. RESULTS In our sample of 36 adults (24.6 ± 1 years, 23 female, 13 male), ANCOVAs followed by post-hoc t-tests revealed that smartphone usage impaired all tested gait characteristics: gait speed (decrease, all conditions): F = 54.7, p < 0.001; cadence (increase, all): F = 38.3, p < 0.001; double stride length (decrease, all): F = 33.8, p < 0.001; foot external rotation (increase during dialling, researching, selfie): F = 16.7, p < 0.001; stride length variability (increase): F = 11.7, p < 0.001; step width variability (increase): F = 5.3, p < 0.001; step width (Friedmann test and Wilcoxon Bonferroni-Holm-corrected post-hoc analyses, increase): Z = -2.3 to -2.9; p < 0.05); plantar pressure proportion (increase during reading and researching) (Z = -2.9; p < 0.01). The ability to keep usual gait quality during smartphone usage was systematically associated with the TMT B time regarding cadence and double stride length for reading (r = -0.37), dialling (r = -0.35) and taking a selfie (r = -0.34). SIGNIFICANCE Smartphone usage substantially impacts walking characteristics in most situations. Changes of gait patterns indicate higher cognitive loads and lower awareness.

Lifespan leisure physical activity profile, brain plasticity and cognitive function in old age

ABSTRACT Objectives: Despite the evidence suggesting physical activity (PA) as a major factor for the prevention of age-related cognitive decline, only a few studies have systematically investigated the impact of leisure PA during the lifespan (LLPA). This study investigates the effects of LLPA on cognitive function (CF) and brain plasticity (BP) in old age. Method: Participants’ (n = 50, 72 ± 5 yrs, 27 females) LLPA energy expenditure and volume was assessed via a validated questionnaire investigating five epochs (14–80 yrs). Using current WHO PA recommendations as reference, participants were stratified into energy expenditure and volume groups. CF outcomes were attention, executive functions, working memory and memory. BP was assessed using magnetic resonance spectroscopy (MRSI) and brain derived neurotropic factor (BDNF). Results: Correlation analysis revealed associations of mean LLPA energy expenditure with attention (CF) and N-acetylaspartate to choline ratios (NAA/Cho) (MRSI). ANOVA revealed higher interference control performance (CF) and NAA/Cho in participants complying with current PA recommendations (2-3 h per week) compared to non-compliers. Further CF and BP outcomes including BDNF were not associated with LLPA. Conclusion: Lifelong adherence to minimum recommended PA seems to be associated with markers of cognitive function and neuronal integrity in old age.

Sitzender Lebensstil und Gesundheit

Die meisten Menschen verbringen in Freizeit und Beruf viel Zeit in sitzender oder angelehnter Korperhaltung. Beobachtungsstudien ermitteln eine Verbindung dieses »sedentaren Verhaltens« (engl.: sedentary behavior) mit kardiometabolischen Erkrankungen, einigen Krebsarten sowie einem erhohten Sterberisiko. Als mogliche Wirkmechanismen werden akute und langerfristige Veranderungen des Energiestoffwechsels diskutiert. Speziell die Funktion einiger Schlusselenzyme des Glukose- und Fettstoffwechsels konnte bei diesen pathophysiologischen Veranderungen eine zentrale Rolle spielen. Erste Untersuchungen zeigen, dass sowohl die Unterbrechung sedentaren Verhaltens durch korperliche Aktivitat als auch die Vermeidung langer Sitzphasen einen positiven Einfluss haben konnen.

Breaking up sedentary time, physical activity and lipoprotein metabolism

OBJECTIVES Some authors report delayed responses of lipid metabolism after prolonged and interrupted sitting. To date no experimental studies have shown acute physical activity (PA) related changes of lipoprotein metabolism during sedentary behavior (SB). The purpose of this study was to examine immediate effects of a single PA-bout vs. regular PA-breaks on lipoprotein metabolism during postprandial SB. DESIGN Eighteen female subjects (25.6years±2.6; 21.5kg/m2±2.0) participated in a balanced crossover experiment with three trials: (1) 30min PA prior to 4h sitting (PRE), (2) 5×6min PA within 4h sitting (BREAK) (3) 4h sitting (CTRL). PA was ergometer cycling at 70%VO2max. Participants consumed one standardized breakfast in each trial. METHODS Total cholesterol (tChol), high density lipoprotein (HDL), low density lipoprotein (LDL) and triacylglycerol (TAG) readings were taken in fasted state at the beginning (before), and immediately after each trial. Multiple 2×3-ANOVAs (trial-arm*time) and post hoc t-tests were used. RESULTS ANOVAs revealed trial*time-effects for tChol (p=0.043) and HDL (p=0.007) and a tendency for LDL (p=0.078). Before-to-after differences (Δ) of tChol during BREAK-trial (-0.89±5.49mg/dl) significantly differed to Δ during PRE-trial (+3.56±5.32mg/dl) (p=0.005) but not to ΔCTRL (+2.16±8.72). ΔHDL during BREAK-trial (-2.11±3.31mg/dl) significantly differed to ΔPRE (+0.83±4.26mg/dl) (p=0.007) and ΔCTRL (+0.06±4.15mg/dl) (p=0.028). Analysis of TAG revealed a time effect (p=0.007) and significant differences between TAG before and after trial within BREAK (79.22±38.69mg/dl to 94.78±44.86mg/dl) and CTRL (80.94±32.94mg/dl to 97.72±41.19mg/dl) but not in PRE (78.83±33.13mg/dl to 89.06±33.83mg/dl). CONCLUSIONS Breaking sedentary behavior with vigorous intensity PA seem to decelerate postprandial lipoprotein metabolism during sitting. In contrast, prior PA, might be a stimulus for lipid metabolization.

Glucose metabolism from mouth to muscle: a student experiment to teach glucose metabolism during exercise and rest

We developed an experiment to help students understand basic regulation of postabsorptive and postprandial glucose metabolism and the availability of energy sources for physical activity in the fed and fasted state. Within a practical session, teams of two or three students (1 subject and 1 or 2 investigators) performed one of three different trials: 1) inactive, in which subjects ingested a glucose solution (75 g in 300 ml of water) and rested in the seated position until the end of the trial; 2) prior activity, in which the subject performed 15 min of walking before glucose ingestion and a subsequent resting phase; and 3) postactivity, in which the subject ingested glucose solution, walked (15 min), and rested afterwards. Glucose levels were drawn before trials (fasting value), immediately after glucose ingestion (0 min), and 5, 10, 15, 20, 25, 30, 40, 50, and 60 min thereafter. Students analyzed glucose values and worked on 12 tasks. Students evaluated the usefulness of the experiment; 54.2% of students found the experiment useful to enable them to gain a further understanding of the learning objectives and to clarify items, and 44.1% indicated that the experiment was necessary to enable them to understand the learning objectives. For 6.8% the experiment was not necessary but helpful to check what they had learned, and 3.4% found that the experiment was not necessary. The present article shows the great value of experiments within practical courses to help students gain knowledge of energy metabolism. Using an active learning strategy, students outworked complex physiological tasks and improved beneficial communication and interaction between students with different skill sets and problem-solving strategies.

Author’s Reply to Lopez: Comment on “Health Benefits of Light-Intensity Physical Activity: A Systematic Review of Accelerometer Data of the National Health and Nutrition Examination Survey (NHANES)”

Thank you for the opportunity to respond to Dr. Lopez’s letter [1]. Dr. Lopez expresses his doubts whether light intensity physical activity (LIPA) might be relevant for health and argues that we misinterpret current scientific evidence on the potential health effect of LIPA. We would like to take the opportunity to emphasize some important points he seems to have overlooked or disregarded in our work [2]. We are aware of the fact that the investigation of potential health effects of LIPA is a new and emerging field, with methodological limitations and many unanswered questions. To systematically assess the current state of evidence, we included both longitudinal and cross-sectional data and applied a rigorous quality rating. Since the necessary evidence for causal links is currently missing, we repeatedly underlined in our paper that further studies in this field are necessary. We explicitly acknowledged the limitations inherent in cross-sectional studies and the sparseness of experimental data to date. We were consciously cautious in formulating our interpretation regarding our findings. We stated, for example, that a ‘‘nuanced [italics added] view is warranted and LIPA should not ... be regarded as a panacea’’. We agree with Dr. Lopez that adjustments for moderatevigorous physical activity (MVPA) are necessary for a sound statistical analysis. Therefore we examined whether studies adjusting for MVPA contradict those that did not, and found that this was not the case. Of the three longitudinal studies we identified, two did adjust for MVPA [3, 4] and the third one applied the isotemporal substitution model, which also accounts for the effects of different intensity ranges [5]. Also, Fishman et al. used sensitivity analysis to limit the probability of reverse causality, excluding participants with mobility limitations and chronic diseases, which did not alter their results [5]. The body of literature concerning the effects of LIPA is growing fast. Since the completion of our literature review, at least two further longitudinal studies using NHANES data have been published, besides the one quoted by Dr. Lopez [6]. One, with a mean follow-up of 6.75 years, adjusted not only for MVPA but also for muscle strengthening activities, and excluded participants who died in the first year of follow-up and who had coronary artery disease, congestive heart failure or stroke at baseline [7]. The other study, with a mean follow-up of 6.35 years, applied the isotemporal substitution model and sensitivity analyses [8]. Both studies found a beneficial association between LIPA and mortality. Dr. Lopez further argues that ‘any acute exercise signal needs to exceed a certain ‘‘threshold stimulus’’,’ which we fully agree with. The intriguing question is at what intensity this threshold is. We propose—based on data we identified—that ‘‘health benefits of LIPA might be driven more by high LIPA than low LIPA, or, in other words, that there may be a minimal intensity threshold below which activities provide no quantifiable health benefits.’’ Our findings and interpretation of the data are upheld by & Eszter Füzéki fuezeki@sport.uni-frankfurt.de

Effects of high-intensity functional circuit training on motor function and sport motivation in healthy, inactive adults: XXXX

A small share of the worlds population meets current physical activity guidelines, which recommend regular engagement in endurance, strength, and neuromotor exercise. As lack of time represents a major cause of inactivity, multidimensional training methods with short durations may provide a promising alternative to classical, volume‐oriented approaches focusing on one biomotor ability. This trial examined the effects of a high‐intensity functional circuit training (HIFCT) on motor performance and exercise motivation in untrained adults.