Effects of Aerobic Exercise Training on Stress Reactivity in Every-Day Life

The current thesis investigated the effects of a 20-week aerobic exercise training on physiological and emotional responses to real-life stress using a randomized, controlled trial and an inactive sample. To assess participants\u27 physiological and psychological responses during everyday life, ambulatory assessment was used. In summary, the present thesis provides empirical support that regular exercise can lead to improved emotional and physiological responses during real-life stress

Aktivierung, Konzentration, Entspannung : Interventionsmöglichkeiten zur Förderung fitnessrelevanter Kompetenzen im Studium

Der Karlsruher Interventionskatalog stellt Lehrenden eine fundierte Auswahl kognitiver und körperlicher Übungen bereit. Zielsetzung dieser Interventionen ist die positive Beeinflussung von Konzentration, Befindlichkeit und emotionaler Aktivierung in Lehr-Lernsituationen im Hochschulkontext. Die Effekte zehnminütiger Interventionen, die sich aus verschiedenen Übungen des Katalogs zusammensetzen, wurden innerhalb von Lehrveranstaltungen an 150 Studierenden des KIT untersucht

Affect and subsequent physical activity: An ambulatory assessment study examining the affect-activity association in a real-life context

Traditionally, cognitive, motivational, and volitional determinants have been used to explain and predict health behaviors such as physical activity. Recently, the role of affect in influencing and regulating health behaviors received more attention. Affects as internal cues may automatically activate unconscious processes of behavior regulation. The aim of our study was to examine the association between affect and physical activity in daily life. In addition, we studied the influence of the habit of being physically active on this relationship. An ambulatory assessment study in 89 persons (33.7% male, 25 to 65 years, M = 45.2, SD = 8.1) was conducted. Affect was assessed in the afternoon on 5 weekdays using smartphones. Physical activity was measured continuously objectively using accelerometers and subjectively using smartphones in the evening. Habit strength was assessed at the beginning of the diary period. The outcomes were objectively and subjectively measured moderate-to-vigorous physical activity (MVPA) performed after work. Multilevel regression models were used to analyze the association between affect and after work MVPA. In addition, the cross-level interaction of habit strength and affect on after work MVPA was tested. Positive affect was positively related to objectively measured and self-reported after work MVPA: the greater the positive affect the more time persons subsequently spent on MVPA. An inverse relationship was found for negative affect: the greater the negative affect the less time persons spent on MVPA. The cross-level interaction effect was significant only for objectively measured MVPA. A strong habit seems to strengthen both the positive influence of positive affect and the negative influence of negative affect. The results of this study confirm previous results and indicate that affect plays an important role for the regulation of physical activity behavior in daily life. The results for positive affect were consistent. However, in contrast to previous reports of no or an inverse association, negative affect decreased subsequent MVPA. These inconsistencies may be—in part—explained by the different measurements of affect in our and other studies. Therefore, further research is warranted to gain more insight into the association between affect and physical activity

Impact of weekdays versus weekend days on accelerometer measured physical behavior among children and adolescents: results from the MoMo study = Einfluss des Wochentages auf das mit Beschleunigungsmessern erfasste Bewegungsverhalten von Kindern und Jugendlichen: Ergebnisse der MoMo-Studie

Structured activities, in which children participate for example at school, are consistent and limited in scope. After-school or weekend activities, by contrast, involve a wider range of behaviors. Studies have shown that physical activity (PA), as measured by accelerometers, is lower on weekends compared to weekdays or school days, whereas PA does not differ between weekdays. In the present study, we examined accelerometer data of children and adolescents living in Germany for the different weekdays and weekend days. The current analysis used cross-sectional data of participants (n = 2743) aged 6–17 years collected between 2014 and 2017. The final valid sample consisted of 2278 children and adolescents divided into three age groups (6–10 years, n = 713; 11–13 years, n = 706; 14–17 years, n = 859) and two gender groups (1072 boys, 1206 girls). Physical behavior, including sedentary behavior, as well as light, moderate, vigorous PA, and wear time were analyzed. Absolute and percentage intensity distributions were evaluated daily. The average wear time was 807 min daily from Monday–Thursday with significant deviations from the mean on Friday (+38 min), Saturday (−76 min), and Sunday (−141 min). Absolute moderate to vigorous PA times were lower on weekends than during the week. However, the percentage intensity distribution remained constant over all days. Girls were less physically active and more sedentary than boys (F$_{1,2272}$ = 38.3; p < 0.01) and adolescents were significantly less active than younger children (F$_{2,2272}$ = 138.6; p < 0.01). Waking times increased with age (F$_{2,2272}$ = 138.6; p < 0.01). Shorter awake periods limit possible active times on weekends, resulting in lower PA and sedentary behavior compared to weekdays. The percentage distributions of the different physical behavior intensity categories are similar over all weekdays and weekend days. We could not find a justification for specific weekend interventions. Instead, interventions should generally try to shift activity away from sedentary behavior towards a more active lifestyle

How specific combinations of epoch length, non-wear time and cut-points influence physical activity – Processing accelerometer data from children and adolescents in the nationwide MoMo study = Einfluss spezifischer Kombinationen von Epochenlänge, Nichttragezeit und Cut-off-Werten auf die körperliche Aktivität – Signalverarbeitung von Akzelerometerdaten bei Kindern und Jugendlichen in der bundesweiten MoMo-Studie

This study assesses three factors that influence the quantification of children’s and adolescents’ physical activity (PA) using accelerometers: selection of (1) non-wear algorithm, (2) epoch length and (3) cut-points. A total of 1525 participants from MoMo wave 3 (2018–2022), aged 6–17 years, wore GT3X accelerometers (ActiGraph, LLC, Pensacola, FL, USA) during waking hours. Acceleration counts were reintegrated into lengths of 1, 5, 15, 30, and 60 s epochs. Two non-wear time algorithms and two sets of cut-points were applied to each epoch length. Differences were found in both the comparison of the non-wear time algorithms and the comparison of the cut-points when the different epoch lengths were considered. This may result in large differences in estimated sedentary behavior and PA values. We propose to pool the data by merging and combining multiple accelerometer datasets from different studies and evaluate them in a harmonized way in the future. In addition to the need for future validation studies using short epoch lengths for young children, we also propose to conduct meta-analyses. This allows the use of data from multiple studies to validate cut-points and to propose a consensual set of cut-points that can be used in different settings and projects. The high discrepancy between results when comparing different epoch lengths has to be considered when interpreting accelerometer data and is regarded a confounding variable when comparing levels of PA between studies

Characteristics of the activity-affect association in inactive people : an ambulatory assessment study in daily life

Acute and regular exercise as well as physical activity is related to wellbeing and positive affect. Recent studies have shown that even daily, unstructured physical activities increase positive affect. However, the attempt to achieve adherence to physical activity or exercise in inactive people through public health interventions has often been unsuccessful. Most studies analyzing the activity-affect association in daily life, did not report participants&#180; habitual activity behavior. Thus, samples included active and inactive people, but they did not necessarily exhibit the same affective reactions to physical activity in daily life. Therefore the present study investigated whether the association between physical activity and subsequent affective state in daily life can also be observed in inactive individuals. We conducted a pilot study with 29 inactive university students (mean age 21.3 yrs &#177; 1.7) using the method of ambulatory assessment. Affect was assessed via electronic diary and physical activity was measured with accelerometers. Participants had to rate affect every two hours on a six item bipolar scale reflecting the three basic mood dimensions energetic arousal, valence and calmness. We calculated activity intensity level (mean Metabolic Equivalent (MET) value) and the amount of time spent in light activity over the last 15 minutes before every diary prompt and conducted within-subject correlations. We did not find significant associations between activity intensity and the three mood dimensions. Due to the high variability in within-subject correlations we conclude that not all inactive people show the same affective reactions to physical activity in daily life. Analyzing the physical activity-affect association of inactive people was difficult due to little variance and distribution of the assessed variables. Interactive assessment and randomized controlled trials might help solving these problems. Future studies should examine characteristics of affec

Biodiversität und Landschaftsbild in der Ökobilanzierung von Biogasanlagen

Im Zuge der angestrebten Energiewende ist eine weitere Nutzung von Biomasse notwendig. Vor dem Hintergrund von zunehmenden Nutzungskonflikten muss sich die zukünftige Entwicklung jedoch an ökologischen Grenzen und vor allem auch am Zustand der Schutzgüter orientieren. Zur Bewertung zukünftiger und auch aktueller Entwicklungen wird häufig die Ökobilanzierung als Instrument zur umfassenden Umweltwirkungsabschätzung eingesetzt. Insbesondere im Hinblick auf die Bewertung von potenziellen Auswirkungen auf das Schutzgut Biodiversität weist die räumlich unspezifische Ökobilanz jedoch Wissens- und Methodendefizite auf. Denn gerade diese Wirkungskategorie kann nicht – wie es der Produktsicht von Ökobilanzen entspricht – raumunspezifisch betrachtet werden. Vor dem Hintergrund der zunehmenden Nutzung von Biomasse war es dementsprechend das übergeordnete Ziel des vorliegenden Forschungsvorhabens, einen Ansatz zur Integration von Auswirkungen des Energiepflanzenanbaus auf die Biodiversität in die Ökobilanz am Beispiel der Biogaserzeugung zu entwickeln. Angepasst an die niedersächsische Datensituation wurden Kriterien und Indikatoren für eine ökobilanzielle Bewertung von Nutzungseinflüssen und Wirkungen des Energiepflanzenanbaus auf die Biodiversität (Arten und Biotope) und das Landschaftsbild zusammengestellt. Die hierauf aufbauende Methode wurde auf zwei niedersächsischen Beispielbetrieben erprobt und in das Betriebsmanagementsystem MANUELA implementiert. Auf dieser Grundlage wurde ein Konzept für die Integration der Bewertungsmethode bzw. von vorgelagerten Bewertungsergebnissen aus MANUELA in die Ökobilanzierungssoftware Umberto erarbeitet. Die Bewertung der potenziellen Wirkungen des Energiepflanzenanbaus auf die Biodiversität baut auf bestehende Methoden auf und wurde weiterentwickelt. Schlagspezifische Daten zum Anbauverfahren wurden mit Daten der Ackerwildkrautvielfalt kombiniert und mit einer differenzierten Biotopwertskala verknüpft, um den Zustand der Biodiversität einer Fläche zu beschreiben. Dieses Bewertungsergebnis wurde als kardinal skalierter, aggregierter Biotopausprägungswert – hier als differenzierter Biotopwert bezeichnet – unter Berücksichtigung der Indikatoren Anbauweise und Fruchtart, Standort und Landschaftsheterogenität abgebildet. Dieser differenzierte Biotopwert ist schlagbezogen und unabhängig vom Anbauflächenbedarf für das zu produzierende Substrat zu betrachten. Im Rahmen der Methodenanwendung auf zwei konventionellen Ackerbaubetrieben wurden übergreifend betrachtet differenzierte Biotopwerte von 0,9 bis 2,2 ermittelt (auf einer Skala von insgesamt 0,1 bis 5,9). Die Bewertung auf Ebene des landwirtschaftlichen Betriebs erfolgte über das flächengewichtete Mittel des differenzierten Biotopwerts. Dieser lag für beide im Bereich 1,2 bis 1,3 und deutet damit auf einen aktuell geringen Wert für die Biodiversität mit deutlichem Aufwertungsspielraum hin. Im Rahmen einer Validierung wurde die einzelschlagbezogene modellierte Biodiversitätsbewertung durch vor Ort erfasste Daten der Ackerwildkrautvielfalt bestätigt. Aufbauend auf dieser biotopwertbasierten Methode für die Biodiversitätsbewertung wurde ein teilautomatisiertes Tool zur schlag- und betriebsbezogenen Bewertung in das Betriebsmanagementsystem MANUELA implementiert. Hierüber können auf der Grundlage einfach erhebbarer Indikatoren Einzelschlag- und Betriebsbewertungen durchgeführt werden, die als Grundlage für die Optimierung des Betriebsmanagements genutzt werden können. Mit dem Ziel einer Integration dieser standortabhängigen Biodiversitätsbewertung in die Ökobilanzierung wurden zwei Bewertungsansätze in Umberto umgesetzt und deren Wirkungsindikatoren in das Kennzahlensystem für die Wirkungsabschätzung implementiert: Der erste Ansatz stellt die Übernahme der o.g. biotopwertbasierten Methode dar, wobei der differenzierte Biotopwert als Informationsgröße im Stoffstrommodell der Biogasanlage mitgeführt wird. Die für die Berechnung dieser Informationsgröße notwendigen Indikatoren und das Vorgehen entsprechen der oben beschriebenen Methode. In einem zweiten erweiterten Ansatz erfolgte die Wirkungsabschätzung auf Basis der auf den Einzelschlägen erfassten Artenzahlen der Ackerwildkrautflora im Vergleich zu der auf einem definierten Standort potenziell maximal möglichen Artenzahl. Dafür erfolgte der Rückgriff auf schlagspezifische Bewirtschaftungsfaktoren und deren Zusammenhang mit der schlagspezifischen Artenvielfalt. Dadurch entsteht ein unmittelbarer Bezug zu den in der klassischen Ökobilanz genutzten Inputs und Outputs des untersuchten Systems. Als Wirkungsindikatorwert wurde die ‚Reduzierte Anzahl Ackerwildkräuter‘ definiert. Durch den Abgleich mit der potenziell maximal möglichen Zahl der Ackerwildkrautarten auf einem Standort lässt sich im Ergebnis das noch ausschöpfbare Biodiversitätspotenzial eines Schlages und damit dessen Aufwertungspotenzial beschreiben. Dieses kann als Grundlage für Optimierungen im Betriebsmanagement herangezogen werden, indem ein schlagbezogener Vergleich der Wirkungskategorie Biodiversität mit den Ergebnissen anderer Wirkungskategorien (z.B. Klimawandel) auf Basis einer funktionellen Einheit (hier 1 t FM Silomais) erfolgt. Dies ermöglicht die Identifizierung ggf. möglicher Synergien oder auch gegenläufiger Wirkungen verschiedener Wirkungskategorien und kann so für die gezielte Flächenauswahl biodiversitätsfördernder Maßnahmen genutzt werden. Vergleichbar zu der Biodiversitätsbewertung (Ansatz 1) wurde eine Methode zur Bewertung der potenziellen Wirkungen des Energiepflanzenanbaus auf das Landschaftsbild entwickelt. Es erfolgte eine landschaftsästhetische Bewertung der Fruchtarten und Betriebe unter Berücksichtigung der Indikatoren Landschaftskomponente (inkl. deren spezifischer Ausprägung) und landschaftliche Vielfalt. Beide wurden zu einem landschaftsästhetischen Wert aggregiert, der als flächengewichtetes Mittel für die Bewertung des Betriebs genutzt wurde. Dieser lag für die betrachteten Beispielbetriebe im Bereich 2,3 bis 2,4 auf einer Skala von insgesamt 1 bis 10 und deutet somit auf eine geringe landschaftsästhetische Bedeutung des betrachteten Landschaftsraums hin. Analog zur Implementierung des differenzierten Biotopwerts in der Biodiversitätsbewertung (Ansatz 1) kann auch der landschaftsästhetische Wert als Informationsgröße im Stoffstrommodell mitgeführt werden. Eine Integration von Landschaftsbildaspekten in Anlehnung an den 2. Ansatz zur Biodiversitätsbewertung erscheint grundsätzlich machbar, ist aber aufgrund des erhöhten Datenbedarfs schwerer umzusetzen. Die entwickelten Methoden zur Biodiversitäts- und Landschaftsbildbewertung eignen sich somit zur Abbildung von Unterschieden der potenziellen Wirkungen des Energiepflanzenanbaus anhand einfach erhebbarer Indikatoren. Für die Anwendung der Methoden sind Daten erforderlich, die direkt bei Landwirten oder aber zumindest bei landwirtschaftlichen Beratern vorliegen. Beide Methoden sind sowohl auf der Ebene Schlag/Einzelkultur als auch auf der Ebene Betrieb/Fruchtfolge einsetzbar. Eine Kopplung dieser Methoden an die Ökobilanz wurde demonstriert. Die weitere Forschung dient der Präzisierung und Nachjustierung der erarbeiteten Bewertungsklassen und bedarf eines Ausbaus der Datenbasis, beispielsweise im Hinblick auf die Wirkung anderer Anbauweisen (z.B. Ökolandbau) oder Landschaftsräume.In order to implement a transition from non-renewable to renewable energy sources in Germany, a sustainable expansion of biomass use is necessary. Due to increasing land use conflicts, this expansion needs to be oriented towards environmental limits as well as towards the status of legally protected goods. The potential impacts of future and current developments regarding the renewable energy sector are often assessed using a life cycle assessment (LCA). However, the LCA is usually spatially unspecific and thus has considerable shortcomings concerning its methods, particularly with regard to an evaluation of the potential impacts on biodiversity. Additionally, there is a lack of knowledge concerning the quantitative relationship between agricultural activity and biodiversity. However, the spatial dimension must be considered for assessing impacts on biodiversity. Therefore, the objective of the present research was to develop an approach for the integration of the impacts of energy plant cropping on biodiversity into LCA using the example of biogas production. We developed criteria and indicators for a life cycle impact assessment which will estimate the effects of energy plant cropping on biodiversity (species and habitats) and visual landscape in Lower Saxony. The evaluation of potential effects of cultivating energy crops on species and field habitats is based on existing methods. These methods have been further developed in the course of the current project. Accordingly, the key indicators that provided sufficient information on the biodiversity status of a field habitat were (i) the farming practice (conventional or organic) and crop type, (ii) the site conditions as well as (iii) the landscape heterogeneity. This field specific data was combined with data on field flora species richness and was then merged with a habitat value scale to model a single aggregated habitat value. The modelled habitat value describes the biodiversity status of a field site in terms of a ratio scale. It is independent of the acreage required for the biogas substrate. For the farm level evaluation the area-weighted mean of the field-specific evaluation was used. The method was tested on two farms in Lower Saxony and was implemented into the farm management software MANUELA. We verified the field-specific modelled biodiversity through on-site surveys of the field flora species richness. Using the easily determined and robust indicators mentioned above, it is possible to optimise the on-farm operational management. Furthermore, the approach and its corresponding indicators were implemented into the indicator system of the LCA software Umberto in two different ways. Firstly, the above mentioned habitat value-based method was adopted. In this way the habitat value is defined as an informational factor, which is carried along the material flow model of the biogas plant. Secondly, an impact assessment based on the comparison of surveys of field flora species richness and the site-specific potential maximum species richness was conducted. For this purpose site-specific management factors were related to the surveyed site-specific species richness. As a result, a direct reference was derived between outputs of the system under examination and inputs which were used in the classical LCA of the biogas plants. As impact indicator score the ‘reduced amount of field flora species richness’ has been defined. By comparing the reduced amount with the maximum species richness, the upside biodiversity potential is described. This potential can serve as a basis for improvements of the farm-related operational management by comparing the field-related results of the impact category biodiversity with results of other impact categories (e.g. climate change) using a functional unit (here: 1 t fresh matter silage corn). This enables identification of possible synergies as well as trade-offs of different impact categories. Thus, an appropriately targeted area selection for farming methods that promote biodiversity is possible. In addition, an approach for integrating the impacts of energy plant cropping on the visual landscape into LCA was developed. The key indicators that provided sufficient information on the relation between agricultural practices and the visual landscape were (i) the occurrence of different landscape components like fields, meadows or groves including their specific characteristics, (ii) the diversity of crop types and (iii) the structural diversity of the landscape. As a further development all three indicators were combined to create a single aggregated value for each landscape component. For the farm level evaluation the area-weighted mean was used. The results of the visual landscape assessment can be defined as an informational factor which can be carried along the material flow model of the biogas plant. An incorporation of aspects of the visual landscape into the LCA of biogas plants according to the second approach of the biodiversity assessment is similarly difficult to put into practice because of enhanced data requirements and the viewers’ subjective perception. In summary, the presented methods for biodiversity and visual landscape assessment are suitable for illustrating different effects of energy plant cropping by means of rather simple indicators. The necessary data can be easily obtained from the farmers themselves or from agricultural advisers. Both methods are applicable at the field level (i.e. the level of single crop types) and at the farm level (i.e. at the level of the crop rotation). These methods can be linked with classical LCA. Further research needs to specify and readjust the applied evaluation rules and needs to include other data, e.g. with regard to other farming practices like organic farming

Acute and medium term effects of a 10-week running intervention on mood state in apprentices

Exercise and physical activity have proven benefits for physical and psychological well-being. However, it is not clear if healthy young adults can enhance mood in everyday life through regular exercise. Earlier studies mainly showed positive effects of acute exercise and exercise programs on psychological well-being in children, older people and in clinical populations. Few studies controlled participants' physical activity in daily life, performed besides the exercise program, which can impact results. In addition the transition from mood enhancement induced by acute exercise to medium or long-term effects due to regular exercise is not yet determined. The purpose of this pilot study was to examine the acute effects of an aerobic running training on mood and trends in medium term changes of mood in everyday life of young adults. We conducted a 10-week aerobic endurance training with frequent mood assessments and continuous activity monitoring. 23 apprentices, separated into experimental and control group, were monitored over 12 weeks. To control the effectiveness of the aerobic exercise program, participants completed a progressive treadmill test pre and post the intervention period. The three basic mood dimensions energetic arousal, valence and calmness were assessed via electronic diaries. Participants had to rate their mood state frequently on 3 days a week at five times of measurement within 12 weeks. Participants' physical activity was assessed with accelerometers. All mood dimensions increased immediately after acute endurance exercise but results were not significant. The highest acute mood change could be observed in valence (p = 0.07; η(2) = 0.27). However, no medium term effects in mood states could be observed after a few weeks of endurance training. Future studies should focus on the interaction between acute and medium term effects of exercise training on mood. The decreasing compliance over the course of the study requires the development of strategies to maintain compliance over longer periods

Quality Evaluation of Free-living Validation Studies for the Assessment of 24-Hour Physical Behavior in Adults via Wearables: Systematic Review.

BACKGROUND Wearable technology is a leading fitness trend in the growing commercial industry and an established method for collecting 24-hour physical behavior data in research studies. High-quality free-living validation studies are required to enable both researchers and consumers to make guided decisions on which study to rely on and which device to use. However, reviews focusing on the quality of free-living validation studies in adults are lacking. OBJECTIVE This study aimed to raise researchers' and consumers' attention to the quality of published validation protocols while aiming to identify and compare specific consistencies or inconsistencies between protocols. We aimed to provide a comprehensive and historical overview of which wearable devices have been validated for which purpose and whether they show promise for use in further studies. METHODS Peer-reviewed validation studies from electronic databases, as well as backward and forward citation searches (1970 to July 2021), with the following, required indicators were included: protocol must include real-life conditions, outcome must belong to one dimension of the 24-hour physical behavior construct (intensity, posture or activity type, and biological state), the protocol must include a criterion measure, and study results must be published in English-language journals. The risk of bias was evaluated using the Quality Assessment of Diagnostic Accuracy Studies-2 tool with 9 questions separated into 4 domains (patient selection or study design, index measure, criterion measure, and flow and time). RESULTS Of the 13,285 unique search results, 222 (1.67%) articles were included. Most studies (153/237, 64.6%) validated an intensity measure outcome such as energy expenditure. However, only 19.8% (47/237) validated biological state and 15.6% (37/237) validated posture or activity-type outcomes. Across all studies, 163 different wearables were identified. Of these, 58.9% (96/163) were validated only once. ActiGraph GT3X/GT3X+ (36/163, 22.1%), Fitbit Flex (20/163, 12.3%), and ActivPAL (12/163, 7.4%) were used most often in the included studies. The percentage of participants meeting the quality criteria ranged from 38.8% (92/237) to 92.4% (219/237). On the basis of our classification tree to evaluate the overall study quality, 4.6% (11/237) of studies were classified as low risk. Furthermore, 16% (38/237) of studies were classified as having some concerns, and 72.9% (173/237) of studies were classified as high risk. CONCLUSIONS Overall, free-living validation studies of wearables are characterized by low methodological quality, large variability in design, and focus on intensity. Future research should strongly aim at biological state and posture or activity outcomes and strive for standardized protocols embedded in a validation framework. Standardized protocols for free-living validation embedded in a framework are urgently needed to inform and guide stakeholders (eg, manufacturers, scientists, and consumers) in selecting wearables for self-tracking purposes, applying wearables in health studies, and fostering innovation to achieve improved validity

Quality Evaluation of Free-living Validation Studies for the Assessment of 24-Hour Physical Behavior in Adults via Wearables: Systematic Review

Background: Wearable technology is a leading fitness trend in the growing commercial industry and an established method for collecting 24-hour physical behavior data in research studies. High-quality free-living validation studies are required to enable both researchers and consumers to make guided decisions on which study to rely on and which device to use. However, reviews focusing on the quality of free-living validation studies in adults are lacking. Objective: This study aimed to raise researchers’ and consumers’ attention to the quality of published validation protocols while aiming to identify and compare specific consistencies or inconsistencies between protocols. We aimed to provide a comprehensive and historical overview of which wearable devices have been validated for which purpose and whether they show promise for use in further studies. Methods: Peer-reviewed validation studies from electronic databases, as well as backward and forward citation searches (1970 to July 2021), with the following, required indicators were included: protocol must include real-life conditions, outcome must belong to one dimension of the 24-hour physical behavior construct (intensity, posture or activity type, and biological state), the protocol must include a criterion measure, and study results must be published in English-language journals. The risk of bias was evaluated using the Quality Assessment of Diagnostic Accuracy Studies-2 tool with 9 questions separated into 4 domains (patient selection or study design, index measure, criterion measure, and flow and time). Results: Of the 13,285 unique search results, 222 (1.67%) articles were included. Most studies (153/237, 64.6%) validated an intensity measure outcome such as energy expenditure. However, only 19.8% (47/237) validated biological state and 15.6% (37/237) validated posture or activity-type outcomes. Across all studies, 163 different wearables were identified. Of these, 58.9% (96/163) were validated only once. ActiGraph GT3X/GT3X+ (36/163, 22.1%), Fitbit Flex (20/163, 12.3%), and ActivPAL (12/163, 7.4%) were used most often in the included studies. The percentage of participants meeting the quality criteria ranged from 38.8% (92/237) to 92.4% (219/237). On the basis of our classification tree to evaluate the overall study quality, 4.6% (11/237) of studies were classified as low risk. Furthermore, 16% (38/237) of studies were classified as having some concerns, and 72.9% (173/237) of studies were classified as high risk. Conclusions: Overall, free-living validation studies of wearables are characterized by low methodological quality, large variability in design, and focus on intensity. Future research should strongly aim at biological state and posture or activity outcomes and strive for standardized protocols embedded in a validation framework. Standardized protocols for free-living validation embedded in a framework are urgently needed to inform and guide stakeholders (eg, manufacturers, scientists, and consumers) in selecting wearables for self-tracking purposes, applying wearables in health studies, and fostering innovation to achieve improved validity