The evolving definition of "sedentary".
ABSTRACT Studies that did not directly measure sedentary behavior often have been used to draw conclusions about the health effects of sedentariness. Future claims about the effects of sedentary, light, and moderate-to-vigorous activities on health outcomes should be supported by data from studies in which all levels of physical activity are differentiated clearly and measured independently.
SourceAvailable from: Reiner Hanewinkel[Show abstract] [Hide abstract]
ABSTRACT: The presented systematic review aims at giving a comprehensive overview of studies assessing the relationship between sedentary behavior and indicators of mental health in school-aged children and adolescents. Six online databases (MEDLINE, EMBASE, PsycINFO, PsycARTICLES, CINAHL and SPORTDiscus) as well as personal libraries and reference lists of existing literature were searched for eligible studies. Ninety-one studies met all inclusion criteria. There was strong evidence that high levels of screen time were associated with more hyperactivity/inattention problems and internalizing problems as well as with less psychological well-being and perceived quality of life. Concerning depressive symptoms, self-esteem, eating disorder symptoms, and anxiety symptoms, no clear conclusion could be drawn. But, taking quality assessment into account, self-esteem was negatively associated with sedentary behavior, i.e. high levels of time engaging in screen-based sedentary behavior were linked to lower scores in self-esteem. Overall, the association between sedentary behavior and mental health indicators was rather indeterminate. Future studies of high quality and with an objective measure of sedentary behavior will be necessary to further examine this association as well as to investigate longitudinal relationships and the direction of causality. Furthermore, more studies are needed to identify moderating and mediating variables. Copyright © 2015. Published by Elsevier Inc.Preventive Medicine 04/2015; DOI:10.1016/j.ypmed.2015.03.026 · 2.93 Impact Factor
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ABSTRACT: Available evidence suggests that young adults and seniors use different strategies to adjust for increasing body sway during quiet standing. Altered antagonist muscle co-activation and different ankle muscle coordination patterns may account for this finding. Consequently, we aimed at addressing whether aging leads to changes in neuromuscular coordination patterns as well as co-activation during quiet stance. We additionally investigated whether a bout of high intensity interval training additionally alters these patterns. Twenty healthy seniors (age: 70 ± 4 y) and twenty young adults (age: 27 ± 3 y) were enrolled in the present study. In between the testing procedures, four consecutive high-intensity intervals of 4 min duration at a target exercise intensity of 90 to 95% HRmax were completed on a treadmill. The total center of pressure (COP) path length displacement served as standing balance performance outcome. In order to assess ankle-muscle coordination patterns, amplitude ratios (AR) were calculated for each muscle (e.g. tibialis anterior (TA) [%] = (TA × 100) / (gastrocnemius medialis (GM) + soleus (SOL) + peroneus longus (PL) + TA) in order to assess the inter-muscular coordination of the ankle-muscles. The co-activation was calculated for the SOL and TA muscles computing the co-activation index (CAI = 2 × TA / TA + SOL). Seniors showed an inverted ankle muscle coordination pattern during single limb stance with eyes open (SLEO), compared to young adults (rest: GM, S: 15 ± 8% vs Y: 24 ± 9%; p = 0.03; SOL, S: 27 ± 14% vs Y: 37 ± 18%; p = 0.009; TA, S: 31 ± 13% vs Y: 13 ± 7%; p = 0.003). These patterns did not change after a high-intensity training sessions. A moderate correlation between amplitude ratios of TA-contribution and postural sway was observed for seniors during SLEO (r = 0.61). Ankle co-activation was twofold elevated in seniors compared to young adults during SLEO (p < 0.001). These findings were also not affected by high intensity training. Increased ankle co-activation in the anterior-posterior plane and inverted ankle muscle coordination pattern merely occurred during single-leg stance. Seniors with decreased postural control showed higher TA contributions during SLEO. These neuromuscular changes are not affected by acute exhaustive exercise.BMC Geriatrics 03/2015; 15(1):19. DOI:10.1186/s12877-015-0017-0 · 2.00 Impact Factor
Wonye kwahak kisulchi = Korean journal of horticultural science and technology / 02/2015; 33(1):133-142. DOI:10.7235/hort.2015.14084 · 0.34 Impact Factor