BackgroundA very limited amount of research has examined intermittent fasting (IF) programs, such as time-restricted feeding (TRF), in active populations.ObjectiveOur objective was to examine the effects of TRF, with or without β-hydroxy β-methylbutyrate (HMB) supplementation, during resistance training (RT).MethodsThis study employed a randomized, placebo-controlled, reduced factorial design and was double-blind with respect to supplementation in TRF groups. Resistance-trained females were randomly assigned to a control diet (CD), TRF, or TRF plus 3 g/d HMB (TRFHMB). TRF groups consumed all calories between 1200 h and 2000 h, whereas the CD group ate regularly from breakfast until the end of the day. All groups completed 8 wk of supervised RT and consumed supplemental whey protein. Body composition, muscular performance, dietary intake, physical activity, and physiological variables were assessed. Data were analyzed prior to unblinding using mixed models and both intention-to-treat (ITT) and per protocol (PP) frameworks.ResultsForty participants were included in ITT, and 24 were included in PP. Energy and protein intake (1.6 g/kg/d) did not differ between groups despite different feeding durations (TRF and TRFHMB: ∼7.5 h/d; CD: ∼13 h/d). Comparable fat-free mass (FFM) accretion (+2% to 3% relative to baseline) and skeletal muscle hypertrophy occurred in all groups. Differential effects on fat mass (CD: +2%; TRF: −2% to −4%; TRFHMB: −4% to −7%) were statistically significant in the PP analysis, but not ITT. Muscular performance improved without differences between groups. No changes in physiological variables occurred in any group, and minimal side effects were reported.ConclusionsIF, in the form of TRF, did not attenuate RT adaptations in resistance-trained females. Similar FFM accretion, skeletal muscle hypertrophy, and muscular performance improvements can be achieved with dramatically different feeding programs that contain similar energy and protein content during RT. Supplemental HMB during fasting periods of TRF did not definitively improve outcomes. This study was prospectively registered at clinicaltrials.gov as NCT03404271.

Objective: The purpose of the present study was to use a meta-analytic approach to examine the convergent validity of the International Physical Activity Questionnaire (IPAQ). Design: Systematic review by meta-analysis. Setting: The relevant studies were surveyed from five electronic databases. Primary outcomes of interest were the product-moment correlation coefficients between IPAQ and other instruments. Five separate meta-analyses were performed for each physical activity (PA) category of IPAQ: walking, moderate PA (MPA), total moderate PA (TMPA), vigorous PA (VPA) and total PA (TPA). The corrected mean effect size (ESr) unaffected by statistical artefacts (i.e. sampling error and reliability) was calculated for each PA category. Selected moderator variables were length of IPAQ (i.e. short and long form), reference period (i.e. last 7 d and usual week), mode of administration (i.e. interviewer and self-reported), language (i.e. English and translated) and instruments (i.e. accelerometer, pedometer and subjective measure). Subjects: A total of 152 ESr across five PA categories were retrieved from twentyone studies. Results:The results showed small-to medium-sized ESr (0?27-0?49). The highest value was observed in VPA while the lowest value was found in MPA. The ESr were differentiated by some of the moderator variables across PA categories. Conclusions: The study shows the overall convergent validity of IPAQ within each PA category. Some differences in degree of convergent validity across PA categories and moderator variables imply that different research conditions should be taken into account prior to deciding on use of the appropriate type of IPAQ. Keywords IPAQ Convergent validityMeta-analysis Physical activity Physical activity (PA) has been regarded as one of the most important habitual behaviours which leads to a healthy life by preventing diseases and increasing health benefits (1)(2)(3)(4)(5) . As the importance of PA has been emphasized, attempts have been made to develop appropriate measurement tools, including objective and subjective measurement tools, to quantify the amount of PA in daily life. Of these, questionnaires remain the most widely used measurement tool in large-scale studies due to their efficiency of measuring PA levels in large populations (6) .The International Physical Activity Questionnaire (IPAQ) is an instrument which was developed by the International Consensus Group in 1998-1999 to establish a standardized and culturally adaptable measurement tool across various populations in the world (7) . IPAQ is designed to assess the levels of habitual PA for individuals ranging from young to middle-aged adults (i.e. 15-69 years old). In addition, there are different forms of IPAQ depending on several variations which include length of questionnaire (i.e. short or long form), reference period (i.e. last 7 d or usual week) and mode of administration (i.e. self-report or interviewer-based).Soon after IPAQ was developed it was translated into several different languages and numerous...

This study examined the effects of utilizing a wearable activity tracker in a credit-based physical activity instructional program (PAIP) for promoting physical activity (PA) in college students. Fourteen PAIP courses in a large public university were randomly assigned into intervention (k = 7; n = 101) and control (k = 7; n = 86) groups. All courses focused on a core curriculum that covers basic exercise and behavioral science contents through lectures and activity sessions. A Misfit Flash activity tracker was provided to students in the intervention group. Objective PA assessments occurred at baseline, mid-, and end-of-semester during a 15-week academic semester. The control group showed a significant reduction in moderate- and vigorous-intensity PA (MVPA) minutes from baseline to the end-of-semester (P <.05), whereas the intervention group showed no changes in MVPA minutes over time. However, the intervention group also showed increased sedentary time and decreased time spent in light-intensity PA during the intervention period. Taken together, the present study found null effects of utilizing the wearable activity tracker in promoting PA in college students suggesting that intervention of primary using the wearable activity tracker as a behavior change strategy may not be effective to increase in PA in this setting.

BackgroundAccelerometer-based activity monitors are widely used in research and surveillance applications for quantifying sedentary behavior (SB) and physical activity (PA). Considerable research has been done to refine methods for assessing PA, but relatively little attention has been given to operationalizing SB parameters (i.e., sedentary time and breaks) from accelerometer data - particularly in relation to health outcomes. This study investigated: (a) the accrued patterns of sedentary time and breaks; and (b) the associations of sedentary time and breaks in different bout durations with cardiovascular risk factors.MethodsAccelerometer data on 5,917 adults from the National Health Examination and Nutrition Survey (NHANES) 2003–2006 were used. Sedentary time and breaks at different bout durations (i.e., 1, 2–4, 5–9, 10–14, 15–19, 20–24, 25–29, and ≥30-min) were obtained using a threshold of <100 counts per minute. Sedentary time and breaks were regressed on cardiovascular risk factors (waist circumference, triglyceride, and high-density lipoprotein cholesterol) and body mass index across bout durations.ResultsThe results revealed that the majority of sedentary time occurred within relatively short bout durations (≈70% and ≈85% for <5-min and <10-min, respectively). The associations of sedentary time and breaks with health outcomes varied depending on how bout time was defined. Estimates of SB parameters based on bout durations of 5 min or shorter were associated with reduced cardiovascular risk factors while durations longer than 10-min were generally associated with increased risk factors.ConclusionsThe present study demonstrates that the duration of sedentary bouts should be further considered when operationalizing the SB parameters from accelerometer data. The threshold of 5 minutes to define a bout is defensible, but a 10 minute threshold would provide a more conservative estimate to clearly capture the prolonged nature of sedentary behavior. Additional research is needed to determine the relative sensitivity and specificity of these thresholds.

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