Cardiorespiratory fitness and muscular fitness correlates in youth: A hierarchy of behavioral, contextual, and health-related outcomes.

OBJECTIVES: Despite the health importance of identifying correlates of physical fitness in youth, no investigation to date has explored the influence of behavioral, health-related, and contextual correlates simultaneously. We investigated the hierarchical relationship of multiple modifiable correlates favoring or diminishing cardiorespiratory and muscular fitness in youth. DESIGN: Cross-sectional investigation. METHODS: In a sample of 5174 children and adolescents, 31 correlates were hierarchized according to their impact on cardiorespiratory and muscular fitness assessed using the FITESCOLA® fitness battery. A Chi-squared Automatic Interaction Detection approach was employed and measures of correlation and association were used to investigate the relationship between physical fitness and correlates. RESULTS: In children, body mass index was the most relevant factor to discriminate between high and low cardiorespiratory and muscular fitness of the upper, middle, and lower body. While body mass index was more important than any other correlate to differentiate levels of upper and lower body muscular fitness during adolescence, specific characteristics of sports participation emerged as key factors to discriminate between high and low cardiorespiratory fitness and middle body muscular fitness. Other correlates, including the self-report of active recess time, active commuting to school, favorable neighborhood conditions, and limited time on screens and cellphones, were demonstrative of favorable physical fitness levels. CONCLUSIONS: Both body composition and sports-related characteristics emerged as the two most relevant factors of physical fitness in youth. Additional health benefits may be obtained from building supportive environments for sports and healthy exercise habits within the household and at different school education levels.

Limb-specific isometric and isokinetic strength in adults: The potential role of regional bioelectrical impedance analysis-derived phase angle.

BACKGROUND & AIMS: It is not yet known whether regional bioelectrical impedance (BIA) phase angle (PhA) may be informative of different types of strength performed by the lower and upper limbs, independently of lean soft tissue mass (LSTM). Using a sample of healthy adults, we aimed to examine the association and relevance of regional PhA relative to isometric and isokinetic strength of each limb. METHODS: A total of 57 participants (32.7 ± 12.9 years; 24.7 ± 3.5 kg/m2) were included in the present investigation. Regional raw BIA variables were determined using a phase-sensitive BIA device. Dual-energy X-ray absorptiometry was used to evaluate LSTM. Absolute isometric and isokinetic (i.e., 60°/s and 180°/s) strength of each limb (extension and flexion) was assessed using an isokinetic dynamometer and used to calculate relative strength. RESULTS: In absolute strength, only dominant leg PhA was associated with isometric extension strength (ß = 0.283) and isokinetic 180°/s flexion strength (ß = 0.354), regardless of LSTM (p < 0.05). In relative strength, a significant association of regional PhA was found for dominant arm flexion isometric strength (ß = 0.336), and non-dominant arm and dominant leg extension isometric strength (ß = 0.377, ß = 0.565, respectively; p < 0.05), independently of LSTM. Similarly, for isokinetic 180°/s strength, regional PhA significantly explained the variance in the relative strength of both arms and dominant leg (ß = 0.350 to 0.506), regardless of LSTM (p < 0.05). Relative isokinetic 60°/s strength was not consistently associated with regional PhA (p ≥ 0.05). CONCLUSIONS: Regional PhA significantly explained relative (isometric and 180°/s isokinetic strength of both arms and dominant leg), but not absolute muscle strength, independently of regional LSTM. Thus, after accounting for body size, regional PhA seems to have its own characteristics that explain relative strength independently of LSTM.

Functional fitness trends among older adults in Portugal between 2008 and 2018: Keeping up with a healthy aging process.

OBJECTIVES: Maintaining a healthy aging process is vital to combating and delaying the adverse health outcomes faced by the growing older adult population, where a key aspect to achieving healthy aging is the preservation of functional fitness. This study aims to present trends on the functional fitness of Portuguese older adults between 2008 and 2018 and build new normative reference standards for the Senior Fitness Battery Tests. DESIGN: Cross-sectional study. METHODS: Functional fitness was measured with the Senior Fitness Battery Tests in two national representative cohorts of the Portuguese older adult population (≥65 years) using the 2008 (n = 4712) and 2018 (n = 2717) surveys. Changes were assessed according to sex and age group. Sex and age-group normative fitness scores were developed. RESULTS: Overall findings suggested that older adults' point prevalence for arm-curl, 8-ft up-and-go, and 30-s chair sit-to-stand remained stable between 2008 and 2018, with declining trends being observed for the 6-min walk and back-scratch tests. However, results for trends varied when stratified by sex and age categories. CONCLUSIONS: Our results suggest a trend toward a stabilization of most of the functional fitness tests over the past decade, but with a critical decline in the 6-min walk test. Thus, this test should be targeted by future health-care policies. Moreover, this investigation provides new and updated normative reference standards for the Senior Fitness Battery Tests that should be used as a tool to promote a healthy aging process among Portuguese older adults.

Effects of exercise training on cancer patients undergoing neoadjuvant treatment: A systematic review.

OBJECTIVES: This systematic review aimed to analyze the effects of different exercise protocols on physical fitness (cardiorespiratory fitness, muscle strength, and body composition), quality of life, cancer-related fatigue, and sleep quality in patients with different types of cancer undergoing neoadjuvant treatment. DESIGN: Systematic review. METHOD: A comprehensive search of existing literature was carried out using four electronic databases: PubMed, Scopus, Web of Science, and Cochrane Library (published until October 19, 2022). All databases were searched for randomized controlled trials, quasi-experimental investigations, and pre-post investigations assessing the effects of exercise in cancer patients during neoadjuvant treatment. Excluded articles included multicomponent interventions, such as exercise plus diet or behavioral therapy, and investigations performed during adjuvant treatment or survivorship. The methodological quality of each study was assessed using the Physiotherapy Evidence Database (PEDro) scale. RESULTS: Twenty-seven trials involving 999 cancer patients were included in this review. The interventions were conducted in cancer patients undergoing neoadjuvant treatment for rectal (n = 11), breast (n = 5), pancreatic (n = 4), esophageal (n = 3), gastro-esophageal (n = 2), and prostate (n = 1) cancers, and leukemia (n = 1). Among the investigations included, 14 utilized combined exercise protocols, 11 utilized aerobic exercise, and two utilized both aerobic and resistance training separately. Exercise interventions appeared to improve cardiorespiratory fitness, muscle strength, body composition, and quality of life, although many investigations lacked a between-group analysis. CONCLUSION: Despite limited evidence, exercise interventions applied during neoadjuvant treatment demonstrate promising potential in enhancing cardiorespiratory fitness, muscle strength, body composition, and overall quality of life. However, a scarcity of evidence remains on the effects of exercise on cancer-related fatigue and sleep quality. Further research with high-quality randomized controlled trials is warranted.

Physical fitness trends in a nationally representative sample of Portuguese youth: What has changed from 2008 to 2018?

This investigation aimed to describe the current physical fitness (PF) status of Portuguese youth, compare secular trends from 2008 and 2018, and establish updated age- and sex-specific percentile values for distinct PF tests. In 2008 and 2018, 22 048 and 8960 children and adolescents (10-18 years) were included in two national cross-sectional investigations. PF was evaluated using the FITESCOLA® battery tests and the handgrip strength test. Independent sample t-tests and chi-squared tests were used to model the results. Weight smoothed percentile values were calculated using Cole's Lambda-Mu-Sigma (LMS) method. All analyses were weighted according to age, sex, and geographic region. In 2018, boys surpassed girls in the 20-m shuttle run, curl-ups, push-ups, standing long, and vertical jump tests, while girls performed better in the sit-and-reach (p < 0.05). The percentage of boys and girls meeting the healthy zone in the 20-min shuttle run test did not differ between 2008 and 2018 (p ≥ 0.05). In boys, a higher percentage fell in the healthy zone for the curl-up and push-up tests in 2018 compared to 2008 (85.8% vs. 83.4%, and 57.8% vs. 53.8%; p < 0.05). Girls improved their flexibility component (sit-and-reach test), with a higher percentage meeting the healthy zone in 2018 (32.6% vs. 36.9%; p < 0.05); an opposite trend was seen for boys (65.5% vs. 50.1%; p < 0.05). The present investigation provides new and updated PF percentile curves for Portuguese youth, which can be used as a general overview of the current PF state among the Portuguese young population.

Physical Activity and Sedentary Behavior in the Portuguese Population: What Has Changed from 2008 to 2018?

PURPOSE: Assessment of trends in physical activity (PA) and sedentary time (ST) is important for evaluating the effectiveness of national policies and setting goals to improve population PA. This study describes changes in measured PA and ST through motion sensors of the Portuguese population from 2008 to 2018. METHODS: PA and ST were measured with accelerometry from individuals (≥10 yr) participating in the 2008 ( n = 4 532) and 2018 ( n = 6 369) Portuguese PA Surveillance Systems. Changes were analyzed using generalized linear and logistic models adjusted for accelerometer wear time. A weight factor was applied to all analyses in order to achieve national representativeness of the present results. RESULTS: In 2018, 15.4%, 71.2%, and 30.6% of Portuguese youth, adults, and older adults met the PA recommendations. Compared with 2008, the percentage meeting the PA guidelines increased in youth females (4.7% vs 7.7%, P < 0.05) and adult males (72.2% vs 79.4%, P < 0.05). A decrease in ST was observed for adult males, whereas ST increased in all youth. Male youth decreased the number of breaks in ST (BST per hour), whereas a favorable increase was found for both adult and older adult males and females. CONCLUSIONS: PA has remained fairly stable between 2008 and 2018 for all groups, except for youth females and adult males. For ST, a favorable decrease was observed for adult males; however, an inverse trend was found in youth. These results are relevant for policy makers to develop health care policies aimed at promoting PA and reducing ST across all age-groups.

Compensatory mechanisms from different exercise intensities in type 2 diabetes: a secondary analysis of a 1-year randomized controlled trial.

AIMS: This investigation aimed to determine the effect of different intensities of training on non-exercise physical activity (NEPA) and estimated thermogenesis (NEAT) from a 1-year exercise randomized controlled trial (RCT) in individuals with type 2 diabetes mellitus (T2DM) on non-training days. Additionally, changes in NEPA and estimated NEAT in those who failed (low-responders) or succeeded (high-responders) in attaining exercise-derived clinically meaningful reductions in body weight (BW) and fat mass (FM) (i.e., 6% for FM and 3% for BW) was assessed. METHODS: Individuals with T2DM (n = 80) were enrolled in a RCT with three groups: resistance training combined with moderate-intensity continuous training (MICT) or high-intensity interval training (HIIT) and a control group. Of the 80 participants, 56 (completed data) were considered for this secondary analysis. NEPA and estimated NEAT were obtained by accelerometry and body composition through dual-energy X-ray absorptiometry. RESULTS: After adjustments, no time*group interactions were found for estimated NEAT in the MICT (ß = - 5.33, p = 0.366) and HIIT (ß = - 5.70, p = 0.283), as well as for NEPA in the MICT (ß = - 452.83, p = 0.833) and HIIT (ß = - 2770.76, p = 0.201), when compared to controls. No compensatory changes in NEPA and estimated NEAT were observed when considering both low-responders and high-responders to FM and BW when compared to controls. CONCLUSIONS: Both MICT and HIIT did not result in any compensatory changes in estimated NEAT and NEPA with the intervention on non-training days. Moreover, no changes in estimated NEAT and NEPA were found when categorizing our participants as low-responders and high-responders to FM and BW when compared to controls. Trial registration clinicaltrials.gov ID. NCT03144505.

Breaking-Up Sedentary Behavior and Detraining Effects on Glycemic Control: A Randomized Crossover Trial in Trained Older Adults.

In a randomized crossover trial, we examined the effects of interrupting sedentary behavior on glycemic control in trained older adults, before and after 2 weeks of detraining. Fourteen participants (65-90 years old) completed two 7-hr conditions before and after 2 weeks of detraining: (a) uninterrupted sitting (SIT) and (b) sitting plus 2 min of moderate-intensity activity every 30 min (INT). Both before and after detraining, no differences were observed for 7-hr glucose area under the curve (7 hr AUC) and mean glucose between sitting plus 2 min of moderate-intensity activity and uninterrupted sitting conditions. After detraining and for the SIT condition, higher values of 7-hr AUC (p = .014) and mean glucose (p = .015) were observed, indicating worsened glycemic control. No changes were observed in INT condition between both time points. Frequent interruptions in sedentary behavior had no effect on glycemic control, prior to or after detraining. Even so, older adults experiencing a short-term detraining period should avoid prolonged bouts of sedentary behavior that may jeopardize their glycemic control.

Development and validation of bioelectrical impedance prediction equations estimating regional lean soft tissue mass in middle-aged adults.

BACKGROUND/OBJECTIVES: Bioelectrical impedance (BIA) whole-body and regional raw parameters have been used to develop prediction models to estimate whole-body lean soft tissue (LSTM), with less attention being given to the development of models for regional LSTM. Therefore, we aimed to develop and validate BIA-derived equations predicting regional LSTM against dual x-ray absorptiometry (DXA) in healthy adults. SUBJECTS/METHODS: 149 adults were included in this cross-sectional investigation. Whole-body and regional LSTM were assessed by DXA, and raw bioelectrical parameters of distinct body regions were measured using a 50 kHz phase sensitive BIA analyzer. BIA-derived equations were developed using a stepwise multiple linear regression approach in 2/3 of the sample and cross-validated in the remaining sample. RESULTS: Slopes and intercepts of predicted LSTM and DXA measured LSTM did not differ from 1 and 0, respectively, for each region (p ≥ 0.05), with the exception for the trunk (p < 0.05). The BIA-derived equations exhibited a strong relationship (p < 0.001) between the predicted and measured LSTM for each of the following body regions: right and left arms (R = 0.94; R = 0.96), right and left legs (R = 0.88; R = 0.88), upper body (R = 0.96), lower body (R = 0.89), right and left sides of the body (R = 0.94; R = 0.94), and trunk (R = 0.90). Agreement analyses revealed no associations between the differences and the means of the predicted and DXA-derived LSTM. CONCLUSION: The developed BIA-derived equations provide a valid estimate of regional LSTM in middle-aged healthy adults, representing a cost-effective and time-efficient alternative to DXA for the assessment and identification of LSTM imbalances in both clinical and sport-specific contexts.

A hierarchy of correlates for objectively measured physical activity, sedentary time, and physical fitness in older adults: A CHAID analysis.

The aging process reflects, in many cases, not only a decline in physical activity (PA) and physical fitness (PF), but also an increase in overall levels of sedentary time (ST). In order to hierarchically identify the most powerful correlates related to low and high levels of objectively assessed PA, ST, and PF during the late adulthood, a total of 2666 older adults were cross-sectionally evaluated. Multidimensional correlates were obtained through interview. Using chi-squared automatic detection analysis to identify the cluster of correlates with most impact on PA (<21.4 min/day), ST (≥8 h/day), and PF (<33.3th percentile), was found that the most likely subgroup to be physically inactive consisted of widowers not owning a computer and sport facilities in the neighbourhood (94.7%), while not being widowed, reporting to have a family that exercises and a computer at home (54.3%) represented the subgroup less likely to be inactive. Widowers without sidewalks in the neighbourhood were the most sedentary group (91.0%), while being a married woman and reporting to have space to exercise at home (40%) formed the most favourable group of correlates regarding ST. Men reporting a financial income <500€ and physical problems frequently formed the group with the lowest PF level (70.3%). In contrast, the less likely subgroup to have low levels of PF level consisted of having a financial income ≥1000€ and a computer at home (3.4%). Future interventions should target widowers with limited accessibility to computer and urban/sport-related infrastructures, as well as impaired older adults with low financial income.HighlightsChi-squared automatic interaction detection was used to identify and hierarchise correlates of objectively measured physical activity, sedentary time, and fitness.Widowers not having a computer at home and sport facilities in the neighbourhood were the most likely to be physically inactive, while not being widowed, having a family that exercises and a computer at home represented the subgroup less likely to be physically inactive.The most likely to be classified as sedentary were widowers without sidewalks in the neighbourhood, while the most favourable group of correlates regarding ST was formed by married women and reporting to have space to exercise at home.Individuals with a low financial income and physical problems comprised the population subgroup with the lowest PF levels, while having a medium-high financial income and a computer at home represented the less likely subgroup to have low levels of PF.

Relative Sit-to-Stand Muscle Power Predicts an Older Adult's Physical Independence at Age of 90 Yrs Beyond That of Relative Handgrip Strength, Physical Activity, and Sedentary Time: A Cross-sectional Analysis.

OBJECTIVES: Muscle power is important for an older adult's physical independence and can be easily estimated using the sit-to-stand test. This investigation aimed to assess whether muscle power estimated using the sit-to-stand test could identify older adults at risk of losing physical independence beyond handgrip strength, physical activity, and sedentary time and to develop minimal sit-to-stand power thresholds. DESIGN: Physical independence was assessed cross-sectionally in older adults using a composite physical function questionnaire. Muscle power was calculated using the 30-sec sit-to-stand test. Muscle strength was determined using a handgrip dynamometer. Physical activity and sedentary time were assessed by accelerometry. Multiple logistic regression was used to assess the independent association between sit-to-stand power and projected physical independence ( n = 737). Receiver operator characteristic curves were used to develop sit-to-stand power cut points ( N = 1748). RESULTS: Sit-to-stand power proved to be the best predictor of physical independence in later life regardless of handgrip strength, physical activity, and sedentary time (standardized B = 0.45, -0.02, 0.12, -0.28, respectively). Sex- and age-specific cutoffs for sit-to-stand power had good discriminatory ability (area under the curve = 0.75-0.78 [women], 0.76-0.82 [men]). CONCLUSIONS: Sit-to-stand power can be used as a simple and practical screening tool to assess an older adult's future physical independence.

Sedentary behaviours and their relationship with body composition of athletes.

ABSTRACTDuring the recovery period, athletes present high sedentary behaviour (SB). In non-athletes, there is a direct relationship between SB and obesity. However, little is known about this relationship in athletes. We hypothesized that different types of SB entail different associations with body composition outcomes.We examined the associations between different types of SB and body composition outcomes in 135 athletes (70 males) aged 21.3 ± 3.9 years old. Dual-energy X-ray absorptiometry was performed to assess fat mass (FM), fat-free mass (FFM) and trunk fat mass (TFM). A validated SB questionnaire (PACE) was used to estimate total SB and specific sedentary pursuits on an average day. Multiple linear regression analyses were performed, adjusting for age, sex, weekly training time, years of sport practice, and sport type.A positive association was found for total SB and total screen time with %TFM (ß = 0.220, p = 0.038 and ß = 0.319, p = 0.040, respectively), while an inverse association was found for %FFM (ß = -0.214, p = 0.042 and ß = -0.310, p = 0.026). A higher total screen time was related with a higher %FM (ß = 0.283, p = 0.035). With a much stronger effect size, cell phone screen time was positively related with %FM (ß = 1.447, p = 0.001).There is still debate whether high levels of physical activity can fully counteract the harms of SB. These findings suggest that SB, particularly cell phone screen time, can compromise athletes' body composition, regardless of weekly training time. Sport federations and coaches may improve athletes' body composition by targeting specific sedentary pursuits, i.e. total screen time and cell phone screen time, during athletes' recovery time.Highlights Even in athletes, SB can compromise total and regional body composition regardless of high training time.Screen time, specifically cell phone screen time seems to be the sedentary pursuit to target in athletes.Sport federations and coaches must control SB during athletes' recovery time.

Interindividual Variability in Fat Mass Response to a 1-Year Randomized Controlled Trial With Different Exercise Intensities in Type 2 Diabetes: Implications on Glycemic Control and Vascular Function.

Purpose: Little is known about the interindividual variability in fat mass (FM) loss in response to high-intensity interval training (HIIT) and moderate continuous training (MCT) in individuals with type 2 diabetes mellitus (T2DM). Moreover, the impact on health-related outcomes in those who fail to reduce FM is still unclear. The aims of this investigation were (1) to assess if the individuals with T2DM who FM differed across MCT, HIIT, and control groups over a 1-year intervention and (2) to assess the changes on glycemic control and vascular function in the exercising patients who failed to lose FM. Methods: Adults with T2DM were randomized into a 1-year intervention involving a control group (n=22), MCT with resistance training (RT; n=21), and HIIT with RT (n=19). FM was assessed using dual-energy X-ray absorptiometry and a change in total body FM above the typical error was used to categorize FM responders. Glycemic control and vascular stiffness and structure were assessed. A chi-square test and generalized estimating equations were used to model the outcomes. Results: Both MCT (n=10) and HIIT (n=10) had a similar proportion of individuals who were categorized as high responders for FM, with the percent change in FM on average -5.0±9.6% for the MCT and -6.0±12.1% for the HIIT, which differed from the control group (0.2±7.6%) after a 1-year intervention (p<0.05). A time-by-group interaction for carotid artery intima-media thickness (cIMT) (p for interaction=0.042) and lower-limb pulse wave velocity (LL PWV; p for interaction=0.010) between those categorized as low FM responders and the control group. However, an interaction was observed between the high responders for FM loss and controls for both brachial and carotid hemodynamic indices, as well as in cIMT, carotid distensibility coefficient, carotid beta index, and LL PWV (p for interactions <0.05). No interactions were found for glycaemic indices (p for interaction >0.05). Conclusion: Our results suggest that the number of FM responders did not differ between the MCT or HIIT, compared to the control, following a 1-year exercise intervention in individuals with T2DM. However, low responders to FM may still derive reductions in arterial stiffness and structure. Clinical Trial Registration: Comparing Moderate and High-intensity Interval Training Protocols on Biomarkers in Type 2 Diabetes Patients (D2FIT study) - number: NCT03144505 (https://clinicaltrials.gov/ct2/show/NCT03144505).

A hierarchy of correlates impacting adults' sensor-based physical activity and sedentary time.

Investigation into correlates across all levels of the socio-ecological model predictive of objectively measured physical activity has rarely been assessed in adults. While considering a diversity of correlates, we determined which correlates best predict sensor-based moderate-to-vigorous physical activity (MVPA) and sedentary-time (ST) in adults. A Chi-squared Automatic Interaction Detection algorithm was used to hierarchize the correlates associated with high ST (≥66.6thpercentile) and sufficient MVPA (≥150 min/week) in 865 adults. The main correlate predictive of being active was currently partaking in sport/exercise. The following relevant correlates were being male for the exercisers and having trees in the neighbourhood for the non-exercisers. The final correlate to boost male exercisers' MVPA was having lots of shops in the neighbourhood and not having television in the bedroom for women. The primary correlate for high ST was job activity level, with individuals having highly active jobs being less likely to exhibit high levels of ST; being single, male, and a former athlete also increased the chances of being highly sedentary. To increase adults' MVPA, promotion of sport participation, neighbourhood landscape planning, shop availability, as well as limiting television in the bedroom must be prioritized. For counteracting ST, increasing workplace activity level is warranted.

Criterion validity of a single-item question for assessment of daily breaks in sedentary time in adults.

BACKGROUND: As the implementation of sensor-based assessment for sedentary time (ST) and physical activity (PA) has practical limitations when applied on a large-scale, most studies rely on subjective data. We aimed to examine the criterion validity of a single-item question to assess daily breaks in ST and other PA-related outcomes for the first time using sensor-based data as the criterion. METHODS: In a sample of 858 adults, breaks in ST and other PA-related parameters were assessed through sensor-based accelerometry and subjective data, which included a comprehensive questionnaire with a specific question ('During the day, do you usually sit for a long time in a row or interrupt frequently?') with a three-level closed answer. The Spearman's rank correlation coefficient was used to determine the agreement between the single-item question and sensor-based data. RESULTS: Positive correlations were found for self-reported breaks in ST with sensor-based breaks in ST in both women (ρ=0.37; 95% CI=0.29-0.44) and men (ρ=0.15; 95% CI=0.04-0.26). Self-reported breaks in ST were inversely correlated with ST in women (ρ =-0.33; 95% CI=-0.40 to 0.25). For both sexes, self-reported breaks in ST showed a positive correlation with light-intensity PA (ρ=0.39; 95% CI=0.31-0.46 women; ρ=0.13; 95% CI=0.02-0.24 men), however, positive correlations between self-reported breaks in ST and moderate-to-vigorous PA (ρ=0.13; 95% CI=0.02-0.24) were found only in men. CONCLUSIONS: Our single-item question can be used as an indication for ranking people's breaks in ST during the waking day, although acknowledging that some misclassification will occur, especially in men. There must be an effort to include this question in future national and international surveys to replicate these findings.

Physical activity moderates the effect of sedentary time on an older adult's physical independence.

BACKGROUND/OBJECTIVES: Moderate-to-vigorous physical activity (MVPA) and breaks in sedentary time (BST) have been proposed as viable solutions to improve an older adult's physical independence, whereas sedentary time (ST) has been associated with detrimental effects. We sought to assess the joint effects of ST, BST, and MVPA on the physical independence of older adults and determine whether and to what extent the ST relationship with physical independence is moderated by MVPA and/or BST. DESIGN: Cross-sectional. SETTING: Laboratory of Exercise and Health, Faculty of Human Kinetics. PARTICIPANTS: Older adults (≥65 years old) from the national surveillance system in Portugal (n = 821). MEASUREMENTS: Physical activity and ST were assessed by accelerometry. Physical independence was assessed using a 12-item composite physical function (CPF) questionnaire. Multiple linear regression was used to model the outcomes. RESULTS: Higher ST was related to lower CPF score (ß = -0.01, p < 0.0001), whereas higher MVPA was related to better CPF score (ß = 0.02, p < 0.0001). BST was not related to physical independence after accounting for MVPA and ST (ß = 0.03, p = 0.074). MVPA had a moderating effect on the relationship of ST with CPF score (p < 0.0001), where MVPA ≥36.30 min/day ameliorated the significant inverse relationship between ST and CPF. Engaging in ≥107.78 of MVPA resulted in ST having a significant positive relationship with CPF score. No moderation effect was found for BST (p > 0.05). CONCLUSION: Regardless of the time spent in MVPA and BST, ST was inversely related to CPF. However, MVPA was found to be a moderator of the relationship between ST and physical independence, such that engaging in at least 36 min/day of MVPA may blunt the negative effects of ST. At high levels of MVPA (≥108 min/day), having some ST may actually provide some benefit to an older adult's ability to maintain physical independence.

Sedentary patterns are associated with BDNF in patients with type 2 diabetes mellitus.

PURPOSE: Exercise is beneficial to type-2 diabetes-mellitus (T2DM), and there is evidence showing that one of those benefits include a higher expression of brain-derived neurotrophic factor (BDNF), which has been implicated in improving fat oxidation and cognitive development. The deleterious effect of prolonged sedentary time (ST) on BDNF levels has never been examined in patients with T2DM. Our goal was to analyse the associations for sedentary patterns [i.e. breaks in ST per sedentary hour (BST-ST) and bouts of sedentary time (BSB) of different length] with BDNF in patients with T2DM, independent of moderate-to-vigorous physical activity (MVPA) and cardiorespiratory fitness (CRF). METHODS: Sample included 80 patients (38 women) with T2DM (58.3 ± 7.8 years). ST and MVPA were assessed by accelerometry (ActiGraph, GT3X + model), BDNF by blood collection and plasma quantification using commercial enzyme-linked immunosorbent assay kits, and CRF was determined using a Bruce protocol to exhaustion, on a motorized treadmill. RESULTS: Positive associations for BST-ST (ß = 0.155; p = 0.007) with BDNF, and negative associations for BSB longer than 15 min with BDNF were found (ß = - 0.118; p = 0.049). Neither MVPA nor cardiorespiratory fitness eliminated the associations for BST-ST with BDNF, but MVPA eradicated the associations between BSB > 15 min and BDNF. CONCLUSIONS: Our findings suggest that interrupting ST and especially avoiding longer sedentary periods (> 15 min) may be beneficial for BDNF plasma abundance that may influence metabolic and cognitive functioning of patients with T2DM, especially for the ones presenting lower MVPA levels. TRIAL REGISTRATION: May 5, 2017, ClinicalTrials.govID:NCT03144505.

The impact of 2 weeks of detraining on phase angle, BIVA patterns, and muscle strength in trained older adults.

BACKGROUND: An intermission in the training routine, in which older adults refrain from regular structured exercise, may have deleterious effects on muscle performance and bioelectric phase angle (PhA), which is a predictive marker for cellular integrity. PURPOSE: To determine the effects of a 2-week detraining period on PhA and muscular strength (MS) in trained older adults. METHODS: A total of 14 trained older adults (6 females) aged ≥65 years (77.2 ± 6.6) were assessed at baseline (i.e. trained condition) and after 2 weeks of detraining, where they refrained from their usual participation in structured exercise sessions. Whole-body resistance (R), reactance (Xc), and PhA were assessed using bioelectrical impedance analysis (BIA, single frequency, 50 kHz ± 1%, NutriLab, Akern). MS was assessed on both lower and upper limbs under isometric conditions. Differences between moments were examined using ANOVA for repeated measures, while adjusting for sex. Bioimpedance vector analysis (BIVA) was performed to evaluate changes in cellular function and body fluid content. RESULTS: Detraining resulted in declines in PhA (-4.34%) (p = 0.017). There was a significant difference in the mean impedance vectors from baseline to post-detraining (p < 0.05), which were driven by decreases in reactance (Xc) relative to height (Xc/H) with little change in resistance (R) relative to height (R/H) for both males and females. No differences were found in MS for both the leg press (p = 0.992) and bench press (p = 0.166) tests. CONCLUSION: A detraining period as short as 2-weeks is enough to cause alterations in the bodies bioelectrical properties, resulting in detrimental changes in PhA, due to alterations in cellular integrity, but not in MS. These results highlight the importance of maintaining structured exercise sessions in older adults, and reinforce the potential role of PhA as a sensitive predictor to detect acute changes in muscle cell integrity following alterations in exercise training.

Whole body and regional phase angle as indicators of muscular performance in athletes.

Bioelectrical impedance analysis (BIA)-derived phase angle (PhA) has been used to assess cellular health in various populations, but its usefulness as a tool for measuring muscular performance in adult athletes has not been extensively investigated. Our investigation examined the association of whole-body (WB) PhA with muscular performance in 117 adult athletes from different sports and additionally assessed whether regional PhA was a better indicator of muscular performance compared to WB, while accounting for lean soft tissue (LST). Muscular performance was assessed with handgrip strength and countermovement jump power. WB and regional PhA and LST were obtained by BIA and dual-energy x-ray absorptiometry, respectively. Multiple linear regression was used to model outcomes, while adjusting for LST. WB PhA was positively associated with relative power and relative and absolute strength (p < 0.05), irrespective of LST. Regional PhA measures explained similar amounts of variance in absolute and relative power and strength as that of WB PhA after accounting for age, sex, height, and sport type (lower limb adj R2 = 0.42, 0.60 for power; upper limb adj R2 = 0.38, 0.74 for strength; WB adj R2 = 0.44, 0.63 and 0.38, 0.75 for power and strength, respectively). Only upper limb PhA was related with strength (p < 0.05) after accounting for upper limb LST. PhA may have the potential to be used as a marker of functional muscle mass, which is important when it comes to assessing muscular performance of athletes. Regional measures of PhA do not provide a better indicator of regional strength or power when compared to WB PhA.