Ternary composites of poly(vinylidene fluoride-co-hexafluoropropylene) with silver nanowires and titanium dioxide nanoparticles as separator membranes for lithium-ion batteries

In the realm of polymer composites, there is growing interest in the use of more than one filler for achieving multifunctional properties. In this work, a composite separator membrane has been developed for lithium-ion battery application, by incorporating conductive silver nanowires (AgNWs) and titanium dioxide (TiO2) nanoparticles into a poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) polymer matrix. The composite membranes were manufactured by solvent casting and thermally induced phase separation, with total filler content varying up to 10 wt%. The ternary composites composites present improved mechanical characteristics, ionic conductivity and lithium transfer number compared to the neat polymer matrix. On the other hand, the filler type and content within the composite has little bearing on the morphology, polymer phase, or thermal stability. Once applied as a separator in lithium-ion batteries, the highest discharge capacity value was obtained for the 5 wt% AgNWs/5 wt% TiO2/PVDF-HFP membrane at different C-rates, benefiting from the synergetic effect from both fillers. This work demonstrates that higher battery performance can be achieved for next-generation lithium-ion batteries by using separator membranes based on ternary composites.

Resistance training effects on pubertal children with a risk of developing pediatric dynapenia

PURPOSE

Many modern-day children are at risk of pediatric dynapenia (muscle weakness). We examined the effects of a 12-week resistance training (RT) program on neuromuscular function and body composition parameters in pubertal children with a risk of dynapenia.

METHODS

Twelve children (13.4 ± 0.9 y) with dynapenia performed a progressive RT program consisting of knee extension and flexion, bench press, abdominal crunch, back extension, lateral pull-down, elbow flexion, and upright row (1-2 sets of 10-15 repetitions/exercise) twice/week for 12 weeks. Outcome measures included one-repetition maximum (1-RM) strength, maximal voluntary isometric contraction (MVIC) torque, rate of torque development (RTD), electromyographic (EMG) activity, muscle thickness (MT), muscle quality (MQ) assessed by echo intensity (MQEI) of the knee extensors and specific tension of MVIC torque to thigh fat-free mass (MQST), and total and regional body and bone composition assessed by dual-energy X-ray absorptiometry. Changes in the measures before and after the 12-week RT and associations among the measures were analyzed by linear mixed models.

RESULTS

Significant (p < 0.05) increases in 1-RM (63.9 ± 4.5%), MVIC torque (16.3 ± 17.8%), MT (18.8 ± 5.5%) and MQ (MQEI: -25.9 ± 15.2%; MQST: 15.1 ± 18.8%;) were evident from pre- to post-training. Total fat-free mass (FFM) increased by 2.3 ± 3.2% from baseline (p = 0.01), but no changes (p > 0.05) in the other measures were observed. Significant (p < 0.05) associations between the changes in 1-RM and/or MVIC torque and the changes in quadriceps MT, MQEI, MQST and total body FFM were evident.

CONCLUSIONS

The 12-week RT was effective for improving neuromuscular and body composition parameters, and thereby reversed the risk of pediatric dynapenia.

Effects of resistance training on muscle strength in adults with haemophilia: A systematic review and meta-analysis

INTRODUCTION

Although resistance training is frequently prescribed for people with haemophilia (PWH), no previous meta-analyses have quantified the effect of this intervention on muscle strength, nor the implications of the intervention's modality and duration.

AIM

(1) To determine the effects of resistance training on muscle strength in adults with haemophilia; (2) To determine the most effective duration and modality among the exercise protocols.

METHODS

A systematic search from inception until 28 November 2023 was conducted in PubMed, Embase, Web of Science, CENTRAL and CINAHL databases. We included randomised controlled trials or before-after studies that involved resistance training without other physiotherapy co-interventions. Study selection, data extraction and risk of bias assessment were independently performed by two reviewers. Disagreements were resolved in consultation with a third author. The level of evidence was determined according to the GRADE methodology.

RESULTS

Seven studies were included. Measurements of knee extensor strength and elbow extensor strength were included in the meta-analysis. Subgroup analysis showed significant effects for both elastic resistance protocols (SMD: 0.54; 95% CI: 0.02-1.07) and conventional training (isometric and weight-based equipment) (SMD: 0.88; 95% CI: 0.50-1.25), demonstrating small and moderate effect sizes respectively. Additionally, both protocols of duration 5-7 weeks (SMD: 1.16, 95% CI: 0.63-1.69) as well as those of duration ≥8 weeks (SMD: 0.57, 95% CI: 0.20-0.94) showed a significant difference.

CONCLUSION

Resistance training is effective in improving muscle strength of the knee and elbow extensors in PWH. Both elastic resistance and conventional training show benefits.

30-sit-to-stand power is a better tool than isometric knee extensor strength to detect motor impairment in people with haemophilic arthropathy

INTRODUCTION

Regular assessment of motor impairments is crucial in people with haemophilic arthropathy (PwHA). This study aimed to determine if there are differences in 30-seconds sit-to-stand (30-STS) power and maximal voluntary isometric contraction (MVIC) of the knee extensors between PwHA and healthy control group (CG). The secondary aims were to investigate the correlation between 30-STS power and MVIC of knee extensors with clinical characteristics and to assess their effectiveness in identifying motor impairment in PwHA.

METHODS

A cross-sectional study was conducted by collecting data from PwHA (n = 17) and a sedentary CG (n = 15). MVIC (torque) and 30-STS power were normalised to body mass. Correlation analysis and simple linear regression adjusted for age were used to assess the association between tests and clinical variables. Using z-scores derived from the mean and standard deviation of the CG, we compared the MVIC and the 30-STS power in PwHA.

RESULTS

PwHA showed lower MVIC and 30-STS power compared to CG (p < .001; large effect size d > .8). Lower 30-STS power was associated with greater joint impairment and greater fear of movement, whereas MVIC showed no association with clinical variables. 30-STS power showed a lower z-score compared to MVIC (p < .001). In addition, 30-STS power detected 47% of PwHA with motor impairment compared to 0% for MVIC (p = .002).

CONCLUSIONS

Our results suggest that 30-STS power may be more effective than knee extensors MVIC in detecting motor impairment in PwHA. Consequently, lower limb skeletal muscle power, rather than maximum knee extensor strength, appears to be more affected in PwHA.

Reduction and recovery of self-sustained muscle activity after fatiguing plantar flexor contractions

PURPOSE

Persistent inward calcium and sodium currents (PICs) are crucial for initiation and maintenance of motoneuron firing, and thus muscular force. However, there is a lack of data describing the effects of fatiguing exercise on PIC activity in humans. We simultaneously applied tendon vibration and neuromuscular electrical stimulation (VibStim) before and after fatiguing exercise. VibStim induces self-sustained muscle activity that is proposed to result from PIC activation.

METHODS

Twelve men performed 5-s maximal isometric plantar flexor contractions (MVC) with 5-s rests until joint torque was reduced to 70%MVC. VibStim trials consisted of five 2-s trains of neuromuscular electrical stimulation (20 Hz, evoking 10% MVC) of triceps surae with simultaneous Achilles tendon vibration (115 Hz) without voluntary muscle activation. VibStim was applied before (PRE), immediately (POST), 5-min (POST-5), and 10-min (POST-10) after exercise completion.

RESULTS

Sustained torque (Tsust) and soleus electromyogram amplitudes (EMG) measured 3 s after VibStim were reduced (Tsust: -59.0%, p < 0.001; soleus EMG: -38.4%, p < 0.001) but largely recovered by POST-5, and changes in MVC and Tsust were correlated across the four time points (r = 0.69; p < 0.001). After normalisation to values obtained at the end of the vibration phase to control for changes in fibre-specific force and EMG signal characteristics, decreases in Tsust (-42.9%) and soleus EMG (-22.6%) remained significant and were each correlated with loss and recovery of MVC (r = 0.41 and 0.46, respectively).

CONCLUSION

The parallel changes observed in evoked self-sustained muscle activity and force generation capacity provide motivation for future examinations on the potential influence of fatigue-induced PIC changes on motoneuron output.

Powerpenia Should be Considered a Biomarker of Healthy Aging

To identify biomarkers that precede the decline of human function and independence during the lifespan, two important concepts have been introduced in recent decades: sarcopenia and dynapenia. While the former is originally focused on skeletal muscle loss, the latter is on maximal strength loss. Although the dynapenia concept implies the inclusion of skeletal muscle power, in practical terms, this has not been specifically addressed. For instance, only 2 out of 220 studies published between 2008 and 2023 have directly measured muscle power to classify individuals with dynapenia. As previous studies have shown a greater relevance of skeletal muscle power in healthy aging, we hereby propose the introduction of the term "powerpenia" to specifically reflect the loss of skeletal muscle power along lifespan, but also with disease and/or physical inactivity. Together with sarcopenia and dynapenia, we contend that powerpenia should be considered a biomarker of healthy aging.

Chronic Effects of Different Intensities of Power Training on Neuromuscular Parameters in Older People: A Systematic Review with Meta-analysis

BACKGROUND

Power training (PT) has been shown to be an effective method for improving muscle function, including maximal strength, measured by one-repetition maximum (1RM), and power output in older adults. However, it is not clear how PT intensity, expressed as a percentage of 1RM, affects the magnitude of these changes. The aim of this systematic review (International prospective register of systematic reviews-PROSPERO-registration: CRD42022369874) was to summarize the evidence from randomized clinical trials (RCT) assessing the effects of low-intensity (≤ 49% of 1RM) and moderate-intensity (50-69% of 1RM) versus high-intensity (≥ 70% of 1RM) PT on maximal power output and maximal strength in older adults.

METHODS

We included RCTs that examined the effects of different intensities of power training on maximum strength and power output in older people. The search was performed using PubMed, LILACS, Embase, and Scopus. Methodological quality was assessed using the preferred reporting items for systematic reviews and meta-analyses (PRISMA 2020 statement checklist), and the quality of evidence was determined using the PEDro scale. Data were analyzed using standardized mean differences (SMD) with a 95% confidence interval (CI), and random effects models were used for calculations. A significance level of p ≤ 0.05 was accepted.

RESULTS

Three RCTs assessing 179 participants, all of high methodological quality, were included. There were no significant differences between different PT intensities in terms of power output gains for leg press [SMD = 0.130 (95% CI - 0.19, 0.45), p = 0.425] and knee extension exercises [SMD: 0.016 (95% CI - 0.362, 0.395), p = 0.932], as well as leg press 1RM increases [SMD: 0.296 (95% CI - 0.03, 0.62); p = 0.072]. However, high-intensity PT (70-80% of 1RM) was significantly more effective than low-intensity PT in increasing 1RM for knee extension exercise [SMD: 0.523 (95% CI 0.14, 1.91), p = 0.008].

CONCLUSIONS

PT performed at low-to-moderate intensities induces similar power gains compared to high-intensity PT (70-80% of 1RM) in older adults. Nonetheless, the influence of PT intensity on lower-limb strength gains seems to be dependent on the assessed exercise. Cautious interpretation is warranted considering the inclusion of only three studies.

Effects of a Short-Term Detraining Period on the Strength Deficit and Functional Performance of Highly Trained Soccer Players

ABSTRACT

Loturco, I, Grazioli, R, Veeck, F, Nakamura, FY, Inácio, M, Schons, P, Preissler, A, Pinto, RS, Pereira, LA, McGuigan, MR, and Cadore, EL. Effects of a short-term detraining period on the strength deficit and functional performance of highly trained soccer players. J Strength Cond Res 37(10): 2058-2063, 2023-The aim of this study was to examine the effects of a 4-week detraining period on the neuromuscular performance of highly trained soccer players. Pre and post detraining, 18 adult soccer players (age: 27 ± 4.9 years; height: 180.2 ± 7.1 cm; body mass [BM]: 78.9 ± 7.6 kg) performed vertical jumps, 20-m linear sprints, curve sprint and change of direction speed tests, and a progressive loading test in the half-squat exercise with loads corresponding to 50, 100, and 150% of the players' BM to assess the peak-force (PF), mean power (MP), and strength-deficit (SDef). Pre and post differences in the variables of interest were analyzed using paired t -tests and effect sizes (ES). No significant changes were detected for vertical jumping height and sprint times. Higher PF at 50 and 100% BM and lower SDef were shown when comparing pre- and postassessments (ES = 0.66, 0.68, 0.55; p = 0.018, 0.016, and 0.046, respectively). The MP at 50 and 100% BM increased significantly after the detraining phase (ES = 0.56, 0.82; p = 0.049 and 0.007, respectively). The results indicate that these athletes were able to maintain and achieve satisfactory levels of performance after a short period of training cessation. Interestingly, some strength- and power-derived parameters improved significantly after short-term detraining, which may have important implications for training programs aimed at maximizing speed and power performance. It is recommended that coaches test their players not only at the beginning but also at the end of the season, to better evaluate variations in performance and thus create more efficient and tailored training strategies.

Biceps Femoris Fascicle Behavior during Submaximal and Maximal Slow Speed Contractions

PURPOSE

The present study compared the effects of contraction intensity (submaximal vs maximal) and mode (concentric vs eccentric) on biceps femoris long head (BFlh) fascicle lengthening, rotation, and architectural gear ratio at long and short muscle lengths.

METHODS

Data were captured from 18 healthy adults (10 men and 8 women) without history of right hamstring strain injury. BFlh fascicle length ( Lf ), fascicle angle (FA), and muscle thickness (MT) were assessed in real time using two serially aligned ultrasound devices while submaximal and maximal concentric and eccentric isokinetic knee flexions were performed at 30°·s -1 . Ultrasound videos were exported and edited to create a single, synchronized video, and three fascicles were analyzed through the range of motion (10° to 80°). Changes (Δ) in Lf , FA, MT, and muscle gear at long (60° to 80° knee angle; 0° = full knee extension) and short (10° to 30°) muscle lengths and across the full knee flexion range were measured and compared.

RESULTS

Greater Δ Lf was observed at long muscle length ( P < 0.001) during both submaximal and maximal eccentric and concentric contractions. When the full length range was analyzed, a slightly greater ΔMT was observed in concentric contractions ( P = 0.03). No significant differences between submaximal and maximal contractions were observed for Δ Lf , ΔFA, or ΔMT. No changes were detected in the calculated muscle gear between muscle lengths, intensities, or conditions ( P > 0.05).

CONCLUSIONS

Although gear ratio ranged ~1.0 to 1.1 under most conditions, the increased fascicle lengthening observed at long muscle lengths might influence acute myofiber damage risk but also speculatively play a role in chronic hypertrophic responses to training.

Effects of eccentric-emphasized leg curl intervention on muscle strength imbalance markers in professional soccer players during pre-season

BACKGROUND

The effects of strength training on muscle strength imbalance are unclear in professional soccer players. As a result, this study examined the effects of an 8-week strength training program comprising eccentric-emphasized prone leg curl adjusted according to the individual strength imbalance status.

METHODS

Ten professional soccer players (26.0 ± 3.6 yrs) participated in the study. Players who had a ≥ 10% contralateral imbalance in knee flexors eccentric peak torque (n = 6) performed two additional repetitions per set in the low-strength limb (high-volume, HV) compared to the high-strength limb (low-volume, LV). Isokinetic concentric knee extension and concentric and eccentric knee flexion peak torque (PT) and derived contralateral imbalances and conventional and functional hamstring-to-quadriceps ratios (H:Q) were assessed at baseline and after 8 weeks. Differences at baseline were assessed using paired-sample T-tests, and a two-way (limb x time) repeated measures analysis of covariance (ANCOVA) for changes over time.

RESULTS

A significant improvement in the eccentric knee flexion PT was observed in both limbs after 8 weeks (P < 0.05), with greater effects observed in the HV limb (25.0 N m, 95% CI: 15.1-34.9 N m). Significant decreases were also observed in the contralateral imbalances from concentric knee extension and flexion and eccentric knee flexion PT (P < 0.05). Differences were not observed in concentric knee extension and flexion PT (P > 0.05).

CONCLUSIONS

A short-term eccentric-emphasized leg curl intervention adjusted by the initial knee flexors eccentric strength was an efficient method to improve knee flexors strength imbalance in professional soccer players.

Chronic effect of resistance training on blood pressure in older adults with prehypertension and hypertension: A systematic review and meta-analysis

The chronic antihypertensive effect of resistance training (RT) has been widely recognized in mixed-aged populations. However, the specific effect of RT on blood pressure (BP) in older individuals (≥60 years) remains unknown. Therefore, this meta-analysis of randomized controlled trials explored the chronic effects of dynamic RT alone on BP in older people. The study followed the PRISMA statement, and the search was performed using MeSH terms "strength training", "blood pressure" and "aged" on MEDLINE (PubMed), SCOPUS, and Web of Science databases. From 1783 potential articles, 24 studies met all inclusion criteria resulting in 835 participants randomized into 26 RT interventions (n = 430) and 24 control groups (n = 405). Overall, BP reduction favoring RT was observed both in SBP (-6.88 [-10.02, -3.73] mmHg) and DBP (-3.37 [-4.71, -2.22] mmHg). Subgroup analysis revealed BP decreases in both participants with hypertension (SBP: -10.42 [-15.67, -5.17]; DBP: -3.99 [-5.76,-2.22] mmHg), and prehypertension (SBP: -4.87 [-7.76, -1.98]; DBP: -2.77 [-4.88, -0.66] mmHg). Improvement in BP was found in studies using traditional RT (free weights and machines) (SBP: -7.04 [-11.04, -3.05]; DBP: -2.60 [-3.72, -1.47] mmHg) and elastic band interventions (SBP: -2.79 [-3.72, -1.86]; DBP:-1.68 [-3.18, -0.18] mmHg). RT performed at moderate intensity (60-80 % 1RM) reduced SBP (-6.98, [-11.93, -2.03]mmHg) and DBP (-3.64 [-5.11, -2.18] mmHg). In conclusion, RT can reduce BP in older people at prehypertensive and hypertensive stage, with traditional RT performed with moderate loads leading to an effect estimate of approximately -7 mmHg for SBP and -4 mmHg for DBP.

Effects of Moderate-to-Heavy Sled Training Using Different Magnitudes of Velocity Loss in Professional Soccer Players

ABSTRACT

Grazioli, R, Loturco, I, Lopez, P, Setuain, I, Goulart, J, Veeck, F, Inácio, M, Izquierdo, M, Pinto, RS, and Cadore, EL. Effects of moderate-to-heavy sled training using different magnitudes of velocity loss in professional soccer players. J Strength Cond Res 37(3): 629-635, 2023-This study investigated the effects of a 11-week moderate-to-heavy sled training intervention with different magnitudes of velocity loss on sprint and jump performance, mechanical muscle function, and body composition in professional soccer players. Seventeen players (age 25.8 ± 4.3 years; height 180.0 ± 8.6 cm; mass 77.7 ± 9.7 kg) were randomly allocated into 2 groups, based on different magnitudes of velocity loss: 10% of velocity decrease (G10, n = 8) and 20% of velocity decrease (G20, n = 9). The velocity-based sled training consisted of 20-m resisted sprints with a progressive loading increase from 45 to 65% of body-mass throughout the intervention. Pre-intervention and postintervention sprint and jump performance, hamstring and quadriceps peak torque and isometric rate of torque development, and lower-limb lean mass measured by dual X-ray absorptiometry were assessed and compared. Two-way repeated measures analysis of variance revealed a significant time-effect for decreases in 10- and 20-m sprint times ( p = 0.018 and p = 0.033, respectively), but without a time-group interaction. The G10 showed greater beneficial effects than G20 for both 10-m (-5.5 ± 3.3%, magnitude-based inference [MBI]: possibly vs. -1.7 ± 5.9%, MBI: possibly trivial) and 20-m (-2.5 ± 2.1%, MBI: possibly vs. -1.4 ± 3.7%, MBI: likely trivial) sprint times. Moreover, there was a significant time effect for countermovement jump height and quadriceps isometric peak torque, which decreased significantly after training ( p = 0.019 and p = 0.010, respectively), with no within-group effect of time vs. group interaction for these respective outcomes. The novel velocity-based sled model proposed here, especially under lower magnitudes of velocity loss, was able to significantly improve linear sprint performance in professional soccer players.

Telehealth multicomponent exercise and health education in breast cancer patients undergoing primary treatment: rationale and methodological protocol for a randomized clinical trial (ABRACE: Telehealth)

BACKGROUND

Current guidelines emphasize cancer patients should increase their physical activity levels, encouraging physical exercise practice as a complementary therapy to mitigate adverse effects during treatment. Telehealth can be a feasible method to improve adherence and interventional support for breast cancer patients, of which most do not meet sufficient physical activity levels after diagnosis. The Adaptations to Breast Cancer and Exercise Using Telehealth (ABRACE: Telehealth) study aims to investigate the effects of a 12-week telehealth multicomponent training program plus a health education program (MTHE), compared to a health education program alone (HE), on physical and psychological outcomes in breast cancer patients undergoing treatment.

METHODS

This study is a randomized controlled trial. Women undergoing primary treatment (during or after chemotherapy) for breast cancer (stages I-III) will be randomly assigned to MTHE (twice a week) or HE (once a week). MTHE components are mobility, aerobic, balance, resistance, and flexibility home-based exercises, supervised by video call. The primary study outcome is cancer-related fatigue. The secondary outcomes are quality of life, symptoms of depression and anxiety, physical activity level, cancer-related cognitive impairment, and functional capacity. Other outcomes are adherence to interventions and a follow-up questionnaire evaluating the individual perception in motivation, lifestyle changes, and main barriers to participation. All outcomes will be remotely assessed before and after intervention. Our analysis will follow the intention-to-treat approach and per-protocol criteria, with additional sub-group analysis.

DISCUSSION

To our knowledge, this is the first randomized clinical trial in breast cancer patients using a face-to-face videoconference strategy to supervise physical exercise. Our hypothesis is of superiority for the effects of MTHE on primary and secondary outcomes compared to the effects of only the health education intervention.

TRIAL REGISTRATION

Adaptations to Breast Cancer and Exercise Using Telehealth (ABRACE: Telehealth), NCT04641377. Registered on 23 November 2021, https://clinicaltrials.gov/ct2/show/NCT04641377.

Reliability and Comparison of Sonographic Methods for In Vivo Measurement of Human Biceps Femoris Long-Head Architecture

INTRODUCTION

Biceps femoris long-head fascicle length ( Lf ), fascicle angle (FA), and muscle thickness (MT) estimates obtained across 2 d from extended field-of-view (EFOV) sonographic images were compared with those measured from a collage of single ultrasound images (to visualize entire fascicles) as well as a range of geometric equations and extrapolation methods used on single images. Both test validity and intraday reliability were determined.

METHODS

Twenty healthy adults (10 men and 10 women) were tested on two occasions (day 1 and day 2), 7 d apart at the same time of day for test-retest measurements. Ultrasound imaging was performed using EFOV and static image acquisition sequences; in the latter, four single images were acquired in-series along the muscle. From these images, Lf was assessed using seven methods: EFOV, collage, manual linear extrapolation, and four different trigonometric equations (termed equations A, B, C, and D), and FA and MT were measured in EFOV, collage, and single images.

RESULTS

Lf , FA, and MT measured on days 1 and 2 were not different ( P > 0.05) for any method, reliabilities were very high (intraclass correlation coefficient, 0.91-0.98), and correlations were strong (≥0.84). Significant correlations ( P < 0.05; r = 0.67-0.98) were found between EFOV and the other measurement techniques for Lf , FA, and MT. The collage method had the highest reliability for Lf , and highest rank order and correlation with EFOV.

CONCLUSIONS

Although the six different techniques used to estimate Lf provided values similar to EFOV, higher between-subject measurement variability was observed with trigonometric equations, and the collage method described herein provided the most accurate and reliable results and is therefore recommended for biceps femoris long-head architectural analysis when EFOV is not available.

Interindividual variability of adaptations following either traditional strength or power training combined to endurance training in older men: A secondary analysis of a randomized clinical trial

This study aimed to investigate the interindividual responses following two different concurrent training (CT) regimens in neuromuscular, cardiorespiratory and functional outcomes of older men. Thirty-five older men (65.8 ± 3.9 years) were randomly allocated into one of two CT groups: power training (PT) + high-intensity interval training (HIIT) (n = 17); or traditional strength training (TST) + HIIT (n = 18). Maximal dynamic strength (one-repetition maximum, 1RM), rate of force development at 100 milliseconds (RDF₁₀₀), countermovement jump power (CMJ), quadriceps femoris muscle thickness (QF MT), functional tests (sit-to-stand, timed-up-and-go, and stair climbing), and peak oxygen consumption (VO_2peak) were assessed pre-, post-8 and post-16 weeks of training. The Chi-squared test was used for assessing differences in the prevalence of responders (Rs), non-responders (NRs), and adverse responders (ARs). Similar prevalence of individual responses (Rs, NRs and ARs) between groups were observed after intervention in almost all outcomes: 1RM; power at CMJ; QF MT, and functional tests (P > 0.05). However, a significant difference in the distribution of Rs, NRs and ARs between groups was observed in the RFD₁₀₀ after 16 weeks (p = 0.003), with PT + HIIT group presenting high prevalence of Rs than TST + HIIT (100 % vs. 50 %). The inclusion of explosive-type of contractions in a concurrent training regime induces greater responsiveness in the RFD₁₀₀ in older men, while no differences compared to traditional strength training are observed in maximal strength, muscle size, VO_2peak, and functional performance.

The impact of skeletal muscle disuse on distinct echo intensity bands: A retrospective analysis

Echo intensity (EI) is a novel tool for assessing muscle quality. EI has traditionally been reported as the mean of the pixel histogram, with 0 and 255 arbitrary units (A.U.) representing excellent and poor muscle quality, respectively. Recent work conducted in youth and younger and older adults suggested that analyzing specific EI bands, rather than the mean, may provide unique insights into the effectiveness of exercise and rehabilitation interventions. As our previous work showed deterioration of muscle quality after knee joint immobilization, we sought to investigate whether the increase in EI following disuse was limited to specific EI bands. Thirteen females (age = 21 yrs) underwent two weeks of left knee immobilization and ambulated via crutches. B-mode ultrasonography was utilized to obtain images of the immobilized vastus lateralis. The percentage of the total number of pixels within bands of 0–50, 51–100, 101–150, 151–200, and 201–255 A.U. was examined before and after immobilization. We also sought to determine if further subdividing the histogram into 25 A.U. bands (i.e., 0–25, 26–50, etc.) would be a more sensitive methodological approach. Immobilization resulted in a decrease in the percentage of pixels within the 0–50 A.U. band (-3.11 ± 3.98%), but an increase in the 101–150 A.U. (2.94 ± 2.64%) and 151–200 A.U. (0.93 ± 1.42%) bands. Analyses of variance on the change scores indicated that these differences were large and significant (%EI0-50 vs. %EI101-150: p < .001, d = 1.243); %EI0-50 vs. %EI151-200: p = .043, d = 0.831). The effect size for the %EI51-100 versus %EI101-150 comparison was medium/large (d = 0.762), but not statistically significant (p = .085). Further analysis of the 25 A.U. bands indicated that the percentage of pixels within the 25–50 A.U. band decreased (-2.97 ± 3.64%), whereas the 101–125 (1.62 ± 1.47%) and 126–150 A.U. (1.18 ± 1.07%) bands increased. Comparison of the 50 A.U. and 25 A.U. band methods found that 25 A.U. bands offer little additional insight. Though studies are needed to ascertain the factors that may influence specific bands, changes in EI during muscle disuse are not homogeneous across the pixel histogram. We encourage investigators to think critically about the robustness of data obtained from EI histograms, rather than simply reporting the EImean value, in muscle quality research.

Environmental characteristics, nutritional and executive functions in children of 6 to 7 years

This study aimed to analyze the socio-environmental characteristics, executive and nutritional functions in children aged 6 to 7 years, from public schools in Alagoas, Brazil. A quantitative, cross-sectional and descriptive study was performed involving 64 children of the mentioned age group, from public schools located in Alagoas: Maceió, on the coast; Major Isidoro, in the hinterland and Palmeira dos Índios, in the country. Such analyzes were made through the application of neuropsychological tests and anthropometric assessment with children and food and socio-environmental surveys with their parents. As for the type of housing, 100% were made of masonry, with a bathroom present in 98.4%. All children reported with the habit of bathing in the river / lagoon, presented some pathology. There was no significant difference between cities in terms of the sociodemographic characteristics evaluated, with the same result occurring with the factors associated with the occurrence of diseases in children. The subtests of WISC-IV, were below the average in all municipalities, and the TAC and SCC were classified within the average. However, even though the ranking were divided between below average and average, it is possible to identify from the subtests of WISC-IV, that the general IQ showed a cognitive level below the average. There was also no significant difference in the anthropometric assessment (weight, height, BMI and IMCI) between the evaluated students. The average weight was 23.3 kg to 25 kg, the height between 1.23 m to 1.24 m, the BMI between 16.4 to 17; the IMCI from 2.8 to 3.0. Children were classified within the average. Regarding micronutrients (Ca, Fe, K, Mg and Na, and vitamins A, C, D, B1, B9 and B12) and calories, there was also no significant difference between the cities evaluated. The same occurred with macronutrients (proteins, carbohydrates and lipids). This study showed that in general there was no difference between the students of the three municipalities. Probably, even though they are all public schools and from different cities, children have similar social conditions.

Effects of a power training program in the functional capacity, on body balance and lower limb muscle strength of elderly with type 2 diabetes mellitus

BACKGROUND

The effects of interventions with muscle power training on balance and functionality in individuals with type 2 diabetes mellitus (T2DM) are still poorly investigated. We evaluated the efficacy of a twelve-week power training program in the functional capacity, balance and lower limb muscle power and strength of elderly with T2DM.

METHODS

Twenty-one subjects (14 women and seven men) were allocated into two groups. One of the groups (PTG) performed a power training program twice a week (N.=11; age 70.5±7.8 years old), and the other was an active control group (CG) that performed a weekly stretching session (N.=10; age 66±3.2 years old). Outcomes of interest were assessed at baseline and after 12 weeks, these included functional capacity, balance, muscle strength and power.

RESULTS

The PTG participants improved their dynamic balance (P=0.027) and decrease in the time to perform the gait speed test (P<0.001), evaluated by the short physical performance battery (SPPB). Also showed a statically significant change muscle power (P=0.034) and maximal dynamic knee extension strength (P=0.023), with increments of 24% and 34%, respectively, in comparison to the CG. Both groups showed significant changes in the performance of the five-times-sit-to-stand test (P<0.001) and the SPPB score (P=0.001).

CONCLUSIONS

The power training program was able to promote improvements in some functional parameters as on the body balance and functional capacity and muscle strength of the elderly with T2DM. The training method was effective and safe, with no adverse effects during sessions.

Effects of long-term concurrent training to failure or not in muscle power output, muscle quality and cardiometabolic risk factors in older men: A secondary analysis of a randomized clinical trial

This study investigated the effects of concurrent training performed either with repetitions to failure or not to failure in muscle power, muscle quality (MQ), peak oxygen uptake (VO_2peak), and visceral fat in older men. This is an ancillary analysis of a randomized controlled trial. 36 older men (mean age ± SD; 67.1 ± 5.1 years) were randomized into three groups: one performing repetitions to failure (RFG, n = 13), another performing repetitions not to failure and 50% of the repetitions of the RFG (NFG, n = 12), and third performing repetitions not to failure with equal training volume of the RFG (ENFG, n = 11). The training was performed twice a week for 20 weeks at intensities ranging from 65 to 80% of maximal strength. In each session, the individuals started with strengthening exercises and then performed aerobic exercise (i.e., walking) on a treadmill. The primary endpoint was change from baseline to post-20 wk of absolute and relative muscle power output during squat and countermovement jump, ultrasound measurements for MQ using quadriceps echo intensity, and visceral fat thickness, as well as their VO_2peak through a maximal incremental test on a treadmill. All training groups improved similarly and significantly jump height (ranging from 9 to 16%) and all their muscle power outcomes (mean change ranging from 2 to 7%) (P < .001). In addition, all groups significantly decreased visceral fat thickness (ranging from -11 to -21%) (P < .001), and significantly increased VO_2peak (ranging from 4 to 8%) (P < .01), with no differences between groups. No changes were observed in the MQ outcomes. Concurrent training performed using repetitions to failure or not to failure promoted similar gains in the muscle power output, aerobic capacity, and visceral fat in healthy older men.

Echo Intensity Reliability From Two Ultrasound Systems

Objective:

Echo intensity measurements are highly influenced by ultrasound system and parameters used for measurement, making comparisons of results obtained from different ultrasound machines difficult. Therefore, it is necessary to understand how reliability changes when using different ultrasound systems and parameters.

Materials and Methods:

ALOKA SSD4000 and GE LOGIQ P6 systems were used to compare rectus femoris echo intensity in 16 healthy young subjects (eight women) using different depths (D), gains (G), and frequencies (F). The following settings were adopted: ALOKA1 (D6/G30/F7.5), ALOKA2 (D6/G45/F7.5), ALOKA3 (D6/G30/F10), LOGIQ1 (D6/G50/F15), LOGIQ2 (D6/G0/F15), LOGIQ3 (D6/G0/F10), and LOGIQ4 (D6/G30/F10). Intraclass correlation coefficient, standard error of the measure, minimum difference, and Bland-Altman tests were performed to calculate reliability and agreement between systems’ settings.

Results:

ALOKA1 × LOGIQ1, ALOKA1 × LOGIQ4, and ALOKA3 × LOGIQ1 showed moderate to high ICCs and agreement on the Bland-Altman test.

Conclusion:

Echo intensity varies between systems and parameters, but reliability can be increased by adjusting the ultrasound settings.

Resistance training in breast cancer patients undergoing primary treatment: a systematic review and meta-regression of exercise dosage

BACKGROUND

Exercise is recognised as an adjunct therapy for breast cancer patients; however, little is known about the resistance training dose-response. We conducted a systematic review and meta-regression to examine the resistance training dose-response (i.e., volume and intensity) in breast cancer patients undergoing primary treatment.

METHODS

Searches in MEDLINE, CINAHL, and SPORTDiscus were conducted for studies published up to November 2019. Experimental studies that evaluated resistance-based exercise interventions in women with breast cancer undergoing primary treatment were included. Information about resistance training components, average change and change per week, as well as standardised mean difference were extracted, and used for meta-regression analysis. Outcome measures were upper and lower body muscle strength and body composition.

RESULTS

10 trials were included in the systematic review and 4 trials in the dose-response analysis. Resistance training weekly prescribed volume was inversely associated with increases in upper and lower body muscle strength (r² = 98.1-100%; p = 0.009), although there was no relationship between resistance training intensity and strength gains. There was insufficient data for the dose-response analysis of body mass index, percent body fat, and lean mass.

CONCLUSION

Low volume resistance training might be a suitable exercise recommendation for breast cancer patients undergoing primary treatment producing superior benefits for muscle strength compared to higher volume training, regardless of the training intensity. Low volume resistance training may provide a conservative and appropriate approach for breast cancer patients, allowing gradual progression and modification throughout the exercise program.