Design, Modeling, and Application of Reinforced-Airbag-Based Pneumatic Actuators with High Load and Cellular Rearrangement

Although various soft pneumatic actuators have been studied, their performance, including load capacity, has not been satisfied yet. Enhancing their actuation capability and using them to develop soft robots with high performance is still an open and challenging issue. In this study, we developed novel pneumatic actuators based on fiber-reinforced airbags as a solution to this problem, of which the maximum pressure reaches more than 100 kPa. Through cellular rearrangement, the developed actuators could bend uni- or bidirectionally, achieving large driving force, large deformation, and high conformability. Hence, they could be used to develop soft manipulators with relatively large payload (up to 10 kg, about 50 times the body self-weight) and soft climbing robots with high mobility. In this article, we first present the design of the airbag-based actuators and then model the airbag to obtain the relationship between the pneumatic pressure, external force, and deformation. Subsequently, we validate the models by comparing the simulated and measured results and test the load capacity of the bending actuators. Afterward, we present the development of a soft pneumatic robot that can rapidly climb horizontal, inclined, and vertical poles with different cross-sectional shapes and even outdoor natural objects, like bamboos, at a speed of 12.6 mm/s generally. In particular, it can dexterously transition between poles at any angle, which, to the best of our knowledge, has not been achieved before.

High-Performance Biscrolled Ni-Fe Yarn Battery with Outer Buffer Layer

The increasing demand for portable and wearable electronics has promoted the development of safe and flexible yarn-based batteries with outstanding electrochemical properties. However, achieving superior energy storage performance with a high active material (AM) load and long cycle life with this device format remains a challenge. In this study, a stable and rechargeable high-performance aqueous Ni-Fe yarn battery was constructed via biscrolling to embed AMs within helical carbon nanotube (CNT) yarn corridors. Owing to the high load of charge storage nanoparticles (NPs; above 97 wt%) and the outer neat CNT layer, the buffered biscrolled Ni-Fe yarn battery demonstrates excellent linear capacity (0.053 mAh/cm) and cycling stability (60.1% retention after 300 charge/discharge cycles) in an aqueous electrolyte. Moreover, our flexible yarn battery exhibits maximum energy/power densities of 422 mWh/cm³ and 7535 mW/cm³ based on the total volume of the cathode and anode, respectively, which exceed those reported for many flexible Ni-Fe batteries. Thus, biscrolled Ni-Fe yarn batteries are promising candidates for next-generation conformal energy solutions.

Effects of Resistance Training Performed with Different Loads in Untrained and Trained Male Adult Individuals on Maximal Strength and Muscle Hypertrophy: A Systematic Review

The load in resistance training is considered to be a critical variable for neuromuscular adaptations. Therefore, it is important to assess the effects of applying different loads on the development of maximal strength and muscular hypertrophy. The aim of this study was to systematically review the literature and compare the effects of resistance training that was performed with low loads versus moderate and high loads in untrained and trained healthy adult males on the development of maximal strength and muscle hypertrophy during randomized experimental designs. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines (2021) were followed with the eligibility criteria defined according to participants, interventions, comparators, outcomes, and study design (PICOS): (P) healthy males between 18 and 40 years old, (I) interventions performed with low loads, (C) interventions performed with moderate or high loads, (O) development of maximal strength and muscle hypertrophy, and (S) randomized experimental studies with between- or within-subject parallel designs. The literature search strategy was performed in three electronic databases (Embase, PubMed, and Web of Science) on 22 August 2021. Results: Twenty-three studies with a total of 563 participants (80.6% untrained and 19.4% trained) were selected. The studies included both relative and absolute loads. All studies were classified as being moderate-to-high methodological quality, although only two studies had a score higher than six points. The main findings indicated that the load magnitude that was used during resistance training influenced the dynamic strength and isometric strength gains. In general, comparisons between the groups (i.e., low, moderate, and high loads) showed higher gains in 1RM and maximal voluntary isometric contraction when moderate and high loads were used. In contrast, regarding muscle hypertrophy, most studies showed that when resistance training was performed to muscle failure, the load used had less influence on muscle hypertrophy. The current literature shows that gains in maximal strength are more pronounced with high and moderate loads compared to low loads in healthy adult male populations. However, for muscle hypertrophy, studies indicate that a wide spectrum of loads (i.e., 30 to 90% 1RM) may be used for healthy adult male populations.

Sprint Variables Are Associated with the Odds Ratios of Non-Contact Injuries in Professional Soccer Players

Significant evidence has emerged that a high volume of sprinting during training is associated with an increased risk of non-contact injuries in professional soccer players. Training load has been reported as a modifiable risk factor for successive injury in soccer. Sprint workload measures and non-contact injuries were recorded weekly in twenty-one professional soccer players over a one season period. Odds ratio (OR) and relative risk (RR) were calculated based on the weeks of high and low load of total distance (TD), high-speed distance (HSD), sprint distance (SPD). and repeated sprints (RS). The Poisson distribution estimated the interval time between the last injury and the new injury. The weeks with high-load levels increased the risk of non-contact injury associated with TD (OR: 4.1; RR: 2.4), HSD (OR: 4.6; RR: 2.6), SPD (OR: 6.9; RR: 3.7), and RS (OR: 4.3; RR: 2.7). The time between injuries was significantly longer in weeks of low-load in TD (rate ratio time (RRT) 1.5 vs. 4.2), HSD (RRT: 1.6 vs. 4.6), and SPD (RRT: 1.7 vs. 7.7) compared to weeks of high-load. The findings highlight an increased risk of non-contact injuries during high weekly sprint workloads. Possibly, TD, HSD, and SPD measured via a wearable inertial measurement unit could be modeled to track training and to reduce non-contact injuries. Finally, the interval time between the last injury and the new injury at the high-load is shorter than the low-load.

Polymerase chain reaction for Group B Streptococci (GBS) at labor highly correlates with vaginal GBS load

OBJECTIVE

To explore factors associated with a high vaginal GBS load during labor considering (1) the recto-vaginal GBS load at 35-37 weeks' gestation determined by culture and (2) the vaginal GBS colonization determined by a polymerase chain reaction (PCR) assay during labor.

METHODS

From an unselected cohort of 902 pregnant women, we obtained (1) recto-vaginal swabs for culture of GBS at 35-37 weeks' gestation (GBS_rectovag-36), (2) vaginal swabs for GBS PCR detection at labor (PCR_vag-labor), and (3) vaginal swabs for culture of GBS at labor (GBS_vag-labor). The GBS load was classified semi quantitatively according to a culture protocol without prior broth enrichment of the swab samples: none (0), few (+), some (++), or many (+++) GBS colonies.

RESULTS

Among 902 unselected pregnant women, 859 (95%) had a vaginal swab culture taken at labor, which was classified semi quantitatively. High load GBS_vag-labor (+++) were found in 31 participants. GBS_rectovag-36 showed a sensitivity of 90% (28/31) and a PPV of 23% (28/121), whereas PCR_vag-labor had a sensitivity of 98% (30/31, non-significant difference) and a PPV of 42% (30/71, p < .01). PCR at labor had a lower sensitivity (78%) for detection of vaginal colonization with GBS at labor (any load) compared to recto/vaginal colonization with GBS at 36 weeks (92%). Vaginal colonization with GBS at 36 weeks seemed to have a lower sensitivity for detecting GBS in vagina at labor for high load (48%) and for any load (39%).

CONCLUSION

PCR at labor has higher detection rate (non-significant) and PPV in identification of laboring women with a high load of vaginal GBS compared with recto-vaginal culture at 36 weeks' gestation.

Acute fatigue, and perceptual responses to resistance exercise

INTRODUCTION

Despite assumptions, there is an absence of research on acute fatigue responses to high- and low-load and advanced technique resistance exercise.

METHODS

Trained males (n = 8; age 27.2 ± 7.4 years, height 180.0 ± 6.6 cm, weight: 86.6 ± 10.3 kg) were assessed for decrement in maximal voluntary isometric torque (MVIT) and perceived effort and discomfort after heavier load (HL; 80% MVIT), lighter load (LL; 30% MVIT), forced repetition (FR), and breakdown set (BD) training protocols.

RESULTS

Analyses revealed a significant reduction in MVIT (P < 0.05) with a significant between-condition effect, and significant post-hoc pairwise comparisons between LL and both HL (P = 0.044) and FR (P = 0.013). There were no significant between-condition effects for effort or discomfort (P > 0.05).

DISCUSSION

Fatigue as a decrement in force production appears to follow a more complex relationship than simply 100% minus the force requirements of the task relative to a maximal voluntary contraction. Muscle Nerve 56: E141-E146, 2017.

Blood flow restriction increases metabolic stress but decreases muscle activation during high-load resistance exercise

INTRODUCTION

We investigated differences in metabolic stress (lactate) and muscle activation (electromyography; EMG) when high-load resistance exercise (HL) is compared with a condition in which blood flow restriction (BFR) is applied during the exercise or during the rest interval.

METHODS

Twelve participants performed HL with BFR during the intervals (BFR-I), during the set (BFR-S), and without BFR. Each condition consisted of 3 sets of 8 repetitions with knee extension at 70% of 1-repetition maximum. Lactate and root mean square (RMS) from the surface EMG of the vastus lateralis were calculated.

RESULTS

Lactate increased in all protocols but was higher with BFR-I than with BFR-S and HL. RMS decreased under all conditions, with a larger effect size in BFR-I (1.47) than in BFR-S (0.66) and HL (0.59).

DISCUSSION

BFR-I increases lactate, possibly as a result of reduced restoration of ATP. Muscle activation seems to be impacted by mechanical stress but may be reduced by metabolic stress. Muscle Nerve 57: 107-111, 2018.