Tendinous tissue properties after short and long-term functional overload: Differences between controls, 12 weeks and 4 years of resistance training

Aim - The potential for tendinous tissues to adapt to functional overload, especially after several years of exposure to heavy resistance training is largely unexplored. This study compared the morphological and mechanical characteristics of the patellar tendon and knee-extensor tendon-aponeurosis complex between young men exposed to long-term (4 years; n=16), short-term (12 weeks; n=15) and no (untrained controls; n=39) functional overload in the form of heavy resistance training. Methods - Patellar tendon cross-sectional area, vastus-lateralis aponeurosis area and quadriceps femoris volume, plus patellar tendon stiffness and Young's modulus, and tendon-aponeurosis complex stiffness, were quantified with MRI, dynamometry and ultrasonography. Results - As expected long-term trained had greater muscle strength and volume (+58% and +56% vs untrained, both P<0.001), as well as a greater aponeurosis area (+17% vs untrained, P<0.01), but tendon cross-sectional area (mean and regional) was not different between groups. Only long-term trained had reduced patellar tendon elongation/strain over the whole force/stress range, whilst both short-term and long-term overload groups had similarly greater stiffness/Young's modulus at high force/stress (short-term +25/22%, and long-term +17/23% vs untrained; all P<0.05). Tendon-aponeurosis complex stiffness was not different between groups (ANOVA, P = 0.149). Conclusion - Despite large differences in muscle strength and size, years of resistance training did not induce tendon hypertrophy. Both short-term and long-term overload, demonstrated similar increases in high force mechanical and material stiffness, but reduced elongation/strain over the whole force/stress range occurred only after years of overload, indicating a force/strain specific time-course to these adaptations

The influence of patellar tendon and muscle-tendon unit stiffness on quadriceps explosive strength in man

What is the central question of this study? \ud Do tendon and/or muscle–tendon unit stiffness influence rate of torque development? What is the main finding and its importance? In our experimental conditions, some measures of relative (to maximal voluntary torque and tissue length) muscle–tendon unit stiffness had small correlations with voluntary/evoked rate of torque development over matching torque increments. However, absolute and relative tendon stiffness were unrelated to voluntary and evoked rate of torque development. Therefore, the muscle aponeurosis but not free tendon influences the relative rate of torque development. Factors other than tissue stiffness more strongly determine the absolute rate of torque development. The influence of musculotendinous tissue stiffness on contractile rate of torque development (RTD) remains opaque. In this study, we examined the relationships between both patellar tendon (PT) and vastus lateralis muscle–tendon unit (MTU) stiffness and the voluntary and evoked knee-extension RTD. Fifty-two healthy untrained men completed duplicate laboratory sessions. Absolute and relative RTD were measured at 50 N m or 25% maximal voluntary torque (MVT) increments from onset and sequentially during explosive voluntary and evoked octet isometric contractions (supramaximal stimulation; eight pulses at 300 Hz). Isometric MVT was also assessed. Patellar tendon and MTU stiffness were derived from simultaneous force and ultrasound recordings of the PT and vastus lateralis aponeurosis during constant RTD ramp contractions. Absolute and relative (to MVT and resting tissue length) stiffness (k) was measured over identical torque increments as RTD. Pearson's correlations tested relationships between stiffness and RTD measurements over matching absolute/relative torque increments. Absolute and relative PT k were unrelated to equivalent voluntary/evoked (r = 0.020–0.255, P = 0.069–0.891). Absolute MTU k was unrelated to voluntary or evoked RTD (r ≤ 0.191, P ≥ 0.184), but some measures of relative MTU k were related to relative voluntary/evoked RTD (e.g. RTD for 25–50% MVT, r = 0.374/0.353, P = 0.007/0.014). In conclusion, relative MTU k explained a small proportion of the variance in relative voluntary and evoked RTD (both ≤19%), despite no association of absolute MTU k or absolute/relative PT k with equivalent RTD measures. Therefore, the muscle-aponeurosis component but not free tendon was associated with relative RTD, although it seems that an overriding influence of MVT negated any relationship of absolute MTU k and absolute RTD

Effective schools are Inclusive schools

This paper offers some insights into the ways in which networks of schools can work together in order to bring about school improvement. These activities are based on the Unesco teacher education strategies and the use of The Index for Inclusion (2002) as a vehicle for school inquiry purposes. These inquiries lead to a focus on classroom practice development and school policies and cultures that aim to reduce barriers to participation for all students. It focuses on key themes that have been seen as important in successful developments and more inclusive practices. It also offers 'school stories' illustrating how individual schools undertook their inquirie

Neural adaptations after 4 years vs. 12 weeks of resistance training vs. untrained

The purpose of this study was to compare the effect of resistance training (RT) duration, including years of exposure, on agonist and antagonist neuromuscular activation throughout the knee extension voluntary torque range. Fifty‐seven healthy men (untrained [UNT] n=29, short‐term RT [12WK] n=14, and long‐term RT [4YR] n=14) performed maximum and sub‐maximum (20‐80% maximum voluntary torque [MVT]) unilateral isometric knee extension contractions with torque, agonist and antagonist surface EMG recorded. Agonist EMG, including at MVT, was corrected for the confounding effects of adiposity (i.e. muscle‐electrode distance; measured with ultrasonography). Quadriceps maximum anatomical cross‐sectional area (QACSAMAX; via MRI) was also assessed. MVT was distinct for all three groups (4YR +60/+39% vs. UNT/12WK; 12WK +15% vs. UNT; 0.001<P≤0.021), and QACSAMAX was greater for 4YR (+50/+42% vs. UNT/12WK; [both] P<0.001). Agonist EMG at MVT was +44/+33% greater for 4YR/12WK ([both] P<0.001) vs. UNT; but did not differ between RT groups. The torque‐agonist EMG relationship of 4YR displayed a right/down shift with lower agonist EMG at the highest common torque (196 Nm) compared to 12WK and UNT (0.005≤P≤0.013; Effect size [ES] 0.90≤ES≤1.28). The torque‐antagonist EMG relationship displayed a lower slope with increasing RT duration (4YR<12WK<UNT; 0.001<P≤0.094; 0.56≤ES≤1.31), and antagonist EMG at the highest common torque was also lower for 4YR than UNT (‐69%; P<0.001; ES=1.18). In conclusion, 4YR and 12WK had similar agonist activation at MVT and this adaptation may be maximised during early months of RT. In contrast, inter‐muscular coordination, specifically antagonist co‐activation was progressively lower, and likely continues to adapt, with prolonged RT

Muscle size and strength : debunking the “completely separate phenomena” suggestion

This is a post-peer-review, pre-copyedit version of an article published in European Journal of Applied Physiology. The final authenticated version is available online at: http://dx.doi.org/10.1007/s00421-017-3616-

Training-specific functional, neural, and hypertrophic adaptations to explosive- vs. sustained-contraction strength training

Training specificity is considered important for strength training, although the functional and underpinning physiological adaptations to different types of training, including brief explosive contractions, are poorly understood. This study compared the effects of 12 wk of explosive-contraction (ECT, n = 13) vs. sustained-contraction (SCT, n = 16) strength training vs. control (n = 14) on the functional, neural, hypertrophic, and intrinsic contractile characteristics of healthy young men. Training involved 40 isometric knee extension repetitions (3 times/wk): contracting as fast and hard as possible for ∼1 s (ECT) or gradually increasing to 75% of maximum voluntary torque (MVT) before holding for 3 s (SCT). Torque and electromyography during maximum and explosive contractions, torque during evoked octet contractions, and total quadriceps muscle volume (QUADSVOL) were quantified pre and post training. MVT increased more after SCT than ECT [23 vs. 17%; effect size (ES) = 0.69], with similar increases in neural drive, but greater QUADSVOL changes after SCT (8.1 vs. 2.6%; ES = 0.74). ECT improved explosive torque at all time points (17-34%; 0.54 ≤ ES ≤ 0.76) because of increased neural drive (17-28%), whereas only late-phase explosive torque (150 ms, 12%; ES = 1.48) and corresponding neural drive (18%) increased after SCT. Changes in evoked torque indicated slowing of the contractile properties of the muscle-tendon unit after both training interventions. These results showed training-specific functional changes that appeared to be due to distinct neural and hypertrophic adaptations. ECT produced a wider range of functional adaptations than SCT, and given the lesser demands of ECT, this type of training provides a highly efficient means of increasing function

MDQC: a new quality assessment method for microarrays based on quality control reports

Motivation: The process of producing microarray data involves multiple steps, some of which may suffer from technical problems and seriously damage the quality of the data. Thus, it is essential to identify those arrays with low quality. This article addresses two questions: (1) how to assess the quality of a microarray dataset using the measures provided in quality control (QC) reports; (2) how to identify possible sources of the quality problems. Results: We propose a novel multivariate approach to evaluate the quality of an array that examines the ‘Mahalanobis distance' of its quality attributes from those of other arrays. Thus, we call it Mahalanobis Distance Quality Control (MDQC) and examine different approaches of this method. MDQC flags problematic arrays based on the idea of outlier detection, i.e. it flags those arrays whose quality attributes jointly depart from those of the bulk of the data. Using two case studies, we show that a multivariate analysis gives substantially richer information than analyzing each parameter of the QC report in isolation. Moreover, once the QC report is produced, our quality assessment method is computationally inexpensive and the results can be easily visualized and interpreted. Finally, we show that computing these distances on subsets of the quality measures in the report may increase the method's ability to detect unusual arrays and helps to identify possible reasons of the quality problems. Availability: The library to implement MDQC will soon be available from Bioconductor Contact: [email protected] Supplementary information: Supplementary data are available at Bioinformatics onlin

Assessing the Exposome with External Measures: Commentary on the State of the Science and Research Recommendations

The exposome comprises all environmental exposures that a person experiences from conception throughout the life course. Here we review the state of the science for assessing external exposures within the exposome. This article reviews (a) categories of exposures that can be assessed externally, (b) the current state of the science in external exposure assessment, (c) current tools available for external exposure assessment, and (d) priority research needs. We describe major scientific and technological advances that inform external assessment of the exposome, including geographic information systems; remote sensing; global positioning system and geolocation technologies; portable and personal sensing, including smartphone-based sensors and assessments; and self-reported questionnaire assessments, which increasingly rely on Internet-based platforms. We also discuss priority research needs related to methodological and technological improvement, data analysis and interpretation, data sharing, and other practical considerations, including improved assessment of exposure variability as well as exposure in multiple, critical life stages

Acute neuromuscular, kinetic, and kinematic responses to accentuated eccentric load resistance exercise

Neurological and morphological adaptations are responsible for the increases in strength that occur following the completion of resistance exercise training interventions. There are a number of benefits that can occur as a result of completing resistance exercise training interventions, these include: (i) reduced risk of developing metabolic health issues; (ii) decreased risk and incidence of falling; (iii) improved cardiovascular health; (iv) elevated mobility; (v) enhanced athletic performance; and (vi) injury prevention. Traditional resistance exercise (constant load resistance exercise (CL)) involves equally loaded eccentric and concentric phases, performed in an alternating manner. However, eccentric muscle actions have unique physiological characteristics, namely greater force production capacity and lower energy requirements, compared to concentric actions. These characteristics have led to the exploration of eccentric-focused resistance exercise for the purposes of injury prevention, rehabilitation, and enhancement of functional capacity. Accentuated eccentric load resistance exercise (AEL) is one form of eccentric-focused resistance exercise. This type of resistance exercise involves a heavier absolute external eccentric phase load than during the subsequent concentric portion of a repetition. Existing training study interventions comparing AEL to CL have demonstrated enhancements in concentric, eccentric, and isometric strength with AEL. However, no differences in strength adaptations have been reported in other AEL vs. CL training studies. Only 7 d intensified AEL training interventions have measured neuromuscular variables, providing evidence that enhanced neuromuscular adaptations may occur when AEL is compared to CL. Therefore, a lack of information is currently available regarding how AEL may differentially affect neuromuscular control when compared to CL. Furthermore, the equivocal findings regarding the efficacy of AEL make it difficult for exercise professionals to decide if they should employ AEL with their athletes or patients and during which training phase this type of resistance exercise could be implemented. Therefore, the aims of this thesis were: (i) to examine differences in acute neuromuscular, kinetic, and kinematic responses between AEL and CL during both lower-body single-joint resistance exercise and multiple-joint free weight resistance exercise; (ii) to assess acute force production and contractile characteristics following AEL and CL conditions; (iii) to investigate the influence of eccentric phase velocity (and time under tension) on acute force production and contractile characteristics following AEL and CL conditions; and (iv) to compare common drive and motor unit firing rate responses after single- and multiple-joint AEL and CL. Before investigating neuromuscular, kinetic, and kinematic responses to AEL it was deemed necessary to evaluate normalisation methods for a multiple-joint free weight resistance exercise that would permit the implementation of AEL. Therefore, the aim of the first study of the thesis was to evaluate voluntary maximal (dynamometer- and isometric squat-based) isometric and submaximal dynamic (60%, 70%, and 80% of three repetition maximum) electromyography (EMG) normalisation methods for the back squat resistance exercise. The absolute reliability (limits of agreement and coefficient of variation), relative reliability (intraclass correlation coefficient), and sensitivity of each method was assessed. Strength-trained males completed four testing sessions on separate days, the final three test days were used to evaluate the different normalisation methods. Overall, dynamic normalisation methods demonstrated better absolute reliability and sensitivity for reporting vastus lateralis and biceps femoris EMG compared to maximal isometric methods. Following the methodological study conducted in Chapter 2, the next study began to address the main aims of the thesis. The purpose of the third chapter of the thesis was to compare acute neuromuscular, kinetic, and kinematic responses between single-joint AEL and CL knee extension efforts that included two different eccentric phase velocities. Ten males who were completing recreational resistance exercise attended four experimental test day sessions where knee extension repetitions (AEL or CL) were performed at two different eccentric phase velocities (2 or 4 s). Elevated vastus lateralis eccentric neuromuscular activation was observed in both AEL conditions (p= 0.004, f= 5.73). No differences between conditions were detected for concentric neuromuscular or concentric kinematic variables during knee extension efforts. Similarly, no differences in after-intervention rate of torque development or contractile charactersitics were observed between conditions. To extend the findings of the third chapter of the thesis and provide mechanistic information regarding how AEL may differentially effect acute neuromuscular variables that have been reported to be undergo chronic adaptations, additional measures that were taken before and after the intervention described in the previous chapter were analysed. Therefore, the purpose of the fourth chapter of the thesis was to compare motor unit firing rate and common drive responses following single-joint AEL and CL knee extension efforts during a submaximal isometric knee extension trapezoid force trace effort. In addition, motor unit firing rate reliability during the before-intervention trapezoid force trace efforts was assessed. No differences in the maximum number of detected motor units were observed between conditions. A condition-time-point interaction effect (p= 0.025, f= 3.65) for firing rate in later-recruited motor units occurred, with a decrease in firing rate observed in after-intervention measures in the AEL condition that was completed with a shorter duration eccentric phase. However, no differences in common drive were detected from before- to after-intervention measures in any of the conditions. The time period toward the end of the plateau phase of before-intervention trapezoid force trace efforts displayed the greatest absolute and relative reliability and was therefore used for motor unit firing rate and common drive analysis. The purpose of the fifth chapter was to compare acute neuromuscular and kinetic responses between multiple-joint AEL and CL back squats. Strength-trained males completed two experimental test day sessions where back squat repetitions (AEL or CL) were performed. Neuromuscular and kinetic responses were measured during each condition. No differences in concentric neuromuscular or concentric kinetic variables during back squat repetitions were detected between conditions. Elevated eccentric phase neuromuscular activation was observed during the AEL compared to the CL condition in two to three of the four sets performed for the following lower-body muscles: (i) vastus lateralis (p< 0.001, f= 15.58); (ii) vastus medialis (p< 0.001, f= 10.77); (iii) biceps femoris (p= 0.003, f= 6.10); and (iv) gluteus maximus (p= 0.001, f= 7.98). There were no clear differences in terms of the neuromuscular activation contributions between muscles within AEL or CL conditions during eccentric or concentric muscle actions. Following the investigation of acute motor unit firing rate and common drive responses to lower limb single-joint AEL and CL in the fourth chapter of the thesis, the question arose as to whether or not similar responses would occur in a more complex model, such as a multiple-joint resistance exercise. Multiple-joint resistance exercise poses different neuromuscular activation, coordination, and stabilisation demands. Therefore, the purpose of the sixth chapter of the thesis was to compare acute motor unit firing rate and common drive responses following multiple-joint lower-body free weight AEL and CL. In addition, motor unit firing rate reliability during the before-intervention trapezoid force trace efforts, performed on a custom-built dynamometer, was assessed. No differences in motor unit firing rate or the number of motor units detected were observed between conditions. Condition-time-point interaction effects were observed for maximum peak cross-correlation coefficients (p= 0.028, f= 8.24), with a decrease from before to after intervention measures in the CL condition. However, differences in mean peak cross-correaltion coefficients and cross-correlation histogram distributions were not detected between conditions. As in Chapter 4 the time period toward the end of the plateau phase of before-intervention trapezoid force trace efforts displayed the greatest absolute reliability and was therefore used for motor unit firing rate and common drive analysis. Whereas, relative reliability was shown to be “poor” across all time phases. The results of the studies that comprise this thesis contribute new knowledge to the AEL research literature. In particular, the way that motor unit recruitment strategy responses were investigated following interventions provided new information regarding the acute neuromuscular effects of AEL and a new potential approach to investigating the hypothesised similarities between motor learning and resistance exercise. Previously, only transcranial magnetic stimulation had been used for this purpose. However, the contrasting motor unit firing rate and common drive response results of Chapter 4 and 6 of the thesis indicate further research is required to ascertain how acute measures quantified through the decomposition of surface EMG (such as motor unit firing rate and common drive) are related to chronic neuromuscualr adaptations following resistance exercise. The findings presented in the thesis also add to the existing body of AEL research literature by providing practitioners with novel data regarding the acute neuromuscular, kinetic, and kinematic responses during AEL. The results presented in Chapter 3 and 5 of the thesis suggest that AEL resistance exercise implemented in both single- and multiple-joint resistance exercise models presents no negative acute variable responses. Neither of the AEL models investigated acutely reduced concentric kinetic outputs, decreased neuromuscular contributions or activation from key agonist muscles during concentric or eccentric phases, or caused after-intervention lower-body force production or contractile characteristics to decline more than following CL. In addition, both AEL models involved greater eccentric phase knee extensor muscle contributions compared to CL. Therefore, given these findings exercise professionals who prescribe training interventions may want to consider the use of AEL depending on the characteristics and training goals of the individuals they work with. Despite these encouraging acute neuromuscular, kinetic, and kinematic responses to AEL further research is clearly required to confirm the efficacy of AEL on a longitudinal basis. Specifically, the efficacy of AEL for the concurrent enhancement of both chronic concentric and eccentric knee and hip extensor strength, eliciting chronic neuromuscular adaptations in these muscles, and preventing injury in a range of populations remains unclear

Marshall University Music Department Presents the Marshall University Symphonic Choir, 1968 Tour Concert

https://mds.marshall.edu/music_perf/1098/thumbnail.jp