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IgG4-related disease (IgG4-RD) is still an underestimated disorder which affects multiple organs, and its recognition as a distinct clinical disease has been only proved in the recent decades. The renal involvement has been documented in approximately 15% of patients with IgG4-RD, and the typical manifestation is a tubulo-interstitial nephritis. The main histological findings in IgG4-RD are typically a dense tissue infiltration of IgG4-positive plasma cells, storiform fibrosis, obliterative phlebitis, and frequently elevated IgG4 serum levels. Herein we report our atypical and peculiar clinical presentation of an IgG4-related nephropathy (IgG4-RN) and the remarkable response to rituximab (RTX) treatment at the renal imaging with computerized tomography assessment. The current nephrological evidences support the renal function recovery after steroids or steroids plus RTX therapy, even if the renal imaging data are not always shown. In a complex and enigmatic clinical scenario such as the IgG4-RN, both the renal biopsy and the renal imaging before and after the immunosuppressive therapy become mandatory tools to thoroughly define the diagnosis, the management and the response to the immunological therapy.

Background Microscopic nephrocalcinosis secondary to intratubular calcium phosphate (CaP) precipitation is thought to accelerate progression to end-stage renal failure in chronic kidney diseases. In phosphorus (P)-loaded uninephrectomized rats, intratubular CaP crystal formation and progressive tubular damage occurred when end-proximal tubule P concentration (ePTpc) increased above a threshold level. Methods We have calculated ePTpc in humans by urine P and creatinine concentration, with the end-proximal tubule fluid volume calculated either as lithium (Li) clearance (ePTpc-Li) or as a fixed 0.7 fraction of glomerular filtration rate (GFR), as published (ePTpc-70). Healthy people undergoing living transplant kidney donation before (DON-pre, n = 70) and after (DON-post, n = 64) nephrectomy and 25 patients with stage 2–5 CKD were investigated while on regular free diet. Results ePTpc showed a stepwise increase with decreasing functional renal mass (DON-pre 2.51 ± 0.99 and 1.56 ± 0.47 mg/dL for ePTpc-Li and -70 calculation, respectively; DON-post 3.43 ± 1.14 and 2.18 ± 0.44; CKD 5.68 ± 3.30 and 3.00 ± 1.30, P Conclusions ePTpc progressively increases in humans as functional renal mass falls independently from plasma P levels. Main determinants of ePTpc rise are GFR fall, degree of phosphaturia per unit GFR and P intake corrected for GFR. It may become a novel, potentially useful, indicator to guide management of CKD patients.

Background: Leishmaniasis is a neglected tropical disease and its cutaneous form manifests as ulcers or nodules, generally in exposed parts of the body. This work aimed to develop ivermectin (IVM) thermosensitive hydrogels as topical formulations to improve cutaneous leishmaniasis treatment. Materials & methods: Hydrogels based on poloxamers 407 and 188 with different concentrations of IVM were prepared and rheologically characterized. The IVM release profiles were obtained and mathematically analyzed using the Lumped model. Results: The formulation containing 1.5% w/w of IVM presented an adequate gelling temperature, an optimal complex viscosity and elastic modulus. Hydrogels allowed to modulate the release of IVM. Conclusion: IVM thermosensitive hydrogels can be considered a valuable alternative to improve the treatment of cutaneous leishmaniasis.

Background The risk of disease transmission from nonstandard risk donors (NSRDs) is low, and outcomes are similar or better relative to transplants performed with standard criteria donors. However, NSRDs have posed new ethical challenges to the informed consent (IC) process. Based on the shared decision-making model, coinciding with the 3 main timings of the IC process ([1] pretransplant assessments and waiting list registration, [2] time on the waiting list, and [3] time of the organ offer), we put forward a model (3-T Model) to summarize the knowledge on IC for NSRDs and to deliver conceptual and practical support to transplant providers on this emergent issue. Methods We searched PubMed and analyzed data from our area to provide evidence and ethical arguments to promote standardization of the timing of patient information, degree of patient participation, and disclosure of donor risk factors throughout the 3 stages of the time continuum leading to the potential acceptance of NSRDs. Results Each of the 3 timings carries special ethical significance and entails well-defined duties for transplant providers relative to patient involvement and information of the benefits and risks associated with NSRDs. Based on our framework, experience, and interpretation of the literature, we put forward a list of recommendations to combine standardization (ie, timing, content, and degree of patient participation) and individualization of IC. Conclusions The 3-T Model may enable the prevention of physicians' arbitrariness and the promotion of patient-centered care. Future studies will assess the effectiveness of the 3-T Model in transplant clinical practice.

Rocker-profile design shoes are commonly used in clinical settings. Such footwear reduces in-shoe pressure over the forefoot area during the gait, and depending on the rocker-profile type (i.e., toe-only, heel negative, or double rocker), affects lower limb kinematics, kinetics, and muscle electromyographic activity. However, whether wearing rocker-profile shoes influence the dynamics of the body centre of mass (BCoM) is unknown. We used a mathematical procedure combining Lissajous contours and Fourier analysis to describe the 3D trajectory of the BCoM in walking with rocker-profile (RollingSole) and flat (Control) shoes at 0.97, 1.25, and 1.53 m ssup-1/supin 30 participants. Harmonics amplitude and phase were compared using linear and circular statistics, respectively. External (Wsubext/sub), kinematic internal (Wsubint,k/sub) and total (Wsubtot/sub) mechanical works, and the mechanical energy fraction recovered from a pendular exchange of potential and kinetic energy were also calculated. RollingSole shoes yielded greater Wsubext/sub(1-9 %; P lt; 0.05) and fractional pendular energy exchange (1-8 %; P lt; 0.01), with lower Wsubint,k/sub(2-5 %; P lt; 0.05) and unchanged Wsubtot/sub(P ≥ 0.30). RollingSole shoes led also to a greater mean height of the BCoM (1-3 %; P lt; 0.01), and amplitude of the anteroposterior and vertical symmetric, and mediolateral 2nd-to-5th harmonics (1-30 %; P lt; 0.01). No differences between shoes were found for the harmonics phase (P ≥ 0.14). Our results indicate that RollingSole shoes enhanced an inverted pendulum-like behaviour of the BCoM during walking with no alterations in total mechanical work. This may result from the combination of rocker-profile design and greater BCoM height (through thicker soles) with such shoes, increasing recovery of mechanical energy in step-to-step transitions and mid-stance.

Biomechanics (and energetics) of human locomotion are generally studied at constant, linear, speed whereas less is known about running mechanics when velocity changes (because of accelerations, decelerations or changes of direction). The aim of this study was to calculate mechanical work and power and to estimate mechanical efficiency in shuttle runs (as an example of non-steady locomotion) executed at different speeds and over different distances. A motion capture system was utilised to record the movements of the body segments while 20 athletes performed shuttle runs (with a 180° change of direction) at three paces (slow, moderate and maximal) and over four distances (5, 10, 15 and 20 m). Based on these data the internal, external and total work of shuttle running were calculated as well as mechanical power; mechanical efficiency was then estimated based on values of energy cost reported in the literature. Total mechanical work was larger the faster the velocity and the shorter the distance covered (range: 2.3–3.7 J m−1 kg−1) whereas mechanical efficiency showed an opposite trend (range: 0.20–0.50). At maximal speed, over all distances, braking/negative power (about 21 W kg−1) was twice the positive power. Present results highlight that running humans can exert a larger negative than positive power, in agreement with the fundamental proprieties of skeletal muscles in vivo. A greater relative importance of the constant speed phase, associated to a better exploitation of the elastic energy saving mechanism, is likely responsible of the higher efficiency at the longer shuttle distances.

New findings What is the topic of this review? This narrative review explores past and recent findings on the mechanical determinants of energy cost during human locomotion, obtained by using a mechanical approach based on Konig's theorem (Fenn's approach). What advances does it highlight? Recent developments in analytical methods and of their applications allow a better understanding of the mechanical-bioenergetic interaction. Advances are: 1) the determination of "frictional" internal work; 2) the association between tendon work and apparent efficiency; 3) a better understanding of the role of energy recovery and internal work in pathological gait (amputees, stroke and obese); 4) a comprehensive analysis of human locomotion in (simulated) low gravity conditions. Abstract During locomotion, muscles use metabolic energy to produce mechanical work (in a more or less efficient way); as a matter of fact, energetics and mechanics can be considered as two sides of the same coin, the latter being investigated to understand the former. A mechanical approach based on Konig's theorem (Fenn's approach) has proved to be a useful tool to elucidate the determinants of the energy cost of locomotion (e. g. the pendulum-like model of walking and the bouncing model of running) and has resulted in many advances in this field. During the last 60 years, this approach has been refined and applied to explore the determinants of energy cost and efficiency in a variety of conditions (e.g. low gravity, un-steady speed). This narrative review aims to summarise current knowledge about the role that mechanical work has played in our understanding of energy cost to date, and to underline how recent developments in analytical methods and their applications in specific locomotion modalities (on a gradient, at low gravity and in un-steady conditions) and in pathological gaits (asymmetric gait pathologies, obese subjects and in the elderly) could continue to push this understanding further. The recent in vivo quantification of new aspects that should be included in the assessment of mechanical work (e.g. frictional internal work and elastic contribution) deserve future research and would improve our knowledge on the mechanical-bioenergetic interaction during human locomotion, as well as in sport science and space exploration. This article is protected by copyright. All rights reserved.

Purpose On level, the metabolic cost (C) of backward running is higher than forward running probably due to a lower elastic energy recoil. On positive gradient, the ability to store and release elastic energy is impaired in forward running. We studied running on level and on gradient to test the hypothesis that the higher metabolic cost and lower efficiency in backward than forward running was due to the impairment in the elastic energy utilisation. Methods Eight subjects ran forward and backward on a treadmill on level and on gradient (from 0 to + 25%, with 5% step). The mechanical work, computed from kinematic data, C and efficiency (the ratio between total mechanical work and C) were calculated in each condition. Results Backward running C was higher than forward running at each condition (on average + 35%) and increased linearly with gradient. Total mechanical work was higher in forward running only at the steepest gradients, thus efficiency was lower in backward running at each gradient. Conclusion Efficiency decreased by increasing gradient in both running modalities highlighting the impairment in the elastic contribution on positive gradient. The lower efficiency values calculated in backward running in all conditions pointed out that backward running was performed with an almost inelastic rebound; thus, muscles performed most of the mechanical work with a high metabolic cost. These new backward running C data permit, by applying the recently introduced ‘equivalent slope’ concept for running acceleration, to obtain the predictive equation of metabolic power during level backward running acceleration.

The aim of this study is to compare the histological results after socket preservation between dentin mixed with xenograft and dentin alone in tooth graft procedure. Six patients were included in this prospective case series study and treated in three clinical centers using standardized clinical procedures. This clinical trial enrolled patients with three walls post-extractive defects requiring the restoration of bone dimension and shape in mandibular zone. The patients were divided in two groups: extracted teeth alone (first group) and extracted teeth mixed with equal quantity of xenograft (second group). The extracted tooth was cleaned and processed by a recently introduced automated device, that allows fragmentation and partial demineralization of the tooth matrix and used as graft material. The graft obtained in this way, was inserted at the time of the extraction. A covering membrane was used to protect the graft. Implants were placed after 4 months of healing. Bone biopsies of the all grafted sites were taken at the time of implant surgery, for histological analysis. Descriptive statistics was used to synthesize the results, using mean values and standard deviations. Six patients (5 women, mean age at surgery 50.3±12.1 years) were treated and after 4 months of healing both groups, grafts height appeared stable. No signs of infection were present. Bone biopsy were taken in all grafted sites (3 with group one and 3 with group two). The histologic analysis revealed no inflammatory or infective reaction against both groups. The histomorphometry results between the two groups are different. The first group show an amount of new bone greater than the second group (+85.29%) and minor quantity of residual graft (-83.59%). The dentin alone shows a larger amount of new bone.

The impact of cancer on death of elderly kidney transplant recipients has been extensively investigated, but with conflicting results. Unlike their younger counterparts, in elderly kidney transplant recipients cardiovascular and infectious disease may outweigh cancer in causing the patient’s death. Using competing risk analysis on a large retrospective cohort of kidney transplant recipients, we estimated the cause-specific cumulative incidence and hazard of death in different age categories and calculated standardized mortality ratios (SMRs) to compare mortality rates with the general population. Six thousand seven hundred eighty-nine kidney transplant recipients were followed-up for a median of 9 years. Ten years after transplantation, in transplant recipients aged 20–39, 40–59, and 60+, the cumulative incidence of cancer-related death was 0.6 (95% confidence interval [CI]: 0.3–1.0), 2.9 (2.3–3.6) and 5.3% (3.5–7.5), whereas the SMR was 9.1 (5.5–15.0), 2.0 (1.6–2.5), and 0.8 (0.6–1.0), respectively. At variance with young recipients, the hazard and the cumulative incidence of cardiovascular-related death in elderly recipients was well above that of cancer-related death. Relative to the general population, cancer-related death is increased in young but not in elderly kidney transplant recipients because of the more marked increased incidence of competing cause of death in the latter category.

The clinical characteristics, management, and outcome of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) after solid organ transplant (SOT) remain unknown. We report our preliminary experience with 18 SOT (kidney [44.4%], liver [33.3%], and heart [22.2%]) recipients diagnosed with COVID-19 by March 23, 2020 at a tertiary-care center at Madrid. Median age at diagnosis was 71.0 ± 12.8 years, and the median interval since transplantation was 9.3 years. Fever (83.3%) and radiographic abnormalities in form of unilateral or bilateral/multifocal consolidations (72.2%) were the most common presentations. Lopinavir/ritonavir (usually associated with hydroxychloroquine) was used in 50.0% of patients and had to be prematurely discontinued in 2 of them. Other antiviral regimens included hydroxychloroquine monotherapy (27.8%) and interferon-β (16.7%). As of April 4, the case-fatality rate was 27.8% (5/18). After a median follow-up of 18 days from symptom onset, 30.8% (4/13) of survivors developed progressive respiratory failure, 7.7% (1/13) showed stable clinical condition or improvement, and 61.5% (8/13) had been discharged home. C-reactive protein levels at various points were significantly higher among recipients who experienced unfavorable outcome. In conclusion, this frontline report suggests that SARS-CoV-2 infection has a severe course in SOT recipients.

The aim of this paper is to investigate the mechanical and metabolic reasons of the spontaneous gait/speed choice of ascending short flight of stairs, where walking on every step or running on every other step are frequently interchangeable options. Twenty-four subjects' kinematics, oxygen uptake (V̇O2), ventilation and heart rate were sampled during climbing one and two flights of stairs while using the two gaits. Although motor acts were very short in time (5-22 s), metabolic kinetics, extending in the successive 250 s after the end of climbing, consistently reflected the (equivalent of the) needed mechanical energy and allowed to compare the two ascent choices: despite a 250% higher mechanical power associated to running, measured V̇O2, ventilation and heart rate peaked only at +25% with respect to walking, and in both gaits at a much lower values than V̇O2max despite of predictions based on previous gradient locomotion studies. Mechanical work and metabolic cost of transport, as expected, showed similar increase (+25%) in running. For stairs up to 4.8 m tall (30 steps at 53% gradient), running makes us consuming slightly more calories than walking, and in both gaits at no discomfort at all. The cardio-respiratory-metabolic responses similarly delay and damp the replenishing of phosphocreatine stores, which were much faster depleted during the impulsive, highly powered mechanical event, with almost overlapping time courses. Such a discrepancy between mechanical and metabolic dynamics allows to afford almost-to-very anaerobic climbs and to interchangeably decide whether to walk or run up a short flight of stairs.

Sprint running is a common feature of many sport activities. The ability of an athlete to cover a distance in the shortest time relies on his/her power production. The aim of this study was to provide an exhaustive description of the mechanical determinants of power output in sprint running acceleration and to check whether a predictive equation for internal power designed for steady locomotion is applicable to sprint running acceleration. Eighteen subjects performed two 20 m sprints in a gym. A 35-camera motion capture system recorded the 3D motion of the body segments and the body center of mass (BCoM) trajectory was computed. The mechanical power to accelerate and rise BCoM (external power, Pext ) and to accelerate the segments with respect to BCoM (internal power, Pint ) was calculated. In a 20 m sprint, the power to accelerate the body forward accounts for 50% of total power; Pint accounts for 41% and the power to rise BCoM accounts for 9% of total power. All the components of total mechanical power increase linearly with mean sprint velocity. A published equation for Pint prediction in steady locomotion has been adapted (the compound factor q accounting for the limbs' inertia decreases as a function of the distance within the sprint, differently from steady locomotion) and is still able to predict experimental Pint in a 20 m sprint with a bias of 0.70 ± 0.93 W kg-1 . This equation can be used to include Pint also in other methods that estimate external horizontal power only.

Background: Although optimization of immunosuppressive schemes in renal transplantation have minimized acute posttransplant complications, long-term outcomes are still not optimal and most of the chronic graft damage is drug-related. Therefore, to define the best long-term maintenance immunosuppressive regimen is of major importance in renal transplantation. To assess this objective, we undertook a large, multicenter cohort study in Italy. Methods: We retrospectively analyzed data of 5635 patients (enrolled from 1983 to 2012) and we assessed the impact of 3 major immunosuppressive regimens (calcineurin inhibitors+antimetabolites+corticosteroids [CNI+ANT+CS] vs CNI+mammalian target-of-rapamycin (mTOR) inhibitors+CS [CNI+mTOR-I+CS] vs CNI+CS) on long-term clinical outcomes by employing several statistical algorithms. Results: The overall difference in the incidence of outcome over time was not statistically different within the first 5 years of follow-up (P =.13); however, it became significant at 10 years and 20 years (P

Background The risk of wound healing complications (WHCs) and the early use of mammalian target of rapamycin inhibitors after kidney transplantation (KT) have not been fully addressed. Methods The NEVERWOUND study is a 3-month, multicenter, randomized, open-label study designed to evaluate whether a delayed (ie, 28 ± 4 d posttransplant) immunosuppression regimen based on everolimus (EVR) reduces the risk of WHC versus EVR started immediately after KT. Secondary endpoints were treatment failure (biopsy-proven acute rejection, graft loss, or death), delayed graft function, patient and graft survival rates, and renal function. Results Overall, 394 KT recipients were randomized to receive immediate (N = 197) or delayed (N = 197) EVR after KT. At 3 months, WHC-free rates in the immediate EVR versus delayed EVR arm, considering the worst- and best-case scenario approach, were 0.68 (95% confidence interval [CI], 0.62-0.75) versus 0.62 (95% CI, 0.55-0.68) (log-rank P = 0.56) and 0.70 (95% CI, 0.64-0.77) versus 0.72 (95% CI, 0.65-0.78) (log-rank P = 0.77), respectively. The 3- and 12-month treatment failure rates, delayed graft function and renal function, and patient and graft survival were not different between the arms. Conclusions The early introduction of EVR after KT did not increase the risk of WHC, showing good efficacy and safety profile.

Controlled experimental protocols for metabolic cost assessment of speed-changing locomotion are quite complex to design and manage. The use of the ‘equivalent slope’, i.e. the gradient locomotion at constant speed metabolically equivalent to a level progression in acceleration, has proved valuable in the estimation of the metabolic cost of speed-changing gaits. However, its use with steep slopes requires extrapolation of the experimental cost versus gradient function for constant running speed, resulting in less-reliable estimates. The present study extended the model to also work with deceleration, and revised the predictive equation to enable it to be applied to much higher levels of speed change. Shuttle running at different distances (from 5+5 to 20+20 m) was then investigated using the novel approach and software, and the predictions in terms of metabolic cost and efficiency compare well with the experimental data.

A model to predict the mechanical internal work of breaststroke swimming was designed. It allowed us to explore the frequency-internal work relationship in aquatic locomotion. Its accuracy was checked against internal work values calculated from kinematic sequences of eight participants swimming at three different self-chosen paces. Model predictions closely matched experimental data (0.58 ± 0.07 vs 0.59 ± 0.05 J kg(-1)m(-1); t(23)=-0.30, P=0.77), which was reflected in a slope of the major axis regression between measured and predicted total internal work whose 95% confidence intervals included the value of 1 (β=0.84, [0.61, 1.07], N=24). The model shed light on swimmers ability to moderate the increase in internal work at high stroke frequencies. This strategy of energy minimization has never been observed before in humans, but is present in quadrupedal and octopedal animal locomotion. This was achieved through a reduced angular excursion of the heaviest segments (7.2 ± 2.9° and 3.6 ± 1.5° for the thighs and trunk, respectively, P

Hypogravity challenges bipedal locomotion in its common forms. However, as previously theoretically and empirically suggested, humans can rely on “skipping,” a less common gait available as a functional analog (perhaps a vestigium) of quadrupedal gallop, to confidently move when gravity is much lower than on Earth. We set up a 17-m-tall cavaedium (skylight shaft) with a bungee rubber body-suspension system and a treadmill to investigate the metabolic cost and the biomechanics of low-gravity (Mars, Moon) locomotion. Although skipping is never more metabolically economical than running, the difference becomes marginal at lunar gravities, with both bouncing gaits approaching values of walking on Earth (cost ≈2 J·kg−1·m−1). Nonmetabolic factors may thus be allowed to dominate the choice of skipping on the Moon. On the basis of center of pressure measurements and body segments kinetics, we can speculate that these factors may include a further reduction of mechanical work to move the limbs when wearing space suits and a more effective motor control during the ground (regoliths)-boot interaction.

Background Previous research has shown that use of a dynamic-response prosthetic foot (DRF) that incorporates a small passive hydraulic ankle device (hyA-F), provides certain biomechanical benefits over using a DRF that has no ankle mechanism (rigA-F). This study investigated whether use of a hyA-F in unilateral trans-tibial amputees (UTA) additionally provides metabolic energy expenditure savings and increases the symmetry in walking kinematics, compared to rigA-F. Methods Nine active UTA completed treadmill walking trials at zero gradient (at 0.8, 1.0, 1.2, 1.4, and 1.6 of customary walking speed) and for customary walking speed only, at two angles of decline (5° and 10°). The metabolic cost of locomotion was determined using respirometry. To gain insights into the source of any metabolic savings, 3D motion capture was used to determine segment kinematics, allowing body centre of mass dynamics (BCoM), differences in inter-limb symmetry and potential for energy recovery through pendulum-like motion to be quantified for each foot type. Results During both level and decline walking, use of a hyA-F compared to rigA-F significantly reduced the total mechanical work and increased the interchange between the mechanical energies of the BCoM (recovery index), leading to a significant reduction in the metabolic energy cost of locomotion, and hence an associated increase in locomotor efficiency (p

Understanding the biomechanics of Alpine skiing is fundamental to the design of training protocols, to identify the metabolic burden of athletes and to help preventing traumas. Despite the apparent simplicity of the overall mechanics related to a descent with skiis, the scientific community is still uncertain about the role of muscle contraction in controlling the trajectory on the snow and about the partitioning between force and skill in determining the performance outcome. Generally speaking, skiers increase their body energy (in terms of potential energy) by taking the cable car up to the mountain top; then, to reach the bottom of the track, all that energy needs to be dissipated (as heat). There are just three dissipators involved: snow, air and muscles. If muscles play a major role in transforming potential energy into heat, they need to contract eccentrically, and athletes should be mostly trained in that respect. Conversely, if snow (and its displacement) is responsible for most of the slowdown of the skier, it would be advisable for racers to be trained to generate force both concentrically and eccentrically, with a deeper focus on controlling the fast and intense alternation of the two muscle conditions (a sort of ‘intensively perturbed isometric contraction’). This chapter starts from constraints from physics and, through experimental data, tries to shed light on this, still debated topic.

The use of poles during Nordic Walking (NW) actively engages the upper body to propel the body forward during walking. Evidence suggests that NW leads to a longer stride and higher speed, and sometimes to increased ground reaction forces with respect to conventional walking (W). The aim of this study was to investigate if NW is associated with different changes in body centre of mass (COM) motion and limbs energy patterns, mechanical work and efficiency compared to W. Eight experienced Nordic Walkers performed 5-min W and NW trials on a treadmill at 4kmh-1. Steady state oxygen consumption and movements of body segments and poles were measured during each trial. We found greater fluctuation of kinetic (KE) and potential (PE) energy associated with COM displacement for NW compared to W. An earlier increase of KE for NW than for W, probably due to the propulsive action of poles, modified the synchronization between PE and KE oscillations so that a 10.9% higher pendular recovery between these energies was found in NW. The 10.2% higher total mechanical work found for NW was mainly due to the greater work required to move upper limbs and poles. NW was 20% less efficient and was metabolically more demanding than W, this difference could be ascribed to isometric contraction and low efficiency of upper musculature. Concluding, NW can be considered a highly dynamic gait, with distinctive mechanical features compared to conventional gait, due to pole propulsion and arm/pole swing.

Comment on: "How Biomechanical Improvements in Running Economy Could Break the 2-Hour Marathon Barrier''

Recumbent bicycles (RB) are high performance, human-powered vehicles. In comparison to normal/upright bicycles (NB) the RB may allow individuals to reach higher speeds due to aerodynamic advantages. The purpose of this investigation was to compare the non-aerodynamic factors that may potentially influence the performance of the two bicycles. 3D body centre of mass (BCoM) trajectory, its symmetries, and the components of the total mechanical work necessary to sustain cycling were assessed through 3D kinematics and computer simulations. Data collected at 50, 70, 90 110 rpm during stationary cycling were used to drive musculoskeletal modelling simulation and estimate muscle-tendon length. Results demonstrated that BCoM trajectory, confined in a 15-mm side cube, changed its orientation, maintaining a similar pattern across all cadences in both bicycles. RB displayed a reduced additional mechanical external power (16.1 ± 9.7 W on RB vs. 20.3 ± 8.8 W on NB), a greater symmetry on the progression axis, and no differences in the internal mechanical power compared to NB. Simulated muscle activity revealed small significant differences for only selected muscles. On the RB, quadriceps and gluteus demonstrated greater shortening, while biceps femoris, iliacus, and psoas exhibited greater stretch; however, aerodynamics still remains the principal benefit.

Most of the inverse modelling of body dynamics in sports assumes that every segment is ‘rigid’ and moves ‘as a whole’, although we know that uncontrolled wobbling masses exist and in specific condition their motion should be optimised, both in engineering and biology. The visceral mass movement within the trunk segment potentially interferes with respiration and motion acts such as locomotion or jumping. The aim of this paper is to refine and expand a previously published methodology to estimate that relative motion by testing its ability to detect the reduced vertical viscera excursion within the trunk. In fact, a respiratory-assisted jumping strategy is expected to limit viscera motion stiffening the abdominal content of the bouncing body. Six subjects were analysed, by using inverse dynamics incorporating wobbling masses, during repeated vertical jumps performed before and after a specific respiratory training period. The viscera excursion, which showed consistent intra-individual time courses, decreased by about 30% when the subjects had become familiarized with the trunk-stiffening maneuver. We conclude that: (1) present methodology proved to detect subtle visceral mass mass movement within the trunk during repetitive motor acts and, particularly, (2) a newly proposed respiratory maneuver/training devoted to stiffening the trunk segment can reduce viscera vertical displacement.

This review aims to provide both researchers and coaches with a comprehensive overview of race walking biomechanics and to point out new viable route for future analyses. The examined literature has been divided into three categories according to the method of analysis: kinematics, ground reaction forces and joint power/efficiency. From an overall view, race walking athletes seem to adhere to the 'straightened knee' rule, but at race speed they do not observe the 'no-flight time' rule. The coach-oriented analysis highlights that stride length (SL) is more important than stride frequency (SF) for increasing speed and it is mainly obtained by ankle and hip joint power. Moreover, kinematic differences (SF, SL and flight time) between male and female athletes were shown. Also, we found that the maximal speed prediction according to dynamic similarity theory with walking (Froude number) is not applicable as the 3D trajectory of the body centre of mass does not follow an arc of circumference as in walking. The analysed literature shows some shortcomings: (1) the data collection is often unreliable because of the mixture of gender and performance level and (2) the analysis has sometimes been performed on a limited number of strides and speeds. These limitations lead to a scattered and incomplete gait description and a biased application of the results. The research strategy adopted so far is promising but further rigorous analyses need to be approached to obtain a fully comprehensive picture of race walking and to provide coaches with consistent results and reference values.

Overuse injuries are predominant in sports involving the repetition of similar movements patterns, such as in volleyball or beach volleyball, and they may represent as much a problem as do acute injuries. This review discusses the prevalence of two of the most common overuse-related injuries in volleyball: shoulder and back/spine injuries. Risk factors and the aetiology of these injuries are illustrated in order to make possible to initiate preventive programme or post-injuries solutions. Data collected from literature showed a moderately higher injury rate for overuse shoulder injuries compared to the back/spine (19.0 ± 11.2% and 16.8 ± 9.7%, respectively). These data could be underestimated, and future epidemiological studies should consider overuse injuries separately from the others, with new methodological approaches. In addition to age, biomechanical and anatomical features of a volleyball technique utilised in game and the amount of hours played are considered as the main risk factors for overuse upper limb injuries, both for professional and recreational athletes. Together with post-injuries solutions, great importance has to be placed on preventive programmes, such as preventive rehabilitation, stretching, adequate warm up, strength-power exercises, etc. Furthermore, it is particularly suggested that coaches and players work together in order to develop new game/training techniques that minimise stresses and range of motion of the principal anatomical structures involved, while maintaining athletes performance.

Carrying heavy loads in the Himalayan region is a real challenge. Porters face extreme ranges in terrain condition, path steepness, altitude hypoxia and climate for 6–8 h a day, many months a year, since they were boys. It has been previously shown that, when carrying loads on level terrain, porters' metabolic economy is higher than in Caucasians but the reasons are still unknown. We monitored Nepalese porters both during 90 km trekking in Khumbu Valley and at two different altitudes (3490 and 5050 m above sea-level), where they were compared to Caucasian mountaineers during (22%) gradient walking. Both subject groups carried a load of up to 90% body mass. The remarkably higher performance of porters during uphill locomotion (+60% in speed, +39% mechanical power) is only partly explained by the lower cost of loaded walking (−20%), being also the result of a better cardio-circulatory adaptation to altitude, which generates a higher mass-specific metabolic power (+30%). Consequently, Nepalese porters show higher efficiency, both during uphill and downhill loaded walking. Their higher economy on steep paths cannot be ascribed to a better exchange between potential and kinetic energy, as in our experiments the body centre of mass travelled monotonically uphill (or downhill). A different oscillation pattern of the loaded head–trunk segment, together with the analysis of the different components of the mechanical work during load carrying, suggests that achieved motor skills in balancing the loaded body segment above the hip could play a role in determining the better economy of porters.

Acceleration and deceleration phases characterise shuttle running (SR) compared to constant speed running (CR); mechanical work is thus expected to be larger in the former compared to the latter, at the same average speed (v mean). The aim of this study was to measure total mechanical work (W tot + , J kg−1 m−1) during SR as the sum of internal (W int + ) and external (W ext + ) work and to calculate the efficiency of SR. Twenty males were requested to perform shuttle runs over a distance of 5 + 5 m at different speeds (slow, moderate and fast) to record kinematic data. Metabolic data were also recorded (at fast speed only) to calculate energy cost (C, J kg−1 m−1) and mechanical efficiency (eff+ = W tot + C −1) of SR. Work parameters significantly increased with speed (P

In Medieval Europe, soldiers wore steel plate armour for protection during warfare. Armour design reflected a trade-off between protection and mobility it offered the wearer. By the fifteenth century, a typical suit of field armour weighed between 30 and 50 kg and was distributed over the entire body. How much wearing armour affected Medieval soldiers' locomotor energetics and biomechanics is unknown. We investigated the mechanics and the energetic cost of locomotion in armour, and determined the effects on physical performance. We found that the net cost of locomotion (Cmet) during armoured walking and running is much more energetically expensive than unloaded locomotion.Cmetfor locomotion in armour was 2.1–2.3 times higher for walking, and 1.9 times higher for running when compared withCmetfor unloaded locomotion at the same speed. An important component of the increased energy use results from the extra force that must be generated to support the additional mass. However, the energetic cost of locomotion in armour was also much higher than equivalent trunk loading. This additional cost is mostly explained by the increased energy required to swing the limbs and impaired breathing. Our findings can predict age-associated decline in Medieval soldiers' physical performance, and have potential implications in understanding the outcomes of past European military battles.