Muscle Plasticity

T-cell-derived TNF-α and a cluster of immunological parameters from plasma allow a separation between SARS-CoV-2 convalescent versus vaccinated elite athletes

Guidelines for medical clearing after SARS-CoV-2 infection in elite athletes do not include T-cell immunity aspects despite its relevance in the course of COVID-19 disease. Therefore, we aimed to analyze T-cell-related cytokines before and after in-vitro activation of CD4⁺ T-cells. We sampled professional indoor sports athletes at medical clearing after SARS-CoV-2 infection obtaining clinical, fitness data, and serological data including CD4⁺ T-cell cytokines. All data were analyzed by principal component analysis and 2 × 2 repeated measures ANOVA. CD4⁺ T-cells were sampled for cell culture activation with anti-CD3/anti-CD28 tetramers. At medical clearing, CD4⁺ T-cells from convalescent athletes secreted increased levels of TNF-α 72 h after in-vitro activation compared to vaccinated athletes. IL-18 levels in plasma were elevated and a cluster of parameters differentiated convalescent from vaccinated athletes by 13 parameters at the timepoint of medical clearing. All clinical data indicate infection is resolved, while increased TNF-α may reflect altered proportions of peripheral T-cells as a hangover of infection.

Reporting of acute programme variables and exercise descriptors in rehabilitation strength training for tibiofemoral joint soft tissue injury: A systematic review

OBJECTIVE

Strength training acute programme variables (APVs) can impact tibiofemoral joint injury outcomes. Exercise descriptors (EDs; e.g. patient-position) specify configurations within which APVs are applied. Evidence-based practice depends on adequate reporting of APVs and EDs to replicate strength training interventions in clinical practice. This systematic review assessed APV and ED reporting for adults with tibiofemoral joint injury (anterior cruciate ligament (ACL)/posterior cruciate ligament (PCL)/medial collateral ligament (MCL)/lateral collateral ligament (LCL)/meniscus/hyaline cartilage (HC)).

METHODS

PRISMA guidelines were followed. Specific key-term combinations were employed and database searches performed. Descriptive/observational/experimental studies were included (2006-2018). Studies needed to report pre-defined APVs or EDs for ≥51% of all exercises to be included. Frequency counts were made of studies adequately reporting APVs and EDs.

RESULTS

Sixteen articles were included (ACL = 13; meniscus = 3). No PCL/MCL/LCL/HC articles were identified. Of nine APVs, five and four were consistently reported by the majority of ACL (≥7) and meniscal (≥2) studies, respectively. Of eight EDs, four were consistently reported by the majority of both ACL (≥8) and meniscal (≥2) studies.

CONCLUSION

Many APVs and EDs were not adequately reported. Future studies should better document APVs and EDs for higher standards of intervention reporting and enhanced translation of research to clinical practice.

Effect of expertise on pacing strategies and sprint performance in batsmen

OBJECTIVES

To assess whether the absence of a known endpoint, at the beginning of repeated-sprint bouts between the wickets, affects how skilled compared to less skilled batsmen pace themselves.

DESIGN

Repeated measures.

METHODS

Twelve skilled and 12 less skilled batsmen completed three trials. All trials required the same number of sprints (14 shuttles, 28 runs), while only the information before each trial differed. CT: batsmen were aware of the endpoint (28 runs). UT: not informed of the exercise endpoint and were required to run on command for an indefinite period (28 runs). DT: told they were only doing 14 runs when they actually did 28 runs. Sprint times, electrical muscle activity, and ratings of perceived effort were recorded.

RESULTS

Skilled batsmen were significantly faster than less skilled across all trials. Hamstring muscles activity decreased significantly over time in the skilled players during the UT, and during the CT and DT for the less skilled players. There were significant reductions in quadriceps muscles activation for the less skilled over time in all trials and in the skilled batsmen in the vastus medialis during the UT only. Perceived effort increased significantly in both groups in all trials. Skilled batsmen were fastest in the UT and less skilled fastest in the CT.

CONCLUSIONS

Better batting skill facilitated improved sprint times, especially when the exact endpoint was unknown. These results suggest that less skilled players should be given more central wicket practice with uncertainty to better develop their ability to maintain their sprint performance.

The impact of extended bed rest on the musculoskeletal system in the critical care environment

Prolonged immobility is harmful with rapid reductions in muscle mass, bone mineral density and impairment in other body systems evident within the first week of bed rest which is further exacerbated in individuals with critical illness. Our understanding of the aetiology and secondary consequences of prolonged immobilization in the critically ill is improving with recent and ongoing research to establish the cause, effect, and best treatment options. This review aims to describe the current literature on bed rest models for examining immobilization-induced changes in the musculoskeletal system and pathophysiology of immobilisation in critical illness including examination of intracellular signalling processes involved. Finally, the review examines the current barriers to early activity and mobilization and potential rehabilitation strategies, which are being, investigated which may reverse the effects of prolonged bed rest. Addressing the deleterious effects of immobilization is a major step in treatment and prevention of the public health issue, that is, critical illness survivorship.

The development, retention and decay rates of strength and power in elite rugby union, rugby league and American football: a systematic review

BACKGROUND AND AIM

Strength and power are crucial components to excelling in all contact sports; and understanding how a player's strength and power levels fluctuate in response to various resistance training loads is of great interest, as it will inevitably dictate the loading parameters throughout a competitive season. This is a systematic review of training, maintenance and detraining studies, focusing on the development, retention and decay rates of strength and power measures in elite rugby union, rugby league and American football players.

SEARCH STRATEGIES

A literature search using MEDLINE, EBSCO Host, Google Scholar, IngentaConnect, Ovid LWW, ProQuest Central, ScienceDirect Journals, SPORTDiscus and Wiley InterScience was conducted. References were also identified from other review articles and relevant textbooks. From 300 articles, 27 met the inclusion criteria and were retained for further analysis. STUDY QUALITY: Study quality was assessed via a modified 20-point scale created to evaluate research conducted in athletic-based training environments. The mean ± standard deviation (SD) quality rating of the included studies was 16.2 ± 1.9; the rating system revealed that the quality of future studies can be improved by randomly allocating subjects to training groups, providing greater description and detail of the interventions, and including control groups where possible.

DATA ANALYSIS

Percent change, effect size (ES = [Post-Xmean - Pre-Xmean)/Pre-SD) calculations and SDs were used to assess the magnitude and spread of strength and power changes in the included studies. The studies were grouped according to (1) mean intensity relative volume (IRV = sets × repetitions × intensity; (2) weekly training frequency per muscle group; and (3) detraining duration. IRV is the product of the number of sets, repetitions and intensity performed during a training set and session. The effects of weekly training frequencies were assessed by normalizing the percent change values to represent the weekly changes in strength and power. During the IRV analysis, the percent change values were normalized to represent the percent change per training session. The long-term periodized training effects (12, 24 and 48 months) on strength and power were also investigated.

RESULTS

Across the 27 studies (n = 1,015), 234 percent change and 230 ES calculations were performed. IRVs of 11-30 (i.e., 3-6 sets of 4-10 repetitions at 74-88% one-repetition maximum [1RM]) elicited strength and power increases of 0.42% and 0.07% per training session, respectively. The following weekly strength changes were observed for two, three and four training sessions per muscle region/week: 0.9%, 1.8 % and 1.3 %, respectively. Similarly, the weekly power changes for two, three and four training sessions per muscle group/week were 0.1%, 0.3% and 0.7 %, respectively. Mean decreases of 14.5% (ES = -0.64) and 0.4 (ES = -0.10) were observed in strength and power across mean detraining periods of 7.2 ± 5.8 and 7.6 ± 5.1 weeks, respectively. The long-term training studies found strength increases of 7.1 ± 1.0% (ES = 0.55), 8.5 ± 3.3% (ES = 0.81) and 12.5 ± 6.8% (ES = 1.39) over 12, 24 and 48 months, respectively; they also found power increases of 14.6% (ES = 1.30) and 12.2% (ES = 1.06) at 24 and 48 months.

CONCLUSION

Based on current findings, training frequencies of two to four resistance training sessions per muscle group/week can be prescribed to develop upper and lower body strength and power. IRVs ranging from 11 to 30 (i.e., 3-6 sets of 4-10 repetitions of 70-88% 1RM) can be prescribed in a periodized manner to retain power and develop strength in the upper and lower body. Strength levels can be maintained for up to 3 weeks of detraining, but decay rates will increase thereafter (i.e. 5-16 weeks). The effect of explosive-ballistic training and detraining on pure power development and decay in elite rugby and American football players remain inconclusive. The long-term effects of periodized resistance training programmes on strength and power seem to follow the law of diminishing returns, as training exposure increases beyond 12-24 months, adaptation rates are reduced.

Respiratory weakness in patients with chronic neck pain

Respiratory muscle strength is one parameter that is currently proposed to be affected in patients with chronic neck pain. This study was aimed at examining whether patients with chronic neck pain have reduced respiratory strength and with which neck pain problems their respiratory strength is associated. In this controlled cross-sectional study, 45 patients with chronic neck pain and 45 healthy well-matched controls were recruited. Respiratory muscle strength was assessed through maximal mouth pressures. The subjects were additionally assessed for their pain intensity and disability, neck muscle strength, endurance of deep neck flexors, neck range of movement, forward head posture and psychological states. Paired t-tests showed that patients with chronic neck pain have reduced Maximal Inspiratory (MIP) (r = 0.35) and Maximal Expiratory Pressures (MEP) (r = 0.39) (P < 0.05). Neck muscle strength (r > 0.5), kinesiophobia (r < -0.3) and catastrophizing (r < -0.3) were significantly associated with maximal mouth pressures (P < 0.05), whereas MEP was additionally negatively correlated with neck pain and disability (r < -0.3, P < 0.05). Neck muscle strength was the only predictor that remained as significant into the prediction models of MIP and MEP. It can be concluded that patients with chronic neck pain present weakness of their respiratory muscles. This weakness seems to be a result of the impaired global and local muscle system of neck pain patients, and psychological states also appear to have an additional contribution. Clinicians are advised to consider the respiratory system of patients with chronic neck pain during their usual assessment and appropriately address their treatment.

Changes in viscoelastic properties of skeletal muscles induced by subthalamic stimulation in patients with Parkinson's disease

BACKGROUND

Objective measurements would be useful to document the effect of deep brain stimulation in alleviating rigidity in patients with Parkinson's disease. The aim of the study was to examine the changes of viscoelastic properties in skeletal muscles as indicators of rigidity.

METHODS

Six patients in an advanced stage of Parkinson's disease participated in the study. The study took place in the off-medication conditions after one night of drug withdrawal. The wrist rigidity was examined according to the Unified Parkinson's Disease Rating Scale in both sides. Myotonometry (Myoton) was used to determine stiffness and elasticity in extensor digitorum muscles bilaterally. The measurements were repeated and compared during the stimulation-on and stimulation-off periods.

FINDINGS

A comparison of mean clinical motor scores revealed a significant improvement of parkinsonian symptoms due to brain stimulation. In particular, arm rigidity improved on average from 2.83 (1-4) in stimulation-off phase to 1.17 (0-2) in stimulation-on phase (P<0.05). The mean values of elasticity and stiffness were not significantly different in stimulation-on and stimulation-off conditions. The patients with elevated clinical rigidity scores had higher mean values of stiffness (262.5 vs 211.0; P<0.05) but the differences in elasticity were not significant.

INTERPRETATION

Increased rigidity is associated with increased values of viscoelastic stiffness. This paper supports the use of myotonometry for objective quantification of rigidity and in the future, this tool could prove helpful for optimizing deep brain stimulation settings in patients with Parkinson's disease.

Evaluation of viscoelastic parameters of the skeletal muscles in junior triathletes

Five male triathletes of the Estonian national junior team were observed during a seven-week competition period. The Myoton-2 equipment was used to describe the viscoelastic parameters of the skeletal muscles. The frequency of damped mechanical oscillation of the muscle tissue (Hz - indicating the tension in the muscle), logarithmic decrement of the oscillations (Theta - indicating the elasticity of the muscle) and stiffness (N m(-1)) of the muscle tissue were registered bilaterally in eight muscles in both the relaxed and the contracted states: BB - biceps brachii (caput longum); TB - triceps brachii (caput longum); BF - biceps femoris (caput longum); RF - rectus femoris; TA - tibialis anterior; GC - gastrocnemius (caput mediale); LD - latissimus dorsi; PM - pectoralis major (pars sternocostalis). A portable massage table was used for the subject to rest on during the measuring. For the measurement of the anterior muscles, the subject lay supine; for the posterior muscles the prone position was used. The (isometric) contraction was standardized simply by the same measuring position of the limb-the subject raised his arm or leg to an angle of 45 degrees from the horizontal level, using a 2.3 kg dumb-bell as an additional weight for the upper limb. The tarsal dorsiflexion and plantarflexion was performed against a fixed table to contract the crural muscles. The elasticity of the skeletal muscle is higher for the contracted state with respect to the relaxed one (p < 0.0001) and is described by decline of the value of logarithmic decrement, the stiffness and the tension in the muscle increases (p < 0.0001 for both parameters). The measured skeletal muscles differ significantly (p < 0.0018) by the viscoelastic properties in the relaxed state. In the relaxed state, TA was the most elastic (mean +/- SD; Theta-0.74 +/- 0.13), stiff (mean +/- SD; 346.68 +/- 60.34 N m(-1)) and tense muscle (mean +/- SD; 18.72 +/- 1.55 Hz). In the contracted state, the elasticity of TA did not change (0.76 +/- 0.14) while the stiffness and the tension in this muscle rose significantly (93% and 38%, accordingly). Personal differences (p < 0.005) exist if pooled data from the muscles are compared between the subjects.

Rehabilitation interventions for vegetative and minimally conscious patients

Brain injury rehabilitation is a complex and challenging task for all members of the multidisciplinary team. Medical advances have allowed more severely impaired patients to survive and consequently the number of patients in the vegetative and minimally conscious states have proportionately increased. Thus, the need for evidence-based practice and further research demonstrating the effects of specific rehabilitation interventions is required. This article reviews the current research and consensus on rehabilitation for patients in the vegetative and minimally conscious states.

O efeito de um programa de exercício físico aeróbio combinado com exercícios de resistência muscular localizada na melhora da circulação sistêmica e local: um estudo de caso

INTRODUÇÃO: A trombofilia, estado que predispõe à ocorrência de trombose, decorre da existência de alterações da hemostasia, podendo ser congênita ou adquirida. A deficiência de proteína S, que ocorre pela falta do co-fator para a proteína C, é uma alteração congênita que pode resultar em trombofilia. A reabilitação física, considerada uma terapêutica eficaz, tem seu papel definido na prevenção e tratamento de doenças cardiovasculares. OBJETIVO: Este estudo se propôs a verificar a influência do exercício físico aeróbio associado aos exercícios de resistência muscular localizada na circulação sistêmica e colateral do membro superior e inferior direito e na redução das conseqüências causadas pelas retrações decorrentes das cirurgias. MATERIAL E MÉTODO: A amostra foi composta por uma paciente do sexo feminino, 19 anos, portadora da síndrome de hipercoagulabilidade (trombofilia) congênita por deficiência da proteína S, com obstrução total na artéria axilar direita e parcial na artéria femoral superficial direita. O programa de exercícios foi dividido em duas fases. Fase I: Atividades para aumento da amplitude de movimentos, em que se realizavam aplicação de calor, alongamentos passivos manuais mantidos, drenagem linfática e manipulações Effleurage. Fase II: Constituída de exercício aeróbio (45 minutos de caminhada, três vezes por semana, intensidade de 60% a 85% da freqüência cardíaca máxima) e exercícios de resistência muscular localizada (contrações dinâmicas, três séries com o máximo de repetições possíveis, baixa intensidade, favorecendo fatores aeróbios). RESULTADOS: 1. Melhora da circulação colateral à artéria axilar, constatada pelo aumento na velocidade de pulso sistólico (verificado através do exame doppler pulsado) - na artéria radial, passou de 3,4cm/s para 16,8cm/s; na artéria braquial, de 8,7cm/s para 45,9cm/s. 2. Melhor tolerância ao exercício aeróbio. 3. Recuperação da capacidade funcional e amplitude de movimento do ombro. 4. Recuperação plena da autonomia para as atividades diárias. CONCLUSÕES: Os resultados obtidos demonstraram que a terapêutica adotada foi eficaz no tratamento dos transtornos provocados pela trombofilia.