From “sliding” to “winding” filaments theory: A narrative review of mechanisms behind skeletal muscle contraction

The physiological mechanisms behind muscle contraction are a main concept in sport medicine and rehabilitation. The sarcomere is the functional unit of skeletal muscle and several proteins definite its complex structure. The most common theory to explain muscle contraction was proposed in the last 50’s and has become widely popular and accepted: the “sliding filaments” theory. Even if this hypothesis was able to justify some form of muscle contraction, other processes are not fully described by it. Eccentric contraction and some phenomena, like the “force enhancement during stretch” concept described in the 2002, are not explicable according to the sliding filament theory. Therefore, several hypotheses have been suggested over the years, such as the “popping sarcomeres” theory and the “winding filament” theory. Some other proteins, like titin, have gained a main role in the physiology of the sarcomere and should be relevant to explain mechanisms of eccentric contraction, where the sarcomere generates highest level of tension while it is lengthening. The aim of this review is to summarize the physiological theories of muscle contraction and to define concepts applicable in sport medicine and in rehabilitation areas

Tendinopathies of the hip and pelvis in athletes: A narrative review

Tendon disorders represent some of the most frequent musculoskeletal complaints worldwide. In the athletic population, tendinopathy could affect different anatomical districts. Tendons surrounding hip and pelvis are frequently involved due to overuse and high functional demands in the athletes. These disorders negatively impact on sport performance, since they are a long-lasting clinical condition requiring a multimodal management. Great trochanter pain syndrome, proximal hamstring tendinopathy, insertional adductor tendinopathy and ileopsoas tendinopathy are the most common clinical conditions involving tendon structures of the hip and pelvis. Due to the anatomical complexity of the region, the relationship with pelvic organs, the demographic and anthropometric characteristics of the athletes, the differential diagnosis between these musculoskeletal disorders and other diseases is often difficult to conduct and some therapeutic options are challenging. Modification of risk factors, changes in training protocols, some specific therapeutic exercise programs and rehabilitation procedures have been proposed as an efficient conservative management strategy, guarantying a complete recovery of athletic function. Surgical approaches are required in a specific subset of patients. This narrative literature review aims to summarize current understanding and areas of ongoing research about the clinical features, diagnostic keys and therapeutic options of the main clinical tendinopathies surrounding hip and pelvis

The effects of beta (2)-adrenergic receptors activation on the cardiovascular system and on the skeletal muscle: A narrative review

Beta(2)-adrenergic receptors (adrenoceptors) are activated by the catecholamines norepinephrine and epinephrine. Adrenoceptors are found in different tissues, such as smooth muscle, skeletal muscle and myocardium. Stimulation of adrenoceptors is implicated in several physiological functions in the body, such as bronchodilation, increased perfusion and vasodilation. The latters, together with increased muscular mass and contraction speed, facilitate muscle’s motility and contraction. In the cardiovascular system, the activation of adrenoceptors increases heart muscle contraction, cardiac output and heart rate. Some studies also suggested a cardioprotective role of the stimulation of adrenoceptors. Beta(2)-adrenergic receptors agonists, principally divided in long-acting beta(2) agonists (LABAs) and short-acting beta(2) agonists (SABAs), are primarily used to treat asthma and other pulmonary disorders. Beta(2)-adrenergic receptors activation has been correlated with anabolic properties and muscular hypertrophy with the use of oral clenbuterol, as well as intravenous albuterol. Given these anabolic, lipolytic and performance-enhancing effects, LABAs are frequently abused by athletes. For this reason, most of these drugs are banned by the World Anti-Doping Agency, or admissible only with limitations. The aim of this narrative review is to report the results of some recent studies about the effects of beta(2)-adrenergic receptors activation on the cardiovascular system and on the skeletal muscle

Achilles tendon pathologies: How to choose the best treatment

The Achilles tendon is the thickest and strongest tendon of the human body and it gets frequently injured during sports activity. The incidence of Achilles tendon pathologies has increased over the last decades, especially in the last few years, as a result of the increased sports participation among general population and for the diffusion of competitive sports at a high level. Although the increased interest and number of studies about Achilles tendon pathologies, at the moment there is not a consensual point of view on which is the best treatment for Achilles tendon injuries, and its management is still controversial. Treatment options mainly include conservative treatment and surgical repair. The decision for treatment in patients with an Achilles tendon pathology should be tailored on patient’s needs and level of activity, since patients with high activity levels may accept the risk of a higher complication rate to rapidly return to previous activity, while less active patients or those who cannot undergo surgery due to comorbidities may choose the non-operative option to decrease the risk of infection and other complications. The aim of this article is to give an insight about the most used and recent treatment options for Achilles tendon pathologies

Achilles tendon pathologies: How to choose the best treatment

The Achilles tendon is the thickest and strongest tendon of the human body and it gets frequently injured during sports activity. The incidence of Achilles tendon pathologies has increased over the last decades, especially in the last few years, as a result of the increased sports participation among general population and for the diffusion of competitive sports at a high level. Although the increased interest and number of studies about Achilles tendon pathologies, at the moment there is not a consensual point of view on which is the best treatment for Achilles tendon injuries, and its management is still controversial. Treatment options mainly include conservative treatment and surgical repair. The decision for treatment in patients with an Achilles tendon pathology should be tailored on patient’s needs and level of activity, since patients with high activity levels may accept the risk of a higher complication rate to rapidly return to previous activity, while less active patients or those who cannot undergo surgery due to comorbidities may choose the non-operative option to decrease the risk of infection and other complications. The aim of this article is to give an insight about the most used and recent treatment options for Achilles tendon pathologies

Selected components of physical fitness in rhythmic and artistic youth gymnast

Abstract Purpose Rhythmic (RG) and artistic gymnastics (AG) are very popular female sports. These two disciplines share some common points but, at the same time, they display some relevant differences in terms of physical and technical characteristics. The aim of this study was as follows: (1) to clarify how gymnastic training background over the years could lead to the development and motor learning of the motor skills and (2) to highlight differences of conditional skills achieved by RG and AG athletes. Methods For these aims, 45 athletes were selected, belonging to three balanced groups: promotional (PG, n = 15), RG (n = 15), and AG (n = 15). Participants were tested for joints mobility, balance, explosive strength, speed, and endurance tests. Results Statistical analysis showed a good test–retest reliability of the measurements (ICC > 0.870) and some significant differences between PG, RG, and AG. RG showed higher values in joint mobility tests (coxo-femoral mobility, 166.7 ± 6.3°; sit and reach, 20.5 ± 1.9 cm; and scapulo-humeral mobility, 45.5 ± 4.4 cm) with respect to AG, while AG showed higher values in endurance (1626.7 ± 7.4 m), balance (4.33 ± 1.35 n/60 s), and explosive strength (164.1 ± 11.6 cm) compared to RG (p < 0.05). Conclusion RG and AG seem to be effective in enhancing different and sport-specific physical fitness and conditioning. RG enables, indeed, to develop more joints mobility whereas AG improves more strength, balance, and endurance. However, given the small sample size employed, these results should be replicated by further studies utilizing larger samples

Tendinopathy: Pathophysiology, therapeutic options, and role of nutraceutics. a narrative literature review

Tendinopathies are very common in general population and a huge number of tendon-related procedures take place annually worldwide, with significant socio-economic repercussions. Numerous treatment options are commonly used for tendon disorders. Besides pharmacological and physical therapy, nutrition could represent an additional tool for preventing and treating this complex pathology that deserve a multidisciplinary approach. In recent years, nutraceutical products are growing up in popularity since these seem to favor the prevention and the healing processes of tendon injuries. This narrative literature review aims to summarize current understanding and the areas of ongoing research about the management of tendinopathies with the help of oral supplementation

Selective Functional Movement Assessment (SFMA) Reliability and Proposal of Its Use in Sports

Introduction: The Selective Functional Movement Assessment (SFMA) is a functional movement assessment method to observe movement restrictions in individuals with known musculoskeletal disorders, although it has also been used to evaluate healthy athletes of different sports. Aim: The present paper aimed to evaluate the applicability of SFMA in a clinical setting and to verify whether a student can correctly perform it. Methods: An introductory and explanatory email was sent to the subjects, containing the instructions needed to produce a video with SFMA evaluation movements. SFMA methodology was then used to analyze the received videos. The results between interobserver and intraobserver agreement were compared to the literature, considered the gold standard methods. Results: Twenty-eight subjects (17.71 ± 1.96 years aged) were rated. The functional non-painful scenario (FN) has been assigned more frequently by all raters. The student's intra-rater reliability proved to be moderate (Kappa coefficient 0.49). Results for inter-rater reliability showed that the reliability degree between the senior physiotherapist and student before and after their educational path is good (Kappa coefficient 0.60 and 0.62, respectively). Conclusions: The results of this study showed SFMA intra-rater reliability to be moderate, while inter-rater reliability can be considered good. These characteristics make it a valuable tool for sport's needs, even when used by students

Jump and balance test in judo athletes with or without visual impairments

The study was conducted for four months with 8 judo athletes: 4 sighted people (4 M) and 4 visual impairment people (3 M and 1 F), aged between 18 and 52 (30.75 ± 12.74). According to the IBSA Visual Classification, all visual impairment subjects participating in our study were covered in the B1 category of visual deficit. This is a group represented by patients with no light perception in either eye up to light perception, and with an inability to recognize the shape of a hand at any distance or in any direction. From our cohort it was excluded subjects who have had low extremities musculoskeletal, neurological, or orthopaedic disorders in the previous six months. The aim of the study was to evaluate their balance with both closed and opened eyes and to set their lower limbs’ strength: these are indispensable characteristics to carry out technical actions of judo. Anthropometric measures were compared between groups and data about jump protocol and balance protocol were analysed. Results of current research showed that postural stability is different in function of assessment with closed and open eyes. The result of the jump tests differs because the data do not show significant differences between long jump and high jump. The comparison between blinded and sighted judo athletes highlighted greater difficulties with eyes closed for sighted athletes than blinded ones

Limited diagnostic value of questionnaire-based pre-participation screening algorithms: A "risk-exposed" approach to sports activity

Background: Several pre-participation screening algorithms (PPSAs) have been proposed to assess sports eligibility in different populations. They are usually based on self-administered questionnaires, without further medical assessment if no risk factors are documented. The Med-Ex "Formula Benessere"worksite program includes a complete cardiovascular (CV) screening for all participants. The purpose of this study was to assess PPSAs accuracy in detecting medical and/or CV abnormalities in the general population, comparing the results with the date derived from Med-Ex program. Methods: The Med-Ex medical evaluation, consisting of medical history, physical examination (including body composition), resting electrocardiogram (ECG) and exercise stress test in 464 male subjects (38.4 aged) was analyzed and matched to several PPSAs - Physical Activity Readiness Questionnaire (PAR-Q) (2002-2020), American Heart Association (AHA)/American College of Sport Medicine (ACSM) (1998-2009-2014-2015), European Association of Cardiovascular Prevention and Rehabilitation (EACPR) (2011) - retrospectively simulated. Results: Five-hundred and 67 abnormalities were detected though Med-Ex medical evaluation, and one-fourth (24%) would have been undetected applying PPSA alone. In particular 28% of high blood pressure, 21% of impaired fasting glycaemia, 21% of high Body Mass Index (BMI) values and 19% of ECG abnormalities would have been missed, on average, by all PPSAs. Conclusions: The simulation analysis model performed in this study allowed to highlight the limits of PPSAs in granting sport eligibility, compared to a medical-guided CV screening. These findings emphasize the importance of a more balanced approach to pre-participation screening that includes a thorough evaluation of the cost/benefit ratio