Effetti cardiorespiratori degli sprint ripetuti in giovani calciatori

Scopo: Nel calcio la performance dipende da attività caratterizzate da sforzi di breve durata, talora ad alta intensità, con ridotti tempi di recupero. Questo tipo di sforzo può avere maggiore potenzialità aritmogena rispetto a sforzi, anche massimali, iniziati e terminati in modo graduale. Gli sprint ripetuti permettono di valutare la performance e lo stato di allenamento in giovani calciatori. Scopo del nostro lavoro è stato quello di valutare gli effetti degli sprint ripetuti sul sistema cardiorespiratorio in giovani calciatori delle rappresentative regionali siciliane della FIGC. Metodi: Sono stati esaminati 12 calciatori, di età media di 15±1 anni. Per valutare lo stato di fitness cardiorespiratoria sono stati determinati, al test da sforzo incrementale massimale al treadmill (SI), il VO2max in ml.Kg-1.min-1 (VO2maxSI) e la FCmax in bpm (FCmaxSI). Per valutare gli effetti cardiorespiratori degli sprint ripetuti, gli atleti hanno eseguito un test da sforzo al cicloergometro a freno meccanico (SR) che prevedeva 10 sprint massimali “all-out” di 6 sec, intervallati da 30 sec di recupero passivo. Nella serie dei 10 sprint, sono stati determinati il valore più elevato di VO2 in ml.Kg-1.min-1 (VO2maxSR) e di FC in bpm (FCmaxSR). Risultati: Il valore medio di VO2maxSI (56,22±3,93 ml.Kg-1.min-1) indica che i soggetti esaminati hanno un buon livello di potenza aerobica, raggiunta ad una FCmaxSI di 190±8 bpm. I dati di VO2maxSR rilevati al test degli sprint ripetuti evidenziano un valore medio di 42,67±5,57 ml.Kg-1.min-1 (70% del VO2maxSI), raggiunto ad una FCmaxSR di 175±11 bpm (92% della FCmaxSI). Conclusioni: I dati del nostro studio indicano che nei soggetti esaminati gli sprint ripetuti determinano incrementi della frequenza cardiaca rapidi, elevati e persistenti nella fase di recupero. Questo dato deve essere preso in considerazione non solo per la valutazione della performance ma anche nella formulazione dell’idoneità a praticare la disciplina sportiva del calcio

Analysis of anaerobic power in club level young rowers

Aim: To date, assessment of the anaerobic components to determine performance in rowers is not part of standard evaluation or monitoring set for training. The aim of this study was to evaluate the relation between anaerobic power output and ergometer rowing performance over 2000 meters, in a group of 14 -17 years old rowers (n = 11). Methods: Each subject performed, in three separate days, two “all-out” tests, over 20 and 60 seconds, and a 2000 meters trial, using a Concept II rowing ergometer. Mean power values over 20 sec (W20) and 60 sec (W60) were measured and compared with the time to perform the 2000 m trial (t2000). Results: Statistical analysis showed high and significant correlation between 2000 meters performance (6.90 ± 0.1 min) and anaerobic power over 20 sec (479.5 ± 93.90 watts; r = 0.941, P = 0.00002) and 60 sec (435.5 ± 64.60 watts; r = 0.964, P = 0.000002). Conclusions: The data of our study confirm that parameters of anaerobic power strongly affect the performance and that the determination of these variables by testing on rowing ergometer can be an useful tool for planning and monitoring of training in young rowers

Fracture of Ceramic Bearing Surfaces following Total Hip Replacement: A Systematic Review

Ceramic bearing surfaces are increasingly used for total hip replacement, notwithstanding that concern is still related to ceramic brittleness and its possible mechanical failure. The aim of this systematic review is to answer three questions: (1) Are there risk factors for ceramic component fracture following total hip replacement? (2) Is it possible to perform an early diagnosis of ceramic component failure before catastrophic fracture occurs? (3) Is it possible to draw guidelines for revision surgery after ceramic components failure? A PubMed and Google Scholar search was performed and reference citations from publications identified in the literature search were reviewed. The use of 28\u2009mm short-neck femoral head carries an increased risk of fracture. Acetabular component malposition might increase the risk of ceramic liner fractures. Synovial fluid microanalysis and CT scan are promising in early diagnosis of ceramic head and liner failure. Early revision is suggested in case of component failure; no consensus exists about the better coupling for revision surgery. Ceramic brittleness remains a major concern. Due to the increased number of ceramic on ceramic implants, more revision surgeries and reports on ceramic components failure are expected in the future. An algorithm of diagnosis and treatment for ceramic hip failure is proposed

3DBGrowth: volumetric vertebrae segmentation and reconstruction in magnetic resonance imaging

Segmentation of medical images is critical for making several processes of analysis and classification more reliable. With the growing number of people presenting back pain and related problems, the semi-automatic segmentation and 3D reconstruction of vertebral bodies became even more important to support decision making. A 3D reconstruction allows a fast and objective analysis of each vertebrae condition, which may play a major role in surgical planning and evaluation of suitable treatments. In this paper, we propose 3DBGrowth, which develops a 3D reconstruction over the efficient Balanced Growth method for 2D images. We also take advantage of the slope coefficient from the annotation time to reduce the total number of annotated slices, reducing the time spent on manual annotation. We show experimental results on a representative dataset with 17 MRI exams demonstrating that our approach significantly outperforms the competitors and, on average, only 37% of the total slices with vertebral body content must be annotated without losing performance/accuracy. Compared to the state-of-the-art methods, we have achieved a Dice Score gain of over 5% with comparable processing time. Moreover, 3DBGrowth works well with imprecise seed points, which reduces the time spent on manual annotation by the specialist.Comment: This is a pre-print of an article published in Computer-Based Medical Systems. The final authenticated version is available online at: https://doi.org/10.1109/CBMS.2019.0009

Relationship Between Heart Rate Recovery After Exercise and Maximal Oxygen Uptake in Sedentary Patients with Type 2 Diabetes

AIMS: Heart rate recovery after exercise (HRR) is an estimate of autonomic modulation of the heart, and has been shown to be inversely associated with type 2 diabetes. Type 2 diabetes is associated with decreased maximal oxygen consumption (VO2max). Aim of our study was to assess the relationship between HRR and VO2max in sedentary patients with type 2 diabetes. METHODS: Maximal exercise testing to determine VO2max (ml ∙ Kg-1 ∙ min-1) was performed in 16 sedentary patients with type 2 diabetes (DP) and in 16 age-matched sedentary healthy controls (HS). HRR (bpm) 2 min after cessation of the exercise was recorded. Simple linear regression was used to assess the relations between HRR and VO2max. RESULTS: VO2max and HRR were significantly lower in DP compared to HS (P = 0.002 and P = 0.008 respectively). A correlation between HRR and VO2max has been found, stronger in DP (r = 0.672, P = 0.004) than HS (r = 0.620, P = 0.01). CONCLUSIONS: Our study suggests that regular physical activity aimed to improve the levels of VO2max in subjects with diabetes may improve the HRR and reduce the risk of cardiovascular events

Relationship between heart rate variability and repeated sprint exercise in young soccer players

Aim: The sport of soccer is characterized by neuromuscular performance resulting in short bursts interspersed by brief recovery periods over an extended period of time. Several studies suggest that the cardiac autonomic nervous system (ANS) assessed by heart rate variability (HRV) may provide useful information regarding the functional adaptations to training stimulus. Although HRV has often been associated with aerobic power and cardiovascular fitness, the influence of sympathovagal balance on neuromuscular performance in young athletes is not well assessed. The aim of this study was to assess the influence of the autonomic system on the performance of repeated sprints, involving predominantly muscular power and anaerobic metabolism, in young soccer players. Method: Twelve young soccer players, selected for the Sicilian Regional Representative of the Italian Football Federation, mean age 15 years, were recruited. Resting HRV was measured and indices of power spectral analysis (ratio LF/HF) were calculated to evaluate the sympathovagal balance. To assess the state of physical fitness of subjects, VO2max was determined by maximal graded treadmill test. Finally, the athletes performed 10 maximal all-out 6-sec cycling sprints (RS), interspersed with 30-sec of passive recovery, to measure the peak power (PP) represented by the highest value recorded during a single sprint, and the average of the values of maximum power (AP) recorded during all sprints. Results: On the basis of their VO2max (56.22 ± 3.93 ml/Kg/min), all subjects showed good levels of physical fitness. HRV index (LF/HF = 1.31 ± 0.74) showed an inverse correlation with PP (14.05 ± 0.89 W/Kg; r = -0.709, P = 0.01), and with AP (12.82 ± 0.88 W/Kg; r = -0.606, P = 0.04). Conclusion: Our study shows that a low ratio LF/HF, which reflects a parasympathetic predominance in the ANS balance, is associated with a better anaerobic contribution to performance resulting in higher values of PP and AP during brief repeated maximal cycling sprints. The assessment of resting HRV before exercise may be useful for performance monitoring of young soccer players

Influence of occlusal vertical dimension on cervical spine mobility in sports subjects

Introduction: In the scientific literature, a number of studies have reported conflicting results regarding the effects of occlusal vertical dimension (OVD) on sports-related skills. The purpose of this study was to increase OVD in sports subjects so as to specifically investigate the influence on cervical spine mobility. In particular, we measured cervical range of motion (ROM) before and after increasing OVD in individuals, either with or without malocclusion, analyzing both sports and sedentary subjects. Materials and methods: Participants were divided into two groups: a sports group (SG) and a control group (CG), each including 18 subjects. The SG was composed of sports subjects (age: 20.11±3.45 yrs; BMI: 25.39±2.32 kg/m2), whereas the CG consisted of age-matched sedentary subjects (age: 25.78±2.26 yrs; BMI: 24.88±2.87 kg/m2). Cervical range of motion (ROM) was evaluated, by way of an accelerometer (Moover®, Sensor Medica®), before (pre-test) and after (post-test) increasing OVD. Results: The main finding of this study was that sports subjects showed no significant difference, compared to control subjects, in cervical ROM in response to increased OVD. Moreover, we found that sports and sedentary subjects alike showed no significant change in cervical spine mobility as a result of increased OVD, regardless of whether they were affected by malocclusion (class II) or represented subjects with normocclusion (class I). Conclusion: In accord with several studies reported in the literature, the findings of our study indicate that occlusal splints failed to significantly improve the physical-performance endpoint measured, i.e. cervical ROM, in sports subjects as compared to sedentary individuals. Due to the paucity of studies, characterized by conflicting results, there is as yet no compelling scientific evidence as to whether OVD positively impacts sports performance or not. Accordingly, we suggest that further scientific investigation, regarding the relationship between sports performance and OVD, be conducted in the field of sport and exercise sciences