Perineuronal Nets Play a Role in Regulating Striatal Function in the Mouse

The striatum is the primary input nucleus of the basal ganglia, a collection of nuclei that play important roles in motor control and associative learning. We have previously reported that perineuronal nets (PNNs), aggregations of chondroitin-sulfate proteoglycans (CSPGs), form in the matrix compartment of the mouse striatum during the second postnatal week. This period overlaps with important developmental changes, including the attainment of an adult-like gait. Here, we investigate the identity of the cells encapsulated by PNNs, characterize their topographical distribution and determine their function by assessing the impact of enzymatic digestion of PNNs on two striatum-dependent behaviors: ambulation and goal-directed spatial learning. We show PNNs are more numerous caudally, and that a substantial fraction (41%) of these structures surrounds parvalbumin positive (PV+) interneurons, while approximately 51% of PV+ cells are ensheathed by PNNs. The colocalization of these structures is greatest in dorsal, lateral and caudal regions of the striatum. Bilateral digestion of striatal PNNs led to an increase in both the width and variability of hind limb gait. Intriguingly, this also resulted in an improvement in the acquisition rate of the Morris water maze. Together, these data show that PNNs are associated with specific elements of striatal circuits and play a key role in regulating the function of this important structure in the mouse

A three-experiment examination of iliotibial band strain characteristics during different conditions using musculoskeletal simulation.

PURPOSE: Iliotibial band syndrome (ITBS) is a common chronic pathology mediated via excessive Iliotibial band (ITB) strain. The purpose using a three-experiment approach is to provide insight into the differences in strain between different athletic movements, the incidence of ITBS in females, the efficacy of different prophylactic modalities for ITBS and also the kinematic parameters associated with ITB strain. METHODS: Experiment 1 examined male and female athletes performing run, 45° cut and one-legged hop movements, experiment 2 observed males and females, whilst running in five different orthotic conditions and experiment 3 examined males and females riding a cycle ergometer at 70, 80 and 90RPM whilst in prophylactic knee brace and no-brace conditions. In each experiment, kinematics were obtained using a motion capture system and ITB strain was measured using a musculoskeletal simulation approach. RESULTS: In experiment 1 ITB strain was greater in the run (male=3.87% & female=4.37%; P<0.001) and cut (male=3.12% & female=4.06%; P<0.001) movements compared to hop (male=0.87% & female=1.54%). Experiment 2 showed that females exhibited increased ITB strain (male=6.34% & female=8.91%; P<0.05) and ITB strain velocity (male=57.17%/s & female=77.41%/s; P<0.05) and also in females that ITB strain velocity was greater (P≤0.01) in lateral (80.22%/s) and no-orthotic (83.01%/s) conditions compared to medial (72.58%/s) and off the shelf orthoses (74.52%/s). The regression analyses across movements showed that ITB strain was predicted by sagittal and coronal plane mechanics at the hip (R2=0.15-0.30; P<0.05) and sagittal, coronal and transverse plane kinematics at the knee joint (R2=0.15-0.22; P<0.05). CONCLUSION: Further insight is provided into differences in ITB strain across functional athletic movements, the increased incidence of ITBS in females and the parameters linked most strongly with ITB strain during different movements is provided; whilst also highlighting the prophylactic efficacy of medial and off the shelf orthoses in female runners

Influência do treinamento excêntrico nas razões de torque de flexores/extensores do joelho

O treinamento excêntrico (Texc) produz adaptações musculares que minimizam a ocorrência de lesões e é usado em reabilitação e treinamento de força, mas pouco se sabe sobre seus efeitos no equilíbrio entre músculos antagonistas do joelho. As razões de torque permitem determinar esses desequilíbrios musculares. O objetivo do estudo foi avaliar os efeitos de 12 semanas de Texc nas razões de torque excêntrico (Iexc:Qexc) entre os músculos isquiotibiais (I) e quadríceps (Q). Vinte e quatro sujeitos saudáveis do sexo masculino foram distribuídos nos grupos controle (GC, n=13, idade 27,7±4,6 anos) e experimental (GE, n=11, idade 28,5±9,5 anos), submetido ao treinamento. Um dinamômetro isocinético foi utilizado para o Texc (velocidade de -60 º/s) e para as avaliações (uma a cada quatro semanas). As razões de torque medidas foram comparadas estatisticamente entre os grupos e intragrupos entre as avaliações, com nível de significância de 5%. No GE, foi observada redução das razões de torque da avaliação (AV) inicial para as demais: AV1x AV2, p=0,005; AV1x AV3, p=0,001; e AV1x AV4, pEccentric training produces skeletal muscle adaptations that help preventing muscle injuries, being often used in rehabilitation and physical fitness programs, but little is known of the effects of this training in the balance between knee antagonistic muscles. Torque ratios allow determining such balance. The purpose of this study was to assess the effect of a 12-week eccentric training program on the eccentric torque ratio between hamstring and quadriceps muscles (Hecc:Qecc). Twenty-four healthy male subjects were assigned to either a control group (CG, n=13, aged 27.7±4.6 years) or an experimental group (EG, n=11, aged 28.5±9.5 years). An isokinetic dinamometer was used (angular velocity -60º/s) for both the eccentric training and the assessments, performed every four weeks. Torque ratios measured were statistically compared between groups and intragroups between assessments, with (significance level set at p<0.05. In EG a reduction in torque ratios was found from the initial assessment (AS1) to the other three ones: AS1x AS2, p=0.005; AS1x AS3, p=0.001; and AS1x AS4, p<0.001. At the last evaluation, EG torque ratios were lower than those of CG's (p=0.041). Eccentric training hence changes balance between knee flexor and extensor muscles: a 12-week training program leads to lower Hecc:Qecc ratio and to extensor torque increase, with no significant change in flexor torque, being thus suitable for rehabilitation aimed at strengthening knee extensor muscles

Incidence and prevalence of patellofemoral pain: a systematic review and meta-analysis

Background: Patellofemoral pain is considered one of the most common forms of knee pain, affecting adults, adolescents, and physically active populations. Inconsistencies in reported incidence and prevalence exist and in relation to the allocation of healthcare and research funding, there is a clear need to accurately understand the epidemiology of patellofemoral pain. Methods: An electronic database search was conducted, as well as grey literature databases, from inception to June 2017. Two authors independently selected studies, extracted data and appraised methodological quality. If heterogeneous, data were analysed descriptively. Where studies were homogeneous, data were pooled through a meta-analysis. Results: 23 studies were included. Annual prevalence for patellofemoral pain in the general population was reported as 22.7%, and adolescents as 28.9%. Incidence rates in military recruits ranged from 9.7 – 571.4/1,000 person-years, amateur runners in the general population at 1080.5/1,000 person-years and adolescents amateur athletes 5.1% - 14.9% over 1 season. One study reported point prevalence within military populations as 13.5%. The pooled estimate for point prevalence in adolescents was 7.2% (95% Confidence Interval: 6.3% - 8.3%), and in female only adolescent athletes was 22.7% (95% Confidence Interval 17.4% - 28.0%). Conclusion: This review demonstrates high incidence and prevalence levels for patellofemoral pain. Within the context of this, and poor long term prognosis and high disability levels, PFP should be an urgent research priority