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Fábio J. Lanferdini, Rodrigo R. Bini, Pedro Figueiredo, Fernando Diefenthaeler, Carlos B. Mota, Anton Arndt and Marco A. Vaz

Purpose:

To employ cluster analysis to assess if cyclists would opt for different strategies in terms of neuromuscular patterns when pedaling at the power output of their second ventilatory threshold (POVT2) compared with cycling at their maximal power output (POMAX).

Methods:

Twenty athletes performed an incremental cycling test to determine their power output (POMAX and POVT2; first session), and pedal forces, muscle activation, muscle–tendon unit length, and vastus lateralis architecture (fascicle length, pennation angle, and muscle thickness) were recorded (second session) in POMAX and POVT2. Athletes were assigned to 2 clusters based on the behavior of outcome variables at POVT2 and POMAX using cluster analysis.

Results:

Clusters 1 (n = 14) and 2 (n = 6) showed similar power output and oxygen uptake. Cluster 1 presented larger increases in pedal force and knee power than cluster 2, without differences for the index of effectiveness. Cluster 1 presented less variation in knee angle, muscle–tendon unit length, pennation angle, and tendon length than cluster 2. However, clusters 1 and 2 showed similar muscle thickness, fascicle length, and muscle activation. When cycling at POVT2 vs POMAX, cyclists could opt for keeping a constant knee power and pedal-force production, associated with an increase in tendon excursion and a constant fascicle length.

Conclusions:

Increases in power output lead to greater variations in knee angle, muscle–tendon unit length, tendon length, and pennation angle of vastus lateralis for a similar knee-extensor activation and smaller pedal-force changes in cyclists from cluster 2 than in cluster 1.

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In the article by Joseph MF et al, “Incidence of Morphologic Changes in Asymptomatic Achilles Tendons in an Active Young Adult Population,” in J Sport Rehabil. 21(3), 249–252, 3 authors were omitted from the byline. The full list of authors is Michael F. Joseph, Thomas H. Trojian, Jeffrey M. Anderson, John Crowley, Lindsay Dilieto, Brian O’Neil, and Craig R. Denegar.

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Isabelle Schöffl, Thomas Baier and Volker Schöffl

After a pulley rupture, most climbers regain the full function of their previously uninjured fingers. However, in some cases of pulley rupture, a persistent inflammation of the tendon sheath is observed. In this study, 16 cadaver fingers were loaded until pulley rupture and then studied for the rupturing mechanism. In addition, two patients with this pathology were investigated using ultrasound and MRI, and received surgery. In 13 fingers, a rupture of one or several pulleys occurred and almost always at the medial or lateral insertion. In one finger, a capsizing of the pulley underneath the intact tendon sheath was observed, leading to an avulsion between tendon and tendon sheath. A similar pathology was observed in the ultrasound imaging, in MRI, and during surgery in two patients with prolonged recovery after minor pulley rupture. In cases of prolonged tenosynovitis after minor pulley rupture, a capsizing of the pulley stump is probably the cause for constant friction leading to inflammation. In those cases, a surgical removal of the remaining pulley stump and sometimes a pulley repair may be necessary.

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Steffen Willwacher, Wolfgang Potthast, Markus Konrad and Gert-Peter Brüggemann

The purpose of this study was to investigate the effect of heel construction on ankle joint mechanics during the early stance phase of running. Kinematic and kinetic parameters (ankle joint angles, angular velocities and joint moments, lever arms of ground reaction force, triceps surae muscle tendon unit lengths, and rates of muscle tendon unit length change) were calculated from 19 male subjects running at 3.3 m/s in shoes with different heel constructions. Increasing heel height and posterior wedging amplified initial plantar flexion velocity and range. The potential for a muscle to control the movement of a joint depends upon its ability to produce joint moments. Runners in this study showed decreased external eversion moments and an increase in eversion range. Maximum eversion angles were not significantly affected by shoe conditions. Without considerable tendon prestretch, joint moment generation potentials of triceps surae and deep plantar flexors might be inhibited due to rapid plantar flexion based on the force–velocity relationship. It could be speculated that increasing ankle inversion at heel strike could be a strategy to keep maximum eversion angles inside an adequate range, if joint moment generation potentials of deep plantar flexors are inhibited due to rapid plantar flexion.

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Kirsten Legerlotz, Robert Marzilger, Sebastian Bohm and Adamantios Arampatzis

Purpose:

To understand the mechanisms for the effects of resistance training on functional parameters, and to assess the injury risk of the involved tissues, it is necessary to examine the underlying morphological and structural changes of the respective tissues.

Methods:

The presented information on physiological adaptations have been deduced from cross-sectional studies comparing youth athletes with controls and children with adults as well as from longitudinal studies examining the effects of resistance training in untrained children and adolescents and in youth athletes.

Results:

The evidence indicates, that training induced changes in motor performance rely partly on enhanced neuromuscular control, and partly on morphological adaptation of muscles and tendons, such as changes in muscle, muscle fiber and tendon cross-sectional area, muscle composition, and tendon material properties, with the bone also adapting by increasing bone mineral content and cortical area.

Conclusion:

Although the training induced adaptations of the investigated tissues follows similar principles in children as in adults, the magnitude of the adaptive response appears to be more subtle. As studies investigating physiological adaptation in youth athletes are sparse, more research in this area is warranted to elucidate the specific physiological stimulus-response relationship necessary for effective training programs and injury prevention.

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Cori Sinnott, Hayley M. White, Jennifer W. Cuchna and Bonnie L. Van Lunen

Clinical Scenario:

Achilles tendinopathy is a painful condition commonly affecting the general and athletic population. It presents with localized pain, stiffness, and swelling in the midportion of the Achilles tendon. The physical stress placed on the tendon results in microtrauma, which leads to subsequent inflammation and degeneration. While it is not surprising that this condition affects the physically active, nearly one-third of Achilles tendinopathy cases occur in sedentary individuals. Etiology for this condition stems from a change in loading patterns and/or overuse of the tendon, resulting in microscopic tearing and degenerative changes. There are numerous causes contributing to the maladaptive response in these patients, such as mechanical, age-related, genetic, and vascular factors. The treatment for these patients is typically load management and eccentric strengthening of the gastrocnemius–soleus complex. Unfortunately, conservative treatment can lead to surgical intervention in up to 45% of cases. A relatively new phenomenon in the treatment of this condition is the use of autologous blood injections (ABI) and platelet-rich plasma injections (PRPI). This need for a less invasive treatment fostered more investigation into ABI and PRPI to treat these nonresponsive patients. However, the evidence concerning the effectiveness of these treatments in patients with Achilles tendinopathy has not been synthesized.

Focused Clinical Question:

In patients with Achilles tendinopathy, how do variations of ABI and PRPI compared with a placebo and/or eccentric training affect pain and function?

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Liang-Ching Tsai, Irving S. Scher and Christopher M. Powers

The purpose of this study is to describe an MRI-based EMG-driven knee model to quantify tibiofemoral compressive and shear forces. Twelve healthy females participated. Subjects underwent 2 phases of data collection: (1) MRI assessment of the lower extremity to quantify muscle volumes and patella tendon orientation and (2) biomechanical evaluation of a drop-jump task. A subject-specific EMG-driven knee model that incorporated lower extremity kinematics, EMG, and muscle volumes and patella tendon orientation estimated from MRI was developed to quantify tibiofemoral shear and compressive forces. A resultant anterior tibial shear force generated from the ground reaction force (GRF) and muscle forces was observed during the first 30% of the stance phase of the drop-jump task. All of the muscle forces and GRF resulted in tibiofemoral compression, with the quadriceps force being the primary contributor. Acquiring subject-specific muscle volumes and patella tendon orientation for use in an EMG-driven knee model may be useful to quantify tibiofemoral forces in persons with altered patella position or muscle atrophy following knee injury or pathology.

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Zachary K. Winkelmann and Kenneth E. Games

An 18-year-old, male collegiate basketball athlete complained of right testicular pain following basketball activities. The patient’s imaging denoted edema within the pubis at the insertion of the adductor longus tendon and rectus sheath aponeurosis consistent with inguinal disruption. The patient underwent conservative rehabilitation and attempted to return to participation with increased pain. Subsequently, the patient underwent surgery. Following surgical intervention, the patient underwent 6 weeks of rehabilitation with basketball-specific considerations. On conclusion, the patient was pain free and returned to activity. This case is unique due to the insidious onset, sport in which the patient participated, and failed conservative management.

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Jin Hyuck Lee, Ji Soon Park and Woong Kyo Jeong

A 27-year-old man presented with a 5-year history of left periscapular muscle spasm and constant shoulder pain in activities of daily living. Magnetic resonance imaging (MRI) and physical examination revealed scapular dyskinesis without pathologic lesions in the rotator cuff tendon and labrum. However, there was hypertrophy of the serratus anterior muscle on computed tomography (CT). Scapular dyskinesis can be caused by isolated hypertrophy of the serratus anterior. After 4 months of physiotherapy, including manual therapy, therapeutic exercises, and neuromuscular retraining, the patient recovered normal scapular movement and reported no pain.

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Fabien Cignetti, Sébastien Caudron, Marianne Vaugoyeau and Christine Assaiante

There is evidence that adolescence is a critical period in development, most likely involving important modifications of the body schema and of the sensorimotor representations. The present study addressed this issue, by investigating the differences between adolescents and adults regarding the integration of proprioceptive information at both perceptual and postural levels and the visual recognition of human movement. Proprioceptive integration was examined using muscle-tendon vibration that evoked either a postural response or an illusory sensation of movement. The ability to recognize human movement was investigated from a paradigm where the participants had to discern between human movements performed with and without gravity. The study produced three main findings. First, the adolescents had larger postural responses to tendon vibrations than the adults, with visual information enabling them to reduce this exaggerated postural reaction. Second, the adolescents had a greater illusory perception of movement compared with the adults. Third, the adolescents had the same perceptual ability as adults in the human movement perception task. In conclusion, we were able to highlight notable differences between adolescents and young adults, which confirms the late maturation of multisensory integration for postural control and the privileged visual contribution to postural control.