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Many patients with anterior cruciate ligament (ACL) injuries have persistent quadriceps muscle atrophy, even after considerable time in rehabilitation. Understanding the factors that regulate muscle mass, and the time course of atrophic events, is important for identifying therapeutic interventions. With a noninvasive animal model of ACL injury, a longitudinal study was performed to elucidate key parameters underlying quadriceps muscle atrophy. Male Long-Evans rats were euthanized at 6, 12, 24, or 48 h or 1, 2, or 4 wk after ACL injury that was induced via tibial compression overload; controls were not injured. Vastus lateralis muscle size was determined by wet weight and fiber cross-sectional area (CSA). Evidence of disrupted neuromuscular communication was assessed via the expression of neural cell adhesion molecule (NCAM) and genes associated with denervation and neuromuscular junction instability. Abundance of muscle RING-finger protein-1 (MuRF-1), muscle atrophy F-box (MAFbx), and 45 s pre-rRNA along with 20S proteasome activity were determined to investigate mechanisms related to muscle atrophy. Finally, muscle damage-related parameters were assessed by measuring IgG permeability, centronucleation, CD68 mRNA, and satellite cell abundance. When compared with controls, we observed a greater percentage of NCAM-positive fibers at 6 h postinjury, followed by higher MAFbx abundance 48 h postinjury, and higher 20S proteasome activity at 1 wk postinjury. A loss of muscle wet weight, smaller fiber CSA, and the elevated expression of run-related transcription factor 1 (Runx1) were also observed at the 1 wk postinjury timepoint relative to controls. There also were no differences observed in any damage markers. These results indicate that alterations in neuromuscular communication precede the upregulation of atrophic factors that regulate quadriceps muscle mass early after noninvasive ACL injury. NEW & NOTEWORTHY A novel preclinical model of ACL injury was used to establish that acute disruptions in neuromuscular communication precede atrophic events. These data help to establish the time course of muscle atrophy after ACL injury, suggesting that clinical care may benefit from the application of acute neurogenic interventions and early gait reloading strategies.

Doxycycline has been shown to reduce fibroblast activity in the treatment of multiple pathologies, and was utilized as part of the postoperative medication protocol to help prevent adhesions from developing after hip arthroscopy. The purpose of this study was to compare early postoperative pain outcomes between consecutive case series of femoroacetabular impingement syndrome (FAIS) patients treated with or without a 7-day postoperative course of doxycycline following hip arthroscopy. We hypothesized that the doxycycline-treated group would have superior patient-reported outcomes at 6 weeks, and the effect would be more pronounced for patients with low preoperative mental health scores.Our institutional review board–approved prospective outcomes registry was queried for patients who had undergone arthroscopic femoral osteochondroplasty and/or labral repair or reconstruction secondary to FAIS performed by a single, fellowship-trained surgeon. A 7-day postoperative course of doxycycline was initiated in 2018. Six-week postoperative Hip Disability and Osteoarthritis Outcome Score (HOOS) global (HOOSglobal) and International Hip Outcome Tool (iHOT) scores were compared between the consecutive series treated with versus without doxycycline. Additional subgroup analysis was performed on patients with low preoperative Veterans RAND 12-Item Health Survey (VR-12) mental component scores to determine possible additional benefit of postoperative doxycycline in this group.A total of 134 patients (98 female, 36 male, age = 36.2 ± 13.4 years, body mass index [BMI] = 27.2 ± 5 kg/m2) were identified between 2013 and 2020. There were no differences between the control (n = 84) and doxycycline group (n = 50) in age, sex, or BMI. Postoperative HOOSglobal scores (control = 58.5 ± 13.1, doxycycline = 58.7 ± 14.7, p = 0.96) and iHOT scores (control = 54.4 ± 22.2, doxycycline = 52.3 ± 24.8, p = 0.61) did not differ between groups. The subset of 83 patients with low preoperative mental scores showed no differences in HOOSglobal (control = 51.6 ± 13.3, doxycycline = 57.3 ± 7.4, p = 0.12) or iHOT scores (control = 45.5 ± 20.3, doxycycline = 53.6 ± 23.1, p = 0.250).Our results do not support the hypothesis that postoperative doxycycline leads to significant improvement in early postoperative pain scores or functional outcomes in patients undergoing hip arthroscopy for FAIS.

Background: Anterior cruciate ligament reconstruction (ACLR) results in persistent altered knee biomechanics, but contributing factors such as pain or patient function, leading to the altered loading, are unknown. Hypothesis: Individuals with worse self-reported pain after ACLR would have poorer biomechanics during running, and poor loading mechanics would be present in the ACLR limb compared with contralateral and control limbs. Study Design: Cohort pilot study. Level of Evidence: Level 3. Methods: A total of 20 patients after ACLR (age, 18.4 ± 2.7 years; height, 1.7 ± 0.1 m; mass, 84.2 ± 19.4 kg) completed visual analog scale and Knee Injury and Osteoarthritis Outcomes Score (KOOS) at 1 and 6 months postsurgery. At 6 months postsurgery, patients underwent biomechanical testing during running. A total of 20 control individuals also completed running biomechanical analyses. Associations between patient outcomes and biomechanics were conducted, and differences in running biomechanics between groups were analyzed. Results: KOOS pain score 1 month after surgery was associated with peak ACLR knee abduction moment ( R2 = 0.35; P = 0.01). At 6-months, KOOS sport score was related to peak abduction moment in the ACLR limb ( R2 = 0.23; P = 0.05). For change scores, the improvement in pain scores related to ACLR limb peak knee abduction moment ( R2 = 0.55; P = 0.001). The ACLR limb had lower knee excursion, extension moments, and ground-reaction forces compared with the uninvolved and control limb. The uninvolved limb also had higher ground-reaction forces compared with the ACLR limb and control limb. Conclusion: These results suggest that patient-reported outcomes 1 and 6 months after surgery are associated with running mechanics 6 months after ACLR. Further, the underloading present in the ACLR limb and overloading in the uninvolved limb indicates greater need for running rehabilitation after ACLR. Clinical Relevance: Understanding pain and how it may be linked to movement dysfunction is important for improving long-term outcomes.

Anterior cruciate ligament (ACL) injury initiates a biochemical cascade thought to contribute to the onset and progression of posttraumatic osteoarthritis (PTOA). Interleukin-1ß (IL-1ß), IL-6, and C-telopeptide fragments of type II collagen (CTX-II) are implicated in joint inflammation and cartilage degradation following ACL injury; however, their association with pain is still being explored. The purpose of this study was to evaluate the associations between synovial fluid concentrations of IL-1ß, IL-6, and CTX-II with pain following ACL injury and reconstruction. We hypothesized that greater IL-1ß, IL-6, and CTX-II would correlate with greater Pain Visual Analogue Scale (VAS) scores. This was a secondary analysis of 23 patients (mean age = 18.4 years, BMI = 27.4, 13 females/10 males) with acute ACL tears who participated in a pilot randomized trial. Synovial fluid and VAS scores were collected on the day of initial presentation, at ACL reconstruction, and 1 and 4 weeks after surgery. Synovial fluid concentrations of IL-1ß, IL-6, and CTX-II were assessed using enzyme-linked immunoabsorbent assays, and repeated measures correlations were used to assess the relationships between pain and synovial IL-1ß, IL-6, or CTX-II after ACL injury and reconstruction. Pain was positively correlated with synovial fluid IL-6 concentrations (r = 0.52, p 0.001); however, pain was inversely correlated with CTX-II (r = -0.39, p = 0.002). IL-1ß had no significant correlation with pain. Statement of clinical relevance: PTOA has been described as a "silent killer" and these results suggest that early PTOA may have pro-inflammatory pathways that are not primarily associated with pain but still lead to progressive cartilage loss.

Anterior cruciate ligament (ACL) injury leads to a sustained increase in synovial fluid concentrations of inflammatory cytokines and biomarkers of cartilage breakdown. While this has been documented post-injury, it remains unclear whether ACL reconstruction surgery contributes to the inflammatory process and/or cartilage breakdown. This study is a secondary analysis of 14 patients (nine males/five females, mean age = 9, mean BMI = 28) enrolled in an IRB-approved randomized clinical trial. Arthrocentesis was performed at initial presentation (mean = 6 days post-injury), immediately prior to surgery (mean = 23 days post-injury), 1-week post-surgery, and 1-month post-surgery. Enzyme-linked immunosorbant assay kits were used to determine concentrations of carboxy-terminal telopeptides of type II collagen (CTXII), interleukin-6 (IL-6), and IL-1β in the synovial fluid. The log-transformed IL-1β was not normally distributed; therefore, changes between time points were evaluated using a non-parametric Kruskal-Wallis one-way ANOVA. IL-1β concentrations significantly increased from the day of surgery to the first postoperative time point (P ≤ .001) and significantly decreased at the 4-week postoperative visit (P = .03). IL-1β concentrations at the 4-week postoperative visit remained significantly greater than both preoperative time points (P .05). IL-6 concentrations at 1-week post-surgery were significantly higher than at initial presentation (P = .013), the day of surgery (P .001), and 4 weeks after surgery (P = .002). CTX-II concentrations did not differ between the first three-time points (P .99) but significantly increased at 4 weeks post-surgery (P .01). ACL reconstruction appears to reinitiate an inflammatory response followed by an increase in markers for cartilage degradation. ACL reconstruction appears to initiate a second "inflammatory hit" resulting in increased chondral breakdown suggesting that post-operative chondroprotection may be needed.

Massage is a viable mechanotherapy to improve protein turnover during disuse atrophy and improve muscle regrowth during recovery from disuse atrophy in adult muscle. Therefore, we investigated whether massage can cause beneficial adaptations in skeletal muscle from aged rats during normal weight-bearing (WB) conditions, hindlimb suspension (HS), or reloading (RE) following HS. Aged (30 months) male Fischer 344/Brown Norway rats were divided into two experiments: (1) WB for 7 days (WB, n = 8), WB with massage (WBM, n = 8), HS for 7 days (HS7, n = 8), or HS with massage (HSM, n = 8), and (2) WB for 14 days (WB14, n = 8), HS for 14 days (HS14, n = 8), reloading (RE, n = 10), or reloading with massage (REM, n = 10) for 7 days following HS. Deuterium oxide (D(2)O) labeling was used to assess dynamic protein and ribosome turnover in each group and anabolic signaling pathways were assessed. Massage did have an anabolic benefit during RE or WB. In contrast, massage during HS enhanced myofibrillar protein turnover in both the massaged limb and contralateral non-massaged limb compared with HS, but this did not prevent muscle loss. Overall, the data demonstrate that massage is not an effective mechanotherapy for prevention of atrophy during muscle disuse or recovery of muscle mass during reloading in aged rats. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s11357-020-00215-y) contains supplementary material, which is available to authorized users.

Context Long-term eccentric exercise is known to promote muscle growth better than concentric exercise, but its acute effect on muscle is not well understood because of misinterpreted modeling and in situ and in vitro stretch protocols. Knowing if the initial bout of eccentric exercise promotes muscle growth and limits damage is critical to understanding the effect of this mode of exercise. Objective To directly evaluate the immediate effects of eccentric and concentric exercises on untrained muscle when fiber strains were physiological and exercise doses were comparable. Design Controlled laboratory study. Setting Laboratory. Patients or Other Participants A total of 40 skeletally mature male Long-Evans rats (age = 16 weeks, mass = 452.1 ± 35.2 g) were randomly assigned to an eccentric exercise (downhill walking, n = 16), concentric exercise (uphill walking, n = 16), or control (no exercise, n = 8) group. Intervention(s) Rats were exposed to a single 15-minute bout of eccentric or concentric exercise on a motorized treadmill and then were euthanized at 6 or 24 hours postexercise. We harvested the vastus lateralis muscle bilaterally. Main Outcome Measure(s) The percentage increase or decrease in protein abundance in exercised animals relative to that in unexercised control animals was evaluated as elevated phosphorylated p70S6k relative to total p70S6k. Fiber damage was quantified using immunoglobulin G permeability staining. One-way analysis of variance and post hoc Tukey tests were performed. Results Rats exposed to eccentric exercise and euthanized at 24 hours had higher percentage response protein synthesis rates than rats exposed to eccentric exercise and euthanized at 6 hours (P = .02) or to concentric exercise and euthanized at 6 (P = .03) or 24 (P = .03) hours. We assessed 9446 fibers for damage and found only 1 fiber was infiltrated (in the concentric exercise group euthanized at 6 hours). Furthermore, no between-groups differences in immunoglobulin G fluorescent intensity were detected (P = .94). Conclusions Incorporating eccentric exercise is a simple, universally available therapeutic intervention for promoting muscle recovery. A single 15-minute dose of eccentric exercise to a novice muscle can better exert an anabolic effect than a comparable dose of concentric exercise, with very limited evidence of fiber damage.

Cyclic compressive loading (CCL) is a massage mimetic that improves muscle regrowth from atrophy in adult rats. Therefore, we tested if a single bout of CCL increases anabolic signaling and protein synthesis in muscle during normal, weight-bearing conditions in gastrocnemius muscle from adult and aged rats. Male Brown Norway/F344 rats at 10 (adult) and 30 (aged) months of age were assigned control or CCL (receiving a single bout of CCL). Twenty-four hours following a single bout of CCL there was no change in protein synthesis, Akt, or GSK3β signaling at either age, despite adult rats having higher abundance and activation of mechanosensitive pathways (integrins and integrin-linked kinase). Murf1 was elevated in response to CCL in both age groups, potentially indicating muscle remodeling. Muscle from aged rats exhibited an increase in heat shock protein (HSP) 25 and HSP70 and in the cold shock protein RNA-binding motif 3 (RBM3), demonstrating a unique stress response to CCL in aged muscle only. Finally, muscle from aged rats exhibited higher basal protein synthesis that was corroborated by elevated eIF2Bε and rpS6 signaling, without an additional effect of CCL. In summary, a single bout of CCL does not have anabolic effects on skeletal muscle during normal, weight-bearing conditions, even though it has previously been shown to improve regrowth from atrophy. These data demonstrate that interventions that may help recover from atrophy do not necessarily induce muscle hypertrophy in unperturbed conditions. NEW & NOTEWORTHY Massage has been demonstrated to be an effective mechanotherapy to improve recovery from atrophy in adult skeletal muscle; however, this study shows that a single bout of massage fails to increase protein synthesis or anabolic signaling in adult or aged skeletal muscle during normal, weight-bearing conditions. Altogether, our data suggest massage is a useful mechanotherapy for preserving skeletal muscle when combined with other interventions but is not an anabolic stimulus on its own.

Anterior cruciate ligament (ACL) injury causes a deleterious cascade of events including increased inflammation and cartilage breakdown. Increases in pro-inflammatory cytokines following injury begin almost immediately following ACL rupture and include upregulations in inflammatory pathways. New evidence is emerging that elucidates the proteomic response to ACL injury and demonstrates that the beginning stages of post-traumatic osteoarthritis (PTOA) are more similar to rheumatoid arthritis than idiopathic osteoarthritis. Furthermore, in-depth studies of ACL patient populations reveals a subset of patients that presents a dysregulated inflammatory response following injury. These patients have an increased inflammatory burden and a more robust pro-inflammatory reaction to acute injury. While this subset of patients does not represent all of those who will go on to develop PTOA, the differences in individualized inflammatory responses are important to consider in treatment. Moreover, ACL reconstruction surgery presents a second and potentially larger insult to the joint resulting in the re-initiation of inflammation and an increase in cartilage breakdown. This “second hit” triggers a sustained inflammatory response following surgery that does not return back to pre-operative levels and persists for at least 5 years after reconstruction. There are many factors to consider when determining treatment including the timing of treatment, dosing, and return to activity guidelines. Due to the large secondary hit from surgery, treatment post-operatively, rather than pre-operatively, will likely be more effective. Furthermore, extended-release treatment options and how loading may affect the inflammatory process during the resumption of physical activities should all be taken into consideration.

In conjunction with cartilage breakdown, muscle maladaptation including atrophy and increased fibrosis have been observed in the quadriceps following anterior cruciate ligament (ACL) injury. Previously observed upregulated muscle-related proteins in the synovial fluid following ACL rupture allude to cellular communication between the joint and muscle. Therefore, the purpose of this study was to determine whether muscle-related analytes are differentially expressed in the serum. Sixteen patients with an acute ACL tear participated in this IRB-approved study. Serum was obtained at two different time points at a mean of 6 and 14 days post-injury, and serum was analyzed by a highly multiplexed assay of 1,300 proteins. Pathway analysis using DAVID was performed; genes included met three criteria: significant change between the two study time points using a paired t test, significant change between the two study time points using a Mann-Whitney non-parametric test, and significant Benjamini post hoc analysis. Twelve analytes significantly increased between time points. Proteins chitinase-3-like protein 1 (p = 0.01), insulin-like growth factor binding protein 1 (p = 0.01), insulin-like growth factor binding protein 5 (p = 0.02), renin (p = 0.004), and lymphotoxin alpha 1: beta 2 (p = 0.03) were significantly upregulated in serum following acute ACL injury. The current results confirm the inflammatory pattern previously seen in the synovial fluid thought to play a role in the progression of post-traumatic osteoarthritis after ACL injury, and this data also provides further insights into important communication between the joint and quadriceps group, whose function is important in long term health. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:387-392, 2020.

PURPOSE Elevated synovial fluid (SF) concentrations of proinflammatory cytokines, degradative enzymes, and cartilage breakdown markers at the time of anterior cruciate ligament (ACL) reconstruction are associated with worse postoperative patient-reported outcomes and cartilage quality. However, it remains unclear if this is due to a more robust or dysregulated inflammatory response or is a function of a more severe injury. The objective of this study was to evaluate the association of the molecular composition of the SF, patient demographics, and injury characteristics to cartilage degradation after acute ACL injury. METHODS We performed a cluster analysis of SF concentrations of proinflammatory and anti-inflammatory cytokines, and biomarkers of cartilage degradation, bony remodeling, and hemarthrosis. We evaluated the association of biomarker clusters with patient demographics, days between injury, Visual Analogue Scale pain, SF aspirate volumes, and bone bruise volumes measured on magnetic resonance imaging. RESULTS Two clusters were identified from the 35 patients included in this analysis, dysregulated inflammation and low inflammation. The dysregulated inflammation cluster consisted of 10 patients and demonstrated significantly greater concentrations of biomarkers of cartilage degradation (P < 0.05) as well as a lower ratio of anti-inflammatory to proinflammatory cytokines (P = 0.053) when compared with the low inflammation cluster. Patient demographics, bone bruise volumes, SF aspirate volumes, pain, and concomitant injuries did not differ between clusters. CONCLUSIONS A subset of patients exhibited dysregulation of the inflammatory response after acute ACL injury which may increase the risk of posttraumatic osteoarthritis. This response does not appear to be a function of injury severity.

Massage is a common therapeutic modality utilized by clinicians in a variety of settings to help treat injuries, reduce pain, and return function to patients. Massage benefits the patients both psychologically and physiologically, as patients report less pain and anxiety along with better mood and even decreased blood pressure following massage. Additionally, on the cellular level, massage has the ability to modulate the damaging inflammatory process and, in some cases, influence protein synthesis. Although massage has not been linked to a rehabilitation theory to date, this paper will propose how massage may influence fear-avoidance beliefs, or the patient’s inability to cope with pain that then leads to a pain tension cycle. Pain will often result in use avoidance, which creates muscle tension that further exacerbates the pain. Massage can affect the Fear-Avoidance Model because the beneficial effects of massage can break the cycle by either relieving the patient’s pain or eliminating the muscle tension. A modified Fear-Avoidance Model is presented that conceptualizes how pain and fear-avoidance lead to tension and muscle dysfunction. Massage has been incorporated into the model to demonstrate its potential for breaking the pain tension cycle. This model has the potential to be applied in clinical settings and provides an alternate treatment to patients with chronic pain who present with increased levels of fear-avoidance beliefs.

Aim Interventions that decrease atrophy during disuse are desperately needed to maintain muscle mass. We recently found that massage as a mechanotherapy can improve muscle regrowth following disuse atrophy. Therefore, we aimed to determine if massage has similar anabolic effects when applied during normal weight bearing conditions (WB) or during atrophy induced by hindlimb suspension (HS) in adult rats. Methods Adult (10 months) male Fischer344-Brown Norway rats underwent either hindlimb suspension (HS, n = 8) or normal WB (WB, n = 8) for 7 days. Massage was applied using cyclic compressive loading (CCL) in WB (WBM, n = 9) or HS rats (HSM, n = 9) and included four 30-minute bouts of CCL applied to gastrocnemius muscle every other day. Results Massage had no effect on any anabolic parameter measured under WB conditions (WBM). In contrast, massage during HS (HSM) stimulated protein turnover, but did not mitigate muscle atrophy. Atrophy from HS was caused by both lowered protein synthesis and higher degradation. HS and HSM had lowered total RNA compared with WB and this was the result of significantly higher ribosome degradation in HS that was attenuated in HSM, without differences in ribosomal biogenesis. Also, massage increased protein turnover in the non-massaged contralateral limb during HS. Finally, we determined that total RNA degradation primarily dictates loss of muscle ribosomal content during disuse atrophy. Conclusion We conclude that massage is an effective mechanotherapy to impact protein turnover during muscle disuse in both the massaged and non-massaged contralateral muscle, but it does not attenuate the loss of muscle mass.

Based on extensive research on the relationship between exercise and health, exercise as a form of medicine is a powerful concept of growing popularity within healthcare, academia and policy. Proponents of this exercise is medicine (EiM) movement frame exercise as a panacea for a variety of health issues and uncritically promote exercise as good for all. Two clinical populations particularly influenced by the EiM agenda are spinal cord injury (SCI) and arthritis. The purpose of this research was to explore how individuals with SCI and arthritis personally make sense of their exercise experiences. Data were collected through semi-structured interviews with 10 participants with SCI and 20 participants with arthritis. Following a thematic narrative analysis, three patterns were identified across the whole data set. These were: 1) exercise and restitution; 2) exercise and pain; and 3) exercise and pleasure. Taken together, these results provide new knowledge regarding the impact of exercise that both align with, and contrast, the dominant EiM discourse. When exercise is perceived as ‘medicine’, stories of exercise participation spoke of cure, and restitution, rather than health and well-being. Pain was an unwelcomed side effect of exercise participation for some, and had a detrimental impact upon motivation and engagement. Lastly, a focus upon the medicinal benefits of exercise did not reflect the multiple pleasures experienced through exercise participation. Thus, health professionals, academics and policy makers need to prescribe to more ethical forms of exercise promotion that may lead to more efficacious, person-sensitive interventions.

Massage, in the form of cyclic compressive loading (CCL), is associated with multiple health benefits, but its potential anabolic effect on atrophied muscle has not been investigated. We hypothesized that the mechanical activity associated with CCL induces an anabolic effect in skeletal muscle undergoing regrowth after a period of atrophy. Fisher/Brown Norway rats at 10 months of age were hind limb unloaded for a period of 2 weeks. The rats were then allowed reambulation with CCL applied at a 4.5 N load at 0.5 Hz frequency for 30 min every other day for 4 bouts during a regrowth period of 8 days. Muscle fibre cross sectional area was enhanced by 18% with massage during regrowth compared to reloading alone, and this was accompanied by elevated myofibrillar and cytosolic protein as well as DNA synthesis. Focal adhesion kinase (FAK) phosphorylation indicated that CCL increased mechanical stimulation, while a higher number of Pax7+ cells likely explains the elevated DNA synthesis. Surprisingly, the contralateral non-massaged limb exhibited a comparable 17% higher muscle fibre size compared to reloading alone, and myofibrillar protein synthesis, but not DNA synthesis, was also elevated. We conclude that massage in the form of CCL induces an anabolic response in muscles regrowing after an atrophy-inducing event. We suggest that massage can be used as an intervention to aid in the regrowth of muscle lost during immobilization. This article is protected by copyright. All rights reserved

Massage is a widely accepted manual therapy used to modulate the inflammatory response of muscle and restore function, but prolonged compression of muscle potentially causes overt injury and damage to muscle fibers. Therefore, a balance exists between the positive effects of massage and the induction of mechanical damage and injury. In addition, skeletal muscle of aged individuals displays increased stiffness, and therefore, the response to massage is likely different compared with young. We hypothesized that the aged skeletal muscle exhibits increased sarcolemmal permeability when subjected to massage compared with young skeletal muscle. Male Brown Norway/F344 rats, 10 and 30 months of age, were each divided into control, non‐massaged (n = 8) and massaged (n = 8) groups. The right gastrocnemius muscle received one bout of cyclic compressive loading for 30 min at 4.5 N as a massage‐mimetic. Muscles were dissected and frozen 24 h after massage. Alterations in sarcolemma permeability were quantified by measuring the level of intracellular IgG within the muscle fibers. Immunohistochemistry was performed to determine IgG inside fibers and Pax7+ cell number as an indicator of stem cell abundance. Average IgG intensity was not different between control and massaged animals at either age. However, a significant shift to the right of the density histogram indicated that massaged animals had more fibers with higher IgG intensity than control at 10 months. In addition, Pax7+ cell number was significantly elevated in massaged muscles compared with control at both ages. One bout of massage did not induce overt muscle injury, but facilitated membrane permeability, which was associated with an increase in satellite cell number. Data suggest that the load applied here, which was previously shown to induce immunomodulatory changes, does not induce overt muscle injury in young and old muscles but may result in muscle remodeling. Funded by NIH grant AG042699 and AT009268.

Maintenance of skeletal muscle (SkM) mass is essential for maintaining mobility and metabolic health. SkM unloading or disuse, such as extended bed rest or limb immobilization, leads to rapid SkM w...

Clinical Scenario: Anterior cruciate ligament (ACL) ruptures are one of the most common injuries in young athletic populations. The leading treatment for these injuries is ACL reconstruction (ACL-r); however, nonoperative treatments are also utilized. Following ACL-r, patients experience prolonged muscle weakness and atrophy of the quadriceps muscle group, regardless of rehabilitation. Nonoperative treatment plans following ACL injury exist, but their outcomes are less familiar, in spite of providing insight as a nonsurgical “control” for postsurgical rehabilitation outcomes. Therefore, the purpose of this critically appraised topic was to evaluate quadriceps strength and function following nonoperative ACL rehabilitation using objective and subjective measures including isokinetic dynamometry, the single-leg hop test, and the International Knee Documentation Committee (IKDC) subjective knee form. Focused Clinical Question: What are the effects of nonoperative treatment on peak isokinetic knee-extensor torque, the single-leg hop tests, and the IKDC in patients who have sustained an ACL rupture? Summary of Key Findings: Patients who underwent nonsurgical ACL treatment produced limb symmetry index, with the side-to-side torque difference expressed as a percentage, and values at or above 90% for all 4 single-leg hop tests and strength tests similar to ACL-r patients. All studies showed individuals had higher IKDC scores at baseline collection when compared with patients who underwent ACL-r but showed lower IKDC scores at long-term follow-up compared with ACL-r patients. Clinical Bottom Line: Nonoperative treatments of ACL injuries yield similar long-term results in quadriceps strength as ACL-r. Due to the quality of evidence and the absence of randomized controlled trials on this topic, these outcomes should be considered with caution. Strength of Recommendation: The Oxford Centre for Evidence-Based Medicine taxonomy recommends a grade of B for level 2 evidence with consistent findings.

Sports injury research has predominantly focused on acute injuries, often overlooking the complexities that may be associated with chronic injury. Consequently, the aim of the present study was to understand the experiences of individuals who continued to take part in sport with a chronic injury. Using a narrative methodology, 10 athletes who had experienced chronic pain for at least one year took part in interviews which asked them to narrate their story of pain. Results identify the imprisonment narrative used to describe chronic injury and consider that the causes of this “imprisonment” may be both physical and environmental. Further, this study illustrates how athletes have coped with chronic pain, emphasizing the body-self relationship and the difficulties associated with adapted sport. These findings have important implications for practitioners working with injured athletes, emphasizing that the experiences of athletes in chronic pain may differ considerably from those in acute pain.