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Gene expression changes in vastus lateralis muscle after different strength training regimes during rehabilitation following anterior cruciate ligament reconstruction.

ABSTRACT: Impaired muscle regeneration has repeatedly been described after anterior cruciate ligament reconstruction (ACL-R). The results of recent studies provided some evidence for negative alterations in knee extensor muscles after ACL-R causing persisting strength deficits in spite of the regain of muscle mass. Accordingly, we observed that 12 weeks of concentric/eccentric quadriceps strength training with eccentric overload (CON/ECC+) induced a significantly greater hypertrophy of the atrophied quadriceps muscle after ACL-R than conventional concentric/eccentric quadriceps strength training (CON/ECC). However, strength deficits persisted and there was an unexpected increase in the proportion of slow type I fibers instead of the expected shift towards a faster muscle phenotype after CON/ECC+. In order to shed further light on muscle recovery after ACL-R, the steady-state levels of 84 marker mRNAs were analyzed in biopsies obtained from the vastus lateralis muscle of 31 subjects before and after 12 weeks of CON/ECC+ (n = 18) or CON/ECC strength training (n = 13) during rehabilitation after ACL-R using a custom RT2 Profiler PCR array. Significant (p < 0.05) changes were detected in the expression of 26 mRNAs, several of them involved in muscle wasting/atrophy. A different pattern with regard to the strength training mode was observed for 16 mRNAs, indicating an enhanced hypertrophic stimulus, mechanical sensing or fast contractility after CON/ECC+. The effects of the type of autograft (quadriceps, QUAD, n = 19, or semitendinosus tendon, SEMI, n = 12) were reflected in the lower expression of 6 mRNAs involved in skeletal muscle hypertrophy or contractility in QUAD. In conclusion, the greater hypertrophic stimulus and mechanical stress induced by CON/ECC+ and a beginning shift towards a faster muscle phenotype after CON/ECC+ might be indicated by significant gene expression changes as well as still ongoing muscle wasting processes and a negative impact of QUAD autograft.

SUBMITTER: Friedmann-Bette B

PROVIDER: S-EPMC8516190 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Pre- and postoperative rehabilitation are important to the management of patients with anterior cruciate ligament (ACL) reconstruction, but little attention has been given to the costs. This study evaluated the pre- and postoperative rehabilitation charges in patients with ACL reconstruction in the United States.Patients receive preoperative rehabilitation less commonly than postoperative rehabilitation.Retrospective database study.Level 4.Using the PearlDiver database, we identified patients undergoing ACL reconstruction from 2007 through 2011 using Current Procedural Terminology codes. The associated rehabilitation charges billed to insurance providers for 90 days preoperatively and 6 months postoperatively were categorized as physical therapy or as durable medical equipment (DME). The charges were examined by year and geographic region and represented as per-patient average charges (PPACs).A total of 92,179 patients were identified in the study period. The PPAC for rehabilitation was $241 during the 90-day preoperative period and $1876 for the 6-month postoperative period. Patients averaged 2 preoperative sessions for physical therapy, with 44% of patients receiving preoperative rehabilitation in contrast with an average of 17 postoperative sessions per patient in 93% of patients. Rehabilitation charges were greater postoperatively than preoperatively (P < 0.05). Preoperatively, 24% of patients received a DME, while 35% received a DME postoperatively. Preoperative rehabilitation PPACs were highest in the Northeast, followed by Midwest, South, and West (P < 0.05). There were no significant differences in postoperative rehabilitation PPACs for geographic region (P = 0.43).Preoperative rehabilitation charges were lower than postoperative charges. A patient undergoing ACL reconstruction typically received 9 times more sessions of postoperative physical therapy than preoperative.This study found that preoperative supervised rehabilitation for patients with ACL reconstruction was infrequent across the United States.

Project description:BackgroundAfter anterior cruciate ligament (ACL) reconstruction (ACLR), biomechanical asymmetries during gait are highly prevalent, persistent, and linked to posttraumatic knee osteoarthritis. Quadriceps strength is an important clinical measure associated with preoperative gait asymmetries and postoperative function and is a primary criterion for return-to-sport clearance. Evidence relating symmetry in quadriceps strength with gait biomechanics is limited to preoperative and early rehabilitation time points before return-to-sport training.Purpose/hypothesisThe purpose was to determine the relationship between symmetry in isometric quadriceps strength and gait biomechanics after return-to-sport training in athletes after ACLR. We hypothesized that as quadriceps strength symmetry increases, athletes will demonstrate more symmetric knee joint biomechanics, including tibiofemoral joint loading during gait.Study designCross-sectional study; Level of evidence, 3.MethodsOf 79 athletes enrolled in the ACL-SPORTS Trial, 76 were participants in this study after completing postoperative rehabilitation and 10 return-to-sport training sessions (mean ± SD, 7.1 ± 2.0 months after ACLR). All participants completed biomechanical walking gait analysis and isometric quadriceps strength assessment using an electromechanical dynamometer. Quadriceps strength was calculated using a limb symmetry index (involved limb value / uninvolved limb value × 100). The biomechanical variables of interest included peak knee flexion angle, peak knee internal extension moment, sagittal plane knee excursion at weight acceptance and midstance, quadriceps muscle force at peak knee flexion angle, and peak medial compartment contact force. Spearman rank correlation (ρ) coefficients were used to determine the relationship between limb symmetry indexes in quadriceps strength and each biomechanical variable; alpha was set to .05.ResultsOf the 76 participants, 27 (35%) demonstrated asymmetries in quadriceps strength, defined by quadriceps strength symmetry <90% (n = 23) or >110% (n = 4) (range, 56.9%-131.7%). For the biomechanical variables of interest, 67% demonstrated asymmetry in peak knee flexion angle; 68% and 83% in knee excursion during weight acceptance and midstance, respectively; 74% in internal peak knee extension moment; 57% in medial compartment contact force; and 74% in quadriceps muscle force. There were no significant correlations between quadriceps strength index and limb symmetry indexes for any biomechanical variable after return-to-sport training (P > .129).ConclusionAmong those who completed return-to-sport training after ACLR, subsequent quadriceps strength symmetry was not correlated with the persistent asymmetries in gait biomechanics. After a threshold of quadriceps strength is reached, restoring strength alone may not ameliorate gait asymmetries, and current clinical interventions and return-to-sport training may not adequately target gait.

Project description:BackgroundThigh muscle weakness after anterior cruciate ligament reconstruction (ACLR) can persist after returning to activity. While resistance training can improve muscle function, "nonfunctional" training methods are not optimal for inducing transfer of benefits to activities such as walking. Here, we tested the feasibility of a novel functional resistance training (FRT) approach to restore strength and function in an individual with ACLR.HypothesisFRT would improve knee strength and function after ACLR.Study designCase report.Level of evidenceLevel 5.MethodsA 15-year-old male patient volunteered for an 8-week intervention where he performed 30 minutes of treadmill walking, 3 times per week, while wearing a custom-designed knee brace that provided resistance to the thigh muscles of his ACLR leg. Thigh strength, gait mechanics, and corticospinal and spinal excitability were assessed before and immediately after the 8-week intervention. Voluntary muscle activation was evaluated immediately after the intervention.ResultsKnee extensor and flexor strength increased in the ACLR leg from pre- to posttraining (130 to 225 N·m [+74%] and 44 to 88 N·m [+99%], respectively) and increases in between-limb extensor and flexor strength symmetry (45% to 92% [+74%] and 47% to 72% [+65%], respectively) were also noted. After the intervention, voluntary muscle activation in the ACLR leg was 72%, compared with the non-ACLR leg at 75%. Knee angle and moment during late stance phase decreased (ie, improved) in the ACLR leg and appeared more similar to the non-ACLR leg after FRT training (18° to 14° [-23.4] and 0.07 to -0.02 N·m·kg-1·m-1 [-122.8%], respectively). Corticospinal and spinal excitability in the ACLR leg decreased (3511 to 2511 [-28.5%] and 0.42 to 0.24 [-43.7%], respectively) from pre- to posttraining.ConclusionA full 8 weeks of FRT that targeted both quadriceps and hamstring muscles lead to improvements in strength and gait, suggesting that FRT may constitute a promising and practical alternative to traditional methods of resistance training.Clinical relevanceFRT may serve as a viable approach to improve knee strength and function after ACL reconstruction.

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Gene expression changes in vastus lateralis muscle after different strength training regimes during rehabilitation following anterior cruciate ligament reconstruction.

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