Medial Patellofemoral Ligament Reconstruction Using Pedicled Quadriceps Tendon Autograft Yields Similar Clinical and Patient-Reported Outcomes but Less Donor-Site Morbidity Compared With Gracilis Tendon Autograft.

PURPOSE: To compare clinical and patient-reported outcome measures (PROMs) in patients with recurrent patellar dislocation after medial patellofemoral ligament (MPFL) reconstruction using either a gracilis tendon (GT) or quadriceps tendon autograft (QT). METHODS: All MPFL reconstruction performed between 2017 and 2019 were reviewed retrospectively. Only patients with isolated MPFL reconstruction, without any major patellofemoral risk factors and a minimum follow-up of 24 months, were included in the study. Patients were matched with respect to sex, age, and body mass index. All patients were evaluated clinically and using PROMs. RESULTS: A total of 64 patients with an average follow up of 28.7 ± 7.5 months were included in this study. The mean Kujala score (GT: 84.8 ± 12.9, QT: 88.9 ± 10.1), Lysholm score (GT: 89.4 ± 10.2, QT: 88.4 ± 5.0), and visual analog scale score for pain (GT: 1.9 ± 1.8, QT: 1.1 ± 1.3) did not significantly differ between both groups. Tegner activity level was significantly greater (P = .027) in the QT group (5.5 ± 1.9) compared with the GT group (4.6 ± 1.8), but within the minimal clinically important differences. Occasional patellar instability events, but no recurrent dislocation, were reported in 12.5% in the GT group and 6.3% in the QT group (P = .39). Of all patients, 90.6% in the QT and 68.8% in the HT group exceeded the PASS for the Kujala score (P = .06). Significantly more patients (59.4%) treated with GT reported donor-site morbidity in the form of sensitivity deficit at the lower leg compared with those treated with QT (3.1%, P = .001). CONCLUSIONS: GT and QT MPFL reconstruction have comparable PROMs and patellar redislocation rates 2 years' postoperatively. Significantly more patients treated with GT reported lower-leg sensitivity deficit compared with those treated with QT. LEVEL OF EVIDENCE: Level III, retrospective case-control study.

Body Composition of Competitive Bodybuilders: A Systematic Review of Published Data and Recommendations for Future Work.

ABSTRACT: Bauer, P, Majisik, A, Mitter, B, Csapo, R, Tschan, H, Hume, P, Martínez-Rodríguez, A, and Makivic, B. Body composition of competitive bodybuilders: a systematic review of published data and recommendations for future work. J Strength Cond Res 37(3): 726-732, 2023-The purpose of this review was to systematically summarize studies measuring the body composition of competitive bodybuilding athletes to provide recommended values for preparation and during competition. The protocol was preregistered with PROSPERO (CRD42020197921) and followed the guidelines of the Preferred Reported Items for Systematic Reviews and Meta-Analysis. A search of 5 electronic databases (PubMed, Web of Science, SportDiscus, CINAHL, and Scopus) was conducted to retrieve all relevant publications from January 1, 2000, up to June 13, 2021. Of 16 studies meeting the inclusion criteria, 6 presented longitudinal data on competition preparation and were discussed in detail. In the general preparation phase, body fat levels of bodybuilding athletes ranged between 15.3 and 25.2% (female) and from 9.6 to 16.3% (male). Close to competition, however, body fat levels were substantially lower, ranging from 8.1 to 18.3% for female and 5.8-10.7% for male athletes. All studies comparing relative body fat values at various time points during competition preparation found significant reductions between 30 and 60% in relative body fat, whereas lean mass was mostly maintained. Findings from the studies included in this review suggest that most bodybuilding competitors keep resistance training volume high while increasing aerobic training volume when preparing for competition. Findings on energy intake and macronutrient distribution were unclear and should be addressed in future studies. Further research, especially on contest preparation, is warranted and should include more details about training programs, nutritional strategies, psychosocial situation, anabolic androgen steroid, and supplement use as well as measurement protocols and preparation.

Neuromuscular adaptations after 12 weeks of light- vs. heavy-load power-oriented resistance training in older adults.

This study aimed to determine the specific adaptations provoked by power-oriented resistance training using light (LL-PT, 40% 1-RM) vs. heavy (HL-PT, 80% 1-RM) loads in older adults. Using a randomized within-subject study design, 45 older adults (>65 years) completed an 8-week control period (CTR) followed by 12 weeks of unilateral LL-PT vs. HL-PT on a leg press. The 1-RM, theoretical force at zero velocity (F0 ), maximal unloaded velocity (V0 ), and maximal muscle power (Pmax ) were determined through a force-velocity relationship test. Isometrically, the rate of force development (RFD) and the corresponding muscle excitation of the knee extensor muscles were assessed. In addition, muscle cross-sectional area (CSA) and architecture of two quadriceps muscles were determined. Changes after CTR, LL-PT and HL-PT were compared using linear mixed models. HL-PT provoked greater improvements in 1-RM and F0 (effect size (ES) = 0.55-0.68; p < 0.001) than those observed after LL-PT (ES = 0.27-0.47; p ≤ 0.001) (post hoc treatment effect, p ≤ 0.057). By contrast, ES of changes in V0 was greater in LL-PT compared to HL-PT (ES = 0.71, p < 0.001 vs. ES = 0.39, p < 0.001), but this difference was not statistically significant. Both power training interventions elicited a moderate increase in Pmax (ES = 0.65-0.69, p < 0.001). Only LL-PT improved early RFD (ie, ≤100 ms) and muscle excitation (ES = 0.36-0.60, p < 0.05). Increased CSA were noted after both power training programs (ES = 0.13-0.35, p < 0.035), whereas pennation angle increased only after HL-PT (ES = 0.37, p = 0.004). In conclusion, HL-PT seems to be more effective in improving the capability to generate large forces, whereas LL-PT appears to trigger greater gains in movement velocity in older adults. However, both interventions promoted similar increases in muscle power as well as muscle hypertrophy.

Mechanical Characteristics of Heavy vs. Light Load Ballistic Resistance Training in Older Adults.

ABSTRACT: Rodriguez-Lopez, C, Alcazar, J, Sánchez-Martín, C, Ara, I, Csapo, R, and Alegre, LM. Mechanical characteristics in heavy vs. light load ballistic resistance training in older adults. J Strength Cond Res 36(8): 2094-2101, 2022-Although power-oriented resistance training (RT) is strongly recommended to counter age-related neuromuscular function declines, there is still controversy about which intensities of load should be used to elicit optimal training adaptations. Knowledge of the mechanical characteristics of power-oriented RT performed at different intensities might help to better understand the training stimulus that triggers load-dependent adaptations in older adults. Using a cross-over design, 15 well-functioning older volunteers (9 men and 6 women; 73.6 ± 3.8 years) completed 2 volume × load-matched ballistic RT sessions with heavy (HL: 6 × 6 × 80% 1-repetition maximum [1RM]) and light-load (LL: 6 × 12 × 40% 1RM) on a horizontal leg press exercise. Electromyographic (EMG) and mechanical variables (work, force, velocity, and power) as well as intraset neuromuscular fatigue (i.e., relative losses in force, velocity, and power) were analyzed. More concentric mechanical work was performed in the LL training session, compared with HL (36.2 ± 11.2%; p < 0.001). Despite the higher mean EMG activity of the quadriceps femoris muscle (13.2 ± 21.1%; p = 0.038) and greater concentric force (35.2 ± 7.6%; p < 0.001) during HL, higher concentric velocity (41.0 ± 12.7%, p < 0.001) and a trend toward higher concentric power (7.2 ± 18.9%, p = 0.075) were found for LL. Relative velocity losses were similar in both sessions (≈10%); however, relative force losses were only found in LL (7.4 ± 6.5%, p = 0.003). Considering the greater mechanical work performed and concentric power generated, ballistic RT using LL may, therefore, represent a stronger stimulus driving training adaptations as compared with volume × load-matched heavy-load training. Relative losses in force and power should be monitored in addition to velocity losses during ballistic RT.

Acute Physiological Response to Light- and Heavy-load Power-oriented Exercise in Older Adults.

This study investigated the acute responses to volume-load-matched heavy-load (80% 1RM) versus light-load (40% 1RM) power-oriented resistance training sessions in well-functioning older adults. Using a randomized cross-over design, 15 volunteers completed each condition on a leg press. Neuromuscular (maximal isometric force and rate of force development) and functional performance (power during sit-to-stand test), lactate, and muscle damage biochemistry (creatine kinase, lactate dehydrogenase and C-reactive protein serum concentration) were assessed pre- and post-exercise. Performance declines were found after heavy-load (Cohen's d effect size (d); maximal isometric force=0.95 d; rate of force development=1.17 d; sit-to-stand power =0.38 d, all p<0.05) and light-load (maximal isometric force=0.45 d; rate of force development=0.9 d; sit-to-stand power=1.17 d, all p<0.05), while lactate concentration increased only after light-load (1.7 d, p=0.001). However, no differences were found between conditions (all p>0.05). Both conditions increased creatine kinase the day after exercise (marginal effect=0.75 d, p<0.001), but no other blood markers increased (all, p>0.05). Irrespective of the load used, power training induced non-clinically significant decreases in sit-to-stand performance, moderate declines in maximal isometric force, but pronounced decreases in the rate of force development. Furthermore, the metabolic stress and muscle damage were minor; both sessions were generally well tolerated by well-functioning older adults without previous experience in resistance training.

Contralateral ACL tears strongly contribute to high rates of secondary ACL injuries in professional ski racers.

PURPOSE: To analyse the effects of graft selection, sex, injury complexity and time to return to competition on the odds to suffer secondary ACL injury (either re-rupture or contralateral ACL tear) in professional alpine skiers. METHODS: The database of a specialised joint surgery clinic was screened for professional alpine skiers who had participated in competitions at the FIS race, European Cup and World Cup level prior to having to undergo a primary ACL reconstruction, and who had returned to the same competitional level at least one year prior to the end of the observation period. The rates of secondary ACL injuries were statistically compared between athletes with hamstring and quadriceps tendon autografts, men and women, simple and complex (involvement of menisci or cartilage) primary ACL injuries, and between early (≤ 300 days after primary reconstruction) and late (> 300 days) returners to competition. RESULTS: Fourteen out of the 30 athletes included (46.7%) suffered secondary ACL injuries on average 29.4 ± 22.5 months after primary reconstruction. The secondary injuries comprised five re-ruptures (16.7%) and nine contralateral ACL tears (30.0%). The odds to suffer contralateral ACL tears were non-significantly higher in patients with hamstring tendon autografts (OR 5.69, n.s.) and in those whose primary injuries were classified as simple ACL tears (OR 5.31, n.s.). None of the factors assessed was associated with the odds of graft failure. CONCLUSION: The odds of ACL-injured professional alpine ski racers to suffer secondary ACL tears are nearly 50%, with subsequent contralateral ACL injuries being more common than graft failures. While statistical significance could not be established due to a lack of power, greater odds of contralateral ACL tears were observed in athletes with hamstring tendon grafts as well as those with simple primary ACL injuries. No factors potentially predisposing athletes for graft failure could be identified. LEVEL OF EVIDENCE: III.

The evaluation of Rolimeter, KLT, KiRA and KT-1000 arthrometer in healthy individuals shows acceptable intra-rater but poor inter-rater reliability in the measurement of anterior tibial knee translation.

PURPOSE: To assess measurement equivalence, inter- and intra-rater reliability, standard error of measurements (SEM) and false positive measurements (FPM) of four different knee arthrometers (KLT,Karl Storz; KiRA, I + ; KT-1000 MEDmetric Corp; Rolimeter, Aircast) in healthy patients. METHODS: Four different investigators (two advanced (AR) and two beginners (BR)) examined 12 participants with healthy knees at two time points with regards to anterior tibial translation (ATT) and side-to-side difference (SSD). Test equivalence was assessed using the TOST (two-one-sided t test) procedure with ± 1 mm equivalence boundaries. Intraclass correlation coefficients (ICCs) were calculated using two-way mixed effects models. Furthermore, false positive-(SSD > 3 mm) and SEMs were assessed. RESULTS: A total of 2304 Lachman Tests were performed. Between-rater SSDs were equivalent between AR and BR raters for the Rolimeter only. Inter-rater ICC values (SSD, ATT) were graded as "poor" to "moderate" for all devices. Equivalent test-retest results were observed for all raters using the Rolimeter, KLT and KT-1000, whereas measurement consistency with KiRA was given in the advanced examiners group only. Intra-rater ICC values (Range: SSD, ATT) were graded as "poor" to "moderate" for SSD values and "moderate" to "good" for ATT. SEMs were lowest for the Rolimeter and highest for KiRA. FPM were never obtained with the Rolimeter (0%), twice (2.1%) with the KT-1000, three times (3.1%) with the KLT and 33 times (34.4%) using KiRA. CONCLUSION: There is acceptable intra-rater but poor inter-rater reliability with all tested arthrometers. Measures of knee laxity are comparable between Rolimeter, KLT and KT-1000 but higher for KiRA. Clinically, the present study shows that repeated arthrometry measurements should always be performed by the same investigators.

Additional acromioclavicular cerclage limits lateral tilt of the scapula in patients with arthroscopically assisted coracoclavicular ligament reconstruction.

INTRODUCTION: The current treatment for acromioclavicular (AC) dislocation lacks a gold standard and previous literature concludes that coracoclavicular (CC) fixation with additional AC cerclage fixation adds stability and is a useful adjunct to augment these repairs. AIM: The purpose of this study was to investigate the clinical and radiological value of an additional AC cerclage. It was hypothesised that an additional AC cerclage would show better clinical results. We further expected the additional AC cerclage to result in lower radiological loss of reduction compared to the technique relying on CC-fixation only. METHODS: A total of 30 male patients with acute (less than 3 weeks) AC-dislocations Rockwood grade IV and V from 2013 to 2014 underwent arthroscopic bi-cortical CC-ligament reconstruction. Patients were assigned to a surgeon depending on the day of clinical presentation. One surgeon used only bi-cortical CC-ligament reconstruction (no-PDS group); the other surgeons used an additional PDS cerclage with an 8-loop configuration over the AC joint (PDS group). Clinical data (Constant Shoulder Score, ASES Score, DASH Score, VAS pain) were assessed 24 months post-operatively, and AP shoulder radiographs used to measure the AC and CC distances. RESULTS: No significant differences in the Constant (Z = - 0.498, p = 0.624), ASES (Z = 0.263, p = 0.806) and DASH (Z = 1.097, p = 0.305) score as well as VAS pain (Z = 0.498, p = 0.624) were seen for both groups. Factorial ANOVA showed a significant effect of "time" [F(1,28) = 17.54, p < 0.001, r = 0.62], reflecting a significant radiological increase of AC distances over time for both groups. Comparing CC and CC + AC groups, the effect of "OP technique" was significant [F(1,28) = 4.67, p = 0.039, r = 0.38], with AC distances obtained in the PDS group being statistically lower than in the No-PDS group, whereas CC distances did not significantly increase in both groups [F(1,28) = 0.07, p = 0.791]. "Time × OP technique" interaction effects were non-significant [F(1,28) = 0.38, p = 0.545], which reflects similar changes in AC distances over time in both groups. For the CC distances, neither main nor interaction effects were significant (all p > 0.05). CONCLUSION: Both the isolated CC reconstruction and the CC reconstruction with an additional AC cerclage showed good clinical results at 2 years' follow-up. AC distances increased in both groups from the post-surgery measurement to the 2-year follow-up, but were generally lower with an additional AC cerclage. CC distances did not increase significantly over time in both groups. Therefore, the presented data suggest adding a fixation of the AC joint.

Sonographic evaluation of lateral meniscal extrusion: implementation and validation.

INTRODUCTION: Meniscal extrusion (ME) is an important indicator of and prognostic factor for various knee pathologies. To date, no standardized protocol for the ultrasound-based examination of lateral ME exists. The purpose of the present study was to test the reliability and validity of lateral ME measurements using a standardized ultrasound-based examination protocol. MATERIALS AND METHODS: A group consisting of 11 healthy volunteers (Group I, male and female, 18-45 years) as well as a group of 10 consecutive patients who had undergone all-inside lateral meniscal radial tear repair were included (Group II, male and female, 23-43 years). Lateral ME, the main outcome parameter, was measured by ultrasound (US; both groups) and magnetic resonance imaging (MRI; Group II only). Both knees of all subjects were examined in an unloaded state and under axial compression of the knee (50% of body weight). Repeated measurements obtained in Group I by 2 observers were used for reliability testing, and the validity of US was assessed through comparison with MRI data (Group II). RESULTS: A total of 66 US images of Group I, obtained by each observer, were analyzed for reliability testing. Forty US and MR images of Group II were assessed for validation. Results showed good interrater (ICC = 0.904) and excellent intrarater (ICC = 0.942) reliability of US-based measurements of lateral ME. Agreement with MRI results was poor (ICC = 0.439), with US systematically overestimating results by 1.1 mm on average. CONCLUSIONS: Ultrasound is a reliable, quick and cost-effective technique for lateral ME measurement, but results are not readily comparable with MRI. TRIAL REGISTRATION: The study was registered in the European Union Clinical Trials Register (EudraCT-Number: 2017-005037-24).

Remodeling the Skeletal Muscle Extracellular Matrix in Older Age-Effects of Acute Exercise Stimuli on Gene Expression.

With advancing age, the skeletal muscle extracellular matrix (ECM) undergoes fibrotic changes that may lead to increased muscle stiffness, injury susceptibility and strength loss. This study tested the potential of different exercises to counter these changes by stimulating the activity of genes associated with ECM remodeling. Twenty-six healthy men (66.9 ± 3.9 years) were stratified to two of four groups, performing unilateral (i) conventional resistance exercise, (ii) conventional resistance exercise followed by self-myofascial release (CEBR), (iii) eccentric-only exercise (ECC) or (iv) plyometric jumps (PLY). The non-trained leg served as control. Six hours post-exercise, vastus lateralis muscle biopsy samples were analyzed for the expression of genes associated with ECM collagen synthesis (COL1A1), matrix metallopeptidases (collagen degradation; MMPs) and peptidase inhibitors (TIMP1). Significant between-group differences were found for MMP3, MMP15 and TIMP1, with the greatest responses in MMP3 and TIMP1 seen in CEBR and in MMP15 in ECC. MMP9 (3.24-3.81-fold change) and COL1A1 (1.47-2.40-fold change) were increased in CEBR and PLY, although between-group differences were non-significant. The expression of ECM-related genes is exercise-specific, with CEBR and PLY triggering either earlier or stronger remodeling than other stimuli. Training studies will test whether execution of such exercises may help counter age-associated muscle fibrosis.

Diffusion tensor imaging and diffusion modeling: Application to monitoring changes in the medial gastrocnemius in disuse atrophy induced by unilateral limb suspension.

BACKGROUND: Diffusion tensor imaging (DTI) assesses underlying tissue microstructure, and has been applied to studying skeletal muscle. Unloading of the lower leg causes decreases in muscle force, mass, and muscle protein synthesis as well as changes in muscle architecture. PURPOSE: To monitor the change in DTI indices in the medial gastrocnemius (MG) after 4-week unilateral limb suspension (ULLS) and to explore the feasibility of extracting tissue microstructural parameters based on a two-compartment diffusion model. STUDY TYPE: Prospective cohort study. SUBJECTS: Seven moderately active subjects (29.1 ± 5.7 years). FIELD STRENGTH/SEQUENCE: 3T, single-shot fat-suppressed echo planar spin echo sequence. ASSESSMENT: Suspension-related changes in the DTI indices (eigenvalues: λ1 , λ2 , λ3 , fractional anisotropy; coefficient of planarity) were statistically analyzed. Changes in model-derived tissue parameters (muscle fiber circularity and diameter, intracellular volume fraction, and residence time) after suspension are qualitatively discussed. STATISTICAL TESTS: Changes in the DTI indices of the MG between pre- and postsuspension were assessed using repeated-measures two-way analysis of variance (ANOVA). RESULTS: All the eigenvalues (λ1 : P = 0.025, λ2 : P = 0.035, λ3 : P = 0.049) as well as anisotropic diffusion coefficient (P = 0.029) were significantly smaller post-ULLS. Diffusion modeling revealed that fibers were more circular (circularity index increased from 0.55 to 0.95) with a smaller diameter (diameter decreased from 82-60 µm) postsuspension. DATA CONCLUSION: We have shown that DTI indices change with disuse and modeling can relate these voxel level changes to changes in the tissue microarchitecture. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018.

Relationship of changes in strain rate indices estimated from velocity-encoded MR imaging to loss of muscle force following disuse atrophy.

PURPOSE: This study explores changes in strain rate (SR) (rate of regional deformation) parameters extracted from velocity-encoded MRI and their relationship to muscle force loss following 4-week unilateral lower limb suspension in healthy humans. METHODS: Two-dimensional SR maps were derived from three directional velocity-encoded MR phase-contrast images of the medial gastrocnemius in seven subjects. Atrophy-related and regional differences in the SR eigenvalues, angle between the SR and muscle fiber (SR-fiber angle), and strain rates in the fiber basis were statistically analyzed using analysis of variance and linear regression. RESULTS: During isometric contraction, SR in the fiber cross section (SRin-plane ) was significantly lower, and the SR-fiber angle was significantly higher postsuspension (P < 0.05). On multiple variable regression analysis, the volume of medial gastrocnemius, SRin-plane , and SR-fiber angle were significantly associated with force and changes in the, and the SR eigenvalues and shear SR were significantly associated with change in force with disuse. CONCLUSIONS: Changes in SR-fiber angle, SRin-plane , and shear SR as well as their ability to predict force and force changes may reflect the role of remodeling of the extracellular matrix in disuse atrophy and its functional consequence in reducing lateral transmission of force. Magn Reson Med 79:912-922, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Shear strain rate from phase contrast velocity encoded MRI: Application to study effects of aging in the medial gastrocnemius muscle.

BACKGROUND: Strain rate (SR) is a measure of the rate of regional deformation that can be computed by analyzing velocity-encoded phase-contrast 2D images. Recent studies have explored the changes in normal components of the strain tensor in aging muscle, while shear strain may also provide valuable information. PURPOSE: To compute the shear SR from velocity-encoded MRI of the lower leg and to study the correlation of SR parameters measured in the medial gastrocnemius (MG) to muscle force in a cohort of young and senior subjects. STUDY TYPE: Prospective cohort study. SUBJECTS: Six young (26.1 ± 2.3 years) and six senior (76.7 ± 8.3 years) healthy females; two other subjects were scanned on three separate occasions for repeatability studies. FIELD STRENGTH/SEQUENCE: 1.5T using a single oblique sagittal slice with velocity-encoding in three directions (velocity-encoded phase contrast gradient echo sequence). ASSESSMENT: Age-related and regional differences in the SR eigenvalues (SRfiber , SRin-plane ), normal SRs (SRff , SRcc ), and shear SRs (SRfc , SRfc_max ) were statistically analyzed. STATISTICAL TESTS: Difference between young and senior cohorts were assessed using two-way analysis of variance (ANOVAs). The coefficient of variation and repeatability coefficient were calculated from repeat studies. Univariate and stepwise multivariable linear regression was performed to identify predictors of force. RESULTS: During isometric plantarflexion contraction, SRs in the principal basis (SRfiber , SRin-plane ) and maximum shear SR (SRfc_max ) was significantly lower in the senior cohort (P < 0.05). On multiple variable regression, maximum shear SR (SRfc_max ) and normal SR in the fiber cross-section (SRcc ) were significantly associated with force (R = 0.681, F = 14.034, P < 0.001). DATA CONCLUSION: This study establishes that computation of shear strain is feasible and is a significant predictor of force variability with age. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;47:1351-1357.

3D multimodal spatial fuzzy segmentation of intramuscular connective and adipose tissue from ultrashort TE MR images of calf muscle.

PURPOSE: To develop and evaluate an automated algorithm to segment intramuscular adipose (IMAT) and connective (IMCT) tissue from musculoskeletal MRI images acquired with a dual echo Ultrashort TE (UTE) sequence. THEORY AND METHODS: The dual echo images and calculated structure tensor images are the inputs to the multichannel fuzzy cluster mean (MCFCM) algorithm. Modifications to the basic multichannel fuzzy cluster mean include an adaptive spatial term and bias shading correction. The algorithm was tested on digital phantoms simulating IMAT/IMCT tissue under varying conditions of image noise and bias and on ten subjects with varying amounts of IMAT/IMCT. RESULTS: The MCFCM including the adaptive spatial term and bias shading correction performed better than the original MCFCM and adaptive spatial MCFCM algorithms. IMAT/IMCT was segmented from the unsmoothed simulated phantom data with a mean Dice coefficient of 0.933 ±0.001 when contrast-to-noise (CNR) was 140 and bias was varied between 30% and 65%. The algorithm yielded accurate in vivo segmentations of IMAT/IMCT with a mean Dice coefficient of 0.977 ±0.066. CONCLUSION: The proposed algorithm is completely automated and yielded accurate segmentation of intramuscular adipose and connective tissue in the digital phantom and in human calf data. Magn Reson Med 77:870-883, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

Does knee joint cooling change in vivo patellar tendon mechanical properties?

PURPOSE: This study aimed to assess the influence of knee joint cooling on the in vivo mechanical properties of the patellar tendon. METHODS: Twenty young, healthy women volunteered for the study. B-mode ultrasonography was used to record patellar tendon elongation during isometric ramp contraction of the knee extensors (5-7 s, 90° knee angle) and calculate tendon stiffness. Skin temperature was measured by infrared thermometry. Data were acquired before and after 30 min of local icing of the knee joint and compared by paired samples t-tests. RESULTS: After cold exposure, skin temperature as measured over the patellar tendon dropped by 16.8 ± 2.0 °C. Tendon stiffness increased from 2189 ± 551 to 2705 ± 902 N mm(-1) (+25 %, p = 0.007). Tendon strain decreased by 9 % (p = 0.004). A small, albeit significant reduction in maximum tendon force was observed (-3.3 %, p = 0.03). CONCLUSIONS: Knee cooling is associated with a significant increase in patellar tendon stiffness. The observed tendon stiffening may influence the operating range of sarcomeres, possibly limiting the maximal force generation capacity of knee extensor muscles. In addition, a stiffer tendon might benefit rate of force development, thus countering the loss in explosiveness typically described for cold muscles.

Effects of a multidisciplinary programme on postural stability in patients with chronic recurrent low back pain: preliminary findings.

PURPOSE: This longitudinal study investigated the effects of a multidisciplinary rehabilitation programme on postural stability in patients with low back pain. While the consequences of such rehabilitation programme have been described for pain, mobility, strength, and functional disability, the effects on postural stability have not been examined so far. METHODS: Thirty-four patients suffering from chronic low back pain were included to participate in a multidisciplinary rehabilitation programme. We assessed postural stability, pain, strength of the lumbar extensor muscles, and functional disability. The examinations were performed before the intervention, after 20 training sessions ("half-way point"), and at the end of the rehabilitation programme. RESULTS: All outcome measures improved significantly from baseline to the first follow-up evaluation and remained constant until completion of the rehabilitation programme. CONCLUSIONS: A multidisciplinary outpatient rehabilitation programme may improve postural stability, muscle strength, pain, and functional disability in patients with chronic low back pain.

Age-related differences in strain rate tensor of the medial gastrocnemius muscle during passive plantarflexion and active isometric contraction using velocity encoded MR imaging: potential index of lateral force transmission.

PURPOSE: The strain rate (SR) tensor measures the principal directions and magnitude of the instantaneous deformation; this study aims to track age-related changes in the 2D SR tensor in the medial gastrocnemius during passive joint rotation and active isometric contraction. METHODS: SR tensors were derived from velocity encoded magnetic resonance phase-contrast images in nine young (28 years) and eight senior (78 years) women. Strain rates along and in the cross-section of the fiber were calculated from the SR tensor and used to derive the out-plane SR. Age-related and regional differences in the SR eigenvalues, orientation, and the angle between the SR and muscle fiber (SR-fiber angle) were statistically analyzed. RESULTS: SR along the fiber was significantly different between the cohorts during isometric contraction with higher values in the young (P < 0.05). The SR-fiber angle was larger in the young for both motion types but this difference was not statistically significant. Significant regional differences in the SR indices was seen in passive joint rotation (P < 0.05) for both cohorts. CONCLUSION: SR mapping reflects age-related and regional differences during active and passive motion respectively; this may arise from differences in contractility (active motion) and elastic properties (active and passive motion).

Age-related differences in diffusion tensor indices and fiber architecture in the medial and lateral gastrocnemius.

PURPOSE: To investigate age related changes in diffusion tensor indices and fiber architecture of the medial and lateral gastrocnemius (MG and LG) muscles using diffusion tensor imaging (DTI). MATERIALS AND METHODS: The lower leg of five young and five senior subjects was scanned at 3 Tesla and DTI indices extracted using three methods: region of interest, histogram, and tract based. Tracked fibers were automatically edited to ensure physiologically relevant tracks. Pennation angles were measured with respect to the deep and superficial aponeuroses of both muscles. RESULTS: The three methods provided internally consistent measures of the DTI indices (correlation coefficient in the range of 0.90-0.99). The primary, secondary, and tertiary eigenvalues in the MG and LG increased significantly in the senior cohort (P < 0.05), while the small increase in fractional anisotropy with age was not significant (MG/LG: P = 0.39/0.85; 95% confidence interval: [-0.059/-0.056, 0.116/0.064]). Fiber lengths of MG fibers originating distally were significantly decreased in seniors (P < 0.05) while pennation angles decreased with age in the MG and LG but this was not significant. CONCLUSION: Fiber atrophy and increased fibrosis have opposing effects on the diffusion indices resulting in a complicated dependence with aging. Fiber architectural changes could play a role in determining aging muscle function.

Load-controlled moderate and high-intensity resistance training programs provoke similar strength gains in young women.

INTRODUCTION: While current exercise guidelines recommend progressive, high-intensity resistance training (RT) to promote muscle hypertrophy and strength gains, controversy exists regarding the efficacy of lighter-load RT. We compared 2 work-matched RT interventions that differed in training intensity. METHODS: Fifteen women underwent 10 weeks of unilateral knee extensor RT. One leg was trained at increasing intensity (intensity leg, InL, 50-80% 1-repetition maximum [1-RM]), and training progression in the contralateral leg (volume leg, VoL, 50% 1-RM) was based on increasing training volumes. Quadriceps muscle size (ultrasound, dual energy X-ray absorptiometry) and strength (isokinetic dynamometry) were assessed on 4 occasions. RESULTS: Both training programs induced significant, yet comparable increases in muscle size (InL: +4.6-12%, VoL: +3.1-11%) and strength (InL: +10-16%, VoL: +10-14%). CONCLUSIONS: Training at lower than commonly suggested intensities may be an equally effective alternative form of RT. Factors other than training intensity, such as the total mechanical work during training, may strongly affect the training response.