Patellofemoral pain (PFP) is one of the most common sports injuries of the knee joint and has a high persistence and recurrence rate. Medio-lateral patellar position in the knee extension position ...during contraction is associated with PFP. However, soft tissue tension that most influences the medio-lateral patellar position in the knee extension position during contraction in vivo is unclear. We aimed to clarify the relationship between medio-lateral patellar position and soft tissue tension around the knee joint. Twelve patients with PFP and 20 healthy participants were included. Medio-lateral patellar position and tension of the rectus femoris, vastus lateralis (VL), vastus medialis, iliotibial band (ITB), lateral patellofemoral ligament, and medial patellofemoral ligament were measured during contraction and rest. The tensions of the VL and ITB during contraction and the medio-lateral patellar position at rest were significantly associated with medio-lateral patellar position during contraction (β = 0.449, 0.354, and 0.393, respectively). In addition, the tension of ITB was significantly associated with the medio-lateral patellar position at rest (β = 0.646). These relationships were not affected by the presence of PFP. These findings suggest that the patellar position during contraction became more lateral as the tension in the VL and ITB increased, regardless of the presence of PFP. These results may facilitate the prevention and treatment of PFP.
The increasingly popular microbiopsy is an appealing alternative to the more invasive Bergström biopsy given the challenges associated with harvesting skeletal muscle in older populations. Parameters ...of muscle fiber morphology and composition derived from the microbiopsy have not been compared between young and older adults.
The purpose of this study was to examine muscle fiber morphology and composition in young (YM) and older (OM) males using the microbiopsy sampling technique. A secondary aim was to determine if specific strength is associated with serum levels of C-terminal agrin fragment CAF; an indicator of neuromuscular junction (NMJ) degradation.
Thirty healthy, YM (
= 15, age = 20.7 ± 2.2 years) and OM (
= 15, age = 71.6 ± 3.9 years) underwent ultrasound imaging to determine whole-muscle cross-sectional area (CSA) of the vastus lateralis and rectus femoris as well as isometric and isokinetic (60°⋅s
and 180°⋅s
) peak torque testing of the knee extensors. Microbiopsy samples of the vastus lateralis were collected from 13 YM and 11 OM, and immunofluorescence was used to calculate CSA and proportion of type I and type II fibers.
Peak torque was lower in OM at all velocities (
≤ 0.001;
= 1.39-1.86) but only lower at 180°⋅s
(
= 0.003;
= 1.23) when normalized to whole-muscle CSA. Whole-muscle CSA was smaller in OM (
= 0.001;
= 1.34), but atrophy was not present at the single fiber level (
> 0.05). Per individual, ∼900 fibers were analyzed, and type I fiber CSA was larger (
= 0.05;
= 0.94) in OM which resulted in a smaller type II/I fiber CSA ratio (
= 0.015;
= 0.95). CAF levels were not sensitive to age (
= 0.159;
= 0.53) nor associated with specific strength or whole-muscle CSA in OM.
The microbiopsy appears to be a viable alternative to the Bergström biopsy for histological analyses of skeletal muscle in older adults. NMJ integrity was not influential for age-related differences in specific strength in our healthy, non-sarcopenic older sample.
•The vastus lateralis free muscle flap as smart alternative for coverage of weight-bearing foot.•Skin-grafted muscle free flap for reconstruction of the weight-bearing foot using free muscle ...flaps.•Low donor-side morbidity after compartmental harvesting of the distal component of the vastus lateralis flap.
The lateral circumflex femoral artery one of the most favoured donor-site for a wide array of free flaps including either cutaneous, fascial and muscle components or a combination thereof. Here, we provide evidence on the safe use of the free vastus lateralis muscle flap and its feasibility for optimal soft tissue coverage of the weight-bearing foot.
Eighteen consecutive patients with soft tissue defects of the heel (n = 3, 16.6%) and plantar aspect of the mid- and forefoot (n = 15, 83.3%) of either post traumatic (n = 10), diabetic (n = 6) or ischemic (n = 2) etiology, received nineteen free vastus lateralis muscle free flaps covered with split-thickness skin grafts. The postoperative results in terms of wound healing, weight-bearing function, patient satisfaction were evaluated. In patients with chronic conditions (n = 8) the AOFAS (American Orthopaedic Foot and Ankle Society) scoring system was used preoperatively and 6 months postoperatively for evaluation of reconstruction outcomes.
All flaps survived. Their complete anatomical integration allowed regaining normal walking in all patients. In five patients, partial loss of the skin graft which either healed spontaneously or necessitated a redo skin grafting was noted. One patient developed a late flap-skin interface ulcer, which was solved by primary excision and direct closure. Compared with the preoperative values, the mean AOFAS score in the evaluated patients (n = 8) improved significantly (34.13 vs. 77.63, p < 0.001).
The skin-grafted free vastus lateralis muscle flap can safely be used as a “smart” tool for coverage of weight-bearing foot providing optimal cushioning and functional results without fearing donor-side morbidity.
Conchotome muscle biopsy is a type of muscle biopsy performed with cup forceps. Compared to open muscle biopsy, it has the advantages of being easier, less invasive, and safer, but its disadvantage ...is that the specimens obtained are smaller, which raises concerns about diagnostic accuracy. In our division, one of the authors, a rheumatologist, has performed conchotome muscle biopsy in a total of 7 cases of suspected polymyositis, dermatomyositis, and myositis as a partial manifestation of the disease since May 2019. All patients underwent MRI of both thighs prior to the examination, and the decision to biopsy from either the left or right vastus lateralis was based on the MRI findings. Pathological findings supporting the clinical diagnosis were obtained in 6 of the 7 patients. In all cases, no examination-related complications or postoperative complications occurred, and pain was mild. Traditionally, open muscle biopsy has been used for the pathological diagnosis of muscle diseases, but it requires special skill and only a limited number of medical institutions are able to perform it. In the pathological diagnosis of polymyositis and dermatomyositis, the diagnostic accuracy of conchotome muscle biopsy is not significantly inferior to that of open muscle biopsy, and it is sufficiently practical in situations where rapid diagnosis and treatment are needed with limited medical resources.
Anterolateral thigh (ALT) flaps has served as a workhorse in lower extremity reconstruction. Flap design showcases both fasciocutaneous (ALT-FC) and myocutaneous variants; the latter includes ...variable amounts of vastus lateralis muscle (ALT-VL). This study aims to evaluate outcomes of ALT flaps for lower extremity reconstruction at a Level 1 trauma center between ALT-FC and ALT-VL variants and assess if there is any added benefit of muscle in flap design.
A retrospective review was conducted at Los Angeles General Medical Center (2007–2022). Demographics, medical comorbidities, injury characteristics, and outcomes were collected. Outcomes included flap necrosis, postoperative infection, and ambulatory function.
Among 413 flaps placed, 63 were ALT flaps, of which 43 (68.3 %) were ALT-FC and 20 (31.7 %) were ALT-VL. Patient comorbidities, defect size, and wound severity were not significantly different across cohorts. Infectious and flap outcomes were comparable between cohorts, yet significantly more patients with hypertension and diabetes mellitus had osteomyelitis overall and in the ALT-FC cohort; patients with diabetes mellitus had significantly more flap complications. Flap survival was 96.8 % with 58.7 % of patients being fully ambulatory, without significance across degrees of ambulation or time to full ambulation.
Our findings demonstrated good outcomes with low rates of infection and flap loss that were comparable between both ALT-FC and ALT-VL cohorts. ALT-FC has recently been favored given decreased donor site morbidity without impaired function or infectious/flap complications. Accordingly, our findings may suggest that the addition of muscle to flap design may not be necessary for successful reconstruction.
•The anterolateral thigh flap is a workhorse for distal third-leg reconstruction.•Flap design showcases both fasciocutaneous and myocutaneous variants.•Both options demonstrated excellent flap survival and low infection rates.•However, the fasciocutaneous option offers minimal donor-site morbidity.
Key points
Muscle glycogen and intramuscular triglycerides (IMTG, stored in lipid droplets) are important energy substrates during prolonged exercise.
Exercise‐induced changes in lipid droplet (LD) ...morphology (i.e. LD size and number) have not yet been studied under nutritional conditions typically adopted by elite endurance athletes, that is, after carbohydrate (CHO) loading and CHO feeding during exercise.
We report for the first time that exercise reduces IMTG content in both central and peripheral regions of type I and IIa fibres, reflective of decreased LD number in both fibre types whereas reductions in LD size were exclusive to type I fibres.
Additionally, CHO feeding does not alter subcellular IMTG utilisation, LD morphology or muscle glycogen utilisation in type I or IIa/II fibres.
In the absence of alterations to muscle fuel selection, CHO feeding does not attenuate cell signalling pathways with regulatory roles in mitochondrial biogenesis.
We examined the effects of carbohydrate (CHO) feeding on lipid droplet (LD) morphology, muscle glycogen utilisation and exercise‐induced skeletal muscle cell signalling. After a 36 h CHO loading protocol and pre‐exercise meal (12 and 2 g kg–1, respectively), eight trained males ingested 0, 45 or 90 g CHO h–1 during 180 min cycling at lactate threshold followed by an exercise capacity test (150% lactate threshold). Muscle biopsies were obtained pre‐ and post‐completion of submaximal exercise. Exercise decreased (P < 0.01) glycogen concentration to comparable levels (∼700 to 250 mmol kg–1 DW), though utilisation was greater in type I (∼40%) versus type II fibres (∼10%) (P < 0.01). LD content decreased in type I (∼50%) and type IIa fibres (∼30%) (P < 0.01), with greater utilisation in type I fibres (P < 0.01). CHO feeding did not affect glycogen or IMTG utilisation in type I or II fibres (all P > 0.05). Exercise decreased LD number within central and peripheral regions of both type I and IIa fibres, though reduced LD size was exclusive to type I fibres. Exercise induced (all P < 0.05) comparable AMPKThr172 (∼4‐fold), p53Ser15 (∼2‐fold) and CaMKIIThr268 phosphorylation (∼2‐fold) with no effects of CHO feeding (all P > 0.05). CHO increased exercise capacity where 90 g h–1 (233 ± 133 s) > 45 g h–1 (156 ± 66 s; P = 0.06) > 0 g h–1 (108 ± 54 s; P = 0.03). In conditions of high pre‐exercise CHO availability, we conclude CHO feeding does not influence exercise‐induced changes in LD morphology, glycogen utilisation or cell signalling pathways with regulatory roles in mitochondrial biogenesis.
Key points
Muscle glycogen and intramuscular triglycerides (IMTG, stored in lipid droplets) are important energy substrates during prolonged exercise.
Exercise‐induced changes in lipid droplet (LD) morphology (i.e. LD size and number) have not yet been studied under nutritional conditions typically adopted by elite endurance athletes, that is, after carbohydrate (CHO) loading and CHO feeding during exercise.
We report for the first time that exercise reduces IMTG content in both central and peripheral regions of type I and IIa fibres, reflective of decreased LD number in both fibre types whereas reductions in LD size were exclusive to type I fibres.
Additionally, CHO feeding does not alter subcellular IMTG utilisation, LD morphology or muscle glycogen utilisation in type I or IIa/II fibres.
In the absence of alterations to muscle fuel selection, CHO feeding does not attenuate cell signalling pathways with regulatory roles in mitochondrial biogenesis.
The diagnostic accuracy of tensiomyography (TMG) parameters compared to the gold standard in neuromuscular fatigue evaluation using voluntary and electrically induced muscle activation is unclear. ...This study aimed to investigate the diagnostic accuracy of TMG parameters to detect individual changes after interventions that were designed to induce central or peripheral fatigue. Nineteen males (age: 32.2 ± 9.3 years) performed two interventions, consisting of maintaining 25% of maximal voluntary contraction (MViC25%) and a 30 s all-out cycling test (Wingate), respectively. TMG parameters, maximum voluntary contraction (PtMViC), voluntary activation (VA%) and electrically elicited double twitches (Dtw) were assessed on the knee extensors before (PRE), one minute (POST) and seven minutes after (POST7) the intervention. The diagnostic accuracy (AUC) of TMG parameters were evaluated in comparison to two criteria measures (PtMViC and Dtw). RM ANOVA revealed a significant interaction between the effects of intervention and time on VA% (p = 0.001) and Dtw (p < 0.001) but not for PtMViC (p = 0.420). AUC showed that TMG parameters had a good ability in detecting muscular fatigue assessed by Dtw but not by PtMViC. The results of the current study suggest that TMG parameters can be used to monitor peripheral neuromuscular fatigue.
Coratella, G, Beato, M, Bertinato, L, Milanese, C, Venturelli, M, and Schena, F. Including the eccentric phase in resistance training to counteract the effects of detraining in women: a randomized ...controlled trial. J Strength Cond Res 36(11): 3023-3031, 2022-The current study compared the effects of concentric-based (CONC), eccentric-based (ECC), and traditional concentric-eccentric (TRAD) resistance training on muscle strength, mass, and architecture and the postdetraining retention of the training-induced effects in women. Sixty women were randomly assigned to unilateral volume-equated CONC, ECC, or TRAD knee extension training or control ( N = 15 per group). Before training, after an 8-week intervention period, and after an 8-week detraining period, isokinetic concentric, eccentric, and isometric torque were measured. In addition, thigh lean mass was assessed by dual X-ray absorptiometry and vastus lateralis thickness, pennation angle, and fascicle length by ultrasound. After training, concentric and isometric torque increased ( p < 0.05) similarly in all groups, whereas eccentric torque increased more in ECC than that in CONC (+13.1%, effect size (ES): 0.71 0.04-1.38) and TRAD (+12.6%, ES: 0.60 0.12-1.08). Thigh lean mass increased in ECC (+6.1%, ES: 0.47 0.27-0.67) and TRAD (+3.1%, ES: 0.33 0.01-0.65). Vastus lateralis thickness and pennation angle increased ( p < 0.05) similarly in all groups, whereas fascicle elongation was visible in ECC (+9.7%, ES: 0.92 0.14-1.65) and TRAD (+7.1%, ES: 0.64 0.03-1.25). After detraining, all groups retained ( p < 0.05) similar concentric torque. ECC and TRAD preserved eccentric torque ( p < 0.05), but ECC more than TRAD (+17.9%, ES: 0.61 0.21-1.21). All groups preserved isometric torque ( p < 0.05), but ECC more than CONC (+14.2%, ES: 0.71 0.04-1.38) and TRAD (+13.8%, ES: 0.65 0.10-1.20). Thigh lean mass and vastus lateralis fascicle length were retained only in ECC ( p < 0.05), pennation angle was preserved in all groups ( p < 0.05), and thickness was retained in CONC and ECC ( p < 0.05). Including the eccentric phase in resistance training is essential to preserve adaptations after detraining.
. Threshold determination for improving training and sports performance is important for researchers and trainers, who currently use different methods for determining lactate, ventilatory or muscle ...oxygenation (SmO
) thresholds. Our study aimed to compare the identification of the intensity at the first and second thresholds using lactate and SmO
data by different mathematical methods in different muscles during a graded cycling test.
. Twenty-six cyclists (15 males and 11 females; 23 ±6 years, 1.71 ± 0.09 m, 64.3 ± 8.8 Kg and 12 ± 3 training hours per week) performed a graded test on the cycle ergometer. Power output and saturation of muscle oxygen in four muscles (vastus lateralis, biceps femoris, gastrocnemius and tibialis anterior) were measured, along with systemic lactate concentration.
. Our results showed that any method was reliable for determining the first muscle oxygenation threshold (MOT1) when comparing the lactate threshold in any muscle. However, the best method for determining the second muscle oxygenation threshold (MOT2) was the Exp-Dmax (
< 0.01; ICC = 0.79-0.91) in all muscles. In particular, the vastus lateralis muscle showed the highest intraclass correlation coefficient (ICC = 0.91, CI95% 0.81, 0.96). However, results varied per sex across all muscles analyzed.
. Although the first muscle oxygenation threshold could not be determined using mathematical methods in all the muscles analyzed, the Exp-Dmax method presented excellent results in detecting the second systemic threshold in the vastus lateralis.
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