Quadriceps Cross-sectional Area Research Articles

Blood Flow Restriction Does Not Promote Additional Effects on Muscle Adaptations When Combined With High-Load Resistance Training Regardless of Blood Flow Restriction Protocol.

Teixeira, EL, Ugrinowitsch, C, de Salles Painelli, V, Silva-Batista, C, Aihara, AY, Cardoso, FN, Roschel, H, and Tricoli, V. Blood flow restriction does not promote additional effects on muscle adaptations when combined with high-load resistance training regardless of blood flow restriction protocol. J Strength Cond Res 35(5): 1194-1200, 2021-The aim of this study was to investigate, during high-load resistance training (HL-RT), the effect of blood flow restriction (BFR) applied during rest intervals (BFR-I) and muscle contractions (BFR-C) compared with HL-RT alone (no BFR), on maximum voluntary isometric contraction (MVIC), maximum dynamic strength (one repetition maximum [1RM]), quadriceps cross-sectional area (QCSA), blood lactate concentration ([La]), and root mean square of the surface electromyography (RMS-EMG) responses. Forty-nine healthy and untrained men (25 ± 6.2 years, 178.1 ± 5.3 cm and 78.8 ± 11.6 kg) trained twice per week, for 8 weeks. One leg of each subject performed HL-RT without BFR (HL-RT), whereas the contralateral leg was randomly allocated to 1 of 2 unilateral knee extension protocols: BFR-I or BFR-C (for all protocols, 3 × 8 repetitions, 70% 1RM). Maximum voluntary isometric contraction, 1RM, QCSA, and acute changes in [La] and RMS-EMG were assessed before and after training. The measurement of [La] and RMS-EMG was performed during the control sessions with the same relative load obtained after the 1RM test, before and after training. Similar increases in MVIC, 1RM, and QCSA were demonstrated among all conditions, with no significant difference between them. [La] increased for all protocols in pre-training and post-training, but it was higher for BFR-I compared with the remaining protocols. Increases in RMS-EMG occurred for all protocols in pre-training and post-training, with no significant difference between them. In conclusion, despite of a greater metabolic stress, BFR inclusion to HL-RT during rest intervals or muscle contraction did not promote any additive effect on muscle strength and hypertrophy.

High-Intensity Interval Aerobic Work for Strength Athletes with Arterial Hypertension: A Randomized Controlled Trial

Hypertension is often diagnosed in strength athletes of heavyweight categories. A study was made to assess how high-intensity aerobic work affects the body composition, blood pressure (BP), oxidative capacity, and working muscle hypertrophy and strength in strength athletes with arterial hypertension. Examination and physical rehabilitation were performed in 55 hypertensive heavyweight strength athletes comparable in age, gender, and main clinical manifestations. The athletes were randomized into two groups, a test group (n = 35) and a control group (n = 20). The test-group athletes trained on a bicycle ergometer according to a high-intensity interval protocol 3 times a week for 120 days, and the control-group athletes trained according to their conventional power protocol 3 times a week for 120 days. The study methods included interrogation, physical examination, triplicate BP measurement, bioimpedance analysis with calculation of body composition indices, ergospirometry, measurement of the oxygenation level of muscle tissue, ultrasonographic measurements of the anatomical cross-sectional area (CSA) of the quadriceps femoris, evaluation of the maximal voluntary contraction strength of the quadriceps femoris, and methods of mathematical statistics. After 120 days of training, the athletes of the test group displayed a 72% decrease in oxygenation, an increase in power and working time at the level of maximum oxygen consumption, and an increase in quadriceps femoris CSA. BP decreased significantly in the group: systolic BP (SBP), by 4.7% and diastolic BP (DBP), by 5.6%. The physical rehabilitation protocol developed for strength athletes makes it possible to effectively and safely affect the body composition, hypertrophy, oxidative capacity of working muscles, and BP.

Optimal parameters of blood flow restriction and resistance training on quadriceps strength and cross-sectional area and pain in knee osteoarthritis

BACKGROUND: Knee osteoarthritis (KOA) is one of the most common chronic diseases impacting millions of elderly people. OBJECTIVES: The study compared the effects of two intensities of partial blood flow restriction (BFR) with low-intensity resistance training on quadriceps strength and cross-sectional area (CSA), and pain in people with knee osteoarthritis (PwKOA). METHODS: Thirty-five PwKOA, aged 50–65, participated. Quadriceps CSA was measured by ultrasonography, quadriceps strength – by isokinetic dynamometry and pain by VAS. These outcome variables were obtained at the beginning of the study and re-evaluated eight weeks after the intervention. RESULTS: An interaction effect was present for quadriceps CSA (P= 0.042) and quadriceps strength (P= 0.006), showing that using 70% of total occlusion pressure with 30% 1RM had a more significant effect. Knee pain improved significantly through the main effect of BFR (P< 0.001), and low-intensity resistance training (P= 0.011). Pain improved more at 70% of total occlusion pressure, with 30% of 1RM (2.5 ± 1.06) than 50% total occlusion pressure with 10% of 1RM (5.77 ± 1.46). CONCLUSION: A combination of 70% of total occlusion pressure with 30% 1RM could be beneficial in PwKOA in improving pain, and increasing the quadriceps strength. The changes in the quadriceps strength could be a predictor for knee pain.

Comparison of Blood Flow Restriction Training versus Non-Occlusive Training in Patients with Anterior Cruciate Ligament Reconstruction or Knee Osteoarthritis: A Systematic Review.

Patients undergoing anterior cruciate ligament (ACL) reconstruction and patients suffering from knee osteoarthritis (KOA) have been shown to have quadriceps muscle weakness and/or atrophy in common. The physiological mechanisms of blood flow restriction (BFR) training could facilitate muscle hypertrophy. The purpose of this systematic review is to investigate the effects of BFR training on quadriceps cross-sectional area (CSA), pain perception, function and quality of life on these patients compared to a non-BFR training. A literature research was performed using Web of Science, PEDro, Scopus, MEDLINE, Dialnet, CINAHL and The Cochrane Library databases. The main inclusion criteria were that papers were English or Spanish language reports of randomized controlled trials involving patients with ACL reconstruction or suffering from KOA. The initial research identified 159 publications from all databases; 10 articles were finally included. The search was conducted from April to June 2020. Four of these studies found a significant improvement in strength. A significant increase in CSA was found in two studies. Pain significantly improved in four studies and only one study showed a significant improvement in functionality/quality of life. Low-load training with BFR may be an effective option treatment for increasing quadriceps strength and CSA, but more research is needed.

The effect of short-term exercise prehabilitation on skeletal muscle protein synthesis and atrophy during bed rest in older men.

BackgroundPoor recovery from periods of disuse accelerates age‐related muscle loss, predisposing individuals to the development of secondary adverse health outcomes. Exercise prior to disuse (prehabilitation) may prevent muscle deterioration during subsequent unloading. The present study aimed to investigate the effect of short‐term resistance exercise training (RET) prehabilitation on muscle morphology and regulatory mechanisms during 5 days of bed rest in older men.MethodsTen healthy older men aged 65–80 years underwent four bouts of high‐volume unilateral leg RET over 7 days prior to 5 days of inpatient bed rest. Physical activity and step‐count were monitored over the course of RET prehabilitation and bed rest, whilst dietary intake was recorded throughout. Prior to and following bed rest, quadriceps cross‐sectional area (CSA), and hormone/lipid profiles were determined. Serial muscle biopsies and dual‐stable isotope tracers were used to determine integrated myofibrillar protein synthesis (iMyoPS) over RET prehabilitation and bed rest phases, and acute postabsorptive and postprandial myofibrillar protein synthesis (aMyoPS) rates at the end of bed rest.ResultsDuring bed rest, daily step‐count and light and moderate physical activity time decreased, whilst sedentary time increased when compared with habitual levels (P < 0.001 for all). Dietary protein and fibre intake during bed rest were lower than habitual values (P < 0.01 for both). iMyoPS rates were significantly greater in the exercised leg (EX) compared with the non‐exercised control leg (CTL) over prehabilitation (1.76 ± 0.37%/day vs. 1.36 ± 0.18%/day, respectively; P = 0.007). iMyoPS rates decreased similarly in EX and CTL during bed rest (CTL, 1.07 ± 0.22%/day; EX, 1.30 ± 0.38%/day; P = 0.037 and 0.002, respectively). Postprandial aMyoPS rates increased above postabsorptive values in EX only (P = 0.018), with no difference in delta postprandial aMyoPS stimulation between legs. Quadriceps CSA at 40%, 60%, and 80% of muscle length decreased significantly in EX and CTL over bed rest (0.69%, 3.5%, and 2.8%, respectively; P < 0.01 for all), with no differences between legs. No differences in fibre‐type CSA were observed between legs or with bed rest. Plasma insulin and serum lipids did not change with bed rest.ConclusionsShort‐term resistance exercise prehabilitation augmented iMyoPS rates in older men but did not offset the relative decline in iMyoPS and muscle mass during bed rest.

Sex-Dependent Effects of Quadriceps Fat Content on Single Muscle Fiber Size in Older Adults

Evidence suggests that ectopic fat deposition interferes with skeletal muscle structure and function, but few studies have examined underlying morphological and contractile properties at the single fiber level. Healthy older (65-75 y) men (n=9) and women (n=9) underwent dynamometry for assessment of knee extensor maximal torque, water-fat magnetic resonance imaging to quantify quadriceps muscle cross-sectional area (CSA) and fat fraction (FF), and vastus lateralis biopsies to determine morphology and function of type I and II muscle fibers. Despite similar body mass indices (24.4±1.3 vs. 24.6±0.5 kg∙m2, p=0.93) and daily moderate-to-vigorous physical activity (46±7 vs. 41±9 min∙d-1, p=0.67), women had greater FF (9.0±0.3 [range: 7.6-10.6] vs. 7.9±0.4 [6.0-9.7] %, p=0.04) than men, indicating increased adipose tissue deposition in skeletal muscle. Women also had smaller quadriceps CSA (39.8±1.8 vs. 57.9±1.3 cm2, p=0.01), specific torque (1.5±0.1 vs. 1.9±0.1 Nm∙cm-2, p=0.01) and type II fiber CSA (3,943±312 [2,350-5,140] vs. 5,352±384 [3,560-6,590] µm2, p=0.01) than men. Type I CSA did not differ by sex (4,918±228 [3,740-5,600] vs. 5,630±440 [3,640-7,670] µm2, p=0.19). In older women, FF was inversely associated with single fiber CSA in type I (r= -0.81, p=0.02) and II (r= -0.76, p=0.03) fibers, and tended to be associated with slower myosin-actin cross-bridge kinetics (longer myosin attachment time) in type I fibers (r=0.65, p=0.08). These relationships were not observed in men. Overall, healthy older women have greater intramuscular fat than men, which may contribute to sex-specific effects on knee extensor specific torque through differences in muscle fiber size and cross-bridge kinetics.

Perceptual and Neuromuscular Responses Adapt Similarly Between High-Load Resistance Training and Low-Load Resistance Training With Blood Flow Restriction.

Teixeira, EL, Painelli, VdS, Schoenfeld, BJ, Silva-Batista, C, Longo, AR, Aihara, AY, Cardoso, FN, Peres, BdA, and Tricoli, V. Perceptual and neuromuscular responses adapt similarly between high-load resistance training and low-load resistance training with blood flow restriction. J Strength Cond Res 36(9): 2410-2416, 2022-This study compared the effects of 8 weeks of low-load resistance training with blood flow restriction (LL-BFR) and high-load resistance training (HL-RT) on perceptual responses (rating of perceived exertion [RPE] and pain), quadriceps cross-sectional area (QCSA), and muscle strength (1 repetition maximum [RM]). Sixteen physically active men trained twice per week, for 8 weeks. One leg performed LL-BFR (3 sets of 15 repetitions, 20% 1RM), whereas the contralateral leg performed HL-RT (3 sets of 8 repetitions, 70% 1RM). Rating of perceived exertion and pain were evaluated immediately after the first and last training sessions, whereas QCSA and 1RM were assessed at baseline and after training. Rating of perceived exertion was significantly lower (6.8 ± 1.1 vs. 8.1 ± 0.8, p = 0.001) and pain significantly higher (7.1 ± 1.2 vs. 5.8 ± 1.8, p = 0.02) for LL-BFR than that for HL-RT before training. Significant reductions in RPE and pain were shown for both protocols after training (both p < 0.0001), although no between-protocol differences were shown in absolute changes ( p = 0.10 and p = 0.48, respectively). Both LL-BFR and HL-RT were similarly effective in increasing QCSA (7.0 ± 3.8% and 6.3 ± 4.1%, respectively; both p < 0.0001) and 1RM (6.9 ± 4.1% and 13.7 ± 5.9%, respectively; both P < 0.0001), although absolute changes for 1RM in HL-RT were greater than LL-BFR ( p = 0.001). In conclusion, LL-BFR produces lower RPE values and a higher pain perception than HL-RT. However, consistent application of these approaches result in chronic adaptations so that there are no differences in perceptual responses over the course of time. In addition, muscle strength is optimized with HL-RT despite similar increases in muscle hypertrophy between conditions.

Neuromuscular electrical stimulation in early rehabilitation of patients with postoperative complications after cardiovascular surgery: A randomized controlled trial.

Background:To evaluate the effectiveness of neuromuscular electrical stimulation (NMES) in early rehabilitation of patients with postoperative complications after cardiovascular surgery.Methods:37 patients (25 men and 12 women) aged 45 to 70 years with postoperative complications after cardiovascular surgery were included in the study. Eighteen patients underwent NMES daily since postoperative day 3 until discharge in addition to standard rehabilitation program (NMES group), and 19 patients underwent standard rehabilitation program only (non-NMES group). The primary outcome was the knee extensors strength at discharge in NMES group and in control. Secondary outcomes were the handgrip strength, knee flexor strength, and cross-sectional area (CSA) of the quadriceps femoris in groups at discharge.Results:Baseline characteristics were not different between the groups. Knee extensors strength at discharge was significantly higher in the NMES group (28.1 [23.8; 36.2] kg on the right and 27.45 [22.3; 33.1] kg on the left) than in the non-NMES group (22.3 [20.1; 27.1] and 22.5 [20.1; 25.9] kg, respectively; P < .001). Handgrip strength, knee flexor strength, quadriceps CSA, and 6 minute walk distance at discharge in the groups had no significant difference.Conclusions:This pilot study shows a beneficial effect of NMES on muscle strength in patients with complications after cardiovascular surgery. The use of NMES showed no effect on strength of non-stimulated muscle, quadriceps CSA, and distance of 6-minute walk test at discharge.Further blind randomized controlled trials should be performed with emphasis on the effectiveness of NEMS in increasing muscle strength and structure in these patients.

Are muscle fibres of body builders intrinsically weaker? A comparison with single fibres of aged-matched controls.

Skeletal muscles of Body Builders (BB) represent an interesting model to study muscle mass gains in response to high volume resistance training. It is debated whether muscle contractile performance improves in proportion to mass. Here, we aim to assess whether muscle hypertrophy does not occur at the expense of performance. Six BB and Six untrained controls (CTRL) were recruited. Cross-sectional area (CSA) and maximum voluntary contraction (MVC) of quadriceps femoris muscle (QF) and CSA and architecture of vastus lateralis (VL) were determined. Moreover, a biopsy was taken from VL mid-portion and single fibres were analysed. QF CSA and MVC were 32% (n.s., P=.052) and 58% (P=.009) higher in BB than in CTRL, respectively. VL CSA was 37% higher in BB (P=.030). Fast 2A fibres CSA was 24% (P=.048) greater in BB than in CTRL, when determined in immunostained sections of biopsy samples. Single permeabilized fast fibres CSA was 37% (n.s., P=.052) higher in BB than in CTRL, and their force was slightly higher in BB (n.s.), while specific tension (P0 ) was 19% (P=.024) lower. The lower P0 was not explained either by lower myosin content or by impaired calcium diffusion. Conversely, the swelling caused by skinning-induced permeabilization was different and, when used to correct P0 , differences between populations disappeared. The results show that high degree of muscle hypertrophy is not detrimental for force generation capacity, as increases in fibre size and force are strictly proportional once the differential swelling response is accounted for.

A 4-week exercise and protein program improves muscle mass and physical functioning in older adults - A pilot study.

Prehabilitation might attenuate common surgery-induced losses in muscle mass and physical performance. Beneficial effects of physical exercise with protein supplementation have been reported in older adults, but typically after an intervention of at least 12weeks. The time-window for pre-surgery training is often limited to around 30days, and it is not known if it is possible to achieve comparable results in such a short time window. The aim of this study was to pilot-test the effectiveness of a controlled four-week combined exercise and protein supplementation program on skeletal muscle-related outcomes in a Dutch older adult population. This study was a one-armed pilot trial. Seventeen older men and women, aged 55-75y, not scheduled for surgery. A 4-week intervention program consisting of a twice-weekly supervised resistance and high-intensity aerobic exercise training of 75min, combined with daily protein supplementation (2 doses of 15.5g/day at breakfast and lunch). After two and four weeks, isometric quadriceps maximal voluntary contraction (MVC) was assessed via Biodex and quadriceps cross-sectional area (CSA) via magnetic resonance imaging. Other outcome measures were handgrip strength, chair rise time and maximal aerobic capacity (VO2-max), as assessed from a submaximal exercise test. Compliance to the supervised training sessions (99.3%) and the protein supplementation (97%) was very high. The 4-week exercise and protein program led to an increase in quadriceps CSA of 2.3±0.7cm2 (P=0.008) in the dominant leg and 3.2±0.7cm2 (P<0.001) in the non-dominant leg. Isometric quadriceps MVC increased in the dominant leg (Δ14±4Nm, P=0.001) and in the non-dominant leg (Δ17±5Nm, P=0.003). Chair rise test time improved with -3.8±0.5s (P<0.0001), and VO2-max improved with 3.3±1.1ml/min/kg (P=0.014). We observed no changes in body weight and handgrip strength. A 4-week exercise and protein intervention led to improvements in muscle-related outcomes in older adults with low levels of physical activity.

Diagnostic and clinical values of non-cardiac ultrasound in COPD: A systematic review

BackgroundClinical and research utility of non-cardiac ultrasound (US) in chronic obstructive pulmonary disease (COPD) has been widely investigated. However, there is no systematic review assessing the clinical values of non-cardiac...

Volume Load Rather Than Resting Interval Influences Muscle Hypertrophy During High-Intensity Resistance Training.

Longo, AR, Silva-Batista, C, Pedroso, K, de Salles Painelli, V, Lasevicius, T, Schoenfeld, BJ, Aihara, AY, de Almeida Peres, B, Tricoli, V, and Teixeira, EL. Volume load rather than resting interval influences muscle hypertrophy during high-intensity resistance training. J Strength Cond Res 36(6): 1554-1559, 2022-Interset rest interval has been proposed as an important variable for inducing muscle mass and strength increases during resistance training. However, its influence remains unclear, especially when protocols with differing intervals have equalized volume. We aimed to compare the effects of long (LI) vs. short rest interval (SI) on muscle strength (one repetition maximum [1RM]) and quadriceps cross-sectional area (QCSA), with or without equalized volume load (VL). Twenty-eight subjects trained twice a week for 10 weeks. Each subject's leg was allocated to 1 of 4 unilateral knee extension protocols: LI, SI, SI with VL -matched by LI (VLI-SI), and LI with VL-matched by SI (VSI-LI). A 3-minute rest interval was afforded in LI and VSI-LI protocols, while SI and VLI-SI employed a 1-minute interval. All subjects trained with a load corresponding to 80% 1RM. One repetition maximum and QCSA were measured before and after training. All protocols significantly increased 1RM values in post-training (p < 0.0001; LI: 27.6%, effect size [ES] = 0.90; VLI-SI: 31.1%, ES = 1.00; SI: 26.5%, ES = 1.11; and VSI-LI: 31.2%, ES = 1.28), with no significant differences between protocols. Quadriceps cross-sectional area increased significantly for all protocols in post-training (p < 0.0001). However, absolute changes in QCSA were significantly greater in LI and VLI-SI (13.1%, ES: 0.66 and 12.9%, ES: 0.63) than SI and VSI-LI (6.8%, ES: 0.38 and 6.6%, ES: 0.37) (both comparisons, p < 0.05). These data suggest that maintenance of high loads is more important for strength increases, while a greater VL plays a primary role for hypertrophy, regardless of interset rest interval.

Perioperative and Postoperative Factors Influence Quadriceps Atrophy and Strength After ACL Reconstruction: A Systematic Review.

Background:Quadriceps dysfunction after anterior cruciate ligament (ACL) reconstruction is common and may affect return to sport due to resulting muscle atrophy and muscle weakness.Purpose:To systematically review the available literature regarding the impact of perioperative and postoperative interventions on quadriceps atrophy and loss of strength after ACL reconstruction.Study Design:Systematic review; Level of evidence, 3.Methods:A systematic review was performed in accordance with the 2009 PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines using PubMed, CINAHL, Cochrane Central, and Embase. The quality of evidence was evaluated using the Modified Coleman Methodology Score to determine consensus scores. Eligible level 1 or level 2 studies included interventions of perioperative nerve block, intraoperative tourniquet use, postoperative nutritional supplementation, and postoperative blood flow restriction training. Additionally, the included studies quantified postoperative quadriceps measurements such as thigh circumference, quadriceps cross-sectional area (CSA), isokinetic quadriceps strength, and/or quadriceps electromyographic (EMG) testing.Results:In total, 15 studies met stated inclusion and exclusion criteria with the following intervention types: perioperative nerve block (n = 4), intraoperative tourniquet use (n = 5), postoperative nutritional supplementation (n = 3), and postoperative blood flow restriction (n = 3). Intraoperative tourniquet use resulted in decreased thigh circumference and detrimental EMG changes in quadriceps function in 3 of the 5 included studies. Perioperative femoral nerve blocks were associated with transient decreases in postoperative quadriceps strength, persisting up to 6 weeks after surgery, in 2 of the 4 studies. Postoperative blood flow restriction training augmented quadriceps size and function after ACL reconstruction in 2 of 3 studies. Postoperative nutritional supplementation was associated with increased quadriceps volume and strength in 1 of the 3 studies examined.Conclusion:The peri- and postoperative factors reviewed here may influence quadriceps atrophy and strength after ACL reconstruction. Our results tentatively indicated that blood flow restriction training may be beneficial to the quadriceps after ACL reconstruction and that intraoperative tourniquet use and nerve block administration may be detrimental; however, the strongest finding was that all of these interventions would benefit from further level 1 and 2 evidence studies, including multicenter, randomized controlled trials with extended follow-up, to definitively determine their impact on return to activity.

Low-Load Resistance Training With Blood-Flow Restriction in Relation to Muscle Function, Mass, and Functionality in Women With Rheumatoid Arthritis.

To evaluate the effects of a low-load resistance training program associated with partial blood-flow restriction in patients with rheumatoid arthritis (RA). Forty-eight women with RA were randomized into 1 of 3 groups: high-load resistance training (HL-RT; 70% 1 repetition maximum [1RM]), low-load resistance training (30% 1RM) with partial blood-flow restriction training (BFRT), and a control group. Patients completed a 12-week supervised training program and were assessed for lower-extremity 1RM, quadriceps cross-sectional area (CSA), physical function (timed-stands test [TST], timed-up-and-go test [TUG], and Health Assessment Questionnaire [HAQ]), and quality of life (Short Form 36 health survey [SF-36]) at baseline and after the intervention. BFRT and HL-RT were similarly effective in increasing maximum dynamic strength in both leg press (22.8% and 24.2%, respectively; P < 0.0001 for all) and knee extension (19.7% and 23.8%, respectively; P < 0.0001 for all). Quadriceps CSA was also significantly increased in both BFRT and HL-RT (9.5% and 10.8%, respectively; P < 0.0001 for all). Comparable improvements in TST (11.2% and 14.7%; P < 0.0001 for all) and TUG (-6.8% [P < 0.0053] and -8.7% [P < 0.0001]) were also observed in BFRT and HL-RT, respectively. Improvements in both groups were significantly greater than those of the control group (P < 0.05 for all). SF-36 role physical and bodily pain and HAQ scores were improved only in BFRT (45.7%, 22.5%, and -55.9%, respectively; P < 0.05 for all). HL-RT resulted in 1 case of withdrawal and several cases of exercise-induced pain, which did not occur in BFRT. BFRT was effective in improving muscle strength, mass, function, and health-related quality of life in patients with RA, emerging as a viable therapeutic modality in RA management.

Intra- and inter-muscular differences in the cross-sectional area of the quadriceps muscles assessed by extended field-of-view ultrasonography.

Τo examine the inter- and intra-muscular differences in the anatomical cross-sectional area (CSA) of the quadricep muscles, using extended - field of view (EFOV) ultrasonography (US). Panoramic transverse US images of the thigh were acquired from 10 young participants at five different locations across the thigh, in two sessions, spaced a week apart. The CSA of the vastus medialis (VM), rectus femoris (RF), vastus intermedius (VI), vastus lateralis (VL) and tensor vastus intermedius (TVI) was quantified. The intraclass correlation coefficients ranged from 0.75 to 0.97 and the standard error of measurement ranged from 0.78% to 6.61%, indicating high test-retest reliability. Analysis of the variance indicated that among the 5 quadriceps muscles the VL and the RF displayed the greater CSA proximally, the VI medially and the VM distally across the thigh (p <0.05). No differences in the quadriceps CSA measured with and without including the TVI were found (p >0.05). The EFOV US technique provides transverse scans of the quadriceps muscle in vivo and allowed a reliable and non-invasive determination of CSA at a low cost. Evaluation of CSA along the thigh largely depends on the measurement site. Future studies that examine the quadriceps CSA using EFOV after any form of intervention should consider changes of at least 6.5% as meaningful.

Long-lasting unilateral muscle wasting and weakness following injury and immobilisation

Quadriceps strength and size was measured in a small group of subjects (n = 7) 1 to 5 years after full mobilisation following some form of unilateral lower limb trauma. The mean maximum voluntary isometric force (MVC) was significantly lower for the injured (I) compared to the uninjured (UI) leg (369 N +/- 139 vs. 535 N +/- 131, p less than 0.01). Electrical stimulation superimposed on the voluntary contractions demonstrated that all subjects were able to maximally activate the quadriceps of both legs. Mean quadriceps cross-sectional area (CSA) was significantly lower in the I (64 cm2 +/- 12.8) compared to the UI leg (80 +/- 12.8, p less than 0.01). One subject with marked unilateral weakness and wasting took part in a 3-month strength training study for the injured leg. After training the I/UI ratio had been restored to nearly 100% (94% MVC; 88% CSA). These results would suggest that longer and more intensive physiotherapy is required in the immediate post-injury period to restore muscle strength and size to severely atrophied muscle.

Chronic Resistance Exercise Improves Functioning and Reduces Toll-Like Receptor Signaling in Elderly Patients With Postoperative Deconditioning

ObjectiveElderly patients continue to experience low levels of mobility during and following postoperative hospitalization that lead to persistent physical decline. Therefore, here we compared chronic resistance (CR) exercise against chronic aerobic (CA) exercise in ameliorating postoperative functioning and reducing proinflammatory muscular Toll-like receptor (TLR)–associated signaling in elderly postoperative patients. MethodsWe conducted a prospective, randomized trial comparing the effects of 3 exercise programs (CR, CA, and CR + CA) in 66 elderly patients recovering from recent hip, femur, or pelvic fracture repair surgery. The primary outcomes were changes in anatomic/physical performance parameters (ie, maximal oxygen intake, endurance, quadriceps cross-sectional area, and maximum knee-extensor force). The secondary outcomes were changes in TLR/nuclear factor kappa beta signaling pathway marker expression. ResultsThree of the 4 anatomic/physical performance parameters significantly improved for the CR and CR + CA cohorts. Muscular expression of myeloid differentiation primary response gene 88, transforming growth factor beta-activated kinase 1 (TLR signaling pathway markers), p50, p65, tumor necrosis factor α, and interleukin 6 (nuclear factor kappa beta signaling pathway markers) all showed significant reductions after CR and CR + CA. Serum expression of 2 key TLR4 ligands, heat shock protein 70 and serum amyloid A, also showed significant reductions after CR and CR + CA. ConclusionsThree months of CR or CR + CA improves maximal oxygen consumption, quadriceps cross-sectional area, and maximum knee-extensor force while lowering muscular proinflammatory signaling markers in elderly adults with postoperative deconditioning.

Functional and Structural Adaptations of Skeletal Muscle in Long-Term Juvenile Dermatomyositis: A Controlled Cross-Sectional Study.

To compare muscle strength and endurance of the knee extensors between patients with long-term juvenile dermatomyositis (DM) and controls and between patients with active disease and those with inactive disease, and to explore associations between strength/endurance and 1) clinical parameters, 2) physical activity, and 3) humoral/structural adaptation in the skeletal muscle of patients. In a cross-sectional study (44 patients and 44 age- and sex-matched controls), we tested isometric muscle strength (peak torque, in Nm) and dynamic muscle endurance (total work, in Joules) of the knee extensors, physical activity (measured by accelerometer), and serum myokine levels (by enzyme-linked immunosorbent assay). Patients were examined with validated tools (clinical muscle tests and measures of disease activity/damage and inactive disease) and using magnetic resonance imaging of the thigh muscles, which included evaluation of the quadriceps cross-sectional area (CSA). Needle biopsy samples of the vastus lateralis muscle (obtained from 12 patients ages ≥18 years) were assessed by histochemistry. After a mean ± SD disease duration of 21.8 ± 11.8 years, peak torque was lower in patients with juvenile DM compared to controls (mean difference 29 Nm, 95% confidence interval 13-46; P = 0.001). Similarly, total work of the knee extensors was lower in patients compared to controls (median 738J [interquartile range 565-1,155] versus 1,249J [interquartile range 815-1,665]; P < 0.001). Both peak torque and total work were lower in patients with active juvenile DM compared to those with inactive disease (both P < 0.019); in analyses controlled for quadriceps CSA, only total work remained lower in patients with active disease. Moreover, peak torque and total work correlated with findings from clinical muscle tests in patients with active disease (r = 0.57-0.84). Muscle biopsy results indicated that the fiber type composition was different, but capillary density was similar, between patients with active disease and those with inactive disease. In patients with long-term juvenile DM, both muscle strength and endurance of the knee extensors were lower when compared to matched controls, and also lower in patients with active disease compared to those with inactive disease. Our results indicate a need for more sensitive muscle tests in this clinical setting. We hypothesize that impaired muscle endurance in patients with active juvenile DM may be influenced by structural/functional adaptations of muscle tissue independent of muscle size.

Is Frailty Associated with Sarcopenia and Dynapenia in Lung Transplant Candidates?

Physical frailty is a predictor of pre- and early post-transplant outcomes in lung transplant patients, and may be driven by the presence of sarcopenia (loss of muscle mass), dynapenia (decline in muscle contractile function) and/or mobility limitations. The purpose of this study was to examine the association between physical frailty (Fried Frailty Index; FFI) and measures of sarcopenia, dynapenia and mobility in lung transplant candidates. As a secondary aim, we examined the relationships between sarcopenia and dynapenia. 49 lung transplant candidates from the Frailty and Sarcopenia in Organ Transplantation (FROST) cohort study were included. Frailty was evaluated using the FFI. Dynapenia was assessed by quadriceps muscle strength and power using computerized dynamometry. Sarcopenia was evaluated using B-mode ultrasound to obtain quadriceps (rectus femoris) cross-sectional area (CSA) and muscle quality (echogenicity). Mobility was measured using the Short Physical Performance Battery (SPPB). Bivariate associations were examined using Spearman's rho. The sample included 24 patients with ILD, 18 with COPD, and 7 with other diagnoses (53% females; age 59.6±13yrs, FEV1 1.14±0.66L, BMI 25.3±4.0 kg/m2). Based on the FFI, 22% were frail, 71% were pre-frail, and 6% were not frail. There was an association between FFI and the SPPB score (r= -0.41, p=0.003); specifically, with the chair stands component of the SPPB (r=0.30, p=0.035). No significant correlations were found between FFI and sarcopenia or dynapenia measures. Quadriceps muscle strength and power were associated with muscle CSA (r=0.44 and 0.47, respectively; p< 0.002) and echogenicity (r= -0.38 and -0.58, respectively; p< 0.008). Mobility limitations appear to overlap with the frailty phenotype in lung transplant candidates, however the presence of sarcopenia and dynapenia may be distinct from frailty.

Muscle Failure Promotes Greater Muscle Hypertrophy in Low-Load but Not in High-Load Resistance Training.

Lasevicius, T, Schoenfeld, BJ, Silva-Batista, C, Barros, TdS, Aihara, AY, Brendon, H, Longo, AR, Tricoli, V, Peres, BdA, and Teixeira, EL. Muscle failure promotes greater muscle hypertrophy in low-load but not in high-load resistance training. J Strength Cond Res 36(2): 346-351, 2022-The purpose of this study was to investigate the effects of an 8-week resistance training program at low and high loads performed with and without achieving muscle failure on muscle strength and hypertrophy. Twenty-five untrained men participated in the 8-week study. Each lower limb was allocated to 1 of 4 unilateral knee extension protocols: repetitions to failure with low load (LL-RF; ∼34.4 repetitions); repetitions to failure with high load (HL-RF; ∼12.4 repetitions); repetitions not to failure with low load (LL-RNF; ∼19.6 repetitions); and repetitions not to failure with high load (HL-RNF; ∼6.7 repetitions). All conditions performed 3 sets with total training volume equated between conditions. The HL-RF and HL-RNF protocols used a load corresponding to 80% 1 repetition maximum (RM), while LL-RF and LL-RNF trained at 30% 1RM. Muscle strength (1RM) and quadriceps cross-sectional area (CSA) were assessed before and after intervention. Results showed that 1RM changes were significantly higher for HL-RF (33.8%, effect size [ES]: 1.24) and HL-RNF (33.4%, ES: 1.25) in the post-test when compared with the LL-RF and LL-RNF protocols (17.7%, ES: 0.82 and 15.8%, ES: 0.89, respectively). Quadriceps CSA increased significantly for HL-RF (8.1%, ES: 0.57), HL-RNF (7.7%, ES: 0.60), and LL-RF (7.8%, ES: 0.45), whereas no significant changes were observed in the LL-RNF (2.8%, ES: 0.15). We conclude that when training with low loads, training with a high level of effort seems to have greater importance than total training volume in the accretion of muscle mass, whereas for high load training, muscle failure does not promote any additional benefits. Consistent with previous research, muscle strength gains are superior when using heavier loads.