Changes In Muscle Size Research Articles

The effect of a 12-week custom foot orthotic intervention on muscle size and muscle activity of the intrinsic foot muscle of young adults during gait termination

BackgroundThe tissue stress theory is commonly used to prescribe foot orthoses, however the mechanisms of foot orthoses are not understood well. The effect foot orthotics have on the plantar intrinsic muscles remains unclear. The study was designed to assess changes in muscle size and activity of the intrinsic muscles of individuals with pes planus after wearing custom-made foot orthotics for 12-weeks. MethodsEighteen young adults with pes planus were allocated by stratified sampling into the orthotic group (n = 9) or control group (n = 9). Ultrasonography measured the cross-sectional area of the flexor digitorum brevis, abductor digiti minimi, and abductor hallucis at baseline, 6 and 12-weeks. Subsequently, participants completed an unexpected gait termination protocol (12 of 50 trials unexpected) and average electromyography magnitude was recorded. FindingsAfter 12-weeks the orthotic group cross-sectional area significantly decreased by 9.6% (P < .001) for the flexor digitorum brevis, 17.1% for abductor digiti minimi (P < .001) and 17.4% for abductor hallucis (P < .001). There were no significant differences of muscle activity magnitude for the intrinsic muscles. InterpretationThe short-term use of custom-made foot orthoses created a decrease in muscle size of the flexor digitorium brevis, abductor digiti minimi and abductor hallucis plantar intrinsic muscles but had no effect on muscle activity. Clinically, these results help to understand the adaptations that are created when foot orthoses are supporting a pes planus foot structure when reducing plantar pressures. These findings may help enhance the prescription of foot orthoses by adding a strength program to prevent disuse atrophy of these muscles.

Strength-training effectively alleviates skeletal muscle impairments in myotonic dystrophy type 1

Myotonic dystrophy type 1 (DM1) is a multisystemic disease characterized by progressive muscle weakness. The aim of this project is to evaluate the effects of a 12-week lower limb strength training program in 11 men with DM1. Maximal isometric muscle strength, 30-second sit-to-stand, comfortable and maximal 10-m walk test (10 mwt) were evaluated at baseline, 6 and 12 weeks, and at 6 and 9 months. The one-repetition maximum strength evaluation method of the training exercises was completed at baseline, 6 and 12 weeks. Muscle biopsies were taken in the vastus lateralis at baseline and 12 weeks to evaluate muscle fiber typing and size (including atrophy/hypertrophy factors). Performance in strength and functional tests all significantly improved by week 12. Maximal isometric muscle strength of the knee extensors decreased by month 9, while improved walking speed and 30 second sit-to-stand performance were maintained. On average, there were no significant changes in fiber typing or size after training. Further analysis showed that individual abnormal hypertrophy factor at baseline could explain the different changes in muscle size among participants. Strength training induces maximal isometric muscle strength and lasting functional gains in DM1. Abnormal hypertrophy factor could be a key component to identify high and low responders to hypertrophy in DM1.

Muscle thickness and strength adaptations in dominant and non-dominant upper limbs.

It is currently unknown if muscle growth and strength gain are similar in both dominant and non-dominant limbs of the same individual with the same training load. Therefore, the objective of this study was to analyze initial muscle size and strength levels in both upper limbs and compare changes in muscle size and strength between dominant and non-dominant upper limbs with a within-individual experimental design with high-load resistance training. Ten untrained participants performed six weeks of unilateral resistance training for upper limbs (i.e., elbow flexors) using 80% of 1 repetition maximum (1RM). Muscle thickness and 1RM were assessed before and after the training period. We used a two-way repeated measures ANOVA to compared changes between limbs, effect sizes (ES) were also calculated. Muscle thickness and 1RM were not different between limbs at baseline. There was a main time effect for muscle thickness (P<0.0001; dominant: 10±4%, ES=0.83; non-dominant: 11±3%, ES=0.85) and 1RM (P<0.0001; dominant: 23±15%, ES=1.8; non-dominant: 30±17%, ES=1.9), but there was no interaction effect for muscle thickness (P=0.63) and 1RM (P=0.32). There was no difference between dominant and non-dominant limbs in volume load (ES=0.4; P=0.13). Similar baseline strength level and muscle thickness, and training volume may explain similar adaptations observed. Within-individual design seems reliable to investigate training models as both limbs adapt similarly to the same stimulus.

Does stretch training induce muscle hypertrophy in humans? A review of the literature.

Stretch training is widely used in a variety of fitness-related capacities such as increasing joint range of motion, preventing contractures and alleviating injuries. Moreover, some researches indicate that stretch training may induce muscle hypertrophy; however, studies on the topic have been primarily relegated to animal and in vitro models. The purpose of this brief review was to evaluate whether stretch training is a viable strategy to induce muscle hypertrophy in humans. An extensive literature search was performed using PubMed/MEDLINE, SciELO and Scopus databases, using terms related to stretching and muscle hypertrophy. Only human trials that evaluated changes in measures of muscle size or architecture following training protocols that it was performed stretching exercises were selected for inclusion. Of the 10 studies identified, 3 observed some significantly positive effects of stretch training on muscle structure. Intriguingly, in these studies, the stretching was carried out with an apparatus that aided in its performance, or with an external overload. In all studies, the subjects performed stretching at their own self-determined range of motion, and no effect was observed. Of the 5 available studies that integrated stretching into a resistance training programme, 2 applied the stretching in the interset rest period and were the ones that showed enhanced muscle growth. In conclusion, passive, low-intensity stretch does not appear to confer beneficial changes in muscle size and architecture; alternatively, albeit limited evidence suggests that when stretching is done with a certain degree of tensile strain (particularly when loaded, or added between active muscle contractions) may elicit muscle hypertrophy.

Eccentric, but not concentric blood flow restriction resistance training increases muscle strength in the untrained limb

ObjectivesLittle is known regarding the variables or mechanisms mediating cross-education as a result of resistance training. Therefore, the purpose of the present study was to examine the effects of low-load eccentric-only blood flow restriction (Ecc-BFR) and low-load concentric-only BFR (Con-BFR) on indices of cross-education. DesignThirty-six women were randomly assigned to 4-wks of unilateral resistance training with Ecc-BFR (n = 12), Con-BFR (n = 12) or control (no intervention, n = 12) group. Eccentric peak torque, concentric peak torque, maximal voluntary isometric contraction torque, muscle thickness, and muscle activation were assessed from the contralateral, untrained arm. ResultsMuscle strength (collapsed across mode) increased from 0-wk to 2-wks (4.9%) and 4-wks (13.0%) for Ecc-BFR only. There were increases in muscle activation (collapsed across mode and group) regardless of training modality, but there were no changes in muscle size for any of the conditions. ConclusionsThe findings of the present study indicated that low-load Ecc-BFR increased muscle strength. The increases in muscle strength as a result of Ecc-BFR were not mode-specific. Thus, low-load Ecc-BFR provides a unique alternative to maintain muscle function in an untrained limb that may have application during limb immobilization and rehabilitation practices.

Evaluating the results of resistance training using ultrasound or flexed arm circumference: a case for keeping it simple?

The present study aimed to compare changes in muscle size when measured by ultrasound (US) muscle thickness (MT) and arm circumference (AC) using data from young men.The investigation involved data from three previous studies involving a total of 67 young men who performed resistance training (RT) for 10-12 weeks. Before and after the training period, elbow flexor MT was evaluated by US and AC was measured. We conducted two-stage individual patient data random-effects meta-analyses using both Frequentist and Bayesian hypothesis testing. One-sample analyses examined the absence or presence of a change in both MT and AC, and paired analyses examined whether these differed from one another or equivalent.One-sample analysis supported that both AC (+4.9%; tp=0.0002; BF10=6,255,759,515) and MT (+3.9%; P<0.0001; BF10=7,958,241,773) suggested that change in muscle size had occurred. Frequentist paired comparisons suggested that the estimates of change between both AC and MT measures did not significantly differ (P=0.1092), but were not statistically equivalent. Bayesian paired comparisons, however, suggested that MT estimates where greater in magnitude than AC estimates for change in muscle size (BF10=16.39174).Both MT and AC are able to detect RT-induced changes in muscle size of the upper arm, but that the magnitude of changes may differ. Thus, care should be taken when comparing or combining estimates using either approach.The use of AC might be considered as a practical and low-cost alternative to detect changes in muscle size.

Use of Cine Loops and Structural Landmarks in Ultrasound Image Processing Improves Reliability and Reduces Error in the Assessment of Foot and Leg Muscles.

Foot and leg muscle strength and size are crucial to proper function. It is important to assess these characteristics reliably. Our primary objective was to compare the measurement of still images to cine loops. The secondary purpose was to determine interoperator and intraoperator reliability between operators of different experience levels using video clips and internal and external landmarks. Twelve healthy volunteers participated in our study. Internal (navicular tuberosity) and external (lateral leg length at 30% and 50% from the knee joint line) landmarks were used. Two operators each captured and later measured still and cine loop images of selected foot and leg muscles. The 12 participants included 8 male and 4 female volunteers (mean age ± SD, 23.5 ± 1.9 years). Good to excellent intraoperator and interoperator reliability was seen (intraclass correlation coefficient range of 0.946-0.998). The use of cine loops improved the intraclass correlation coefficients for both intraoperator and interoperator reliability (0.5%-4% increases). The use of cine loops decreased the intraoperator standard error of the measurement and limits of agreement of the novice operator (decreases of 45%-73% and 24%-51%, respectively), and these became comparable to those of experienced operators using still images. The interoperator standard errors of the measurement dropped by 42% to 53%, whereas the limits of agreement dropped by 27% to 40%. No substantial changes were noted in the tibialis anterior across reliability metrics. Improved protocols that take advantage of using internal bony landmarks and cine loops during both the image-gathering and measurement processes improve the reliability of research examining muscle size changes in the lower leg or foot associated with muscle changes due to exercise, injury, disuse, or disease.

Skeletal muscle mTORC1 regulates neuromuscular junction stability.

BackgroundSkeletal muscle is a plastic tissue that can adapt to different stimuli. It is well established that Mammalian Target of Rapamycin Complex 1 (mTORC1) signalling is a key modulator in mediating increases in skeletal muscle mass and function. However, the role of mTORC1 signalling in adult skeletal muscle homeostasis is still not well defined.MethodsInducible, muscle‐specific Raptor and mTOR k.o. mice were generated. Muscles at 1 and 7 months after deletion were analysed to assess muscle histology and muscle force.ResultsWe found no change in muscle size or contractile properties 1 month after deletion. Prolonging deletion of Raptor to 7 months, however, leads to a very marked phenotype characterized by weakness, muscle regeneration, mitochondrial dysfunction, and autophagy impairment. Unexpectedly, reduced mTOR signalling in muscle fibres is accompanied by the appearance of markers of fibre denervation, like the increased expression of the neural cell adhesion molecule (NCAM). Both muscle‐specific deletion of mTOR or Raptor, or the use of rapamycin, was sufficient to induce 3–8% of NCAM‐positive fibres (P < 0.01), muscle fibrillation, and neuromuscular junction (NMJ) fragmentation in 24% of examined fibres (P < 0.001). Mechanistically, reactivation of autophagy with the small peptide Tat‐beclin1 is sufficient to prevent mitochondrial dysfunction and the appearance of NCAM‐positive fibres in Raptor k.o. muscles.ConclusionsOur study shows that mTOR signalling in skeletal muscle fibres is critical for maintaining proper fibre innervation, preserving the NMJ structure in both the muscle fibre and the motor neuron. In addition, considering the beneficial effects of exercise in most pathologies affecting the NMJ, our findings suggest that part of these beneficial effects of exercise are through the well‐established activation of mTORC1 in skeletal muscle during and after exercise.

Assessing differential responders and mean changes in muscle size, strength, and the crossover effect to 2 distinct resistance training protocols.

The objective of this study was to determine differences in 2 distinct resistance training protocols and if true variability can be detected after accounting for random error. Individuals (n = 151) were randomly assigned to 1 of 3 groups: (i) a traditional exercise group performing 4 sets to failure; (ii) a group performing a 1-repetition maximum (1RM) test; and (iii) a time-matched nonexercise control group. Both exercise groups performed 18 sessions of elbow flexion exercise over 6 weeks. While both training groups increased 1RM strength similarly (∼2.4 kg), true variability was only present in the traditional exercise group (true variability = 1.80 kg). Only the 1RM group increased untrained arm 1RM strength (1.5 kg), while only the traditional group increased ultrasound measured muscle thickness (∼0.23 cm). Despite these mean increases, no true variability was present for untrained arm strength or muscle hypertrophy in either training group. In conclusion, these findings demonstrate the importance of taking into consideration the magnitude of random error when classifying differential responders, as many studies may be classifying high and low responders as those who have the greatest amount of random error present. Additionally, our mean results demonstrate that strength is largely driven by task specificity, and the crossover effect of strength may be load dependent. Novelty Many studies examining differential responders to exercise do not account for random error. True variability was present in 1RM strength gains, but the variability in muscle hypertrophy and isokinetic strength changes could not be distinguished from random error. The crossover effect of strength may differ based on the protocol employed.

Effects of concurrent exercise training on muscle dysfunction and systemic oxidative stress in older people with COPD.

Oxidative stress is associated with disease severity and limb muscle dysfunction in COPD. Our main goal was to assess the effects of exercise training on systemic oxidative stress and limb muscle dysfunction in older people with COPD. Twenty-nine outpatients with COPD (66-90years) were randomly assigned to a 12-week exercise training (ET; high-intensity interval training (HIIT) plus power training) or a control (CT; usual care) group. We evaluated mid-thigh muscle cross-sectional area (CSA; computed tomography); vastus lateralis (VL) muscle thickness, pennation angle, and fascicle length (ultrasonography); peak VO2 uptake (VO2peak ) and work rate (Wpeak ) (incremental cardiopulmonary exercise test); rate of force development (RFD); maximal muscle power (Pmax ; force-velocity testing); systemic oxidative stress (plasma protein carbonylation); and physical performance and quality of life. ET subjects experienced changes in mid-thigh muscle CSA (+4%), VL muscle thickness (+11%) and pennation angle (+19%), VO2peak (+14%), Wpeak (+37%), RFD (+32% to 65%), Pmax (+38% to 51%), sit-to-stand time (-24%), and self-reported health status (+20%) (all P<0.05). No changes were noted in the CT group (P>0.05). Protein carbonylation decreased among ET subjects (-27%; P<0.05), but not in the CT group (P>0.05). Changes in protein carbonylation were associated with changes in muscle size and pennation angle (r=-0.44 to -0.57), exercise capacity (r=-0.46), muscle strength (r=-0.45), and sit-to-stand performance (r=0.60) (all P<0.05). The combination of HIIT and power training improved systemic oxidative stress and limb muscle dysfunction in older people with COPD. Changes in oxidative stress were associated with exercise-induced structural and functional adaptations.

Ultrasound assessment of muscle mass in response to exercise training in chronic kidney disease: a comparison with MRI.

BackgroundChronic kidney disease (CKD) is a catabolic condition associated with muscle wasting and dysfunction, which associates with morbidity and mortality. There is a need for simple techniques capable of monitoring changes in muscle size with disease progression and in response to interventions aiming to increase muscle mass and function. Ultrasound is one such technique; however, it is unknown how well changes in muscle cross‐sectional area (CSA) measured using ultrasound relate to changes in whole muscle volume measured using magnetic resonance imaging. We tested whether rectus femoris CSA (RF‐CSA) could be used as a valid indication of changes in quadriceps muscle volume as a single measure of muscle size and following a 12 week exercise intervention that resulted in muscle hypertrophy.MethodsSecondary analysis of data was collected from the ExTra CKD study (ISRCTN 36489137). Quadriceps muscle size was assessed from 36 patients with non‐dialysis CKD before and after 12 weeks of supervised exercise that resulted in muscle hypertrophy.ResultsStrong positive correlations were observed between RF‐CSA and quadriceps volume at baseline (r 2 = 0.815, CI 0.661 to 0.903; P < 0.001) and following 12 week exercise (r 2 = 0.845, CI 0.700 to 0.923; P < 0.001). A moderate positive association was also observed between changes in RF‐CSA and quadriceps following exercise training (rho = 0.441, CI 0.085 to 0.697; P = 0.015). Bland–Altman analysis revealed a small bias (bias 0.6% ± 12.5) between the mean percentage changes in RF‐CSA and quadriceps volume but wide limits of agreement from −24 to 25.ConclusionsRectus femoris CSA appears to be a reliable index of total quadriceps volume as a simple measure of muscle size, both as a single observation and in response to exercise training in non‐dialysis CKD patients.

Ultrasound and MRI measured changes in muscle mass gives different estimates but similar conclusions: a Bayesian approach.

The purpose of this paper was to use a Bayesian approach to compare the relative change in muscle size between magnetic resonance imaging (MRI) and ultrasound measured muscle thickness (MTH) following 6 weeks of concentric and eccentric blood flow restricted exercise. Changes at each site were as follows: concentric 50% site (MRI: 10.2%, MTH: 8.7%), concentric 10 cm site (MRI: 12%, MTH: 4.5%), eccentric 50% site (MRI: -1.7%, MTH: 2.6%), and eccentric 10 cm site (MRI: 5.2%, MTH: 0.5%). When testing the difference between estimates using a default prior of 0.707, we provided evidence that the estimate at the 50% site of the concentric arm was similar between ultrasound and MRI [Median % (95% credible interval): -1.1 (-8.2, 5.8)]. However, evidence for other sites suggested differences or a degree of uncertainty. Both methods produce similar conclusions about the presence of growth but the magnitude of that change appears different at most sites.

Muscle Size and Strength Benefits of Functional Electrical Stimulation-Evoked Cycling Dosage in Spinal Cord Injury: A Narrative Review

Loss of sensory motor function is one of the main causes of physical and activity limitations among individual with spinal cord injury (SCI). SCI may lead to muscle paralysis, weakness and disused muscle atrophy. Evidences have shown electrical stimulation and strengthening exercise might improve lower limb muscle strength and size among individual with SCI. Functional electrical stimulation (FES) evoked cycling is one of the methods that can elicit leg muscle contractions in order to produce a cycling motion and promote the integrity of the involved muscles. Therefore, this review is to synthesize the scientific literature regarding the effects of multiple dosages of FES-evoked lower limb cycling on muscle properties. A systematic literature search from 1946 to 2016 was performed. From over 1,139 articles retrieved from the database, about 31 potentially relevant articles were retained for possible inclusion. However, only 10 articles out of 31 articles fulfilled the inclusion criteria. Although the available evidence is compelling, there is insufficient quantity and quality evidence to draw conclusions regarding the specific parameter of FES-CE that may optimally increase muscle strength, mass, and circumference. However, it can be safely concluded that an effective training session would spend for 45-60 min, 3 times a week for at least 4 weeks to see changes in muscle size and strength.

Feasibility of Dixon magnetic resonance imaging to quantify effects of physical training on muscle composition—A pilot study in young and healthy men

Changes in muscle-fat-composition affect physical performance and muscular function, like strength and power. The purpose of the present study was to investigate whether changes in soft tissue composition of the thigh and changes in muscle size and composition resulting from physical training were detectable with Dixon magnetic resonance imaging (MRI).A young and healthy subject population (n = 21, 29 ± 5 years) was split into a strength training (G_t, 11 subjects) and a control group (G_c, 10 subjects). The physical training intervention lasted over 13 weeks. Before and after this intervention a muscle performance exam and an MRI exam were conducted on all subjects. To evaluate muscle performance and the training effect, the jump height was measured using a mechanograph. Fascia, pure muscle and subcutaneous fat areas and proton density water fraction (PDWF) and proton density fat fraction (PDFF) of the left thigh were measured with a 6-point Dixon prototype MRI sequence.Muscle area changed by +7.1 ± 3.3% (p < 0.05) and +2.5 ± 5.6% (p > 0.05), and PDFF by -16.3 ± 10.4% (p < 0.05) and +5.4 ± 6.9% (p > 0.05) in G_t and G_c, respectively. Cross-sectional and longitudinal correlation coefficients R between PDFF and muscle performance were moderate (R = -0.43 and R = -0.51, respectively). The correlation was also moderate for muscle performance and a combined muscle fat per area ratio (R = -0.40 and R = -0.55, respectively).Dixon MRI is capable to measure training-related changes in muscle area and muscular fat. Both parameters correlate to muscle function. Muscle area per se does not always mirror functional parameters. Due to the complex interaction of muscle volume, muscle structure, and inter- and intramuscular coordination during muscle performance, multivariate muscle parameter models should be investigated in the future. Future studies will have to show if structural parameters mirror and explain functional muscle data both in the context of physical training and pathologies like sarcopenia.

PDK4 drives metabolic alterations and muscle atrophy in cancer cachexia

Cachexia is frequently accompanied by severe metabolic derangements, although the mechanisms responsible for this debilitating condition remain unclear. Pyruvate dehydrogenase kinase (PDK)4, a critical regulator of cellular energetic metabolism, was found elevated in experimental models of cancer, starvation, diabetes, and sepsis. Here we aimed to investigate the link between PDK4 and the changes in muscle size in cancer cachexia. High PDK4 and abnormal energetic metabolism were found in the skeletal muscle of colon-26 tumor hosts, as well as in mice fed a diet enriched in Pirinixic acid, previously shown to increase PDK4 levels. Viral-mediated PDK4 overexpression in myotube cultures was sufficient to promote myofiber shrinkage, consistent with enhanced protein catabolism and mitochondrial abnormalities. On the contrary, blockade of PDK4 was sufficient to restore myotube size in C2C12 cultures exposed to tumor media. Our data support, for the first time, a direct role for PDK4 in promoting cancer-associated muscle metabolic alterations and skeletal muscle atrophy.-Pin, F., Novinger, L. J., Huot, J. R., Harris, R. A., Couch, M. E., O'Connell, T. M., Bonetto, A. PDK4 drives metabolic alterations and muscle atrophy in cancer cachexia.

Is muscle growth a mechanism for increasing strength?

Skeletal muscle hypertrophy commonly occurs with repeated bouts of resistance exercise as well as following the administration of exogenous drugs. This increase in muscle size is thought to be mechanistically important for the increase in muscle function. However, at present, there is no experimental evidence that would support any paradigm in which muscle hypertrophy is a mechanism for increasing strength with exercise. Therefore, it seems reasonable to also question the importance of changes in muscle size for changes in muscle strength (function) following exogenous drugs as well as aging, where both muscle size and strength decrease. The purpose of this paper is to discuss whether changes in muscle size contribute to changes in voluntary strength following exercise, pharmaceutical interventions, and aging. We also aim to provide potential mechanisms (central and peripheral) for the change in strength as well as outline study designs to better address this question. Herein, we suggest that there are dissociations between changes in muscle size and strength following exercise, anabolic drug administration, and aging (to a point). These dissociations occur throughout the literature, suggesting that these changes may be completely separate phenomena. We are not dismissing the potential importance of maintaining muscle mass, particularly in clinical populations. What we are suggesting, however, is that muscle function may not necessarily be improved by these exercise or pharmacological induced increases in muscle size. Exploring mechanisms and explanations beyond just changes in muscle size may improve therapy targeted at improving muscle function.

Non‐failure blood flow restricted exercise induces similar muscle adaptations and less discomfort than failure protocols

Low-load blood flow restricted resistance exercise (BFRE) performed to volitional failure is suggested to constitute an effective method for producing increases in muscle size and function. However, BFRE to failure may entail high levels of perceived exertion, discomfort, and/or delayed onset of muscle soreness (DOMS). The aim of the study was to compare BFRE performed to volitional failure (F-BFRE) vs non-failure BFRE (NF-BFRE) on changes in muscle size, function and perceptual responses. Fourteen young untrained males had one leg randomized to knee extension F-BFRE while the contralateral leg performed NF-BFRE. The training consisted of 22 exercise bouts over an 8-week period. Whole-muscle cross-sectional area (CSA) of quadriceps components, muscle function, and DOMS were assessed before and after the training period. Perceived exertion and discomfort were registered during each exercise bout. Both F-BFRE and NF-BFRE produced regional increases in muscle CSA in the range of: quadriceps (2.5%-3.8%), vastus lateralis (8.1%-8.5%), and rectus femoris (7.9%-25.0%). All without differences between leg. Muscle strength (6.8%-11.5%) and strength-endurance capacity (13.9%-18.6%) also increased to a similar degree in both legs. Less perceived exertion, discomfort, and DOMS were reported with NF-BFRE compared to F-BFRE. In conclusion, non-failure BFRE enables increases in muscle size and muscle function, while involving reduced perceptions of exertion, discomfort, and DOMS. Non-failure BFRE may be a more feasible approach in clinical settings.

Age related changes in muscle size and strength across the lifespan in individuals with cerebral palsy

Age related changes in muscle size and strength across the lifespan in individuals with cerebral palsy

Gluteal muscle size and fatty infiltration in women with greater trochanteric pain syndrome

Introduction: Greater trochanteric pain syndrome (GTPS) is a debilitating, chronic condition, most prevalent in women. Physical function, such as walking, is impaired in people with GTPS, severely impacting quality of life. In addition, a key muscle group with demonstrable reduction in strength are the hip abductors. An understanding of the specific muscles affected will help guide targeted rehabilitation options. Current evidence for gluteal muscle size changes in people with GTPS is scarce, with methodological limitations, and fatty infiltration has not yet been described in this population. This study aimed to compare gluteal muscle size and fatty infiltration using magnetic resonance imaging (MRI) in women with symptomatic GTPS compared to asymptomatic controls.

A Comparison of Foot Strengthening versus Minimal Footwear Use on Intrinsic Muscle Size and Strength

Category: Other Introduction/Purpose: The intrinsic muscles of the arch have been classified as the core of the foot. Intrinsic foot muscles (IFM) work as local stabilizers and extrinsic foot muscles (EFM) work as global movers to help control the pronation of the foot. These muscles prevent excessive strain of the MLA. Previous research has shown that strengthening IFM may reduce pain and improve function in people with plantar fasciitis. Additionally, habitual use of minimal shoes that lack support of the arch require greater demand on the intrinsic muscles. The purpose of this study was to determine the effectiveness of two different strengthening interventions on IFM and EFM size and strength. Methods: 57 healthy runners (avg 15-30 mpw) were randomly assigned to a foot strengthening (FS, n=19), a minimal shoe walking (MSW, n=19), or a control group (C, n=19). Baseline cross-sectional areas of abductor hallucis, quadratus plantae, flexor digitorum brevis, and flexor digitorum longus, and thickness of the flexor hallucis brevis, tibialis posterior, and tibialis anterior were obtained with ultrasound using a 10 MHz linear probe. Doming, great toe flexion and lateral toes flexion strength were also measured using a custom-built dynamometer. The FS group then underwent an 8 wk foot and ankle strengthening program. The MSW group progressively walked in minimal footwear from 2,500-7,000 over the course of 8 wks. All groups, including C, maintained normal running mileage in conventional footwear throughout the 8 wks. Size and strength measures were then repeated. A repeated measures ANCOVA with a post-hoc test was used to determine differences in size and strength between groups. Results: All muscles measured in the FS and MSW groups increased significantly in size from weeks 0-8. There were no changes in muscle size in the C group. The FS group experienced significantly greater size changes for the flexor hallucis brevis than the MSW group. All other changes in muscle size were not significant between the FS and MSW groups. The FS and MSW groups showed significant increases in strength in all 3 tests from week 0-8. Strength of the control group did not change at any time. The increases in strength in the FS and MSW groups were not significantly different than each other. Conclusion: Exercises that target the intrinsic and extrinsic foot muscles are effective in increased strength and size of the muscles. However, similar increases in strength and size can be obtained by progressive walking in minimal footwear. Combining both these approaches may have an even greater effect. Stronger feet may offer greater protection against overuse injuries such as plantar fasciitis.