Changes In Muscle Cross-sectional Area Research Articles

Sex Differences in Muscle Hypertrophy Response to Training of the Peroneus Longus and Peroneus Brevis Muscles

Category: Ankle; Trauma Introduction/Purpose: It has been reported that there are no significant sex differences in muscle hypertrophy response after strength training for the quadriceps muscles (Roth et al., 2002). After an ankle sprain, the peroneus longus (PL) and peroneus brevis (PB) muscles develop morphological changes and dysfunction, which requires training for the PL and PB (Arima et al., 2022). However, to our knowledge, sex differences in muscle hypertrophic response to the PL and PB training have not been studied. This study aimed to compare the changes in muscle cross-sectional area (CSA) after the PL and PB training between men and women, and to examine the possible influence of sex on the muscle hypertrophy response to training for the PL and PB. Methods: Eighteen healthy adults (9 men and 9 women) were participated. All participants performed two types of ankle eversion training on the right leg with Thera-Band on separate days. PL training in which the Thera-Band was placed on the ball of foot and pushed out from the contact point, and PB training in which the Thera-Band was pushed out from the base of the fifth metatarsal. An ultrasound imaging device was used to measure the CSA of the peroneal muscles at the proximal 25% and distal 75% of the line connecting the fibular head and the lateral malleolus. The measurements were taken before (pre), immediately after (post), 10, 20, and 30 minutes after each training, and the amount of change over time relative to pre was calculated. Unpaired t-tests were used to compare the change in CSA between men and women at each time. Statistical significance was set at 5%. Results: After the PL training, the amount of change in CSA of the PL was significantly greater by 29.7 mm² in women than in men only at post (p < 0.05), but there were no significant differences at other times (10 minutes: p = 0.06, 20 minutes: p = 0.19, 30 minutes: p = 0.11). After the PB training, the amount of change in CSA of the PB was significantly greater by 16.0 mm² at post (p < 0.05) and 3.1 mm² at 30 minutes (p < 0.01) in women than in men. However, there were no significant differences at 10 and 20 minutes (10 minutes: p = 0.27, 20 minutes: p = 0.55). Conclusion: The results indicate that sex differences may influence the immediate muscle hypertrophic response to training for the PL and PB. The immediate muscle hypertrophy response after training is due to edema resulting from muscle damage, reflecting an immediate effect of training (Damas et al., 2016), which suggests that women are more likely to achieve effects of the PL and PB training than men in similar loads. Furthermore, the results also show that the effect of the PB training may be maintained longer in women, thus it is necessary to investigate the long-term effects of the training in the future.

Functional improvements to 6months of physical activity are not related to changes in size or density of multiple lower-extremity muscles in mobility-limited older individuals.

Older adults are encouraged to engage in multicomponent physical activity, which includes aerobic and muscle-strengthening activities. The current work is an extension of the Vitality, Independence, and Vigor in the Elderly 2 (VIVE2) study - a 6-month multicenter, randomized, placebo-controlled trial of physical activity and nutritional supplementation in community dwelling 70-year-old seniors. Here, we examined whether the magnitude of changes in muscle size and quality differed between major lower-extremity muscle groups and related these changes to functional outcomes. We also examined whether daily vitamin-D-enriched protein supplementation could augment the response to structured physical activity. Forty-nine men and women (77±5yrs) performed brisk walking, muscle-strengthening exercises for the lower limbs, and balance training 3 times weekly for 6months. Participants were randomized to daily intake of a nutritional supplement (20g whey protein+800IU vitamin D), or a placebo. Muscle cross-sectional area (CSA) and radiological attenuation (RA) were assessed in 8 different muscle groups using single-slice CT scans of the hip, thigh, and calf at baseline and after the intervention. Walking speed and performance in the Short Physical Performance Battery (SPPB) were also measured. For both CSA and RA, there were muscle group × time interactions (P<0.01). Significant increases in CSA were observed in 2 of the 8 muscles studied, namely the knee extensors (1.9%) and the hip adductors (2.8%). For RA, increases were observed in 4 of 8 muscle groups, namely the hip flexors (1.1HU), hip adductors (0.9HU), knee extensors (1.2HU), and ankle dorsiflexors (0.8HU). No additive effect of nutritional supplementation was observed. While walking speed (13%) and SPPB performance (38%) improved markedly, multivariate analysis showed that these changes were not associated with the changes in muscle CSA and RA after the intervention. We conclude that this type of multicomponent physical activity program results in significant improvements in physical function despite relatively small changes in muscle size and quality of some, but not all, of the measured lower extremity muscles involved in locomotion.

Low-Load Blood Flow Restriction and High-Load Resistance Training Induce Comparable Changes in Patellar Tendon Properties.

Low-load resistance training with blood flow restriction (LL-BFR) has emerged as a viable alternative to conventional high-load (HL) resistance training regimens. Despite increasing evidence confirming comparable muscle adaptations between LL-BFR and HL resistance exercise, only very little is known about tendinous mechanical and morphological adaptations after LL-BFR. Therefore, the aim of the present study was to examine the effects of 14 wk of LL-BFR and HL training on patellar tendon adaptations. Twenty-nine recreationally active male participants were randomly allocated into the following two groups: LL-BFR resistance training (20%-35% one-repetition maximum (1RM)) or HL resistance training (70%-85% 1RM). Both groups trained three times per week for 14 wk. One week before and after the intervention, patellar tendon mechanical and morphological properties were assessed via ultrasound and magnetic resonance imaging. In addition, changes in muscle cross-sectional area were quantified by magnetic resonance imaging and muscle strength via dynamic 1RM measurements. The findings demonstrated that both LL-BFR and HL training resulted in comparable changes in patellar tendon stiffness (LL-BFR: +25.2%, P = 0.003; HL: +22.5%, P = 0.024) without significant differences between groups. Similar increases in tendon cross-sectional area were observed in HL and LL-BFR. Muscle mass and strength also significantly increased in both groups but were not statistically different between HL (+38%) and LL-BFR (+34%), except for knee extension 1RM where higher changes were seen in LL-BFR. The present results support the notion that both HL and LL-BFR cause substantial changes in patellar tendon properties, and the magnitude of changes is not significantly different between conditions. Further studies that examine the physiological mechanisms underlying the altered tendon properties after LL-BFR training are needed.

Volume of Gluteus Maximus and Minimus Increases After Hip Arthroscopy for Femoroacetabular Impingement Syndrome

To investigate the change in muscle volume around the hip in patients with femoroacetabular impingement (FAI) after arthroscopy and evaluate other factors related to muscle change. We performed a retrospective review of magnetic resonance imaging data of patients with FAI who underwent hip arthroscopy. Magnetic resonance imaging was obtained pre- and postoperatively. The cross-sectional area (CSA) of muscles were determined on axial images. The Wilcoxon signed-rank test was used to determine the differences between pre- and postoperative hip muscle CSA. The correlations of change in muscle CSA with age, sex, body mass index, pain level, preoperative symptom duration, follow-up time, and multiple validated patient-reported outcomes were also analyzed with a Spearman rank correlation test. Fifty-one patients with a mean age of 36.5 ± 5.6 years were included and analyzed. The follow-up was 26.6 ± 0.5 months (range, 24-40 months), and 27 (52.9%) were women. Patients with FAI showed increased hip muscle CSA of gluteus maximus (P= .002) and gluteus minimus (P= .001). Post- compared with preoperative, the value for the change in medius CSA was underpowered, and no differences in other hip muscle CSAs were observed. The increased muscle CSA of the gluteus maximus was significantly correlated with the improvement of modified Harris Hip Score (ρ= 0.404; P= .003). The increased muscle CSA of the gluteus minimus was significantly correlated with the improvement of pain Visual Analog Scale (ρ= 0.452; P= .001). Age, body mass index, sex, symptom duration, and follow-up time were not significantly correlated with change in muscle CSA. Patients with FAI have a significantly increased postoperative muscle CSA of the gluteus maximus (7.8%) and the gluteus minimus (11.6%) compared with preoperative values. The increased muscle CSA of the gluteus maximus and gluteus minimus was significantly correlated with improvement in modified Harris Hip Score and pain Visual Analog Scale, respectively. The increase of muscle volume may be associated with the improvement of subjective function and pain relief. Level IV, therapeutic case series.

Greater maintenance of bone mineral content in male than female athletes and in sprinting and jumping than endurance athletes: a longitudinal study of bone strength in elite masters athletes

SummaryWe investigated longitudinal changes in tibia bone strength in master power (jumping and sprinting) and endurance (distance) athletes of both sexes. Bone mass but not cross-sectional moment of inertia was better maintained in power than endurance athletes over time, particularly in men and independent of changes in performance.ObjectiveAssessment of effects of sex and athletic discipline (lower limb power events, e.g. sprint running and jumping versus endurance running events) on longitudinal changes in bone strength in masters athletes.MethodsWe examined tibia and fibula bone properties at distal (4% distal-proximal tibia length) and proximal (66% length) sites using peripheral quantitative computed tomography (pQCT) in seventy-one track and field masters athletes (30 male, 41 female, age at baseline 57.0 ± 12.2 years) in a longitudinal cohort study that included at least two testing sessions over a mean period of 4.2 ± 3.1 years. Effects of time, as well as time × sex and time × discipline interactions on bone parameters and calf muscle cross-sectional area (CSA), were examined.ResultsEffects of time were sex and discipline-dependent, even following adjustment for enrolment age, sex and changes in muscle CSA and athletic performance. Male sex and participation in power events was associated with better maintenance of tibia bone mineral content (BMC, an indicator of bone compressive strength) at 4% and 66% sites. In contrast, there was no strong evidence of sex or discipline effects on cross-sectional moment of inertia (CSMI, an indicator of bone bending and torsional strength—P > 0.3 for interactions). Similar sex and discipline-specific changes were also observed in the fibula.ConclusionsResults suggest that male athletes and those participating in lower limb power-based rather than endurance-based disciplines have better maintenance of bone compressive but not bending and torsional strength.

Myofibrillar protein synthesis and muscle hypertrophy individualized responses to systematically changing resistance training variables in trained young men.

The manipulation of resistance training (RT) variables is used among athletes, recreational exercisers, and compromised populations (e.g., elderly) attempting to potentiate muscle hypertrophy. However, it is unknown whether an individual's inherent predisposition dictates the RT-induced muscle hypertrophic response. Resistance-trained young [26 (3) y] men (n = 20) performed 8 wk unilateral RT (2 times/wk), with 1 leg randomly assigned to a standard progressive RT [control (CON)] and the contralateral leg to a variable RT (VAR; modulating exercise load, volume, contraction type, and interset rest interval). The VAR leg completed all 4 RT variations every 2 wk. Bilateral vastus lateralis cross-sectional area (CSA) was measured, pre- and post-RT and acute integrated myofibrillar protein synthesis (MyoPS) rates were assessed at rest and over 48 h following the final RT session. Muscle CSA increase was similar between CON and VAR (P > 0.05), despite higher total training volume (TTV) in VAR (P < 0.05). The 0-48-h integrated MyoPS increase postexercise was slightly greater for VAR than CON (P < 0.05). All participants were considered "responders" to RT, although none benefited to a greater extent from a specific protocol. Between-subjects variability (MyoPS, 3.30%; CSA, 37.8%) was 40-fold greater than the intrasubject (between legs) variability (MyoPS, 0.08%; CSA, 0.9%). The higher TTV and greater MyoPS response in VAR did not translate to a greater muscle hypertrophic response. Manipulating common RT variables elicited similar muscle hypertrophy than a standard progressive RT program in trained young men. Intrinsic individual factors are key determinants of the MyoPS and change in muscle CSA compared with extrinsic manipulation of common RT variables.NEW & NOTEWORTHY Systematically manipulating resistance training (RT) variables during RT augments the stimulation of myofibrillar protein synthesis (MyoPS) and training volume but fails to potentiate muscle hypertrophy compared with a standard progressive RT. Any modest further MyoPS increase and higher training volumes do not reflect in a greater hypertrophic response. Between-subject variability was 40-fold greater than the variability promoted by extrinsic manipulation of RT variables, indicating that individual intrinsic factors are stronger determinants of the hypertrophic response.

Individual Muscle Hypertrophy and Strength Responses to Traditional Resistance Training vs Drop Set System

category: Fitness Assessment, Exercise Training, and Performance of Athletes and Healthy People - 102 Exercise Training Interventions in Healthy People Cleiton Augusto Libardi, Vitor Angleri, Carlos Ugrinowitsch. Federal University of São Carlos, SP, Brazil; University of São Paulo, SP, Brazil. To maximize, or to prevent the stagnation of gains in muscle strength and mass, coaches have used resistance training (RT) systems. It has been showed that traditional RT (TRAD) and drop-set systems (DS) result in similar gains in muscle hypertrophy and strength. However, a large variability has been reported for muscle strength and hypertrophy outcomes even when subjects perform RT programs. PURPOSE: The aim of this study was to compare the individual muscle mass and strength gains to TRAD vs DS in well trained young men. METHODS: We used a within-subjects design in which 14 participants had one leg randomly assigned to TRAD (3-5 sets of 6-12 repetitions at 75% 1RM) and the other to DS [3-5 sets of ~50-75% 1RM to muscle failure]). Participants had one leg fixed in the TRAD while the contralateral leg performed either DS to allow for total training volume (TTV) equalization. Muscle cross-sectional area (CSA) and one repetition maximum (1RM) were assessed at baseline and after 12-wks of RT. For group analyses, the accumulated TTV and changes in muscle CSA and 1-RM values were compared between TRAD and DS using paired t-tests. For individual analyses, if an individual that showed a difference in the response (for CSA or 1RM increases) from TRAD or DS (or vice-versa) within 2 typical errors (CSA typical error [TE] = 2.20%, 1RM TE = 2.62%), no difference in the response between RT schemes was considered. RESULTS: No significant differences in TTV (P > 0.05) were detected between protocols TRAD and DS. Muscle CSA and 1RM values increased significantly and similarly for TRAD and DS (P < 0.0001). This study highlights that some individuals showed greater muscle strength gains following TRAD (35.7% of individuals), and other show similar responses between TRAD and DS (64.3% of individuals). For muscle CSA, individuals showed similar responses to TRAD and DS. CONCLUSION: Despite the analysis groups show similar gains in strength and muscle hypertrophy, some individuals show greater strength gains for TRAD compared to the DS.

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.

PQCT- and Ultrasound-based Muscle and Fat Estimate Errors after Resistance Exercise.

Resistance exercise increases blood flow, induces osmotic and hydrostatic fluid shifts during and immediately after exercise, and may trigger inflammatory responses for several days in the working muscle. The resultant muscle swelling can subsequently affect muscle size and quality assessments. However, the effects of muscle swelling on x-ray attenuation of adipose estimate errors are unknown. Peripheral quantitative computed tomography (pQCT) and ultrasonography were used to assess muscle and adipose tissue properties of both upper arms before, 24, 48, and 72 h after unilateral resistance exercise. Recreationally active participants (n = 17) completed the exercise while their contralateral limb served as a control. Resistance exercise resulted in a significant increase in pQCT-derived muscle cross-sectional area (includes intermuscular adipose tissue [IMAT] area), muscle area (excludes IMAT area) and IMAT area, and ultrasound-derived muscle thickness at 24, 48, and 72 h. A significant decrease in pQCT-derived muscle density was also detected as well as an increase in ultrasound-derived echo intensity at 48 and 72 h. The changes in muscle area, IMAT area, and muscle density were significantly correlated with changes in echo intensity, whereas the changes in muscle cross-sectional area and IMAT area were significantly correlated with changes in muscle thickness. Unaccustomed resistance exercise can cause errors in pQCT- and ultrasound-based muscle and adipose estimates for at least 72 h. These errors are the result of muscle swelling likely caused by muscle blood flow and inflammation-dependent fluid shifts in muscle. These findings may have implications for measurements in other inflammatory conditions.

Cross-sectional area of the paraspinal muscles and its association with muscle strength among fighter pilots: a 5-year follow-up

BackgroundA small cross sectional area (CSA) of the paraspinal muscles may be related to low back pain among military aviators but previous studies have mainly concentrated on spinal disc degeneration. Therefore, the primary aim of the study was to investigate the changes in muscle CSA and composition of the psoas and paraspinal muscles during a 5-year follow up among Finnish Air Force (FINAF) fighter pilots.MethodsStudy population consisted of 26 volunteered FINAF male fighter pilots (age: 20.6 (±0.6) at the baseline). The magnetic resonance imaging (MRI) examinations were collected at baseline and after 5 years of follow-up. CSA and composition of the paraspinal and psoas muscles were obtained at the levels of 3–4 and 4–5 lumbar spine. Maximal isometric strength tests were only performed on one occasion at baseline.ResultsThe follow-up comparisons indicated that the mean CSA of the paraspinal muscles increased (p < 0.01) by 8% at L3–4 level and 7% at L4–5 level during the 5-year period. There was no change in muscle composition during the follow-up period. The paraspinal and psoas muscles’ CSA was positively related to overall maximal isometric strength at the baseline. However, there was no association between LBP and muscle composition or CSA.ConclusionsThe paraspinal muscles’ CSA increased among FINAF fighter pilots during the first 5 years of service. This might be explained by physically demanding work and regular physical activity. However, no associations between muscle composition or CSA and low back pain (LBP) experienced were observed after the five-year follow-up.

Dietary protein intake is not associated with 5-y change in mid-thigh muscle cross-sectional area by computed tomography in older adults: the Health, Aging, and Body Composition (Health ABC) Study

ABSTRACTBackgroundA higher protein intake is suggested to preserve muscle mass during aging and may therefore reduce the risk of sarcopenia.ObjectivesWe explored whether the amount and type (animal or vegetable) of protein intake were associated with 5-y change in mid-thigh muscle cross-sectional area (CSA) in older adults (n = 1561).MethodsProtein intake was assessed at year 2 by a Block food-frequency questionnaire in participants (aged 70–79 y) of the Health, Aging, and Body Composition (Health ABC) Study, a prospective cohort study. At year 1 and year 6 mid-thigh muscle CSA in square centimeters was measured by computed tomography. Multiple linear regression analysis was used to examine the association between energy-adjusted protein residuals in grams per day (total, animal, and vegetable protein) and muscle CSA at year 6, adjusted for muscle CSA at year 1 and potential confounders including prevalent health conditions, physical activity, and 5-y change in fat mass.ResultsMean (95% CI) protein intake was 0.90 (0.88, 0.92) g · kg–1 · d–1 and mean (95% CI) 5-y change in muscle CSA was −9.8 (−10.6, −8.9) cm2. No association was observed between energy-adjusted total (β = −0.00; 95% CI: −0.06, 0.06 cm2; P = 0.982), animal (β = −0.00; 95% CI: −0.06, 0.05 cm2; P = 0.923), or plant (β = +0.07; 95% CI: −0.06, 0.21 cm2; P = 0.276) protein intake and muscle CSA at year 6, adjusted for baseline mid-thigh muscle CSA and potential confounders.ConclusionsThis study suggests that a higher total, animal, or vegetable protein intake is not associated with 5-y change in mid-thigh muscle CSA in older adults. This conclusion contradicts some, but not all, previous research. This trial was registered at www.trialregister.nl as NTR6930.

The validity of the EMG and MMG techniques to examine muscle hypertrophy

Objective: The purpose of this investigation was to examine the ability of the electromyographic (EMG) and mechanomyographic (MMG) amplitude versus torque relationships to track group and individual changes in muscle hypertrophy as a result of resistance training. Approach: Twelve women performed four weeks of forearm flexion blood flow restriction (BFR) resistance training at a frequency of three times per week. The training was performed at an isokinetic velocity of 120° · s−1 with a training load that corresponded to 30% of concentric peak torque. Muscle hypertrophy was determined using ultrasound-based assessments of muscle cross-sectional area from the biceps brachii. Training-induced changes in the slope coefficients of the EMG amplitude and MMG amplitude versus torque relationships were determined from the biceps brachii during incremental (10%–100% of maximum) isometric muscle actions. Main results: There was a significant (p < 0.001; d = 2.15) mean training-induced increase in muscle cross-sectional area from 0 week (mean ± SD = 5.86 ± 0.65 cm2) to 4 weeks (7.42 ± 0.80 cm2), a significant (p = 0.023; d = 0.36) decrease in the EMG amplitude versus torque relationship (50.70 ± 20.41 to 43.82 ± 17.76 µV · Nm−1), but no significant (p = 0.192; d = 0.17) change in the MMG amplitude versus torque relationship (0.018 ± 0.009 to 0.020 ± 0.009 m · s−2 · Nm−1). There was, however, great variability for the individual responses for the EMG and MMG amplitude versus torque relationships. Significance: The results of the present study indicated that the EMG amplitude, but not the MMG amplitude versus torque relationship was sensitive to mean changes in muscle cross-sectional area during the early-phase of resistance training. There was, however, great variability for the individual EMG amplitude versus torque relationships that limits its application for identifying individual changes in muscle hypertrophy as a result of BFR.

Effects of Prolonging Eccentric Phase Duration in Parallel Back-Squat Training to Momentary Failure on Muscle Cross-Sectional Area, Squat One Repetition Maximum, and Performance Tests in University Soccer Players.

Shibata, K, Takizawa, K, Nosaka, K, and Mizuno, M. Effects of prolonging eccentric phase duration in parallel back-squat training to momentary failure on muscle cross sectional area, squat one repetition maximum, and performance tests in university soccer players. J Strength Cond Res 35(3): 668-674, 2021-This study aimed to compare 2 squat training programs repeated until momentary failure with different eccentric phase duration (2 seconds vs. 4 seconds) on the changes in muscle cross-sectional area, squat 1 repetition maximum (1RM), squat jump (SJ), and countermovement jump (CMJ) height, agility (T-test), and Yo-Yo intermittent recovery test (YY-IR2). Male university soccer players (19.9 ± 0.9 years, 172.2 ± 3.8 cm, 66.1 ± 6.6 kg) were randomly assigned to one of the 2 groups; CON for 2 seconds and ECC for 4 seconds (C2/E4, n = 11) or CON for 2 seconds and ECC for 2 seconds (C2/E2, n = 11). They performed parallel back-squat exercises twice a week for 6 weeks using 75% 1RM weight to momentary failure in each set for 3 sets with each protocol. Outcome measurements were taken before (Pre) and after 3 (Mid; 1RM, SJ, and CMJ only), and at 6 weeks (Post). One repetition maximum increased more (p < 0.05) for C2/E2 (Pre: 95.9 ± 12.2 kg, Mid: 108.2 ± 15.4 kg, Post: 113.6 ± 14.8 kg) than C2/E4 (95.5 ± 12.9 kg, 102.7 ± 15.6 kg, 105.5 ± 14.9 kg, respectively). Cross-sectional area (50% of the thigh length: 3.5 ± 2.8%), SJ (6.7 ± 8.9%) and CMJ height (6.3 ± 8.6%) increased similarly between C2/E2 and C2/E4, but no significant changes in T-test or YY-IR2 were evident in either group. These results suggest that increasing the ECC phase duration during squat exercises does not produce greater training effects when compared with a shorter ECC phase-duration program with momentary failure.

Markers of oxidative stress, skeletal muscle mass and function, and their responses to resistance exercise training in older adults

BackgroundOxidative stress (OS) negatively affects skeletal muscle homeostasis in experimental models of ageing. However, little is known about the associations between circulating OS markers and parameters of muscle mass and function, and their responses to exercise training, in humans. MethodsMaximal voluntary contraction (MVC, primary outcome) and isokinetic torque of the knee extensors at 30° s−1 (MIT), muscle cross-sectional area (MCSA) and quality (MQ, secondary outcomes), and plasma concentrations of malondialdehyde (MDA, pro-OS), homocysteine (HCY, pro-OS), taurine (TAU, anti-OS), and protein sulphydryl groups (PSH, anti-OS) were measured in 27 healthy older males and 23 females at baseline and after an 18-week resistance exercise program, with or without a nutritional intervention (fish oil vs. placebo). ResultsAfter adjusting for age, glomerular filtration rate, and nutritional intervention, there were no significant correlations between baseline OS markers and muscle parameters, barring a positive association between TAU and MIT in females (r = 0.53, P = .035) and between MDA and MCSA in males (r = 0.69, P = .001). Training did not significantly change OS markers, except for a reduction in MDA in females (−0.27 μmol/L, 95% CI −0.51 to −0.02, P = .034). In females, there were significant correlations between baseline MDA and exercise-induced changes in MVC (P = .018), baseline TAU and changes in MCSA (P = .026), and baseline HCY and changes in MCSA (P = .046) and MQ (P = .022). In males, baseline MDA was significantly associated with exercise-induced changes in MVC (P = .040). ConclusionsPlasma MDA, HCY, and TAU were significantly associated with baseline and/or exercise-induced changes in muscle mass and function in healthy older adults, primarily in females. Pending further confirmation in other populations, specific OS markers, particularly MDA, might predict muscle responses to resistance exercise programs in old age.

Infraspinatus Cross-Sectional Area and Shoulder Range of Motion Change Following Live-Game Baseball Pitching.

Following a baseball pitching bout, changes can occur to glenohumeral range of motion that could be linked to injury. These effects are in part due to the posterior shoulder's eccentric muscle activity, which can disrupt muscle contractile elements and lead to changes in muscle cross-sectional area (CSA), as measured by ultrasound. To assess changes in muscle CSA, and range of motion immediately before and after pitching, and days 1 to 5 following pitching. Repeated measures. Satellite athletic training room. Ten elite college baseball pitchers participating in the fall season (age: 18.8 [1.2]y, height: 189.2 [7.3]cm, mass: 93.1 [15.3]kg, 8 starters, 2 long relievers). A pitching bout of at least 25 pitches (63.82 [17.42] pitches). Dominant and nondominant infraspinatus CSA, as measured by ultrasound, and glenohumeral range of motion including internal rotation (IRROM), external rotation (ERROM), and total rotation range of motion (TROM) before pitching, after pitching, and days 1 to 5 following the pitching bout. Dominant limb CSA significantly increased day 1 after pitching, and returned to baseline on day 2 (P < .001). Dominant and nondominant TROM did not change until day 5 (4.4°, P < .001) and day 3 (4.5°, P < .001), respectively, where they increased. Dominant IRROM was significantly decreased for 3 days (day 1: 1.9°, P < .001; day 2: 3.1°, P < .001; day 3: 0.3°, P < .001) following pitching and returned to baseline on day 4, with no such changes in the nondominant limb. Dominant external rotation significantly increased immediately post pitching (4.4°, P < .001) but returned to baseline by day 1. The results of the study demonstrate that infraspinatus CSA does not recover until 2 days following pitching, and IRROM does not recover until 4 days following pitching. Baseball pitching elicits damage to the posterior shoulder muscle architecture, resulting in changes to physical characteristics that last up to 4 days following pitching.

Sex Differences in the Associations between L-Arginine Pathway Metabolites, Skeletal Muscle Mass and Function, and their Responses to Resistance Exercise, in Old Age.

The current study was designed to explore the associations between L-arginine metabolites and muscle mass and function in old age, which are largely unknown. The study used a randomised, double-blind, placebo-controlled design. The study was carried out in a laboratory setting. 50 healthy older adults [median age 70 years (IQR 67-73); 27 males]. Participants undertook an 18-week resistance exercise program, and a nutritional intervention (fish oil vs. placebo). Serum homoarginine, ornithine, citrulline, asymmetric dimethylarginine (ADMA), NG-monomethyl-L-arginine (L-NMMA), and symmetric dimethylarginine (SDMA), maximal voluntary contraction (MVC) and isokinetic torque of the knee extensors at 30° s-1 (MIT), muscle cross sectional area (MCSA) and quality (MQ) were measured at baseline and after the intervention. No significant exercise-induced changes were observed in metabolite concentrations. There were significant sex differences in the associations between metabolites and muscle parameters. After adjusting for age, glomerular filtration rate and fish oil intervention, citrulline (P=0.002) and ornithine (P=0.022) were negatively associated with MCSA at baseline in males but not females. However, baseline citrulline was negatively correlated with exercise-induced changes in MVC (P=0.043) and MQ (P=0.026) amongst females. Furthermore, amongst males, baseline homoarginine was positively associated with exercise-induced changes in MVC (P=0.026), ADMA was negatively associated with changes in MIT (P=0.026), L-NMMA (p=0.048) and ornithine (P<0.001) were both positively associated with changes in MCSA, and ornithine was negatively associated with changes in MQ (P=0.039). Therefore, barring citrulline, there are significant sex differences in the associations between L-arginine metabolites and muscle mass and function in healthy older adults. These metabolites might enhance sarcopenia risk stratification, and the success of exercise programs, in old age.

Change in muscle cross-sectional area and its influence on functional outcome in ventilated intensive care unit patients：A prospective study.

Change in muscle cross-sectional area and its influence on functional outcome in ventilated intensive care unit patients：A prospective study.

Panoramic ultrasound: a novel and valid tool for monitoring change in muscle mass.

BackgroundThe strong link between reduced muscle mass and morbidity and mortality highlights the urgent need for simple techniques that can monitor change in skeletal muscle cross‐sectional area (CSA). Our objective was to examine the validity of panoramic ultrasound to detect change in quadriceps and gastrocnemius size in comparison with magnetic resonance imaging (MRI) in subjects randomized to 70 days of bed rest (BR) with or without exercise.MethodsPanoramic ultrasound and MRI images of the quadriceps and gastrocnemius muscles were acquired on the right leg of 27 subjects (26 male, 1 female; age: 34.6 ± 7.8 years; body mass: 77.5 ± 10.0 kg; body mass index: 24.2 ± 2.8 kg/m2; height: 179.1 ± 6.9 cm) before (BR‐6), during (BR3, 7, 11, 15, 22, 29, 36, 53, 69), and after (BR+3, +6, +10) BR. Validity of panoramic ultrasound to detect change in muscle CSA was assessed by Bland–Altman plots, Lin's concordance correlation coefficient (CCC), sensitivity, specificity, positive predictive value, and negative predictive value.ResultsSix hundred ninety‐eight panoramic ultrasound CSA and 698 MRI CSA measurements were assessed. Concordance between ultrasound and MRI was excellent in the quadriceps (CCC: 0.78; P < 0.0001), whereas there was poor concordance in the gastrocnemius (CCC: 0.37; P < 0.0006). Compared with MRI, panoramic ultrasound demonstrated high accuracy in detecting quadriceps atrophy and hypertrophy (sensitivity: 73.7%; specificity: 74.2%) and gastrocnemius atrophy (sensitivity: 83.1%) and low accuracy in detecting gastrocnemius hypertrophy (specificity: 33.0%).ConclusionsPanoramic ultrasound imaging is a valid tool for monitoring quadriceps muscle atrophy and hypertrophy and for detecting gastrocnemius atrophy.

Assessment of passive muscle elongation using Diffusion Tensor MRI: Correlation between fiber length and diffusion coefficients.

In this study we investigated the changes in fiber length and diffusion parameters as a consequence of passive lengthening and stretching of the calf muscles. We hypothesized that changes in radial diffusivity (RD) are caused by changes in the muscle fiber cross sectional area (CSA) as a consequence of lengthening and shortening of the muscle. Diffusion Tensor MRI (DT-MRI) measurements were made twice in five healthy volunteers, with the foot in three different positions (30° plantarflexion, neutral position and 15° dorsiflexion). The muscles of the calf were manually segmented on co-registered high resolution anatomical scans, and maps of RD and axial diffusivity (AD) were reconstructed from the DT-MRI data. Fiber tractography was performed and mean fiber length was calculated for each muscle group. Significant negative correlations were found between the changes in RD and changes in fiber length in the dorsiflexed and plantarflexed positions, compared with the neutral foot position. Changes in AD did not correlate with changes in fiber length. Assuming a simple cylindrical model with constant volume for the muscle fiber, the changes in the muscle fiber CSA were calculated from the changes in fiber length. In line with our hypothesis, we observed a significant positive correlation of the CSA with the measured changes in RD. In conclusion, we showed that changes in diffusion coefficients induced by passive muscle stretching and lengthening can be explained by changes in muscle CSA, advancing the physiological interpretation of parameters derived from skeletal muscle DT-MRI.

Non–Weight-Bearing and Weight-Bearing Ultrasonography of Select Foot Muscles in Young, Asymptomatic Participants: A Descriptive and Reliability Study

ObjectiveThe primary aim of this study was to determine the reliability of diagnostic ultrasound imaging for select intrinsic foot muscles using both non–weight-bearing and weight-bearing postures. Our secondary aim was to describe the change in muscle cross-sectional area (CSA) and dorsoplantar thickness when bearing weight. MethodsAn ultrasound examination was performed with a linear ultrasound transducer operating between 9 and 12 MHz. Long-axis and short-axis ultrasound images of the abductor hallucis, flexor digitorum brevis, and quadratus plantae were obtained in both the non–weight-bearing and weight-bearing postures. Two examiners independently collected ultrasound images to allow for interexaminer and intraexaminer reliability calculation. The change in muscle CSA and dorsoplantar thickness when bearing weight was also studied. ResultsThere were 26 participants (17 female) with a mean age of 25.5 ± 3.8 years and a mean body mass index of 28.0 ± 7.8 kg/m2. Inter-examiner reliability was excellent when measuring the muscles in short axis (intraclass correlation coefficient >0.75) and fair to good in long axis (intraclass correlation coefficient >0.4). Intraexaminer reliability was excellent for the abductor hallucis and flexor digitorum brevis and ranged from fair to good to excellent for the quadratus plantae. Bearing weight did not reduce interexaminer or intraexaminer reliability. All muscles exhibited a significant increase in CSA when bearing weight. ConclusionsThis is the first report to describe weight-bearing diagnostic ultrasound of the intrinsic foot muscles. Ultrasound imaging is reliable when imaging these muscles bearing weight. Furthermore, muscle CSA increases in the weight-bearing posture.