Medicine and Science in Sports and Exercise最新文献

Introduction: Single-joint knee extension (KE) and multi-joint leg press (LP) are commonly used exercises to train the quadriceps femoris (QF), the largest muscle group in humans. However, their comparative effectiveness for inducing QF hypertrophy remains unclear. Furthermore, the specific muscles hypertrophied by LP are not well characterized. This study compared the hypertrophic effects of KE and LP on the QF and other lower-limb muscles.

Methods: Seventeen untrained adults performed KE with one leg and LP with the contralateral leg at 70% of one-repetition maximum, 10 reps/set, 5 sets/session, 2 sessions/week for 12 weeks. MRI was used to assess pre- and post-training muscle volumes of 17 individual muscles, including the four QF heads, gluteus muscles, hamstrings, and adductors.

Results: Muscle volumes of the individual and whole QF significantly increased in both conditions ( P ≤ 0.026), except for the rectus femoris in the LP condition ( P = 0.379). Rectus femoris volume gains were greater for KE than LP (+13.2% vs. +1.1%, P ≤ 0.001), but gains in the vasti muscles (+5.0-7.2% vs. +4.4-6.2%) and whole QF (+7.1% vs. +4.9%) were comparable between conditions ( P ≥ 0.319). LP, but not KE, increased volumes of the gluteus maximus (+15.4%) and the adductor magnus (+6.2%) ( P ≤ 0.001). A follow-up experiment using surface electromyography showed that muscle excitation patterns during KE and LP generally mirrored the between-condition hypertrophic differences and similarities observed after the training intervention.

Conclusions: LP induces significant hypertrophy in the gluteus maximus and adductor magnus while producing similar vasti and overall QF growth as KE, indicating that LP is a highly time-efficient exercise. However, KE is essential for effectively targeting the rectus femoris, which may have clinical relevance given its high susceptibility to strain injuries.

Introduction: This study aimed to investigate the effect of downhill running on mitophagic flux and autophagosome-lysosome fusion in rat soleus muscle.

Methods: Sprague-Dawley rats were trained on a treadmill at a speed of 16 m·min-1 and a decline of -16° for 90 min, and the soleus muscle was sampled at 0 h, 12 h, 24 h, 48 h, and 72 h after exercise. Mitochondrial ultrastructural changes were observed by using a transmission electron microscope. Protein levels of Cathepsin D (CTSD), Vacuolar H+-ATPase (V-ATPase), mitochondrial respiratory complex Ⅰ (NDUFB8), complex Ⅲ (UQCRC2), and microtubule-associated protein 1 light chain 3 (LC3) were determined by Western blot. Mitochondria co-localizations with LC3 and lysosomal-associated membrane protein 2 (LAMP2), syntaxin 17 (STX17) co-localizations with LC3, LAMP2, SNAP29, and VAMP8, as well as the SNAP29 co-localizations with VAMP8, were measured by immunofluorescence. To assess mitophagic flux in vivo, colchicine or saline was injected intraperitoneally 3 days before exercise, and the protein expression of mitochondrial LC3-Ⅱ was detected by Western blot.

Results: After downhill running, mitochondrial structure appeared to be abnormal and contained autophagosomes and autophagolysosomes. The expression levels of CTSD, V-ATPase, and mitochondrial LC3, as well as the co-localizations of STX17 with LC3 and SNAP29 were significantly higher, whereas the expression levels of mitochondrial NDUFB8, UQCRC2, and LAMP2, along with the co-localizations of STX17 with LAMP2 and VAMP8 were significantly lower than those in the control group. Specifically, mitochondrial LC3-Ⅱ flux was significantly lower following downhill running.

Conclusions: A bout of downhill running may block mitophagic flux by impairing mitophagosome-lysosome fusion, which is accompanied by increased recruitment of STX17 and SNAP29 to autophagosome and reduced co-localizations of STX17 and SNAP29 with lysosomal VAMP8.

Purpose: This study aimed to assess: 1) the concurrent validity between critical power (CP) and the corrected power output at the respiratory compensation point (PORCP) and between W' and the quantity of energy depleted above PORCP (W'mod-SRS) in a modified Step-Ramp-Step (mod-SRS) protocol; 2) the test-retest reliability of endurance variables derived from a mod-SRS protocol.

Methods: Twelve trained male triathletes (31 ± 6 yr, 67.9 ± 7.1 mL.min-1.kg-1) performed i) a SRS protocol, ii) 4 to 5 severe-intensity Constant-Work Rate (CWR) trials, iii) two mod-SRS protocols (test/re-test) and iv) a heavy-intensity CWR trial. CP and W' were computed using a "best individual fit" approach. PORCP was corrected appropriately while W'mod-SRS was computed as the energy depleted above PORCP. Test-retest reliability was assessed with the intraclass correlation coefficient (ICC), the standard error of measurement (SEM) and the coefficient of variation (CV%).

Results: CP was higher than PORCP in both trials (bias = 19 ± 19 W and 17 ± 20 W, p = 0.019 and 0.045). W' and W'mod-SRS were similar between trials (bias = -2.8 ± 7.9 kJ and -5.4 ± 8.8 kJ, p = 0.735 and 0.173). Test-retest reliability was moderate for W'mod-SRS (ICC = 0.66, SEM = 3.0 kJ, CV = 11.6%) and high for V̇O2peak, GET, RCP and their associated PO values (ICCs = 0.85-0.95, SEMs = 68-184 mL.min-1 and 7-8W, CVs = 2.1-3.7%).

Conclusions: The mod-SRS protocol reliably measures V̇O2peak, GET and RCP. Corrected PORCP systematically underestimated CP, which consequently impacts computation of W' using a mod-SRS protocol. The design of the protocol may allow a more complete depletion of energy available above RCP while still eliciting V̇O2peak.

Purpose: Investigate the accuracy of three approaches to estimate KEM deficits using outputs from force plate and two-dimensional position data to identify individuals with surgical limb KEM deficits during a bilateral squat.

Methods: Forty individuals post-ACLr performed bilateral squats. Kinematic and ground reaction force (GRF) data were collected via 3D motion capture system and tri-axial force plates. Surgical limb deficits were calculated using limb symmetry index (LSI: non-surgical/surgical) at peak knee flexion. Gold standard KEM was calculated using inverse dynamics. Vertical GRF was considered alone, and together with the center of pressure (COP) position to estimate deficits in GRF, and GRF-COP Approaches. Vector Approach used the product of vertical GRF and moment arm calculated using vertical and anterior/posterior GRF, COP and knee position in trigonometric equations. Separate linear regression and ICC(2,k) examined concurrent validity between gold standard LSI and LSI from GRF, GRF-COP, and Vector Approaches. Specificity and sensitivity (LSI threshold ≥ 0.85) determined diagnostic accuracy.

Results: GRF, GRF-COP, and Vector LSI's predicted gold standard LSI (R² = 0.56, 0.74, and 0.85 respectively) with ICC(2,k) 0.49, 0.92, and 0.96; sensitivity of 72.2%, 94.4%, 100%, and specificity of 100%, 50%, 100%, respectively.

Conclusions: Vertical GRF alone is not adequate to detect KEM deficits. Additional force plate and two-dimensional position data (COP position and moment arm) can strengthen predictive ability and diagnostic accuracy, supporting translation of these variables into commercial products to enhance clinical assessments.

Purpose: This study aimed to examine whether individuals engaging in high-load resistance training (RT) make any exercise modifications during the first trimester of pregnancy, and describe pelvic floor health, fertility history, and obstetrical characteristics.

Methods: Individuals <20 weeks' gestation who regularly engaged in RT during the first trimester were recruited and completed surveys related to preconception and first trimester pelvic health, fertility, menstrual health, relative energy deficiency in sport, and exercise behaviors. Training logs from three months preconception, until 12 weeks of gestation were obtained from a subset of individuals.

Results: 359 participants, mean age 32.3 years (+/- 3.6 years), completed surveys. From preconception to the first trimester, the frequency of training decreased (4.8 days +/- 1.0 days pre-pregnancy vs 4.0 +/-1.3 days in first trimester, t= 11.45, p<0.01). Most individuals continued Olympic weightlifting (n=127/159, 80%) and core exercises (n=214/234, 92%), with over half increased or maintained the load of RT (n=126/203, 62%). Fatigue and nausea reportedly impacted exercise behaviour in 77% of participants. Rates of previous miscarriage were similar to the general population. Only 15% of participants were given counselling on exercise through miscarriage (10/68 participants). Ten individuals (3%) reported a miscarriage during enrolment in the current study. Pelvic floor complaints during exercise reduced significantly from preconception to trimester one, irrespective of whether training load was reduced or maintained. Forty-one athletes provided preconception and pregnancy training logs. In this subset of athletes, their working load was maintained from preconception across the first trimester at >75% of estimated one-repetition maximums.

Conclusions: Continued participation of RT in the first trimester was well tolerated by those participating in RT preconception.

Purpose: Determine whether moderate-altitude residents (MAR, 1,200 m) experience less AMS than low-altitude residents (LAR) following active or passive ascent to HA (3,600 m).

Methods: 78 Soldiers (mean±SD; age=26±5yr; women=8) were tested at their baseline residence at 331 m (LAR; n=41) or 1,200 m (MAR; n=37), transported to Taos, NM (2,845 m), hiked (n=39) or were driven (n=39) to 3,600 m and stayed for 4 days. AMS was assessed using the Environmental Symptoms Questionnaire twice on day 1 (HA1), five times on days 2 and 3 (HA2, HA3) and once on day 4 (HA4). Daily peak cerebral factor score (AMS-C) was recorded; if AMS-C was ≥ 0.7 individuals were considered sick that day.

Results: Ascent condition (active vs. passive) did not demonstrate a significant main or interaction effect on AMS. The MAR vs. LAR experienced lower AMS incidence on HA1 (16% vs. 44%, p=0.008) and HA2 (19% vs. 39%, p=0.05), similar incidence on HA3 (14% vs. 29%, p=0.08) and lower incidence on HA4 (0% vs. 17%, p=0.007). AMS-C was lower in MAR vs. LAR on HA1 (0.40±0.49 vs. 0.74±0.86, p=0.04), HA2 (0.30±0.34 vs. 0.86±0.88, p=0.001), HA3 (0.30±0.36 vs. 0.56±0.69, p=0.03) and HA4 (0.09±0.14 vs. 0.35±0.58, p=0.01). MAR exhibited an approximately 3-fold reduction in the odds of developing AMS at HA1 (odds ratio (OR)=0.25, p=0.01), HA2 (OR=0.37, p=0.05) and HA3 (OR=0.38, p=0.09) compared to LAR.

Conclusions: Residence at 1,200 m induces a 3-fold reduction in the odds of developing AMS following rapid ascent to 3,600 m.

Team physicians may be called upon to treat adolescent athletes, defined in this document as those in the range of 12-18 yr of age. Many are involved in school-based, intramural, or specialized sports participation and/or training, potentially resulting in injury and/or illness. Specialized treatments may be necessary due to growth and development of the adolescent. Additionally, psychological factors in this age group may play an important role in sports participation, emotional well-being, and injury rehabilitation. While many children younger than 12 yr of age are active in sports participation, their medical and musculoskeletal concerns are not included in the scope of this consensus statement. The healthcare team must stay educated and knowledgeable regarding potential challenges to individuals participating safely in sport. All healthcare professionals should provide quality care, free from discrimination and specific to the needs of every unique individual. Ensuring access to care, fostering welcoming sporting environments, and recognizing the distinct challenges faced by underrepresented populations will reduce healthcare disparities and improve safe participation across all sports.

Purpose: This study aimed to develop a musculoskeletal-environment interaction model to reconstruct the dynamic-interaction process in skiing.

Methods: This study established a skier-ski-snow interaction model that integrated a 3D full-body musculoskeletal model, a flexible ski model, a ski boot model, a ski-snow contact model, and an air resistance model. An experimental method was developed to collect kinematic and kinetic data using inertial measurement units, GPS, and plantar pressure measurement insoles, which were cost-effective and capable of capturing motion in large-scale field conditions. The ski-snow interaction parameters were optimized for dynamic alignment with snow conditions and individual turning techniques. Forward-inverse dynamics simulation was performed using only the skier's body segment kinematics as the model input, leaving the pelvis's translational degrees of freedom relative to a fixed reference frame unconstrained. The model's effectiveness was verified by comparing the simulated results with experimental GPS and insole force data. A forward-muscular inverse-skeletal framework was used to estimate muscle activations.

Results: The agreement between simulated ski-snow contact forces and measured insole forces showed a correlation coefficient of 0.94, with a mean error of -0.022 ± 0.186 N per body weight (mean ± SD), and the error between the predicted motion trajectory and the GPS data was 0.02 ± 0.07 m. Kinematic and kinetic parameters extracted from skiers of different skill levels enabled quantitative evaluation of skiing performance.

Conclusions: The skier-ski-snow interaction model, combined with the ski-snow interaction parameter optimization, enabled the characterization of skiing characteristics across varied snow conditions and different turning techniques (such as carving and skidding). Our research advanced the understanding of alpine skiing dynamics by enabling the identification of skill-dependent kinetic patterns, thereby providing insights to enhance performance.

Introduction: In patients with amnestic mild cognitive impairment (aMCI), cerebrovascular impedance modulus (Z) was higher than in cognitively normal peers, which is associated with brain hypoperfusion. While one year of moderate-to-vigorous aerobic exercise training (AET) reduced Z in cognitively normal older adults, the effects of AET on aMCI remain unknown.

Methods: Seventy patients with aMCI were randomized into one year of AET (N=31) or stretching and toning (SAT, N=39). At baseline, midpoint (6-month), and trial completion (12-month), Z was assessed using transfer function analysis between carotid arterial pressure (CAP) and cerebral blood flow (CBF) velocity measured simultaneously via applanation tonometry and transcranial Doppler in the middle cerebral artery (MCA), respectively. Total CBF was measured as the sum of the bilateral internal carotid and vertebral arterial flow via duplex ultrasonography.

Results: The AET group exhibited gradual, significant reductions in Z at 6 months ( p = 0.008 vs. baseline) and 12 months ( p < 0.001 vs. baseline; p < 0.001 vs. 6 months). In the SAT group, although Z decreased during the first 6 months ( p < 0.001 vs. baseline), it was maintained over the following 6 months. Repeated-measures correlation analyses revealed inverse relationships between Z and total CBF as well as cerebrovascular conductance (CVC) in the AET group (r rm = -0.503, p = 0.008; r rm = -0.404, p = 0.037, respectively), but not in the SAT group. In exploratory sex-stratified analyses, women exhibited continued reductions in Z across 12 months regardless of training modality, whereas men demonstrated a plateau after 6 months.

Conclusions: These findings suggest that in patients with aMCI, AET reduces Z, which is associated with higher brain perfusion and cerebrovascular conductance. Sex-stratified analyses further suggested that women may experience greater improvements in Z than men across one year of training.