Medicine and Science in Sports and Exercise最新文献

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.

Introduction/purpose: This study examined the relationship between lower extremity muscle volumes and countermovement jump (CMJ) performance in 207 (43 female, 164 male) NCAA Division I collegiate basketball, football, hockey, and soccer athletes. The primary aim was to determine which combination of lower extremity muscle volumes was most strongly associated with CMJ performance across a large subset of high-level college athletes.

Methods: Athletes underwent bilateral MRI scans, and muscle volumes were quantified using machine-learning-based auto-segmentation. CMJ height (cm) and peak power (W/kg) were measured using dual force plates. Backward selection regression analyses determined muscle combinations that best explained variance in jump performance after adjusting for sex and sport.

Results: Vastus lateralis muscle volume was related to both jump height (β = 0.36, p < 0.01) and peak power (β = 0.41, p < 0.01). In addition to the vastus lateralis, the jump height model retained rectus femoris, and the peak power model retained soleus, gluteus medius, adductor magnus, and biceps femoris long head. The differing muscle candidates in the two models likely reflect the distinct features of each CMJ metric: jump height reflects force over time (impulse, N·s) while peak power reflects the rapid generation of force (N·m/s). Sport-specific differences emerged, with hockey and football athletes displaying greater jump heights and generating greater peak power when compared to basketball players. Male athletes outperformed females in both jump metrics.

Conclusions: These findings, derived from over 200 NCAA Division I athletes, highlight the crucial role of the quadriceps in CMJ performance in high‑level athletes. Strength and conditioning and rehabilitation programs may consider targeting quadriceps hypertrophy to improve vertical jump performance.

Purpose: Physical activity (PA) and sedentary behavior (SB) are associated with many diseases, including Alzheimer's disease and all-cause dementia. However, the specific biological mechanisms through which PA protects against disease are not entirely understood. This study aims to address this gap, with a specific focus on all-cause dementia.

Methods: We first assessed the conventional observational associations of three self-reported and three device-based PA/SB measures with circulating levels of 2,911 plasma proteins measured in the UK Biobank (n max =39,160) and assessed functional enrichment of identified proteins. We then used bi-directional Mendelian randomization (MR) to further evaluate the evidence for causal relationships of PA/SB with protein levels. Finally, we performed mediation analyses to identify proteins that may mediate the relationship of PA with incident all-cause dementia.

Results: Our findings revealed 41 proteins consistently associated with all PA measures and 1,027 proteins associated with at least one PA measure. Both conventional observational and MR study designs converged on proteins that appear to increase as a result of PA, including integrins such as ITGAV and ITGAM, as well as MXRA8, CLEC4A, CLEC4M, LPL, and ADGRG2; on proteins that appear to decrease as a result of PA such as LEP, INHBC, CLMP, PTGDS, ADM, OGN, and PI3; and on proteins that are more responsive to high-intensity PA, such as CA14, CA6, CA4, KIT, and ANGPT2. Functional enrichment analyses revealed processes such as cell-matrix adhesion, integrin-mediated signaling, and collagen binding. Finally, GDF15, ITGAV, ITGAM, ITGA11, HPGDS, GFAP, ADM, AHNAK, and DPP4 were among 21 unique proteins found to mediate the relationship of PA with all-cause dementia, implicating processes such as synaptic plasticity, neurogenesis, and inflammation.

Conclusions: Our results provide insights into how PA affects biological processes and protects against dementia, and provide avenues for future research into the health-promoting effects of PA.

Introduction/purpose: There is evidence showing that males have greater reactive hyperemia compared with females. However, females also show less desaturation rate and magnitude during blood flow occlusion compared with males, questioning whether the reduced reactive hyperemia observed in females is a consequence of reduced "ischemic" stimulus.

Methods: We assessed femoral artery conduit artery and skeletal muscle (tibialis anterior) reactive hyperemia in 75 young healthy males ( n = 38) and females ( n = 37). Data were analyzed using different strategies such as i) simple comparisons of indexes of reactive hyperemia of the full cohort without considering tissue desaturation, ii) indexes of reactive hyperemia comparisons between subjects that matched for tissue desaturation, iii) skeletal muscle reactive hyperemia comparisons between males and females from the full cohort by using other proposed methods in the literature, and iv) comparison of skeletal muscle reactive hyperemia between males and females from the full cohort while controlling for desaturation indexes using analysis of covariance (ANCOVA).

Results: Overall, females showed reduced desaturation magnitude (20% ± 6% vs 28% ± 5%, P < 0.001) and near-infrared spectroscopy-derived reperfusion slope (slope 2) (0.8 ± 0.2%·s -1 vs 1.4 ± 0.6%·s -1 , P < 0.001) compared with males. However, in a subset of tissue desaturation-matched participants, reactive hyperemia remained reduced in females compared with males (1.0 ± 0.2 vs 1.3 ± 0.4, P = 0.018). When, tissue desaturation data were controlled by using ANCOVA, this approach was more accurate than other proposed normalizations for assessing skeletal muscle reactive hyperemia in males and females.

Conclusions: Our findings indicate that using proposed normalization models may neglect sex-related differences in reactive hyperemia. However, using ANCOVA to account for differences in desaturation may provide a more accurate approach when comparing skeletal muscle reactive hyperemia between males and females.