Medicine and Science in Sports and Exercise最新文献

Purpose: Blood-brain barrier (BBB) dysfunction is implicated in various neurodegenerative diseases, including Alzheimer's disease and frontotemporal dementia. Over the past decades, numerous studies have suggested that exercise can mitigate neurodegenerative processes by improving mitochondrial function. Recently, we demonstrated that exercise could reverse hippocampus-associated memory deficits and reduce BBB leakage in a modified two-kidney, one-clip (2K1C) hypertensive animal model. Based on these findings, we hypothesize that exercise restores BBB integrity in hypertensive animal models.

Methods: Hypertension was induced in C57BL/6 mice via 2K1C surgery. After 3 wk of hypertension induction, mice underwent moderate-intensity treadmill exercise for 5 wk. Subsequently, brain tissues were collected for immunofluorescence staining and immunoblotting analyses to assess changes in BBB structure and mitochondria-related protein expression.

Results: Exercise restored hypertension-induced reductions in blood vessel density within the hippocampus. Additionally, it repaired BBB structural impairments, as evidenced by increased levels of Claudin-5 colocalization with blood vessels, enhanced perivascular astrocyte levels, and improved perivascular AQP-4 protein expression. An immunoblotting analysis revealed that exercise upregulated the PGC-1α/Nrf1/UCP-2 pathway in the 2K1C hypertensive model. However, exercise did not significantly affect Drp-1 expression.

Conclusions: Exercise alleviates BBB leakage by restoring structural integrity to the BBB. These improvements may be mediated through the enhancement of mitochondrial biogenesis.

Purpose: The aim of the study was to describe trends, characteristics, and mortality associations of U.S. adults unable to do aerobic leisure-time physical activity (LTPA) from 1998 to 2018.

Methods: We used data from 21 U.S. National Health Interview Survey annual updates. Logistic binary regressions were used to estimate odds ratios (OR) and Cox proportional regression models to estimate hazard ratios (HR). People unable to do aerobic LTPA was self-reported.

Results: From a total of 621,499 participants pooled, 10,554 (1.70%) were unable to do PA. Adults who were older than 65 yr (OR = 14.37, 95% confidence interval [CI] = 12.69-16.28), unemployed (OR = 15.61, 95% CI = 14.20-17.17), reported a bad self-rated health (OR = 45.69, 95% CI = 39.52-52.83), and had limitations with instrumental activities of the daily living (OR = 16.51, 95% CI = 15.68-17.38) had a higher risk of being unable to do aerobic LTPA. During a mean follow-up time of 10.36 yr, 5137 participants (50.44%) who were unable to do aerobic LTPA died. They had a higher mortality risk for all-cause (HR = 1.23, 95% CI = 1.18-1.28) mortality compared with the participants who were able to do aerobic LTPA. Adults unable to do aerobic LTPA had an increased risk of all-cause mortality (HR = 1.13, 95% CI = 1.09-1.19) than those who were able but did not perform aerobic LTPA.

Conclusions: U.S. adults unable to perform aerobic LTPA showed a higher risk of all-cause mortality compared with adults who were able to perform aerobic LTPA, and even compared with those who were physically inactive.

Purpose: We sought to evaluate the effect of intensive physical training on left ventricular (LV) hemodynamic forces (HDF) in athletes.

Methods: Forty professional endurance athletes were evaluated at the beginning of their training cycle (off-season) and after a period of aerobic isotonic dynamic exercise (peak training period) using cine cardiac magnetic resonance (CMR). Images were analyzed off-line using dedicated software. LV HDF for the whole cardiac cycle and the different cardiac phases were measured. Standard statistics were used to compare off-season and peak training period values.

Results: The average sport experience was 11 ± 7 yr. There were no differences in LV volumes, stroke volume, LV ejection fraction, and LV mass between off-season and peak training CMR. Similarly, there were no changes induced by physical training in the strain parameters. Physical training induced a significant increase of the longitudinal HDF (18.7 vs 21.2, P = 0.023) and an increase of the transverse HDF (3.4 vs 4.0, P = 0.048) throughout the entire heartbeat. After physical training, the peak values and the hemodynamic work (expressed as area under the curve) of the first part of the systole were significantly higher compared with off-season values (63.9 vs 53.9 ( P = 0.034); 4.67 vs 3.79 ( P = 0.015), respectively). The difference in the elastic rebound between off-season and peak training (-0.22 vs -0.37) did not reach statistical significance ( P = 0.056).

Conclusions: Intense physical training induces an increase in LV HDF throughout the entire heartbeat, independent from geometric cardiac remodeling. The first part of the systole is the phase of the cardiac cycle that is mostly improved by intense physical training.

Purpose: This study investigated the effects of a 6-wk eccentrically biased training intervention between Romanian deadlift (RDL) and Nordic hamstring exercises (NHE) on regional hamstring muscle architecture and morphology.

Methods: Participants were randomly allocated to an RDL or NHE intervention group and trained twice per week for 6 wk followed by a 2-wk detraining period. Biceps femoris long head (BFlh) architecture (fascicle length (FL) and pennation angle (PA)) and muscle thickness (MT) were measured using extended-field-of-view ultrasound. Anatomical cross-sectional areas (ACSA) of BFlh, semimembranosus, and semitendinosus were also assessed via ultrasound. Muscle architecture and morphology were measured proximally, in the middle, and distally along the thigh. Separate linear mixed-effects models were run for each outcome.

Results: Thirty-two healthy participants (15 females, 17 males) aged 20.8 (0.9) yr were enrolled and allocated to RDL ( n = 16) or NHE ( n = 16) groups. Following the intervention, BFlh FL increased (0.80 (0.6-1.0) cm (9%), P < 0.001), whereas PA decreased uniformly across all regions (-1.2° (-1.5° to -0.9°) (10%), P < 0.001) and MT did not change ( P = 0.29). Both BFlh FL and PA returned to baseline after detraining. No differences were observed between groups for changes in FL ( P = 0.55), PA ( P = 0.74), or MT ( P = 0.48). Hamstrings ACSA increased after the intervention (0.78 cm 2 (0.45-1.11 cm 2 ) (10%), P < 0.001) and remained elevated after detraining. There were no significant differences in ACSA between groups after the intervention ( P = 0.60).

Conclusions: Changes in FL, PA, and ACSA are consistent between an eccentrically biased RDL and NHE intervention. These findings provide practitioners choice in exercise selection for eliciting adaptations relevant to hamstring injury prevention.

Purpose: This study aimed to 1) describe perinatal changes in physical activity (PA), physical fitness (PF), and body composition (BC) and 2) investigate prospective associations between PA and PF, and between PF and BC in metabolically high-risk women with gestational diabetes mellitus (GDM).

Methods: This secondary analysis of the MySweetheart trial included 211 women with GDM. Outcomes were measured at 24 to 32 wk of gestational age (GA) and at 1 yr postpartum. Physical activity was measured using accelerometer and BC with bioelectrical impedance analysis (fat mass [FM], fat-free mass [FFM]) or dual-energy X-ray absorptiometry (FM, visceral adipose tissue [VAT], lean mass [LM]; postpartum only). Regarding PF, handgrip strength and cardiorespiratory fitness (CRF) were assessed, the latter using the Chester step test to estimate the maximal oxygen uptake (V̇O 2max ). Models were adjusted for sociodemographic variables and BMI where applicable.

Results: Between pregnancy and the postpartum, sedentary time decreased ( P < 0.001), whereas all PA intensities increased (all P < 0.001). CRF and handgrip strength did not change (both P ≥ 0.07), while FM and FFM decreased (both P < 0.001). Greater overall PA and moderate to vigorous PA during pregnancy were associated with better CRF and handgrip strength at 1 yr postpartum in unadjusted models only ( P < 0.05). Higher V̇O 2max was associated with lower FM and VAT, whereas higher handgrip strength was related to higher LM and FFM at 1 yr postpartum (all P < 0.001), before and after adjustments.

Conclusions: In high-risk women with GDM, higher PA during pregnancy correlated with greater PF at 1 yr postpartum only in the unadjusted, but not in the adjusted analyses. Higher PF levels were related to improved BC, highlighting their importance in the perinatal period.

Purpose: Dietary nitrate (NO 3- ) supplementation has been shown to improve skeletal muscle contractile function and reduce fatigue, potentially due to alterations in skeletal muscle Ca 2+ handling/sensitivity. Because aging muscle can have impaired Ca 2+ handling, the aim of the study was to evaluate the effects of dietary NO 3- supplementation on muscle contractile properties in young and older adults.

Methods: Eleven older (69 ± 4 yr, O) and 11 young (26 ± 2 yr, YG) adults consumed either NO 3- -rich beetroot juice (BR) or placebo (PLA), for 7 d. After supplementations, plantar flexors of dominant leg were evaluated as follow: a) maximal voluntary isometric contraction (MVIC), b) potentiated single twitches (Tw pot ) and double twitches electrical stimulations at the frequency of 100 Hz (Db 100 ) on the tibial posterior nerve, c) a fatigue isometric (70% of MVIC) test until exhaustion. The force-frequency relationship was assessed with trains of electrical pulses across a wide range of frequencies on the muscle belly of the nondominant leg.

Results: BR supplementation increased plasma [NO 3- ] and nitrite [NO 2- ] in both O and YG compared with PLA (more than sevenfold; all P ≤ 0.02). No changes were observed in MVC, Tw pot , and Db 100 force after BR compared with PLA in both YG and O. Only in O, Db 100 area under the curve (-7 ± 6 N·s change from PLA) and half relaxation time (-0.05 ± 0.06 s change from PLA) were significantly reduced, and time to exhaustion (+32 ± 43 s change from PLA) was significantly longer (all P < 0.02) after BR. In O, BR also significantly increased submaximal force produced by trains of electrical pulses ( P < 0.001).

Conclusions: NO 3- supplementation positively affects muscle contractile proprieties, submaximal electrically evoked force production, and fatigue resistance in older adults, whereas these positive results were not found in young.

Purpose: Stationary cycling is essential in rehabilitation programs for various patient groups, such as knee osteoarthritis and cruciate ligament injuries and reconstruction. The study aimed to measure in vivo the 3D rigid-body and articular surface kinematics of the knee and the patellar tendon orientations during stationary cycling and isolated flexion-extension exercise in healthy young adults using a model-based tracking approach with dual-plane fluoroscopy.

Methods: Ten healthy left knees were imaged by computed tomography and magnetic resonance imaging to reconstruct subject-specific volumetric bone-cartilage models. The 3D rigid-body and articular surface kinematics and patellar tendon angles during stationary cycling and isolated knee flexion-extension exercise were measured in vivo using a dual-plane fluoroscopy with a voxel-based registration method, compared between tasks and between power and recovery phases.

Results: Significant differences in the rigid-body and surface kinematics and patellar tendon orientations were found between the power and recovery phases and between the power phase and isolated knee extension. Compared with the recovery phase, the power phase showed significantly greater external rotations, adductions, and posterior translations for flexions greater than 45° ( P < 0.05) with significantly more posterior medial and lateral contact positions for flexion angles less than 45° ( P < 0.05) and more vertical patellar tendon orientations for flexion angles lesser than 60° ( P < 0.05).

Conclusions: The contact locations and loads on the posterior half of the tibial articular surface during the first half of the power phase indicate that stationary cycling as a daily and rehabilitative exercise is safe for people with anterior medial knee osteoarthritis.

Purpose: The cardiometabolic benefits of replacing sedentary time with light-intensity physical activity (LIPA) are unclear. We studied the associations of hypothetically reallocating sedentary time toward LIPA with changes in cardiometabolic risk factors using thigh-worn accelerometery. We also explored whether reallocation effects differed across subgroups with low, moderate, and high sedentary time and compared proportionally similar reallocations to either LIPA or moderate-to-vigorous physical activity.

Methods: We assessed physical behaviors across 8 consecutive days using thigh-worn accelerometers among adults from the Nijmegen Exercise Study. Multiple cardiometabolic risk factors were assessed and categorized as 1) anthropometrics, 2) cardiovascular biomarkers, and 3) glucose metabolism. Reallocation effects were estimated for each cardiometabolic risk factor using compositional isotemporal substitution models adjusted for confounders. Analyses were repeated in sedentary time subgroups, that is, <8.5, 8.5-10, and >10 h·d -1 .

Results: We included 1041 participants (64 (standard deviation 11) yrs; 39.5% female). Reallocating sedentary time toward LIPA was associated with improvements in anthropometrics, some cardiovascular biomarkers, and glucose metabolism; for example, replacing 60 min·d -1 of sedentary time with LIPA was associated with improvements in body mass index (-0.28 (-0.42 to -0.13) kg·m -2 ), estimated glomerular filtration rate (0.68 (0.15 to 1.20) mL·min -1 ·1.73m -2 ), and glucose (-0.05 (-0.08 to -0.03) mmol·L -1 ). Trends suggested that reallocation benefits were strongest in those with >8.5 h·d -1 of sedentary time. Proportionally similar replacements of sedentary time with either LIPA or moderate-to-vigorous physical activity were associated with similar cardiometabolic benefits.

Conclusions: Reallocation of sedentary time to LIPA was associated with improvements in cardiometabolic risk factors, predominantly in anthropometrics and glucose metabolism, with greater benefits in the most sedentary individuals. Time reallocation from sedentary time to LIPA may be an effective and arguably feasible strategy to improve population-wide cardiometabolic health.

Purpose: Following anterior cruciate ligament reconstruction (ACLR), individuals present with significant and persistent deficits in surgical knee biomechanics during running. Little is known regarding the role of the hip and ankle in compensating for these knee-specific deficits. The purpose of this study was to characterize how limb (surgical and nonsurgical), time postoperatively (3.5-7 months [EARLY], 8-13 months [LATE]), and running speed influence lower extremity joint-specific and total work during running post-ACLR.

Methods: Fifty-six Division I collegiate athletes post-ACLR (EARLY: n = 41; LATE: n = 42; both: n = 27) completed running analyses at 2.68, 2.95, 3.35, 3.80, and 4.47 m·s -1 or up to their maximum comfortable speed. Linear mixed effects models assessed the influence of limb, speed, time post-ACLR, and their interactions on hip, knee, ankle, and total negative work and positive work.

Results: Surgical limb hip positive work was greater (0.044 J·kg -1 [95% CI = 0.015-0.074], P < 0.001) than the nonsurgical limb EARLY. Surgical limb ankle negative (-0.054 J·kg -1 [-0.093 to -0.015], P = 0.003) and positive work (-0.115 J·kg -1 [-0.168 to -0.063], P < 0.001) were less than the nonsurgical limb EARLY. Surgical limb knee negative (EARLY: -0.339 J·kg -1 [-0.382 to -0.296], P < 0.001; LATE: -0.222 J·kg -1 [-0.265 to -0.180], P < 0.001) and positive work (EARLY: -0.214 J·kg -1 [-0.246 to -0.182], P < 0.001; LATE: -0.142 J·kg -1 [-0.174 to -0.110], P < 0.001) were less than the nonsurgical limb. Total negative work and positive work followed the same pattern as the knee.

Conclusions: Athletes post-ACLR exhibited greater hip positive work and lesser ankle positive work and negative work during running of the surgical limb EARLY, which resolved LATE. Both knee and total negative work and positive work of the surgical limb were substantially less than the nonsurgical limb, which improved from EARLY to LATE, but between-limb asymmetries remained.