Treadmill Running Research Articles

Effects of short-term exercise and endurance training on skeletal muscle mitochondria damage induced by particular matter, atmospherically relevant artificial PM2.5.

This study aimed to investigate the potential of short-term aerobic exercise to mitigate skeletal muscle mitochondrial damage following ambient PM2.5 exposure, and how 12 weeks of endurance training can enhance aerobic fitness to protect against such damage. Twenty-four male C57BL/6 J mice were split into sedentary (SED, n = 12) and endurance training (ETR, n = 12) groups. The ETR group underwent 12 weeks of training (10-15 m/min, 60 min/day, 4 times/week), confirmed by an Endurance Exercise Capacity (EEC) test. Post-initial training, the SED group was further divided into SSED (SED and sedentary, n = 6) and SPE (SED and PM2.5 + Exercise, n = 6). Similarly, the ETR group was divided into EEX (ETR and Exercise, n = 6) and EPE (ETR and PM2.5 + Exercise, n = 6). These groups underwent 1 week of atmospherically relevant artificial PM2.5 exposure and treadmill running (3 times/week). Following treatments, an EEC test was conducted, and mice were sacrificed for blood and skeletal muscle extraction. Blood samples were analyzed for oxidative stress indicators, while skeletal muscles were assessed for mitochondrial oxidative metabolism, antioxidant capacity, and mitochondrial damage using western blot and transmission electron microscopy (TEM). After 12 weeks of endurance training, the EEC significantly increased (p < 0.000) in the ETR group compared to the SED group. Following a one-week comparison among the four groups with atmospherically relevant artificial PM2.5 exposure and exercise treatment post-endurance training, the EEX group showed improvements in EEC, oxidative metabolism, mitochondrial dynamics, and antioxidant functions. Conversely, these factors decreased in the EPE group compared to the EEX. Additionally, within the SPE group, exercise effects were evident in HK2, LDH, SOD2, and GPX4, while no impact of short-term exercise was observed in all other factors. TEM images revealed no evidence of mitochondrial damage in both the SED and EEX groups, while the majority of mitochondria were damaged in the SPE group. The EPE group also exhibited damaged mitochondria, although significantly less than the SPE group. Atmospherically relevant artificial PM2.5 exposure can elevate oxidative stress, potentially disrupting the benefits of short-term endurance exercise and leading to mitochondrial damage. Nonetheless, increased aerobic fitness through endurance training can mitigate PM2.5-induced mitochondrial damage.

Aerobic exercise attenuates high-fat diet–induced renal injury through kidney metabolite modulation in mice

Purpose To investigate the preventive effect of aerobic exercise on renal damage caused by obesity. Methods The mice in the Control (Con) and Control + Exercise (Con + Ex) groups received a standard chow diet for the 21-week duration of the study, while the High-fat diet (HFD) group and High-fat diet + Exercise (HFD + Ex) group were fed an HFD. Mice were acclimated to the laboratory for 1 week, given 12 weeks of being on their respective diets, and then the Con + Ex and HFD + Ex groups were subjected to moderate intensity aerobic treadmill running 45 min/day, 5 days/week for 8 weeks. Results We found that HFD-induced obesity mainly impacts kidney glycerin phospholipids, glycerides, and fatty acyls, and aerobic exercise mainly impacts kidney glycerides, amino acids and organic acids as well as their derivatives. We identified 18 metabolites with significantly altered levels that appear to be involved in aerobic exercise mediated prevention of HFD-induced obesity and renal damage, half of which were amino acids and organic acids and their derivatives. Conclusion Aerobic exercise rewires kidney metabolites to reduce high-fat diet-induced obesity and renal injury.

Can Machine Learning Predict Running Kinematics Based on Upper Trunk GPS-Based IMU Acceleration? A Novel Method of Conducting Biomechanical Analysis in the Field Using Artificial Neural Networks

This study aimed to investigate whether running kinematics can be accurately estimated through an artificial neural network (ANN) model containing GPS-based accelerometer variables and anthropometric data. Thirteen male participants with extensive running experience completed treadmill running trials at several speeds. Participants wore a GPS device containing a triaxial accelerometer, and running kinematics were captured by an 18-camera motion capture system for each trial. Multiple multilayer perceptron neural network models were constructed to estimate participants’ 3D running kinematics. The models consisted of the following input variables: 3D peak accelerometer acceleration during foot stance (g), stance time (s), running speed (km/h), participant height (cm), leg length (cm), and mass (kg). Pearson’s correlation coefficient (r), root mean squared error (RMSE), and relative root mean squared error (rRMSE) showed that ANN models provide accurate estimations of joint/segment angles (mean rRMSE = 13.0 ± 4.3%) and peak segment velocities (mean rRMSE = 22.1 ± 14.7%) at key gait phases across foot stance. The highest accuracies were achieved for flexion/extension angles of the thorax, pelvis, and hip, and peak thigh flexion/extension and vertical velocities (rRMSE &lt; 10%). The current findings offer sports science and medical practitioners working with this data a method of conducting field-based analyses of running kinematics using a single IMU.

Musculoskeletal Health Worsened from Carnitine Supplementation and Not Impacted by a Novel Individualized Treadmill Training Protocol

Introduction: Chronic kidney disease (CKD) negatively affects musculoskeletal health, leading to reduced mobility, and quality of life. In healthy populations, carnitine supplementation and aerobic exercise have been reported to improve musculoskeletal health. However, there are inconclusive results regarding their effectiveness and safety in CKD. We hypothesized that carnitine supplementation and individualized treadmill exercise would improve musculoskeletal health in CKD. Methods: We used a spontaneously progressive CKD rat model (Cy/+ rat) (n = 11–12/gr): (1) Cy/+ (CKD-Ctrl), (2) CKD-carnitine (CKD-Carn), and (3) CKD-treadmill (CKD-TM). Carnitine (250 mg/kg) was injected daily for 10 weeks. Rats in the treadmill group ran 4 days/week on a 5° incline for 10 weeks progressing from 30 min/day for week one to 40 min/day for week two to 50 min/day for the remaining 8 weeks. At 32 weeks of age, we assessed overall cardiopulmonary fitness, muscle function, bone histology and architecture, and kidney function. Data were analyzed by one-way ANOVA with Tukey’s multiple comparisons tests. Results: Moderate to severe CKD was confirmed by biochemistries for blood urea nitrogen (mean 43 ± 5 mg/dL CKD-Ctrl), phosphorus (mean 8 ± 1 mg/dL CKD-Ctrl), parathyroid hormone (PTH; mean 625 ± 185 pg/mL CKD-Ctrl), and serum creatinine (mean 1.1 ± 0.2 mg/mL CKD-Ctrl). Carnitine worsened phosphorous (mean 11 ± 3 mg/dL CKD-Carn; p < 0.0001), PTH (mean 1,738 ± 1,233 pg/mL CKD-Carn; p < 0.0001), creatinine (mean 1 ± 0.3 mg/dL CKD-Carn; p < 0.0001), cortical bone thickness (mean 0.5 ± 0.1 mm CKD-Ctrl, 0.4 ± 0.1 mm CKD-Carn; p < 0.05). Treadmill running significantly improves maximal aerobic capacity when compared to CKD-Ctrl (mean 14 ± 2 min CKD-TM, 10 ± 2 min CKD-Ctrl; p < 0.01). Conclusion: Carnitine supplementation worsened CKD progression, mineral metabolism biochemistries, and cortical porosity and did not have an impact on physical function. Individualized treadmill running improved maximal aerobic capacity but did not have an impact on CKD progression or bone properties. Future studies should seek to better understand carnitine doses in conditions of compromised renal function to prevent toxicity which may result from elevated carnitine levels and to optimize exercise prescriptions for musculoskeletal health.

FNIP-1 Expression in Mice Muscle Negatively Correlated with Myoglobin Level and Endurance Performance on Treadmill Run Test

Previously, FNIP-1 was found to play a critical role in the coupling of mitochondria function to restore ATP. Mitochondria was need to be supplied sufficient oxygen by myoglobin in the myocyte. We proposed that FNIP-1 also regulated myoglobin levels to support endurance performance. This study aimed to investigate whether FNIP-1 expression in muscle was correlated with myoglobin level and endurance performance on the treadmill run test. Male adult balb/c mice performed a run on the treadmill for as long as possible. The duration of running was measured as endurance performance. Its calf muscles were analyzed for myoglobin level and FNIP-1 expression. Lower FNIP-1 expression in calf muscle was found on higher levels of myoglobin and the longer duration of running on a treadmill. The Pearson test showed that the P value was &lt;0.05, which indicated that there was a correlation between FNIP-1 and myoglobin with a score of -0.77, which indicated that there was a negative correlation. The Spearman test also showed that the P value was &lt;0.05, which indicated that there was a correlation between FNIP-1 and endurance performance with a score of -0.70, which indicated that there was a negative correlation. So, FNIP-1 expression negatively correlated with myoglobin level and endurance performance of mice. Further study needs to investigate the FNIP-1 expression in human muscle to look at its correlation with the level of lactate, oxygen saturation (SaO2), oxygen fraction (FiO2), and maximum volume of oxygen uptake (VO2 max). Keywords: FNIP-1, muscle, endurance, myoglobin, healthy lifestyle.

Effects of chronic alcohol intoxication on aerobic exercise-induced adaptations in female mice.

Chronic alcohol intoxication decreases muscle strength/function and causes mitochondrial dysfunction. Aerobic exercise training improves mitochondrial oxidative capacity and increases muscle mass and strength. Presently, the impact of chronic alcohol on aerobic exercise-induced adaptations was investigated. Female C57BL/6Hsd mice were randomly assigned to one of four groups: control sedentary (CON SED; n = 26), alcohol sedentary (ETOH SED; n = 27), control exercise (CON EX; n = 28), and alcohol exercise (ETOH EX; n = 25). Exercise mice had running wheel access for 2 h a day, 7 days a week. All mice were fed either control or an alcohol-containing liquid diet. Grip strength testing and EchoMRI were performed before and after the interventions. After 6 wk, hindlimb muscles were collected for molecular analyses. A subset of mice performed a treadmill run to fatigue (RTF), then abstained from alcohol for 2 wk and repeated the RTF. Alcohol decreased lean mass and forelimb grip strength compared with control-fed mice. Alcohol blunted the exercise-induced increase in muscle mass (plantaris and soleus), type IIa fiber percentage in the plantaris, and run time to fatigue. Mitochondrial markers (Citrate synthase activity and Complex I-IV, COXIV and Cytochrome C protein expression) were increased with exercise regardless of ETOH in the gastrocnemius but not tibialis anterior muscle. Two weeks of alcohol abstinence improved RTF time in ETOH EX but not in ETOH SED. These data suggest that alcohol impairs some exercise-induced adaptations in skeletal muscle, but not all were negatively affected, indicating that exercise may be a beneficial behavior even while consuming alcohol.NEW & NOTEWORTHY Alcohol consumption during an aerobic exercise training period prevented training-induced increases in run to fatigue time and grip strength. Cessation of alcohol allowed for recovery of endurance performance within 2 wk. The worsened exercise performance after alcohol was unrelated to impairments in markers of mitochondrial health. Therefore, some adaptations to exercise training are impaired with alcohol use (endurance performance, muscle growth, and strength), while others remain mostly unaffected (mitochondrial health).

Exercise Inhibits Doxorubicin-Induced Cardiotoxicity via Regulating B Cells.

Doxorubicin is an effective chemotherapeutic agent, but its use is limited by acute and chronic cardiotoxicity. Exercise training has been shown to protect against doxorubicin-induced cardiotoxicity, but the involvement of immune cells remains unclear. This study aimed to investigate the role of exercise-derived B cells in protecting against doxorubicin-induced cardiotoxicity and to further determine whether B cell activation and antibody secretion play a role in this protection. Mice that were administered with doxorubicin (5 mg/kg per week, 20 mg/kg cumulative dose) received treadmill running exercise. The adoptive transfer of exercise-derived splenic B cells to μMT-/- (B cell-deficient) mice was performed to elucidate the mechanism of B cell regulation that mediated the effect of exercise. Doxorubicin-administered mice that had undergone exercise training showed improved cardiac function, and low levels of cardiac apoptosis, atrophy, and fibrosis, and had reduced cardiac antibody deposition and proinflammatory responses. Similarly, B cell pharmacological and genetic depletion alleviated doxorubicin-induced cardiotoxicity, which phenocopied the protection of exercise. In vitro performed coculture experiments confirmed that exercise-derived B cells reduced cardiomyocyte apoptosis and fibroblast activation compared with control B cells. Importantly, the protective effect of exercise on B cells was confirmed by the adoptive transfer of splenic B cells from exercised donor mice to μMT-/- recipient mice. However, blockage of Fc gamma receptor IIB function using B cell transplants from exercised Fc gamma receptor IIB-/- mice abolished the protection of exercise-derived B cells against doxorubicin-induced cardiotoxicity. Mechanistically, we found that Fc gamma receptor IIB, an important B cell inhibitory receptor, responded to exercise and increased B cell activation threshold, which participated in exercise-induced protection against doxorubicin-induced cardiotoxicity. Our results demonstrate that exercise training protects against doxorubicin-induced cardiotoxicity by upregulating Fc gamma receptor IIB expression in B cells, which plays an important anti-inflammatory role and participates in the protective effect of exercise against doxorubicin-induced cardiotoxicity.

Stryd biomechanical parameters as indicators of running economy and performance

The interplay of biomechanical and neuromuscular aspects aids in the conversion of power production in running performance, and when combined with metabolic factors, these aspects may lead to improved running economy (RE). Therefore, the purpose of this study is to determine the association between the Stryd Power Meter foot pod metrics with RE and performance. Fifteen high-caliber male athletes completed two treadmill running sessions. First, RE was determined at 10 and 12 km/h. Second, two all-out efforts of nine and three minute duration were completed. At 10 km/h, the simple and stepwise multiple linear regression analysis revealed that form power (FP) was the best RE predictor (adjusted R2 = 0.464; p = 0.005) followed by vertical oscillation (VO) ( R2 = 0.424; p = 0.005) and ground contact time (GCT) ( R2 = 0.363; p = 0.010). At 12 km/h, such regressions confirmed that GCT was the best RE indicator (adjusted R2 = 0.222; p = 0.043) followed by FP (adjusted R2 = 0.213; p = 0.047). During the nine and three minute all-out effort sessions, GCT was the best performance predictor ( R2 = 0.491; p = 0.002 and R2 = 0.380; p = 0.014, respectively). The biomechanical factors of GCT and FP are good indicators of RE and running performance.

Muscle activity and kinematics during three hamstring strengthening exercises compared to sprinting: A cross-sectional study

Background&#x0D; Sprinting is a crucial task in many sports and remains the major activity during which hamstring muscle injuries occur (Schache et al., 2012). Though the biceps femoris long head predominantly gets injured (Grange et al., 2023), hamstring strengthening exercises frequently seem to activate the semitendinosus more effectively (Bourne et al., 2017). A better understanding of how joint dominance influences activation levels of hamstring muscles may offer more clarity on the appropriate exercise selection in strengthening programs.&#x0D; Purpose&#x0D; This study compared 3 hip-dominant hamstring exercises (the rocker, perpetuum mobile fast and slow; PMfast and PMslow) and the Nordic Hamstring exercise (NHE) on their potential to simulate sprint-like activity and kinematics.&#x0D; Methods&#x0D; Muscle activity of the posterior kinetic chain (mm. biceps femoris, semitendinosus, gluteus maximus and gastrocnemius medialis) was measured with surface electromyography (sEMG) during every exercise and treadmill running at 75% of the individual maximal sprint velocity in 8 male athletes (age: 24.0 years ± SD 2.9; body mass: 76.8 kg ± 7.7; height: 1.79 m ± 0.08). sEMG data was normalized to maximal sprinting. 3D-motion capture was employed to assess hip and knee angles.&#x0D; Results&#x0D; This study revealed higher activity of the hamstrings for the explosive exercises ranging from 63.9% [95%CI: 56.3-71.5%] (rocker) to 49.0% [95%CI: 40.4-57.6%] (PMfast) vs. 34.0% [95%CI: 29.1-38.9%] (NHE) to 32.1% [95%CI: 26.9-37.3%] (PMslow). The rocker especially showed highest hamstring and m. gluteus maximus activity. M. biceps femoris consistently showed higher activity than m. semitendinosus across all exercises in peak (mean difference: 0.16, [95%CI: 0.07-0.26]) and average (mean difference: 0.06, [95%CI: 0.01-0.11]) activity. PMfast, PMslow and NHE demonstrated lower hip flexion angle of peak hamstring activity than the rocker and high-speed running and every exercise showed lower hamstring elongation stress than during high-speed running.&#x0D; Discussion&#x0D; Hamstring activity is comparable to high-intensity treadmill running for NHE and PMslow, and higher for the rocker and PMfast. M. gluteus maximus activity varied, with the rocker and PMfast showing higher activity than in sprinting. All examined exercises demonstrated their peak activity at short hamstring muscle length.&#x0D; What this study adds to the existing knowledge&#x0D; This study generated first data on sprint-specificity of two not yet investigated versions of a unilateral hip thrust. Similar or higher activity than during sprinting and BFlh selectivity was reached through explosive, closed kinetic chain, hip-dominant movement.&#x0D; References&#x0D; Bourne, M. N., Williams, M. D., Opar, D. A., Al Najjar, A., Kerr, G. K., &amp; Shield, A. J. (2017). Impact of exercise selection on hamstring muscle activation. British Journal of Sports Medicine, 51(13), 1021-1028. https://doi.org/10.1136/bjsports-2015-095739&#x0D; Grange, S., Reurink, G., Nguyen, A. Q., Riviera-Navarro, C., Foschia, C., Croisille, P., &amp; Edouard, P. (2023). Location of hamstring injuries based on magnetic resonance imaging: A systematic review. Sports Health, 15(1), 111-123. https://doi.org/10.1177/19417381211071010&#x0D; Schache, A. G., Dorn, T. W., Blanch, P. D., Brown, N. A., &amp; Pandy, M. G. (2012). Mechanics of the human hamstring muscles during sprinting. Medicine &amp; Science in Sports &amp; Exercise, 44(4), 647-658. https://doi.org/10.1249/MSS.0b013e318236a3d2

The order of running shoes and how it influences the perception of effort and comfort

Introduction High performance modern shoes reduce energy expenditure and improve performance, however, these gains may also stem from differences in perceived effort. Humans tend to weigh negative information more heavily than positive information, which could influence perception of effort when different shoes are tested sequentially. This study aimed to determine the existence of negativity bias on different measures of perception when alternating running shoes. Methods Eleven well-trained male athletes [age: 28 ± 6 years, weight: 68 ± 5 kg, height: 179 ± 5 cm, peak oxygen consumption: 65 ± 4 ml O2･kg-1･min-1] performed three lab visits: a familiarization day with an incremental test followed by two experimental days (track and treadmill, in balanced order). On each day, participants performed four sets of two 5-min runs at 16km･h-1 (5-min breaks in-between) alternating between On Cloudrunner (entry-level, EL) and Cloudboom Echo 3 (high-performance, HP). The order of the shoes was changed every set (i.e, EL-HP or HP-EL). After each run, participants reported their perception of effort (both on a 100-mm Visual Analog Scale [VAS] and on a 1-10 Borg Scale) and shoe comfort (VAS). Heart rate and gas exchange were monitored using a chest sensor and a metabolic cart. Differences in ratings between EL-HP and HP-EL were compared using paired t-tests. Results In combined data of track and treadmill, the physiological response and perception of effort were significantly lower while perception of comfort was significantly higher with HP compared to EL. On the treadmill, the absolute value of the change in perceived effort (VAS) was lower for EL-HP compared with HP-EL (0.6 ± 0.5 mm vs. 1.0 ± 0.7 mm, p = 0.013), but not on the track (EL-HP 0.5 ± 0.5 mm vs. HP-EL 0.6 ± 0.3 mm, p = 0.602). Absolute changes of effort (Borg) were neither affected by shoe order on the treadmill (EL-HP 0.7 ± 0.4 pts vs. HP-EL 0.8 ± 0.7 pts, p = 0.699) nor on the track (EL-HP 0.5 ± 0.4 pts vs. HP-EL 0.7 ± 0.6 pts, p = 0.452). Similarly, ratings of shoe comfort were neither affected by shoe order on the treadmill (EL-HP 1.8 ± 1.1 mm vs. HP-EL 1.4 ± 1.0 mm, p = 0.086) nor on the track (EL-HP 1.5 ± 1.1 mm vs. HP-EL 1.6 ± 1.0 mm, p = 0.674). Discussion/Conclusion Changes in perceived effort (VAS) assessed during treadmill running were nearly two times larger when switching from EL to HP than vice-versa, supporting the presence of a negativity bias in this specific condition, which could be related to the higher resolution of VAS scales compared with Borg. Possibly, the lack of negativity bias on the track resulted from an overall reduced rating of effort compared with treadmill, which left less room for differences. These findings suggest that it would be beneficial to include a control shoe worn before and between the tested shoes of interest to mitigate any potential negativity bias in tests when determining perceived effort on a treadmill with different shoes.

Should a 1% gradient be used to equate the metabolic cost between treadmill and overground running?

Introduction&#x0D; Running on a motorized treadmill offers the possibility of precise adjustments in speed as well as more complex monitoring of athletes. On the other hand, the lack of wind resistance compared with outdoor running introduces a possible significant deviation from the expected metabolic cost of running at higher speeds. The literature offers contrasting views on the topic, with older studies suggesting a lower metabolic cost for treadmill running and vice-versa for newer investigations. Nonetheless, a recommendation that treadmills use a 1% inclination gradient to account for the lack of wind resistance remains very influential in the field. We therefore investigated whether cardiorespiratory responses differ between running on a motorized treadmill with a 1% incline compared with running outdoors on a running track at a similar speed.&#x0D; Methods&#x0D; Fourteen highly trained male athletes (age 28 ± 5 years, height 180 ± 6 cm, body mass 70 ± 6 kg and peak oxygen consumption, V̇O2peak, 64 ± 4 mL kg-1･min-1) visited the laboratory on three different occasions, separated at least by 72 h. On the first day, participants performed an incremental running test to determine V̇O2peak and to familiarize themselves with the laboratory settings and equipment. On each of the two subsequent testing days, participants performed, after standardized warm-up, a 5-min run at 14 km･h-1 on either the treadmill (Pulsar It 3P, H/P Cosmos, Germany) or the track, in randomized order. Feedback regarding pacing on the track was given every 200 m. Gas exchange and heart rate were monitored throughout the runs using a portable metabolic cart (Metamax 3B, Cortex, Germany) and a connected heart rate monitor (Polar H10, Polar, Finland). In both conditions, the metabolic cart was carried by the participants using a vest provided by the manufacturer. Comparisons between conditions were performed using paired t-tests. A separate group of 4 individuals performed a set of two runs on the treadmill at 14 km･h-1 (in balanced order), once with 1% incline and once with 0% incline, to investigate the effect of the gradient on V̇O2.&#x0D; Results&#x0D; The results revealed a significant increase in the cardiorespiratory response on the treadmill compared with the track for V̇O2 (+12.6 ± 5.5%, p &lt; 0.001, Dz = 2.6), heart rate (+5.5 ± 3.7%, p &lt; 0.001, Dz = 1.5), and minute ventilation (+15.0 ± 0.1%, p &lt; 0.001, Dz = 2.6). Data from the additional four participants showed that a 1% gradient increased V̇O2 by 4.4 ± 2.4% (p = 0.026) compared with a 0% gradient.&#x0D; Discussion/Conclusion&#x0D; This study shows that running on this particular treadmill model induces significantly higher cardiorespiratory responses compared with outdoor running, and that setting the incline to 1% significantly adds to this difference, instead of dampening it. These findings challenge the widely held assumption that treadmills should be set at 1% incline to yield equivalent cardiorespiratory responses to overground running. Each laboratory should test their unique settings to ascertain whether corrections based on incline are necessary.

Optimizing wearable motion tracking by assessing sagittal joint angle accuracy with minimal sensor use

Introduction&#x0D; Wearable motion tracking technology often focuses on reducing the number of sensors to simplify design and lower costs. Research has shown that single IMUs can reconstruct leg kinematics (Gholami et al., 2020; Hossain et al., 2022; Lim et al., 2020) and ground reaction forces (Jiang et al., 2020) effectively. Additionally, model-based methods have demonstrated the feasibility of using fewer gyroscopes to estimate stride length and motion range in healthy individuals and patients with coxarthritis (Salarian et al., 2013). In this study, we aim to assess the precision of sagittal joint angle estimations using strain sensors while minimizing sensor count.&#x0D; Methods&#x0D; We conducted a study with ten participants based on our previous work that involved collecting single-leg treadmill running data to monitor lower limb joint angles with piezoresistive strain sensors. Subjects ran on an instrumented treadmill at 8-10 km/h, wearing athletic pants embedded with nine strain sensors located on the hip, knee, and ankle. Optical motion capture provided reference kinematics. Our prior research achieved less than 1.5° error in the sagittal plane using a machine-learning approach. The current study explores the extent to which sensor reduction is possible without meaningful loss of accuracy. Three evaluation measures were used for assessment: Pearson correlation, dynamic time warping, and root-mean-squared error.&#x0D; Results&#x0D; The results from our correlation analysis will be used to develop a model that optimally balances between accuracy and minimizing the number of sensors. This has practical implications in sports science, where athletes could benefit from less intrusive and more comfortable performance monitoring, and in healthcare, for remote monitoring of patients with mobility issues.&#x0D; References&#x0D; Gholami, M., Napier, C., &amp; Menon, C. (2020). Estimating lower extremity running gait kinematics with a single accelerometer: A deep learning approach. Sensors, 20(10), Article 2939. https://doi.org/10.3390/s20102939&#x0D; Hossain, M. S., Bin, Dranetz, J., Choi, H., &amp; Guo, Z. (2022). DeepBBWAE-Net: A CNN-RNN based deep superlearner for estimating lower extremity sagittal plane joint kinematics using shoe-mounted IMU sensors in daily living. IEEE Journal of Biomedical and Health Informatics, 26(8), 3906-3917. https://doi.org/10.1109/jbhi.2022.3165383&#x0D; Jiang, X., Napier, C., Hannigan, B., Eng, J. J., &amp; Menon, C. (2020). Estimating vertical ground reaction force during walking using a single inertial sensor. Sensors, 20(15), Article 4345. https://doi.org/10.3390/s20154345&#x0D; Lim, H., Kim, B., &amp; Park, S. (2020). Prediction of lower limb kinetics and kinematics during walking by a single IMU on the lower back using machine learning. Sensors, 20(1), Article 130. https://doi.org/10.3390/s20010130&#x0D; Salarian, A., Burkhard, P. R., Vingerhoets, F. J. G., Jolles, B. M., &amp; Aminian, K. (2013). A novel approach to reducing number of sensing units for wearable gait analysis systems. IEEE Transactions on Biomedical Engineering, 60(1), 72–77. https://doi.org/10.1109/TBME.2012.2223465

Time to stability of treadmill running kinematics in novel footwear with different midsole thickness

Running studies, particularly those examining footwear effects, commonly use warm-up or familiarization periods prior to testing. There is no consensus for how long these familiarization periods should be to ensure stable running kinematics prior to experimental testing in novel footwear. The aim of this study was to assess the time to stability of kinematic variables during treadmill running in novel compared to habitual neutral cushion footwear in distance runners. A cross-sectional analysis of 15 distance runners (seven women, eight men) during 10-minute treadmill running bouts in minimal, neutral cushion, and maximal cushioned footwear was conducted while lower extremity kinematics were recorded for 10 s at the end of each minute. Test-retest intra-class correlation coefficients (ICC, 3, k) were used to detect time to stability in cadence, vertical oscillation, peak dorsiflexion angle, peak eversion angle, and peak knee flexion angle. All kinematic variables were stabilized within two to three minutes (ICC < 0.90) and the type of novel footwear did not influence time to stability. These findings indicate that a two to three minute, ∼310–540 steps, depending on running cadence, familiarization period, regardless of footwear novelty, is sufficient for stabilization of these kinematic variables during treadmill running.

Effects of Different Wearable Resistance Placements on Running Stability.

Stability during running has been recognized as a crucial factor contributing to running performance. This study aimed to investigate the effects of wearable equipment containing external loads on different body parts on running stability. Fifteen recreational male runners (20.27 ± 1.23 years, age range 19-22 years) participated in five treadmill running conditions, including running without loads and running with loads equivalent to 10% of individual body weight placed on four different body positions: forearms, lower legs, trunk, and a combination of all three (forearms, lower legs, and trunk). A tri-axial accelerometer-based smartphone sensor was attached to the participants' lumbar spine (L5) to record body accelerations. The largest Lyapunov exponent (LyE) was applied to individual acceleration data as a measure of local dynamic stability, where higher LyE values suggest lower stability. The effects of load distribution appear in the mediolateral (ML) direction. Specifically, running with loads on the lower legs resulted in a lower LyE_ML value compared to running without loads (p = 0.001) and running with loads on the forearms (p < 0.001), trunk (p = 0.001), and combined segments (p = 0.005). These findings suggest that running with loads on the lower legs enhances side-to-side local dynamic stability, providing valuable insights for training.

The Relationship between the Change in Pelvic Alignment during Moderate-Intensity Running and the Subjective Rating of Perceived Exertion, Rating of Perceived Exertion for Legs and Gluteus Muscles Fatigue in Female Novice and Recreational Runners

Running has become 1 of the 2 most well-known exercises for health; however, running may cause injuries. The purpose of this analytical descriptive study was to examine the occurrence of pelvic drop during moderate-intensity running in female novice and recreational runners; as well as investigating the relationship between the change in pelvic alignment and Rating of Perceived Exertion (RPE), Rating of Perceived Exertion for Legs (RPElegs) and Gluteus muscles fatigue in novice and recreational runners. The participants, aged between 18 and 35 years old, comprised 27 novice runners (less than 1 year of running experience) and 27 recreational runners (2 - 4 years running experience). The participants in both groups performed the maximal oxygen uptake (VO2max) test and ran at a self-selected speed on a treadmill for 30 min at moderate-intensity within the specified heart rate range of 40 - 59 % heart rate reserve (HRR). RPE, RPElegs and sEMG were collected every 2 min and the pelvic kinematic data were also recorded every minute during the 30 min treadmill running test. The data were analyzed with a statistical significance level at p-value &lt; 0.05. The results demonstrated that the time in starting pelvic drop was 8.15 ± 5.07 and 18.37 ± 6.70 min in female novice and recreational runner groups, respectively (p &lt; 0.01). Pearson’s correlations showed relationship between the pelvic alignment and RPE in novice runners (r = 0.47, p &lt; 0.01) and recreational runners (r = 0.39, p &lt; 0.01). Besides, Pearson’s correlations showed relationship between the pelvic alignment and RPElegs in novice runners (r = 0.48, p &lt; 0.01) and recreational runners (r = 0.32, p &lt; 0.01). In both groups, there was no relationship between the pelvic alignment and Gluteus medius and Gluteus maximus muscle fatigue. According to the study, the occurrence of a pelvic drop in novice runners was faster than recreational runners. The study indicated that consideration of RPE and RPElegs variables might be beneficial for female runners and future studies. HIGHLIGHTS The occurrence of pelvic drop in novice runners was faster than recreational runners. There was a relationship between the change in pelvic alignment and RPE and also RPElegs in female novice and recreational runners. The study indicated that consideration of RPE and RPElegs variables might be beneficial for female runners and future studies. GRAPHICAL ABSTRACT

Analgesic Effect of Exercise on Neuropathic Pain via Regulating the Complement Component 3 of Reactive Astrocytes.

Exercise has been proven to be an efficient intervention in attenuating neuropathic pain. However, the underlying mechanisms that drive exercise analgesia remain unknown. In this study, we aimed to examine the role of complement component 3 (C3) in neuropathic pain and whether antinociceptive effects are produced by exercise via regulating C3 in mice. In this study, using a spared nerve injury (SNI)-induced neuropathic pain mice model, C57BL/6J mice were divided into 3 groups: Sham mice, SNI mice, and SNI + Exercise (Ex) mice with 30-minute low-intensity aerobic treadmill running (10 m/min, no inclination). Paw withdrawal threshold; thermal withdrawal latency; and glial fibrillary acidic protein, C3, tumor necrosis factor-α, and interlukin-1β expression in the spinal cord were monitored. C3 knockout (KO) mice were further used to verify the role of C3 in neuropathic pain. von Frey test, acetone test, and CatWalk gait analysis revealed that treadmill exercise for 4 weeks reversed pain behaviors. In addition, exercise reduced astrocyte reactivity (SNI mean = 14.5, 95% confidence interval [CI], 12.7-16.3; SNI + Ex mean = 10.3, 95% CI, 8.77-11.9, P = .0003 SNI + Ex versus SNI) and inflammatory responses in the spinal cord after SNI. Moreover, it suppressed the SNI-induced upregulation of C3 expression in the spinal cord (SNI mean = 5.46, 95% CI, 3.39-7.53; SNI + Ex mean = 2.41, 95% CI, 1.42-3.41, P = .0054 SNI + Ex versus SNI in Western blot). C3 deficiency reduced SNI-induced pain and spinal astrocyte reactivity (wild type mean = 7.96, 95% CI, 6.80-9.13; C3 KO mean = 5.98, 95% CI, 5.14-6.82, P = .0052 C3 KO versus wild type). Intrathecal injection of recombinant C3 (rC3) was sufficient to produce mechanical (rC3-Ex mean = 0.77, 95% CI, 0.15-1.39; rC3 mean = 0.18, 95% CI, -0.04 to 0.41, P = .0168 rC3-Ex versus rC3) and cold (rC3-Ex mean = 1.08, 95% CI, 0.40-1.77; rC3 mean = 3.46, 95% CI, 1.45-5.47, P = .0025 rC3-Ex versus rC3) allodynia in mice. Importantly, exercise training relieved C3-induced mechanical and cold allodynia, and the analgesic effect of exercise was attenuated by a subeffective dose of intrathecal injection of C3. Overall, these results suggest that exercise suppresses neuropathic pain by regulating astroglial C3 expression and function, thereby providing a rationale for the analgesic effect of exercise as an acceptable alternative approach for treating neuropathic pain.

Myocardial proteome changes in aortic stenosis rats subjected to long-term aerobic exercise.

The effects of exercise training (ET) on the heart of aortic stenosis (AS) rats are controversial and the mechanisms involved in alterations induced by ET have been poorly clarified. In this study, we analyzed the myocardial proteome to identify proteins modulated by moderate-intensity aerobic ET in rats with chronic supravalvular AS. Wistar rats were divided into four groups: sedentary control (C-Sed), exercised control (C-Ex), sedentary aortic stenosis (AS-Sed), and exercised AS (AS-Ex). ET consisted of five treadmill running sessions per week for 16 weeks. Statistical analysis was performed by ANOVA or Kruskal-Wallis and Goodman tests. Results were discussed at a significance level of 5%. At the end of the experiment, AS-Ex rats had higher functional capacity, lower blood lactate concentration, and better cardiac structural and left ventricular (LV) functional parameters than the AS-Sed. Myocardial proteome analysis showed that AS-Sed had higher relative protein abundance related to the glycolytic pathway, oxidative stress, and inflammation, and lower relative protein abundance related to beta-oxidation than C-Sed. AS-Ex had higher abundance of one protein related to mitochondrial biogenesis and lower relative protein abundance associated with oxidative stress and inflammation than AS-Sed. Proteomic data were validated for proteins related to lipid and glycolytic metabolism. Chronic pressure overload changes the abundance of myocardial proteins that are mainly involved in lipid and glycolytic energy metabolism in rats. Moderate-intensity aerobic training attenuates changes in proteins related to oxidative stress and inflammation and increases the COX4I1 protein, related to mitochondrial biogenesis. Protein changes are combined with improved functional capacity, cardiac remodeling, and LV function in AS rats.

Treadmill Running Regulates Adult Neurogenesis, Spatial and Non-spatial Learning, Parvalbumin Neuron Activity by ErbB4 Signaling.

Exercise can promote adult neurogenesis and improve symptoms associated with schizophrenia and other mental disorders via parvalbumin(PV)-positive GABAergic interneurons in the dentate gyrus ErbB4 is the receptor of neurotrophic factor neuregulin 1, expressed mostly in PV-positive interneurons. Whether ErbB4 in PV-positive neurons mediates the beneficial effect of exercise and adult neurogenesis on mental disorder needs to be further investigation. Here, we first conducted a four-week study on the effects of AG1478, an ErbB4 inhibitor, on memory and neurogenesis. AG1478 significantly impaired the performance in several memory tasks, including the T-maze, Morris water maze, and contextual fear conditioning, downregulated the expression of total ErbB4 (T-ErbB4) and the ratio of phosphate-ErbB4 (p-ErbB4) to T-ErbB4, and associated with neurogenesis impairment. Interestingly, AG1478 also appeared to decrease intracellular calcium levels in PV neurons, which could be reversed by exercise. These results suggest exercise may regulate adult neurogenesis and PV neuron activity through ErbB4 signaling. Overall, these findings provide further evidence of the importance of exercise for neurogenesis and suggest that targeting ErbB4 may be a promising strategy for improving memory and other cognitive functions in individuals with mental disorders.

The impact of general and/or specific warm-up on power and velocity during squat and bench-press training

The study aimed to compare the effects of two warm-up strategies on mechanical force production during bench press and squat resistance training sessions. Twenty-six trained male subjects (24.37±5.83years, 75.48±12.12kg, 1.74±0.07m) performed a squat or bench press resistance training session after a specific warm-up (SWU) or general warm-up followed by a specific warm-up (GSWU). The SWU included 2x6 repetitions at 32% and 64% of the maximal load (1RM), respectively. The GSWU included 10 minutes of treadmill running (70% of heart rate reserve) followed by SWU. The resistance training session consisted of 3x6 with a load of 80% 1RM. Mechanical (mean propulsive velocity, mean propulsive power and velocity loss), physiological [heart rate (HR), blood lactate concentration], and psychophysiological variables (rating of perceived exertion) were evaluated. In the bench press and squat resistance training sessions, no differences were found in the mechanical and psychophysiological variables. When performing the bench press, the GSWU caused an increased HR response after warm-up (100.00±16.93bpm vs. 110.57±9.69bpm, p=0.03; ES=0.65, moderate effect). GSWU or SWU can both be used as preparatory activities for bench press and squat resistance training performance without related restrictions. These findings may be helpful for professionals to provide appropriate warm-up strategies to maximize resistance training. Keywords: Pre-exercise, Strength, T-Force, Velocity, Physiology, Resistance Training

The mechanical response to hockey-specific running gait: implications for the objective monitoring of (p)rehabilitation

ABSTRACT Field hockey is characterized by a unique dribbling position which has been associated with a prevalence of low back pain and lumbar injury. To quantify the biomechanical response of the hockey-specific running gait, twelve field hockey players completed treadmill running at speeds of 6, 9 and 12 km·hr−1 with a normal running gait and whilst manipulating the hockey stick to replicate dribbling. Mechanical loading was quantified using tri-axial accelerometery at L4, and muscular activity was measured for biceps femoris (BF), gluteus medius (GM) and quadratus lumborum (QL) of each limb. Running with the stick elicited greater mechanical loading in the medio-lateral (p = 0.001) and antero-posterior (p = 0.003) planes, and increased peak (p = 0.004) and mean (p = 0.002) EMG response of QL (p = 0.004). The greater planar mechanical loading and QL activation in response to hockey-specific running technique support epidemiological observations of lower back pain prevalence. The sensitivity of uni-axial mechanical loading to the hockey-specific running posture provides an efficacious means of objectively monitoring mechanical loading in-vivo, whilst the QL activation response has implications for (p)rehabilitative interventions. Running posture and speed can be considered as discrete progressions when considering training load.