Impact of Taekwondo training on cognitive and physical function in elderly individuals: A comprehensive review of randomized controlled trials.

BACKGROUND: Researchers have investigated the physical and psychosocial advantages of Taekwondo for older adults. However, prior studies of Taekwondo's impact on physical function and psychological well-being in this demographic have produced inconsistent findings. Thus, this systematic review aimed to assess how Taekwondo practice affects the physical function and psychological well-being of older adults. METHODS: We systematically searched PubMed, EMBASE, CINAHL, SPORTDiscus, Scopus, Korea Education and Research Information Service, Korean Studies Information Service System, Korean National Assembly Library, Research Information Sharing Service, National Digital Science Library, and China National Knowledge Infrastructure from their inception to December 2023. Two reviewers independently selected and extracted data from each study. We calculated effect sizes using a random-effects model with a 95 % confidence interval (CI) and evaluated study quality using the Physiotherapy Evidence Database scale. RESULTS: This review included ten studies with 227 participants aged 66.1-73.6 years. The meta-analysis revealed significant enhancements in cognitive function [Korean Version of Mini-Mental State Examination, standard mean difference (SMD) = 0.700, 95 % CI (0.364-1.037), I2 = 0 %, p < .001], blood indicators [ß-amyloid, SMD = 0.613, 95 % CI (0.103-1.123), I2 = 34.920 %, p < .05; brain-derived neurotrophic factor, SMD = 0.566, 95 % CI (0.166-0.966), I2 = 0 %, p < .01; high-density lipoprotein cholesterol, SMD = 0.677, 95 % CI (0.357-0.966), I2 = 0 %, p < .001; low-density lipoprotein cholesterol, SMD = 0.809, 95 % CI (0.376-1.242), I2 = 42.621 %, p < .001; and total cholesterol, SMD = 0.979, 95 % CI (0.603-1.356), I2 = 22.221 %, p < .001], and physical function [lean body mass, SMD = 0.465, 95 % CI (0.109-0.821), I2 = 0 %, p < .05, and handgrip strength, SMD = 0.929, 95 % CI (0.194-1.663), I2 = 48.217 %, p < .05]. CONCLUSIONS: This meta-analysis indicates that Taekwondo training is a beneficial therapy with protective effects on cognitive function, physical function, and body composition in older adults. These findings highlight its potential significance in cognitive rehabilitation and physiological health promotion among this demographic population.

Automatic Clinical Assessment of Swallowing Behavior and Diagnosis of Silent Aspiration Using Wireless Multimodal Wearable Electronics.

Dysphagia is more common in conditions such as stroke, Parkinson's disease, and head and neck cancer. This can lead to pneumonia, choking, malnutrition, and dehydration. Currently, the diagnostic gold standard uses radiologic imaging, the videofluoroscopic swallow study (VFSS); however, it is expensive and necessitates specialized facilities and trained personnel. Although several devices attempt to address the limitations, none offer the clinical-grade quality and accuracy of the VFSS. Here, this study reports a wireless multimodal wearable system with machine learning for automatic, accurate clinical assessment of swallowing behavior and diagnosis of silent aspirations from dysphagia patients. The device includes a kirigami-structured electrode that suppresses changes in skin contact impedance caused by movements and a microphone with a gel layer that effectively blocks external noise for measuring high-quality electromyograms and swallowing sounds. The deep learning algorithm offers the classification of swallowing patterns while diagnosing silent aspirations, with an accuracy of 89.47%. The demonstration with post-stroke patients captures the system's significance in measuring multiple physiological signals in real-time for detecting swallowing disorders, validated by comparing them with the VFSS. The multimodal electronics can ensure a promising future for dysphagia healthcare and rehabilitation therapy, providing an accurate, non-invasive alternative for monitoring swallowing and aspiration events.

Comparison of face mask effects on cardiorespiratory responses between physically active and sedentary individuals.

BACKGROUND: Alterations caused by face masks on physiological responses vary among different population groups. This study aimed to investigate whether physically active and sedentary individuals respond differently to face mask use during exercise. METHODS: Sixteen healthy college students were divided into two groups: Physically active group (N.=10; 26.50±2.80 years) and Sedentary group (N.=6; 26.33±2.81 years). They performed three maximal cardiopulmonary exercise test (CPET)s following the Bruce protocol: one without a face mask (NON), one with a surgical mask (SUR) and one with a cloth mask (CLO). Cardiorespiratory parameters and heart rate were monitored continuously during the test. Blood pressure, oxygen saturation and lactate level were measured immediately before and after exertion. RESULTS: Significant differences were found between the Physically active and the Sedentary group in peak VO2 (VO2peak) in NON (P=0.030). However, this difference disappeared when the face masks were used. Furthermore, VO2/kg (P=0.002) and METs (P=0.002) decreased significantly at the respiratory compensation point (RCP) only in the Physically active group with face masks. No significant differences were found between the two groups for exercise time, lactate level and dyspnea (P>0.05). CONCLUSIONS: The decrease in exercise tolerance and cardiorespiratory responses, particularly VO2peak, due to face mask use was greater in physically active individuals compared to sedentary individuals. Population group characteristics should be considered when adapting face masks to daily life.

Neural network model for prediction of possible sarcopenic obesity using Korean national fitness award data (2010-2023).

Sarcopenic obesity (SO) is characterized by concomitant sarcopenia and obesity and presents a high risk of disability, morbidity, and mortality among older adults. However, predictions based on sequential neural network SO studies and the relationship between physical fitness factors and SO are lacking. This study aimed to develop a predictive model for SO in older adults by focusing on physical fitness factors. A comprehensive dataset of older Korean adults participating in national fitness programs was analyzed using sequential neural networks. Appendicular skeletal muscle/body weight was defined as SO using an anthropometric equation. Independent variables included body fat (BF, %), waist circumference, systolic and diastolic blood pressure, and various physical fitness factors. The dependent variable was a binary outcome (possible SO vs normal). We analyzed hyperparameter tuning and stratified K-fold validation to optimize a predictive model. The prevalence of SO was significantly higher in women (13.81%) than in men, highlighting sex-specific differences. The optimized neural network model and Shapley Additive Explanations analysis demonstrated a high validation accuracy of 93.1%, with BF% and absolute grip strength emerging as the most influential predictors of SO. This study presents a highly accurate predictive model for SO in older adults, emphasizing the critical roles of BF% and absolute grip strength. We identified BF, absolute grip strength, and sit-and-reach as key SO predictors. Our findings underscore the sex-specific nature of SO and the importance of physical fitness factors in its prediction.

Effects of Exercise on Urinary AD7c-NTP (Alzheimer-Associated Neuronal Thread Protein) Levels and Cognitive Function Among Active Korean Elderly: A Randomized Controlled Trial.

Background: Alzheimer-associated neuronal thread protein (AD7c-NTP) has been demonstrated to have high diagnostic accuracy in differentiating Alzheimer's disease (AD) patients from healthy individuals. However, it is yet unclear whether exercise can lower the level of AD7c-NTP in urine among active Korean elderly. Objective: To assess the effect of exercise on AD7c-ntp levels in urine and cognitive function among active Korean elderly. Methods: In total, 40 Korean elderly (≥65 years) were divided into Active Control group (CG, n = 10), Aerobic exercise group (AG, n = 18), and combined Resistance/Aerobic exercise group (RAG, n = 12). A total of 12 weeks of exercise intervention was implemented. At week 0 and 12, cognitive performance (Korean Mini-Mental State Examination, Korean-Color Word Stroop test), grip strength, and body composition (muscle mass and body fat percentage) were measured. Also, a morning urine sample was obtained from each subject. The level of AD7c-NTP was measured using competitive enzyme-linked immunosorbent assay (ELISA). Results: After 12 weeks of exercise intervention, there was a significant difference of AD7c-NTP levels between RAG and CG (p = 0.026), AG and CG (p = 0.032), respectively. Furthermore, the AD7c-NTP levels in urine showed negative correlation with K-MMSE scores (r = -0.390, p = 0.013) and grip strength (r = -0.376, p = 0.017), among all participants after exercise intervention. Conclusions: This is the first study to investigate urine biomarker through exercise intervention. In future stuides, participants who have low cognitive function and low activity levels need to be recruited to observe more significant 'Exercise' effect.

Respiratory Parameters as Predictors of Balance and Gait Ability in Patients with Stroke at Discharge.

Pulmonary complications are frequent in stroke, contributing to both mortality and morbidity rates. Respiratory parameters in such patients encompass both pulmonary function and respiratory muscle strength. Identifying respiratory function variables that influence the balance and gait ability of patients with stroke is crucial for enhancing their recovery in these aspects. However, no study has assessed predictions for a comprehensive array of balance and gait abilities in such patients. We aimed to examine whether initial respiratory muscle strength and pulmonary function can predict balance and gait ability at discharge from a rehabilitation program. Thirty-one patients with stroke were included in this prospective observational study. Multiple regression models with a forward selection procedure were employed to identify respiratory parameters (including peak expiratory flow and maximal expiratory pressure) that contributed to the results of balance assessments and gait evaluations at the time of discharge. The peak expiratory flow (PEF) served as a predictor explaining 42.0% of the variance. Similarly, the maximal expiratory pressure (MEP) was a predictor variable explaining 32.0% of the variance. PEF and MEP assessments at the initial stage as predictive factors for both balance and gait ability are important in stroke management.

Differences in the Clinical and Molecular Profiles of Subungual Melanoma and Acral Melanoma in Asian Patients.

Subungual melanoma (SUM) is a rare type of malignant melanoma that arises beneath the nails. SUM is categorized as a type of acral melanoma (AM), which occurs on the hands and feet. SUM is an aggressive type of cutaneous melanoma that is most common among Asian patients. Recent studies reveal that SUM and AM might have different molecular characteristics. Treatment of melanoma relies on analysis of both clinical and molecular data. Therefore, the clinical and molecular characteristics of SUM need to be established, especially during metastasis. To define the mutation profiles of SUM and compare them with those of AM, we performed next-generation sequencing of primary and metastatic tumors of SUM and AM patients. Subungual location was a better independent prognostic factor than acral location for better overall survival (p = 0.001). Patients with SUM most commonly had the triple wild-type (75%) driven by GNAQ (58%) and KIT (25%) mutations, whereas patients with AM had BRAF (28.6%) and RAF (14.3%) molecular types of mutations. Single-nucleotide variations (SNVs) were more common in SUM than in AM, whereas copy number alterations (CNAs) were more common metastatic lesions of AM. Metastatic tumors in patients with SUM and AM showed increases in CNAs (43% and 80%, respectively), but not in SNVs. The number of CNAs increased during metastasis. When compared with AM, SUM has distinct clinical and molecular characteristics.

Synthesis and Characterization of a Multi-Walled Carbon Nanotube-Ionic Liquid/Polyaniline Adsorbent for a Solvent-Free In-Needle Microextraction Method.

Sample preparation is an essential process when handling complex matrices. Extraction without using a solvent requires the direct transfer of analytes from the sample to the adsorbent either in the gas or liquid phase. In this study, a wire coated with a new adsorbent was fabricated for in-needle microextraction (INME) as a solvent-free sample extraction method. The wire inserted into the needle was placed in the headspace (HS), which was saturated with volatile organic compounds from the sample in a vial. A new adsorbent was synthesized via electrochemical polymerization by mixing aniline with multi-walled carbon nanotubes (MWCNTs) in the presence of an ionic liquid (IL). The newly synthesized adsorbent using IL is expected to achieve high thermal stability, good solvation properties, and high extraction efficiency. The characteristics of the electrochemically synthesized surfaces coated with MWCNT-IL/polyaniline (PANI) adsorbents were characterized using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and atomic force microscopy (AFM). Then, the proposed HS-INME-MWCNT-IL/PANI method was optimized and validated. Accuracy and precision were evaluated by analyzing replicates of a real sample containing phthalates, showing spike recovery between 61.13% and 108.21% and relative standard deviations lower than 15%. The limit of detection and limit of quantification of the proposed method were computed using the IUPAC definition as 15.84~50.56 µg and 52.79~168.5 µg, respectively. We concluded that HS-INME using a wire coated with the MWCNT-IL/PANI adsorbent could be repeatedly used up to 150 times without degrading its extraction performance in an aqueous solution; it constitutes an eco-friendly and cost-effective extraction method.

Cardiopulmonary Exercise Test With Comorbidity Index Before Allogeneic Hematopoietic Stem Cell Transplantation.

PURPOSE: To evaluate the role of the cardiopulmonary exercise test (CPET) with comorbidity index as a predictor of overall survival (OS) and non-relapse mortality (NRM) in patients with hematological malignancies who undergo allogeneic hematopoietic stem cell transplantation (HSCT). METHODS: We retrospectively analyzed consecutive adult patients with hematological malignancies who underwent HLA-matched donor-HSCT at Chungnam National University Hospital (Daejeon, South Korea) between January 2014 and December 2020. Maximal oxygen consumption (VO2max) was classified using the recommendations of the Mayo Clinic database. RESULTS: Of 72 patients, 38 (52.8%) had VO2max values lower than the 25th percentile (VO2max ≤ 25th) of an age- and sex-matched normal population. Patients with VO2max ≤ 25th had no significant differences both OS and NRM (30 month OS 29.8% vs 41%, P = .328; and 30 month NRM 16% vs 3.3%, P = .222), compared with other patients. VO2max ≤ 25th was assigned a weight of 1 when added to the Hematopoietic Cell Transplantation-specific Comorbidity Index (HCT-CI) to form a composite comorbidity/CPET index (HCT-CI/CPET). Patients with HCT-CI/CPET scores of 0 to 1 demonstrated significantly better OS and NRM than did patients with HCT-CI/CPET scores ≥2 [median OS not reached vs 6 months, P < .001 and 30 month NRM 7.4% vs 33.3%, P = .006]. An HCT-CI/CPET score ≥2 was the only adverse risk factor for NRM on multivariate analysis [hazard ratio (HR) of NRM 10.36 (95% CI 1.486-2.25, P = .018)]. CONCLUSION: The composite HCT-CI/CPET score can predict the survival and mortality of patients with hematological malignancies who undergo allogeneic HSCT.

Enhancement of the solubility of recombinant proteins by fusion with a short-disordered peptide.

In protein biotechnology, large soluble fusion partners are widely utilized for increased yield and solubility of recombinant proteins. However, the production of additional large fusion partners poses an additional burden to the host, leading to a decreased protein yield. In this study, we identified two highly disordered short peptides that were able to increase the solubility of an artificially engineered aggregation-prone protein, GFP-GFIL4, from 0.6% to 61% (D3-DP00592) and 46% (D4-DP01038) selected from DisProt database. For further confirmation, the peptides were applied to two insoluble E. coli proteins (YagA and YdiU). The peptides also enhanced solubility from 52% to 90% (YagA) and from 27% to 93% (YdiU). Their ability to solubilize recombinant proteins was comparable with strong solubilizing tags, maltose-binding protein (40 kDa) and TrxA (12 kDa), but much smaller (< 7 kDa) in size. For practical application, the two peptides were fused with a restriction enzyme, I-SceI, and they increased I-SceI solubility from 24% up to 75%. The highly disordered peptides did not affect the activity of I-SceI while I-SceI fused with MBP or TrxA displayed no restriction activity. Despite the small size, the highly disordered peptides were able to solubilize recombinant proteins as efficiently as conventional fusion tags and did not interfere with the function of recombinant proteins. Consequently, the identified two highly disordered peptides would have practical utility in protein biotechnology and industry.

Relation of exercise capacity to comprehensive physical functions in individuals with ischemic stroke.

BACKGROUND: Impaired motor control, balance, muscle strength, and respiratory function may affect the exercise capacity related to motor performance and activities in individuals with stroke. OBJECTIVE: To identify a physical parameter that the exercise capacity has the most significant relationship among physical parameters related to motor function, trunk control, balance, and motor performance and activities in individuals with ischemic stroke. METHODS: In total, 241 ischemic stroke patients were recruited in this retrospective study. The clinical measurements included the 6-minute walk test (6 MWT), Montreal cognitive assessment (MoCA), Fugl-Meyer assessment-lower extremity motor function (FMA-LE), trunk impairment scale (TIS), Berg balance scale (BBS), timed up and go test (TUG), 10-meter walk test (10 MWT), functional ambulation category (FAC), and functional independence measure (FIM). RESULTS: The 6 MWT was significantly correlated with the FMA-LE, BBS, TUG, 10 MWT, FAC, and FIM, indicating negative or positive moderate correlations. Additionally, the FMA-LE, TIS, BBS, TUG, 10 MWT, FAC, and FIM, excluding the 6 MWT, showed moderate to strong correlations with all of the other outcome measures, whereas the MoCA showed significant correlations only with the BBS and FIM. CONCLUSIONS: In this study, the exercise capacity has the most significant relationship with the TUG parameter in stroke patients. Additionally, we suggest that significant relationships between 6 MWT and other comprehensive physical functions measurements are closely related to walking ability in individuals with stroke.

A new swallowing supplement for dysphagia in patients with Parkinson's disease.

Dysphagia associated with Parkinson's disease (PD) affects the mortality and quality of life of patients with PD. Avoiding aspiration and maintaining swallowing ability are among the concerns regarding PD care. Therefore, we developed a swallowing supplement for easier swallowing and tolerability in patients with PD. Thirty patients with PD and 50 healthy controls were enrolled and their swallowing function measured using the videofluoroscopic swallowing study (VFSS) and several dysphagia scales. The Unified Parkinson's Disease Rating Scale motor scores, Hoehn and Yahr stage, and levodopa doses were evaluated in patients with PD. The VFSS and survey were used to assess the viscosity, color, taste, nutrition, safety, and tolerability of the swallowing supplement. The MMSE score, serum albumin, and hemoglobin levels, and oral conditions were worse in the PD group than in the control group. Compared with controls, patients with PD had significantly lower total and sub-item scores of the swallowing quality of life (swal-QoL). Using commercialized yogurt, the pharyngeal delay time (PDT) and the modified penetration aspiration scale were higher in the PD group than in the control group. The swallowing supplement significantly shortened the PDT and pharyngeal transit time (PTT). Moreover, compared with commercialized yogurt, it improved pharyngeal wall coating, PTT, and aspiration in the videofluoroscopic dysphagia subscales. The survey scores were above average to good in the "easy swallowing" and "pharyngeal residual sense" items and tolerable in the remaining 6 preference items. This swallowing supplement could prevent aspiration and dysphagia complications in patients with PD.

Ultrasonographic Evaluation of Breast Cancer-related Lymphedema.

Lymphedema is one of the most common complications after breast cancer surgery. There are many diagnostic tools for lymphedema, but no standard method yet exists. Progressive Resistance Exercise (PRE) is expected to improve lymphedema without additional swelling. This study showed the therapeutic effects of PRE on lymphedema by using ultrasonography to measure the change in thickness of the muscle and subcutaneous tissue. The thickness of subcutaneous tissue decreased more in the PRE group than in the non-PRE group. Ultrasonography is widely used in many clinics because of its easy accessibility, safety, and inexpensiveness. Ultrasound is one of the best tools for diagnosing and determining treatment efficacy on breast cancer-related lymphedema (BCRL).

The Effect of Different Foot Orthosis Inverted Angles on Plantar Pressure in Children with Flexible Flatfeet.

Although orthotic modification using the inverted technique is available for the treatment of flatfoot, empirical evidence for the biomechanical effects of inverted-angle foot orthoses (FOs) is lacking. The aim of this study was to evaluate the effects of different FO inversion angles on plantar pressure during gait in children with flatfoot. Twenty-one children with flexible flatfeet (mean age 9.9 years) were enrolled in this study. The plantar pressures were measured for the rearfoot; medial and lateral midfoot; and medial, central, and lateral forefoot as participants walked on a treadmill while wearing shoes only and shoes with the following 3 orthotic conditions: (i) orthosis with no inverted angle, (ii) orthosis with a 15° inverted angle, and (iii) orthosis with a 30° inverted angle. A one-way repeated measures analysis of variance (ANOVA) with the Bonferroni-adjusted post-hoc test was used to compare the mean values of each orthotic condition. Compared with the shoe only condition, the peak pressure decreased significantly under the medial forefoot and rearfoot with all FOs (p <0.05). However, no significant differences in the peak pressure under the medial forefoot and rearfoot were observed between the FOs. The peak pressure under the medial midfoot increased significantly with all FOs, and a maximal increase in the peak pressure was obtained with a 30° inverted angle orthosis. Furthermore, the contact area under the medial midfoot and rearfoot increased significantly with all FOs, compared with the shoe only condition (p <0.05). Again, no significant differences were observed between the FOs. For plantar pressure redistribution, a FO with a low inverted angle could be effective, accommodative, and convenient for children with flatfoot.

Improving the accuracy of vehicle emissions profiles for urban transportation greenhouse gas and air pollution inventories.

Metropolitan greenhouse gas and air emissions inventories can better account for the variability in vehicle movement, fleet composition, and infrastructure that exists within and between regions, to develop more accurate information for environmental goals. With emerging access to high quality data, new methods are needed for informing transportation emissions assessment practitioners of the relevant vehicle and infrastructure characteristics that should be prioritized in modeling to improve the accuracy of inventories. The sensitivity of light and heavy-duty vehicle greenhouse gas (GHG) and conventional air pollutant (CAP) emissions to speed, weight, age, and roadway gradient are examined with second-by-second velocity profiles on freeway and arterial roads under free-flow and congestion scenarios. By creating upper and lower bounds for each factor, the potential variability which could exist in transportation emissions assessments is estimated. When comparing the effects of changes in these characteristics across U.S. cities against average characteristics of the U.S. fleet and infrastructure, significant variability in emissions is found to exist. GHGs from light-duty vehicles could vary by -2%-11% and CAP by -47%-228% when compared to the baseline. For heavy-duty vehicles, the variability is -21%-55% and -32%-174%, respectively. The results show that cities should more aggressively pursue the integration of emerging big data into regional transportation emissions modeling, and the integration of these data is likely to impact GHG and CAP inventories and how aggressively policies should be implemented to meet reductions. A web-tool is developed to aide cities in improving emissions uncertainty.

Effects of custom-made rigid foot orthosis on pes planus in children over 6 years old.

OBJECTIVE: To identify the effects of a custom-made rigid foot orthosis (RFO) in children over six years old with pes planus. METHODS: The medical records of 39 children (mean age, 10.3±4.09 years) diagnosed with pes planus, fitted with RFOs, and had who more than two consecutive radiological studies were reviewed. The resting calcaneal stance position (RCSP), anteroposterior talocalcaneal angle (APTCA), lateral talocalcaneal angle (LTTCA), the lateral talometatarsal angle (LTTMA), and calcaneal pitch (CP) of both feet were measured to evaluate foot alignment. After diagnosis, children were fitted with a pair of RFOs and recommended to walk with heel strike and reciprocal arm swing to normalize the gait pattern. A follow-up clinical evaluation with radiological measurements was performed after 12-18 months and after 24 months of RFO application. Post-hoc analysis was used to test for significant differences between the radiological indicators and RCSP. RESULTS: With RFOs, all radiological indicators changed in the corrective direction except LTTCA. RCSP and CP in the third measurement showed significant improvement in comparison with the second and baseline measurements. Additionally, APTCA and LTTMA revealed improvements at the third measurement versus the baseline measurements. CONCLUSION: This study revealed that radiological indicators improved significantly after 24 months of RFO application. A prospective long-term controlled study with radiographical evaluation is necessary to confirm the therapeutic effects of RFOs and to determine the optimal duration of wear in children with pes planus.

Recurrent cerebral infarction caused by mobile aortic arch thrombus refractory to warfarin therapy.

The mobile thrombus in the aortic arch is a rare condition, which becomes rarer when associated with cerebral infarction, resulting in disabling complications. Transesophageal echocardiography is useful for detecting the source of thrombi in the heart and aortic arch. Here, we report a case of a patient who suffered from recurrent cerebral infarction four times during the previous 18 months due to mobile thrombus in the aortic arch despite anticoagulant therapy. The thrombus with rocking motion (9.6 and 8 mm) was laid in the top of the aortic arch, and surgical resection was not allowed due to the location. We began anticoagulation therapy initially with heparin followed by a combination of warfarin, aspirin, and atorvastatin with an international normalized ratio between 2 and 3. The size of the aortic thrombi was significantly decreased by 3 mm and stabilized after 18 months.

Impact of traffic oscillations on freeway crash occurrences.

Traffic oscillations are typical features of congested traffic flow that are characterized by recurring decelerations followed by accelerations (stop-and-go driving). The negative environmental impacts of these oscillations are widely accepted, but their impact on traffic safety has been debated. This paper describes the impact of freeway traffic oscillations on traffic safety. This study employs a matched case-control design using high-resolution traffic and crash data from a freeway segment. Traffic conditions prior to each crash were taken as cases, while traffic conditions during the same periods on days without crashes were taken as controls. These were also matched by presence of congestion, geometry and weather. A total of 82 cases and about 80,000 candidate controls were extracted from more than three years of data from 2004 to 2007. Conditional logistic regression models were developed based on the case-control samples. To verify consistency in the results, 20 different sets of controls were randomly extracted from the candidate pool for varying control-case ratios. The results reveal that the standard deviation of speed (thus, oscillations) is a significant variable, with an average odds ratio of about 1.08. This implies that the likelihood of a (rear-end) crash increases by about 8% with an additional unit increase in the standard deviation of speed. The average traffic states prior to crashes were less significant than the speed variations in congestion.