Exercise Speed Research Articles

The effect of knee braces on knee joint kinematics at different exercise speeds

ABSTRACT This study aims to investigate the influence of a new semi-rigid knee joint braces on kinematics using the Opti-knee knee joint kinematic analysis system at various exercise speeds. Twenty-four healthy young male adults were recruited for this study. Participants were randomly assessed while wearing and not wearing knee brace at four different speeds on a treadmill: normal walking (3.6 km/h), brisk walking (5.4 km/h), jogging (9 km/h), and moderate intensity running (10.8 km/h). Six degrees of freedom kinematic data from the knee joint were collected. Paired t-tests were conducted to calculate the kinematic differences. At speeds of 3.6 km/h and 5.4 km/h, wearing the knee brace led to reduced knee joint mobility in anterior-posterior translation, superior-inferior translation, internal-external rotation, and flexion-extension angles during the stance phase (P < 0.05). At 9 km/h, wearing the brace reduced knee joint internal-external rotation and flexion-extension mobility during the stance phase (P < 0.05). At 10.8 km/h, wearing the brace reduced knee joint flexion-extension mobility during the stance phase (P < 0.05). Wearing brace has significant influence on knee kinematics at four speeds, and the effect of brace varies with the speed of movement.

A Construction of Physical Exercises Program at Home to Improve Physical and Mental Development for the Children with Mental Retardation

Background and Aim: The Fifth Plenary Session of the 18th CPC Central Committee issued the outline of the Healthy China 2030 plan, and the health problem of the disabled was put forward as one of the key problems to be solved. According to our world in data 2016, there were about 11 million men and 8 million women with children with mental retardation in our country. The incidence of children with mental retardation in our country ranks first among five major countries in the world. Studies had shown that the incidence of overweight and obesity in children with mental retardation was significantly higher than that of normal peers. Coupled with limited intellectual ability, sedentary lifestyle and lack of exercise, lack of social support related to physical exercise, and other factors, being overweight and obese had a great impact on the physical, psychological, and social functions of children with mental retardation, and this impact may continue into adulthood, posing a serious threat to physical and mental health. Therefore, how to promote physical exercises for children with mental retardation, to promote their physical and mental health has become one of the important topics paid attention to by the researchers. Materials and Methods: Some 31experts participated in this study, divided into three groups: the first group consisted of 7 experts who conducted expert interviews; the second group organized 19 experts who used the Delphi method to conduct argumentation; and the third group consisted of 7 experts who appreciated the method. Researched process :(1) Collecting literature; (2) Organizing expert interviews. The influencing factors and environment of family exercises for children were discussed, 191 movements were designed and screened, and the content system of movements for home physical exercises was initially constructed. (3) 19 experts were selected by purposeful sampling method, and three rounds of the questionnaire were used to verify the index system by Delphi method; (4) Verify physical exercises program through connoisseurship; (5) Develop and implement physical exercise programs at home to meet the different psychological needs. Result: (1) The content index system of family physical exercise for children with mental retardation was preliminarily established, including 191 action indicators；(2) after two rounds of validation of the expert's Delphi questionnaire, 2 level 2 indicators of the warm-up module and 11 level 3 indicators of physical exercise module were excluded. The mean value of the remaining indicators was &gt;3.5 and CV&lt;0.25, and other indicators were retained; (3) after the connoisseurship by seven experts, the indicator system was finalized, including 3 first-level indicators and 22 second-level indicators in the warm-up module. 5 level 1 indicators, 17 level 2 indicators, and 135 level 3 indicators for the physical exercise module. 3 level 1 indicators and 21 level 2 indicators for the relaxation and stretching module; (4) prepare 5 physical exercise programs with different psychological needs, and practice them. Conclusion: (1) Starting from the individual level, interpersonal level, and community level, this project highlighted the core status of the children, paid attention to the interaction form and environment maintenance at the community level, and promoted the development of children's sports desire and psychomotor needs. (2) The program cleverly combines professionalism and practicality, ensuring that children with different needs can find the right speed and type of exercise for them at home. Through this program, children with mental retardation cannot only enjoy tailored exercise programs but also receive ongoing motivation and support in interaction and innovation, making health and vitality a goal within reach of every family with exceptional children.

Home-based resistance training performed at either fast or slow speeds improves power output in older adults

PurposeWe investigated the effect of an unsupervised, body mass- home-based resistance training program in older adults performed at either a fast or slow contractile speed on changes to muscle-power, -volume, -architecture, and fatigue resistance of the knee extensors. MethodsThirty-two male older adults (age 65–88 years) were separated into 1) fast-speed exercise (Fast-group), 2) slow-speed exercise (Slow-group), and 3) no exercise (Control-group) groups. Participants in the exercise groups performed 30–45 repetitions of knee-extension and sit-to-stand exercises 3 times a week for 8 weeks with different exercise speed between the groups. Before and after the intervention period, the following variables were measured: Isotonic power, isometric strength, twitch contractile properties, muscle-activity, -architecture, and -quality, neuromuscular fatigue resistance of the knee extensors, and thigh muscle volume. ResultsPeak power was increased in both the Fast-group (+24 %, P < 0.01, d = 0.65) and Slow-group (+12 %, P < 0.05, d = 0.33) but not in the Control-group. Training increased pennation angle of the vastus lateralis in both the Fast-group (+8 %, P < 0.01, d = 0.42) and Slow-group (+8 %, P < 0.01, d = 0.42), while only the Fast-group showed increase in pennation angle of the rectus femoris (+12 %, P < 0.01, d = 0.64) and thigh muscle volume (+16 %, P < 0.01, d = 0.52). There was no time × group interaction effect for the other neuromuscular measures. ConclusionsUnsupervised, body mass- and home-based resistance training performed at either fast or slow speeds can improve muscle power in older adults, while fast-speed exercise may be preferable over slow-speed owing to the relatively greater improvement of muscle-power, −volume, −architecture, and better time efficiency.

Abstract 15316: Neonatal Mesenchymal Stem Cells Ameliorate Cardiac Fibrosis and Diastolic Dysfunction in HFpEF via Expanding CD4 + CD25 + Foxp3 + T regs

Introduction: We have demonstrated that neonatal mesenchymal stem cells (nMSCs) extracted from human neonatal cardiac tissues and their exosomes, secretome, potently decrease cardiac fibrosis and improve cardiac function in the rat model of myocardial infarction. CD4 + CD25 + Foxp3 + (forkhead box 3) regulatory T cells (T regs ) are recently shown to regulate the formation of cardiac fibrosis in myocardial infarction. How nMSCs and secretome affect cardiac fibrosis and T regs of animals with heart failure with preserved ejection fraction (HFpEF) is unknown. Hypothesis: We hypothesized that nMSCs and secretome ameliorate cardiac fibrosis and diastolic dysfunction in HFpEF by regulating cardiac T regs . Methods: C57BL/6 mice were fed 60% high-fat diet and L-NAME to induce HFpEF or normal chow as a control. Left ventricular morphology and function were evaluated using an echocardiography. After the mice developed HFpEF, the animals were injected 10 6 nMSCs, 10 mg/kg of secretome, or equivalent amounts of vehicle as a control via tail vein. Myocardial fibrosis was quantified in trichrome-stained heart sections. Circulating and cardiac T regs were measured on a FACSCanto II cytometer. Fingolimod at a dose of 3 mg/kg was intraperitoneally injected daily for 18 days. Results: C57BL/6 mice fed high-fat diet and L-NAME for 5 weeks developed obesity, myocardial fibrosis, left ventricular hypertrophy and diastolic dysfunction (increases in mitral E/e’ ratio), and exercise intolerance with &gt; 50% of left ventricular ejection fraction. Compared to the HFpEF mice receiving vehicle, either nMSCs or secretome significantly decreased cardiac interstitial fibrosis and mitral E/e’ ratio and increased cardiac CD4 + CD25 + FoxP3 + T regs from 1 to 4 weeks post treatment. Importantly, either nMSCs or secretome enhanced the exercise speed and distance of the HFpEF mice. Fingolimod significantly decreased circulating and cardiac T regs in the HFpEF mice, which blocked the beneficial effects of nMSCs and secretome on cardiac fibrosis and diastolic function. Conclusions: nMSCs and secretome ameliorate cardiac fibrosis and diastolic dysfunction by expanding CD4 + CD25 + FoxP3 + T reg s in HFpEF. These results suggest that nMSCS and secretome have high therapeutic potential for HFpEF.

Intervention strategies with muscle strengthening exercises to improve walking speed in the older adults

The fact of performing physical activity is of vital importance and if a muscle strengthening exercise program plan is added to this, it is even more beneficial for the health of our body. The aim of this study was to determine if muscle strengthening exercise helps improve walking speed in these people. Information was collected from the main scientific bases such as PubMed, Google Scholar, Scopus, Scielo, Elsevier. For the investigation of the information, the following descriptors of health sciences were used: Gait; Walking speed; Pass test; Exercise techniques with movement; old man; Exercise with therapy. The inclusion criteria were the articles that were within the period 2017-2022, in the English, Portuguese and Spanish languages. 30 articles were incorporated into this review article. In these articles, information was found on the speed of walking and muscle strength exercises in the elderly. With the information collected, it is concluded that the application of a program of muscle strengthening exercises in the lower limb helps to improve the speed of walking in older adults.

Two‐Minute Drill

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Isometric handgrip exercise speeds working memory responses in younger and older adults.

Physiological arousal affects attention and memory, sometimes enhancing and other times impairing what we attend to and remember. In the present study, we investigated how changes in physiological arousal-induced through short bursts of isometric handgrip exercise-affected subsequent working memory performance. A sample of 57 younger (ages 18-29) and 56 older (ages 65-85) participants performed blocks of isometric handgrip exercise in which they periodically squeezed a therapy ball, alternating with blocks of an auditory working memory task. We found that, compared with those in a control group, participants who performed isometric handgrip had faster reaction times on the working memory task. Handgrip-speeded responses were observed for both younger and older participants, across working memory loads. Analysis of multimodal physiological responses indicated that physiological arousal increased during handgrip. Our findings suggest that performing short bouts of isometric handgrip exercise can improve processing speed, and they offer testable possibilities for the mechanism underlying handgrip's effects on performance. The potential for acute isometric exercise to temporarily improve processing speed may be of particular relevance for older adults who show declines in processing speed and working memory. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Hemodynamic response to different contractile speeds of resistance exercise in adults with sarcopenic obesity

This study aimed to compare the effects of high-speed and low-speed resistance exercise on hemodynamics in adults with sarcopenic obesity. We hypothesized that high-speed resistance exercise induces greater/longer cardiovascular stress than low-speed resistance exercise. Forty-five individuals with sarcopenic obesity (64.0±6.0 years) were randomized to the low-speed resistance exercise group (LSRE; n=24) and the high-speed resistance exercise group (HSRE; n=21). All participants performed one-session of resistance exercises [squatting, chest press, and upright row; 3 sets of 10 repetitions at 60% of 1 repeated maximum]. Participants in the LSRE group performed the exercises with a 4:4 second concentric-eccentric contraction cycle controlled by a metronome while participants in the HSRE group performed the exercise with a 1:4 second concentric-eccentric contraction cycle. Systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), and arterial stiffness (brachial-ankle pulse wave velocity; baPWV) were determined before exercise (resting), immediately after exercise (P0), 15-min after exercise (P15), and 30-min after exercise (P30). Two-way repeated measure analysis of variance was used to examine the effect of different contractile speeds of resistance exercise on outcome variables. The significant level was set at 0.05. We found that the HR at P0 was higher than the resting values for both groups, with 10.9 bpm and 14.0 bpm of increases for the LSRE group and HSRE group, respectively. HR was back to the resting level at P15 in the LSRE group; however, HR was back to the resting level until P30 in the HSRE group. For both groups, SBP was significantly higher at P0 compared to resting (12.5 mmHg of increase for the LSRE group and 11.9 mmHg of increase for the HSRE group) and back to the resting level at P15. PWV at P0 was higher than the resting and back to the resting level at P15 in the LSRE group. PWV levels did not change with exercise in the HSRE group (p&gt;0.05). DBP did not change significantly with exercise in both groups (p&gt;0.05). In conclusion, the influence of HSRE on HR is longer than that of LSRE. LSRE, but not HSRE, results in transient changes in arterial stiffness in adults with sarcopenic obesity. This study was supported by the Ministry of Science and Technology, Taiwan [grant numbers: MOST-109-2314-B-010 -036 -MY3 (Chen, C.N.)]. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Fast, non-eccentrically loaded exercise worsens tendinopathic healing responses in a murine model.

To advance the understanding of how alterations in exercise speed and grade (flat vs 17° incline or decline) affect the quality of tendon healing, and to determine if a biomarker relationship exists between serum levels of a ColX breakdown product (CXM) and animals exposed to treadmill running protocols. 35 male mice (C57BL/6J), 8 weeks of age. Mice were preconditioned on a treadmill for 14 days. Tendinopathy was then induced by 2 intra-tendinous TGFβ1 injections followed by randomization into 7 exercise groups. Exercise capacity and objective gait analysis were measured weekly. Mice were euthanized and histopathologic analysis and evaluation of serum CXM levels were performed. Statistics were conducted using a 2-way ANOVA (exercise capacity), Mixed Effects Model (gait analysis, effect of preconditioning), and 1-way ANOVA (gait analysis, the effect of injury, and rehabilitation normalized to baseline; CXM serum analysis), all with Tukey post hoc tests and significance set to P < .05. Exercise at a fast-flat speed demonstrated inferior tendinopathic healing at the cellular level and impaired stance braking abilities, which were compensated for by increased propulsion. Mice exposed to exercise (at any speed or grade) demonstrated higher systemic levels of CXM than those that were cage rested. However, no ColX immunostaining was observed in the Achilles tendon or calcaneal insertion. Exercise at a fast speed and in absence of eccentric loading components (incline or decline) demonstrated inferior tendinopathic healing at the cellular level and impaired braking abilities that were compensated for by increased propulsion.

Privacy-Preserving Personalized Fitness Recommender System P 3 FitRec : A Multi-level Deep Learning Approach

Recommender systems have been successfully used in many domains with the help of machine learning algorithms. However, such applications tend to use multi-dimensional user data, which has raised widespread concerns about the breach of users’ privacy. Meanwhile, wearable technologies have enabled users to collect fitness-related data through embedded sensors to monitor their conditions or achieve personalized fitness goals. In this article, we propose a novel privacy-aware personalized fitness recommender system. We introduce a multi-level deep learning framework that learns important features from a large-scale real fitness dataset that is collected from wearable Internet of Things (IoT) devices to derive intelligent fitness recommendations. Unlike most existing approaches, our approach achieves personalization by inferring the fitness characteristics of users from sensory data, minimizing the need for explicitly collecting user identity or biometric information, such as name, age, height, and weight. Our proposed models and algorithms predict (a) personalized exercise distance recommendations to help users to achieve target calories, (b) personalized speed sequence recommendations to adjust exercise speed given the nature of the exercise and the chosen route, and (c) personalized heart rate sequence to guide the user of the potential health status for future exercises. Our experimental evaluation on a real-world Fitbit dataset demonstrated high accuracy in predicting exercise distance, speed sequence, and heart rate sequence compared with similar studies. 1 Furthermore, our approach is novel compared with existing studies, as it does not require collecting and using users’ sensitive information. Thus, it preserves the users’ privacy.

Effects of Speed Differences in Treadmill Walking on Parkinson’s Disease Patients

[Purpose] To examine the effects of speed differences in treadmill walking exercise on Parkinson’s disease (PD) patients. [Participants and Methods] The maximum walking speed, stride length, gait rate, and lateral, vertical, and anterior-posterior RMS during walking were compared among 23 patients with PD. [Results] Walking speed, stride length, walking rate, and vertical and anterior-posterior root mean square (RMS) significantly improved after maximal and comfortable treadmill walking compared to before. Lateral RMS significantly improved after comfortable treadmill walking compared to before. There were no significant differences in the rates of change of the items between before and after maximal and comfortable treadmill walking. [Conclusion] There was no difference in the immediate effect of the speed of treadmill walking exercise on the walking ability of PD patients; both speeds improved walking ability.

Supplemental Material for Isometric Handgrip Exercise Speeds Working Memory Responses in Younger and Older Adults

Supplemental Material for Isometric Handgrip Exercise Speeds Working Memory Responses in Younger and Older Adults

Combining a non-immersive virtual reality gaming with motor-assisted elliptical exercise increases engagement and physiologic effort in children

Virtual reality (VR) gaming is promising in sustaining children’s participation during intensive physical rehabilitation. This study investigated how integration of a custom active serious gaming with a robot-motorized elliptical impacted children’s perception of engagement (Intrinsic Motivation Inventory), physiologic effort (i.e., exercise speed, heart rate, lower extremity muscle activation), and joint kinematics while overriding the motor’s assistance. Compared to Non-VR condition, during the VR-enhanced condition participants’ perceived engagement was 23% greater (p = 0.01), self-selected speed was 10% faster (p = 0.02), heart rate was 7% higher (p = 0.08) and muscle demands increased. Sagittal plane kinematics demonstrated only a small change at the knee. This study demonstrated that VR plays an essential role in promoting greater engagement and physiologic effort in children performing a cyclic locomotor rehabilitation task, without causing any adverse events or substantial disruption in lower extremity joint kinematics. The outcomes of this study provide a foundation for understanding the role of future VR-enhanced interventions and research studies that weigh/balance the need to physiologically challenge a child during training with the value of promoting task-related training to help promote recovery of walking.

The Effect of Aerobic Exercise on Recovery in Adolescents who Report Emotional and Cognitive Symptoms after Sport-Related Concussion

<h3>Research Objectives</h3> Aerobic exercise speeds recovery from sport-related concussion (SRC) and reduces the incidence of prolonged symptoms; however, evidence for emotional and cognitive symptom recovery among this population is limited. This study determined whether aerobic exercise following SRC improved recovery in adolescents who reported emotional and cognitive symptoms. <h3>Design</h3> Meta-analysis of two published randomized control trials. <h3>Setting</h3> Four sports medicine clinics specializing in concussion management. <h3>Participants</h3> Male and female adolescents (13-18 years, n=212, 59% male) who were diagnosed with SRC within ten days of injury and reported emotional or cognitive symptoms on the Post-Concussion Symptom Scale (PCSS) or Post-Concussion Symptom Inventory (PCSI). <h3>Interventions</h3> Participants were assigned to individualized aerobic exercise (n=109) or to a placebo-like stretching program (n=103). <h3>Main Outcome Measures</h3> Recovery from SRC, defined as a participant having no concussion-like symptoms, a normal physical examination, and a return to normal exercise tolerance. <h3>Results</h3> A fixed-effects meta-analysis determined the probability of recovery between aerobic vs. stretching exercise. Participants with high emotional (≥1/24), low emotional (=0/24) and low cognitive (≤10/30) symptom scores had a higher probability of recovering when prescribed aerobic exercise, respectively (61% p=0.028, 60% p=0.030, 47%, p=0.025). However, results were inconclusive regarding recovery in those with high cognitive (>10/30) symptoms when prescribed aerobic exercise (p=0.175). <h3>Conclusions</h3> Our data suggest that participants with emotional symptoms and with low cognitive symptom burden benefited from aerobic exercise more than from stretching. Clinicians ideally should manage SRC based on individual clinical profiles and should recommend aerobic exercise for patients with significant emotional symptoms. Patients with high cognitive symptoms also benefit from aerobic exercise but appear to need specialized intervention. <h3>Author(s) Disclosures</h3> Authors have no disclosures.

Effect of caffeine on mitochondrial biogenesis in the skeletal muscle - A narrative review.

Caffeine is one of the most widely used substances as recreational drug for performance-enhancement in sport, underpinned by a strong evidence base. Although the effects of caffeine are widely investigated within the scope of performance physiology, the molecular effects of caffeine within skeletal muscle remain unclear. Evidence from invitro and invivo models suggest that caffeine regulates the glucose metabolism in the skeletal muscle. Moreover, caffeine seems to stimulate CaMKII, PPARδ/β, AMPK and PGC1α, classical markers of exercise-adaptations, including mitochondrial biogenesis and mitochondrial content. This review summarizes evidence to suggest caffeine-effects within skeletal muscle fibers, focusing on the putative role of caffeine on mitochondrial biogenesis to explore whether caffeine supplementation might be a strategy to enhance mitochondrial biogenesis.

The Quality of Organizational Agility in Crisis Management at the Football Association in Jordan: Coaches' Perspective

The study aims to pinpoint the effectiveness of organizational agility in crisis management at the Jordan Football Association. To achieve the objectives of the study, the descriptive approach is used, and a questionnaire scale is prepared as a measurement instrument. The study population consists of all the (60) male and female football coaches at the Jordan Football Association. After collecting the data and analyzing them statistically using T-test and ANOVA to find out the gender, the academic degree, and experience differences regarding organizational agility in crisis management, the findings indicate that the issue of applying the concept of organizational agility in crisis management in the Association is of a medium degree. The findings also show that there are no statistically significant differences for the variable of gender, experience, and academic degree exception for the dimension of practice agility, and in favor of the higher academic degree. In light of the aforesaid findings, the study recommends developing organizational and educational structures and regulations in a method that reduces bureaucracy, enhancing the independence of the departments and committees working in the Association to exercise speed and flexibility in decision-making, and improving the capabilities of directors of departments and committees in the Football Association in pinpointing and applying the concept of organizational agility and work practice.

Adolescents with Sport-Related Concussion Who Adhere to Aerobic Exercise Prescriptions Recover Faster.

There is growing evidence that subsymptom threshold aerobic exercise speeds recovery from sport-related concussion (SRC). It is not known whether there is a direct relationship between adherence to a personalized exercise prescription and recovery or if initial symptom burden affects adherence to the prescription. This study was a planned secondary analysis of one arm of a randomized controlled trial. Male and female adolescent athletes (age 13-18 yr) presenting within 10 d of SRC were given aerobic exercise prescriptions based on their heart rate threshold at the point of exercise intolerance on a graded treadmill test. Adherence was determined objectively with HR monitors and compared against time to recovery. Participants who completed at least two-thirds of their aerobic exercise prescription were considered to be adherent. Sixty-one percent of adolescents met the adherence criterion. Those who were adherent were more symptomatic and were more exercise intolerant at their initial visit, yet they recovered faster than those who were not adherent (median recovery time, 12 (interquartile range, 9-22) d vs 21.5 (interquartile range, 13-29.8) d; P = 0.016). On linear regression, adherence during week 1 was inversely related to recovery time ( β = -0.002 (-0.003, 0.0), P = 0.046) and to initial exercise tolerance ( β = -0.886 (-1.385, -0.387), P < 0.001), but not to initial symptom severity ( β = 0.545 (-0.232, 1.323), P = 0.146). No adverse events or near misses were reported. Adherence to individualized subsymptom threshold aerobic exercise within the first week of evaluation is associated with faster recovery from SRC. The data suggest that initial degree of exercise intolerance, but not initial symptom severity, affects adherence to aerobic exercise prescribed to adolescents within 10 d of SRC.

A Fitness-Fatigue Model of Performance in Peripheral Artery Disease: Predicted and Measured Effects of a Pain-Free Exercise Program.

Banister impulse-response (IR) model estimates the performance in response to the training impulses (TRIMPs). In 100 patients with peripheral artery disease (PAD), we tested by an IR model the predictability of the effects of a 6-month structured home-based exercise program. The daily TRIMPs obtained from prescribed walking speed, relative intensity and time of exercise determined the fitness-fatigue components of performance. The estimated performance values, calculated from the baseline 6-min and pain-free walking distance (6MWD and PFWD, respectively) were compared with values measured at visits through regression models. Interval pain-free walking at controlled speed prescribed during circa-monthly hospital visits (5 ± 1) was safely performed at home with good adherence (92% of scheduled sessions, 144 ± 25 km walked in 50 ± 8 training hours). The mean TRIMP rose throughout the program from 276 to 601 a.u. The measured 6MWD and PFWD values increased (+33 m and +121 m, respectively) showing a good fit with those estimated by the IR model (6MWD: R2 0.81; PFWD: R2 0.68) and very good correspondence (correlation coefficients: 0.91 to 0.95), without sex differences. The decay of performance without training was estimated at 18 ± 3 weeks. In PAD, an IR model predicted the walking performance following a pain-free exercise program. IR models may contribute to design and verify personalized training programs.

Real options, risk aversion and markets: A corporate finance perspective

We analyze how the presence of financial markets affects the optimal exercise of real options for a risk averse agent. Extending the results of Shackleton and Sodal (2005), we characterize the optimal exercise rule in terms of a benchmark portfolio, even for the case of an incomplete market, facilitating the minimal martingale measure. We unambiguously characterize the effect of idiosyncratic risk on the speed of exercise of the option. We further show that systematic risk can accelerate execution and reduce the value of a call-type option, in contrast with the standard view that both value and execution threshold are increasing in volatility.

Effects of Walking Speed on Total and Regional Body Fat in Healthy Postmenopausal Women.

Introduction: This study had two aims: (1) To confirm the efficacy of exercise speed and impulse (session duration at a given speed) to produce total and abdominal fat loss in postmenopausal women, and (2) compare the exercise speed and impulse necessary for the stimulation of fat loss to the suppression of bone mineral loss. Of special interest was to compare these parameters of exercise on fat loss in the same study and with the same subjects where they were found to suppress bone mineral loss. We hypothesized that (1) more total fat will be lost with slow walking and a longer impulse than with fast speed and shorter impulse, and (2) more abdominal subcutaneous (SC) and visceral fat (VF) will be lost with fast walking speed. Materials and Methods: Fat loss and suppression of bone mineral loss were measured in the same 25 subjects after 15 weeks, and fat measurements were also taken after 30 weeks in 16 residual subjects. Study parameters were walking a 4.8 km distance 4 days/week at either 6.6 km/h (120% of ventilatory threshold (VT)) or at 5.5 km/h (101.6% of VT) and expending 300 kcal/session. Body composition (fat and lean body mass, LBM) was measured with dual-energy X-ray absorptiometry (DXA) and anthropometric methods. Results: Slow walkers in the residual group progressively lost a significant percent of total body fat over 30 weeks while no such loss occurred after 15 weeks in fast walkers in either group, supporting hypothesis 1. However, the 20% higher starting body fat in 16 residual slow relative to fast subjects suggests that exercise fat loss is greater in overweight than in lean subjects. In fast walkers, fat loss occurred after 30 weeks of training. Hypothesis 2 was not supported as both speeds led to equal VF loss in 30-week group as estimated by waist circumference (CF) confirming that VF responds to the magnitude of energy expenditure and not the walking speed. Conclusions: Total body fat is lost through walking at all speeds, but the change is more rapid, clear, and initially greater with slow walking in overweight subjects. A longer exercise impulse at a lower speed in our study initially produced greater total fat loss than a shorter one with fast walking speed. This was reversed in comparison to how the same exercise in the same subjects suppressed bone mineral loss. Data from other studies indicate that longer impulses may promote greater fat loss at both slow and high exercise speeds, and our study providing only a 4.8 km walking distance may have limited the walking impulse and the magnitude of fat loss. Increased exercise energy expenditure at either walking speed produces equivalent declines in visceral fat in postmenopausal women, and with sufficiently long impulses, should reduce disabilities associated with central obesity.