Non-invasive vagus nerve stimulation in a hungry state decreases heart rate variability.

Vagus nerve signals from the gut to brain carry information about nutrients and drive food reward. Such signals are disrupted by consuming large amounts of high-calorie foods, necessitating greater food intake to elicit a similar neural response. Non-invasive vagus nerve stimulation (nVNS) via a branch innervating the ear is a candidate treatment for obesity in humans. There is disagreement on the optimal location of nVNS in the ear for experimental and clinical studies. There are also no studies comparing nVNS in hungry and post-prandial states. We aimed to compare ear position(s) for nVNS and explore the effects of nVNS during hungry and post-prandial states on proxies for autonomic outflow (heart-rate variability) and efferent metabolism (gastric wave frequency and resting energy expenditure). In a within-subject design, 14 participants (10 women, on average 29.4 +/- 6.7 years old) received nVNS in four different locations (cymba conchae, tragus, earlobe, or tragus AND cymba conchae) on separate days. In each session, participants were asked to consume a palatable chocolate flavored milk. With electrography on the abdomen and indirect calorimetry in a canopy, we measured electro-cardiogram, electro-gastrogram and resting energy expenditure for 15 min before and at least 35 min after consumption of the palatable drink. We also collected ratings of the palatable drink and internal and other states. Pre-drink consumption (in a hungry state) we observed no differences in the effect of location of acute nVNS on resting energy expenditure and gastric wave measures. However, nVNS in cymba conchae decreases heart-rate variability (relative to sham) and ratings of how much participants want to consume the drink (relative to tragus AND cymba conchae and a trend relative to sham). After drink consumption and with continued nVNS, gastric wave frequency is unchanged, and resting energy expenditure increases regardless of stimulation location. Heart-rate variability decreases in all locations, except cymba conchae. We also observe a trend for an increase in gastric wave amplitude in late post-drink consumption time-points in cymba conchae. We observe no support for the combined stimulation of tragus AND cymba conchae being more effective than either of the individual locations. These results suggest that nVNS in the cymba conchae in a hungry state has a similar acute effect on vagal tone as food consumption: to decrease heart rate variability. This effect then negates the usual postprandial effects of a decrease in heart rate variability as seen in the other nVNS locations. These preliminary observations suggest that nVNS in cymba conchae may act primarily on vagal afferent autonomic (and only modestly on metabolic output) in a similar way as food consumption does.

Alterations in energy consumption and plantar pressure distribution during walking in young adults with patellofemoral pain syndrome.

OBJECTIVE: The aim of this study was to determine the alterations of walking energy expenditure and plantar pressure distribution in young adults with patellofemoral pain syndrome (PFPS). METHODS: Thirty five individuals (mean age: 21.31 ± 1.76) with PFPS constituted the patient group and forty healthy participants (mean age: 21.40 ± 2.11) the control group. Preferred walking speeds (PWS) were determined on the over ground. Individuals walked on a treadmill for 7 min at their PWS and 30% above PWS and oxygen consumption was recorded via a metabolic analyzer. Net oxygen consumption was calculated for each walking trial. Borg scale was applied to assess perceived exertion during walking trial. Plantar pressure distributions were measured by a pedobarography device. Plantar area was subdivided into six zones to evaluate the dynamic plantar pressure data. RESULTS: The mean PWS of PFPS and control groups were 4.69 ± 0.51 and 4.52 ± 0.60 km/h, respectively (p > .09). No significant difference was observed in energy expenditure during walking at PWS between 2 groups while oxygen consumption during 30% above PWS was higher in patient group (18.72 ± 3.75 and 16.64 ± 3.27) (p = .007). Net oxygen consumption was also found to be higher in PFPS group (15.12 ± 3.62 and 13.04 ± 3.24) (p = .005). The mean Borg scores were significantly higher in PFPS group at each walking trials (p < .001). No statistically significant difference was found between weight distribution (%) of symptomatic and nonsymptomatic extremity (50.45 ± 3.92% and 49.56 ± 3.93%, respectively) (p = .509). Dynamic pedobarography parameters were not different between 2 groups, and also between symptomatic and nonsymptomatic extremities (p > .05). CONCLUSION: Although, rate of perceived exertion and energy expenditure during walking at 30% above PWS are affected negatively in young adults with PFPS, we may speculate that energy consumption and plantar pressure distribution can be compensated by a physiologic adaptation mechanism during walking at PWS. LEVEL OF EVIDENCE: Level III, Therapeutic Study.

Resting energy expenditure in normal-weight and overweight/obese subjects was similar despite elevated sympathovagal balance.

OBJECTIVE: Alterations in the autonomic nervous system (ANS) may cause impairment in the metabolic processes that can lead to weight gain. The purpose of this study was to determine the difference between the resting energy expenditure (REE) and the resting ANS activity in overweight/obese and normal-weight healthy subjects. METHOD: Group 1 consisted of 18 subjects with BMI > 25 kg/m², and 20 subjects with BMI ranging from 20 to 25 kg/m² formed group 2. Measurements of low-frequency (LF) and high-frequency (HF) power components expressed in normalized units (LFnu, HFnu) and LF/HF ratio were assessed for analysis of heart rate variability, and simultaneously REE measurement was performed. RESULTS: The mean LFnu (27.2% increased) and the LF/HF were higher and the mean HFnu was lower (29.9% decreased) in group 1 than in group 2 (p < 0.01). Although a statistical difference was observed in REE between groups, REE per kilogram corrected for fat-free mass (REE(FFMcorr)) was 21.47 ± 2.92 kcal/day/kg in group 1, and 21.56 ± 1.90 kcal/day/kg in group 2, and this difference was not statistically significant (p > 0.05). CONCLUSION: We concluded that REE(FFMcorr) in overweight/obese and normal-weight subjects were similar despite elevated sympathovagal balance in overweight/obese individuals, and REE(FFMcorr) should be used to avoid misestimating the REE in obese and normal-weight subjects.

Anterior cruciate ligament reconstruction improves the metabolic energy cost of level walking at customary speeds.

PURPOSE: The metabolic energy cost of walking is altered by pathological changes in gait. It is thought that anterior cruciate ligament (ACL) deficiency alters the energy requirement for level walking through its effect on gait pattern. In this study, it is hypothesised that the metabolic energy cost of walking would improve after ACL reconstruction. METHODS: Eight patients who were undergoing ACL reconstruction for an isolated rupture were included in this prospective study. Clinical examinations, Lysholm scores and metabolic tests were performed preoperatively and at 3, 6 and 12 months after ACL reconstruction using autologous quadruple hamstring tendons. For the metabolic evaluation, net oxygen cost was calculated while walking on a treadmill at 50-, 70- and 90-m/min velocities. A two-way factorial ANOVA was performed in order to evaluate the primary effects and interactions of the time point and velocity variables on net oxygen cost. RESULTS: All patients had positive Lachman and anterior drawer tests preoperatively that became negative postoperatively and remained negative until the last follow-up point. The mean preoperative Lysholm score was 66, whereas the mean postoperative follow-up scores were 85, 91 and 94, respectively. The interaction between follow-up time point and velocity was not significant. Regardless of the selected velocity, the net oxygen cost was lower than that at preoperative levels at each postoperative time point (p < 0.05). CONCLUSION: The results of the present study indicate that the energy cost of level walking in chronic ACL-deficient patients improves after ACL reconstruction. Cause-effect-based studies with correlation evaluations that compare kinetic, kinematic and electromyographic data and metabolic cost calculations should facilitate more accurate analyses. LEVEL OF EVIDENCE: Therapeutic study, Level 4.

A new upper extremity sparing non-weight bearing orthosis.

OBJECTIVES: Axillary and forearm crutches are commonly utilized in the treatment of foot and ankle injuries. In order to decrease the energy expenditure during mobilization, to prevent upper extremity complications, and to let the upper extremity free for other usages, we designed a new orthosis. The study is conducted to compare walking energy parameters of this newly designed orthosis with the axillary and forearm crutches. MATERIALS AND METHODS: 10 healthy young male volunteers walked on treadmill with three different orthoses in randomized order. Oxygen expenditure, oxygen cost, rate of perceived exertion (Borg scale), and observer stability assessment were analyzed. RESULTS: Concerning oxygen consumption, perceived exertion, and observer stability assessment, the new device was found superior to the other devices (P<0.05). The new orthosis was superior to forearm crutches concerning oxygen cost (P=0.027) but not significantly different from the axillary crutches (P=0.062). DISCUSSION: Compared to frequently used orthoses, the developed device provides mobilization using less or similar amount of energy. Additionally it spares one upper extremity to be used for other activities.

Prevalence of respiratory abnormalities and pneumoconiosis in dental laboratory technicians.

A preventable occupational disease, pneumoconiosis that is often widespread on to a very kind of quartz, carbon and metal dust exposed work place.The data for the prevalence of pneumoconiosis and respiratory findings among dental laboratory technician is insufficient. The aim of this study is to determine the prevalence of pneumoconiosis and respiratory findings among dental laboratory technicians, working in province of Sivas. For this reason all the dental technicians (except 2, totally 36) participated in the study. A questionnaire which contains demographic characteristics, work conditions and symptoms were applied to all participants. Also spirometric measurements and chest x-rays were performed. The x-rays of dental technicians were evaluated by a radiologist and a chest disease specialist according to the ILO-2000 classification of pneumoconiosis. Almost half of the all participants have dyspnea and phlegm expectoration. The prevalence of pneumoconiosis was 5 (13.8%) among 36 dental technicians. There were no statistically significant differences between two groups with regard to respiratory symptoms. Values of lung function parameters of the dental technician group were not significantly different from those of control group except FEV(1). In conclusion, dental laboratory technicians are at significant risks for occupational respiratory diseases so the primary prevention rules are essential for these work places.

Determination of preferred walking speed on treadmill may lead to high oxygen cost on treadmill walking.

The energy consumption of walking relates to the intensity of physical effort and can be affected by the alterations in walking speed. Therefore, walking speed can be accepted as a crucial, determinant of energy consumption measurement for a walking test. We aimed to investigate the differences in preferred walking speed (PWS) determined both on overground and on a treadmill and, to measure walking energy expenditure and spatio-temporal parameters of gait on a treadmill at both, speeds. Participants (n=26) walked on a treadmill at two pre-determined speeds for 7 min while, indirect calorimetry measurements were being performed. Spatio-temporal parameters were collected, by video-taping during each walking session on a treadmill. The average overground preferred walking speed (O-PWS) was 85.96+/-12.82 m/min and the average treadmill preferred walking speed (T-PWS), was 71.15+/-13.85 m/min. Although T-PWS was lower, oxygen cost was statistically higher when, treadmill walking at T-PWS (0.158+/-0.02 ml/kg/m) than when the treadmill walking at O-PWS, (0.1480+/-0.02 ml/kg/m). Cadence (127+/-9.13 steps/min), stride (134.02+/-14.09 cm) and step length (67.02+/-6.90 cm) on the treadmill walking at O-PWS were significantly higher than cadence (119+/-10 steps/min), stride (117.96+/-14.38 cm) and step length (59.13+/-7.02 cm) on the treadmill walking at TPWS. In conclusion, walking on treadmill using O-PWS is more efficient than walking on treadmill using TPWS, in walking tests. Since using T-PWS for treadmill walking tests overestimates the oxygen cost of walking, O-PWS should be used for oxygen consumption measurement during treadmill walking tests.

Basal metabolic rate and autonomic nervous system dysfunction in men with spinal cord injury.

OBJECTIVES: The purpose of this study was to determine the relationship between autonomic nervous system dysfunction and basal metabolic rate (BMR), and the effect of spasticity on basal metabolic rate. RESEARCH METHOD AND PROCEDURES: Twenty men (11 paraplegic and 9 tetraplegic) with American Spinal Injury Association (ASIA)-A and -B grade chronic spinal cord injury (SCI) participated in this study. Total body fat mass and lean tissue mass were measured in all participants using DXA by standard methods. Patients were allocated into 2 groups to determine the effect of autonomic nervous system dysfunction on BMR: Group I (T6 and upper-level injuries with history of autonomic dysreflexia) and Group II (T7 and lower-level injuries without history of autonomic dysreflexia). Measurements of BMR were determined by indirect calorimetry under standardized conditions. RESULTS: There were 13 patients in Group I and 7 patients in Group II and the difference between these two in terms of time since injury, BMI, age, weight, lean tissue mass, BMR, and BMR/kg were not significant. CONCLUSION: We concluded that autonomic nervous system dysfunction does not affect BMR, and it might be ignored in considering energy needs in spinal cord injury.

The effect of hinged ankle-foot orthosis on gait and energy expenditure in spastic hemiplegic cerebral palsy.

PURPOSE: To assess the effectiveness of a hinged ankle-foot orthoses on gait impairments and energy expenditure in children with hemiplegic cerebral palsy (CP) whom orthoses were indicated to control equines. METHOD: Eleven children (seven males, four females) who had a diagnosis of hemiplegic cerebral palsy were included in the study. Each child underwent gait analysis and energy consumption studies with and without ankle-foot orthosis (AFO). The AFOs were all custom-made for the individual child and had plantarflexion stop at 0 degrees with no dorsoflexion stop. The Vicon 512 Motion analysis system was used for gait analysis. Walking energy expenditure measurements were done with breath by breath method using an open-circuit indirect calorimeter (Vmax 29c, Sensormedics, USA). All tests were carried out on the same day with enough resting period. RESULTS: AFO application, as compared with the barefoot condition improved walking speed, stride length and single support time. Double support time was decreased significantly with AFOs and no change in cadance. Ankle dorsiflexion at initial contact, midstance and midswing showed significiant increase. Knee flexion at initial contact was decreased and no significant change in maximum knee extension at stance and maximum knee flexion at swing was obtained. The oxygen consumption was significantly reduced during AFO walking. CONCLUSION: The hinged AFO is useful in controlling dynamic equinus deformity and reducing the energy expenditure of gait in children with hemiplegic spastic cerebral palsy.

[The prevalence of sleep related disorders among the drivers and it's relation with traffic accidents]. / Sürücülerde uyku ile ilgili hastaliklarin prevalansi ve trafik kazalari ile iliskisi.

Studies consistently show that patients with sleep related diseases (SRD) have higher accident rates. Polysomnography (PSG) is the gold standard for the diagnosis of SRD. Sleep habits questionnaires are also useful tool for research of the prevalence of SRD on large populations. The aim of this study is to investigate the prevalence of SRD and SRD related traffic accidents on the whole population of professional drivers in Sivas city. A questionnaire that includes questions about drivers' background such as how long they have been driving, if they had any accidents, and if they drive just in Sivas city or inter state. This questionnaire composed of 50 questions about SRD and was asked to drivers answer them face to face. Three hundred forty male drivers participated for this study. Their mean age was 39.5+/-9.3 (21-68) years. The mean driving duration was 13.3+/-7.9 years. The percentage of drivers who drove in Sivas was 52.1% and 47.9% of the drivers drove inter state. The percentage of drivers who had at least one accident was 36.3%. The prevalence of habitual snoring, insomnia, sleep apnea, nocturnal myoklonus were 41.2%, 39.1%, 32.9%, and 33.6% respectively. The traffic accident Odds ratio was 1.619 for drivers with habitual snoring (95% CI, 1.034 to 2.536, p=0.02). In conclusion, this study found out that drivers with habituel snoring seems to have tendency (approximately 2-folds) of involving in traffic accidents than drivers who do not have habituel snoring. Polysomnography of candidate drivers with sleep disordered symptoms has to be logical before giving to driving license.

[The comparison of the result of exercise bronchoprovocation test and methacholine bronchoprovocation test in athletes]. / Sporcularda metakolin ve egzersiz bronkoprovokasyon testleri sonuçlarinin karsilastirilmasi.

The excess contraction respond of the bronchiols to the specific and non-specific agent is called bronchial hyperresponsiveness. In our study we compared the result of exercise bronchoprovocation test and methacholine bronchoprovocation test in athletes (group I) and in sedentary subjects (group II). The subjects that their age, height, weight and environmental status of the test room (temperature and humidity) were not statistically different, they gave statistically different respond to the methacholine bronchoprovocation test (p< 0.05). Their respond to exercise bronchoprovocation test was similar and there was no statistically difference between two groups (p> 0.05). In group I, there was a correlation in the result of exercise bronchoprovocation test and methacholine bronchoprovocation test (r= 0.60, p< 0.05), but in group II there was no correlation in this two tests. The parameters that we use for evaluation of the allergic status (total IgE, eosinophil count, number of atopic subject in groups) were not statistically different (p> 0.05). In both two groups there was a statistically different respond in the result of exercise bronchoprovocation test and methacholine bronchoprovocation test. These findings suggests that methacholine bronchoprovocation test is a more sensitive test for the diagnosis of BHR in athletes and sedantery subjects than exercise bronchoprovocation test.