Mathias Krogh Poulsen

Estimation of Energy Expenditure during Treadmill Exercise via Thermal Imaging.

PURPOSE Noninvasive imaging of oxygen uptake may provide a useful tool for the quantification of energy expenditure during human locomotion. A novel thermal imaging method (optical flow) was validated against indirect calorimetry for the estimation of energy expenditure during human walking and running. METHODS Fourteen endurance-trained subjects completed a discontinuous incremental exercise test on a treadmill. Subjects performed 4-min intervals at 3, 5, and 7 km·h (walking) and at 8, 10, 12, 14, 16, and 18 km·h (running) with 30 s of rest between intervals. Heart rate, gas exchange, and mean accelerations of ankle, thigh, wrist, and hip were measured throughout the exercise test. A thermal camera (30 frames per second) was used to quantify optical flow, calculated as the movements of the limbs relative to the trunk (internal mechanical work) and vertical movement of the trunk (external vertical mechanical work). RESULTS Heart rate, gross oxygen uptake (mL·kg·min) together with gross and net energy expenditure (J·kg·min) rose with increasing treadmill velocities, as did optical flow measurements and mean accelerations (g) of ankle, thigh, wrist, and hip. Oxygen uptake was linearly correlated with optical flow across all exercise intensities (R = 0.96, P < 0.0001; V˙O2 [mL·kg·min] = 7.35 + 9.85 × optical flow [arbitrary units]). Only 3-4 s of camera recording was required to estimate an optical flow value at each velocity. CONCLUSIONS Optical flow measurements provide an accurate estimation of energy expenditure during horizontal walking and running. The technique offers a novel experimental method of estimating energy expenditure during human locomotion, without use of interfering equipment attached to the subject.

Automatic Analysis of Activities in Sports Arenas Using Thermal Cameras

The demand for automatically gathered data is a societal trend quickly extending to all aspects of human life. Knowledge on the utilization of public facilities is of interest for optimising use and cutting expenses for the owners. Manual observations are both cumbersome and expensive, and they have a risk of incorrect results due to subjective opinions or lack of interest in the given task. In this paper we present the main results of a 5-year long research project revolving around the real-world application of automatic analysis of activities in sports arenas. Three topics are explored: Counting people, recognising activities, and estimating energy expenditure. The project is based on thermal image data, to preserve privacy while capturing video in public sports arenas. This paper aim to provide an overview of our published methods and results within these three topics and add a discussion of the results and perspectives of this research.

Comparison of two indirect calorimetry devices at varying levels of inspired oxygen

Introduction In addition to systemic hemodynamics, the management of neurocritically ill patients is often informed by neuromonitoring. In the absence of high-level evidence clinicians are often guided by personal and local expertise. Little is known about practices as they pertain to the use of such monitoring in patients with acute brain injury (ABI). Objectives To investigate practices in bedside monitoring for ABI patients. Particularly interested in differences among “neurointensivists” (NIs; defined here as intensivists whose clinical practice is comprised > 1/3 by neurocritical care) and other intensivists (OIs). Also, to explore patterns specific to traumatic brain injury (TBI) and subarachnoid hemorrhage (SAH), as well as preferences and availability of particular technologies/devices. Methods Electronic survey of 22 items including two case-based scenarios; endorsed by SCCM (9,000 recipients) and ESICM (on-line newsletter) in 2013. A sample size of 370 was calculated based on a population of 10,000 physician members, a 5 % margin error, and 95 % confidence interval. We summarized results using descriptive statistics (proportions with 95 % confidence intervals). A chi-square test was used to compare proportions of responses between NIs and OIs with a significance p < 0.05. Results There were 655 responders (66 % completion rate); 422(65 %) were classified as OIs and 226(35 %) as NIs. More NIs follow hemodynamic protocols for neurocritically-ill patients (56 % vs. 43 %, p 0.001), in TBI (44.5 % vs. 33.3 %, p 0.007), and in SAH (38.1 % vs. 21.3 %, p < 000.1). For delayed cerebral ischemia (DCI), more NIs target cardiac index (CI) (35 % vs. 21 %, p 0.0001), and fluid responsiveness (62 % vs. 53 %, p 0.03), use more bedside ultrasound (BUS) (42 % vs. 29 %, p 0.005) and arterial waveform analysis (40 % vs. 29 %, p 0.02). For DCI neuromonitoring, NIs use more angiography (57 % vs. 43 %, p 0.004), TCD (46 % vs. 38 %, p 0.0001), and CTP (32 % vs.16 %, p 0.0001). For CPP optimization in TBI, NIs use more arterial waveform analysis (45 % vs. 35 %, p 0.019), and BUS (37 % vs. 27.7 %, p 0.023), while more OIs monitor mixed venous oxygen saturation (54.1 % vs. 45 %, p 0.045). For TBI neuromonitoring, NIs use more PbtO2 (28 % vs. 10 %, p 0.0001). In the case scenario of raised ICP/low PbtO2, most employ analgosedation (47 %) and osmotherapy (38 %). Fewer make use of preserved pressure reactivity, particularly OIs (vasopressor use 23 % vs. 34 %, p 0.014). Conclusions There is large heterogeneity in the use of monitoring protocols, variables, and technologies/devices. “Neurointensivists” not only employ more neuromonitoring but also more hemodynamic monitoring in patients with acute brain injury. ICP/CPP remain the most commonly followed neuro-variables in TBI patients, with low use of other brain-physiology parameters, sugg

The effect of metabolic acidosis on maximal force production and muscle recruitment during repeated, submaximal calf contractions to task failure (705.11)

GABA and its synthesising enzyme, glutamate decarboxylase, have been detected in the rat kidney [1–2]. GABA has also been found in human plasma and urine [3–4] and most recently, a renoprotective role for GABA has been suggested [5]. We are systematically investigating functional roles for GABA and glutamate in the mammalian kidney. Contractile pericytes regulate vasa recta diameter in response to a number of endogenous vasoactive agents and in doing so regulate medullary blood flow (MBF) [6]. We have utilised the live kidney slice model [6] to demonstrate GABA-mediated constriction of vasa recta that was significantly greater at pericyte sites than at non-pericyte sites (p< 0.01). Conversely, the GABA substrate glutamate (100 ?M) caused a significantly greater vasodilation of vasa recta at pericyte sites compared to non-pericyte sites (p< 0.05). Data presented here identifies a novel role for GABA and glutamate in pericyte-mediated regulation of vasa recta diameter and thus MBF.Obesity frequently associates with chronic inflammatory diseases, including type 2 diabetes. In this study, a combination of a protein hydrolysate, LCPUFAs and a probiotic strain was investigated on the development of high fat diet -induced diabetic risk factors and complications in LDLr-/-.Leiden mice. Male LDLr-/-.Leiden mice at 12 wks of age received a high fat diet (HFD) for 21 wks with or without a combination of an extensive casein hydrolysate, docosahexaenoic acid (DHA), arachidonic acid (ARA), and Lactobacillus Rhamnosus GG (LGG). Both HFD and intervention diet were isocaloric and casein from HFD was replaced with casein hydrolysate in the test diets. The addition of DHA/ARA in the test diets was controlled for in the HFD. Moreover, a PBS gavage control group was included to control for potential effects of LGG gavage. There were significant beneficial effects of the hydrolysate/ARA/DHA/LGG composition versus the HFD control group including reduced body weight gain, lower plasma levels of insulin, cholesterol and triglycerides, lower systemic inflammation, improved adipose tissue quality and mass, and improved kidney and liver function. In a follow up study, evaluating the individual components of the test formulation, some of the outcomes were attributable to the hydrolysate or LGG. A combination of an extensive casein hydrolysate, ARA, DHA and LGG reduces the detrimental effects of HFD on the development of obesity and its metabolic complications. Main risk factors for the metabolic syndrome such as adipose tissue and chronic inflammation were markedly reduced which could provide a rationale for the beneficial effects observed.OBJECTIVETo evaluate the impact of a mobile phone SMS text message intervention on the exclusiveness of breastfeeding (EBF) in infants 0–6 months. METHODSA two-arm parallel randomized controlled tr...

Electrical activity of the diaphragm in trained subjects during progressive cycling to exhaustion trials

BACKGROUND: Poor lower limb stability during dynamic movement is thought to increase the risk of musculoskeletal injury. Biomechanically, stability is determined by a number of factors including the external load and contributions from passive and active tissues. One approach for studying lower limb stability is the single leg squat (SLS) test, which requires coordinated lower limb movement across a range of joint motions under external load. Although clinicians typically assess SLS quality from a single point of view (i.e. frontal plane), a 3D investigation of SLS kinematics would help to determine factors that differentiate clinician-defined “good” from “poor” quality performance. PURPOSE: To determine the kinematic parameters that characterise a good or a poor SLS performance in young adults. METHODS: 22 healthy young adults (13 male, 9 female; age: 23.8 ±3.1 years; height: 1.73 ±0.07 m; mass: 69.4 ±12.7 kg) free from musculoskeletal impairment were recruited. Video footage was collected in the frontal plane as participants performed three SLSs on each leg. SLS quality was assessed by a panel of physiotherapists using a ten-point ordinal scale. Performances were subsequently divided into tertiles corresponding to poor, intermediate and good SLS technique. 3D trajectories of 28 reflective markers attached to the pelvis, and lower limbs were simultaneously recorded at 200 Hz using a 10-camera, motion capture system (Vicon Motion Systems, Oxford, UK). Pelvis, hip and knee angles were calculated using a validated lower limb biomechanical model that incorporated functional identification of hip and knee joint centres. RESULTS: Mean rating of SLS quality as assessed by the panel of physiotherapists was 6.3±1.9 (range: 2.4 - 9.1). 3D analysis of SLS performance revealed that poor squatters had increased hip adduction (22.4 ±6.1 vs 14.7 ±4.7 deg, p<0.01), reduced knee flexion (73.1 ±8.7 vs 90.1 ±12.1 deg, p<0.01) and increased medal-lateral displacement of the knee joint centre (53.7 ±16.8 vs 38.4 ±14.3 mm, p=0.02) compared to good squatters. CONCLUSION: In healthy young adults a poor SLS is characterised by inadequate knee flexion and excessive frontal plane motion at the knee and hip. It is recommended that clinicians standardise knee flexion angle when using the SLS test as it might confound the perception of SLS quality.Purpose: To evaluate changes in performance and cardiac autonomic control (i.e. heart rate [HR] variability [HRV]) in elite soccer players during their pre-season training regime. Methods: Eight Spanish Premier League soccer players were examined at the first (week 1) and the last week (week 8) of the pre-season period (July-September). Nocturnal HR recordings on 4 days per week were averaged to evaluate the weekly HRV. Players also completed the Yo-Yo intermittent recovery test level 1 (Yo-Yo IR1) for the assessment of specific fitness. Results: During the pre-season period, there was no significant change (4.5 ± 23.9%) in Yo-Yo IR1 performance (2,475 ± 421 vs. 2,600 ± 786 m, p=0.55), while there was a significant decrement (6.3 ± 4.3%) in maximal HR (HRmax) recorded during the test (191 ± 7 vs. 179 ± 8 bpm, p = 0.004). Over the 8-week pre-season, significant increases in the standard deviation of the long-term continuous HRV (SD2) (174 ± 56 vs. 212 ± 53 ms, p = 0.017), and in the standard deviation of all HR intervals (SDNN) (135 ± 50 vs. 163 ± 41 ms, p = 0.023) were noted. No significant correlations were identified between Yo-Yo IR1 and HRV measures at week 1. In contrast, Yo-Yo IR1 performance was significantly correlated with SDNN (r =0.89, p=0.007) and SD2 (0.92, p=0.003) at week 8. Greater values in HRV at week 1 were substantially associated with lower HRV changes at the end of pre-season (r values ranged from -0.79 to -0.98, p< 0.05). Furthermore, HRV changes were significantly correlated with decreases in HRmax during the pre-season (r values from 0.83 to 0.94, p<0.05). Conclusions: The current results confirm that despite minimal changes in specific fitness (i.e. Yo-Yo IR1), pre-season training significantly improved various HRV indices in elite soccer players with greater changes evident for those with lower initial HRV levels. Nocturnal HRV may provide an important monitoring tool for identification of cardiovascular function changes in top-class soccer players during pre-season regimes.