Matching optical flow to motor speed in virtual reality while running on a treadmill

We investigated how visual and kinaesthetic/efferent information is integrated for speed perception in running. Twelve moderately trained to trained subjects ran on a treadmill at three different speeds (8, 10, 12 km/h) in front of a moving virtual scene. They were asked to match the visual speed of the scene to their running speed–i.e., treadmill’s speed. For each trial, participants indicated whether the scene was moving slower or faster than they were running. Visual speed was adjusted according to their response using a staircase until the Point of Subjective Equality (PSE) was reached, i.e., until visual and running speed were perceived as equivalent. For all three running speeds, participants systematically underestimated the visual speed relative to their actual running speed. Indeed, the speed of the visual scene had to exceed the actual running speed in order to be perceived as equivalent to the treadmill speed. The underestimation of visual speed was speed-dependent, and percentage of underestimation relative to running speed ranged from 15% at 8km/h to 31% at 12km/h. We suggest that this fact should be taken into consideration to improve the design of attractive treadmill-mediated virtual environments enhancing engagement into physical activity for healthier lifestyles and disease prevention and care

Skeletal muscle characteristics and motor performance after 2-year growth hormone treatment in adults with prader-willi syndrome.

Context:In adults with Prader-Willi syndrome (PWS), abnormal body composition with decreased lean body mass and skeletal muscle (SM) volume has been related to altered GH secretion and may possibly contribute to greatly reduced motor capacity.Objective:The scope of the study was to test the hypothesis that GH treatment has favorable effects on SM characteristics and motor performance in adults with PWS.Design, Setting, and Participants:Fifteen obese PWS subjects (nine males and six females; age range, 19–35 y; body mass index, 37.7–59.9 kg/m2) were investigated before and after 12 (GH12) and 24 (GH24) months of GH treatment.Main Outcome Measures:SM cross-sectional area and SM attenuation were determined with computed tomography at the lumbar and midthigh levels. Maximal isometric handgrip strength and isokinetic knee extension peak torque were measured. Motor performance was evaluated with different indoor walking tests, whereas exercise endurance was assessed with a treadmill incremental test to exhaustion.Results:A condition of severe GH deficiency was found in six patients (40%). GH treatment significantly increased lean body mass (GH12, P < .05; GH24, P < .05), reduced percentage of body fat (GH12, P < .05; GH24, P < .05), and augmented SM cross-sectional area and SM attenuation of both lumbar (GH12, P < .01; GH24, P < .001) and thigh muscles (GH24, P < .05). Handgrip strength increased by 7% at GH12 (P < .05) and by 13% at GH24 (P < .001). Peak torque of knee extension extrapolated at zero angular velocity was significantly higher at GH24 (P < .01), and exercise endurance rose by 13% (P < .05) and 17% (P < .05) before exhaustion at GH12 and GH24, respectively, whereas no change was detected with walking tests. No significant difference in the response to GH treatment was detected between patients with and without GH deficiency.Conclusion:Long-term GH treatment in adult PWS patients improves body composition and muscle size and quality and increases muscle strength and exercise tolerance independently from the GH secretory status

Sedentary behaviors and physical activity habits independently affect fat oxidation in fasting conditions and capillary glucose levels after standardized glucose-rich meal in healthy females

Purpose: Sedentary behaviors and muscle inactivity are being growingly recognized as important risk factors for health, adjunctively and independently from a scarce physical activity (PA), although the metabolic mechanism underneath is barely clear. To explore the relation between sedentary behaviors (SBs) and metabolism, we measured the metabolic profile in fasting condition and after oral glucose overload in a group of women, along with objective monitoring of their PA/sedentary lifestyle habits. Subjects and methods: Thirteen women (age: 32.5 ± 16.1 years; BMI: 24.0 ± 3.3 kg/m2), recruited among university students and research staff, underwent indirect calorimetry to assess fat and carbohydrate contribution to energy metabolism, in fasting conditions and after a glucose-rich standard meal (about 45 g of glucose). Glucose concentration in capillary blood was determined in fasting state and 15 and 30 min after meal. Habitual PA and SBs in the previous week were continuously monitored with Actigraph accelerometers. Results: After adjustment for age, the contribution of fat oxidation to metabolic energy sources, normalized for fat-free mass, in fasting conditions was significantly correlated with time spent in sitting/lying position during wake hours (p < 0.001), independent from PA habits, whereas capillary blood peak and change of glucose concentration after the meal were significantly and inversely correlated with average daily moderate to vigorous PA (p = 0.025 and p = 0.019, respectively), independent from average daily sitting/lying time. Conclusions: Here, we report for the first time a direct effect of muscle inactivity on increased fat oxidation in fasting conditions, which can be hypothesized as a preliminary condition for the development of insulin resistance. We also report the direct independent effect of PA on the capacity to respond to a glycemic load, so that SBs and reduced PA appear to concur, although independently, to the increased health risk, as elsewhere observed on an epidemiological ground

Regular physical activity modulates perceived visual speed when running in treadmill-mediated virtual environments

In virtual reality, visual speed is usually underestimated relative to locomotor speed. Here we investigated how physical activity and fitness affect perceived visual speed when running in a treadmill-mediated virtual environment. Thirty healthy participants (ten sedentary individuals, ten team sport players and ten expert runners) ran on a treadmill at two different speeds (8, 12km/h) in front of a moving virtual scene. Participants were asked to match the speed of the visual scene to their running speed (i.e. treadmill speed), indicating for each trial whether the scene was moving slower or faster than the treadmill. The speed of the visual scene was adjusted according to the participant’s response using a staircase until visual and running speeds were perceived as equivalent. More sedentary participants underestimated visual speed relative to their actual running speed. Specifically, visual speed had to exceed running speed to be perceived as equivalent. The underestimation of visual speed was speed- dependent, and it was significantly larger for sedentary participants than for team sports players and expert runners. The volume of physical activity per week was found to be the best predictor of visual speed perception for both running speeds, while the perceived effort constituted a good predictor only at 8km/h. Physical fitness, on the other hand turned out to be a poor predictor of visual speed perception. Therefore, in order to enhance users’ engagement and their adherence to physical activity programs, the development of “personalized” treadmill-mediated virtual environments should take into account users’ personal characteristics to provide the most natural and engaging feedback possible

Promoting healthy teenage behaviour across three European countries through the use of a novel smartphone technology platform, PEGASO fit for future: study protocol of a quasi-experimental, controlled, multi-Centre trial

BackgroundBehaviour change interventions targeting physical activity, diet, sleep and sedentary behaviour of teenagers show promise when delivered through smartphones. However, to date there is no evidence of effectiveness of multicomponent smartphone-based interventions. Utilising a user-centred design approach, we developed a theory-based, multi-dimensional system, PEGASO Fit For Future (PEGASO F4F), which exploits sophisticated game mechanics involving smartphone applications, a smartphone game and activity sensors to motivate teenagers to take an active role in adopting and maintaining a healthy lifestyle. This paper describes the study protocol to assess the feasibility, usability and effectiveness (knowledge/awareness and behavioural change in lifestyle) of the PEGASO system.MethodsWe are conducting a quasi-experimental controlled cluster trial in 4 sites in Spain, Italy, and UK (England, Scotland) over 6 months. We plan to recruit 525, in a 2:1 basis, teenagers aged 13–16 years from secondary schools. The intervention group is provided with the PEGASO system whereas the comparison group continues their usual educational routine. Outcomes include feasibility, acceptance, and usability of the PEGASO system as well as between and within group changes in motivation, self-reported diet, physical activity, sedentary and sleeping behaviour, anthropometric measures and knowledge about a healthy lifestyle.DiscussionPEGASO F4F will provide evidence into the cross-cultural similarities and differences in the feasibility, acceptability and usability of a multi-dimensional smartphone based behaviour change intervention for teenagers. The study will explore facilitating factors, challenges and barriers of engaging teenagers to adapt and maintain a healthy lifestyle when using smartphone technology. Positive results from this ICT based multi component intervention may have significant implications both at clinical level, improving teenagers health and at public health level since it can present an influential tool against the development of chronic disease during adulthood.Trial registrationhttps://clinicaltrials.gov Registration number: NCT02930148, registered 4 October 2016

A mobile phone intervention to improve obesity-related health behaviors of adolescents across Europe: An iterative co-design and feasibility study

Background:Promotion of physical activity, healthy eating, adequate sleep and reduced sedentary behavior in adolescents is a major priority globally given the current increase in population health challenges of non-communicable diseases and risk factors such as obesity. Adolescents are highly engaged with mobile technology, but the challenge is to engage them with mHealth technology. Recent innovations in mobile technology provide opportunities to promote a healthy lifestyle in adolescents. An increasingly utilized approach to facilitate increased engagement with mHealth technology is to involve potential users in the creation of the technology.Objective:To describe the process of and findings from co-designing and prototyping components of the PEGASO Fit for Future mHealth intervention for adolescents from different cultural backgrounds.Methods:Seventy-four adolescents aged 13-16 years from Spain, Italy and the United Kingdom participated in the co-design of the PEGASO Fit for Future technology. In three iterative cycles over 12 months, participants were involved in the co-design, refinement and feasibility testing of a system consisting of diverse mobile applications with a variety of functions and facilities to encourage healthy weight promoting behaviors. In the first iteration, participants attended a single workshop session and were presented with mock-ups or early-version prototypes of different apps for user requirements assessment and review. During the second iteration, prototypes of all apps were tested by participants for one week at home or school. In the third iteration, further developed prototypes were tested for two weeks. Participants’ use experience feedback and development ideas were collected from focus groups and completion of questionnaires.Results:For the PEGASO Fit for Future technology to be motivating and engaging, participants suggested that it should (i) allow personalization of the interface, (ii) have age-appropriate and easy to understand language (of icons, labels, instructions, notifications), (iii) provide easily accessible tutorials on how to use the app or navigate through a game, (iv) present a clear purpose and end goal, (v) have an appealing and self-explanatory reward systems, (vi) offer variation in gamified activities within apps and the serious game, and (vii) allow to seek peer-support and connect with peers for competitive activities within the technology.Conclusions:Incorporating adolescents’ preferences, the PEGASO Fit for Future technology combines the functions of a self-monitoring, entertainment, advisory, and social support tool. This was the first study demonstrating that it is possible to develop a complex smartphone-based technological system applying the principles of co-design to mHealth technology with adolescents across three countries. Findings of this study informed the development of an mHealth system for healthy weight promotion to be tested in a controlled multi-national pilot trial

Influence of body adiposity on structural characteristics of skeletal muscle in men and women

The structure of skeletal muscle (SM) can be characterized by quantitative (size) and qualitative (composition) attributes, which are disparately reported to be influenced by body adiposity. This study tests the hypothesis that body adiposity exerts a systematic influence on these muscle characteristics and evaluates the possible functional implications for movements. Lower limb SM volume (VSM) and attenuation (ATTSM), an inverse measure of lipid infiltration in muscle, were determined with computed tomography in 21 men (BMI = 21-36 kg m-2; age = 31-71 years.) and 18 women (BMI = 19-35 kg m-2; age = 32-76 years.). After adjusting for age, a multivariate regression analysis revealed that body adiposity positively correlated (P<0·05-0·001) with absolute VSM and cross-sectional area (CSA) in both genders, while VSM per unit body mass (VSM/BM) decreased with adiposity (P<0·001) in women and was constant in men. ATTSM was higher in men (P<0·05) and decreased (P<0·05) with adiposity in both genders. The product of ATTSM by average muscle CSA (predictor of maximal strength) and by VSM/BM (predictor of maximal dynamic performance) was lower in women (P<0·001) and was reduced by age in both genders (P<0·05-0·01), while obesity had a negative effect (P<0·001) only on the predictor of performance. In conclusion, body adiposity significantly increases SM size and reduces ATTSM. Structural indicators accounting for both quantitative and qualitative characteristics of SM may be useful predictors of the effects of obesity on motor function at different ages. With rising body adiposity and advancing age, women appear mostly affected by the decline of SM features relevant for motor performance

No evidence that frontal optical flow affects perceived locomotor speed and locomotor biomechanics when running on a treadmill

We investigated how the presentation and the manipulation of an optical flow while running on a treadmill affect perceived locomotor speed (Experiment 1) and gait parameters (Experiment 2). In Experiment 1, 12 healthy participants were instructed to run at an imposed speed and to focus on their sensorimotor sensations to be able to reproduce this running speed later. After a pause, they had to retrieve the reference locomotor speed by manipulating the treadmill speed while being presented with different optical flow conditions, namely no optical flow or a matching/slower/faster optical flow. In Experiment 2, 20 healthy participants ran at a previously self-selected constant speed while being presented with different optical flow conditions (see Experiment 1). The results did not show any effect of the presence and manipulation of the optical flow either on perceived locomotor speed or on the biomechanics of treadmill running. Specifically, the ability to retrieve the reference locomotor speed was similar for all optical flow conditions. Manipulating the speed of the optical flow did not affect the spatiotemporal gait parameters and also failed to affect the treadmill running accommodation process. Nevertheless, the virtual reality conditions affected the heart rate of the participants but without affecting perceived effort