Energy expended playing Xbox Kinect™ and Wii™ games: a preliminary study comparing single and multiplayer modes.

OBJECTIVES: It has been reported that a higher galvanic skin response is seen when playing video games against another human player than when playing alone, which suggests increased effort. The objectives of this study were to compare energy expenditure when playing two popular active video game consoles, and to compare energy expenditure when playing in single and multiplayer modes. DESIGN: Crossover trial with randomised playing order. PARTICIPANTS: Fourteen healthy adults with a mean age of 21 [standard deviation (SD) 3] years. METHODS AND INTERVENTIONS: Energy expenditure was measured using an indirect calorimeter at rest, during 10 minutes of play on Xbox Kinect™ Reflex Ridge in both single and multiplayer modes, and during 10 minutes of play on Wii™ Sports Boxing in both single and multiplayer modes. MAIN OUTCOME MEASURES: Metabolic equivalents (METs), heart rate, oxygen consumption and kilocalories expended. RESULTS: The energy expenditure during all gaming conditions was of a light intensity. Playing on the Xbox Kinect elicited greater energy expenditure than playing on the Wii [mean difference=0.9 METs, 95% confidence interval (CI) 0.2 to 1.5]. Playing games in multiplayer mode led to greater energy expenditure (mean difference=0.5 METs, 95% CI 0.1 to 0.9) and heart rate (mean difference=7.9 beats/minute, 95% CI 2.0 to 13.8) than playing in single player mode. CONCLUSIONS: No gaming condition required moderate-intensity activity in this group of young healthy adults. Potential explanations for the difference in energy expenditure seen between consoles and modes are discussed.

Mechanisms of exertional dyspnea in patients with cancer.

Exertional dyspnea is an important symptom in cancer patients, and, in many cases, its cause remains unexplained after careful clinical assessment. To determine mechanisms of exertional dyspnea in a variety of cancer types, we evaluated cancer outpatients with clinically important unexplained dyspnea (CD) at rest and during exercise and compared the results with age-, sex-, and cancer stage-matched control cancer (CC) patients and age- and sex-matched healthy control participants (HC). Participants (n = 20/group) were screened to exclude clinical cardiopulmonary disease and then completed dyspnea questionnaires, anthropometric measurements, muscle strength testing, pulmonary function testing, and incremental cardiopulmonary treadmill exercise testing. Dyspnea intensity was greater in the CD group at peak exercise and for a given ventilation and oxygen uptake (P < 0.05). Peak oxygen uptake was reduced in CD compared with HC (P < 0.05), and breathing pattern was more rapid and shallow in CD than in the other groups (P < 0.05). Reduced tidal volume expansion during exercise correlated with reduced inspiratory capacity, which, in turn, correlated with reduced inspiratory muscle strength. Patients with cancer had a relatively reduced diffusing capacity of the lung for carbon monoxide, reduced skeletal muscle strength, and lower ventilatory thresholds during exercise compared with HC (P < 0.05). There were no significant between-group differences in measurements of airway function, pulmonary gas exchange, or cardiovascular function during exercise. In the absence of evidence of airway obstruction or restrictive interstitial lung disease, the shallow breathing pattern suggests ventilatory muscle weakness as one possible explanation for increased dyspnea intensity at a given ventilation in CD patients.

Effects of muscle strengthening and physical conditioning training on temporal, kinematic and kinetic variables during gait in chronic stroke survivors.

The purpose of this study was to evaluate the impact of a combined program of muscle strengthening and physical conditioning on gait performance in subjects with chronic stroke, using a single group pre- and post-test design. Thirteen subjects were recruited for the 10-week program (3 days/week), which consisted of warm-up, aerobic exercises, lower extremity muscle strengthening and cool-down. Data from cinematographic film and a force plate obtained during multiple walking trials were used in a four-segment kinetic model to yield spatiotemporal, kinematic and kinetic variables. Gait analysis revealed that the 10 week training resulted in significant increases in gait speed associated with improvements in walking patterns as determined by increases in selected kinematic and kinetic measures. After training, subjects were able to generate higher levels of powers and demonstrated increases in positive work performed by the ankle plantar flexor and hip flexor/extensor muscles.

Multivariate examination of data from gait analysis of persons with stroke.

BACKGROUND AND PURPOSE: Gait analyses yield redundant information that often is difficult to interpret. The purpose of this study was to show how principal-component analysis can provide insight into gait data obtained from persons with stroke. SUBJECTS: Twenty male and 11 female adults who were ambulatory were studied (mean age = 60.5 years, SD = 11.8, range = 24-79; mean time since stroke = 11.4 months, SD = 15.4, range = 2.0-88.0). METHODS: Spatial data were used in a 4-segment link-segment model to calculate the kinematic and kinetic variables of gait. Principal components were constructed on the averages for 40 variables. RESULTS: The first principal component was related to speed and accounted for 40.8% of the variance. The second principal component was related to differences between the 2 limbs (symmetry) and accounted for 12.8% of the variance. The third principal component was related to adoption of a postural flexion bias and accounted for 10.2% of the variance. The fourth principal component, which was not interpretable, accounted for 6.8% of the variance. CONCLUSION AND DISCUSSION: The principal-component analysis allowed clustering of related variables and simplified the complex picture presented by the large number of variables resulting from gait analysis. Examination of variables closely related to each principal component yielded insight into the nature of the strategies used in walking and their interrelationships. The method has potential for insight into similarities and differences in gait performances arising from different pathologies and for comparing the progress of individuals with similar pathologies.

Temporal, kinematic, and kinetic variables related to gait speed in subjects with hemiplegia: a regression approach.

BACKGROUND AND PURPOSE: The gait speed that a patient selects is a well-known indicator of overall gait performance. The purpose of this study was to use multiple linear regression to assess the strength of association of temporal, kinematic, and kinetic gait variables with high walking speeds in patients with hemiplegia. SUBJECTS: Thirty-two subjects (20 male, 12 female) with an average age of 61 years took part in a sagittal-plane gait study of both sides of the body. METHODS: Data from cinematographic film and a force plate obtained during multiple walking trials were used in a seven-segment link-segment kinetic model of the walking subject to yield temporal, kinematic, and kinetic variables. RESULTS: Variables correlating significantly with self-selected speed included the maximum hip extension angle and the maximum hip flexion moment on the affected side, and the maximum ankle and hip powers on both sides. A stepwise regression identified variables most useful in predicting stride speed. For the affected side, these variables were the hip flexion moment, the ankle moment range, the knee moment range, and the proportion of double support. Together these variables explained 94% of the variation in gait speed. On the unaffected side, the variables were the percentage of stance phase, the maximum ankle power (push-off), and the maximum hip power (pull-off). They explained 92% of the variation in gait speed. CONCLUSION AND DISCUSSION: These results suggest that experimental studies are needed to assess the effects of treatment aimed at increasing ankle power and hip power and at decreasing the stance time on the affected side, and that these studies should be directed at obtaining a larger hip flexion moment and a larger ankle moment range on the unaffected side.

First metatarsophalangeal joint reaction forces during high-heel gait.

First metatarsophalangeal (MTP) joint reaction forces were calculated for 11 normal females during the toe-off phase of gait while walking in bare feet and in high heeled shoes. A biomechanical model was used to calculate the forces utilizing kinematic, kinetic, footprint, and radiographic data. The results showed that the MTP joint reaction forces (FJ), the metatarsal-sesamoid forces (FS), and the resultant of these forces (FRES), were twice as large in high heels compared to barefoot walking. The average peak forces for barefoot and high-heeled gait were FJ: 0.8 and 1.58 times body weight, FS: 0.44 and 1.03 times body weight, and FRES: 0.93 and 1.88 times body weight. Also, the kinematics changed when wearing high heels, making angles of application of forces and sesamoidal articulations less favorable.

Work and power in gait of stroke patients.

Biomechanical analysis of the work and power patterns involved in gait provides insight into the nature of gait deficits and suggests methods for improvement. The purpose of this study was to describe the work and power characteristics during gait for both limbs of hemiplegic patients, and to determine the work and power variables related to self-selected speeds of walking. The gait of 30 ambulatory adults between the ages of 47 and 79 years was studied using two-dimensional cinematography and force-plate data in a link-segment model. About 40% of the positive work required for walking was performed by the muscles of the affected side. Major contributors were the ankle plantar flexors, hip flexors, and hip extensors. The results suggest interdependence between the limbs and between muscle groups of the same limb; a need for further research is indicated.

Joint reaction forces at the first MTP joint in a normal elderly population.

The calculation of net ankle, knee, and hip joint reaction forces is an often applied procedure in the analysis of gait. Except for very few studies, joint reaction forces have not been measured in other joints such as the fingers, wrist, elbow, shoulder and toes. In this study the joint reaction forces between the metatarsal head and the proximal phalanx and the metatarsal head and the sesamoids are calculated for the push off phase during gait. The results of ten normal elderly subjects show that the maximum resultant loads of the two articulations lie close to the longitudinal axis of the metatarsal. The knowledge of the magnitude and direction of the joint reaction forces of a normal elderly population will be essential for the design of an optimal fixation of an artificial anatomical first MTP joint.

Biomechanical considerations of the menisci of the knee.

The menisci of the knee are important structures for maintaining a healthy joint since they absorb shock and prevent rotatory instability. The shapes of the menisci and the orientations of their collagen fibres are naturally suited for bearing weight of the joint. Their shape also allows the tibial plateau contact area to be three times greater, thereby decreasing the stress by up to seven times. The medial and lateral menisci are able to move to different extents as a result of the variable laxities of the adjoining ligaments. Often a meniscus becomes injured and must be surgically removed by either a partial or total meniscectomy. Many meniscal injuries occur during sports activities and are caused predominantly by a twisting motion. A meniscectomy has been shown to have detrimental effects including increased joint laxity, osteoarthritis, and other structural changes. Approximately 25% of those who have had a total meniscectomy must stop or restrict their sports activities.