Reduced inclination of cervical spine in a novel notebook screen system : implications for rehabilitation

Background: Professional working at computer notebooks is associated with high requirements on the body posture in the seated position. By the high continuous static muscle stress resulting from this position at notebooks, professionals frequently working at notebooks for long hours are exposed to an increased risk of musculoskeletal complaints. Especially in subjects with back pain, new notebooks should be evaluated with a focus on rehabilitative issues. Methods: In a field study a new notebook design with adjustable screen was analyzed and compared to standard notebook position. Results: There are highly significant differences in the visual axis of individuals who are seated in the novel notebook position in comparison to the standard position. Also, differences are present between further alternative notebook positions. Testing of gender and glasses did not reveal influences. Conclusion: This study demonstrates that notebooks with adjustable screen may be used to improve the posture. Future studies may focus on patients with musculoskeletal diseases

Power output, cadence, and torque are similar between the forward standing and traditional sprint cycling positions

Purpose: Compare power output, cadence, and torque in the seated, standing, and forward standing cycling sprint positions. Methods: On three separated occasions (ie, one for each position), 11 recreational male road cyclists performed a 14 seconds sprint before and directly after a high-intensity lead-up. Power output, cadence, and torque were measured during each sprint. Results: No significant differences in peak and mean power output were observed between the forward standing (1125.5 ± 48.5 W and 896.0 ± 32.7 W, respectively) and either the seated or standing positions (1042.5 ± 46.8 W and 856.5 ± 29.4 W; 1175.4 ± 44.9 W and 927.5 ± 28.9 W, respectively). Power output was higher in the standing, compared with the seated position. No difference was observed in cadence between positions. At the start of the sprint before the lead-up, peak torque was higher in the standing position vs the forward standing position; and peak torque occurred later in the pedal revolution for both the forward standing and standing positions when compared with the seated position. At the start of the sprint after the lead-up, peak torque occurred later in the forward standing position when compared with both the seated and standing position. At the end of the sprint, no difference in torque was found between the forward standing and standing position either before or after the lead-up. Conclusion: Sprinting in the forward standing sprint position does not impair power output, cadence, and torque when compared with the seated and standing sprint positions

Estimates of persistent inward current in human motor neurons during postural sway

Persistent inward current (PIC) is a membrane property critical for increasing gain of motor neuron output. In humans, most estimates of PIC are made from plantarflexor or dorsiflexor motor units with the participant in a seated position with the knee flexed. This seated and static posture neglects the task-dependent nature of the monoaminergic drive that modulates PIC activation. Seated estimates may drastically underestimate the amount of PIC that occurs in human motor neurons during functional movement. The current study estimated PIC using the conventional paired motor unit technique which uses the difference between reference unit firing frequency at test unit recruitment and reference unit firing frequency at test unit de-recruitment (∆F) during triangular-shaped, isometric ramps in plantarflexion force as an estimate of PIC. Estimates of PIC were also made during standing anterior postural sway, a postural task that elicits a ramped increase and decrease in soleus motor unit activation similar to the conventional seated ramp contractions. For each motor unit pair, ∆F estimates of PIC made during conventional isometric ramps in the seated posture were compared to those made during standing postural sway. Baseline reciprocal inhibition (RI) was also measured in each posture using the post-stimulus time histogram (PSTH) technique. Hyperpolarizing input has been shown to have a reciprocal relationship with PIC in seated posture and RI was measured to examine if the same reciprocal relationship holds true during functional PIC estimation. It was hypothesized that an increase in ∆F would be seen during standing compared to sitting due to greater neuromodulatory input. We found that ∆F estimates during standing postural sway were equal (2.44 ± 1.17, p=0.44) to those in seated PIC estimates (2.73± 1.20) using the same motor unit pair. Reciprocal inhibition was significantly lower when measured in a standing posture (0.0031 ± 0.0251,

Reducing aerodynamic drag by adopting a novel road-cycling sprint position

Purpose: To assess the influence of seated, standing, and forward-standing cycling sprint positions on aerodynamic drag (CdA) and the reproducibility of a field test of CdA calculated in these different positions. Methods: A total of 11 recreational male road cyclists rode 250 m in 2 directions at around 25, 32, and 40 km·h. Results: A main effect of position showed that the average CdA of the 2 d was lower for the forward-standing position (0.295 [0.059]) compared with both the seated (0.363 [0.071], P = .018) and standing positions (0.372 [0.077], P = .037). Seated and standing positions did not differ from each other. Although no significant difference was observed in CdA between the 2 test days, a poor between-days reliability was observed. Conclusion: A novel forward-standing cycling sprint position resulted in 23% and 26% reductions in CdA compared with a seated and standing position, respectively. This decrease in CdA could potentially result in an important increase in cycling sprint velocity of 3.9-4.9 km·

Validity and reliability of lower-limb pulse-wave velocity assessments using an oscillometric technique

There is a growing interest in the deleterious effects of sedentary behaviour on lower-limb arterial health. To permit further investigation, including in larger epidemiological studies, there is a need to identify lower-limb arterial health assessment tools that are valid and reliable, yet simple to administer. Purpose: This study sought to determine the validity and between-day reliability of femoral-ankle pulse-wave velocity (faPWV) measures obtained using an oscillometric-based device (SphygmocCor XCEL) in supine and seated positions. Doppler ultrasound (US) was used as the criterion. Methods: A total of 47 healthy adults were recruited for validity (n=32) and reliability (n=15) analyses. Validity was determined by measuring faPWV in seated and supine positions using the XCEL and US devices, in a randomised order. Between-day reliability was determined by measuring seated and supine faPWV using the XCEL on 3 different mornings, separated by a maximum of 7 days. Results: The validity criteria (absolute standard error of estimate [aSEE] <1.0 m/s) was met in the supine (aSEE = 0.8 m/s, 95% CI: 0.4-1.0), but not the seated (aSEE = 1.2 m/s, 95 % CI: 1.1, 1.2) position. Intras-class correlation coefficient estimates revealed the XCEL demonstrated good reliability in the supine position (ICC=0.83, 95% CI: 0.65, 0.93), but poor reliability in the seated position (ICC = 0.29, 95% CI: 0.23, 0.63). Conclusions: The oscillometric XCEL device can be used to determine lower-limb PWV with acceptable validity and reliability in the conventionally recommended supine position, but not the seated position

The Physiologic and Behavioral Implications of Playing Active and Sedentary Video Games in a Seated and Standing Position

International Journal of Exercise Science 7(3) : 194-201, 2014. Previous studies have assessed physiologic response while playing video games per manufacturer instructions with participants standing during active video game play and seated during sedentary game play. It is not known whether an assigned seated or standing position affects positional preference and oxygen consumption (VO2) while gaming. The purpose of the study was to assess VO2 and preference of playing active and sedentary video games in a seated and standing position. VO2 was assessed in 25 participants during four, 20-minute conditions; resting, PlayStation 2 Madden NFL Football 2011, Nintendo Wii-Sports Boxing and Nintendo Wii Madden NFL Football 2011. Each condition was divided into two positional conditions (10 minutes seated, 10 minutes standing) and each participant indicated their positional preference after each 20-minute condition. Standing VO2 (4.4 ± 0.2 ml•kg-1•min-1 PS2, 4.6 ± 0.1 ml•kg-1•min-1 Wii Madden, 6.8 ± 0.3 ml•kg-1•min-1Wii Boxing) was significantly (p ≤ 0.001) greater than seated VO2 (4.0 ± 0.1 ml•kg-1•min-1 PS2, 4.2 ± 0.1 ml•kg-1•min-1 Wii Madden, 6.1 ± 0.3 ml•kg-1•min-1Wii Boxing) for each gaming condition. Participants preferred (p ≤ 0.001) to sit for all gaming conditions except Wii Boxing. Playing video games while standing increases VO2 to a greater extent than playing the same games in a seated position. Standing was only preferred for the most physiologically challenging game, Wii Boxing. Gaming position should be considered when assessing the physiologic and behavioral outcomes of playing video games

The iconographic transformation of the “tail of the dragon of the eclipse” into the “hunting cheetah”

Medieval Islamic iconography includes many depictions in which the tail of Sagittarius takes the form of the “dragon of the eclipse”. The current paper examines the gradual transformation of this imagery into that of a quadruped, eventually detached from the body of Sagittarius, and placed on the centaur’s back in the characteristic position of the seated “hunting cheetah”, as can also be seen in images of the chase assisted by this feline

Influence and reliability of lower-limb arterial occlusion pressure at different body positions

Background: Total arterial occlusive pressure (AOP) is used to prescribe pressures for surgery, blood flow restriction (BFRE) and ischemic preconditioning (IPC). AOP is often measured in a supine position; however, the influence of body position on AOP measurement is unknown and may influence of the level of occlusion in different positions during BFR and IPC. The aim of this study was therefore to investigate the influence of body position on AOP. Methods: Fifty healthy individuals (age = 29 ± 6 y) underwent AOP measurements on the dominant lower-limb in supine, seated and standing positions in a randomised order. AOP was measured automatically using an automated pneumatic tourniquet system, with each measurement separated by 5 minutes of rest. Results: AOP was significantly lower in the supine position compared to the seated position (187.00 ± 32.5 vs 204.00 ± 28.5 mmHg, p<0.001) and standing position (187.00 ± 32.5 vs. 241.50 ± 49.3 mmHg, p<0.001). AOP was significantly higher in the standing position compared to the seated position (241.50 ± 49.3 vs. 204.00 ± 28.5 mmHg, p<0.001). Discussion: AOP measurement is body position dependent, thus for accurate prescription of occlusion pressure during surgery, BFR and IPC, AOP should be measured in the position intended for subsequent application of occlusion

The Szigliget maar/diatreme, Bakony- Balaton Highland Volcanic Field (Hungary)

A preliminary volcanological mapping has been carried out in the western part of the Bakony- Balaton Highland Volcanic Field (BBHVF) around Szigliget (Hungary) village. Pyroclastic rocks have been found building up the three distinct hillsides in the area. The pyroclastic rock beds in each hillside show similar north-westward dip direction and similar textural and compositional characteristics, suggestive of a complex but closely related volcanic system in the area. The pyroclastic deposits have been grouped into three units according to their textural, compositional and stratigraphic characteristics. Unit 1 which represents the lowermost stratigraphic position crops out in the southern side of the study area. It consists of coarse-grained, matrix-supported massive to weakly bedded, accidental lithic clast-rich, block-bearing lapilli tuffs / tuff breccias, extremely rich in deep-seated accidental lithic and peridotite lherzolite clasts. Unit 2 which represents an intermediate stratigraphic position crops out in the southern and north-east hilltops. It consists of coarse-grained accidental lithic clast-rich, normal graded, bedded, vitric lapilli tuffs / tuff beds. Deep-seated accidental lithic clasts are common, but large peridotite lherzolite fragments are relatively rare. Unit 3 which represents the highest stratigraphic position in the area crops out in the northwestern side. It consists of fine-to-coarse grained, bedded, accidental lithic clast-rich vitric lapilli tuff / tuff beds. Deep-seated lithic clasts as well as peridotite lherzolite fragments are rare. Accidental lithic clasts, derived from shallow prevolcanic strata (Neogene sediments), have a dominant proportion of pyroclastic rocks in this unit. In each unit the volcanic glasses are angular, non- to highly vesiculated tephrite to phono-tephrite shards. The presence of sideromelane glass shards and the large amount of accidental lithic clasts in beds from each units indicate subsurface phreatomagmatic explosive processes during formation of pyroclastic rocks at Szigliget. The pyroclastic rocks are interpreted as part of a former crater rim deposits around maar basin which subsequently subsided inward into a vent. Unit 1 is interpreted to be a lower diatreme deposit and Unit 2 and Unit 3 a series of near-vent pyroclastic density currents and fallout tephra

The effect of posture on asynchronous chest wall movement in COPD.

none6Chronic obstructive pulmonary disease (COPD) patients often show asynchronous movement of the lower rib cage during spontaneous quiet breathing and exercise. We speculated that varying body position from seated to supine would influence rib cage asynchrony by changing the configuration of the respiratory muscles. Twenty-three severe COPD patients (forced expiratory volume in 1 s = 32.5 ± 7.0\% predicted) and 12 healthy age-matched controls were studied. Measurements of the phase shift between upper and lower rib cage and between upper rib cage and abdomen were performed with opto-electronic plethysmography during quiet breathing in the seated and supine position. Changes in diaphragm zone of apposition were measured by ultrasounds. Control subjects showed no compartmental asynchronous movement, whether seated or supine. In 13 COPD patients, rib cage asynchrony was noticed in the seated posture. This asynchrony disappeared in the supine posture. In COPD, upper rib cage and abdomen were synchronous when seated, but a strong asynchrony was found in supine. The relationships between changes in diaphragm zone of apposition and volume variations of chest wall compartments supported these findings. Rib cage paradox was noticed in approximately one-half of the COPD patients while seated, but was not related to impaired diaphragm motion. In the supine posture, the rib cage paradox disappeared, suggesting that, in this posture, diaphragm mechanics improves. In conclusion, changing body position induces important differences in the chest wall behavior in COPD patients.R. Priori;A. Aliverti;A. L. Albuquerque;M. Quaranta;P. Albert;P. M. APriori, Rita; Aliverti, Andrea; A. L., Albuquerque; Quaranta, Marco; P., Albert; P. M., A