Hypobaric versus normobaric hypoxia: same effects on postural stability?

AIMS: To test the hypothesis that postural stability would be more affected during acute exposure in hypobaric (HH) than in normobaric (NH) hypoxia.¦METHODS: In separate trials, 12 subjects stood on a posturographic platform for two successive 25.6 sec tests in three conditions: eyes open (EO), eyes closed (EC), and verbal dual task (DT). Ambient pressure in O(2) was matched between HH and NH at 1700 and 3000 m, respectively.¦RESULTS: Compared to NH, the length of Centre of Pression trajectory in Y-axis was increased (p<0.05) in HH for EO at 1700 m, EC at 1700 and 3000 m, and for DT at 1700 m, whereas the variance of speed of CoP was decreased (p<0.05) in EO, EC, and DT at 1700 m. Compared to normobaric normoxia (NN; 400 m), the surface of CoP trajectory was increased (p<0.05) in HH in EO and EC at 3000 m.¦CONCLUSIONS: HH deteriorated postural stability in the antero-posterior plane, for the variance of speed and the surface of CoP in 3 conditions, whereas no difference was observed between NH and NN. These results suggest that hypobaria instead of hypoxia per se plays an important role to the altered balance classically reported in altitude.

Uuden dramaturgian pirstaloitunut kokonaisuus : mitä ja miten ilmaisen

Opinnäyte tutkii mitä tapahtuu kun ajan, paikan ja tapahtuman ykseys poistuu ja astutaan niin sanotun uuden teatterin maailmaan. Miten esityksen kokonaisuus muodostetaan silloin? Opinnäytteessä käytetään pohjamateriaalina kahta liki sanatonta esitystä (nimetön esitys ja Jälkikirjoitus köyhyyden filosofiaan) ja teatteri-ohjaaja/teoreetikko Juha-Pekka Hotisen ja avantgarde-taiteilija/teoreettikko Marcel Duchampin ajatuksia taiteesta (sen rajoista ja katsojista), sekä kirjoittajan omia käsitteitä. Opinnäyte esittelee perhedramaturgia-käsitteen, joka kokoaa avoimen fragmentaarisen dramaturgian erottamalla mitä ja miten esitys ilmaisee. Perhedramaturgiaan kuuluu kaksi ns. ulompaa kehää (käsitettä): assosiatiivisuus ja aika. Opinnäytteessä selitetään perhedramaturgian, assosiatiivisuuden ja ajan suhde toisiinsa ja se miten ne ilmenevät teatterissa. Opinnäytteessä käsitellään myös miten avoin dramaturgia on muuttanut esityksen ja teoksen eroa, rajaa eri taidemuotojen välillä ja miten katsojasuhde on muuttunut. Näitä tutkitaan Hotisen ja Duchampin käsityksiä vasten. Opinnäyte loppuu kuuteen esimerkkiin yrityksestä ilmaista aikaa taideteoksessa.

Alterations in Postural Control during the World's Most Challenging Mountain Ultra-Marathon

We investigated postural control (PC) effects of a mountain ultra-marathon (MUM): a 330-km trail run with 24000 m of positive and negative change in elevation. PC was assessed prior to (PRE), during (MID) and after (POST) the MUM in experienced ultra-marathon runners (n = 18; finish time = 126+/-16 h) and in a control group (n = 8) with a similar level of sleep deprivation. Subjects were instructed to stand upright on a posturographic platform over a period of 51.2 seconds using a double-leg stance under two test conditions: eyes open (EO) and eyes closed (EC). Traditional measures of postural stability (center of pressure trajectory analysis) and stabilogram-diffusion analysis (SDA) parameters were analysed. For the SDA, a significantly greater short-term effective diffusion was found at POST compared with PRE in the medio-lateral (ML; Dxs) and antero-posterior (AP) directions (Dys) in runners (p<0.05) The critical time interval (Ctx) in the ML direction was significantly higher at MID (p<0.001) and POST (p<0.05) than at PRE in runners. At MID (p<0.001) and POST (p<0.05), there was a significant difference between the two groups. The critical displacement (Cdx) in the ML was significantly higher at MID and at POST (p<0.001) compared with PRE for runners. A significant difference in Cdx was observed between groups in EO at MID (p<0.05) and POST (p<0.005) in the ML direction and in EC at POST in the ML and AP directions (p<0.05). Our findings revealed significant effects of fatigue on PC in runners, including, a significant increase in Ctx (critical time in ML plan) in EO and EC conditions. Thus, runners take longer to stabilise their body at POST than at MID. It is likely that the mountainous characteristics of MUM (unstable ground, primarily uphill/downhill running, and altitude) increase this fatigue, leading to difficulty in maintaining balance.