| 1. |
- Svensson, A., et al.
(författare)
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A 60 000 year Greenland stratigraphic ice core chronology
- 2008
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Ingår i: Climate of the Past. - : Copernicus GmbH. - 1814-9332. ; 4:1, s. 47-57
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Tidskriftsartikel (refereegranskat)abstract
- The Greenland Ice Core Chronology 2005 (GICC05) is a time scale based on annual layer counting of high-resolution records from Greenland ice cores. Whereas the Holocene part of the time scale is based on various records from the DYE-3, the GRIP, and the NorthGRIP ice cores, the glacial part is solely based on NorthGRIP records. Here we present an 18 ka extension of the time scale such that GICC05 continuously covers the past 60 ka. The new section of the time scale places the onset of Greenland Interstadial 12 (GI-12) at 46.9 +/- 1.0 ka b2k (before year AD 2000), the North Atlantic Ash Zone II layer in GI-15 at 55.4 +/- 1.2 ka b2k, and the onset of GI-17 at 59.4 +/- 1.3 ka b2k. The error estimates are derived from the accumulated number of uncertain annual layers. In the 40-60 ka interval, the new time scale has a discrepancy with the Meese-Sowers GISP2 time scale of up to 2.4 ka. Assuming that the Greenland climatic events are synchronous with those seen in the Chinese Hulu Cave speleothem record, GICC05 compares well to the time scale of that record with absolute age differences of less than 800 years throughout the 60 ka period. The new time scale is generally in close agreement with other independently dated records and reference horizons, such as the Laschamp geomagnetic excursion, the French Villars Cave and the Austrian Kleegruben Cave speleothem records, suggesting high accuracy of both event durations and absolute age estimates.
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| 2. |
- Vinther, Anders, et al.
(författare)
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Exercise-induced rib stress fractures: influence of reduced bone mineral density
- 2005
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Ingår i: Scandinavian Journal of Medicine & Science in Sports. - : Wiley. - 1600-0838 .- 0905-7188. ; 15:2, s. 95-99
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Tidskriftsartikel (refereegranskat)abstract
- Exercise-induced rib stress fractures have been reported frequently in elite rowers during the past decade. The etiology of rib stress fractures is unclear, but low bone mineral density (BMD) has been suggested to be a potential risk factor for stress fractures in weight-bearing bones. The present study investigated BMD in seven Danish national team rowers with previous rib stress fracture (RSF) and 7 controls (C) matched for gender, age, height, weight and training experience. Total body scan and specific scans of the lumbar spine (L2-L4), femoral neck and distal radius were performed using a DEXA scanner. The RSF subjects showed significantly lower L2-L4 BMD: RSF: 1.22 +/- 0.05 g cm(-2) (mean +/- SEM) (median 1.19 g cm(-2), range 1.02-1.37 g cm(-2)) compared to C: 140 +/- 0.04 g cm(-2) (median 1.41 g cm(-2), range 1.27-1.57 g cm(-2)) (P=0.028).The present results suggest that low bone mineral density may be a potential risk factor for the development of exercise-induced rib stress fractures in elite rowers.
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| 3. |
- Vinther, A, et al.
(författare)
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Exercise-induced rib stress fractures: potential risk factors related to thoracic muscle co-contraction and movement pattern
- 2006
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Ingår i: Scandinavian Journal of Medicine & Science in Sports. - : Wiley. - 1600-0838 .- 0905-7188. ; 16:3, s. 188-196
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Tidskriftsartikel (refereegranskat)abstract
- The etiology of exercise-induced rib stress fractures (RSFs) in elite rowers is unclear. The purpose of the study was to investigate thoracic muscle activity, movement patterns and muscle strength in elite rowers. Electromyographic (EMG) and 2-D video analysis were performed during ergometer rowing, and isokinetic muscle strength was measured in seven national team rowers with a history of RSF and seven matched controls (C). RSF displayed a higher velocity of the seat in the initial drive phase (RSF: 0.25 +/- 0.03, 0.25 (0.15-0.33) m/s vs C: 0.15 +/- 0.06, 0.18 (-0.11-0.29) m/s P = 0.028) (Mean +/- SEM, median and range). Further, RSF had greater co-contraction of m. serratus anterior and m. trapezius in the mid-drive phase (RSF: 47.5 +/- 3.4, 48.5 (35.8-60.2)% EMG signal overlap vs C: 30.8 +/- 6.5, 27.0 (11.2-61.6)% P = 0.043). In addition, the RSF subjects showed a lower knee-extension to elbow-flexion strength ratio (RSF: 4.2 +/- 0.22, 4.3 (3.5-5.1) vs C: 4.8 +/- 0.16, 5.0 (4.2-5.3) P = 0.043), indicating stronger arms relative to legs compared with controls. In conclusion, increased thoracic muscle co-contraction, altered movement patterns and reduced leg/arm strength ratio were observed in the RSF subjects, which may all predispose toward an increased risk of RSF.
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