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"Double push is an inline speed skating technique. Its major advantage over the previously practised "classic" technique is that it allows the skater to do useful work during the part of the stride that was "wasted", and therefore to go faster. Opinions differ on its usefulness for non-elite skaters as it requires much practice before a skater is faster using doublepush than without. History It is uncertain who first invented the doublepush. Chad Hedrick is generally acknowledged as having brought it to the public eye. Prior to Chad's arrival on the scene circa 1992, inline speed skaters used the classic speed skating technique derived from ice speed skating. Hedrick's alternative approach rapidly proved itself to be faster and was soon adopted by many elite skaters. Technique Wheels used in speed skating are usually round or elliptical in profile, and do not literally have edges. The terminology is carried over from ice skate blades, which have edges. In inline skating, being "on an inside edge" refers to skating with the wheel of the skate leaning inwards (i.e. medially: right skate leaning left, and vice versa). An outside edge is the opposite, and a center edge implies that the wheel is vertical. The classic speedskating technique is an alternating cycle of inside-edge pushes and outer-edge glides. The cycle starts as the skater is gliding on one (let us suppose the right) leg with a bent knee. Then the right knee straightens (extends) while leaning to the left. The direction of the push is therefore outwards (rightwards) from the center of mass. When the pushing leg reaches full extension, the left (now support) leg is set down and used to glide, while the right leg lifts and is brought back behind and underneath the skater (recovery) ready to be placed on the ground (set down) and become the new support leg. Once the pushing leg has been recovered, the support leg pushes out in the other direction and the cycle repeats. Note that the pushes are always in a lateral direction: the left leg pushes exclusively leftwards, and the right leg exclusively rightwards. This will naturally result in a push that starts on the center edge or on a slight outside edge and "rolls over" onto the inside edge as the foot moves away from the skater's center of mass. The double-push eliminates the "glide" phase from the above cycle, replacing it with a medially-directed "underpush" on the outside-edge. The recovery skate is placed on an outside edge and pushed underneath the body (right leg pushes leftward, and vice versa) while maintaining that outside edge, before being steered or pulled back across the centerline for the regular inside-edge push that follows. By its nature the double-push is less stable than classic technique, making it difficult to learn. If the skater should lose traction during an underpush there is no support leg to fall back on. The double-push also allows for the very brief application of force through both legs simultaneously. The skater does this by transferring weight from the inside-edge foot to the outside-edge foot gradually, rather than transferring all weight to the outside-edge foot instantly. Some hold that this is essential to the double push, but this opinion is not universal. Advantages The principal advantage of the double push is that it allows skaters to generate propulsive force during a part of the stroke cycle which was previously wasted. In the glide phase of the classic stroke, friction from road, atmosphere and bearings tends to slow skaters down, yet the deep knee flexion during this part of the cycle fatigues the muscles. Using DP, skaters can do useful work in this time instead. This is beneficial to their muscles and also helps keep speed more nearly constant instead of surging ahead and then slowing down repeatedly. The DP extends the effective stroke length. One of the best ways to go faster is to push further in each stroke, but whereas traditionally this requires sitting lower (restricting blood flow and increasing lactic acid production in the muscles), in DP the same leg at a higher bend angle can achieve a longer effective stroke by pushing both inward and outwards. Double-Push On Ice Although it is possible to use the double-push in ice skating, it is by no means certain that it can provide the same advantage that it can in inline skating. This has been attributedPublow, Barry (1999). Speed on Skates. Human Kinetics. . to the different characteristics of edging on ice. Whereas an inline skate on a center edge continues to grip the road, an ice blade on a center edge will slip if pushed sideways: it must be on an inside or outside edge if it is to "dig into" the ice. Although some skaters can be seen to be underpushing slightly on ice, the effect is much more subtle. Chad Hedrick, due to his success in connection with the DP, has had his form widely commented on since he moved to ice. The DP has not been widely adopted on ice. Whether this is because it makes little practical difference or for other reasons is at present difficult to say. The main reason why DP does not work on ice, it is proposed, is that ice skates can move only on a straight line or on a big radius, while DP requires carving movements. Perhaps some technical developments could enable creating an ice speed skate that can carve, but it may have more drag. This problem is similar to cross country skis that do not enable carving techniques. References External links *Speed Skating & Double Push For Beginners Category:Speed skating "
"Marcus Cassianius Latinius PostumusJones & Martindale (1971), p. 720 was a Roman commander of Batavian origin who ruled as Emperor in the West. The Roman army in Gaul threw off its allegiance to Gallienus around the year 260,The year of Postumus' accession was either 259 or 260. In the past, the year 259 was favoured; today, however, most scholars consider that the summer or fall of 260 is the more likely date that he was hailed emperor, according to Polfer (Postumus) and J.F. Drinkwater (1987), p. 97. The terminus ante quem is an inscription from September 260 naming Postumus as emperor: Bakker (1993), pp. 369–386. Other dates cited in this article must be pushed back one year for those who take 259 as the year of Postumus' accession. See Drinkwater (1987), pp. 95-106. and Postumus assumed the title and powers of Emperor in the provinces of Gaul, Germania, Britannia and Hispania, thereby founding what scholars have dubbed the Gallic Empire. He ruled for the better part of ten yearsBased on numismatic evidence, Postumus' rule extended over ten periods of tribunician power, each conventionally lasting for one year beginning on December 10. Regardless of which year Postumus assumed the purple (259 or 260), his rule must have stretched across ten such years. See Drinkwater (1987), pp. 93, 95. before he was murdered by his own troops. Life =Rise to power= Little is known about the early life of Postumus. He has been claimed as being of BatavianState, Paul F., A Brief History of the Netherlands, Infobase Publishing, 2008, p. 8 origin; certainly his coinage honors deities — Hercules Magusanus and Hercules Deusoniensis — who would have been popular among the Batavians.Drinkwater (1987), pp. 162-3. Hercules Magusanus was probably an interpretatio romana translation of the Germanic deity Þunraz.Fields, Nic (2006): Roman Auxiliary Cavalryman: AD 14-193, , p. 45-46 Deusoniensis may refer to the town of Deuso, located in or near Batavian territory and likely to be identified with modern-day Diessen; it has been hypothesized that Postumus himself was born in Deuso. From these relatively obscure provincial origins, Postumus would have risen through the ranks of the army until he held command of the Roman forces "among the Celts".The phrase is Zosimus', quoted in Drinkwater (1987), p. 59. What his precise title was is not definitely known,Drinkwater (1987), p. 25. though he may plausibly have been promoted by the emperor Valerian to the position of imperial legate of Germania Inferior.Potter (2004), p. 257 Postumus was evidently in favor at court, and, according to König, was granted an honorary consulship.Drinkwater (1987), p. 67. By 259, Valerian was campaigning in the east against the Persians, while his son and co-emperor Gallienus was preoccupied with the situation on the Danubian frontier.Southern (2001), p. 79 Consequently, Gallienus left his son, Saloninus, and military commanders, including Postumus, to protect the Rhine.Polfer, Postumus Amid the chaos of an invasion by the Alamanni and Franks, and spurred on by news of the defeat and capture of Valerian, the army in Gaul revolted and proclaimed Postumus emperor. The trigger was their defeat in 260 of a Juthungian army which was returning from Italy laden with prisoners, even though they had been repulsed by Gallienus at Mediolanum (Milan).Potter (2004), p. 256 Under the command of Postumus and Marcus Simplicinius Genialis, the Roman army crushed the Juthungi, and Postumus proceeded to distribute the captured spoils to the legions he commanded. Saloninus, on the advice of his praetorian prefect Silvanus (who had coordinated Roman policy in Gaul alongside Postumus), demanded the transfer of the recovered booty to his residence at Colonia Claudia Ara Agrippinensium (Cologne). Postumus assembled his army and made a show of reluctantly enforcing this command, thus inviting his troops to instead throw off their allegiance to Gallienus.Drinkwater (1987), p. 89. The troops accordingly proclaimed Postumus emperor and proceeded to besiege and attack Colonia, trapping Saloninus and Silvanus. After breaching the walls of the city, Postumus had Silvanus and Saloninus killed, although his supporters later claimed that it was the native Gauls who were responsible for the murders.Southern (2001), p. 98 Later he erected a triumphal arch to celebrate his victory. =Establishment of a Gallic empire= Postumus aureus, 268, Treves, gold . Legend: POSTVMVS AVG. Postumus was immediately recognized as emperor in Gaul (except perhaps for Narbonensis), Germania Superior and Inferior, and Raetia. By 261, Britannia, Gallia Narbonensis and Hispania also acknowledged him as emperor, possibly after an expedition to Britain in the winter of 260–261.Drinkwater (1987), p. 168. He established his capital in northern Gaul, probably at Colonia Claudia Ara Agrippinensium (Cologne) or Augusta Treverorum (Trier),Drinkwater (1987), pp. 146, 167. and then proceeded to set up many of the traditional Roman legislative and executive structures.Southern (2001), p. 97 Apart from the position of emperor, he immediately assumed the office of consul alongside a colleague, Honoratianus.Potter (2004), p. 260 Like his imperial predecessors, he became the pontifex maximus of the state and assumed tribunician power each year. He is thought to have established a senate, perhaps on the basis of the Council of the Three Gauls or provincial councils,Drinkwater (1987), p. 29. and a praetorian guard, one of whose officers was to become the future Gallic emperor Victorinus.Drinkwater (1987), p. 130. Reflecting his power base, the chief members of Postumus’ administration appeared to have been of northern Gallic origin, and indeed, the entire administration soon became rapidly Gallicized.Potter (2004), p. 261. Both Victorinus and Tetricus, important members of the government, hailed from this region. Postumus represented himself as the restorer of Gaul (Restitutor Galliarum) and the bringer of security to the provinces (Salus Provinciarum) on some of his coins; prior to 10 December 261, he also took the title of Germanicus maximus, a title he earned after successfully defending Gaul against the Germans. His principal objective in assuming the purple appeared to be the restoration and defence of the Rhine frontier and the surrounding area, a task that he approached with vigour, earning the admiration of the ancient authors, who declared that he restored the security that the provinces had enjoyed in the past. So successful was he in the task of restoring peace and security to the provinces under his direct control that the coins issued by Postumus were of better workmanship and higher precious metal content than coins issued by Gallienus;Southern (2001), p. 118 his control of the Spanish and British mining regions was presumably crucial in this regard,Drinkwater (1987), p. 27. as was his employment of master minters who would have come into Gaul with Gallienus.Drinkwater (1987), p. 136. Postumus fought successful campaigns against the Franks and Alamanni in 262 and 263; following his victory over them in 263, he assumed the title Germanicus Maximus, after which his coin- types celebrated peaceful themes such as Felicitas Augusti for some time.Drinkwater (1987), pp. 30, 170. After having spent much of the last four years pushing the Franks out of Gaul, Postumus then recruited Frankish troops to fight against other Franks, probably dispersed within existing Roman army units.Southern (2001), p. 217 Scholars continue to debate whether Postumus originally intended to dislodge Gallienus from Rome or was content to rule only the western provinces. From the beginning of his usurpation, Postumus had made it clear that he had no immediate intentions to make a bid for Rome, that his priority was for Gaul. Postumus’ power base was Gaul and his main responsibility was the defense of the Rhine provinces. If he marched against Gallienus, then he would be exposing his heartland not only to the Germanic tribes but also potentially to any number of usurpers. Perhaps he hoped to achieve some official recognition from Gallienus; what is clear, however, is that Postumus was not overtly separatist and did not revive the 1st-century dream of an independent Galliarum imperium. (See Julius Sabinus and revolt of the Batavi.) The forms, titles, and administrative structures of Postumus’ principate remained conventionally Roman.Drinkwater (1987), p. 28. Milestone of Postumus c.261-269 found in Vitoria-Gasteiz, Spain. It bears the inscription: [I]MP(ERATORI) CAE[S(ARI)] [M]ARCO CA[SSIJANO] LAT[IN]IO POSTUMO AUG(USTO). =Confrontation with Gallienus= For four years Gallienus was too distracted by Germanic invasions and other usurpers in the east to turn his attention to the situation to his north and west.Potter (2004), p. 263 This changed in 265 when Gallienus launched a campaign to defeat Postumus. After some initial success against Postumus, his first attempt failed when Postumus managed to escape from a precarious situation due to the carelessness of Gallienus’ cavalry commander Aureolus,Polfer, Postumus leading to Aureolus’ demotion and eventual abandonment of Gallienus in 267. A second campaign, led by Gallienus himself, also seemed to have the advantage over Postumus, but while Gallienus was besieging a city in Gaul (perhaps Augusta TreverorumSouthern (2001), p. 100), he was wounded and forced to withdraw.Drinkwater (1987), p. 89, who cites Zonaras (12.24.13-18) as the ancient authority for these events. After his failed attempt at defeating Postumus, Gallienus was occupied with crises in the rest of his empire and did not confront Postumus again. Gallienus nevertheless did manage to wrest control of Raetia from Postumus during these years. =Final years= radiate of Postumus. Legend: IMP. C. POSTVMVS P. F. AVG. By the end of 265, Postumus’ coin issues were triumphantly commemorating the victory over Gallienus, and the festivities celebrating his quinquennalia continued into the following year.Polfer, Postumus Very little troubled the reign of Postumus from 265 to 268; archaeological evidence, such as it is, points to a general return to peace and normalcy.Drinkwater (1987), p. 231. In 266, Postumus became consul for the fourth time, taking as his colleague Marcus Piavonius Victorinus, a Gallic noble who was also a senior military officer; his selection to such a high-profile position may be seen as an attempt to broaden Postumus’ base of support.Drinkwater (1987), p. 174. The year 268 saw the issuing of the ‘Labours of Hercules’ series of gold coins in honour of Postumus’ favourite god.Drinkwater (1987), pp. 32, 174. A sudden debasement of the coinage later that year shows that Postumus was facing increasing financial difficulties, due perhaps to a disruption of silver production in the Spanish minesDrinkwater (1987), p. 210. or the need to buy off an increasingly discontented army.Polfer, Postumus Such discontent must probably have been due to the army’s frustration with Postumus’ failure to take advantage of a golden opportunity to move against Gallienus in 268.Drinkwater (1987), p. 32. Aureolus, the general who was in command of Mediolanum (Milan) in Gallienus’ interest, rebelled and ultimately declared for Postumus. The city of Mediolanum and its north Italian and Raetian hinterland would have been critical to Postumus if he planned to march on Rome. For whatever reason, Postumus failed to support Aureolus, who was besieged by Gallienus.Southern (2001), p. 106 Before the end of the northern summer in 268, the events at Mediolanum were to see the assassination of Gallienus, the defeat of Aureolus, and the accession of Claudius II.Potter (2004), p. 264 It also triggered a sequence of events that would see the end of Postumus’ rule in Gaul. =Fall= Aureus of Postumus, within a pendant. Legend: POSTVMVS PIVS AVG. Postumus assumed his fifth consulship on 1 January 269, but the army in Germania Superior raised a usurper in early 269. Laelianus, one of Postumus’ top military leaders and the governor of Germania Superior, was declared emperor in Mogontiacum (Mainz) by the local garrison and surrounding troops (Legio XXII Primigenia).Potter (2004), p. 265 Although Postumus was able to capture Mogontiacum and kill Laelianus within a few months, he was unable to control his own troops, who wished to put Mogontiacum to the sack. When Postumus tried to restrain them, his men turned on him and killed him.Aurelius Victor 33.8; Eutropius 9.9.1 The mutineers set up Marius, a common soldier, as emperor. Marius held sway for a short while before being overthrown by Victorinus, Postumus’ erstwhile colleague in the consulship and tribune of the praetorian guard.Drinkwater (1987), p. 35. In the meantime, the Gallic Empire lost Hispania.Potter (2004), p. 266 Historical sources Most of the ancient literary references to Postumus come from the works thought to be based on the Enmannsche Kaisergeschichte (Aurelius Victor, Epitome de Caesaribus, Eutropius, and the Historia Augusta, in the last of which Postumus is listed among the Thirty Tyrants). He also figures in the works of Zosimus and Zonaras.Drinkwater (1987), p. 45. Coinage Postumus has been of particular interest to numismatists, in light of the high quality and relative abundance of his coin issues. His ‘Labours of Hercules’ series is particularly renowned. Notes References ;Primary sources * Aurelius Victor, Liber de Caesaribus * Epitome de Caesaribus (sometimes attributed to Aurelius Victor) * Eutropius, Brevarium, Book 9 * Historia Augusta, Tyranni_XXX*.html The Thirty Tyrants * Joannes Zonaras, Compendium of History extract: Zonaras: Alexander Severus to Diocletian: 222–284 * Zosimus, Historia Nova ;Secondary sources * Bakker, Lothar. (1993), "Raetien unter Postumus. Das Siegesdenkmal einer Juthungenschlacht im Jahre 260 n. Chr. aus Augsburg." Germania 71, pp. 369–386. Jones, A.H.M., Martindale, J.R. (1971), The Prosopography of the Later Roman Empire, Vol. I: AD260-395, Cambridge University Press * Polfer, Michel (2000), "Postumus (A.D. 260-269)", De Imperatoribus Romanis * * External links * Partial coinage listing featuring Postumus Category:269 deaths Category:Year of birth unknown Category:Gallic emperors Category:Imperial Roman consuls Category:3rd-century Roman usurpers Category:3rd-century murdered monarchs Category:Germanic warriors Category:Thirty Tyrants (Roman) Category:3rd-century monarchs in Europe Category:Batavian people Category:Germanic rulers Category:Roman governors of Germania Inferior Category:Cassianii Category:Murdered Roman emperors "