Antarctic and Southern Ocean influences on Late Pliocene global cooling.

The influence of Antarctica and the Southern Ocean on Late Pliocene global climate reconstructions has remained ambiguous due to a lack of well-dated Antarctic-proximal, paleoenvironmental records. Here we present ice sheet, sea-surface temperature, and sea ice reconstructions from the ANDRILL AND-1B sediment core recovered from beneath the Ross Ice Shelf. We provide evidence for a major expansion of an ice sheet in the Ross Sea that began at ∼3.3 Ma, followed by a coastal sea surface temperature cooling of ∼2.5 °C, a stepwise expansion of sea ice, and polynya-style deep mixing in the Ross Sea between 3.3 and 2.5 Ma. The intensification of Antarctic cooling resulted in strengthened westerly winds and invigorated ocean circulation. The associated northward migration of Southern Ocean fronts has been linked with reduced Atlantic Meridional Overturning Circulation by restricting surface water connectivity between the ocean basins, with implications for heat transport to the high latitudes of the North Atlantic. While our results do not exclude low-latitude mechanisms as drivers for Pliocene cooling, they indicate an additional role played by southern high-latitude cooling during development of the bipolar world.

Effects of Three Recovery Protocols on Range of Motion, Heart Rate, Rating of Perceived Exertion, and Blood Lactate in Baseball Pitchers During a Simulated Game.

Baseball pitching has been described as an anaerobic activity from a bioenergetics standpoint with short bouts of recovery. Depending on the physical conditioning and muscle fiber composition of the pitcher as well as the number of pitches thrown per inning and per game, there is the possibility of pitchers fatiguing during a game, which could lead to a decrease in pitching performance. Therefore, the purpose of this study was to evaluate the effects of 3 recovery protocols: passive recovery, active recovery (AR), and electrical muscle stimulation (EMS) on range of motion (ROM), heart rate (HR), rating of perceived exertion (RPE), and blood lactate concentration in baseball pitchers during a simulated game. Twenty-one Division I intercollegiate baseball pitchers (age = 20.4 ± 1.4 years; height = 185.9 ± 8.4 cm; weight = 86.5 ± 8.9 kg; percent body fat = 11.2 ± 2.6) volunteered to pitch 3 simulated 5-inning games, with a maximum of 70 fastballs thrown per game while wearing an HR monitor. Range of motion was measured pre, post, and 24 hours postpitching for shoulder internal and external rotation at 90° and elbow flexion and extension. Heart rate was recorded after each pitch and after every 30 seconds of the 6-minute recovery period. Rating of perceived exertion was recorded after the last pitch of each inning and after completing each 6-minute recovery period. Immediately after throwing the last pitch of each inning, postpitching blood lactate concentration (PPLa-) was measured. At the end of the 6-minute recovery period, before the next inning started, postrecovery blood lactate concentration (PRLa-) was measured. Pitchers were instructed to throw each pitch at or above 95% of their best-pitched fastball. This was enforced to ensure that each pitcher was throwing close to maximal effort for all 3 simulated games. All data presented represent group mean values. Results revealed that the method of recovery protocol did not significantly influence ROM (p > 0.05); however, it did significantly influence blood lactate concentration (p < 0.001), HR (p < 0.001), and RPE (p = 0.01). Blood lactate concentration significantly decreased from postpitching to postrecovery in the EMS recovery condition (p < 0.001), but did not change for either the active (p = 0.04) or the passive (p = 0.684) recovery conditions. Rating of perceived exertion decreased from the postpitching to postrecovery in both the passive and EMS recovery methods (p < 0.001), but did not decrease for AR (p = 0.067). Heart rate decreased for all conditions from postpitching to postrecovery (p < 0.001). The use of EMS was the most effective method at reducing blood lactate concentration after 6 minutes of recovery during a simulated game (controlled setting). Although EMS significantly reduced blood lactate concentrations after recovery, blood lactate concentrations after pitching in the simulated games were never high enough to cause skeletal muscle fatigue and decrease pitching velocity. If a pitcher were to throw more than 14 pitches per inning, throw more total pitches than normal per game, and have blood lactate concentrations increase higher than in the simulated games in this study, the EMS recovery protocol may be beneficial to pitching performance by aiding recovery. This could potentially reduce some injuries associated with skeletal muscle fatigue during pitching, may allow a pitcher throw more pitches per game, and may reduce the number of days between pitching appearances.

Effect of three different between-inning recovery methods on baseball pitching performance.

A decrease in blood hydrogen ions (H) may allow for the recovery of a muscle, which should allow for greater performance in subsequent activity. The purpose of this study was to determine which of 3 forms of recovery were the most effective after an inning of pitching in baseball. Three different measurements were used to determine which recovery method was most effective; the difference in blood lactate (BLa) levels was used as a biological measurement, average pitching speed was the physiological measurement, and the psychological measurement was done on how the pitchers perceived their pitching and recovery. The recovery methods that were used were passive recovery (PR), active recovery (AR), and electromuscular stimulation (EMS). Seven college men aged 21 (±2 years) who were National Collegiate Athletic Association Division II college baseball pitchers were assessed during game play simulations. Blood lactate levels decreased significantly from the premeasurement to the postmeasurement with the EMS recovery method (p < 0.0005); however, BLa did not change for PR (p = 0.017) or AR (p = 0.134). Perceived recovery was also found to be best in the EMS and PR conditions. These findings suggest that EMS is an effective recovery method between innings of pitching.