Flowering time responses to warming drive reproductive fitness in a changing Arctic.

Background And Aims: The Arctic is warming at an alarming rate, leading to earlier spring conditions and plant phenology. It is often unclear to what degree changes in reproductive fitness (flower, fruit, seed production) are a direct response to warming versus an indirect response through shifting phenology. This study aims to quantify the relative importance of these direct and indirect pathways and project the net effects of warming on plant phenology and reproductive fitness under current and future climate scenarios.

Experimental warming differentially affects vegetative and reproductive phenology of tundra plants.

Rapid climate warming is altering Arctic and alpine tundra ecosystem structure and function, including shifts in plant phenology. While the advancement of green up and flowering are well-documented, it remains unclear whether all phenophases, particularly those later in the season, will shift in unison or respond divergently to warming. Here, we present the largest synthesis to our knowledge of experimental warming effects on tundra plant phenology from the International Tundra Experiment.

Eccentric Resistance Training in Youth: A Survey of Perceptions and Current Practices by Strength and Conditioning Coaches.

Background: Eccentric resistance training (ERT) in youth is advocated for aiding performance and injury risk. However, research investigating the applied practices of ERT in youth is in its infancy. In this study, we surveyed the perceptions and practices of practitioners utilizing ERT in youth to provide an understanding of its current application in practice.

Local snow melt and temperature-but not regional sea ice-explain variation in spring phenology in coastal Arctic tundra.

The Arctic is undergoing dramatic environmental change with rapidly rising surface temperatures, accelerating sea ice decline and changing snow regimes, all of which influence tundra plant phenology. Despite these changes, no globally consistent direction of trends in spring phenology has been reported across the Arctic. While spring has advanced at some sites, spring has delayed or not changed at other sites, highlighting substantial unexplained variation.

Author Correction: Warming shortens flowering seasons of tundra plant communities.

In the version of this Article originally published, the following sentence was missing from the Acknowledgements: "This work was supported by the Norwegian Research Council SnoEco project, grant number 230970". This text has now been added.

Warming shortens flowering seasons of tundra plant communities.

Advancing phenology is one of the most visible effects of climate change on plant communities, and has been especially pronounced in temperature-limited tundra ecosystems. However, phenological responses have been shown to differ greatly between species, with some species shifting phenology more than others. We analysed a database of 42,689 tundra plant phenological observations to show that warmer temperatures are leading to a contraction of community-level flowering seasons in tundra ecosystems due to a greater advancement in the flowering times of late-flowering species than early-flowering species.

Relationships Between Reactive Agility Movement Time and Unilateral Vertical, Horizontal, and Lateral Jumps.

Henry, GJ, Dawson, B, Lay, BS, and Young, WB. Relationships between reactive agility movement time and unilateral vertical, horizontal, and lateral jumps. J Strength Cond Res 30(9): 2514-2521, 2016-This study compared reactive agility movement time and unilateral (vertical, horizontal, and lateral) jump performance and kinetics between dominant and nondominant legs in Australian rules footballers (n = 31) to investigate the role of leg strength characteristics in reactive agility performance.

Decision-making accuracy in reactive agility: quantifying the cost of poor decisions.

Decision-making accuracy and the time cost of incorrect responses was compared between higher- (n = 14) and lower-standard (n = 14) Australian footballers during reactive agility tasks incorporating feint and nonfeint scenarios. Accuracy was assessed as whether the subject turned in the correct direction to each stimulus. With skill groups pooled, decision accuracy at the first (or only) stimulus (decision time 1) was 94 ± 7%, and it decreased to 83 ± 20% for the second stimulus (decision time 2; p = 0.

Effects of a feint on reactive agility performance.

This study compared reactive agility between higher-standard (n = 14) and lower-standard (n = 14) Australian footballers using a reactive agility test incorporating a life-size video image of another player changing direction, including and excluding a feint. Mean agility time in the feint trials was 34% (509 ± 243 ms; p < 0.001; effect size 3.

Validity of a reactive agility test for Australian football.

Purpose: To study the validity of a video-based reactive agility test in Australian footballers.

Methods: 15 higher performance, 15 lower performance, and 12 nonfootballers completed a light-based reactive agility test (LRAT), a video-based reactive agility test (VRAT), and a planned test (PLAN).

Results: With skill groups pooled, agility time in PLAN (1346 ± 66 ms) was significantly faster (P = .

Effect of caffeine on reactive agility time when fresh and fatigued.

Purpose: This study examined the effects of acute caffeine ingestion on agility performance and decision-making accuracy after simulated team-sport exercise.

Methods: Using a randomized, double-blinded, counterbalanced design, 10 moderately trained male team-sport athletes ingested either caffeine (6 mg·kg(-1)) or placebo (dextrose) 60 min before completing an 80-min (4 × 20 min) simulated team-game, intermittent running protocol. Interspersed between each exercise quarter was a reactive agility test (RAT) consisting of five trials where measures of total time (TT), reactive agility (RA) time, decision time (DT), movement time (MT), and decision-making accuracy were obtained.

Plant community responses to experimental warming across the tundra biome.

Recent observations of changes in some tundra ecosystems appear to be responses to a warming climate. Several experimental studies have shown that tundra plants and ecosystems can respond strongly to environmental change, including warming; however, most studies were limited to a single location and were of short duration and based on a variety of experimental designs. In addition, comparisons among studies are difficult because a variety of techniques have been used to achieve experimental warming and different measurements have been used to assess responses.

Impacts of warming and fertilization on nitrogen-fixing microbial communities in the Canadian High Arctic.

The impacts of simulated climate change (warming and fertilization treatments) on diazotroph community structure and activity were investigated at Alexandra Fiord, Ellesmere Island, Canada. Open Top Chambers, which increased growing season temperatures by 1-3 degrees C, were randomly placed in a dwarf-shrub and cushion-plant dominated mesic tundra site in 1995. In 2000 and 2001 20N:20P2O5:20K2O fertilizer was applied at a rate of 5 gm(-2) year(-1).