Knee valgus in self-initiated vertical jump landings: developmental and gender comparisons

The study examined gender and developmental differences in knee valgus angle and external knee valgus moment at the time of maximal vertical ground reaction force (MGRFz) in self-initiated vertical jump (VJ) landings. Fifty-six subjects grouped by age (pre-pubescent (8-11 yrs); post-pubescent (19-29 yrs)) and gender jumped for a ball set at 50% of their maximum VJ height then landed on two feet with only their dominant foot on the force plate. Statistical analyses of motion analysis (3-D) and GRF data showed that children had greater valgus angles (p = .003) and moments (p = .026) at MGRFz compared to adults. Females had greater (p = .016) valgus moments than males, but similar valgus angles at MGRFz. It will be important to ensure that as both boys and girls progress through puberty they develop an ability to offset high valgus moments and land with good lower extremity alignment

Knee valgus in self-initiated vertical jump landings: developmental and gender comparisons

The study examined gender and developmental differences in knee valgus angle and external knee valgus moment at the time of maximal vertical ground reaction force (MGRFz) in self-initiated vertical jump (VJ) landings. Fifty-six subjects grouped by age (pre-pubescent (8-11 yrs); post-pubescent (19-29 yrs)) and gender jumped for a ball set at 50% of their maximum VJ height then landed on two feet with only their dominant foot on the force plate. Statistical analyses of motion analysis (3-D) and GRF data showed that children had greater valgus angles (p = .003) and moments (p = .026) at MGRFz compared to adults. Females had greater (p = .016) valgus moments than males, but similar valgus angles at MGRFz. It will be important to ensure that as both boys and girls progress through puberty they develop an ability to offset high valgus moments and land with good lower extremity alignment

KNEE VALGUS IN SELF-INITIATED VERTICAL JUMP LANDINGS: DEVELOPMENTAL AND GENDER COMPARISIONS

The study examined gender and developmental differences in knee valgus angle and external knee valgus moment at the time of maximal vertical ground reaction force (MGRFz) in self-initiated vertical jump (VJ) landings. Fifty-six subjects grouped by age (pre-pubescent (8-11 yrs); post-pubescent (19-29 yrs)) and gender jumped for a ball set at 50% of their maximum VJ height then landed on two feet with only their dominant foot on the force plate. Statistical analyses of motion analysis (3-D) and GRF data showed that children had greater valgus angles (p = .003) and moments (p = .026) at MGRFz compared to adults. Females had greater (p = .016) valgus moments than males, but similar valgus angles at MGRFz. It will be important to ensure that as both boys and girls progress through puberty they develop an ability to offset high valgus moments and land with good lower extremity alignment

Loading rate in self-initiated vertical jump landings: developmental and gender comparisons

The study compared gender and developmental differences in vertical loading rate upon a two-footed landing from a self-initiated VJ. Fifty-seven subjects grouped by age (pre-pubescent (8-11 yrs); post-pubescent (19-29 yrs)) and gender consented to participate. Subjects jumped for a ball set at 50% of their maximum VJ height, and landed on two feet, facing forward, with only their dominant foot on the force plate. Motion analysis (3-D) and ground reaction force (GRF) data were collected. Statistical analyses indicated significant developmental differences in vertical loading rate normalized to kinetic energy, but no gender differences. Children may have higher loading rates because they lack the experience, strength, and associated neuromuscular patterns that prepare them to modulate force as adults do

LOADING RATE IN SELF-INITIATED VERTICAL JUMP LANDINGS: DEVELOPMENTAL AND GENDER COMPARISONS

The study compared gender and developmental differences in vertical loading rate upon a two-footed landing from a self-initiated VJ. Fifty-seven subjects grouped by age (pre-pubescent (8-11 yrs); post-pubescent (19-29 yrs)) and gender consented to participate. Subjects jumped for a ball set at 50% of their maximum VJ height, and landed on two feet, facing forward, with only their dominant foot on the force plate. Motion analysis (3-D) and ground reaction force (GRF) data were collected. Statistical analyses indicated significant developmental differences in vertical loading rate normalized to kinetic energy, but no gender differences. Children may have higher loading rates because they lack the experience, strength, and associated neuromuscular patterns that prepare them to modulate force as adults do

Pure O-sequences and matroid h-vectors

We study Stanley's long-standing conjecture that the h-vectors of matroid simplicial complexes are pure O-sequences. Our method consists of a new and more abstract approach, which shifts the focus from working on constructing suitable artinian level monomial ideals, as often done in the past, to the study of properties of pure O-sequences. We propose a conjecture on pure O-sequences and settle it in small socle degrees. This allows us to prove Stanley's conjecture for all matroids of rank 3. At the end of the paper, using our method, we discuss a first possible approach to Stanley's conjecture in full generality. Our technical work on pure O-sequences also uses very recent results of the third author and collaborators.Comment: Contains several changes/updates with respect to the previous version. In particular, a discussion of a possible approach to the general case is included at the end. 13 pages. To appear in the Annals of Combinatoric

Emergent Access to the Airway and Chest in American Football Players

American football has the highest rate of fatalities and catastrophic injuries of any US sport. The equipment designed to protect athletes from these catastrophic events challenges the ability of medical personnel to obtain neutral spine alignment and immobilization during airway and chest access for emergency life-support delivery

Early Results of a Helmetless-Tackling Intervention to Decrease Head Impacts in Football Players

To test a helmetless-tackling behavioral intervention for reducing head impacts in National Collegiate Athletic Association Division I football players

National Athletic Trainers' Association Position Statement: Preventing Sudden Death in Sports

To present recommendations for the prevention and screening, recognition, and treatment of the most common conditions resulting in sudden death in organized sports