A Preseason Training Program With the Nordic Hamstring Exercise Increases Eccentric Knee Flexor Strength and Fascicle Length in Professional Female Soccer Players

# Background Training programs that include the Nordic hamstring exercise (NHE) have been shown to increase eccentric knee flexor strength and biceps femoris fascicle length in male athletes. However, the effect of NHE on female athletes remains unknown. # Purpose To investigate the collective and individual responses of professional female soccer players engaged in a preseason training program with the NHE regarding eccentric knee flexor strength and biceps femoris long head fascicle length. # Study Design Quasi-experimental study. # Methods Sixteen amateur female soccer players (without a NHE training routine) were evaluated 8-weeks apart to: (1) assess reliability of eccentric knee flexor strength and biceps femoris fascicle length measures; and (2) determine the typical error of measures that would be used to discriminate training responders and non-responders. The NHE training group had 17 professional female soccer players who performed an 8-week training program with the NHE during preseason. Within-group analysis was performed with paired sample t-tests (pre- vs. post-training), and individual responses were determined using the typical error criteria. # Results The non-trained group’s data demonstrated that measures of strength (ICC=0.82-0.87, typical error = 12-13 N) and fascicle length (ICC=0.92-0.97; typical error = 0.19-0.38 cm) were reliable. In the NHE training group, both limbs increased the eccentric knee flexor strength (\~13%; ES=0.74-0.82) and the biceps femoris fascicle length (\~6%; ES=0.44-0.65). Twelve players (\~71%) were considered responders to the NHE training program for the eccentric knee flexor strength, while eight athletes (\~47%) were responders for the biceps femoris fascicle length. # Conclusion The 8-week preseason training program with the NHE increased both eccentric knee flexor strength and biceps femoris fascicle length in professional female soccer players. More than two-thirds of players demonstrated a meaningful increase in eccentric strength, while nearly half achieved consistent fascicle length increases with the NHE training

Sex-related differences in muscular factors previously identified in the literature as potentially associated with hamstring strain injury in professional football players

The purpose of this study was to assess if differences in hamstring strength, hamstring-to-quadriceps (H:Q) strength ratio, and biceps femoris long head (BFLH) fascicle length exist between male and female professional football (soccer) players. One-hundred professional footballers participated in this cross-sectional study: 50 men and 50 women. Ultrasound images of BFLH muscle and isokinetic dynamometry tests were performed. Men were stronger than women for hamstring concentric (2.01 ± 0.21 Nm/kg vs. 1.55 ± 0.23 Nm/kg; p < 0.001; large effect size, 2.08) and eccentric (2.87 ± 0.45 Nm/kg vs. 2.39 ± 0.32 Nm/kg; p < 0.001; large effect size, 1.23) peak torques. There was no sex-related difference for H:Q conventional ratio (concentric/concentric; 0.55 ± 0.06 vs. 0.55 ± 0.07); but women presented greater H:Q functional ratio (eccentric/concentric; 0.78 ± 0.12 vs. 0.85 ± 0.09; p = 0.003; moderate effect size, 0.66). Men and women presented similar BFLH fascicle length: 0.24 ± 0.05 vs. 0.23 ± 0.05 (values normalized by muscle length). Among the muscular factors assessed in this study, men presented stronger hamstring muscles, women presented greater H:Q functional ratio, and there was no sex-related differences for H:Q conventional ratio or BFLH fascicle length.info:eu-repo/semantics/publishedVersio

Neuromuscular Factors Related to Hamstring Muscle Function, Performance and Injury

Hamstring function is influenced by a number of neural, architectural and morphological factors, and the adaptability of these characteristics has important implications for optimizing performance and reducing injury risk. High rates of maximal or near-maximal hamstring force development are required to generate peak horizontal velocities during running, and this is largely determined by the extent to which these muscles can be voluntarily activated. Greater eccentric hamstring strength also correlates with better acceleration capacity and likely improves the ability to decelerate the lower limb during the presumably injurious terminal swing phase of high-speed running. The intra- and intermuscular coordination of the hamstrings appears to influence both hamstring muscle fatiguability and the risk of muscle strain injury. Muscle volume and architectural features such as fascicle length and pennation angle also influence hamstring function, and these vary considerably between hamstring muscles, between individuals and with training status. The adaptability of these features has been explored to a significant extent in recent times, and careful exercise selection allows selective targeting of individual hamstring muscles or muscle segments and this appears to influence the pattern of chronic adaptations such as muscle hypertrophy. Short fascicles within the often-injured long head of biceps femoris may predispose athletes to strain injury but these appear to respond in a contraction-mode-specific manner; lengthening after eccentric training and shortening after concentric training of 4 or more weeks. Conventional training with eccentric and concentric phases in each repetition can also lengthen fascicles, possibly in an excursion (muscle length)-dependent manner. A large biceps femoris muscle to proximal aponeurosis width ratio has been proposed as a potential risk factor for hamstring strain injury, although this is only supported by biomechanical modelling at the time of writing. High levels of anterior pelvic tilt and lateral trunk flexion during sprint running may also predispose athletes to hamstring strain injury, although the quantity of evidence for this is small at the moment. At present, the optimal methods for altering coordination and running technique are not known

Optimising Hamstring Strength and Function for Performance After Hamstring Injury

Hamstring strain injury often results in neuromuscular performance deficits that persist beyond rehabilitation and the return to full training and competitive sport. It seems appropriate to address these deficits as a part of a sport-specific training program which primarily aims to enhance performance. Prolonged deficits in horizontal ground reaction forces in sprinting, repeat sprint performance, knee flexor eccentric strength and biceps femoris long head fascicle lengths have been observed in multiple studies of hamstring strain injury. Why such deficits persist beyond the return to sport is not known, although persistent neuromuscular inhibition of the injured muscles has been proposed. There is limited and mixed evidence for sprint running kinematic (technique) differences between previously injured and uninjured limbs or athletes, although more work in this area seems warranted. While there is some uncertainty about the optimal mix of methods for addressing the aforementioned deficits, sport-specific running programs in conjunction with continued monitoring of acceleration phase sprint performance and repeated sprint ability seem appropriate. Heavy strength training with at least some eccentrically biased exercises is also recommended to address deficits in eccentric strength and muscle fascicle lengths

NEOTROPICAL XENARTHRANS: a data set of occurrence of xenarthran species in the Neotropics

Xenarthrans—anteaters, sloths, and armadillos—have essential functions for ecosystem maintenance, such as insect control and nutrient cycling, playing key roles as ecosystem engineers. Because of habitat loss and fragmentation, hunting pressure, and conflicts with domestic dogs, these species have been threatened locally, regionally, or even across their full distribution ranges. The Neotropics harbor 21 species of armadillos, 10 anteaters, and 6 sloths. Our data set includes the families Chlamyphoridae (13), Dasypodidae (7), Myrmecophagidae (3), Bradypodidae (4), and Megalonychidae (2). We have no occurrence data on Dasypus pilosus (Dasypodidae). Regarding Cyclopedidae, until recently, only one species was recognized, but new genetic studies have revealed that the group is represented by seven species. In this data paper, we compiled a total of 42,528 records of 31 species, represented by occurrence and quantitative data, totaling 24,847 unique georeferenced records. The geographic range is from the southern United States, Mexico, and Caribbean countries at the northern portion of the Neotropics, to the austral distribution in Argentina, Paraguay, Chile, and Uruguay. Regarding anteaters, Myrmecophaga tridactyla has the most records (n = 5,941), and Cyclopes sp. have the fewest (n = 240). The armadillo species with the most data is Dasypus novemcinctus (n = 11,588), and the fewest data are recorded for Calyptophractus retusus (n = 33). With regard to sloth species, Bradypus variegatus has the most records (n = 962), and Bradypus pygmaeus has the fewest (n = 12). Our main objective with Neotropical Xenarthrans is to make occurrence and quantitative data available to facilitate more ecological research, particularly if we integrate the xenarthran data with other data sets of Neotropical Series that will become available very soon (i.e., Neotropical Carnivores, Neotropical Invasive Mammals, and Neotropical Hunters and Dogs). Therefore, studies on trophic cascades, hunting pressure, habitat loss, fragmentation effects, species invasion, and climate change effects will be possible with the Neotropical Xenarthrans data set. Please cite this data paper when using its data in publications. We also request that researchers and teachers inform us of how they are using these data