Biceps femoris long head muscle and aponeurosis geometry in males with and without a history of hamstring strain injury.

Objectives: Hamstring strain injuries (HSIs) commonly affect the proximal biceps femoris long head (BFlh) musculotendinous junction. Biomechanical modeling suggests narrow proximal BFlh aponeuroses and large muscle-to-aponeurosis width ratios increase localized tissue strains and presumably risk of HSI. This study aimed to determine if BFlh muscle and proximal aponeurosis geometry differed between limbs with and without a history of HSI.

Hamstring and knee injuries are associated with isometric hip and trunk muscle strength in elite Australian Rules and Rugby League players.

Objectives: This study investigated relationships between isometric trunk and hip extensor strength, lumbar muscle morphology, and the risk of hamstring and knee ligament injuries in Australian Football League and National Rugby League players.

Design: Prospective cohort study.

Methods: Trunk and hip extensor strength, multifidus and quadratus lumborum cross-sectional area were measured during the 2020 pre-season.

Gluteal Muscle Forces during Hip-Focused Injury Prevention and Rehabilitation Exercises.

Purpose: This study aimed to compare and rank gluteal muscle forces in eight hip-focused exercises performed with and without external resistance and describe the underlying fiber lengths, velocities, and muscle activations.

Methods: Motion capture, ground reaction forces, and electromyography (EMG) were used as input to an EMG-informed neuromusculoskeletal model to estimate gluteus maximus, medius, and minimus muscle forces. Participants were 14 female footballers (18-32 yr old) with at least 3 months of lower limb strength training experience.

Intrinsic motor neuron excitability is increased after resistance training in older adults.

This study investigated the effects of high-intensity resistance training on estimates of the motor neuron persistent inward current (PIC) in older adults. Seventeen participants (68.5 ± 2.

Effects of three neuromuscular electrical stimulation methods on muscle force production and neuromuscular fatigue.

This study compared the acute responses of three neuromuscular electrical stimulation (NMES) methods on muscle torque-time integral (TTI) and neuromuscular fatigue. Narrow-pulse (0.2 ms; NP), wide-pulse (1 ms; WP), and tendon vibration superimposed onto wide-pulse (WP + VIB)-NMES conditions were applied to sixteen healthy individuals (n = 16) in three separate sessions in a randomized order.

Do motoneuron discharge rates slow with aging? A systematic review and meta-analysis.

Nervous system maladaptation is linked to the loss of maximal strength and motor control with aging. Motor unit discharge rates are a critical determinant of force production; thus, lower discharge rates could be a mechanism underpinning maximal strength and motor control losses during aging. This meta-analysis summarized the findings of studies comparing motor unit discharge rates between young and older adults, and examined the effects of the selected muscle and contraction intensity on the magnitude of discharge rate difference between these two groups.

Predicting Noncontact Lower Limb Injury Using Lumbar Morphology in Professional Australian Football and Rugby League Players.

Introduction: Noncontact lower limb injuries are common within the Australian Football League (AFL) and National Rugby League (NRL). Smaller (<8.5 cm2) lumbar multifidus at the fifth vertebra (LM L5) and larger (>8.

Runners with mid-portion Achilles tendinopathy have greater triceps surae intracortical inhibition than healthy controls.

Objectives: This study aimed to investigate short-interval intracortical inhibition (SICI) and muscle function in the triceps surae of runners with mid-portion Achilles tendinopathy (AT).

Methods: Runners with (n = 11) and without (n = 13) AT were recruited. Plantar flexor isometric peak torque and rate of torque development (RTD) were measured using an isokinetic dynamometer.

Lower knee flexion and hip extension rate of torque development in athletes with previous hamstring strain injury.

Persistent deficits in strength and voluntary activation have been observed in athletes with a history of hamstring strain injury. The mechanisms contributing to these deficits are poorly understood and consequently may not be appropriately addressed during rehabilitation. This study aimed to investigate the impact of intended knee flexor contraction mode (concentric, eccentric or isometric) on the rate of torque development and surface electromyography (sEMG) rise in athletes with and without a history of unilateral hamstring strain injury.

Intrinsic motoneuron excitability is reduced in soleus and tibialis anterior of older adults.

Age-related deterioration within both motoneuron and monoaminergic systems should theoretically reduce neuromodulation by weakening motoneuronal persistent inward current (PIC) amplitude. However, this assumption remains untested. Surface electromyographic signals were collected using two 32-channel electrode matrices placed on soleus and tibialis anterior of 25 older adults (70 ± 4 years) and 17 young adults (29 ± 5 years) to investigate motor unit discharge behaviors.

Anterior Cruciate Ligament Reconstruction Increases the Risk of Hamstring Strain Injury Across Football Codes in Australia.

Objective: The aim of this study was to determine the impacts of anterior cruciate ligament reconstruction (ACLR) and recent (< 12 months) hamstring strain injury (HSI) on (1) future HSI risk, and (2) eccentric knee flexor strength and between-limb imbalance during the Nordic hamstring exercise. A secondary goal was to examine whether eccentric knee flexor strength was a risk factor for future HSI in athletes with prior ACLR and/or HSI.

Methods: In this prospective cohort study, 531 male athletes had preseason eccentric knee flexor strength tests.

Sprinting Biomechanics and Hamstring Injuries: Is There a Link? A Literature Review.

Hamstring strain injury (HSI) is a common and costly injury in many sports such as the various professional football codes. Most HSIs have been reported to occur during high intensity sprinting actions. This observation has led to the suggestion that a link between sprinting biomechanics and HSIs may exist.

Sprinting technique and hamstring strain injuries: A concept mapping study.

Objective: The aim of this study was to explore expert opinion to identify the components of sprinting technique they believed to be risk factors for hamstring strain injuries (HSI).

Design: Mixed-method research design.

Methods: The Concept Systems groupwisdom™ web platform was used to analyse and collect data.

Muscle Activity and Activation in Previously Strain-Injured Lower Limbs: A Systematic Review.

Background: Lower limb muscle strain injury is highly prevalent in running-based sports and is considered a risk factor for recurrent injury. It is possible that differences in muscle activity and activation in previously strain-injured limbs may contribute to the elevated risk of reinjury.

Objectives: To systematically review available literature investigating whether muscle activity and/or activation is different in previously strain-injured muscles compared to contralateral uninjured muscles or uninjured controls.

Hamstring and gluteal activation during high-speed overground running: Impact of prior strain injury.

This study examined the spatial patterns of hamstring and gluteal muscle activation during high-speed overground running in limbs with and without aprior hamstring strain injury. Ten active males with arecent (<18 month) unilateral biceps femoris long head (BFLH) strain injury underwent functional magnetic resonance imaging before and immediately after arepeat-sprint running protocol. Transverse relaxation (T2) time, an index of muscle activation, of the BFLH and short head (BFSH), semitendinosus (ST), semimembranosus (SM), gluteus maximus (GMAX) and medius (GMED) was assessed pre-post exercise.

Estimates of persistent inward currents increase with the level of voluntary drive in low-threshold motor units of plantar flexor muscles.

This study tested whether estimates of persistent inward currents (PICs) in the human plantar flexors would increase with the level of voluntary drive. High-density surface electromyograms were collected from soleus and gastrocnemius medialis of 21 participants (29.2 ± 2.

The effect of previous shoulder pain on supraspinatus tendon thickness changes following swimming practice.

Objectives: To assess if swimming practice results in changes in supraspinatus tendon thickness, acromiohumeral distance, and occupational ratio in shoulders of elite swimmers with and without a history of shoulder pain.

Design: Case-Control study.

Methods: A convenience sample of fifty elite swimmers (14-22 years) were recruited for this study.

Is power training effective to produce muscle hypertrophy in older adults? A systematic review and meta-analysis.

Power training has been suggested to be effective in improving strength, power, and functional capacity in older adults. However, there is still a lack of systematic investigations reporting its effectiveness for muscle hypertrophy. Thus, this study investigated the effect of power training on muscle hypertrophy and compared its magnitude with traditional moderate-velocity resistance training in older adults.

Effects of resistance training concentric velocity on older adults' functional capacity: A systematic review and meta-analysis of randomised trials.

Reduced levels of functional capacity in older adults are related to lower quality of life, frailty, and sarcopenia, and can increase risk of falling, fractures and hospitalisation. Resistance training is an effective method to attenuate age-related functional declines. Based on the findings that muscle power and explosive strength are strongly associated with functional performance in older adults, it has been suggested that fast-intended-velocity resistance training may elicit greater improvements in functional capacity when compared to moderate-velocity resistance training.

Hamstring muscle activation and morphology are significantly altered 1-6 years after anterior cruciate ligament reconstruction with semitendinosus graft.

Purpose: Harvest of the semitendinosus (ST) tendon for anterior cruciate ligament reconstruction (ACLR) causes persistent hypotrophy of this muscle even after a return to sport, although it is unclear if hamstring activation patterns are altered during eccentric exercise. It was hypothesised that in comparison with contralateral control limbs, limbs with previous ACLR involving ST grafts would display (i) deficits in ST activation during maximal eccentric exercise; (ii) smaller ST muscle volumes and anatomical cross-sectional areas (ACSAs); and (iii) lower eccentric knee flexor strength.

Methods: Fourteen athletes who had successfully returned to sport after unilateral ACLR involving ST tendon graft were recruited.

Effect of concentric and eccentric hamstring training on sprint recovery, strength and muscle architecture in inexperienced athletes.

Objectives: To investigate whether five-weeks of concentric (CON) or eccentric (ECC) hamstring strength training have different effects on recovery from sprint running, eccentric strength and architecture of the biceps femoris long head (BF).

Design: Cohort study.

Methods: Thirty males (age, 22.

Hamstring Muscle Use in Women During Hip Extension and the Nordic Hamstring Exercise: A Functional Magnetic Resonance Imaging Study.

Background Understanding hamstring muscle activation patterns in resistance training exercises may have implications for the design of strength training and injury prevention programs. Unfortunately, surface electromyography studies have reported conflicting results regarding hamstring muscle activation patterns in women. Objectives To determine the spatial patterns of hamstring muscle activity during the 45° hip extension and Nordic hamstring exercises in women using functional magnetic resonance imaging (fMRI).