Lombaires, Contraintes Rachidiennes & Prévention de la Lombalgie

It has been suggested that deep squats could cause an increased injury risk of the lumbar spine and the knee joints. Avoiding deep flexion has been recommended to minimize the magnitude of knee-joint forces. Unfortunately this suggestion has not taken the influence of the wrapping effect, functional adaptations and soft tissue contact between the back of thigh and calf into account. The aim of this literature review is to assess whether squats with less knee flexion (half/quarter squats) are safer on the musculoskeletal system than deep squats. A search of relevant scientific publications was conducted between Ma…

Amirthalingam, T, Mavros, Y, Wilson, GC, Clarke, JL, Mitchell, L, and Hackett, DA. Effects of a modified German volume training program on muscular hypertrophy and strength. J Strength Cond Res 31(11): 3109-3119, 2017-German Volume Training (GVT), or the 10 sets method, has been used for decades by weightlifters to increase muscle mass. To date, no study has directly examined the training adaptations after GVT. The purpose of this study was to investigate the effect of a modified GVT intervention on muscular hypertrophy and strength. Nineteen healthy men were randomly assign to 6 weeks of 10 or 5 sets of 10 repet…

Creatine is one of the most popular nutritional ergogenic aids for athletes. Studies have consistently shown that creatine supplementation increases intramuscular creatine concentrations which may help explain the observed improvements in high intensity exercise performance leading to greater training adaptations. In addition to athletic and exercise improvement, research has shown that creatine supplementation may enhance post-exercise recovery, injury prevention, thermoregulation, rehabilitation, and concussion and/or spinal cord neuroprotection. Additionally, a number of clinical applications of creatine suppl…

What determines which motor units are active in a motor task? In the respiratory muscles, motor units are recruited according to their mechanical advantages. We describe a principle of motor unit recruitment by neuromechanical matching due to mechanisms in the spinal cord that sculpt descending drive to motoneurons. This principle may be applicable to movements in nonrespiratory muscles.

BACKGROUND: Few interventions reduce patellar tendinopathy (PT) pain in the short term. Eccentric exercises are painful and have limited effectiveness during the competitive season. Isometric and isotonic muscle contractions may have an immediate effect on PT pain. METHODS: This single-blinded, randomised cross-over study compared immediate and 45 min effects following a bout of isometric and isotonic muscle contractions. Outcome measures were PT pain during the single-leg decline squat (SLDS, 0-10), quadriceps strength on maximal voluntary isometric contraction (MVIC), and measures of corticospinal excitability …

The purpose of this study was to investigate the time course of hypertrophic adaptations in both the upper arm and trunk muscles following high-intensity bench press training. Seven previously untrained young men (aged 25 ± 3 years) performed free-weight bench press training 3 days (Monday, Wednesday and Friday) per week for 24 weeks. Training intensity and volume were set at 75% of one repetition maximum (1-RM) and 30 repetitions (3 sets of 10 repetitions, with 2-3 min of rest between sets), respectively. Muscle thickness (MTH) was measured using B-mode ultrasound at three sites: the biceps and triceps brachii a…

An essential exercise for strength training of the lower limbs is the squat exercise. During this exercise, changes in lumbar lordosis are commonly used to indicate when the descent of the squat should cease, yet the behavior of the lumbar-scarum segments remains unclear. The purpose of this study was to quantify the lumbar-sacrum movements during the back squat, because the movement of the sacrum is influenced by the width of stance, this variable was also investigated. Thirty trained subjects, 18 men with 1 repetition maximum (1RM) squat of 123% (13.9%) of bodyweight and 12 women with 1RM squat of 93% (15.6%), …

BACKGROUND: This study examined low-volume resistance training (RT) in trained participants with and without advanced training methods. METHODS: Trained participants (RT experience 4±3 years) were randomised to groups performing single-set RT: ssRM (N.=21) performing repetitions to self-determined repetition maximum (RM), ssMMF (N.=30) performing repetitions to momentary muscular failure (MMF), and ssRP (N.=28) performing repetitions to self-determined RM using a rest pause (RP) method. Each performed supervised RT twice/week for 10 weeks. Outcomes included maximal isometric strength and body composition using bi…

STUDY DESIGN: Evaluation of a new quantitative imaging technique in a prospective study design. OBJECTIVE: To assess glycosaminoglycan (GAG) content of lumbar intervertebral discs (IVDs) in healthy volunteers with chemical exchange saturation transfer (CEST). SUMMARY OF BACKGROUND DATA: Biochemical alterations of lumbar discs are present before the appearance of morphological changes. GAG loss plays a central role in these degenerative processes. METHODS: Lumbar intervertebral discs of healthy controls (26 women, 22 men; mean age 31 ± 8 years; range: 21-49 years) without lumbar back pain were examined at a 3 Tesl…

PURPOSE: Few studies have assessed neuromuscular fatigue after self-paced locomotor exercise; moreover, none have assessed the degree of supraspinal fatigue. This study assessed central and peripheral fatigue after self-paced exercise of different durations. METHODS: Thirteen well-trained male cyclists completed 4-, 20-, and 40-km simulated time trials (TTs). Pre- and immediately post-TT (<2.5 min), twitch responses from the knee extensors to electrical stimulation of the femoral nerve and transcranial magnetic stimulation of the motor cortex were recorded to assess neuromuscular and corticospinal function. RESUL…

PURPOSE: To assess glycosaminoglycan (GAG) content of lumbar intervertebral discs (IVD) in patients with spondyloarthritis (SpA) using glycosaminoglycan chemical exchange saturation transfer (gagCEST). MATERIALS AND METHODS: Ninety lumbar intervertebral discs of nine patients with SpA and nine age-matched healthy controls (eight patients with ankylosing spondylitis; one patient with spondylitis related to inflammatory bowel disease; mean age: 44.1 ± 14.0 years; range: 27-72 years) were examined with a 3T magnetic resonance imaging (MRI) scanner in this prospective study. The MRI protocol included standard morphol…

The objective of the present study was to determine the instantaneous moment arms of 18 major muscle sub-regions crossing the glenohumeral joint during coronal-plane abduction and sagittal-plane flexion. Muscle moment-arm data for sub-regions of the shoulder musculature during humeral elevation are currently not available. The tendon-excursion method was used to measure instantaneous muscle moment arms in eight entire upper-extremity cadaver specimens. Significant differences in moment arms were reported across sub-regions of the deltoid, pectoralis major, latissimus dorsi, subscapularis, infraspinatus and supras…

The purpose of this study was to examine the extent of activation in various trunk muscles during dynamic weight-training and isometric instability exercises. Sixteen subjects performed squats and deadlifts with 80% 1 repetition maximum (1RM), as well as with body weight as resistance and 2 unstable calisthenic-type exercises (superman and sidebridge). Electromyographic (EMG) activity was measured from the lower abdominals (LA), external obliques (EO), upper lumbar erector spinae (ULES), and lumbar-sacral erector spinae (LSES) muscle groups. Results indicated that the LSES EMG activity during the 80% 1RM squat si…

Tissue engineering of intervertebral discs (IVD) using mesenchymal stem cells (MSCs) induced to differentiate into a disc-cell phenotype has been considered as an alternative treatment for disc degeneration. However, since there is no unique marker characteristic of discs and since hyaline cartilage and immature nucleus pulposus (NP) possess similar macromolecules in their extracellular matrix, it is currently difficult to recognize MSC conversion to a disc cell. This study was performed to compare the proteoglycan to collagen ratio (measured as GAG to hydroxyproline ratio) in the NP of normal disc to that of the…

STUDY DESIGN: A quantitative biomechanical comparison of seven different lumbar spine "stabilization exercises." OBJECTIVES: The purpose of this research was to quantify lumbar spine stability resulting from the muscle activation patterns measured when performing selected stabilization exercises. SUMMARY OF BACKGROUND DATA: Many exercises are termed "stabilization exercises" for the low back; however, limited attempts have been made to quantify spine stability and the resultant tissue loading. Ranking resultant stability together with spinal load is very helpful for guiding clinical decision-making and therapeuti…

STUDY DESIGN: A biomechanical model of the lumbar spine was used to calculate the effects of abdominal muscle coactivation on spinal stability. OBJECTIVES: To estimate the effects of abdominal muscle coactivation on lumbar spine stability, muscle fatigue rate, and lumbar spine compression forces. SUMMARY OF BACKGROUND DATA: The activation of human trunk muscles has been found to involve coactivation of antagonistic muscles, which has not been adequately predicted by biomechanical models. Antagonistic activation of abdominal muscles might produce flexion moments resulting from abdominal pressurization. Qualitative…

Because of the inability of strength tests to accurately discriminate between low back pain patients and healthy subjects, a multifactorial evaluation of low back pain patients is warranted. It is postulated that measurements of endurance, kinematics, postural stability, and coordination, in addition to strength, are necessary to fully document the patients' functional capabilities. This research study was conducted in order to understand the effects of fatigue on the above factors. Twelve healthy male subjects performed a repetitive lifting test in which a submaximal load was lifted at a maximal rate. Knee, hip,…

The lateral backing and postbuckling behaviour of the intact and injured whole human lumbar spine was experimentally studied using six fresh cadaveric specimens. The ligamentous lumbar spine was loaded in axial compression and the lateral rotation of each vertebra was recorded. At the point of the load application, the most superior vertebrae, the specimens were constrained to move in the frontal plane since sagittal plane buckling will not occur due to the lumbar lordosis. The average load required to buckle an intact whole lumbar specimen was 88 N, and significantly decreased with injury. Once the spines had bu…

Creatine is one of the most popular nutritional ergogenic aids for athletes. Studies have consistently shown that creatine supplementation increases intramuscular creatine concentrations which may help explain the observed improvements in high intensity exercise performance leading to greater training adaptations. In addition to athletic and exercise improvement, research has shown that creatine supplementation may enhance post-exercise recovery, injury prevention, thermoregulation, rehabilitation, and concussion and/or spinal cord neuroprotection. Additionally, a number of clinical applications of creatine suppl…

PURPOSE: The purpose of this study was to compare shock attenuation, spatio-temporal and physiological parameters during water immersed (depth: anterior superior iliac spine) aquatic treadmill (ATM) running and land based treadmill (LTM) running matched for speed. METHODS: Six participants completed 15 min running under 2 conditions (LTM and ATM) in a randomised and balanced order, matched for speed. Synchronised tri-axial accelerometers placed at the distal tibia, lumbar region, and forehead were used to identify running dynamics and measure acceleration on impact and its attenuation. Expired respiratory gases a…

The barbell back squat is commonly used by athletes participating in resistance training. The barbell squat is typically performed using standard athletic shoes, or specially designed weightlifting footwear, although there are now a large number of athletes who prefer to squat barefoot or in barefoot-inspired footwear. This study aimed to determine how these footwear influence 3-D kinematics and muscle activation potentials during the barbell back squat. Fourteen experienced male participants completed squats at 70% 1 rep max in each footwear condition. 3-D kinematics from the torso, hip, knee and ankle were meas…

The purpose of this study was to compare muscle activity and kinetics during the back squat and overhead squat performed at 3 relative intensities (60, 75, and 90% 3 repetition maximum). Fourteen subjects (age, 26 ± 7 years; height, 182.5 ± 13.5 cm; body mass, 90.5 ± 17.5 kg) performed each exercise using a within-subjects crossover design. In addition, a selection of trunk isolation exercises were included to provide additional comparisons. Squats were performed on a force platform with electromyographic activity of the anterior deltoid, rectus abdominis (RA), external oblique (EO), erector spinae (ES), gluteus …

The purpose of this study was to examine the effects of a localized muscle endurance resistance training program on total body and regional tissue composition. Seven men and 4 women (aged 23 ± 1 years) were trained with their nondominant leg during 12 weeks, 3 sessions per week. Each session consisted of 1 set of 960-1,200 repetitions (leg press exercise), at 10-30% 1 repetition maximum. Before and after training, body mass, bone mass, bone mineral density (BMD), lean mass, fat mass, and fat percentage were determined by dual-emission x-ray absorptiometry. Energy intakes were registered using a food recall questi…

Squatting is a common strength training exercise used for rehabilitation, fitness training, and in preparation for competition. Knowledge about the loading and the motion of the back during the squat exercise is crucial to avoid overuse or injury. The aim of this study was the measurement and comparison of the kinematics of the lower leg, trunk, and spine during unrestricted and restricted (knees are not allowed beyond toes) squats. A total of 30 subjects performed unrestricted and restricted barbell squats with an extra load of 0, 25, and 50% bodyweight. Motion was tracked using a 12-camera Vicon system. A newly…

The purpose of this study was to compare kinematics and muscle activity between chin-ups and lat-pull down exercises and between muscle groups during the two exercises. Normalized electromyography (EMG) of biceps brachii (BB), triceps brachii (TB), pectoralis major (PM), latissimus dorsi (LD), rectus abdominus (RA), and erector spinae (ES) and kinematics of back, shoulder, and seventh cervical vertebrae (C7) was analysed during chin-ups and lat-pull down exercises. Normalized EMG of BB and ES and kinematics of shoulder and C7 for chin-ups were greater than lat-pull down exercises during the concentric phase (p < …

STUDY DESIGN: Randomized controlled trial. OBJECTIVE: To compare the effects of full range of motion (ROM) and limited ROM isolated lumbar extension exercise upon full ROM lumbar extension strength, ROM, perceived pain, and disability. SUMMARY OF BACKGROUND DATA: Limited ROM is common in chronic low back pain as is lumbar extensor deconditioning. Limited ROM exercise is a common prescription but is yet to be empirically tested. METHODS: Males (n = 21) and females (n = 17) with nonspecific chronic low back pain were initially recruited. Participants were randomized to either a full ROM (FullROM) or limited ROM (Li…

PURPOSE: Strength athletes often employ the deadlift in their training or rehabilitation regimens. The purpose of this study was to compare muscle activity between sumo and conventional style deadlifts, and between belt and no-belt conditions. METHODS: Six cameras collected 60-Hz video data and 960-Hz electromyographic data from 13 collegiate football players who performed sumo and conventional deadlifts with and without a lifting belt, employing a 12-RM intensity. Variables measured were knee angles and EMG measurements from 16 muscles. Muscle activity were averaged and compared within three 30-degree knee angle…

The term “stability,” as used in the field of biomechanics, remains undefined in many clinical cases. This fact can impede the design of therapies intended to enhance joint stability. In fact, Fritz et al, in a review on lumbar instability, concluded that, “At present, much controversy exists regarding the proper definition of the condition, the best diagnostic methods, and the most efficacious treatment approaches.” Some progress has been made in the biomechanics field toward the formulation and implementation of stability in musculoskeletal linkages and joints. The purpose of this review is to synthesize and in…

The purpose of this study was to examine the effectiveness of weight-belts during multiple repetitions of the parallel back squat exercise. Five subjects were filmed (50 fps) as they performed eight consecutive trials at each of two weight-belt conditions [with belt = WB, without belt = WOB] in random order at their eight-repetition maximum effort. Other parameters examined were ground reaction forces, intra-abdominal pressure (IAP), and mean electromyography (mEMG) for the external oblique (EO), erector spinae (ES), vastus lateralis (VL), and bicep femoris (BF) muscles. All parameters were collected and interfac…

The purpose of this study was to determine whether abdominal belts such as those prescribed to industrial workers reduced trunk muscle activity and/or increased intra-abdominal pressure (IAP). In this study, six subjects lifted loads (72.7 to 90.9 kg) both with and without wearing a weightlifter belt. In addition, further trial conditions required that subjects lifted both with the breath held or continuously expiring on lifting effort. Dynamic hand loads were recorded together with intra-abdominal pressure (IAP) and abdominal, intercostal and low back EMG. Every subject demonstrated an increase in IAP when weari…

OBJECTIVES: Chronic abdominal wall pain may be caused by Anterior Cutaneous Nerve Entrapment Syndrome (ACNES). The diagnostic cornerstone is a characteristic physical examination including a localized area of altered skin sensation covering a point of maximum pain. Recently, the Scratch Collapse Test (SCT) emerged as a sensitive noninvasive test for ACNES. However, this test relies on manual force application, which introduces potential examiner bias and raises concerns regarding its objectivity. Therefore, we modified the Empty Can Test, used to detect rotator cuff injuries, into the Empty Can Scratch Test (ECST…

Abstract: Many in the scientific community have been debating the extent to which the spine can adapt. While it is widely accepted that vertebral bones can adapt and become stronger/denser with appropriately dosed loading, there are still many unanswered questions regarding intervertebral discs (IVDs). Recently, some are claiming that IVDs can adapt to stress under load and become stronger and more resilient over time based on the findings from a recent study “Imaging of exercise-induced spinal remodeling in elite rowers” by Frenken et al 2022 in the Journal of Science and Medicine in Sport. The Frenken paper inv…

BACKGROUND: Inspite of common lifting advice to maintain a lordotic posture, there is debate regarding optimal lumbar spine posture during lifting. To date, the influence of lumbar posture on trunk muscle recruitment, strength and efficiency during high intensity lifting has not been fully explored. RESEARCH QUESTION: How do differences in lumbar posture influence trunk extensor strength (moment), trunk muscle activity, and neuromuscular efficiency during maximal lifting? METHODS: Twenty-six healthy participants adopted three lumbar postures (maximal extension (lordotic), mid-range (flat-back), and fully flexed) …

The purpose of this study was to systematically review the literature as to the effects of performing exercise with a full versus partial range of motion (ROM) during dynamic, longitudinal resistance training (RT) programs on changes in muscle hypertrophy. Based on the available literature, we aimed to draw evidence-based recommendations for RT prescription. Six studies were identified as meeting inclusion criteria: four of these studies involved RT for the lower limbs while the other two focused on the upper extremities. The total combined sample of the studies was n = 135, which comprised 127 men and 8 women. T…

KEY POINTS: Previous studies have indicated that several weeks of strength training is sufficient to elicit significant adaptations in the neural drive sent to the muscles. There are few data, however, on the changes elicited by strength training in the recruitment and rate coding of motor units during voluntary contractions. We show for the first time that the discharge characteristics of motor units in the tibialis anterior muscle tracked across the intervention are changed by 4 weeks of strength training with isometric voluntary contractions. The specific adaptations included significant increases in motor uni…

CONTEXT: Research on d-aspartic acid (DAA) has demonstrated increases in total testosterone levels in untrained men, however research in resistance-trained men demonstrated no changes, and reductions in testosterone levels. The long-term consequences of DAA in a resistance trained population are currently unknown. OBJECTIVE: To evaluate the effectiveness of DAA to alter basal testosterone levels over 3 months of resistance training in resistance-trained men. DESIGN: Randomised, double-blind, placebo controlled trial in healthy resistance-trained men, aged 18-36, had been performing regular resistance training exe…

Background: Considerable attention has recently focused on dietary protein's role in the mature skeleton, prompted partly by an interest in nonpharmacologic approaches to maintain skeletal health in adult life.Objective: The aim was to conduct a systematic review and meta-analysis evaluating the effects of dietary protein intake alone and with calcium with or without vitamin D (Ca±D) on bone health measures in adults.Design: Searches across 5 databases were conducted through October 2016 including randomized controlled trials (RCTs) and prospective cohort studies examining 1) the effects of "high versus low" prot…

BACKGROUND: Creatine (Cr) supplementation associated with resistance training produces greater muscular strength improvements in the upper compared with the lower body; however, no study has investigated if such region-specific results are seen with gains in muscle mass. AIM: We aimed to evaluate the effect of Cr supplementation in combination with resistance training on lean soft tissue changes in the upper and lower limbs and trunk in resistance-trained young adult men. METHODS: In a randomized, double-blind and placebo-controlled design, 43 resistance-trained men (22.7 ± 3.0 years, 72.9 ± 8.7 kg, 177.9 ± 5.7 c…

Glassbrook, DJ, Helms, ER, Brown, SR, and Storey, AG. A review of the biomechanical differences between the high-bar and low-bar back-squat. J Strength Cond Res 31(9): 2618-2634, 2017-The back-squat is a common exercise in strength and conditioning for a variety of sports. It is widely regarded as a fundamental movement to increase and measure lower-body and trunk function, as well as an effective injury rehabilitation exercise. There are typically 2 different bar positions used when performing the back-squat: the traditional "high-bar" back-squat (HBBS) and the "low-bar" back-squat (LBBS). Different movement str…

Resistance exercises can be considered to be multi-joint (MJ) or single-joint (SJ) in nature. Many strength coaches, trainers, and trainees believe that adding SJ exercises to a resistance training (RT) program may be required to optimize muscular size and strength. However, given that lack of time is a frequently cited barrier to exercise adoption, the time commitment resulting from these recommendations may not be convenient for many people. Therefore, it is important to find strategies that reduce the time commitment without negatively affecting results. The aim of this review was to analyze and discuss the pr…

Abstract The present study aimed to elucidate the effect of core training on trunk flexor musculature in athletes. Twenty-eight collegiate male soccer players were randomly assigned to three groups: a training group that performed core exercises with wheeled platforms (WP), a training group that performed body mass-based core exercise (BME), and a control group that did not perform core exercise training (CON). WP and BME trained twice a week for 10 weeks. The WP performed 8–14 exercises with wheeled platforms. BME conducted four core exercises to failure. Before and after the intervention, trunk segment lean bod…

PURPOSE OF REVIEW: Mechanisms leading to anterior cruciate ligament (ACL) injury have been identified, yet re-injury or a secondary injury persists in the athletic population. The purpose of this review is to identify risk factors associated with ACL injury and investigate programs to prevent injury. RECENT FINDINGS: Faulty mechanics during dynamic movement that cause excessive valgus force at the knee increases the risk of ACL injury. Faulty mechanics may be a result of lateral displacement of the trunk, unequal limb loading, and lack of control to avoid the valgus knee position. Altered movements that place the…

The aim of this study was to investigate the possible kinematic and muscular activity changes with maximal loading during squat maneuver. Fourteen healthy male individuals, who were experienced at performing squats, participated in this study. Each subject performed squats with 80%, 90%, and 100% of the previously established 1 repetition maximum (1RM). Electromyographic (EMG) activities were measured for the vastus lateralis, vastus medialis, rectus femoris, semitendinosus, biceps femoris, gluteus maximus, and erector spinae by using an 8-channel dual-mode portable EMG and physiological signal data acquisition s…

BACKGROUND: The main purpose of this study was to analyze the behavior of the geometric curvature of the lumbar spine during restricted and unrestricted squats, using a novel investigative method. The rationale for our hypothesis is that the lumbar curvature has different patterns at different spine levels depending on the squat technique used. METHODS: Spine motion was collected via stereo-photogrammetric analysis in nineteen participants (11 males, 8 females). The reconstructed spine points at the upright neutral position and at the deepest position of the squat exercise were projected onto the sagittal plane o…

UNLABELLED: Despite an intuitive relationship between technique and both running economy (RE) and performance, and the diverse techniques used by runners to achieve forward locomotion, the objective importance of overall technique and the key components therein remain to be elucidated. PURPOSE: This study aimed to determine the relationship between individual and combined kinematic measures of technique with both RE and performance. METHODS: Ninety-seven endurance runners (47 females) of diverse competitive standards performed a discontinuous protocol of incremental treadmill running (4-min stages, 1-km·h increme…

Dance - as a ritual, therapy, and leisure activity - has been known for thousands of years. Today, dance is increasingly used as therapy for cognitive and neurological disorders such as dementia and Parkinson's disease. Surprisingly, the effects of dance training on the healthy young brain are not well understood despite the necessity of such information for planning successful clinical interventions. Therefore, this study examined actively performing, expert-level trained college students as a model of long-term exposure to dance training. To study the long-term effects of dance training on the human brain, we c…

OBJECTIVE: This study aims to explore the clinical applicability and relevance of glycosaminoglycan Chemical Exchange Saturation Transfer (gagCEST) for intervertebral disc. METHODS: 25 subjects ranging in age from 24 yrs to 74 yrs were enrolled. gagCEST was acquired using a single-slice TSE sequence on a 3T. Saturation used a continuous rectangular RF pulse with B1=0.8 µT and a fixed duration time=1100 ms. Sagittal image was obtained firstly without saturation pulse, and then saturated images were acquired at 52 offsets ranging from ±0.125 to ±7 parts per million (ppm). MR T2 relaxivity map was acquired at the id…

Using exercise to enhance physical fitness may have little impact on performers' movement patterns beyond the gym environment. This study examined the fitness and movement adaptations exhibited by firefighters in response to 2 training methodologies. Fifty-two firefighters were assigned to a movement-guided fitness (MOV), conventional fitness (FIT), or control (CON) group. Before and after 12 weeks of training, participants performed a fitness evaluation and laboratory-based test. Three-dimensional lumbar spine and frontal plane knee kinematics were quantified. Five whole-body tasks not included in the interventi…

BACKGROUND: Despite the importance of body composition in athletes, reference sex- and sport-specific body composition data are lacking. We aim to develop reference values for body composition and anthropometric measurements in athletes. METHODS: Body weight and height were measured in 898 athletes (264 female, 634 male), anthropometric variables were assessed in 798 athletes (240 female and 558 male), and in 481 athletes (142 female and 339 male) with dual-energy X-ray absorptiometry (DXA). A total of 21 different sports were represented. Reference percentiles (5th, 25th, 50th, 75th, and 95th) were calculated fo…

BACKGROUND: IgE-mediated cow's milk-allergic (IgE-CMA) patients provide a valuable model for studying the relationship between dairy intake and bone mineral density (BMD) because they are unable to consume even minor amounts of dairy foods. OBJECTIVE: To determine the effects of dairy restriction on BMD in young adult IgE-CMA patients. METHODS: A prospective observational study was conducted from July 2012 to June 2013 at the Allergy unit of the Assaf-Harofeh Medical Center. Densitometric measurements of postpubertal patients diagnosed with IgE-CMA (group I, n = 33) were compared with those of volunteers matched …

The purpose of this study was to investigate the relationship between hamstring passive stiffness and extensibility in asymptomatic individuals with the reporting of low back pain during 2-h prolonged standing. Twenty healthy participants with no history of low back pain (mean±SD, age 22.6±2.7 years, height 1.74±0.09 m, weight 76.2±14.8 kg). Low back pain (VAS score; mm) was continuously monitored during 2-h prolonged standing. Hamstring extensibility, passive stiffness, and stretch tolerance were measured before and after prolonged standing using an instrumented straight leg raise (iSLR). Ten participants report…

The purpose of this article was to review a series of studies (n = 18) where muscle activation in the free barbell back squat was measured and discussed. The loaded barbell squat is widely used and central to many strength training programs. It is a functional and safe exercise that is obviously transferable to many movements in sports and life. Hence, a large and growing body of research has been published on various aspects of the squat. Training studies have measured the impact of barbell squat loading schemes on selected training adaptations including maximal strength and power changes in the squat. Squat exe…

The purpose of this study was to validate a higher degree of foot segment angle by wearing the weightlifting (WL) shoes and to determine the kinematic differences between WL shoes and running shoes during the barbell back squat. College-aged individuals volunteered to participate in this study (N = 25). After warm-up, subjects performed 60% of 1RM barbell back squat. Reflective markers were placed on lower extremity joints and end of the bar to create segments to analyze kinematics of the barbell back squat from a 2-dimensional view. Three separate repeated measure analyses of variance were used at p = 0.05. Resu…

BACKGROUND: The COMT enzyme metabolizes catecholamines and thus modulates adrenergic, noradrenergic and dopaminergic signaling. A functional polymorphism in the gene encoding this enzyme, i.e. the COMT Val158Met SNP that reduces enzyme activity, has previously been linked to pain sensitivity. METHODS: We examined if the COMT Val158Met SNP could contribute to discogenic subacute low back pain and sciatica by comparing the frequency of the Val158Met genotypes of degenerative disc disease patients with healthy controls. Moreover, we examined if this SNP could predict the clinical outcome, i.e. the progression of pai…

In this overview, new and existent material on the organization and composition of the thoracolumbar fascia (TLF) will be evaluated in respect to its anatomy, innervation biomechanics and clinical relevance. The integration of the passive connective tissues of the TLF and active muscular structures surrounding this structure are discussed, and the relevance of their mutual interactions in relation to low back and pelvic pain reviewed. The TLF is a girdling structure consisting of several aponeurotic and fascial layers that separates the paraspinal muscles from the muscles of the posterior abdominal wall. The supe…

This study compared a conventional pull-up and chin-up with a rotational exercise using Perfect·Pullup™ twisting handles. Twenty-one men (24.9 ± 2.4 years) and 4 women (23.5 ± 1 years) volunteered to participate. Electromyographic (EMG) signals were collected with DE-3.1 double-differential surface electrodes at a sampling frequency of 1,000 Hz. The EMG signals were normalized to peak activity in the maximum voluntary isometric contraction (MVIC) trial and expressed as a percentage. Motion analysis data of the elbow were obtained using Vicon Nexus software. One-factor repeated measures analysis of variance examin…

The aim of this review was to provide of the current knowledge in pathophysiology, diagnosis and management of spondylolysis based on the authors' experience and the pertinent medical literature. Spondylolysis represents a weakness or stress fracture in one of the bony bridges that connect the upper with the lower facet joints of the vertebra. It is the most common cause of low back pain in young athletes. One-half of all paediatric and adolescent back pain in athletic patients is related to various disturbances in the posterior elements including spondylolysis. The most common clinical presentation of spondyloly…

The relationship between trunk and spine deformity has yet not been well defined. The purpose of this study was to identify the relationship between clinical (contourometric) and radiographic methods of scoliotic deformity evaluation. Our second objective was to create mathematical formulas for calculating radiographic parameters based on defined correlations of multiple parameters. We did a study of 136 preoperatively analysed patients with idiopathic scoliosis. Altogether, 189 lateral curvatures were assessed. Based on Lenke's classification, curves were divided into three groups: a thoracic, a thoracolumbar an…

The purpose of this study was to compare the passive mechanical properties and titin isoform sizes of the multifidus, longissimus, and iliocostalis muscles. Given our knowledge of each muscle's architecture and the multifidus' operating range, we hypothesized that multifidus would have higher elastic modulus with corresponding smaller titin isoforms compared to longissimus or iliocostalis muscles. Single-fiber and fiber-bundle material properties were derived from passive stress-strain tests of excised biopsies (n=47). Titin isoform sizes were quantified via sodium dodecyl sulfate-vertical agarose gel electrophor…

The aim of the present study was to investigate the effect of experimental and chronic neck-shoulder pain on the magnitude of cycle-to-cycle variability of task timing, kinematics and muscle activation during repetitive arm movement performed for 3 or 5 min. In an experimental part, acute muscle pain was induced in healthy subjects by intramuscular injection of hypertonic saline in trapezius (n = 10) and infraspinatus (n = 10) muscles. In a clinical part, workers with (n = 12) and without (n = 6) chronic neck-shoulder pain were compared. Cycle-to-cycle standard deviations of task duration, arm and trunk movement …

Ashwagandha (root of Withania somnifera) has been used for many purposes, it is mainly considered a tonic in traditional Ayurvedic medicine. This review focuses on the effects of compounds isolated from Ashwagandha on dementia models and on the spinal cord injury model. Our study demonstrated that the active constituents, withanolide A, withanoside IV, and withanoside VI, restored presynapses and postsynapses, in addition to both axons and dendrites in cortical neurons after Abeta(25-35)-induced injury. In vivo, oral withanolide A, withanoside IV, and withanoside VI (10 micromol/kg/day for 12 days) improved Abeta…

Two major theories proposed to explain the effect of pain on muscle activity are the Vicious Cycle Theory and the Pain Adaptation Model. Comprehensive reviews demonstrate conflicting or limited evidence in support of a critical aspect of the Vicious Cycle Theory, namely that pain leads to increased muscle activity. The Pain Adaptation Model proposes that changes in muscle activity limit movement and thereby protect the sensorimotor system from further injury. This model is generally considered the most appropriate explanation of the effect of pain on muscle function. Although there is much literature consistent w…

If exercises are performed to increase muscle strength on one side of the body, voluntary strength can increase on the contralateral side. This effect, termed the contralateral strength training effect, is usually measured in homologous muscles. Although known for over a century, most studies have not been designed well enough to show a definitive transfer of strength that could not be explained by factors such as familiarity with the testing. However, an updated meta-analysis of 16 properly controlled studies (range 15-48 training sessions) shows that the size of the contralateral strength training effect is app…

Interlimb coordination is critically important during bipedal locomotion and often must be adapted to account for varying environmental circumstances. Here we studied adaptation of human interlimb coordination using a split-belt treadmill, where the legs can be made to move at different speeds. Human adults, infants, and spinal cats can alter walking patterns on a split-belt treadmill by prolonging stance and shortening swing on the slower limb and vice versa on the faster limb. It is not known whether other locomotor parameters change or if there is a capacity for storage of a new motor pattern after training. W…

OBJECTIVE: For many individuals with chronic low back pain (CLBP), there is no identifiable cause. In other idiopathic chronic pain conditions, sensory testing and functional magnetic resonance imaging (fMRI) have identified the occurrence of generalized increased pain sensitivity, hyperalgesia, and altered brain processing, suggesting central augmentation of pain processing in such conditions. We compared the results of both of these methods as applied to patients with idiopathic CLBP (n = 11), patients with widespread pain (fibromyalgia; n = 16), and healthy control subjects (n = 11). METHODS: Patients with CLB…

UNLABELLED: Some recommendations suggest keeping the shank as vertical as possible during the barbell squat, thus keeping the knees from moving past the toes. This study examined joint kinetics occurring when forward displacement of the knees is restricted vs. when such movement is not restricted. Seven weight-trained men (mean +/- SD; age = 27.9 +/- 5.2 years) were videotaped while performing 2 variations of parallel barbell squats (barbell load = body weight). Either the knees were permitted to move anteriorly past the toes (unrestricted) or a wooden barrier prevented the knees from moving anteriorly past the t…

STUDY DESIGN: A multifactorial cross-sectional nonexperimental design. OBJECTIVES: To collectively investigate the association among 17 mechanical factors and occurrence of low back pain (LBP). BACKGROUND: Several physical characteristics, based on assumptions, clinical findings, and scientific experiments, have been associated with the development of LBP Controversy exists regarding the degree of association between some of these physical characteristics and LBP. Information regarding the degree of association of each factor to LBP is needed for effective prevention and appropriate treatment strategies. METHODS …

The purpose of this study was to investigate the relationship between running economy (RE) and lower body flexibility. Thirty-four international-standard male distance runners (mean +/- s, age 27 +/- 5 years; body mass 64.9 +/- 4.2 kg; VO(2)max 72.8 +/- 3.7 ml x kg(-1) x min(-1)) gave written consent to participate in this study. The subjects performed an incremental treadmill test for the assessment of RE, lactate threshold and VO(2)max, and the sit-and-reach test was used to assess their general lower body and trunk flexibility. Running speeds below the lactate threshold were used to explore the relationship be…

PURPOSE: The purpose of this study was to quantify biomechanical parameters employing two-dimensional (2-D) and three-dimensional (3-D) analyses while performing the squat with varying stance widths. METHODS: Two 60-Hz cameras recorded 39 lifters during a national powerlifting championship. Stance width was normalized by shoulder width (SW), and three stance groups were defined: 1) narrow stance squat (NS), 107 +/- 10% SW; 2) medium stance squat (MS), 142 +/- 12% SW; and 3) wide stance squat (WS), 169 +/- 12% SW. RESULTS: Most biomechanical differences among the three stance groups and between 2-D and 3-D analyse…

Current knowledge of the physiological, biomechanical, and sensory effects of the cycle to run transition in the Olympic triathlon (1.5 km, 10 km, 40 km) is reviewed and implications for the training of junior and elite triathletes are discussed. Triathlon running elicits hyperventilation, increased heart rate, decreased pulmonary compliance, and exercise induced hypoxaemia. This may be due to exercise intensity, ventilatory muscle fatigue, dehydration, muscle fibre damage, a shift in metabolism towards fat oxidation, and depleted glycogen stores after a 40 km cycle. The energy cost (CR) of running during the cyc…

The increased intra-abdominal pressure (IAP) commonly observed when the spine is loaded during physical activities is hypothesized to increase lumbar spine stability. The mechanical stability of the lumbar spine is an important consideration in low back injury prevention and rehabilitation strategies. This study examined the effects of raised IAP and an abdominal belt on lumbar spine stability. Two hypotheses were tested: (1) An increase in IAP leads to increased lumbar spine stability, (2) Wearing an abdominal belt increases spine stability. Ten volunteers were placed in a semi-seated position in a jig that rest…

Currently, intra-abdominal pressure (IAP) is thought to provide stability to the lumbar spine but the exact principles have yet to be specified. A simplified physical model was constructed and theoretical calculations performed to illustrate a possible intra-abdominal pressure mechanism for stabilizing the spine. The model consisted of an inverted pendulum with linear springs representing abdominal and erector spinae muscle groups. The IAP force was simulated with a pneumatic piston activated with compressed air. The critical load of the model was calculated theoretically based on the minimum potential energy pri…

As men age, their serum testosterone concentrations decrease, as do their bone densities. Because bone density is also low in hypogonadal men, we hypothesized that increasing the serum testosterone concentrations of men over 65 yr to those found in young men would increase their bone densities. We randomized 108 men over 65 yr of age to wear either a testosterone patch or a placebo patch double blindly for 36 months. We measured bone mineral density by dual energy x-ray absorptiometry before and during treatment. Ninety-six men completed the entire 36-month protocol. The mean serum testosterone concentration in t…

This study examined hypertrophy after head extension resistance training to assess which muscles of the complicated cervical neuromuscular system were used in this activity. We also determined if conventional resistance exercises, which are likely to evoke isometric action of the neck, induce generalized hypertrophy of the cervical muscle. Twenty-two active college students were studied. [mean (SE) age, weight and height: 21 (1) years, 71 (4) kg and 173 (3) cm, respectively]. Subjects were assigned to one of three groups: RESX (head extension exercise and other resistance exercises), RES (resistance exercises wit…

The purpose of this study was to investigate whether the maneuver of altering the angle of pelvic tilt when standing is effective in changing the angle of lumbar lordosis. The importance of the study was to establish a scientific basis for a common clinical assumption. Pelvic tilt and lumbar lordosis were measured during three conditions: with subjects in a normal standing posture, with subjects assuming a maximal anterior pelvic tilt posture, and with subject assuming a maximal posterior pelvic tilt posture. Measurements of pelvic tilt and lumbar lordosis were obtained using a television/computer system that obt…

The purpose of this study was to examine the association between nine measures of limb and trunk flexibility and running economy. Within a week prior to running economy assessment, and after 10 min of jogging at 3.13 m.s-1, 19 well-trained male sub-elite distance runners underwent two complete sets of lower limb and trunk flexibility assessments. Runners then completed two 10-min running economy assessment sessions on consecutive days at 4.13 m.s-1 following two 30-min sessions of treadmill accommodation at 4.13 m.s-1. Intraclass correlation coefficients indicated that the repeated flexibility measurements were h…

The purpose of this study was to examine the relationship of bone mineral density (BMD) to muscular strength in highly trained young male athletes in order to gain insights concerning the influence of heavy resistance training on BMD. Twenty-five elite junior weightlifters (age, 17.4 +/- 1.4 yr) and 11 age-matched controls (16.9 +/- 1.1 yr) volunteered for this investigation. Measurements of BMD (g.cm-2) utilizing dual energy x-ray absorptiometry were obtained for the lumbar spine (L2-4) and the proximal femur (neck; trochanter, Ward's triangle). The BMD values for the junior lifters were found to be significantl…

The reaction moments at the knee, hip, and L4/L5 joints, and the compressive and shearing forces on L4/L5 are documented in powerlifters competing in a national powerlifting championship. Analyses were made of 13 female and 44 male competitors. The joint moments and forces were estimated from a linked segment model (WATBAK) that incorporated functional low back extensor musculature with a moment arm of 6 cm and a line action that was oriented 5 degrees posteriorly to the L4/L5 compression axis. This oblique orientation of the extensor muscles reduced the anterior shearing load on the vertebral motion unit. Averag…

The purpose of this study was to examine the effectiveness of weight-belts during the performance of the parallel squat exercise. Six subjects were filmed (40 fps) as they performed three trials at each of three belt conditions (NB, none; LB, light; HB, heavy) in random order and three load conditions (70, 80, 90% 1RM (one repetition maximum] in increasing order. The parameters examined were collected and interfaced to a computer via an analog-to-digital (A/D) converter: ground reaction forces, intra-abdominal pressure (IAP), and EMG for the rectus abdominus (RA), external oblique (EO), and erector spinae (ES) mu…