Variability of unilateral and bilateral isometric muscle strength of lower extremities extensors in young females and males.

BACKGROUND: The muscle strength of the lower extremity extensors can be evaluated in the closed kinetic chain (CKC) during unilateral or bilateral conditions. Factors such as the mass and length of the muscle, joint angle, type of contraction, and gender influence the magnitude of the muscle strength. The aim of this study was to compare the isometric strength of lower extremity extensors between the different knee extension angles (KEs) as well as between bilateral and unilateral conditions. METHODS: Nineteen female students (age: 20.2 ± 0.6 years) and nineteen male students (age: 20.3 ± 0.7 years) participated in the study. The muscle strength was evaluated in CKC using the strain gauge dynamometer. The analysis included values of the maximum muscle strength normalized to body mass (MS/BM) for the six KEs of 80°, 70°, 60°, 50°, 40° and 30°. RESULTS: A significant main effect in the MS/BM values for the angle factor (p < 0.001) and condition factor (p < 0.001) was found. Moreover, there was a non-significant interaction effect between the angle factor and gender factor (p = 0.476) as well as between the condition factor and gender factor (p = 0.770). Comparisons showed significant differences in the MS/BM values between the six KEs (p < 0.001). Furthermore, significantly lower MS/BM values for bilateral conditions than unilateral conditions at the 30° KE were observed (p < 0.001). CONCLUSION: The decrease in KE by 10° significantly increased the muscle strength of the lower extremity extensors. Gender did not affect the change in MS/BM values with the change in KE and conditions. Findings also revealed significant bilateral deficit, i.e., significantly a lower summed muscle strength during bilateral conditions than unilateral conditions. The study emphasized the importance of selecting the 30° KE as the optimal angle to assess the maximum strength developed in CKC.

Influence of School Backpack Load as a Variable Affecting Gait Kinematics among Seven-Year-Old Children.

This article investigates schoolchildren's ability to carry an additional load using a backpack (BP). According to scientific research, there is no precise limit to the maximum backpack load, which varies from 10% to 15% of body weight (BW). The purpose of this study was, therefore, to evaluate the influence of an additional external load carried using a backpack on gait kinematics among seven-year-old children in Poland, including assessment of the gender differences. The study was conducted among 26 (13 boys and 13 girls) primary school children aged seven years. The children walked at their preferred speed, under four conditions: with no load (0% BW) and with 10%, 15% and 20% BW. Spatiotemporal parameters were measured using the 2 m Footscan® platform system and photocell Sectro timing system. The children walked more slowly under an additional load. Their step length and single support time decreased. Their base of support, step time and double support time increased. There was no significant effect on their stride length or gait cycle time. The gait kinematic changes were most evident between 10% BW and greater loading. The results highlight how children's gait is affected by carrying additional external loads, which should not exceed 10% BW. That limit is appropriate for both genders.

Relationship between Isokinetic Knee Strength and Speed, Agility, and Explosive Power in Elite Soccer Players.

The aim of this study was to determine the relationship between the isokinetic characteristics of knee extensors and flexors with selected motor abilities: Speed, agility, and explosive power of lower extremities of professional football players in the preparation period of a yearly training cycle. Twenty-one players (age: 24.5 ± 3.9 years; body mass: 76.7 ± 4.7 kg and body height: 183.5 ± 5.5 cm) playing in the highest Polish soccer league participated in the study. The isokinetic concentric torque of the knee extensors and flexors was measured at 300°/s, 180°/s, and 60°/s velocities. Sprint performance was assessed in the 30 m sprint test (standing start). The forward, lateral, and backward movements were assessed using the T-Test of agility. Explosive power was quantified by performing the squat jump (SJ) and countermovement (CMJ), using the force platform. Due to sport-specific demands of soccer activities measured in this experiment, the relationships between peak torque (PT) and the 30 m sprint, T-Test of agility, and power of vertical jumps (SJ and CMJ) were low or medium at speeds of 60°/s and 300°/s. One of the main reasons for the lack of high dependence of the above-mentioned factors are that the measurements were performed during the initial training period where the level of individual abilities is at a low level. Additionally, this experiment may also indicate that the measurement of isokinetic knee flexion and extension peak is effective when performed at the correct angular velocity in relation to the evaluation of the intended motion structure.

Lower Extremities Strength Differences in Female Volleyball Players With Stage 1 Patellar Tendinopathy.

ABSTRACT: Kabacinski, J, Murawa, M, Fryzowicz, A, Gorwa, J, and Dworak, LB. Lower extremities strength differences in female volleyball players with stage 1 patellar tendinopathy. J Strength Cond Res 36(8): 2230-2235, 2022-The main purpose of the study was to compare the muscle strength between the involved knee (IK) and uninvolved knee (UK) in 12 female volleyball players with stage 1 chronic patellar tendinopathy. Evaluation included the isometric maximal strength to body mass (MS/BM) of the lower extremities extensors for unilateral and bilateral conditions, concentric isokinetic peak torque to body mass (PT/BM) of the hamstrings and quadriceps at 60°·s -1 and 180°·s -1 , IK to UK extensors maximal strength ratio (SR), IK to UK hamstrings (or quadriceps) peak torque ratio (TR), and hamstrings to quadriceps peak TR (H/Q). The results indicated a significantly lower unilateral and bilateral MS/BM of lower extremities extensors for IK than UK ( p < 0.001). However, there were no significant differences in SR variable between the unilateral condition and bilateral condition ( p = 0.448). Only at the 60°·s -1 velocity, significantly lower quadriceps PT/BM for IK compared with the UK ( p < 0.001) and the control group ( p < 0.001) were observed. Torque ratio related to the quadriceps group was significantly lower at 60°·s -1 than 180°·s -1 ( p = 0.004). Furthermore, significantly higher H/Q for IK compared with UK ( p < 0.001) and control group ( p = 0.008) only at 60°·s -1 was found. These findings show a significant isometric strength asymmetry for both unilateral and bilateral conditions and a significant concentric strength asymmetry at the low velocity. This study suggests strengthening the weaker quadriceps group and balancing the strength between hamstrings and quadriceps within the knee with patellar tendinopathy.

Socioeconomic Risk Factors of Poor Nutritional Status in Polish Elderly Population: The Results of PolSenior2 Study.

Poor nutritional status (PNS) threatens successful aging. Identifying potentially modifiable predictors of PNS is essential for elaborating a preventive strategy for the population at risk. To assess the prevalence of PNS in the Polish elderly population and analyze its socioeconomic correlates based on the data from the nationwide PolSenior2 project. Special emphasis was put on potentially modifiable factors among the identified PNS predictors. Nutritional status was assessed in 5698 community-dwelling older adults with the Mini Nutritional Assessment-Short Form. We evaluated the effect of age, sex, level of education, marital status, place of residence, subjective loneliness, and self-reported poverty on the nutritional status of the studied subjects. PNS was found in 25.3% of studied subjects (27.7% women and 21.9% men; p < 0.001). Female sex, older age, unmarried status (in men), subjective loneliness, and self-reported poverty were independent correlates of PNS. The two last above-mentioned predictors were identified as potentially modifiable. Based on our results, we recommend preventive interventions (e.g., performing regular screening), particularly in unmarried (men), poorly educated individuals, self-reporting poverty, complaining of loneliness, and the oldest old. PNS preventive strategies should include social support (both emotional and instrumental) to reduce the effect of poverty and subjective loneliness.

Isokinetic and Isometric Assessment of the Knee Joint Extensors and Flexors of Professional Volleyball Players.

PURPOSE: The main objective of this study was to evaluate the level of muscle strength by using isokinetic and isometric measurements-more specifically, the force ratio between the knee flexors and extensors (values of the torques). METHODS: An experimental group of elite volleyball players (n = 14) were compared to a control group (n = 14) of healthy non-athletes of comparable ages. Torque measurements were obtained under three concentric conditions (angular velocities of 60 °/s, 180 °/s, and 300 °/s) and one static condition by utilizing the Biodex System 3. RESULTS: In all trials, the volleyball players achieved significantly higher peak torque (PT) values for both the extensors and flexors (p < 0.05) than those of the control group. However, the strength ratio of the flexors and extensors (H/Q) in the experimental group was only 83% of the standard reported in the literature. The most developed and dominating muscles in the knee joints of the volleyball players were the extensors, which accounted for the low strength ratio and dynamic instability of this joint. CONCLUSION: Based on a proper assessment of the strength ratio of the knee flexors and extensors, properly selected and implemented resistance training can improve the maximum strength and power production and reduce the incidence of injuries in volleyball.

Constraints on variation of weight-shifting by foot during walking in adolescents with valgus alignment of hallux.

PURPOSE: Etiology of hallux valgus (HV) remains unclear and effective treatments and prophylaxis for this condition are lacking and conclusions of researches concerning HV are inconsistent. Recognition of the function-structure interrelation in foot at the early stage of valgus alignment of first metatarsophalangeus joint (1stMTPJ) would help explain the etiology of HV. METHODS: The frequency of weight-shifting patterns during walking and the body mass index (BMI) were assessed relative to goniometric measurements of the 1stMTPJ angle in adolescents. Weight-shifting patterns were identified with a plantar pressure analysis, performed with the Gaitline- Maxline Distance method. RESULTS: As the 1stMTPJ angle widened, the frequency distributions of identified weight-shifting patterns became increasingly lopsided, due to the favoring or disfavoring of one pattern at the expense of the other. The two sexes showed opposite trends in the weight-shifting patterns that were favored/disfavored, relative to participants with a 0º 1stMTPJ angle. The clear predominance of a central-shift pattern, at the expense of a medial-shift, occurred with the largest (20º) 1stMTPJ angle among girls. Additionally, the BMI distributions associated with 1stMTPJ angle characteristics showed opposite trends between the sexes. CONCLUSIONS: Valgus alignment of 1stMTPJ among adolescents were associated with limitations in weight-shifting freedom of the foot during walking, that could be involved in maintaining balance. An 1stMTPJ angle of 20º, where distinct limitations were observed, might serve as a criterion of HV pathology.

Decreased Bone Mineral Density in Forearm vs Loaded Skeletal Sites in Professional Ballet Dancers.

AIMS: To compare the differences in bone mineral density (BMD) at loaded and non-loaded skeletal sites in professional ballet dancers. We hypothesized that in both male and female elite ballet dancers, a significant difference in BMD will be observed between impact and non-impact sites. METHODS: 44 elite ballet dancers, 22 men (age 26.4±5.9 yrs) and 22 women (age 24.9±5.3 yrs), were examined. BMD measurements were performed using dual-energy x-ray absorptiometry at three skeletal sites-forearm (FA), lumbar spine (LS), and femoral neck (FN)-and analyzed using t-tests, ANOVA, and linear regression models. Information about career duration, training volume, health habits, and menstrual disorders (women) was collected. RESULTS: Z-scores for LS and FN were significantly higher in men than in women. However, Z-scores for FA were similar in men and women and fell below the expected range for age (<-2.0), and they were significantly lower than those for LS and FN. With longer career duration, a trend was observed towards lower Z-scores for FN in men and towards higher Z-scores for FA in women. CONCLUSION: In ballet dancers, FA mineralization is extremely low compared to loaded skeletal sites. Male dancers may have lowered forearm BMD despite the absence of risk factors present in female dancers (menstrual disorders). Professional ballet dancers may be at risk of local osteopenia due to the "local non-impact" characteristics of ballet dance, and use of the 33% distal radius region for the accurate assessment of bone mineral status should be investigated further in this population.

Reference values of spatiotemporal parameters, joint angles, ground reaction forces, and plantar pressure distribution during normal gait in young women.

PURPOSE: The aim of this study was to establish the reference values of spatiotemporal parameters, joint angles, ground reaction forces and plantar pressure distribution collected simultaneously on the same measurement path during normal gait in a homogenous group of young, healthy women. METHODS: The studied group consisted of 28 healthy women aged 21 years on average. The motion capture system BTS Smart-D, 2 AMTI force platforms and Footscan pedobarographic platform were used in this research. The 14-metre measurement path and the 6-metre distance that examined women had to walk through before entering the measurement area ensured that a natural gait pattern was recorded. Statistical analysis was performed to evaluate differences between right and left lower extremities. RESULTS: The applied method enabled collecting several parameters regarding normal female gait biomechanics such as: spatiotemporal parameters, angle-time characteristics as well as range of motion of pelvis, hip, knee and ankle joints in gait cycle, force-time characteristics and peaks of ground reaction force components in stance phase, peak pressure and time of loading of defined foot regions in stance phase. CONCLUSIONS: The results may be used by clinicians, physiotherapists or researchers as a reference in diagnosing gait disorders or evaluating patient's walking pattern. In recent literature there are some disparities in gait parameters reference values even regarding similar research groups. These differences may arise from distinct method, slower or faster gait, other laboratory environment etc. This should be considered and more than one source of normative values should be checked when searching for reference data.

Prophylaxis of medial compartment gonarthrosis in varus knee - current state of knowledge.

The progression of gonarthrosis results in reduction of physical activity. One of the factors that increase the risk of osteoarthrosis may be joint overload related to the malalignment of the mechanical axis of the lower extremity. The medial compartment (MC) of the knee is particularly susceptible to overload due to the external knee adduction moment (EKAM). Varus knee malalignment contributes to increased EKAM and thus results in increased MC loading. The purpose of this study is to present methods described in current literature aimed at reducing the disproportion in the distribution of loads on articular surfaces of medial and lateral knee compartments in people with varus knee malalignment. Methods have been divided into non-surgical (gait training, physiotherapy, and orthopedic supplies such as valgus braces, lateral wedge insoles, walking poles) and surgical ones (corrective osteotomy).

Dynamic parameters of three-point crutch gait in female patients after total hip arthroplasty.

PURPOSE: Patient recovery after a surgical procedure depends, among other factors, on the amount of the body weight with which patient loads lower limb. Research studies report different results of the degree of body weight with which lower limb is loaded during three-point crutch gait. The aim of this study was to evaluate the level of the ground reaction forces (GRF) during crutch gait used by patients after total hip arthroplasty (THA) in the first week after discharge from the orthopaedic units. METHODS: Ten female patients diagnosed with primary unilateral coxarthrosis participated in a single measurement session. In order to record kinematic and dynamic variables of this gait pattern motion analysis system was used together with two force plates. The static test of body weight distribution between lower limbs was performed on a dual-top stabilometric plate. RESULTS: The average peak values of loading on the operated (O) limb during mid stance and terminal stance of three-point crutch gait were 64.6% and 64.3% of body weight (BW), respectively, whereas in the case of the nonoperated (NO) limb 103.5%BW and 108.8%BW, respectively. The maximum loads on the crutches were significantly higher (by 9%BW) on the NO side as compared to the O side ( p < 0.05). During the static test, average values of body weight distribution on the O and NO limb were 36%BW and 64%BW, respectively. CONCLUSIONS: The patients showed surprisingly similar level of loading on the O limb. The weight bearing on the O limb was lower during static trial than during three-point crutch gait.

The significance of body mass index in calculating the cut-off points for low muscle mass in the elderly: methodological issues.

OBJECTIVES: Cut-off points (COPs) for appendicular lean mass (ALM) index, essential to define low muscle mass (LMM) in the elderly, have never been officially defined for Poland. The aim of the study was to establish them. Additionally, the significance of body mass index (BMI) for correctly defining the COPs in a young, healthy reference group was assessed. METHODS: The study was composed of reference group (n = 1113) and the elderly group (n = 200). In all subjects, body composition was assessed by bioimpedance analysis, and ALM index was calculated. Next, COPs (kg/m(2)) were set up for the whole reference group and for particular subgroups with different BMIs separately. They were used to diagnose sarcopenia in the elderly. RESULTS: COP for all young females was 5.37 (COP-F), while it was equal to 5.52 (COP-F2) when only those with a recommended BMI (18.50-24.99 kg/m(2)) were taken into consideration. For males, it was 7.32 and 7.29, respectively. Only 7% of elderly females had LMM based on COP-F and 15% had LMM based on COP-F2 (P < 0.05); for males, the percentages were 18% and 16%, respectively. CONCLUSIONS: COPs for LMM for Poland are 5.52 kg/m(2) (females) and 7.29 kg/m(2) (males). The reference group BMI is an important factor in establishing COPs for low muscle mass.

Kinematic analysis of modern dance movement "stag jump" within the context of impact loads, injury to the locomotor system and its prevention.

BACKGROUND: This paper presents a case study of kinematic analysis of the modern dance movement known as the "stag jump". Detailed analysis of the kinematic structure of this movement as performed by the dancers, accompanied by measurements of impact forces during landing, will allow the authors to determine, in subsequent model-based research phases, the forces acting in knee joints of the lower landing limb. MATERIAL AND METHODS: Two professional modern dancers participated in the study: a male and a female. The study consisted in recording the values of ground reaction and body motion, and then determining and analyzing kinematic parameters of performed movements. RESULTS: The results of measurement of joint angles in the landing lower limb, pelvis, and foot position in relation to the ground, as well as the level of vertical components of ground reaction, provided insight into the loading response phase of the "stag jump". The measurements and obtained results show differences between the man and woman in ground reactions and kinematic quantities. CONCLUSIONS: The results obtained during the research may be used in the development and teaching of dancing movements. Training sessions, carried out in the biomechanical laboratory, with active participation of dancing teachers, could form a basis for a prevention model of injuries and physical overloads occurring within this occupational group. Primary differences in the "stag jump" performance technique probably result from the different educational path the man and the woman went through.

Spinal alignment in surgical, multisegmental, transpedicular correction of adolescent idiopathic scoliosis.

The objective of this study was to discuss the variables influencing alignment mechanisms of the spine, with particular consideration of post-surgical alignment in adolescent idiopathic scoliosis. The analysis is based on information currently available in the literature, and on the authors' own experience, which includes surgical material from over 2200 cases of idiopathic scoliosis. Over 50% of cases of adolescent idiopathic scoliosis are decompensated before surgical treatment. Spinal alignment is most significantly influenced by the position of the pelvis. Surgical restoration of lumbar lordosis is more important than attempting to restore thoracic kyphosis in the sagittal plane. The sagittal profile has an essential impact on spinal alignment. The same curves in the coronal plane can have various 3-dimensional configurations. Clinical difficulties in the assessment of thoracic kyphosis and lumbar lordosis result from the fact that they undergo constant change with age. Thoracic hypokyphosis diagnosed before surgery is a very frequent symptom of curve progression. The presence of proximal (thoraco-thoracic) and distal (thoraco-lumbar) junctional kyphosis is very important for planning the scope of spondylodesis. The natural tendency of the spine for alignment (compensation) after surgery nowadays occurs more naturally by applying derotational forces through pedicle screws, compared to the distraction devices (eg, Harrington rod) used in the past.

Three point crutch gait from the perspective of biomechanics and kinesiology. State of knowledge and idea behind the research.

The study characterizes the idea behind the research project which consists in biomechanical and kinesiological analysis of three point crutch gait. The structure of the study is in part similar to an earlier publication of the authors [1], which discussed swing through gait. By defining the three point crutch gait and describing its general kinematic structure as well as synthetically analyzing the state of knowledge, the authors formulated the purpose of the study, the adopted research model - including the description of the modern and integrated measurement systems that were used and which consisted of: 2 AMTI force plates integrated into a measurement walkway, a set of 6 optoelectronic cameras of the BTS System as well as a multichannel kinesiological electromyography performed with the use of the NORAXON System. All phases of the research were characterized, presenting the adopted research protocol in its entirety.

Sports biomechanics in the research of the Department of Biomechanics of University School of Physical Education in Poznan. Part 1. Biomechanics of rowing: tests on rowing ergometers, reconstruction and synthesis.

The purpose of this study is to reconstruct the early phase of scientific research conducted at the Department of Biomechanics of the University School of Physical Education in Poznan, particularly the work on biomechanics of rowing, conducted as part of the Ministerial Project PR 105, entitled "The effectiveness of training and competition as well as regeneration in sports". Three kinds of research have been described, carried out with the use of the rowing ergometers. The first was the research on neuromuscular coordination in the rowing cycle, the second was the research on kinematic and dynamic characteristics of rowing on the Universal Rowing Ergometer UEW - 1, while the last one concerned determination of maximum forces generated by functional muscle groups in two characteristic rowing positions within the closed biochain of the torso and the limbs.

[Analysis of knee joint injuries of competitive volleyball players in selected sports clubs of Poznan city--biomechanical context. Synthesis--proposal for the usage of physiotherapy methods in the prevention of the discussed injuries]. / Analiza urazów stawu kolanowego u trenujacych wyczynowo pilke siatkowa w wybranych klubach poznanskich--kontekst biomechaniczny. Synteza problemu--propozycja wykorzystania metod fizjoterapeutycznych w profilaktyce omawianych urazów.

INTRODUCTION: Volleyball is a source of direct injuries and chronic overloads of the joints, which indirectly results in traumas and permanent dysfunctions. This applies particularly to: knee joints, ankle joints, shoulder joints and small joints of the hand, as well as the joints of the lower spine regions. Each league team should employ a physiotherapist who would be responsible for the implementation of an injury prevention program as well as for choosing the right training loads. PURPOSE: The purpose of this study is to analyze the frequency and the type of knee joint injuries occurring in people practicing Volleyball at competitive level as well as to propose the usage of elements of modern physiotherapy in order to prevent these injuries. MATERIAL AND METHODS: The tests were performed over a group of 19 volleyball players from Poznan. In order to propose measures that would prevent injuries, the authors carried out a review of modern physiotherapy methods and suggested the implementation of certain therapeutic techniques for the region of the knee joint. RESULT ANALYSIS AND DISCUSSION: As much as 79% of the subjects reported having chronic pain and knee joint injuries in the past. All of them, due to their conditions, declared having used various forms of physiotherapy treatment. It seems that in a professional sports club not only the presence of a massage therapist but first of all a qualified physiotherapist is indispensable.

Sports biomechanics in the research of the Department of Biomechanics of University School of Physical Education in Poznan. Part 2. Biomechanics of rowing: research conducted in the rowing pool and under real conditions. Reconstruction and synthesis.

The purpose of this study was to reconstruct the early phase of scientific research conducted at the Department of Biomechanics of the College of Physical Education and since 1972 at the University School of Physical Education in Poznan, with special attention paid to the works on biomechanics of rowing, carried out as part of the Ministerial Project PR 105 entitled The effectiveness of training, sports competition as well as regeneration in sports. Two kinds of biomechanical research are described: the several years' expert research conducted on the Rowing National Team in an original two-module Rowing Pool Testing Station BTW-1, as well as research on geometric optimization of the rowing station, conducted under real conditions, in reservoirs, with the use of a prototypical, unique at that time, computer measurement system BIOMIK, installed in the rower's own boat. The projects were carried out by doctoral students from the Department of Biomechanics and the Department of Clinical Biomechanics, Andrzej Lisiecki and Wojciech Mikolajczyk, respectively.

[Swing-through gait from the perspective of biomechanics and kinesiology. Critical analysis of the current state of knowledge and the idea behind the research]. / Chód kangurowy z perspektywy biomechaniki i kinezjologii. Krytyczna analiza stanu wiedzy i koncepcja badan.

The study defines the idea behind the research project which analyzes the swing-through gait from the biomechanical and kinesiological perspective. In the preliminary phase, the authors performed a synthetic analysis of the state of knowledge, created a description of the general kinematic structure of the swing-through gait as a form of locomotion with the use of crutches, proposed definitions. The problem was described with the use of time characteristics of vertical and horizontal anterior-posterior as well as lateral components of ground reaction forces, measured from under the supporting limb and the crutches. Presenting the idea behind the research project, the authors defined in detail the purpose of the study, the assumptions, research methodology--including a description of methods used and the measurement channels which consisted of: 2 AMTI force platforms integrated into a measurement walkway, a set of 6 optoelectronic cameras of the BTS System as well as a multichannel kinesiologic electromyography performed with the use of the NORAXON System. All phases of the research were characterized, presenting the research protocol in its entirety. The research will be conducted in the Laboratory of the Department of Biomechanics of USPS in Poznan, which possesses the ISO 9001:2008 quality management system certificate.

[Assessment of stretching techniques for neck and arms muscles in physiotherapy following total laryngectomy]. / Ocena techniki rozciagajacej miesnie okolicy szyi i barków w rehabilitacji chorych po calkowitym usunieciu krtani.

After total laryngectomy and after complete treatment (radiotherapy) there are many functional disorders in the range of head and neck. These decrease muscle strength and flexibility of muscles of cervical spine. This causes disorders of physiological range of motions of this area. The introduction of the stretching techniques (postisometric relaxation) to the physiotherapy program allows to decrease negative effects of treatment, mentioned above. The therapy of main cervical muscles was carried out during a two week rehabilitation camp. Biomechanical-kinesiological tests were used to assess the effect of the physiotherapy program. The application of postisometrical relaxation and the massage of the cervical and arm muscles increased the average motor ranges and muscle strength. Cervical muscles disbalance was decreased at the same time.