Kinetics, kinematics, and knee muscle activation during sit to stand transition in unilateral and bilateral knee osteoarthritis.

BACKGROUND: The sit to stand transition (STS) is a task performed by those with knee osteoarthritis (KOA) with biomechanical modifications that may influence the lower limb load distribution. As a weight bearing task mainly performed in the sagittal plane, the presence of unilateral or bilateral KOA may lead to asymmetry during its performance. RESEARCH QUESTION: Are the biomechanical and neuromuscular aspects of the sit to stand transition (STS) different between participants with unilateral and bilateral KOA? METHODS: Twenty-eight participants were allocated as follows: unilateral KOA (OAUNI; n = 12) and bilateral KOA (OABI; n = 16). All participants were evaluated by means of kinematics (Qualisys Motion Capture System, Qualisys Medical AB, SUE), kinetics (Bertec Corporation's model 4060-08 Mod., USA), and electromyography (TrignoTM Wireless System, DelSys Inc., USA) during the STS. The variables calculated were the symmetry indices of the total support moment (TSM) and ground reaction force (ISGRF and ISTSM, respectively), magnitude of the TSM, individual joint contribution to the TSM, peak trunk flexion, hip, knee, and ankle range of motion, duration in seconds, the magnitudes of activation of the extensor and flexor muscles, knee extensors: flexor co-contraction indices and isometric knee extensor peak torques. Participants also answered the WOMAC questionnaire and performed the 30-second STS test (STS30). RESULTS: The OABI got up from a chair with a lower TSM magnitude in the most affected limb (p = 0.040), used greater trunk flexion amplitude (p ≤ 0.034), and presented lower isometric KET (p = 0.039) and worse self-reported pain (p = 0.011) and physical function (p = 0.015). SIGNIFICANCE: Participants with unilateral and bilateral KOA differ regarding lower limb kinetics and trunk kinematics while getting up from a chair, without modification in the lower limb intersegmental coordination or symmetry regarding ground reaction force or TSM distribution.

Y-Balance Test Asymmetry and Frontal Plane Knee Projection Angle During Single-leg squat as Predictors of Patellofemoral Pain in Male Military Recruits.

OBJECTIVES: Investigate prospectively whether dynamic balance and frontal plane knee projection angle (FPKPA) are risk factors for the development of patellofemoral pain (PFP) in male military recruits. STUDY DESIGN: Prospective cohort. SETTING: Military training center. PARTICIPANTS: 135 male military recruits were followed prospectively for six weeks and the incidence of PFP was documented. MAIN OUTCOMES: Baseline measures of the Y-Balance test (YBT) and two-dimensional FPKPA during single-leg squatting were recorded. Mann-Whitney U tests and logistic regression analysis were utilized to identify possible variables associated with the development of PFP. RESULTS: A total of 14 male recruits developed PFP during the follow up period. The PFP group had significantly greater asymmetry on the YBT posterolateral direction (mean difference = 3.44 ± 0.57 cm; 95% Confidence Interval [CI] = 2.38-4.51 cm) and greater FPKPA during single-leg squat (mean difference = 5.55°±1.78°; [CI] = 1.81-9.28°) at baseline when compared to controls. Binary logistic regression models revealed that YBT posterolateral asymmetry ≥4.08 cm (Nagelkerke R2 = 0.304; X2 = 21.63; p < 0.001; OR = 5.46; [CI] = 4.47-8.06) and FPKPA ≥ 4.81° (Nagelkerke R2 = 0.249; X2 = 17.46; p < 0.001; OR = 4.65; [CI] = 3.32-9.06) were significantly associated with PFP. CONCLUSIONS: Male military recruits with greater asymmetry on the YBT posterolateral direction and FPKPA were at a greater risk of developing PFP.

Effects of three gait retraining techniques in runners with patellofemoral pain.

OBJECTIVES: Analyze the effects of 3 gait retraining: forefoot landing (FFOOT), 10% step rate increase (SR10%) and forward trunk lean (FTL) on lower limb biomechanics and clinical measurements in patellofemoral pain (PFP) runners. DESIGN: Case series report. SETTINGS: Biomechanical laboratory and treadmill running. PARTICIPANTS: Eighteen recreational PFP runners randomized in 3 groups. MAIN OUTCOME MEASURES: Lower limb kinematics and muscle activation were assessed at baseline and 2-week post-training. Pain intensity and function limitation, measured by AKPS (Anterior Knee Pain Scale) and LEFS (Lower Extremity Functional Scale) assessed at baseline, post-training and 6-month follow-up. Repeated measures analysis of variance was used to compare the effects of gait retraining. RESULTS: FFOOT and FTL increased the AKPS score at post-training(P = .001; P = .008) and 6-month follow-up(P < .001; P < .001). SR10% increased the AKPS score from baseline to 6-month follow-up(P = .006). Pain and LEFS score were improved after gait retraining regardless group. FFOOT presented greater gastrocnemius(P = .037) and rectus femoris pre-activation(P = .006) at post-retraining session. Gait retraining reduced the muscle activity during stance phase and increased during the late-swing regardless group. CONCLUSION: The three techniques presented clinical benefits, improvement of pain symptoms and functional scores, was not accompanied with significant biomechanics differences that could entirely explain this clinical improvement after the intervention.

Association of Hip and Trunk Strength With Three-Dimensional Trunk, Hip, and Knee Kinematics During a Single-Leg Drop Vertical Jump.

Martinez, AF, Lessi, GC, Carvalho, C, and Serrao, FV. Association of hip and trunk strength with three-dimensional trunk, hip, and knee kinematics during a single-leg drop vertical jump. J Strength Cond Res 32(7): 1902-1908, 2018-Kinematic changes have been correlated with different lower-limb injuries. Movement is influenced by multiple factors and strength is one of the contributors that can influence it. Thus, the aim of this study was to evaluate the correlation among trunk and hip isometric strength with trunk and lower-limb kinematics during a single-leg drop vertical jump. Twenty-three healthy recreational female athletes aged between 18 and 35 years underwent isometric evaluation of hip abductor, hip extensor, and lateral trunk muscle strength and 3-dimensional trunk and lower-limb kinematics during a single-leg drop vertical jump. Pearson's correlation coefficients (r) were calculated to establish the association among hip and trunk strength and trunk, hip, and knee kinematics. As result, no significant correlations were found between the peak and movement excursion values of kinematic and hip and trunk isometric strength data. The lack of correlation between isometric strength and kinematics in healthy female athletes indicates that intervention programs should not be focused solely on strength exercises to influence the movement pattern during single-landing activities.

Men with early degrees of knee osteoarthritis present functional and morphological impairments of the quadriceps femoris muscle.

OBJECTIVE: Quadriceps muscle weakness is common in knee osteoarthritis (OA). Reasons for weakness may include atrophy, reduction in the muscle fibers number, and changes in the muscle activation. It is uncertain when these muscular changes begin to appear. Therefore, the purpose of this study was to determine whether men with early stages of knee OA already had functional and quadriceps muscle morphologic alterations. DESIGN: Forty men were divided into two groups: control group (healthy subjects) and OA group (subjects with knee OA). A biopsy of the vastus lateralis muscle was performed for morphometric analysis. Isokinetic evaluation of knee extensor torque, concentric and eccentric (90 and 180 degrees/sec), was performed simultaneously with vastus lateralis electromyographic activity evaluation. RESULTS: Significant differences were found in knee extensor torque (P < 0.05) and in normalized root mean square (P < 0.01) during the eccentric contractions (both velocities), with higher values for the control group. No differences were found during concentric contractions. The OA group presented greater values of the minimum diameter of type 1 fibers and greater proportion and relative cross-sectional area of type 2b fibers (P < 0.05). CONCLUSIONS: Men with early stages of knee OA do not present alterations of concentric strength but had decreased eccentric strength and morphologic quadriceps muscle changes, indicating neuromuscular adaptations.

Expression of receptors of advanced glycation end product (RAGE) and types I, III and IV collagen in the vastus lateralis muscle of men in early stages of knee osteoarthritis.

Alterations in the contractile and non-contractile proteins of the skeletal muscle may reduce muscle function in knee osteoarthritis (OA), and the formation and accumulation of advanced glycation end products, particularly in collagen, can influence the quality of these muscle proteins. The objective of this study was to evaluate the reactivity of types I, III and IV collagen and the expression and localization of receptor for advanced glycation end products (RAGE) in the vastus lateralis (VL) muscle in early stages of knee OA. The hypothesis was that these patients present a higher expression of RAGE and increased immunoreactivity in the collagen. Thirty-five men were divided into two groups: the control group (CG; n = 17) and the osteoarthritis group (OAG; n = 18). All participants were submitted to a biopsy of the VL. The muscle samples were analyzed by immunohistochemistry for collagen and for RAGE and laminin. The expression of RAGE was counted (intracellular, extracellular and total). Student's t-test for independent samples and Mann-Whitney U test were used for the RAGE's intergroup analysis (α ≤ 0.05). A semiquantitative analysis was performed to assess the collagen reactivity. No significant differences were observed in the intracellular, extracellular or total localization of RAGE (p > 0.05). Higher immunoreactivity was observed in the OAG for all types of collagen, with more reactivity for collagen III and IV. We concluded that in the initial stages of knee OA, no differences were observed for RAGE levels between the groups. However, the OAG's higher collagen expression may represent adaptations for reducing muscle stiffness and avoiding injury.

Knee extensor torque of men with early degrees of osteoarthritis is associated with pain, stiffness and function / Homens com graus iniciais de osteoartrite apresentam correlação entre torque extensor do joelho e dor, rigidez e função

BACKGROUND: Osteoarthritis (OA) is a chronic-degenerative disease. The knee is the most commonly affected joint and the symptoms are generally attributed to quadriceps muscle weakness. However, few studies have evaluated this relationship in a population with early stages of knee OA. OBJECTIVE: To investigate whether a correlation among the knee extensor torque and the three subscales of the WOMAC questionnaire in men with early stages of knee OA exists. METHOD: Twenty-one men with knee OA grades I or II (according to Kellgren and Lawrence criteria) participated in this study. The concentric and eccentric knee extensor torque were assessed using a Biodex System 3 Pro® isokinetic dynamometer, at a speed of 90º/s. Self-reported symptoms and disability were assessed using the WOMAC questionnaire. Spearman's correlation coefficient was used to test the relationship between the dependent variables (three subscales of WOMAC questionnaire) and the independent variables (average knee extensor peak torque). RESULTS: We found a strong negative correlation between the concentric extensor torque and pain (r=-0.7, p<0.001) and a moderate and negative correlation among the concentric extensor torque and stiffness (r=-0.62, p=0.002) and physical function (r=-0.54, p=0.011). Eccentric extensor torque presented a moderate and negative correlation with the three subscales of the WOMAC (r=-0.40 to 0.69, p<0.05). CONCLUSIONS: The concentric and eccentric knee extensor torque is significantly correlated with self-report symptoms of patients in initial stages of knee OA. Therefore, the strengthening of the quadriceps muscles, through concentric and eccentric exercise is indicated for these patients in order to minimize these symptoms.

CONTEXTUALIZAÇÃO: A osteoartrite (OA) é uma doença crônico-degenerativa. O joelho é a articulação mais afetada, e os sintomas geralmente são atribuídos à fraqueza do músculo quadríceps. Entretanto, poucos estudos têm avaliado essa relação em indivíduos com graus iniciais de OA. OBJETIVO: Verificar se existe correlação entre o torque extensor do joelho e as seções dor, rigidez e função física do questionário WOMAC de homens com OA de joelho nos graus iniciais. MÉTODO: Participaram deste estudo 21 homens com OA de joelho graus I ou II (segundo critérios de Kelgren e Lawrence). Foi avaliado o torque extensor concêntrico e o excêntrico do joelho por meio do dinamômetro isocinético (Biodex System 3 Pro®), na velocidade de 90º/s. O autorrelato de sintomas e incapacidades foi avaliado por meio do questionário WOMAC. O Coeficiente de Correlação de Spearman foi utilizado para detectar a relação entre as variáveis dependentes (três seções do questionário WOMAC) e as variáveis independentes (média dos picos de torque). RESULTADOS: Encontrou-se correlação forte e negativa do torque extensor concêntrico com a seção dor (r=-0,7, p<0,001) e moderada e negativa com as seções rigidez (r=-0,62, p=0,002) e função física (r=-0,54, p=0,011). O torque extensor excêntrico correlacionou-se moderada e negativamente com as três seções do questionário (r=-0,40 a -0,69, p<0,05). CONCLUSÕES: Os torques extensores concêntrico e excêntrico correlacionaram-se com os sintomas autorrelatados pelos indivíduos com graus iniciais de OA de joelho. Assim, o fortalecimento do músculo quadríceps, por meio de exercícios concêntricos e excêntricos, é indicado para esses pacientes para minimizar tais sintomas.

Knee extensor torque of men with early degrees of osteoarthritis is associated with pain, stiffness and function.

BACKGROUND: Osteoarthritis (OA) is a chronic-degenerative disease. The knee is the most commonly affected joint and the symptoms are generally attributed to quadriceps muscle weakness. However, few studies have evaluated this relationship in a population with early stages of knee OA. OBJECTIVE: To investigate whether a correlation among the knee extensor torque and the three subscales of the WOMAC questionnaire in men with early stages of knee OA exists. METHOD: Twenty-one men with knee OA grades I or II (according to Kellgren and Lawrence criteria) participated in this study. The concentric and eccentric knee extensor torque were assessed using a Biodex System 3 Pro® isokinetic dynamometer, at a speed of 90º/s. Self-reported symptoms and disability were assessed using the WOMAC questionnaire. Spearman's correlation coefficient was used to test the relationship between the dependent variables (three subscales of WOMAC questionnaire) and the independent variables (average knee extensor peak torque). RESULTS: We found a strong negative correlation between the concentric extensor torque and pain (r=-0.7, p<0.001) and a moderate and negative correlation among the concentric extensor torque and stiffness (r=-0.62, p=0.002) and physical function (r=-0.54, p=0.011). Eccentric extensor torque presented a moderate and negative correlation with the three subscales of the WOMAC (r=-0.40 to 0.69, p<0.05). CONCLUSIONS: The concentric and eccentric knee extensor torque is significantly correlated with self-report symptoms of patients in initial stages of knee OA. Therefore, the strengthening of the quadriceps muscles, through concentric and eccentric exercise is indicated for these patients in order to minimize these symptoms.

Muscle atrophy and functional deficits of knee extensors and flexors in people with chronic stroke.

BACKGROUND: Further clarification is needed with regard to the degree of atrophy in individual muscle groups and its possible relationship to joint torque deficit poststroke. OBJECTIVE: The purpose of this study was to investigate quadriceps and hamstring muscle volume and strength deficits of the knee extensors and flexors in people with chronic hemiparesis compared with a control group. DESIGN: This was a cross-sectional study. METHODS: Thirteen individuals with hemiparesis due to chronic stroke (hemiparetic group) and 13 individuals who were healthy (control group) participated in this study. Motor function, quadriceps and hamstring muscle volume, and maximal concentric and eccentric contractions of the knee extensors and flexors were assessed. RESULTS: Only the quadriceps muscle of the paretic limb showed reduced muscle volume (24%) compared with the contralateral (nonparetic) limb. There were no differences in muscle volume between the hemiparetic and control groups. The peak torque of the paretic-limb knee extensors and flexors was reduced in both contraction modes and velocities compared with the nonparetic limb (36%-67%) and with the control group (49%-75%). The nonparetic limb also showed decreased extensor and flexor peak torque compared with the control group (17%-23%). Power showed similar deficits in strength (12%-78%). There were significant correlations between motor function and strength deficits (.54-.67). LIMITATIONS: Magnetic resonance imaging coil length did not allow measurement of the proximal region of the thigh. CONCLUSIONS: There were different responses between quadriceps and hamstring muscle volumes in the paretic limb that had quadriceps muscle atrophy only. However, both paretic and nonparetic limbs showed knee extensor and flexor torque and power reduction.