Effect of Force Sense to Active Joint Position Sense and Relationships between Active Joint Position Sense,Force Sense,Jumping and Muscle Strength

Abstract

We aimed to investigate the effect of external load on the joint position sense (JPS) accuracy and its relation to the target jump height. The present study also aimed to explore the relationship between force sense (FS) and maximum voluntary isometric contraction (MVIC). Participants’ MVIC levels were determined during the 45-degree knee extension task. Then, participants were asked to execute a knee JPS task with external load (EL-JPS) and with no-load (EL-JPS). To assess jumping accuracy participants were instructed to jump with their 50% of maximum jump height. Results indicated that EL-JPS error values were lower than NL-JPS. EL-JPS was correlated to jumping errors. However, the relationship between NL-JPS and jumping errors was not significant. A significant correlation was found between MVIC and FS errors.     

Effects of electromyostimulation on knee extensors and flexors strength and steadiness in older adults

It is known that electromyostimulation (EMS) alone or superimposed over voluntary contraction (EV) can effectively improve muscle strength. However, the effect of this type of training on the ability to control force production at submaximal levels is unknown. The authors examined the effects of EV training on steadiness in force production of knee extensors and flexors in older adults. Forty participants, including 20 men and 20 women, 60-77 years of age, were randomly allocated into a control group (CG) and an electromyostimulation superimposed over voluntary contraction (EVG) group. The EVG performed 30 bilateral isometric knee extension and flexion contractions per session, 3 training sessions per week, for 6 weeks. The variations in force production, expressed in absolute (standard deviation [SD]) and relative (coefficient of variation [CV]) terms, were assessed in isometric contractions at 5%, 15% and 25% maximal voluntary contraction (MVC) levels. Results indicated that MVC increased in knee extension and flexion in EVG (p < .05) after the training; steadiness CV also improved at 15% MVC in knee flexion (p < .05) but no significant changes were found in knee extension and steadiness SD. The training-induced changes in MVC were not correlated to steadiness CV that might indicate different mechanisms underlying these adaptations.     

Magnitude of force perception errors during static contractions of the knee extensors in healthy young and elderly individuals

The accuracy of force perception during muscular contraction has not been studied extensively, despite its importance in rehabilitation and training. The purpose of this study was to quantify the errors made by healthy young and elderly individuals in their perceptions of force produced at the knee. Four different tasks were used to evaluate the perception of force and the effect of a sensory-motor reference and simultaneous contraction on the accuracy of perception. The absolute errors were similar between groups, with values of 11.9% to 16.3%, depending on the task. The raw perception errors were greater for high levels of force (>50% of the maximal voluntary contraction, or MVC), indicating an overestimation of the forces produced for both groups. At 70% MVC, the sensory-motor reference reduced raw perception errors, and the simultaneous contraction improved the accuracy of force production. Healthy young and elderly individuals had about the same capacity to judge the muscular force of their knee extensors. Therapists involved in the training of active?elderly?individuals should be aware that the accuracy of force perception is not perfect and that these clients have the same ability as young individuals to perceive their knee extension strength.     

Effects of Electromyostimulation on Knee Extensors and Flexors Strength and Steadiness in Older Adults

It is known that electromyostimulation (EMS) alone or superimposed over voluntary contraction (EV) can effectively improve muscle strength. However, the effect of this type of training on the ability to control force production at submaximal levels is unknown. The authors examined the effects of EV training on steadiness in force production of knee extensors and flexors in older adults. Forty participants, including 20 men and 20 women, 60–77 years of age, were randomly allocated into a control group (CG) and an electromyostimulation superimposed over voluntary contraction (EVG) group. The EVG performed 30 bilateral isometric knee extension and flexion contractions per session, 3 training sessions per week, for 6 weeks. The variations in force production, expressed in absolute (standard deviation [SD]) and relative (coefficient of variation [CV]) terms, were assessed in isometric contractions at 5%, 15% and 25% maximal voluntary contraction (MVC) levels. Results indicated that MVC increased in knee extension and flexion in EVG (p < .05) after the training; steadiness CV also improved at 15% MVC in knee flexion (p < .05) but no significant changes were found in knee extension and steadiness SD. The training-induced changes in MVC were not correlated to steadiness CV that might indicate different mechanisms underlying these adaptations.     

Age-related changes in multi-finger interactions in adults during maximum voluntary finger force production tasks

This study aimed to continue our characterization of finger strength and multi-finger interactions across the lifespan to include those in their 60s and older. Building on our previous study of children, we examined young and elderly adults during isometric finger flexion and extension tasks. Sixteen young and 16 elderly, gender-matched participants produced maximum force using either a single finger or all four fingers in flexion and extension. The maximum voluntary finger force (MVF), the percentage contributions of individual finger forces to the sum of individual finger forces during four-finger MVF task (force sharing), and the non-task finger forces during a task finger MVF task (force enslaving), were computed as dependent variables. Force enslaving during finger extension was greater than during flexion in both young and elderly groups. The flexion-extension difference was greater in the elderly than the young adult group. The greater independency in flexion may result from more frequent use of finger flexion in everyday manipulation tasks. The non-task fingers closer to a task finger produced greater enslaving force than non-task fingers farther from the task finger. The force sharing pattern was not different between age groups. Our findings suggest that finger strength decreases over the aging process, finger independency for flexion increases throughout development, and force sharing pattern remains constant across the lifespan.     

The development of hand preference in children: The effect of task demands and links with manual dexterity

Lateralisation of hand preference and manual dexterity are known to develop over childhood, while in adulthood strength of hand preference has been shown to interact with extrinsic task demands. Some evidence exists to suggest that strength of hand preference and motor skill may be related. In the current study a handedness inventory, midline crossing (QHP) and peg-moving tasks were used to investigate: (1) the development of hand preference between 4 and 11 years; (2) whether extrinsic task demands affect strength of hand preference, and (3) whether strength of hand preference was associated with manual dexterity. Younger children (4–5 years) showed weak hand preference in comparison to older children (8–11 years), and extrinsic task demands influenced willingness to cross the body’s midline with the preferred hand. Age and peg-moving speed were associated with midline crossing in certain task conditions. Overall, results suggest a coupling between manual dexterity and brain maturation in typical development.     

Height of chair seat and movement characteristics in sit-to-stand by young and elderly adults

The height of a chair seat affects the burden on the lower limbs during the sit-to-stand (STS). To develop an objective test to evaluate muscle function of the lower limbs using floor reaction force during a STS, the relationship between chair-seat height and the burden on the lower legs must be assessed. To examine the influence of the chair-seat height, floor reaction forces during a STS performed with 5 chair heights adjusted to each subject's lower leg length were compared. The force production and quickness of movement tended to decrease in the phases of trunk flexion and knee and hip joint extension when performing a STS from a lower chair, when the chair height differed by 20% (6.2 cm) from the lower leg length, and was marked when the difference between chair height and lower leg length became larger. In 52 elderly and 50 young adults, floor reaction forces during a STS performed from a chair of the same height as subjects' lower leg lengths were compared. Elderly persons were inferior in force production (strength) and quickness of movement, which decreased as elderly stood up from a chair of a lower height.     

Do knee concentric and eccentric strength and sagittal-plane knee joint biomechanics differ between jumpers and non-jumpers in landing?

The purpose of this study was to investigate the differences of knee concentric and eccentric strength and impact related knee biomechanics between jumpers and non-jumpers during step-off landing tasks. Ten male college swimming athletes (non-jumpers) and 10 track and volleyball athletes (jumpers) were recruited to participate in two test sessions: a muscle strength testing session of concentric and eccentric extension for dominant knee joint at 60 °/s and 180 °/s and a landing testing session. The participants performed five trials of step-off landing in each of four conditions: soft and stiff landing from 0.4 m and 0.6 m landing heights. The three-dimensional kinematics and ground reaction force were recorded simultaneously during step-off landing conditions. The results showed that the jumpers had significantly greater peak knee eccentric extension and concentric flexion torques compared to the non-jumpers. No significant group effects were found for peak vertical ground reaction force and knee range of motion during landing. The jumpers had significantly greater knee contact flexion angle, maximum knee flexion angle and initial knee extension moment compared to the non-jumpers. These results suggest that these athletes adopted a favorable impact attenuation strategy that is related to the greater knee eccentric muscle strength and training.     

Effect of added mass on human unipedal hopping at three frequencies

Although more commonly done by children, hopping appears to be a rich source of neuromuscular and biomechanical information on adults. Given prior research on the independent effects of hopping frequency and added mass, this study assessed whether these would interact to affect vertical stiffness, contact duration, and lower extremity kinematics during unipedal hopping. Vertical force and two-dimensional kinematics were measured in 10 healthy males hopping at three frequencies: their preferred hopping frequency and frequencies 20% higher and 20% lower, in two conditions with added mass (body mass+10% and body mass+20%). Vertical stiffness was directly related to hopping frequency, while hip flexion, knee flexion, and ankle dorsiflexion were inversely related to hopping frequency. Additional mass significantly increased ankle dorsiflexion and contact duration but did not significantly affect hip flexion, knee flexion, or vertical stiffness. The differential response of vertical stiffness to hopping frequency and added mass was consistent with predictions based on a mass-spring model. The interactive effect of frequency and added mass on the kinematics of the lower extremity and contact period were consistent with earlier studies of the independent effects of hopping frequency and added mass.     

Finger inter-dependence: linking the kinetic and kinematic variables

We studied the dependence between voluntary motion of a finger and pressing forces produced by the tips of other fingers of the hand. Participants moved one of the fingers (task finger) of the right hand trying to follow a cyclic, ramp-like flexion-extension template at different frequencies. The other fingers (slave fingers) were restricted from moving; their flexion forces were recorded and analyzed. Index finger motion caused the smallest force production by the slave fingers. Larger forces were produced by the neighbors of the task finger; these forces showed strong modulation over the range of motion of the task finger. The enslaved forces were higher during the flexion phase of the movement cycle as compared to the extension phase. The index of enslaving expressed in N/rad was higher when the task finger moved through the more flexed postures. The dependence of enslaving on both range and direction of task finger motion poses problems for methods of analysis of finger coordination based on an assumption of universal matrices of finger interdependence.     

Bimanual Lifting: Do Fingertip Forces Work Independently or Interactively?

Bimanual coordination is a commonplace activity, but the consequences of using both hands simultaneously are not well understood. The authors examined fingertip forces across 4 experiments in which participants undertook a range of bimanual tasks. They first measured fingertip forces during simultaneous lifts of 2 identical objects, noting that individuals held the objects with more force bimanually than unimanually. They then varied the mass of the objects held by each hand, noting that when both hands lifted together performance was equivalent to unimanual lifts. The authors next measured one hand's static grip force while the other hand lifted an object. They found a gradual reduction of grip force throughout the trial, but once again no evidence of one hand influencing the other. In the final experiment the authors tested whether tapping with one hand could influence the static grip force of its counterpart. Although the authors found no changes in static grip force as a direct consequence of the other hand's actions, they found clear differences from one task to the other, suggesting an effect of task instruction. Overall, these results suggest that fingertip forces are largely independent between hands in a bimanual lifting context, but are sensitive to different task requirements.     

Improvement in gross motor performance between 3 and 5 years of age

This study examined gross motor performance of 101 typically developing children between 3 and 5 years of age (48 boys, 53 girls, M age = 3.9 yr., SD = 0.5). All children performed 7 different gross motor tasks which were rated on a 5-point scale. Age and sex were assessed by an ordinal-logistic model, and odds ratios were calculated for each task using age and sex as covariates. For standing on one leg, walking on a beam, hopping on one leg, running, and taking stairs, statistically significant age differences were found, while for rising and jumping down, none were apparent. Mean motor performance did not differ between boys and girls on the tasks. The older the children were, the better they performed on the tasks.     

Knowledge and imagery of contractile mechanisms do not improve muscle strength

Improving performance in strength tasks requires modifications charateristic of motor skill learning, such as more efficacious motor-unit firing behavior. Because domain-specific knowledge is integral to learning and performing motor kills, the present purpose was to examine selected factors of strength-specific knowledge and effects they might have on acquiring strength. Following baseline testing for maximal strength on a knee-extension task, participants were matched by sex and strength and placed into control (n=8) and treatment (n=8) groups. Quadriceps muscle electromyographic data were also collected. The treatment group underwent two educational sessions detailing muscle physiology, neural control of muscle force, and imagery training using this knowledge. The control group underwent two educational sessions about health and fitness. Following the educational sessions the participants were retested for strength. Analysis indicated that the education and imagery treatment had no effect on strength, nor did electromyographic measures indicate that the treatment group benefitted from intervention. It was concluded that the knowledge was simply not relevant to knee extension-force production or that use of the knowledge involved a disadvantageous internal focus of attention away from relevant task demands.     

Development of unimanual versus bimanual task performance in an isometric task

Sixty-three children between 5 and 12 years of age and 15 adults performed a unimanual and a bimanual isometric force task. The performance of the preferred hand in the unimanual task was compared to the performance of the preferred hand in the bimanual task. It was hypothesized that in the bimanual task the absolute error will be higher, there will be more irregularity and the participants will need more time due to the additional effort from the central nervous system, especially with respect to the communication between the hemispheres. Furthermore, in younger children bimanual force variability was expected to be higher due to developmental aspects concerning callosal maturation and attention. It was found that with respect to force generation the preferred hand was not affected by bilateral isometric force generation, but with respect to force regulation it was. The coefficient of variation (CV) of the force was 34% larger in the bimanual task as compared to the unimanual task. For the time to target force, the increase was 28%. With repetition of the trials the CV decreased in the bimanual task, but only in the youngest age group. During development there was no change in absolute error, yet there was a major reduction in force variability in the bimanual task. It is suggested that improvement in interhemispheric communication and in the ability to focus attention plays a role in the decrease in variability with age.     

Effect of knee extensors muscles fatigue on bilateral force accuracy,variability, and coordination

The aim of this study was to test the effect of fatigue of the knee extensors muscles on bilateral force control accuracy, variability, and coordination in the presence and absence of visual feedback. Twenty-two young physically active subjects (18 males, 4 females) were divided into two groups and performed 210 submaximal sustained bilateral isometric contractions of knee extensors muscles with and without visual feedback. One group performed a symmetrical task—both legs were set at identical positions (60° knee flexion)—while the other group performed an asymmetrical task (60° and 30° knee flexion). We used the framework of the uncontrolled manifold hypothesis to quantify two variance components: one of them did not change total force (V_UCM), while the other did (V_ORT). Performance of bilateral isometric contractions reduced voluntary and electrically induced force without changes in bilateral force control variability and accuracy. Bilateral force production stability and accuracy were higher in both tasks with visual feedback. Synergistic (anti-phase) structure of force control between the lower limbs occurred and the values of synergy index were higher only during the performance of the asymmetrical task with visual feedback. In addition, greater bilateral force control accuracy was observed during the performance of the asymmetrical task (with and without visual feedback), despite no differences in within-trial variability of both tasks.     

Role of arms in somersaulting from compliant surfaces: a simulation study of springboard standing dives

The role of arms in compliant-surface jumping for maximizing backward somersault rotations is studied using multi-segment models and is applied to springboard diving. The surface (springboard) is modeled by a rigid bar with a rotational spring with a hinged end and point mass at the tip. Planar four- and five-segment human models are used (with the fifth segment representing the arms) and are driven by torque actuators at the ankle, knee, hip, and shoulder. Each joint torque is the product of maximum isometric torque and three variable functions depending on instantaneous joint angle, angular velocity, and activation level, respectively. Movement simulation starts from a balanced initial posture and ends at jump takeoff. The objective is to find joint torque activation patterns during board contact so that the number of backward rotations in flight is maximized. Kinematic differences in jumps with and without arms are mainly in smaller takeoff vertical velocity and more flexed knee and hip in the former. In both jumps, joint torque/activations are similar in their minor flexion-full extension patterns. Maximum hip torque is larger with arms but maximum knee torque is larger without arms. Except at the knee, more joint work can be done with arm swing. Total angular momentum is increased considerably by arm motion because of its remote contribution. Consequently segment remote contributions to total angular momentum are much larger in jumping with arms. Shoulder strength helps generate angular momentum only to a certain limit. If more work is used to generate horizontal velocity away from the board, the amount of total angular momentum is reduced.     

Postural control in children with and without neurofibromatosis type 1

Previous research has evaluated the motor proficiency of children with neurofibromatosis type 1 (NF1) and found delays on the balance subtest. However the balance subtest was found to have low sensitivity for identifying balance impairments. This study examines the differences in postural control between children with NF1 and peers with typical development using a force plate. A single limb stance test on a force plate was completed for all participants. The force plate variables, center of pressure maximum distance in the anterior/posterior direction (COPmax A/P) and center of pressure velocity (COPvel A/P) were compared between groups. The NF1 group’s performance was significantly poorer than the control group in both COPmax A/P (p = .01) and COPvel A/P (p = .01). When separated into specific age ranges, only the children in the NF1 group between 5 and 12 years of age demonstrated statistically significant differences in the COP variables. The COP variables for the 13- to 18-year-old group were not significantly different. These results indicate that young children with NF1 have poor postural control. However, postural control appears to improve with maturation.     

Bimanual and Unimanual Convergent Goal-Directed Movement Times

Three experiments are reported, investigating the effects of using 1 or 2 hands when making convergent low index of difficulty (ID) and visually controlled movements (2 hands meeting together). The experiments involved movements in four different cases—a probe held in the right hand and moved to a target held in the stationary left hand, vice versa of this arrangement, both hands moving with the probe in the right hand and target in the left hand, and vice-versa of this arrangement. Experiments were the standard Fitts’ paradigm, moving a pin into a hole and a low-ID task. In Fitts’ task, 2-hand movements were faster than 1 hand only at higher IDs; this was also the case in the pin-to-hole transfer task and the movement times were lower when the pin was held in the preferred hand. Movements made with low ID showed a small effect of 1- or 2-handed movements, with the effective amplitude of the movement being reduced by about 20% when 2 hands were used.     

Examining the response programming function of the Quiet Eye: Do tougher shots need a quieter eye?

Support for the proposition that the Quiet Eye (QE) duration reflects a period of response programming (including task parameterisation) has come from research showing that an increase in task difficulty is associated with increases in QE duration. Here, we build on previous research by manipulating three elements of task difficulty that correspond with different parameters of golf-putting performance; force production, impact quality and target line. Longer QE durations were found for more complex iterations of the task and furthermore, more sensitive analyses of the QE duration suggest that the early QE proportion (prior to movement initiation) is closely related to force production and impact quality. However, these increases in QE do not seem functional in terms of supporting improved performance. Further research is needed to explore QE’s relationship with performance under conditions of increased difficulty.     

Are hand-grip and knee extension strength reflective of a common construct?

Grip and knee extension strength have each been used to characterize muscle strength. Whether grip and knee extension strength reflect a common construct was investigated. Bilateral isometric grip and knee extension strength measures obtained by dynamometry were retrieved from the records of 34 adults who were at least 60 years of age (M = 80.2 yr., SD = 8.1) and had diverse non-focal diagnoses or problems. Relations between measurements were examined using Pearson correlations, Cronbach's alpha, and factor analysis. Pearson correlations (r = .55 to .89), Cronbach's alpha (.88), and factor analysis (loadings .85 to .91) all suggest that grip and knee extension strength reflect a common construct. Either grip or knee extension strength, therefore, may be adequate to characterize limb muscle strength in older adults who are receiving physical therapy for diverse non-focal diagnoses or problems. Nevertheless, the measurement of grip strength may be preferred because it is easier.