The rate of force relaxation scaling factor is highly sensitive to detect upper and lower extremity motor deficiencies in mildly affected people with multiple sclerosis.

BACKGROUND: The motor symptoms affecting upper and lower extremity functioning in people with multiple sclerosis (PwMS) are considered the cardinal symptoms of multiple sclerosis. There is still a need for outcome measures that can sensitively evaluate these symptoms. We aimed to investigate the sensitivity of the isometric outcomes (maximum force; Fmax, maximum rate of force development; RFDmax, rate of force development scaling factor; RFD-SF, and rate of force relaxation scaling factor; RFR-SF) and standard clinical tests (9-hole peg test; 9HPT and timed 25-feet walk test; T25FW) in detecting the upper and lower extremity motor deficiencies in PwMS and also in a subgroup of mildly affected PwMS whose performance in standard clinical tests were similar to controls. METHODS: Twenty-nine PwMS (age: 47.9 (8.6) years, relapsing-remitting type, expanded disability status scale: 2.5 (1.5)) and their age- and gender-matched controls completed an identical testing protocol in the upper (grip force muscles) and lower (knee extensors) extremities. For each extremity, we assessed Fmax, RFDmax, RFD-SF, and RFR-SF. Additionally, participants completed standard clinical tests for the evaluation of upper- (9HPT) and lower-extremity (T25FW) function. Comparisons were made between controls and PwMS 1) using all study participants and 2) including only mildly affected PwMS whose performance in standard functional tests was comparable to controls. Independent sample t-tests were utilized to compare groups, with a p-value set at 0.01 to correct for multiple comparisons. P-values and effect sizes were used to evaluate the sensitivity of the outcome measures in detecting group differences. RESULTS: Our results indicate that most isometric outcomes and standard functional tests were sensitive in detecting motor deficiencies in both upper and lower extremities between groups (p<0.001). Among participants, 16 PwMS in 9HPT and 11 PwMS in T25FW demonstrated performance similar to that of the control group (9HPT: 18.85 (2.20) s vs 17.81 (2.19) s; p=0.19) and (T25FW: 3.60 (0.42) s vs 3.58 (0.29) s; p=0.92). The results of the comparisons between mildly affected PwMS and their controls indicate that RFR-SF is the only sensitive isometric outcome to detect differences between groups in the upper (-8.24 (0.76) 1/s vs -8.93 (0.6) 1/s; p=0.008) and lower extremity (-5.86 (1.13) 1/s vs -7.71 (1.11) 1/s; p<0.001). CONCLUSION: The rate of force relaxation scaling factor, which assesses the ability to rapidly relax muscle forces after quick contractions, demonstrates high sensitivity in detecting motor deficiencies in PwMS, even when the current standard clinical outcomes fail to detect these differences. Our findings emphasize the importance of future randomized controlled trials focusing on rehabilitative and therapeutic interventions that specifically target muscle force relaxation to enhance motor functioning in PwMS.

The impact of postexercise blood flow restriction on local muscle endurance of a remote limb.

BACKGROUND: Studies have examined the influence of postexercise blood flow restriction as a mechanism to activate muscle afferents and assess nonlocal muscle fatigue. Although these studies have assessed fatigue during maximal contractions, less is known about how these afferents may impact submaximal local muscle endurance, which was the purpose of the present study. METHODS: Individuals completed two testing visits which involved completing a set of elbow flexion exercises to volitional failure on the nondominant followed by the dominant arm. During both trials, a pneumatic cuff was placed at the top of the nondominant arm before exercise. This cuff was inflated to either 0% (control) or 70% (experimental) of the individual's arterial occlusion pressure immediately after the set was completed. We then evaluated how this impacted local muscle endurance of the dominant arm using a Bayesian paired samples t-test with an uninformed prior width of 0.707 centred on 0. RESULTS: A total of 36 individuals completed the study (18 females). There was a greater discomfort present in the experimental trial when compared to the control trial (control: 4.5 standard deviation [SD]: 2.4); experimental: 5.8 [SD: 1.9]; BF10 = 61.46), but there were no differences in repetitions completed on the dominant arm (control: 43 [SD: 9], experimental: 43 [SD: 10]; BF10 = 0.179). CONCLUSION: Applying blood flow restriction postexercise induced sensations of discomfort but did not alter the local muscle endurance of the contralateral limb. These results suggest that increasing the activation of muscle afferents does not appear to alter the submaximal muscle endurance of a remote limb.

Isometric tests to evaluate upper and lower extremity functioning in people with multiple sclerosis: reliability and validity.

BACKGROUND: Both upper and lower extremity motor symptoms are common in people with multiple sclerosis (PwMS) and there is a need to develop objective, reliable, and valid outcome measures. The aim of this study was to evaluate the reliability and external validity of the standard and novel isometric tests in the assessment of neuromuscular functioning in both upper (grip force; GF) and lower (knee extensors; KE) extremities in PwMS. METHODS: Twenty-nine relapsing-remitting PwMS (Expanded Disability Status Scale (EDSS)<6) completed isometric and functional tests in upper (grip force) and lower (knee extension) extremity in two separate visits. Isometric testing included maximum force (maxF), maximum rate of force development (maxRFD), and our recently developed novel brief force pulse protocol (BFP). The dependent variables of BFP included rate of force development and relaxation scaling factors (RFD-SF and RFR-SF), which quantifies an individual's ability to scale the rates of force development and relaxation with the magnitude of force pulse produced. PwMS also completed functional tests of upper (9-hole peg (9HPT), finger tapping (FTT)) and lower extremity (25-ft walk test (T25WT), timed up and go (TUG), 5-time sit-to-stand (5StS), and Multiple Sclerosis Spasticity Scale (MSSS-88)). RESULTS: Most isometric outcome measures had high reliability (ICCs>0.87 and CVs<12%). In GF, both RFD-SF and RFR-SF had significant associations with 9HPT and FTT (r's between 0.49-0.55, p<0.05). In KE, while maxF, maxRFD, and RFD-SF were moderately correlated to some of the functional tests, the strongest correlations were observed for the RFR-SF (T25FW, r=0.71; TUG, r=0.60; 5StS, r=0.47; MSSS-88, r=0.60, and EDSS, r=0.71). Multiple linear regression analysis indicated that RFD-SF is the only predictor for 9HPT and RFR-SF is the only predictor of walking speed among the studied variables. CONCLUSIONS: BFP protocol provides highly reliable and relevant outcome measures to evaluate both upper and lower extremity functioning in PwMS. Specifically, the ability to relax muscle forces quickly after a quick force production highly contributes to walking speed in PwMS.

The Effect of Increasing Blood Flow Restriction Pressure When the Contractions Are Already Occlusive.

CONTEXT: Blood flow restricted exercise involves the use of external pressure to enhance fatigue and augment exercise adaptations. The mechanisms by which blood flow restricted exercise limits muscular endurance are not well understood. OBJECTIVE: To determine how increasing blood flow restriction pressure impacts local muscular endurance, discomfort, and force steadiness when the contractions are already occlusive. DESIGN: Within-participant, repeated-measures crossover design. SETTING: University laboratory. PATIENTS: A total of 22 individuals (13 males and 9 females). INTERVENTION: Individuals performed a contraction at 30% of maximal isometric elbow flexion force for as long as possible. One arm completed the contraction with 100% of arterial occlusion pressure applied, while the other arm had 150% of arterial occlusion pressure applied. At the end of the protocol, individuals were asked to rate their perceived discomfort. MAIN OUTCOME MEASURES: Time to task failure, discomfort, and force steadiness. RESULTS: Individuals had a longer time to task failure when performing the 100% arterial occlusion condition compared with the 150% arterial occlusion pressure condition (time to task failure = 82.4 vs 70.8 s; Bayes factors = 5.77). There were no differences in discomfort between the 100% and 150% conditions (median discomfort = 5.5 vs 6; Bayes factors = 0.375) nor were there differences in force steadiness (SD of force output 3.16 vs 3.31 N; Bayes factors = 0.282). CONCLUSION: The results of the present study suggest that, even when contractions are already occlusive, increasing the restriction pressure reduces local muscle endurance but does not impact discomfort or force steadiness. This provides an indication that mechanisms other than the direct alteration of blood flow are contributing to the increased fatigue with added restrictive pressure. Future studies are needed to examine neural mechanisms that may explain this finding.

Acceptability and effectiveness of a novel cycling training on the parkinsonian motor and psychiatric symptoms in individuals with schizophrenia: A pilot study.

BACKGROUND: Recent evidence suggests that high-speed, low-resistance stationary cycling training (termed as speedwork) alleviates motor symptoms in people with Parkinson's disease. Similar motor symptoms commonly exist in people with schizophrenia (Sz); however, they were neglected in the previous literature. OBJECTIVES: Our objective was to evaluate if speedwork could also be used as a strategy to improve parkinsonian motor symptoms in Sz. We aimed 1) to evaluate the adherence and acceptability of speedwork in Sz, 2) to assess test-retest reliability of the motor assessments that are novel to Sz research, 3) to evaluate the effectiveness of speedwork in improving parkinsonian motor, and 4) psychiatric symptoms in Sz. METHODS: Ten Sz outpatients with concurrent parkinsonian motor symptoms completed 12 sessions (2 sessions/week) of speedwork training. Participants were evaluated on motor functioning and psychiatric symptom severity twice before (double baseline) and twice after (post-completion and 6-wk follow-up) the speedwork training. RESULTS: The adherence to speedwork was high (92 %) and the results of exercise acceptability questionnaire indicate participants found various domains of exercise highly acceptable (overall average 4.49/5). There were improvements in various domains of motor symptoms including, walking speed, functional mobility, static and dynamic balance, and upper extremity motor function after the completion of training (all p < 0.025), with many of these improvements remaining at the 6-wk follow-up. Moreover, there was evidence for improvement in positive psychotic symptoms after the completion of speedwork (p < 0.025). CONCLUSIONS: Speedwork training could be an acceptable and effective strategy to improve motor and psychiatric symptoms in Sz.

The relationship between changes in distal tibiofibular joint congruence and clinical and functional results in the short-term follow-up of patients operated on for ankle fracture.

BACKGROUND: The effects of changes in distal tibiofibular joint (DTFJ) congruence on clinical and functional outcomes are unclear in patients operated on for ankle fractures. The present study aims to evaluate the relationship between changes in DTFJ congruence and clinical and functional outcomes in the short-term follow-up of the patients operated on for ankle fractures. METHODS: In this study, hospital records of patients who were operated on for ankle fractures were retrospectively analyzed. The data of patients who underwent bilateral ankle computed tomography scans at least 18 months after surgery were used. DTFJ congruence was evaluated using four methods. Method 1: the distance between the most prominent anterior points of the tibia and fibula (anterior incisura [AI]) and that between the most prominent posterior points of the tibia and fibula (posterior incisura [PI]) were measured. Method 2: the direct anterior (DA) and direct posterior (DP) distances were measured based on perpendicular lines drawn from the most prominent anterior and posterior points of the longitudinal axis of the fibula to the tibia, respectively, and a direct translation (DT) distance was measured based on a perpendicular line drawn to the DA from the most prominent anterior point of the tibia. Method 3: the angle between a line connecting the most anterior and posterior points of the tibia and a line connecting the most anterior and posterior points of the fibula (rotational angle [RA]) was measured. The differences in distances and angles (dAI, dPI, dDA, dDP, dDT, and dRA) between the injured and non-injured sides were calculated in the first three methods. Method 4: any rotational/translational incongruency on the injured side was subjectively reported. The American Orthopedic Foot and Ankle Society (AOFAS) ankle-hindfoot scale, Olerud-Molander Ankle Score (OMAS), and Visual Analog Scale (VAS) were used for clinical and functional evaluations. RESULTS: Thirty patients (18 males and 12 females; mean age, 43.3 [range, 20-78 years] years) were included in this study. The average follow-up was 37.6 (range, 18-54 months) months. Negative correlations were detected between dDA and the AOFAS-pain subscale (r=-0.37; p=0.04), between dDP and the OMAS (r=-0.57; p=0.01), and between dDT and the AOFAS-pain, AOFAS-function, and OMAS (r=-0.55 p=0.01; r=-0.40; p=0.03; r=-0.39; p=0.04, respectively). CONCLUSION: Changes in dDA, dDP, and dDT values affect the clinical and functional outcomes. These parameters should be provided in accordance with the anatomy of the patient during the reduction of the DTFJ to achieve better outcomes.

Can the complications of distal locking be prevented with a new nail that offers a novel locking technique in the treatment of humeral shaft fractures?

OBJECTIVES: This study aims to investigate whether complications related to distal locking can be prevented with InSafeLOCK® nail in the treatment of humeral shaft fractures. PATIENTS AND METHODS: Hospital records of 31 patients (15 males, 16 females; mean age 54.4±10.1 years; range, 20 to 86 years) treated with InSafeLOCK® nail for humeral shaft fractures were investigated retrospectively between February 2016 and January 2019. Arbeitsgemeinschaft für Osteosynthesefragen (AO) classification was used to determine the type of fracture. During the implementation, the elapsed time for distal locking was investigated. Complications encountered during both implementation and postoperative follow-up were investigated. RESULTS: Fourteen of the fractures were type A, 12 were type B, and five were type C. The mean follow-up time was 18.2 (range, 6 to 30.5) months. The mean duration for distal locking was 2.1 (range, 1.2 to 3.1) minutes. In one (3.2%) patient, cortical penetration occurred at the anterior cortex of the humerus at distal to the nail. In one patient, nail breakage occurred at the distal part of the nail. In one patient, rotational instability occurred due to screw loosening. CONCLUSION: InSafeLOCK® humeral nail is safe when applied with the recommended technique. It can easily be applied without damaging the veins, nerves or other soft tissues around the elbow due to the internal distal locking feature; furthermore, there is no need to use fluoroscopy or targeting guide. Thus, it is possible to avoid complications that may occur during and after distal locking in conventional intramedullary nail implementations.

Age- and Sex-Related Differences in the Maximum Muscle Performance and Rate of Force Development Scaling Factor of Precision Grip Muscles.

The aim of this study was to explore the effects of age and sex on the rate of force development scaling factor (RFD-SF) and maximum performance (i.e., maximum grip force [GFMax] and maximum rate of grip force development [RGFDMax]) of precision handgrip muscles. Sixty-four subjects, allocated in four groups according to their age and sex, were asked to hold an instrumented handle with the tip of the digits and perform two tests: maximum voluntary contraction and RFD-SF tests. In the maximum voluntary contraction test, GFMax and RGFDMax were assessed. In the RFD-SF test, the subjects generated quick isometric force pulses to target amplitudes varying between 20% and 100% of their GFMax. The RFD-SF and R2 values were obtained from the linear relationship between the peak values of the force pulses and the corresponding peak values of the rate of force development. Younger adults and males produced higher GFMax and RGFDMax and presented higher R2 and RFD-SF than older adults and females, respectively. No correlations between GFMax and RFD-SF and between RGFDMax and RFD-SF were observed.

Rate of force development and relaxation scaling factors are highly sensitive to detect upper extremity motor impairments in multiple sclerosis.

OBJECTIVE: Clinical assessment of upper extremity in multiple sclerosis is mainly limited to 9-hole peg test (9-HPT), which is commonly criticized due to its limited sensitivity. There is a need for sensitive outcome measures for the assessment of motor symptoms in individuals with multiple sclerosis (iMS). We evaluated our recently developed brief force pulse protocol to simultaneously quantify the motor control of hand function and neuromuscular quickness in iMS. Additionally, we compared the sensitivity of the studied outcome measures with 9-HPT in detecting the differences between iMS and controls. METHODS: Twelve iMS and 12 controls grasped a grip- (GF; perpendicular force) and load-force (LF; tangential force) measuring handle and produced around 100 isometric LF pulses to various submaximal levels by pushing down on it as quickly as possible, followed by quick relaxation. The GF-LF ratio quantified the motor control of hand function. The slopes of linear regressions between peak forces and corresponding peak rates of force development (rate of force development scaling factor; RFD-SF) and relaxation (rate of force relaxation scaling factor; RFR-SF) quantified the control of neuromuscular quickness. RESULTS: All of the selected variables were different between groups (all p-values < .05), and the effect sizes obtained from RFD-SF (d = 2.87) and RFR-SF (d = 1.93) were larger than the effect sizes obtained from 9-HPT (d = 1.07). CONCLUSION: Measures of neuromuscular quickness are more sensitive to detect disease related differences than 9-HPT and, therefore, can be used as a tool in clinical and rehabilitative settings to objectively evaluate therapeutic interventions and disease progression in iMS.

A novel method to assess rate of force relaxation: reliability and comparisons with rate of force development across various muscles.

PURPOSE: The ability to generate quick submaximal muscle forces followed by quick relaxations is essential for various athletic and daily tasks. While force generation has been studied extensively, the studies of force relaxation are scarce. Therefore, we aimed to develop the rate of force relaxation scaling factor (RFR-SF) as a kinetic variable to assess the ability to relax submaximal muscle forces quickly. METHODS: Thirteen young adults performed rapid isometric force pulses to various submaximal levels in two different sessions. We compared RFR-SF with rate of development scaling factor (RFD-SF) in grip force muscles (GF), elbow (EE), and knee extensors (KE) and tested its reliability. Both RFD-SF and RFR-SF were calculated as the slopes of the linear relationship between peak forces and the corresponding peak rates of force development and relaxation, respectively. RESULTS: RFR-SFs were mainly different among the tested muscle groups (GF 8.22 ± 0.76 1/s; EE 7.64 ± 0.92 1/s; KE 6.01 ± 1.75 1/s) and there was no correlation among them (all p > 0.05). Within each tested muscle group, RFR-SF was lower than RFD-SF (GF 9.29 ± 1.05 1/s; EE 10.75 ± 0.87 1/s; KE 9.66 ± 0.89 1/s; all p < 0.001). The reliability of RFR-SF was moderate to good across the tested muscles (ICCs between 0.54 and 0.76 and all CVs < 15%). CONCLUSION: The RFR-SF is a clinically relevant kinetic variable that can reliably quantify the ability to relax a muscle force quickly. Future studies should assess both RFD-SF and RFR-SF as they represent different properties of the neuromuscular system.

Methodological considerations in the calculation of the rate of force development scaling factor.

OBJECTIVE: Within this methodological study, we aimed to explore the effects of seven different commonly applied routines for rate of force development (RFD) calculation on the calculation of rate of force development scaling factor (RFD-SF) and r 2 and the between session reliability of RFD-SF in three different muscle groups. APPROACH: We tested grip force muscles, elbow extensors and knee extensors of 13 healthy subjects asking them to produce around 120 rapid isometric force pulses per muscle to varying submaximal amplitudes. Then, we applied different filtering and analysis procedures, such as different filtering cut-off frequencies (no filter, 5 Hz cut-off, 10 Hz cut-off) and time windows during which RFD was calculated (0-50 ms, 0-75 ms, 0-100 ms and time from onset of contraction to peak force (PF) value). RFD-SF and r 2 were obtained from the relationship between the PF and the corresponding RFD. RESULTS: Our results showed that the magnitude of the calculated RFD-SF and r 2 values significantly differed among different RFD calculation methods (p < 0.0005), but that r 2 was high in most applied methods (RFD-SF ranged between 4.6 and 17.7, while r 2 ranged between 0.63 and 0.98). Regardless of the tested muscle group and applied method to calculate RFD, the reliability of the calculated RFD-SF was moderate (0.5 < ICC3,1 < 0.75) to good (ICC3,1 > 0.75). The highest r 2, highest ICC, lowest SEM% and MDD% were observed in case of RFD calculated during first 100 ms and when cut-off filter at 5 Hz was applied, indicating those two methods as the most appropriate ones. SIGNIFICANCE: Our study contributes to the establishment of methodological suggestions that will help in maximizing the reliability of RFD-SF measurements, collecting normative data, and comparing results among different populations and lab settings.

Effects of a low-resistance, interval bicycling intervention in Parkinson's Disease.

Previous studies have shown that people with Parkinson's disease (PD) benefit from a variety of exercise modalities with respect to symptom management and function. Among the possible exercise modalities, speedwork has been identified as a promising strategy, with direct implications for the rate and amplitude of nervous system involvement. Considering that previous speed-based exercise for PD has often been equipment, personnel and/or facility dependent, and often time intensive, our purpose was to develop a population-specific exercise program that could be self-administered with equipment that is readily found in fitness centers or perhaps the home. Fourteen individuals with PD (Hoehn-Yahr (H-Y) stage of 3.0 or less) participated in twelve 30-min sessions of low-resistance interval training on a stationary recumbent bicycle. Motor examination section of the Unified Parkinson's Disease Rating Scale (UPDRS), 10-meter walk (10mW), timed-up-and-go (TUG), functional reach, four-square step test (4SST), nine-hole peg test (9HPT) and simple reaction time scores all exhibited significant improvements (p < 0.05). These results add further support to the practice of speedwork for people with PD and outline a population-amenable program with high feasibility.

Simultaneous assessment of hand function and neuromuscular quickness through a static object manipulation task in healthy adults.

Both hand function [as seen through the coordination between grip force (GF) and load force (LF)] and the ability to produce a submaximal force quickly (i.e., neuromuscular quickness) are two important qualities of motor function that could be seriously affected by the presence of neurological diseases. Therefore, their quantitative assessment is very important in clinical settings. Within this study, we aimed to develop, standardize, and measure the within-session reliability of a clinically meaningful test that assesses both hand function and neuromuscular quickness simultaneously. Thirteen healthy young adults produced around 90 rapid isometric LF pulses to varying submaximal magnitudes by either pulling down or pulling up on an externally fixed GF- and LF-measuring device. Results revealed high indices of force coordination (i.e., GF scaling as assessed by GF/LF and GF coupling as assessed by maximum cross-correlation between GF and LF) in both force directions, while GF coupling was higher in downward than in upward direction (p < 0.001). Regarding the indices of neuromuscular quickness (i.e., the regression parameters obtained from the relationship between peak force and it's rate of development and half-relaxation time), results, in general, revealed a higher slope (named as rate of force development scaling factor; p < 0.01), similar R 2 (p > 0.05), and shorter half-relaxation time (p < 0.05) for LF than for GF. Furthermore, all of the selected variables showed moderate to excellent within-session reliability with only 45 pulses. Findings suggest that brief force production tasks should be further evaluated as clinical tests of hand function and neuromuscular quickness in various populations.

High-Speed Cycling Intervention Improves Rate-Dependent Mobility in Older Adults.

PURPOSE: The aim was to determine the feasibility of a 6-wk speed-based exercise program that could be used to initiate new exercise behaviors and to improve rapid movement in older adults approaching frailty. METHODS: The intervention group included 14 older adults (3 males and 11 females; mean ± SD, age = 70 ± 7.6 yr, height = 1.6 ± 0.11 m, mass = 76.8 ± 12.0 kg, body mass index = 27.7 ± 4.7 kg·m). The control group included 12 older adults (6 males and 6 females; mean ± SD, age = 69.2 ± 6.9 yr, height = 1.7 ± 0.09 m, mass = 78.2 ± 10.9 kg, body mass index = 25.3 ± 2.7 kg·m). Subjects included active older adults, including regular exercisers, but none were engaged in sports or exercises with an emphasis on speed (e.g., cycling spin classes or tennis). Stationary recumbent cycling was selected to minimize fall risk, and low pedaling resistance reduced musculoskeletal and cardiovascular load. Two weekly 30-min exercise sessions consisted of interval training in which subjects pedaled at preferred cadence and performed ten 20-s fast cadence intervals separated by 40 s of active recovery at preferred cadence. RESULTS: Significant group-time interactions (P < 0.05) supported a 2-s improvement in the timed up and go test and a 34% improvement in rapid isometric knee extension contractions in the exercise group but not in controls. Central neural adaptations are suggested because this lower extremity exercise program also elicited significant improvements in the untrained upper extremities of the exercise group (elbow extension rate of force development scaling factor and Nine-Hole Peg Test, P < 0.05). CONCLUSION: These results demonstrate that a relatively low dose of speed-based exercise can improve neuromuscular function and tests of mobility in older adults. Such a program serves as a sensible precursor to subsequent, more vigorous training or as an adjunct to a program where a velocity emphasis is lacking.

Effects of Unilateral Muscle Fatigue on Performance and Force Coordination in Bimanual Manipulation Tasks.

We examined the effects of unilateral muscle fatigue on the performance and coordination of grip (GF; normal component acting between the hand and object) and load force (LF; tangential component) in bimanual manipulation tasks, as well as the associated lateral differences. Eleven participants performed various symmetric bimanual tasks either without fatigue, or after fatiguing the GF producing muscles of either the nondominant or dominant hand. The GF/LF ratio of the fatigued and nonfatigued hand decreased and increased, respectively, while the neither the effects of fatigue on the task performance and GF-LF coordination, nor the lateral differences were revealed. The lack of the fatigue associated effects on most of the tested variables typically observed from unimanual tasks could be explained by bimanual assimilation. The findings also suggest that in daily life switching to bimanual tasks when one hand becomes fatigued could be beneficial regarding preserving the high level of both the manipulation performance and force coordination.

Mid-term radiological and clinical results of incomplete triple pelvic osteotomy.

OBJECTIVE: The aim of this study was to assess clinical and radiological results of incomplete triple pelvic osteotomy in acetabular dysplasia. PATIENTS AND METHODS: Twenty-six hips of 24 patients (5 males, 19 females) treated with incomplete triple pelvic osteotomy by a single surgeon from February 1995 to October 2001 were retrospectively reviewed at an average follow-up time of 12 years. The mean age at the time of surgery was 21.6 years (range: 14-41). Radiological evaluation was based on the central edge angle, acetabular angle, acetabular index, acetabular head index and lateralisation. Clinical and radiological scoring was performed using the Harris scoring system, Ömeroglu scoring system and the Tönnis criteria for osteoarthritis. RESULTS: There was significant improvements in all of the radiological parameters with 88.5% good radiological results, 96.2% excellent clinical results, no significant progression to osteoarthritis and no need for conversion to total hip arthroplasty. The rate of major complication was 11%. Retroversion was seen in 15.4% of the hips. CONCLUSION: Our results support the use of incomplete triple pelvic osteotomy as a safe choice in the treatment of acetabular dysplasia as it offers clinical and radiological benefits and contributes to the prevention of osteoarthritis. LEVEL OF EVIDENCE: Level IV, therapeutic study.

Immediate effects of high-speed cycling intervals on bradykinesia in Parkinson's disease.

There is growing evidence that speed-based exercise training benefits people with Parkinson's disease (PD). The present study investigates the effects of a single session of volitional, high-speed cycling intervals on a battery of timed functional tests selected for their relevance to the symptom of bradykinesia. Ten subjects with PD (Hoehn-Yahr stage ≤ 3.0) participated in a familiarization session and three test sessions. Functional testing occurred before and after 30 minute sessions in which subjects performed no exercise (NO), pedaled at their preferred cadence (PC), or performed 20, 15-second intervals of high-speed low-resistance cycling (HS-LR). In addition to testing the exercise effects in a within-subjects design, we provide test-retest reliability data, minimal detectable change scores, and correlations among the selected functional tests. Despite the relatively low dose of speed-based exercise, HS-LR elicited significant (p < 0.05) improvements in the four square step test and 10 m walk test. Excepting reaction times, there was high reliability and adequate sensitivity to detect moderate and small differences. Strong correlations among tests of mobility inform the future selection of measures in the experimental design. In addition to what is known about continuous exercise sessions involving high-speed exercise, the present results suggest that brief intervals of HS-LR bicycling are promising and should be examined in a longer duration exercise program.

Selective effects of arm proximal and distal muscles fatigue on force coordination in manipulation tasks.

Effects of muscle fatigue on force coordination and task performance of various manipulation tasks are explored. Grip force (GF; normal force component acting at the digits-object contact area) and load force (LF; tangential component that lifts and holds objects) were recorded prior to and after fatiguing the distal (DAM; i.e., GF producing) and proximal arm muscles (PAM; LF producing). Results reveal a deterioration of GF scaling (i.e., averaged GF-LF ratio), GF-LF coupling (their correlation), and task performance (ability to exert a prescribed LF pattern) associated with DAM, but not PAM fatigue. Deteriorated force coordination clearly increases the likelihood of dropping an object; however, the observed selective effects of DAM and PAM fatigue represent a novel finding deserving of further research.

Force control in manipulation tasks: comparison of two common methods of grip force calculation.

We compared two standard methods routinely used to assess the grip force (GF; perpendicular force that hand exerts upon the hand-held object) in the studies of coordination of GF and load force (LF; tangential force) in manipulation tasks. A variety of static tasks were tested, and GF-LF coupling (i.e., the maximum cross-correlation between the forces) was assessed. GF was calculated either as the minimum value of the two opposing GF components acting upon the hand-held object (GFmin) or as their average value (GFavg). Although both methods revealed high GF-LF correlation coefficients, most of the data revealed the higher values for GFavg than for GFmin. Therefore, we conclude that the CNS is more likely to take into account GFavg than GFmin when controlling static manipulative actions as well as that GFavg should be the variable of choice in kinetic analyses of static manipulation tasks.