Tai Chi improves balance and mobility in people with Parkinson disease

This pilot study examines the effects of Tai Chi on balance, gait and mobility in people with Parkinson disease (PD). Thirty-three people with PD were randomly assigned to either a Tai Chi group or a control group. The Tai Chi group participated in 20 1-h long training sessions completed within 10-13 weeks; whereas, the control group had two testing sessions between 10 and 13 weeks apart without interposed training. The Tai Chi group improved more than the control group on the Berg Balance Scale, UPDRS, Timed Up and Go, tandem stance test, six-minute walk, and backward walking. Neither group improved in forward walking or the one leg stance test. All Tai Chi participants reported satisfaction with the program and improvements in well-being. Tai Chi appears to be an appropriate, safe and effective form of exercise for some individuals with mild-moderately severe PD.     

Medication improves balance and complex gait performance in Parkinson disease

Gait and balance impairments in people with Parkinson disease (PD) may lead to falls and serious injuries. Therefore, it is critical to improve our understanding of the nature of these impairments, including how they respond to prescribed anti-Parkinson medication. This is particularly important for complex balance and gait tasks that may be associated with falls. We evaluated motor function, functional balance, and gait performance during various gait tasks in 22 people with PD OFF and ON medication (PD OFF, PD ON) and 20 healthy older adults. Although MDS-UPDRS-III score, Berg Balance Scale, Mini-Balance Evaluations Systems test, and Timed-Up-and-Go improved in PD with medication, impairments persisted in all measures on medication, compared to controls. Dual task Timed-Up-and-Go did not improve with medication, and PD ON required more time than controls. Gait velocity and stride length improved similarly with medication in PD across forward, fast, backward, dual task forward, and dual task backward gait tasks. Cadence did not change with medication, nor did it differ between PD ON and controls. Velocity and stride length were reduced in PD ON compared to controls. Velocity reductions in PD ON during fast gait were cadence-mediated, while velocity reductions in backward gait were stride length-mediated. Our results suggest functional balance improves with medication in PD and gait performance improves with medication, regardless of task complexity. Remaining impairments on medication highlight the need to examine additional therapeutic options for individuals with PD to reduce the risk of falls.     

Visual availability,balance performance and movement complexity in dancers

Research regarding the complex fluctuations of postural sway in an upright standing posture has yielded controversial results about the relationship between complexity and the capacity of the system to generate adaptive responses. The aim of this study is to compare the performance and complexity of two groups with different levels of expertise in postural control during a balance task. We examined the balance ability and time varying (dynamic) characteristics in a group of 18 contemporary dancers and 30 non-dancers in different visual conditions. The task involved maintaining balance for 30 s on a stability platform with opened or closed eyes. The results showed that dancers exhibited greater balance ability only in open eyes task than non-dancers. We also observed a lower performance in both groups during the test with closed eyes, but only dancers reduced their complexity in closed eyes task. The main conclusion is that the greater postural control exhibited by dancers depends on the availability of visual information.     

Visual availability,balance performance and movement complexity in dancers

Research regarding the complex fluctuations of postural sway in an upright standing posture has yielded controversial results about the relationship between complexity and the capacity of the system to generate adaptive responses. The aim of this study is to compare the performance and complexity of two groups with different levels of expertise in postural control during a balance task. We examined the balance ability and time varying (dynamic) characteristics in a group of 18 contemporary dancers and 30 non-dancers in different visual conditions. The task involved maintaining balance for 30 s on a stability platform with opened or closed eyes. The results showed that dancers exhibited greater balance ability only in open eyes task than non-dancers. We also observed a lower performance in both groups during the test with closed eyes, but only dancers reduced their complexity in closed eyes task. The main conclusion is that the greater postural control exhibited by dancers depends on the availability of visual information.     

Task-specific measures of balance efficacy, anxiety, and stability and their relationship to clinical balance performance

The main objective of this research was to investigate the effects of postural threat on performance of three clinical balance tests. Thirty-one healthy young adults performed quiet stance, maximal reach, and one-leg stance tasks at two levels of postural threat, which was modified through the use of a hydraulic lift. Increased postural threat significantly affected postural control measures for both simple and dynamic balance tests. Physiological and state anxiety increased as a result of increased postural threat whereas ratings of perceived stability and balance efficacy were reduced as a function of increased postural threat. Efforts to diagnose balance disorders based on balance performance may be confounded by the influence of psychological factors.     

Vibration training improves balance in unstable ankles

Functional ankle instability (FAI) is a common condition following ankle injury characterised by increased risk of injury. Ankle sprains are a common acute form of injury suffered in dancing and loss of balance can affect not only risk of injury risk but also performance aesthetics. Whole body vibration training (WBVT) is a new rehabilitation method that has been linked with improving balance and muscle function. 38 female dancers with self reported unilateral FAI were randomly assigned in 2 groups: WBVT and control. Absolute centre of mass (COM) distribution during single leg stance, SEBT normalised research distances and Peroneus longus mean power frequency (f(med)) where measured pre and post 6-week intervention. There was a significant improvement in COM distribution over the 6 weeks from 1.05 ± 0.57 to 0.33 ± 0.42 cm2 (P<0.05), and 4 of the 8 planes of direction in the SEBT Ant, Antlat, Med and Antmed from 77.5 ± 7.1 to 84.1 ± 5.8% (P<0.05) compared to control groups during the course of the 6 week training intervention. There was no evidence of improvement in peroneus longus (f(med)) over time (P=0.915) in either group. WBVT improved static balance and SEBT scores amongst dancers exhibiting ankle instability but did not affect peroneus longus muscle fatigue.     

Clinical assessment of mobility and balance impairments in pre-symptomatic Huntington's disease

BackgroundQuantitative movement analysis can detect impairments in mobility and balance in persons with pre-symptomatic HD (pre-HD); however, it is not known whether clinical tests can also detect such impairments. Given the ease of administering clinical tests, and the importance of assessing mobility and balance, we examined whether clinical tests can detect motor impairments in individuals with pre-symptomatic HD.MethodsTwo clinical tests (Functional Reach Test [FRT] and Timed Up and Go [TUG]) and the Unified Huntington's Disease Rating Scale (UHDRS) were administered, along with quantitative gait analysis, to 15 individuals with pre-symptomatic HD and 15 controls.ResultsThere was no difference in FRT and TUG scores across groups. Neither test was correlated with years to predicted disease onset or with quantitative gait analysis measures.ConclusionClinical assessments such as FRT and TUG are not sensitive in detecting motor impairments in individuals with pre-symptomatic HD. The subtle nature of impairments provides a rationale for the use of quantitative gait analysis in pre-symptomatic HD.     

The interaction of acute physical fatigue with three traditional functional performance tests and the reactive balance test

ObjectivesTo assess the impact of acute physical fatigue on traditional and neurocognitive functional performance tests in recreational athletes.Designrandomized counterbalanced cross-over study, pre-post designSettinglaboratoryParticipantsTwenty recreational athletes (age = 24 ± 3 years)Main outcome measuresWe evaluated fatigue impairments following a 30 s all-out effort in three traditional and one neurocognitive functional performance test. The traditional functional performance tests encompassed the single leg hop for distance (SLH), countermovement jump (CMJ) and Y-balance test (YBT). The neurocognitive functional performance test encompassed the reactive balance test (RBT). A 30 s modified Wingate was used to induce acute physical fatigue.ResultsAcute physical fatigue was successfully induced as indicated by a significant increase in heart rate, systolic blood pressure, blood lactate levels and rating of perceived exertion (p < 0.001). Acute physical fatigue induced significant decreases in RBT accuracy (p = 0.004) and SLH performance (p < 0.001). YBT, CMJ and RBT visuomotor reaction time remained unaffected by acute physical fatigue.ConclusionsAcute physical fatigue impairs SLH performance and decreases accuracy in the RBT. YBT and CMJ performance remained unaffected by acute physical fatigue. Clinicians should be aware of this divergent neurocognitive functional impairments caused by one all-out effort to allow well-informed selection of functional performance tests.     

Arm training in standing also improves postural control in participants with chronic stroke

PurposeTo prove the concept that postural control will improve without specific balance control training during arm training in standing with individuals with chronic stroke.MethodsNine participants (mean age 64 ± 7) received training involving hand orthotic assisted grasp, reach and release in standing 1 h, 3×’s/week for 6 weeks. Training focused on task completion with no explicit instructions provided for postural alignment, weight shift or balance strategy. Testing consisted of quantified measures using NeuroCom? Balance Master, Berg Balance Scale (BBS) and Activities-specific Balance Confidence Scale (ABC).ResultsPost training participants demonstrate increased (p < .05) composite stability scores for sensory organization testing (mean 71.55 ± 12.7–75.55 ± 11). Velocity and directional control of COP weight shift improved for all 9 subjects with 6/9 achieving 100% target acquisition. Directional control improved (p < .05) for medial/lateral movements for all speeds and composite score. Anterior/posterior rhythmic weight shifting increased significantly in COP velocity control at moderate and fast velocities and composite score. Increases in mean BBS (p < .01) from 41.33 ± 10.1–46.88 ± 8.03 exceeded the clinically important cutoff for the scale. Balance confidence improved with ABC mean scores 70.22 ± 14.5–79.55 ± 12.86 (p < .05). Seven participants demonstrated changes above the minimally important difference for this scale.ConclusionsPostural control improved following task oriented arm training in standing without explicit postural control goals, instruction or feedback challenging current training paradigms of isolated postural control training with conscious attention directed to center of pressure location and movement.     

Fluid balance and endurance exercise performance

Dehydration alters cardiovascular, thermoregulatory, central nervous system, and metabolic functions. One or more of these alterations will degrade endurance exercise performance when dehydration exceeds 2% of body weight. These performance decrements are accentuated by heat stress. To minimize the adverse consequences of body water deficits on endurance exercise performance, it is recommended that fluid intake be sufficient to minimize dehydration to less than 2% of body weight loss. This can usually be achieved with fluid intakes of under 1 L x h^-1.     

Ocular dominance and balance performance in healthy adults

PurposeTo evaluate the effect of ocular dominance on balance performance in healthy adult subjects.MethodsOcular dominance was determined in 24 healthy subjects using the hole-in-the-paper test. Balance function was evaluated by computerized dynamic platform posturography (CDPP). Sway index (SI), antero-posterior sway (APS) and lateral sway (LS) were served as outcome parameters.ResultsThe outcome parameters did not differ significantly between dominant and non-dominant eye fixation both in static and angular balance tests (SI—5.47 ± 0.42, 6.23 ± 0.52, p = 0.146 and 18.4 ± 1.07, 19.11 ± 1.15, p = 0.142, respectively; APS—?2.26 ± 4.68, ?5.1 ± 4.6, p = 0.082 and ?1.94 ± 3.33, ?3.64 ± 2.6, p = 0.48, respectively; LS—?1.21 ± 1.46, ?1.12 ± 1.66 p = 0.94 and ?1.98 ± 1.16, ?1.55 ± 1.39, p = 0.69, respectively).ConclusionsOcular dominance does not seem to affect postural function in the monovision and far viewing condition.     

Trunk sway measures of postural stability during clinical balance tests: effects of a unilateral vestibular deficit

This research evaluated whether quantified measures of trunk sway during clinical balance tasks are sensitive enough to identify a balance disorder and possibly specific enough to distinguish between different types of balance disorder. We used a light-weight, easy to attach, body-worn apparatus to measure trunk angular velocities in the roll and pitch planes during a number of stance and gait tasks similar to those of the Tinetti and CTSIB protocols. The tasks included standing on one or two legs both eyes-open and closed on a foam or firm support-surface, walking eight tandem steps, walking five steps while horizontally rotating or pitching the head, walking over low barriers, and up and down stairs. Tasks were sought, which when quantified might provide optimal screening for a balance pathology by comparing the test results of 15 patients with a well defined acute balance deficit (sudden unilateral vestibular loss (UVL)) with those of 26 patients with less severe chronic balance problems caused by a cerebellar-pontine-angle-tumour (CPAT) prior to surgery, and with those of 88 age- and sex-matched healthy subjects. The UVL patients demonstrated significantly greater than normal trunk sway for all two-legged stance tasks especially those performed with eyes closed on a foam support surface. Sway was also greater for walking while rotating or pitching the head, and for walking eight tandem steps on a foam support surface. Interestingly, the patients could perform gait tasks such as walking over barriers almost normally, however took longer. CPAT patients had trunk sway values intermediate between those of UVL patients and normals. A combination of trunk sway amplitude measurements (roll angle and pitch velocity) from the stance tasks of standing on two legs eyes closed on a foam support, standing eyes open on a normal support surface, as well as from the gait tasks of walking five steps while rotating, or pitching the head, and walking eight tandem steps on foam permitted a 97% correct recognition of a normal subject and a 93% correct recognition of an acute vestibular loss patient. Just over 50% of CPAT patients could be classified into a group with intermediate balance deficits, the rest were classified as normal. Our results indicate that measuring trunk sway in the form of roll angle and pitch angular velocity during five simple clinical tests of equilibrium, four of which probe both stance and gait control under more difficult sensory conditions, can reliably and quantitatively distinguish patients with a well defined balance deficit from healthy controls. Further, refinement of these trunk sway measuring techniques may be required if functions such as preliminary diagnosis rather than screening are to be attempted.     

The SWING test: A more reliable test than passive clinical tests for assessing sagittal plane hip mobility

BackgroundClinical assessment of sagittal plane hip mobility is usually performed using the Modified Thomas Test (for extension) and the Straight-Leg-Raise (for flexion) with a goniometer. These tests have limited reliability, however. An active swinging leg movement test (the SWING test), assessed using 3D motion analysis, could provide an alternative to these passive clinical tests.Research questionIs the SWING test a more reliable alternative to evaluate hip mobility, in comparison to the clinical extension and flexion tests?MethodsTen asymptomatic adult participants were evaluated by two investigators over three sessions. Participants performed 10 maximal hip extensions and flexions, with both legs straight and no trunk movement (the SWING test). Hip kinematics was assessed using a 3D motion analysis system. Maximal and minimal hip angles were calculated for each swing and represented maximal hip flexion (SWING flexion) and extension (SWING extension), respectively. The Modified Thomas Test and Straight-Leg-Raise were repeated 3 times for each leg. On the first day, both investigators performed all the tests (SWING + Modified Thomas Test + Straight-Leg-Raise). A week later, a single investigator repeated all the tests. Inter-rater, intra-rater, within-day and between-day reliability were evaluated using intra-class correlation.ResultsIntra-class correlation coefficients for all the tests were superior to 0.8, except for the Modified Thomas Test’s intra-rater, between-day (intra-class correlation 0.673) and the Straight-Leg-Raise’s inter-rater, within-day (intra-class correlation 0.294). The SWING test always showed a higher intra-class correlation coefficient than the passive clinical tests. The only significant correlation found was for the Straight-Leg-Raise and SWING flexion (r = 0.48; P < 0.001).SignificanceThe SWING test seems to be an alternative to existing passive clinical tests, offering better reliability for assessing sagittal plane hip mobility.     

Behavioral outcomes following below-knee amputation in the coordination between balance and leg movement

Lateral leg movement is accompanied by opposite movements of the supporting leg and trunk segments. This kinematic synergy shifts the center of mass (CM) towards the supporting foot and stabilizes its final position, while the leg movement is being performed. The aim of the present study was to provide insight in the behavioral substitution process responsible for the performance of this kinematic synergy. The kinematic synergy was assessed by the principal component analysis (PCA) applied to both hip joints and supporting ankle joint. Patients after unilateral below-knee amputation and control subjects were asked to perform a lateral leg raising. The first principal component (PC(1)) accounted for more than 99% of the total angular variance for all subjects (amputees and controls). PC(1) thus well represents the possibility to describe this complex multi-joint movement as a one degree of freedom movement with fixed ratios between joint angular time course. In control subjects, the time covariation between joints changes holds during all phases of the leg movement (postural phase, ascending and braking phases). In amputees, PC(1) score decreased during the ascending phase of the movement (i.e. when the body weight transfer is completed, while the movement is initiated). We conclude that a feedback mechanism is involved and discuss the hypothesis that this inter-joint coordination in amputees results from a failure in the pre-setting of the inter-joint coupling.     

Sodium bicarbonate improves sprint performance in endurance cycling

ObjectivesOral sodium bicarbonate intake (NaHCO₃) may improve performance in short maximal exercise by inducing metabolic alkalosis. However, it remains unknown whether NaHCO₃ also enhances all-out performance at the end of an endurance competition. Therefore, the present study investigated the effect of stacked NaHCO₃ loading on sprint performance following a 3-h simulated cycling race.DesignDouble-blind randomized placebo-controlled cross-over study.MethodsEleven trained male cyclists (22.3 (18.3–25.3) year; 73.0 (61.5–88) kg; VO₂max: 63.7 (57–72) ml kg^?1 min^?1) ingested either 300 mg kg^?1 body weight NaHCO₃ (BIC) or NaCl (PL). NaHCO₃ or NaCl was supplemented prior to (150 mg kg^?1) and during (150 mg kg^?1) a 3-h simulated cycling race with a 90-s all-out sprint (90S) at the end. Capillary blood samples were collected for determination of blood pH, lactate and HCO₃^? concentrations. Analysis of variance (lactate, pH, HCO₃^?) and paired t-test (power) were applied to compare variables across condition (and time).ResultsNaHCO₃ intake improved mean power during 90S by ～3% (541 ± 59 W vs. 524 ± 57 W in PL, p = 0.047, Cohen’s D = 0.28, medium). Peak blood lactate concentration and heart rate at the end of 90S were higher (p < 0.05) in BIC (16.2 ± 4.1 mmol l ¹, 184 ± 7 bpm) than in PL (12.4 ± 4.2 mmol l^?1, 181 ± 5 bpm). NaHCO₃ ingestion increased blood [HCO₃^?] (31.5 ± 1.3 vs. 24.4 ± 1.5 mmol l^?1 in PL, p < 0.001) and blood pH (7.50 ± 0.01 vs. 7.41 ± 0.03 in PL, p < 0.05) prior to 90S.ConclusionsNaHCO₃ supplementation prior and during endurance exercise improves short all-out exercise performance at the end of the event. Therefore, sodium bicarbonate intake can be applied as a strategy to increase success rate in endurance competitions.     

Creatine supplementation improves sprint performance in male sprinters

The object of this study was to evaluate the effect of creatine (Cr) supplementation in well trained male sprinters. The study was performed as a single blind test on 18 sprinters at a local competition level. During the last two years a substantial part of their training had consisted of a series of maximal sprints with short rest periods to improve their fatigue resistance. The participants consumed either 20 g Cr+20 g glucose per day (Cr group, n=9) or 40 g glucose per day (placebo group, n=9), divided into 4 equal dosages. The effect of Cr on sprint performance was evaluated in two tests, 1 x 100 m sprint and an intermittent 6x60 m sprint. Cr supplementation increased the 100 m sprint velocity (11.68+/-0.27 s vs 11.59+/-0.31 s) and reduced the total time of 6 intermittent 60 m sprints (45.63+/-1.11 s vs 45.12+/-1.1 s), whereas no changes were observed in the placebo group. The sprint velocity was significantly increased in 5 out of 6 intermittent 60 m sprints. Venous blood was drawn 5 min after finishing the final intermittent 60 m run. Plasma lactate, Cr and serum creatinine (Crn) were all increased in the Cr group compared to presupplementation values; no changes were observed in the placebo group. The improved sprint performance suggests an increased availability of energy substrate for performing work, possibly as a result of increased skeletal muscle creatine phosphate (PCr).     

Reliability of power in physical performance tests

The reliability of power in tests of physical performance affects the precision of assessment of athletes, patients, clients and study participants. In this meta-analytic review we identify the most reliable measures of power and the factors affecting reliability. Our measures of reliability were the typical (standard) error of measurement expressed as a coefficient of variation (CV) and the percent change in the mean between trials. We meta-analysed these measures for power or work from 101 studies of healthy adults. Measures and tests with the smallest CV in exercise of a given duration include field tests of sprint running (approximately 0.9%), peak power in an incremental test on a treadmill or cycle ergometer (approximately 0.9%), equivalent mean power in a constant-power test lasting 1 minute to 3 hours on a treadmill or cycle ergometer (0.9 to 2.0%), lactate-threshold power (approximately 1.5%), and jump height or distance (approximately 2.0%). The CV for mean power on isokinetic ergometers was relatively large (> 4%). CV were larger for nonathletes versus athletes (1.3 x), female versus male nonathletes (1.4 x), shorter (approximately 1-second) and longer (approximately 1-hour) versus 1-minute tests (< or = 1.6 x), and respiratory- versus ergometer-based measures of power (1.4 to 1.6 x). There was no clear-cut effect of time between trials. The importance of a practice trial was evident in studies with > 2 trials: the CV between the first 2 trials was 1.3 times the CV between subsequent trials; performance also improved by 1.2% between the first 2 trials but by only 0.2% between subsequent trials. These findings should help exercise practitioners and researchers select or design good measures and protocols for tests of physical performance.