Supervised slackline training improves postural stability

Investigating cognitive-motor effects during slacklining using mobile EEG

Balancing is a very important skill, supporting many daily life activities. Cognitive-motor interference (CMI) dual-tasking paradigms have been established to identify the cognitive load of complex natural motor tasks, such as running and cycling. Here we used wireless, smartphone-recorded electroencephalography (EEG) and motion sensors while participants were either standing on firm ground or on a slackline, either performing an auditory oddball task (dual-task condition) or no task simultaneously (single-task condition). We expected a reduced amplitude and increased latency of the P3 event-related potential (ERP) component to target sounds for the complex balancing compared to the standing on ground condition, and a further decrease in the dual-task compared to the single-task balancing condition. Further, we expected greater postural sway during slacklining while performing the concurrent auditory attention task. Twenty young, experienced slackliners performed an auditory oddball task, silently counting rare target tones presented in a series of frequently occurring standard tones. Results revealed similar P3 topographies and morphologies during both movement conditions. Contrary to our predictions we observed neither significantly reduced P3 amplitudes, nor significantly increased latencies during slacklining. Unexpectedly, we found greater postural sway during slacklining with no additional task compared to dual-tasking. Further, we found a significant correlation between the participant's skill level and P3 latency, but not between skill level and P3 amplitude or postural sway. This pattern of results indicates an interference effect for less skilled individuals, whereas individuals with a high skill level may have shown a facilitation effect. Our study adds to the growing field of research demonstrating that ERPs obtained in uncontrolled, daily-life situations can provide meaningful results. We argue that the individual CMI effects on the P3 ERP reflects how demanding the balancing task is for untrained individuals, which draws on limited resources that are otherwise available for auditory attention processing. In future work, the analysis of concurrently recorded motion-sensor signals will help to identify the cognitive demands of motor tasks executed in natural, uncontrolled environments.

Effects of a Short-Term Slackline Training Program on Energy Expenditure and Balance in Healthy Young Adults: A Preliminary Report of a Randomized Controlled Trial

The development of technology and a fast-paced lifestyle has caused a significant decrease in physical activity, especially among young people. These worrying trends can be countered by the use of attractive forms of physical recreation, including the increasingly popular slackline. The aim of this study was to evaluate energy expenditure during slackline training and to analyze changes in dynamic and static balance parameters after supervised slackline training sessions. The study enrolled 28 healthy volunteers (14 men and 14 women aged 21−25) who were randomly divided into two groups: experimental and passive control. The energy expenditure level was the primary outcome and was assessed using the SenseWear Armband. Each participant underwent an initial and final balance assessment using two selected protocols on the Balance Master platform. The intervention lasted 5 days, with 15 min of supervised training per day. The average energy expenditure expressed in MET was 6.0 (±0.7) MET per training session. An analysis of the results regarding static and dynamic balance showed that the group participating in slackline training significantly improved stability on foam surfaces with their eyes open (p < 0.003), as well as tandem walk speeds (p < 0.05), both with small effect sizes. The results suggested that slackline training has the potential to produce significant positive effects on general health statuses following the World Health Organization’s (WHO) recommendations on physical activity. The significant improvement in task-specific balance suggests that slackline training could become an important element of the prevention and rehabilitation of many injuries.

Influence of Controlled Stomatognathic Motor Activity on Sway, Control and Stability of the Center of Mass During Dynamic Steady-State Balance—An Uncontrolled Manifold Analysis

Multiple sensory signals from visual, somatosensory and vestibular systems are used for human postural control. To maintain postural stability, the central nervous system keeps the center of mass (CoM) within the base of support. The influence of the stomatognathic motor system on postural control has been established under static conditions, but it has not yet been investigated during dynamic steady-state balance. The purpose of the study was to investigate the effects of controlled stomatognathic motor activity on the control and stability of the CoM during dynamic steady-state balance. A total of 48 physically active and healthy adults were assigned to three groups with different stomatognathic motor conditions: jaw clenching, tongue pressing and habitual stomatognathic behavior. Dynamic steady-state balance was assessed using an oscillating platform and the kinematic data were collected with a 3D motion capturing system. The path length (PL) of the 3D CoM trajectory was used for quantifying CoM sway. Temporal dynamics of the CoM movement was assessed with a detrended fluctuation analysis (DFA). An uncontrolled manifold (UCM) analysis was applied to assess the stability and control of the CoM with a subject-specific anthropometric 3D model. The statistical analysis revealed that the groups did not differ significantly in PL, DFA scaling exponents or UCM parameters. The results indicated that deliberate jaw clenching or tongue pressing did not seem to affect the sway, control or stability of the CoM on an oscillating platform significantly. Because of the task-specificity of balance, further research investigating the effects of stomatognathic motor activities on dynamic steady-state balance with different movement tasks are needed. Additionally, further analysis by use of muscle synergies or co-contractions may reveal effects on the level of muscles, which were not visible on the level of kinematics. This study can contribute to the understanding of postural control mechanisms, particularly in relation to stomatognathic motor activities and under dynamic conditions.

Slacklining: A narrative review on the origins, neuromechanical models and therapeutic use

Slacklining, the neuromechanical action of balance retention on a tightened band, is achieved through self-learned strategies combining dynamic stability with optimal energy expenditure. Published slacklining literature is recent and limited, including for neuromechanical control strategy models. This paper explores slacklining's definitions and origins to provide background that facilitates understanding its evolution and progressive incorporation into both prehabilitation and rehabilitation. Existing explanatory slacklining models are considered, their application to balance and stability, and knowledge-gaps highlighted. Current slacklining models predominantly derive from human quiet-standing and frontal plane movement on stable surfaces. These provide a multi-tiered context of the unique and complex neuro-motoric requirements for slacklining's multiple applications, but are not sufficiently comprehensive. This consequently leaves an incomplete understanding of how slacklining is achieved, in relation to multi-directional instability and complex multi-dimensional human movement and behavior. This paper highlights the knowledge-gaps and sets a foundation for the required explanatory control mechanisms that evolve and expand a more detailed model of multi-dimensional slacklining and human functional movement. Such a model facilitates a more complete understanding of existing performance and rehabilitation applications that opens the potential for future applications into broader areas of movement in diverse fields including prostheses, automation and machine-learning related to movement phenotypes.

Slacklining as therapy to address non-specific low back pain in the presence of multifidus arthrogenic muscle inhibition

Low back pain (LBP) represents the most prevalent, problematic and painful of musculoskeletal conditions that affects both the individual and society with health and economic concerns. LBP is a heterogeneous condition with multiple diagnoses and causes. In the absence of consensus definitions, partly because of terminology inconsistency, it is further referred to as non-specific LBP (NSLBP). In NSLBP patients, the lumbar multifidus (MF), a key stabilizing muscle, has a depleted role due to recognized myocellular lipid infiltration and wasting, with the potential primary cause hypothesized as arthrogenic muscle inhibition (AMI). This link between AMI and NSLBP continues to gain increasing recognition. To date there is no 'gold standard' or consensus treatment to alleviate symptoms and disability due to NSLBP, though the advocated interventions are numerous, with marked variations in costs and levels of supportive evidence. However, there is consensus that NSLBP management be cost-effective, self-administered, educational, exercise-based, and use multi-modal and multi-disciplinary approaches. An adjuvant therapy fulfilling these consensus criteria is 'slacklining', within an overall rehabilitation program. Slacklining, the neuromechanical action of balance retention on a tightened band, induces strategic indirect-involuntary therapeutic muscle activation exercise incorporating spinal motor control. Though several models have been proposed, understanding slacklining's neuro-motor mechanism of action remains incomplete. Slacklining has demonstrated clinical effects to overcome AMI in peripheral joints, particularly the knee, and is reported in clinical case-studies as showing promising results in reducing NSLBP related to MF deficiency induced through AMI (MF-AMI). Therefore, this paper aims to: rationalize why and how adjuvant, slacklining therapeutic exercise may positively affect patients with NSLBP, due to MF-AMI induced depletion of spinal stabilization; considers current understandings and interventions for NSLBP, including the contributing role of MF-AMI; and details the reasons why slacklining could be considered as a potential adjuvant intervention for NSLBP through its indirect-involuntary action. This action is hypothesized to occur through an over-ride or inhibition of central down-regulatory induced muscle insufficiency, present due to AMI. This subsequently allows neuroplasticity, normal neuro-motor sequencing and muscle re-activation, which facilitates innate advantageous spinal stabilization. This in-turn addresses and reduces NSLBP, its concurrent symptoms and functional disability. This process is hypothesized to occur through four neuro-physiological processing pathways: finite neural delay; movement-control phenotypes; inhibition of action and the innate primordial imperative; and accentuated corticospinal drive. Further research is recommended to investigate these hypotheses and the effect of slacklining as an adjuvant therapy in cohort and control studies of NSLBP populations.

ASSESSING THE POTENTIAL INFLUENCE OF DIFFERENT WALKING STRATEGIES ON PLANTAR PRESSURE DISTRIBUTION TRIGGERED BY A PORTABLE BIOFEEDBACK-BASED GAIT TRAINING DEVICE

Plantar pressure refers to the interfacial contact pressure between the foot and the supporting surface during daily locomotor activities. Information derived from plantar pressure measures is essential in gait and posture research for diagnosing patho-mechanics associated with the musculoskeletal diseases. In particular, it is compulsory to reduce the abnormally high plantar pressure in people with diabetes for the prevention and treatment of foot ulcerations in this population. In this study, a portable biofeedback-based gait training device is developed to advocate able-bodied subjects to adopt different movement patterns in walking to manipulate the plantar pressure distribution under the foot. Through the simultaneous detection of the plantar pressure pattern and the kinematics of the lower extremity joints, it was revealed that the unloading effects for the plantar site in particular to the lateral forefoot subareas were more abundant through biofeedback-assisted gait alterations than the self-awareness control for gait adjustment. In addition, the corresponding relationship between joint coordination and pressure redistribution pattern was obtained, which could potentially be used in gait retraining interventions to correct abnormal plantar pressure patterns in people with diabetes.

Effects of Slackline Training on Acceleration, Agility, Jump Performance and Postural Control in Youth Soccer Players

The goal of this study was to assess the effects of a supervised slackline training program in a group of soccer players. Thirty-four male division I under-19 players (16.64 ± 0.81 years) agreed to participate in the study. They were randomly divided into an experimental group (EG) and a control group (CG). The first group (EG) followed a 6-week supervised slackline training program (3 sessions/week; 5-9 min/session), while the CG performed only regular soccer training. Several variables were assessed in all participants: acceleration (20-m sprint test), agility (90º turns test), jump performance (squat jump, countermovement jump), and postural control (Center of Pressure ( CoP) testing: length, area, speed, Xmean, Ymean, Xspeed, Yspeed, Xdeviation, Ydeviation). Ratings of perceived exertion and local muscle ratings of perceived exertions were also recorded after each slackline training session. At post-tests, there was a significant increase only in the EG in acceleration, agility, squat jump and countermovement jump performance, as well as several CoP variables: area in the bipedal support on a firm surface, and length, area and speed in the left leg on a firm surface. The program was rated as “somewhat hard” by the players, while quadriceps, gastrocnemius and tibialis anterior were the most exerted muscles while slacklining. In conclusion, slackline training can be an effective training tool for young, high-level soccer players.

Short-term slackline training improves task-specific but not general balance in female handball players

Slackline training has been shown to improve balance and neuromuscular performance. However, recent studies suggested that balance is task-specific, implying that transferability of balance skills is limited and might depend on the similarity of the tasks. This study therefore investigated if short-term slackline training could improve performance in balance tasks that are either more or less similar to the trained slackline task. Furthermore, we assessed potential transfer effects to other neuromuscular performance tests. 25 female handball players (23.7 ± 3.9 years) participated in our study and were matched to either a slackline training (SLT; n = 14) or a control group (CON; n = 11). The intervention comprised 12 sessions with overall 120 minutes of slackline training using single and double slacklines. Slackline standing time and measures of dynamic and static balance were assessed before and after the intervention, as well as power and sprint-related performance parameters. Two-way repeated-measures ANOVA found a significant group × time interaction for slackline standing time, indicating larger training effects for SLT. For the remaining dynamic and static balance tests, no significant interactions were found. With regard to neuromuscular performance, there was a significant group × time interaction only in change of direction. In essence, the study showed that slackline training induced task-specific balance improvements without affecting general balance. This adds further evidence to the task-specificity principle of balance, although the specificity of the sample as well as the briefness of the intervention should be taken into account when generalizing our findings. Nonetheless, this study contains practical implications for team sports interventions and future balance training studies, highlighting the importance of selecting appropriate balance exercises to yield rapid and the desired training outcomes.

Effects of traditional balance and slackline training on physical performance and perceived enjoyment in young soccer players

The aim of this study was to evaluate the effects of 12-week balance and slackline training programs on physical performance and perceived enjoyment scale in young soccer players. Forty-one preadolescent soccer players were assigned to two experimental groups performing traditional balance (BLT) or slackline training (SLT), and a control group. Pre-post assessment encompassed Balance Error Scoring System (BESS), Star Excursion Balance test (SEBT), sprint with 90° turns (S90), and countermovement jump (CMJ). The rate of perceived enjoyment scale (PACES) was applied at the end of the experimental period. SLT and BLT improved similarly in BESS, SEBT and S90. No changes were detected in the CMJ. Regarding PACES score, SLT presented significantly higher values than BLT. Young athletes may benefit from a motivating training approach, thus, a designed program based on slackline drills should be preferable to improve physical performance in terms of balance and change of direction ability in preadolescent soccer players.

Slackline Training (Balancing Over Narrow Nylon Ribbons) and Balance Performance: A Meta-Analytical Review

BACKGROUND

Adequate static and dynamic balance performance is an important prerequisite during daily and sporting life. Various traditional and innovative balance training concepts have been suggested to improve postural control or neuromuscular fall risk profiles over recent years. Whether slackline training (balancing over narrow nylon ribbons) serves as an appropriate training strategy to improve static and dynamic balance performance is as yet unclear.

OBJECTIVE

The aim was to examine the occurrence and magnitude of effects of slackline training compared with an inactive control condition on static and dynamic balance performance parameters in children, adults and seniors.

DATA SOURCES

Five biomedical and psychological databases (CINAHL, EMBASE, ISI Web of Knowledge, PubMed, SPORTDiscus) were screened using the following search terms with Boolean conjunctions: (slacklin* OR slack-lin* OR tight rop* OR tightrop* OR Slackline-based OR line-based OR slackrop* OR slack-rop* OR floppy wir* OR rop* balanc* OR ropedanc* OR rope-danc*) STUDY SELECTION: Randomized and non-randomized controlled trials that applied slackline training as an exercise intervention compared with an inactive control condition focusing on static and dynamic balance performance (perturbed and non-perturbed single leg stance) in healthy children, adults and seniors were screened for eligibility.

DATA EXTRACTION

Eligibility and study quality [Physiotherapy Evidence Database (PEDro) scale] were independently assessed by two researchers. Standardized mean differences (SMDs) calculated as weighted Hedges' g served as main outcomes in order to compare slackline training versus inactive control on slackline standing as well as dynamic and static balance performance parameters. Statistical analyses were conducted using a random-effects, inverse-variance model.

RESULTS

Eight trials (mean PEDro score 6.5 ± 0.9) with 204 healthy participants were included. Of the included subjects, 35 % were children or adolescents, 39 % were adults and 26 % were seniors. Slackline training varied from 4 to 6 weeks with 16 ± 7 training sessions on average, ranging from 8 to 28 sessions. Mean overall slackline training covered 380 ± 128 min. Very large task-specific effects in favor of slackline training compared with the inactive control condition were found for slackline standing time {SMD 4.63 [95 % confidence interval (CI) 3.67-5.59], p < 0.001}. Small and moderate pooled transfer effects were observed for dynamic [SMD 0.52 (95 % CI 0.08-0.96), p = 0.02] and static [SMD 0.30 (95 % CI -0.03 to 0.64), p = 0.07] standing balance performance, respectively.

CONCLUSIONS

Slackline training mainly revealed meaningful task-specific training effects in balance performance tasks that are closely related to the training content, such as slackline standing time and dynamic standing balance. Transfer effects to static and dynamic standing balance performance tasks are limited. As a consequence, slackline devices should be embedded into a challenging and multimodal balance training program and not used as the sole form of training.

Changes in balance coordination and transfer to an unlearned balance task after slackline training: a self-organizing map analysis

How humans maintain balance and change postural control due to age, injury, immobility or training is one of the basic questions in motor control. One of the problems in understanding postural control is the large set of degrees of freedom in the human motor system. Therefore, a self-organizing map (SOM), a type of artificial neural network, was used in the present study to extract and visualize information about high-dimensional balance strategies before and after a 6-week slackline training intervention. Thirteen subjects performed a flamingo and slackline balance task before and after the training while full body kinematics were measured. Range of motion, velocity and frequency of the center of mass and joint angles from the pelvis, trunk and lower leg (45 variables) were calculated and subsequently analyzed with an SOM. Subjects increased their standing time significantly on the flamingo (average +2.93 s, Cohen's d = 1.04) and slackline (+9.55 s, d = 3.28) tasks, but the effect size was more than three times larger in the slackline. The SOM analysis, followed by a k-means clustering and marginal homogeneity test, showed that the balance coordination pattern was significantly different between pre- and post-test for the slackline task only (χ ² = 82.247; p < 0.001). The shift in balance coordination on the slackline could be characterized by an increase in range of motion and a decrease in velocity and frequency in nearly all degrees of freedom simultaneously. The observation of low transfer of coordination strategies to the flamingo task adds further evidence for the task-specificity principle of balance training, meaning that slackline training alone will be insufficient to increase postural control in other challenging situations.

Could Slackline Training Complement the FIFA 11+ Programme Regarding Training of Neuromuscular Control?

The current study compared changes in neuromuscular control between slackline training and the stabilization training elements of the FIFA 11+ programme. Twenty-five students in 2 groups performed a 12-unit training programme. The slackline training group (n = 13) exclusively trained with a slackline. The stabilization training group (n = 12) practised exercises as described in the second part of the FIFA 11+ programme. Improvements in balance were assessed using three tests for dynamic, quasi-static, and perturbed postural control: the star excursion balance test (SEBT), the closed-eye single-leg stance, and the MFT S3-Check. Both groups significantly improved the stability and sensorimotor index of the MFT S3-Check (p < .001), their range on the SEBT (p < .001), and the duration of closed-eye single-leg stance (p < .001). The group × training interaction was significant for the MFT S3-Check (stability index: p = .042; sensorimotor index: p = .004) and the SEBT (dominant leg: p = .003; averaged both legs: p = .016), with the slackline training group showing a larger training effect than the stabilization training group. The results of the present study suggest that slackline training offers similar - or better - improvements in neuromuscular control as the FIFA 11+ warm-up programme. If compliance with the FIFA 11+ programme is declining, then slacklining might offer an alternative approach to reach the training goals of improved sensorimotor control.

Improvements in Orientation and Balancing Abilities in Response to One Month of Intensive Slackline-Training. A Randomized Controlled Feasibility Study

Background: Slackline-training has been shown to improve mainly task-specific balancing skills. Non-task specific effects were assessed for tandem stance and preferred one-leg stance on stable and perturbed force platforms with open eyes. It is unclear whether transfer effects exist for other balancing conditions and which component of the balancing ability is affected. Also, it is not known whether slackline-training can improve non-visual-dependent spatial orientation abilities, a function mainly supported by the hippocampus.

Objective: To assess the effect of one-month of slackline-training on different components of balancing ability and its transfer effects on non-visual-dependent spatial orientation abilities.

Materials and Methods: Fifty subjects aged 18–30 were randomly assigned to the training group (T) (n = 25, 23.2 ± 2.5 years; 12 females) and the control group (C) (n = 25, 24.4 ± 2.8 years; 11 females). Professional instructors taught the intervention group to slackline over four consecutive weeks with three 60-min-trainings in each week. Data acquisition was performed (within 2 days) by blinded investigators at the baseline and after the training. Main outcomes Improvement in the score of a 30-item clinical balance test (CBT) developed at our institute (max. score = 90 points) and in the average error distance (in centimeters) in an orientation test (OT), a triangle completion task with walking and wheelchair conditions for 60°, 90°, and 120°.

Results: Training group performed significantly better on the closed-eyes conditions of the CBT (1.6 points, 95% CI: 0.6 to 2.6 points vs. 0.1 points, 95% CI: –1 to 1.1 points; p = 0.011, ηp2 = 0.128) and in the wheelchair (vestibular) condition of the OT (21 cm, 95% CI: 8–34 cm vs. 1 cm, 95% CI: –14–16 cm; p = 0.049, ηp2 = 0.013).

Conclusion: Our results indicate that one month of intensive slackline training is a novel approach for enhancing clinically relevant balancing abilities in conditions with closed eyes as well as for improving the vestibular-dependent spatial orientation capability; both of the benefits are likely caused by positive influence of slackline-training on the vestibular system function.

Slacklining and stroke: A rehabilitation case study considering balance and lower limb weakness

To ascertain the effectiveness of slacklining as a supplementary therapy for elderly stroke patients who are functionally non-progressing. This case study involved an 18-mo prospective observation of the management of an 87-year-old female stroke-patient of the left hemisphere with reduced balance, reduced lower limb muscular activation, hypertonia, and concurrent postural deficits. This entailed the initial acute care phase through to discharge to home and 18-mo final status in her original independent living setting. The introduction of slacklining as an adjunct therapy was made 12 mo post incident. Slacklining involves balance retention on a tightened band where external environmental changes cause a whole-body dynamic response to retain equilibrium. It is a complex neuromechanical task enabling individualized self-developed response strategies to be learned and adapted. This facilitates the innate process of balance retention, lower-limb and core muscle activation, and stable posture through a combination of learned motor skills and neurological system down regulation. Individuals adopt and follow established sequential motor learning stages where the acquired balance skills are achieved in a challenging composite-chain activity. Slacklining could be considered an adjunct therapy for lower limb stroke rehabilitation where function is compromised due to decreased muscle recruitment, decreased postural control and compromised balance. Initial inpatient rehabilitation involved one-month acute-care, one-month rehabilitation, and one-month transitional care prior to home discharge. A further six months of intensive outpatient rehabilitation was provided with five hourly sessions per week including:supervised and self-managed hydrotherapy, plus one individual and two group falls’ prevention sessions. These were supported by daily home exercises. At 12 mo post incident, recovery plateaued, then regressed following three falls. Rehabilitation was subsequently modified with the hydrotherapy retained and the group sessions replaced with an additional individual session supplemented with slacklining. The slacklining followed stages one and two of a standardized five-stage protocol. Self-reported functional progression resumed with improvement by 14 mo which further increased and was sustained 18 mo (Students’t test P < 0.05). Slacklining’s external stimulations activate global-body responses through innate balance, optimal postural and potentially down-regulated reflex control. Incorporated into stroke rehabilitation programs, slacklining can provide measurable functional gains.

Biomechanical Analysis of a Dynamic Stability Test System to Evoke Sway and Step Recovery

This paper reports on the dynamic analysis and experimental validation of a method to perturb the balance of subjects in quiet standing. Electronically released weights pull the subject's waist through a specified displacement sensed by a photoelectric sensor. A dynamic model is derived that computes the force applied to the subject as a function of waist acceleration. This model accurately predicts the acceleration of mock subjects (suspended masses) with high repeatability. The validity and simplicity of this model suggest that this method can provide a standard for provocation testing on stable surfaces. Proof-of-concept trials on human subjects demonstrate that the device can be used with a force platform and motion tracking and that the device can induce both sway and step recoveries in healthy male adults.

Aspects of Dynamic Balance Responses: Inter- and Intra-Day Reliability

The Posturomed device is used as a scientific tool to quantify human dynamic balance ability due to unexpected perturbations, and as a training device. Consequently, the question arises whether such measurements are compromised by learning effects. Therefore, this study aimed to analyze inter- and intra-day reliability of dynamic balance responses using the Posturomed. Thirty healthy young subjects participated (24.3±3.2 years). The Posturomed was equipped with a triggering mechanism to enable unexpected, horizontal platform perturbations. A force platform was used to quantify Center of Pressure (COP) excursions for two time intervals: interval 1 (0–70 ms post perturbation) and interval 2 (71–260 ms post perturbation). Dynamic balance tests were performed in single leg stances in medio-lateral and anterior-posterior perturbation directions. Inter- and intra-day reliability were assessed descriptively using Bland-Altman plots and inferentially using tests for systematic error and intra-class-correlations. With regard to the mean COP excursions for every subject and all intervals, some cases revealed significant differences between measurement sessions, however, none were considered relevant. Furthermore, intra class correlation coefficients reflected high magnitudes, which leads to the assumption of good relative reliability. However, analyzing inter- and intra-day reliability using Bland-Altman plots revealed one exception: intra-day comparisons for the anterior-posterior direction in interval 2, which points towards possible learning effects. In summary, results reflected good overall reliability with the exception of certain intra-day comparisons in the anterior-posterior perturbation direction, which could indicate learning effects in those particular conditions.

Ice skating promotes postural control in children

High fall rates causing injury and enormous financial costs are reported for children. However, only few studies investigated the effects of balance training in children and these studies did not find enhanced balance performance in postural (transfer) tests. Consequently, it was previously speculated that classical balance training might not be stimulating enough for children to adequately perform these exercises. Therefore, the aim of this study is to evaluate the influence of ice skating as an alternative form of balance training. Volunteers of an intervention (n = 17; INT: 13.1 ± 0.4 years) and a control group (n = 13; CON: 13.2 ± 0.3 years) were tested before and after training in static and dynamic postural transfer tests. INT participated in eight sessions of ice skating during education lessons, whereas CON participated in normal physical education. Enhanced balance performance was observed in INT but not in CON when tested on an unstable free-swinging platform (P < 0.05) or when performing a functional reach test (P < 0.001). This is the first study showing significantly enhanced balance performance after ice skating in children. More importantly, participating children improved static and dynamic balance control in postural tasks that were not part of the training.

The influence of 'Slacklining' on quadriceps rehabilitation, activation and intensity

OBJECTIVES

To determine and compare the level of quadriceps activation for knee injured participants during kinetic open-chain, closed-chain and composite-chain (Slackline) clinical exercises. Quadriceps activation is a critical component of lower limb movement and subsequently, rehabilitation. However, selective activation can be difficult due to pain, loss of function and impaired neuro-motor activation.

DESIGN

Repeated measures (within-subjects) ANOVA.

METHODS

Consecutive physiotherapy outpatients (n=49, 41.8±16.8 years, range 13-72 years, 57% female) with an acute (<2 weeks) knee injury were recruited. Participants were assessed for quadriceps activation using skin mounted electromyography during five separate clinical quadriceps activation exercises: two open-chain, inner range quads and straight leg raise; two closed-chain, step down and step up; and a composite-chain, slacklining step-up. Outcome measures were: median score on electromyography as measured in microvolts (μV); and perceived exertion on an 11-point numerical rating scale.

RESULTS

Median scores of the open- and closed-chain exercises showed no statistical difference, while composite-chain Slackline exercise showed significantly (p<0.0001) higher quadriceps activation (F(2.52, 121.00)=21.53, p<0.0001) at significantly lower exertion (F(1.62, 77.70)=26.88, p<0.0001).

CONCLUSIONS

The use of Slackline rehabilitation training can provide significant increases in activation and recruitment of the quadriceps for composite-chain exercises in the clinical setting. This activation occurs spontaneously at significantly lower levels of perceived exertion. This spontaneous quadriceps activation in a selective and simple manner is a valuable adjunct exercise for lower limb rehabilitation programmes. This is of particular relevance for the outpatient setting and circumstances where the quadriceps is inhibited and activation is required.

Effects of 4-week slackline training on lower limb joint motion and muscle activation

OBJECTIVES

To investigate the effects of four weeks of slacklining on lower limb kinematics and muscle activity following a slip of the upright stance.

DESIGN

A randomized, gender matched study.

METHODS

Twenty-four young healthy adults participated in the study and were assigned to either a training or a control group. The training group completed a 4-week training program on slacklines, while the control group received no slackline training. Before and after training, participants performed single leg standing tasks on a moveable platform. During medio-lateral platform perturbation, platform displacement, lower limb joint motion (ankle, knee and hip) and surface electromyography (EMG) measurements from six lower limb muscles were recorded.

RESULTS

In the training group, a decrease in platform mean and maximum velocity (all p<0.05) was detected, but no changes were observed for the release time and maximum deflection (all p>0.05) of the platform. Regarding lower limb kinematics, a reduced corrective action was detected in the knee joint (p<0.05), whereas only a trend towards a decrease could be observed in the ankle joint (p<0.1). EMG data revealed an enhanced activation of the rectus femoris (p<0.05), as well as a trend to increased rectus femoris to biceps femoris co-activation (p=0.06) in the preparatory phase for training group.

CONCLUSIONS

The data strongly support that slacklining can improve postural control and enhance functional knee joint stability, which seems to be induced by enhanced preparatory muscle activation of the rectus femoris.