Cerebral palsy (CP) is a permanent disorder affecting the development of movement and posture that causes activity limitations and is attributed to non-progressive disturbances to the developing fetal or infant brain [1
]. Fatigue is another reality in the lives of children with CP [2
] including those who experience spasticity (especially in lower leg muscles during walking) [3
], which is the most common clinical expression of CP [4
]. Rehabilitation therapies are therefore needed to counteract the aforementioned functional limitations.
Slacklining consists of walking or maintaining balance on a polyester band placed between two anchor points. The activity itself is a specialized open motor skill, with demands on muscle coordination and postural stabilization with respect to variable external conditions and their anticipation [5
]. It allows high movement variability, provides a small, non-fixed base of support, elicits fast medio-lateral perturbations to the body and induces high challenges for the postural control [6
]. Previous studies on slacklining have shown that this training modality improves postural stability in young healthy adults and athletes [7
]. Other studies reported that balance tasks performed on a slackline require minimal energy expenditure [10
] and result in low levels of perceived fatigue in athletes or patients with Parkinson’s disease [7
]. Given these benefits, slackline training might improve balance and consequently motor performance in patients with spastic CP. To the best of our knowledge, however, no study has analyzed the effects of a slackline intervention program in this patient population.
The main aim of this study was to analyze the effects of a slackline intervention program on the postural and motor skills of children with spastic CP. It was hypothesized that slacklining would yield significant benefits including an improvement in patients’ postural control.
The flow diagram of study participants is shown in Figure 1
. Twenty-seven patients with spastic CP participated in the study: 14 and 13 assigned to the intervention and control group, respectively. No significant between-group differences were found at baseline (Table 2
) and no adverse events were reported during the intervention.
The intervention group reported a mean RPE value of 7.6 ± 0.6 during the slackline program (corresponding to a perception of “very, very light”). Two significant group by time interactions were found for Xspeed and Abalakov test (p
= 0.006 and p
= 0.015, respectively, Table 3
) with the slackline intervention, and not the control, inducing significant benefits from baseline. Additionally, another non-significant group by time interaction trend was detected for Yspeed (p
= 0.077, Table 3
) for the intervention group, and not for the control. The slackline intervention, and not the control, also yielded significant between-group benefits for Speed (p
= 0.041, r = 0.64, Table 3
= 0.057 in the post-test) and Xspeed (p
< 0.000, r = 0.71, Table 3
= 0.006 in the post-test) and non-significant between-group benefits for Yspeed (p
= 0.062, Table 3
). At the same time, the slackline intervention, and not the control one, yielded significant within-group benefits for Xspeed (p
= 0.055, r = 0.71, Table 3
= 0.015 in the intervention group) and Abalakov test (p
= 0.055, f = 1.99, Table 3
= 0.034 in the intervention group). No between-group effects, within-group effects or group by time interactions were observed for any other outcome.
The present study analyzed the effects of a 6-week slackline intervention program on the postural and motor skills of children with spastic CP. Results show that patients who participated in the slackline program increased their static postural control and motor skills, as reflected by an increased jump in performance. Overall, these findings highlight the potential of slackline training as a simple and inexpensive intervention tool in this patient population. In addition, the program was overall perceived as “very light”, which reinforces its applicability.
The overall improvement in the Speed CoP parameters (with moderate effect sizes) supports the benefits of the slackline intervention on patients’ enhanced postural control, since their reduction represents increases in the ability to maintain an upright stance [21
]. Thus, the present findings suggest that the slackline therapy might be effective for enhancing static postural control, which is in line with previous studies performed in non-clinical populations [5
]. To the best of the authors knowledge, the present study is the first to use this type of intervention in patients with CP, but other training/rehabilitation methods have previously proven effective for the improvement of postural control in patients with CP [23
]. According to Paillard [29
], adaptations in neurophysiological components (neural circuits and sensory processing), cognitive function relative to body representation in space (cortical regulation), and motor function (muscular command) can explain changes in postural control. Thus, it is hypothesized that these variables (e.g., amelioration of the functional deficits of afferent, particularly somatic fibers) might be involved in the benefits observed in the present study [30
No changes were, however, observed in the SEMG activity of the three major postural leg muscles during the posturography test. This finding is in agreement with other studies that have analyzed the effects of slackline training effects on the SEMG of several trunk and lower limb muscles in different populations [5
]. Thus, the existing evidence overall suggests that slackline tasks might not provide a sufficiently high stimulus to elicit changes in SEMG. By contrast, other intervention programs involving balance training have previously yielded positive results in both balance and SEMG in patients with CP [33
The large improvement observed for jump performance (Abalakov test) is also worth noting, as it suggests that slackline training might potentially improve the motor skills of patients with spastic CP. In this regard, however, the scientific literature is equivocal, with all research having been conducted on healthy individuals [4
]. The differences between studies might be due to the different populations included (healthy children, healthy active adults, and athletes), the different interventions applied (total duration ranging from 4 to 6 weeks, 2 to 5 sessions per week, and 5 to 60 min per session) and to the different jump tests used as assessment tools (CMJ, Abalakov, etc.) The mechanisms underlying the benefits on jump performance remain to be elucidated. Nevertheless, given that slackline exercises require a high level of coordination of segment movements, which is essential for jump performance [36
], it seems plausible to hypothesize that slackline training might improve patients’ general coordination skills.
In agreement with previous studies conducted on healthy individuals [4
], the intervention was perceived as “very light”. This underscores that the slackline tasks do not yield a fatigue perception, which is of major clinical relevance because patients with CP commonly express high levels of fatigue, especially those who experience spasticity [37
]. Thus, the current study’s results suggest that slackline training might be a simple, inexpensive and effective tool to enhance postural control and motor skills in children with spastic CP without inducing fatigue, which holds great potential for development. It can be applied through many different rehabilitation protocols (e.g., short-term protocols with few tasks such as simple static body postures and forward and backward steps using only one line or several, long-term protocols with many tasks such as simple and complex static body postures, forward and backward steps, 90º–180º turns, capturing and throwing objects in static body postures, using only one line or several, etc.), being combined with other rehabilitation balance tools (e.g., all types of stable and unstable surface, etc.) and with other rehabilitation topics (e.g., strength, endurance, etc.). Moreover, under the supervision of professionals, it could also be used in recreation and school settings following the aforementioned protocols, since Slackline is a challenging activity for children, who like to be “on the line”, giving their best and trying to challenge their bodies against gravity.
The present study has some limitations that warrant attention. Notwithstanding that the sample size was not small, it should include more patients. The postural control analysis was assessed through CoP parameters, but a center of mass or a full body assessment [37
] might have provided deeper insights. That being said, the patients presented spasticity and muscular atrophy, and thus they might have not been able to exert maximum effort (and consequently maximum SEMG) during the maximum voluntary isometric contraction tests conducted for the SEMG assessment.
Nonetheless, these preliminary findings provide promising data for further investigation. Future studies should present longitudinal designs including detraining and also compare the effectiveness of slackline training with that of other balance training interventions.