Effects of motor skills training program on the cardiac autonomic control in children with developmental coordination disorder: a preliminary study

Background

Developmental coordination disorder (DCD) is a condition in which the coordination of movements is poor and interferes in many functional activities, such as riding a bicycle, writing, drawing or throwing and catching objects [1]. DCD is not associated to another physical, sensory or intellectual impairment [2] and its prevalence in school children is approximately 6–8% [1].

Besides poor motor skill performance, children with DCD are less likely to participate in different kinds of physical activities [3,4]. Therefore, sedentary lifestyle is very common in these children, which might affect their health and predispose them to cardiac risk factors in the future [5]. Indeed, some studies have shown that children with DCD present abnormalities regarding cardiac autonomic control, which is a non-invasive marker for risk of a cardiovascular event [6–8].

The management and therapeutic approaches for DCD is usually based on motor skills training programmes, which has been shown to improve motor performance and motor learning [9–11]. However, to our knowledge, no studies have assessed the effects of a motor skills training programme on the cardiac autonomic control in these children.

Therefore, the aim of this preliminary study was to evaluate the effects of a 16-session motor skill training programme on the cardiac autonomic control and motor performance in children with DCD.

Methods

Subjects

Six children (mean, 7.7 years; SD, 0.5 years) were recruited from positive screening for DCD by applying the Movement Assessment Battery for Children – Second Edition (MABC-2) with a cut-off point for the total score ≤16 [12] and the Developmental Coordination Disorder Questionnaire (DCDQ), based on the following scores: for ages 5 to 7 years and 11 months: <46; for ages 8 to 9 years and 11 months: <55; and for ages 10 to 15 years and 6 months: <57 [13].

Motor training

Children were submitted to a 16-session motor skills training programme twice a week. Each training session was individualised and lasted approximately 60 min. The motor skills training programme consisted of six different activities and each activity was performed for 7 min. The therapist was blinded to the children’s outcomes obtained at the baseline. The activities are listed in Table 1.

Table 1. Motor activities performed in the motor skills training programme.

Motor activities	Description
Frisbee	Children were asked to throw a frisbee aiming to achieve the highest score zone of an aim positioned on the ground 4 m away from them
Table tennis	Children were asked to play table tennis on a half folded table tennis table by striking the ball with their racket and hitting the ball onto the folded table. The children had to make eye contact with the ball throughout the whole game
Bowling	Children were asked to roll a ball towards 10 PET bottles filled with water (simulating pins) positioned 4.83 m away. The objective was to score points by knocking down as many pins as possible
Archery	Children were asked to shoot plastic arrows by using a plastic bow at a target positioned 2.30 m away
Balance disc	Children were asked to perform balancing tasks by standing in 14 different static postures on a balance disk. Each position had to be maintained for 15 s
Balance beams	Children were asked to walk on three wooden balance beams of 3 m long each positioned 3 cm above the ground with different thicknesses (3 cm, 4.5 cm and 6 cm). The children had to walk without touching the ground during a total time of 7 min

Measurements

All children underwent the MABC-2 and RR intervals recording (at resting supine position for 10 min) one week before (Baseline) and one week after (Post) the 16-session motor skills training programme. Cardiac autonomic control was assessed by means of heart rate variability (HRV), using time domain (Variance, SDNN and RMSSD indices) and spectral (High Frequency, HF; Low Frequency, LFnu and LF/HF ratio indices) analyses in a region of 256 consecutive beats with the greatest stability in the RR time series for all the participants [14].

Statistical analyses

The paired Student t test was used to compare the baseline vs. post values. The significance level was set at 5%. The effect size was calculated by Cohen’s d coefficient and classified as small effect size (d = 0.30), moderate effect size (d = 0.50) and large effect size (d = 0.80) [15].

Results

Table 2 shows the MABC-2 values and cardiac autonomic control indices before and after the motor training programme. Children with DCD showed a significant increase (p = .03, d = 1.54) in the MABC-2 total score after the training programme.

Table 2. MABC-2 values and cardiac autonomic control indices before and after motor training.

Variables	Pre-test condition Mean (SD)	Post-test condition Mean (SD)	p-value	Effect size
MABC-2 total scores	53.8 (6.9)	68.0 (12.0)	.03	1.54
Variance RR (ms^2)	7182.83 (2099.38)	3415.17 (1310.20)	.02	2.05
SDNN (ms)	82.08 (13.89)	54.57 (10.92)	.02	2.17
RMSSD (ms)	91.2 (44.46)	52.35 (15.63)	.02	0.94
HF (ms^2)	3502.01 (1149.08)	1580.83 (771.85)	.02	1.89

MABC-2: Movement Assessment Battery for Children – Second edition; Variance RR: variance of RR interval time series; SDNN: standard deviation of RR intervals; RMSSD: square root of the mean squared differences of successive RR intervals; HF: high frequency component of RR variability expressed in absolute unit.

Regarding the cardiac autonomic control, children with DCD presented a significant decrease in variance RR (d = 2.05, p = .02) and SDNN indices (d = 2.17, p = .02) after the training programme, reflecting a decrease in the overall HRV. A significant decrease in the RMSSD (d = 0.94, p = .02) and in the HF (p = .02, d = 1.89) indices were also observed, reflecting a decrease in the cardiac parasympathetic modulation.

Conclusions

The results revealed that the 16-session motor skills training programme, proposed in the present study, was effective in increasing motor skills performance and in altering cardiac autonomic modulation, by decreasing overall HRV and cardiac parasympathetic modulation, in children with DCD.

Implications

This study highlights the effectiveness of motor skills training in improving motor skills performance in children with DCD. Furthermore, the intervention decreased overall HRV and cardiac parasympathetic modulation, which was unexpected, since decreased HRV has been associated with increased risk for cardiovascular events [8,16]. On the other hand, decreasing parasympathetic modulation it is of interest in some clinical conditions, such as children with vasovagal syncope [17]. Therefore, this study is a starting point for future studies to address whether children with DCD share a similar autonomic profile with children with vasovagal syncope, which could also contribute to low activity levels commonly seen in DCD children.

Ethics approval

Approved by Ethics Committee on Human Research of the Federal University of São Carlos (CAEE/47091115.0.0000.5504), BR.

Disclosure statement

• No potential conflict of interest was reported by the authors.

Funding

This work was funded by FAPESP – Research Support Foundation of the State of São Paulo (Process number 2015/24291-0).