Time Limited Benefits of Physical and Proprioceptive Training on Physical Fitness Components in Children With Autism Spectrum Disorders

Abstract

In this study, we explored the immediate and three-month follow-up effects of physical training on physical fitness in children with autism spectrum disorder (ASD). We randomly assigned 20 children with ASD (age 8–11 years) into an experimental group (EG; n = 10) and a control group (CG; n = 10). The EG participated in an 8-week training program involving both strength and proprioceptive exercises (three 60-minute sessions/week), while the CG simply maintained their daily activities. We assessed physical fitness components for each participant at baseline, post-training, and at a 3-month follow-up. The physical training intervention significantly improved physical fitness of these children with ASD in terms of their flexibility (p < .001; 32.46%), lower limbs strength (p = .003; 36.98%), lower body power (p < .001; 41.78%) and functional mobility (p < .001; 25.56%). However, these addition training-induced gains were lost at follow-up for lower limbs strength (p < .001), flexibility (p < .001), and functional mobility (p = .034)). Physical training was effective for improving physical fitness in children with ASD, but the loss of these gains at three months follow-up underscored the need for continuous physical exercise.

Keywords

exercise benefits exercise limitations physical activity exercise follow-up ASD and exercise

Introduction

Autism Spectrum Disorder (ASD) is the most common pediatric neurodevelopmental disorder of early childhood, and its symptoms persist through life (American Psychiatric Association, 2013). Children with ASD experience challenges in social communication and interactions, and they exhibit a restricted pattern of behavior and interests (American Psychiatric Association, 2013). Limited levels of physical activity as well as delayed physical fitness, particularly in children and adolescents, may accompany these deficits (Pan, 2014; Tyler et al., 2014). Several investigators have reported that children with ASD showed higher sedentary behavior and lower levels of physical activity than their typically developing peers, often resulting in lower physical fitness (Gehricke et al., 2020; Kaur et al., 2018; Pan, 2014; Tyler et al., 2014).

Physical fitness, the ability to efficiently perform leisure activities and advanced motor skills in sports, is widely recognized as a major component of overall physical well-being across the lifespan (Zou et al., 2017). Limited levels of physical activity and low physical fitness may place individuals with ASD at a high risk of chronic diseases (Healy et al., 2019). There is evidence that physical activity interventions for individuals with ASD have improved their physical conditioning (Movahedi et al., 2013; Zhao & Chen, 2018), cognitive functioning (Hynes & Block, 2022), communication skills (Hameury et al., 2010), social emotional functioning (Bremer et al., 2016), academic engagement (Nicholson et al., 2011), stereotypic behaviors (Bremer et al., 2016), and even their parent’s mental health (Zhao et al., 2021).

Importantly, prior researchers have demonstrated the effects of several different physical training methods (e.g., combined physical training, game-based exercise, and mini-basketball) for improving physical fitness in children with ASD (Cai et al., 2020; Haghighi et al., 2022; Yu et al., 2018). Notably, strength training is an evolving approach with accumulating supportive evidence for both typically developing children (Jaimes et al., 2022) and children with disabilities (Kachouri et al., 2016; Merino-Andrés et al., 2022; Suarez-Villadat et al., 2022). More specifically, strength training has been found to improve some measures of physical fitness among adolescents with ASD (Lochbaum & Crews, 2003). Physical training based on strength exercises has improved metabolic health and reduced autistic traits (Toscano et al., 2018), and some have reported that proprioceptive training is also effective for enhancing neuromotor control and functional performance (Aman et al., 2015; Gidu et al., 2022) and promoting motor coordination in children with ASD (Moeini et al., 2019). In fact, since proprioceptive training targets improvements in proprioceptive function (Aman et al., 2015), it focuses on somatosensory signals such as proprioceptive or tactile afferents (Aman et al., 2015) and the coordinated use of multiple muscles and joints (Oh et al., 2018), making it particularly well suited for those children with ASD who need help achieving independence in their daily activities. Considering the positive effects of strength and proprioceptive training programs on functional and physical performances, physical training that includes these elements holds promise for children with ASD. When comparing children with ASD and a group of age and sex matched neurotypical controls, Armitano-Lago et al. (2021) found that the youth with ASD demonstrated reduced strength and proprioceptive capabilities. These authors concluded that a rehabilitative program aiming to improve lower extremity strength and proprioception abilities would be well suited to these children’s motor functions and long-term health (Armitano-Lago et al., 2021). To the best of our knowledge, no investigators have yet studied the immediate and delayed effects of physical training based on both strength and proprioceptive exercises in children with ASD.

As noted above, a physical training program involving ball games, rhythmic movements, and resistance exercises improved physical fitness (static balance, handgrip strength, upper and lower body power, flexibility and agility) in children with ASD (Haghighi et al., 2022). While these findings confirmed the effectiveness and importance of these combined training modalities for children with ASD, these authors did not explore the sustainability of their training effects on follow-up. In fact, there is too little existing data addressing the persistence of functional fitness changes following the cessation of exercise interventions in children with ASD. In this context, Pan et al. (2017) explored the effect of a motor skill intervention on fundamental motor skills. Their results showed sustained gains of training in strength and agility, manual coordination, and body coordination for at least 12 weeks. In separate research Pan (2011) investigated the effect of aquatic training on physical fitness and aquatic skills in children with ASD and found that muscular strength/endurance benefits from this aquatic program were maintained for 14 weeks, while cardiovascular fitness, and flexibility benefits were lost over that period. Even in typically developing children, the physical fitness benefits of physical training (combined resistance and plyometric) generally disappeared 12 weeks after training ceased (Ingle et al., 2006; Qi et al., 2019).

In the context of this prior research, we explored the immediate and 3-month follow-up effects of strength and proprioceptive training on flexibility, lower limbs strength, power, and functional mobility in children with ASD. We hoped our findings might provide educators with an effective exercise plan to make a lasting difference in the physical fitness of these children. We hypothesized that a novel physical training program (with both proprioceptive and strength exercises) would promote lasting positive changes in these selected physical fitness components in our participants.

Method

Participants

We conducted an a priori power analysis to estimate the minimum sample size necessary for sufficient statistical power in the current study (Beck, 2013) using G*power software for Windows (version 3.1.9.2; Heinrich Heine University Düsseldorf, North nrhine-Westphalia, Germany) as recommended by (Faul et al., 2007). We used an estimated effect size, Cohen’s f (calculated based on a partial ηp²) of 0.48 based on findings by Cai et al. (2020). We set statistical significance at p <.05, power at .80, the correlation among repeated measures at 0.50 and the non-sphericity correction at 1. The power analysis calculation yielded a total estimated required sample size for the two groups to be 12 participants. To accommodate a possible drop-out of some participants, we recruited more participants than this number.

Our participants were 20 Tunisian children (4 girls and 16 boys), aged 8–11 years, who a licensed child psychologist or psychiatrist determined to have ASD, based on diagnostic criteria published in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) (American Psychiatric Association, 2013). All participants were diagnosed with mild ASD without intellectual disability (Full Scale IQ score ˃ 70, as determined by a psychologist who tested the children with the Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV; Wechsler, 2003) and reported the results in their medical files). The participants were recruited through word of mouth from primary schools in which they were integrated with typically developing children.

Participants were excluded if they had one or more comorbid psychiatric disorders; a complex neurological disorder (e.g., epilepsy, phenylketonuria, fragile X syndrome, tuberous sclerosis); visual and/or auditory disturbances; and/or a medical history of head trauma or any medical condition that could limit exercise intervention. None of these children practiced a particular physical activity on a regular basis outside of their physical education sessions at school. An independent researcher who was not involved in any other aspect of the study randomly assigned the children to either an experimental group (EG, n = 10) or a control group (CG, n = 10). The EG participated in our novel 8-week physical training program, while the CG did not participate in any training program. A participant flow chart is given in Figure 1.

Figure 1.

Participant Flowchart.

Ethical Considerations

We explained the experimental protocol to all participants, their parents, and the directors of the schools from which participants came. After an introductory presentation and before any child’s participation in the study, parents of all participants gave their informed written consent, and children gave their assent. The research protocol was approved in advance by our local ethics committee, the “Personal Protection Committee” under the code, N°: 0324/2021.

Research Design and Procedure

This was a randomized controlled trial. The experimental protocol consisted of measurements of all participants’ physical fitness performance (lower limbs strength, functional mobility, flexibility, and muscle power) at three time points: baseline, after the intervention period, and at 3-months follow-up. Two trained professional experimenters who were unaware of the participants’ group assignments conducted all evaluations.

The 8-week training program for the EG consisted of three 60-minute sessions per week. Within each EG training session, there was a 10-minute warm-up, 45 minutes of proprioceptive and strength exercises, and a 5-minute cool down. All test measurements were performed in the mornings by the same two evaluators. Participants performed a familiarization session before the experimental protocol began, including the administration of all outcome measures to eliminate any initial performance issues related to anxiety about using new equipment and to ensure the correct execution of the tests. During this session, we also collected all participants’ anthropometric data. During experimental sessions, the examiner conducted a demonstration of the task and motivated and encouraged the children to execute the tests correctly.

Physical Fitness Measures

Lower Limbs Strength

All children performed three maximal voluntary contractions (MVC) of the quadriceps femoris muscle group with strong encouragement. This is the greatest amount of tension that a muscle can generate and sustain, briefly measured with strain gauge tensiometers (dynamometer) (Bohannon, 2005). During the testing session, the participants were seated on an isometric dynamometer (Good Strength, Metitur, Finland) equipped with a cuff attached to a strain gauge. Children stabilized themselves by grasping handles on the side of the chair during contractions. Seat belts were secured over the chest, thighs, and hips to prevent lateral, vertical, and frontal displacement. All measurements were taken from the child’s dominant leg, with hip and knee angles set at 90° of full extension (=0°). All children included in the study presented their right leg as the dominant leg (determined by the leg used to kick a ball).

Functional Mobility

We used the popular Timed Up and Go Test (TUGT) to assess our participants’ functional mobility and dynamic balance (Chomoriti et al., 2021; Moiniafshari et al., 2022; Oliveira et al., 2021). The TUGT has shown strong intra- and inter-rater reliability values when used with children and adolescents with ASD (Martín-Díaz et al., 2023). This test measures the time a child takes to get up from a chair, walk three meters, turn around, return to the chair, and sit back down. We used an adjustable height bench to allow for a 90° angle of the hip and knee, and we used a cone to mark the 3-meter distance. Children were instructed to walk at their habitual speed and to avoid running. We recorded the time spent to complete the task in seconds using a stopwatch (Martin et al., 2017). The shorter the time spent, the better the functional mobility.

Flexibility

We relied on the Sit and Reach Test (SRT) that has been previously used to assess flexibility in children with ASD (Akyol & Pektas, 2018; Cai et al., 2020; Haghighi et al., 2022). The SRT has been shown to have moderate to excellent reliability in children with ASD (Bremer & Cairney, 2019). For this test, the child was seated on the floor with legs extended and feet flat against the sit and reach box, positioned at 23 cm away. For this assessment, children were asked to lean forward as far as possible with their hands on top of each other, and we took measurements of their reach to the nearest 0.5 cm. We provided standard verbal encouragement during and after the test (e.g., “reach, reach, reach,” “good job”), and we repeated the SRT three times and selected the child’s best score for later analysis (Monyeki et al., 2005). Children were given a 2-minute sit and reach exercise after the test was completed.

Muscle Power

We used the counter-movement jump performance (CMJ) to evaluate the children’s vertical jump height (Haghighi et al., 2022). Between the two sensors of the opto-jump (Optojump, Microgate, Milan, Italy), children were required to remain in an upright position prior to the execution of the vertical jump, which began with a counter-movement until the legs were bent at 90° which signified that they could take their momentum before performing a vertical jump, seeking to go as high as possible (Bosco et al., 1983). Each participant performed three CMJs and the child’s best score was selected for later analysis. The CMJ is a valid and reliable method to measure leg power and explosiveness in children (Acero et al., 2011; Focke et al., 2013). This test was previously used in children with disabilities, including those with intellectual disability (Hassani et al., 2013), cerebral palsy (Drumm et al., 2022), and ASD (Abaza et al., 2020).

Physical Training Intervention Program

Our 8-week physical training program included proprioception and muscle strengthening exercises (Table 1). Each training session was composed of 5–8 exercises, including both proprioceptive and strength exercises (ex: air squat, wall squat, squat jump, step up) that targeted lower extremities without additional load. For the proprioceptive exercises, static and dynamic balance activities emphasizing somatosensory awareness (e.g., walking on a line, forwards, backwards and sideways on foam surface, alternate lifting of the lower extremity bent at the knee joint on trampolines) were performed on firm and different foam surfaces. Basic equipment used consisted of two mini-trampolines, proprioceptive boards, foam mats of different thicknesses and balls. The exercises were performed first by the instructor while the participant observed and performed it later with verbal corrections. The overall training volume was increased progressively by increasing the number of sets and repetitions every two weeks.

Table 1.

Experimental Training Program Exercises.

Exercises	Description of exercises
Air squat	Air squats are simply squats done without additional weights, just using one’s own body weight for resistance
Squat jumps	The participant should be standing, the movement beginning with knee flexion and extension up
Wall squat	Lean against a wall, slide down until your knees form a 90-degree angle, and then return to the starting position
Step-ups	Stand in front of a step or thick foam, place one foot on it, and then raise the opposite leg
Knee raises	Lifting your knees alternately towards your chest on a trampoline
Trampoline jumps	Jumping on a trampoline with both legs
Tuck jump with knees up	Start in a standing position, slightly bending your knees. Hold your hands out at chest height. Lower your body quickly into a squat position, then explode upwards bringing your knees up toward your chest
Two-foot ankle hop	Start standing straight up. Using only your ankles (and calf muscles), hop (jumping) repeatedly in place
Single-foot side-to-side ankle hop	Begin by standing on one leg next to one of the marks on the ground. Hop back and forth between the marks on the floor, landing on your right foot near the right mark and your left foot next to the left mark
Standing long jump	Standing behind a line marked on the ground with feet slightly apart. The objective is to jump as far as possible, landing on both feet without falling backward
Walking on line	Walking on a line, forwards, backward and sideways on different foam thicknesses surfaces
Double leg hops	Start with a double-legged hop, lowering your arms for power and then exploding upward. Aim to achieve maximum height and distance in each of your 3 or 4 jumps
Single leg hops	The same exercise but with one leg. Hop forward, jumping and landing on the same leg
Standing on two or one foot	Try to stand on two or one foot for 5–10 seconds on a proprioceptive board
Lateral jump with both feet	Begin by standing on both legs with your hands on your waist or at your sides. Hop to the side while maintaining your balance, then hop back to the starting position
Lateral jump with one foot	The same exercise but with one leg
Running up the stairs with both feet	Stand with your feet shoulder-width apart. Attempt to jump with both legs simultaneously from one stair to the next

Given that children’s participation in physical activities is enhanced by promoting intrinsic motivation (Alderman et al., 2006), the intervention consisted of three different themes, beginning with a warm-up, followed by proprioception and muscle strengthening exercises and ending with some competitive games. The training program was supervised by two professional adaptive physical activities instructors. The instructions were repeated until the participant could perform the task properly. If participants could not complete an exercise, it was canceled. Children were positively reinforced verbally with compliments for every successful trial and every effort. Further, daily and weekly improvements in skills were visualized with graphs, scales and photos at home in the child’s bedroom. Participants were considered as having completed the training program if they attended a minimum of 90% of the training sessions.

Statistical Analysis

We presented data as means (and standard deviations), and we performed calculations and analyses with Statistica for Windows software (version 8.0; StatSoft, Inc, Tulsa, OK). Data distribution normality was confirmed with the Shapiro–Wilk W test. Independent samples t-tests were executed to analyze group differences for participants’ age, height, and weight (Table 2). Statistical analyses of the outcome measures for lower limbs strength and power, functional mobility, and flexibility were performed using a two-way analysis of variance (ANOVA) with repeated measures [2 Groups (EG vs. CG) × 3 Time periods (Before Training; After Training; Follow-up)]. For each significant main factor and interaction effect, we applied a post hoc (Bonferroni) test. In addition, we calculated the effect size as partial eta squared (η²_P). This index varies between zero and 1, and we used the following interpretive guides developed by Jacob (1988): small effect size: .01 < η²_P < .06; medium effect size: .06 < η²_P < .14; large effect size: η²_P > .14. We set the level of significance for all statistical analyses at p < .05. To evaluate the changes in physical fitness components scores after training, we calculated percentage change scores or ∆ (%) using the formula: ∆ changes (%) = [(post-pre)/pre]×100.

Table 2.

Participants’ Anthropomorphic Characteristics and Tests Showing No Significant Group Differences.

	Age (years)	Height (cm)	Weight (kg)	Medication
EG	9.6 (1.9)	147.7 (13.1)	43.15 (13.8)	No medication
CG	10.1 (2.1)	157.4 (11.8)	47.8 (13.3)	No medication
Independent sample t-tests t ₍₁₈₎ =	−0.5 (p = .61)	−1.74 (p = .09)	−0.76 (p = .45)	—

Note. Values are presented as means (and standard deviations). EG, experimental group; CG, control group.

Results

Concerning lower limbs strength, the two-way ANOVA revealed no significant effect for Group (F _{(1, 18)} = 2.44; p = .13; η²_P = .11). However, there was a significant main effect of Time (F _{(2, 36)} = 7.84; p = .0014; η²_P = .30) and there was a significant Group × Time interaction effect (F _{(2, 36)} = 8.74; p < .001; η²_P = .32) on the MVC values. Post hoc testing revealed no significant differences between the groups before training, but, MVC values increased significantly only in the EG after training (p = .003; 36.98%) (Table 3). At follow-up, MVC performances decreased in the EG, regressing back to a non-significant difference from baseline (Table 3).

Table 3.

Means (M), Standard Deviations (SD) and Effects of the Physical Training on Lower Limbs Strength (MVC), Functional Mobility (TUGT), Flexibility (SRT) and Muscle Power (CMJ) in the Control Group (CG) and the Experimental Group (EG).

	Groups m (SD)
	CG (n = 10)			EG (n = 10)
	Before training M (SD)	After training M (SD)	Follow-up M (SD)	Before training M (SD)	After training M (SD)	Follow-up M (SD)
MVC (N)	78.08 (51.49)	76.71 (50.64)	77.58 (52.14)	106.84 (49.43)	135.76 (62.40)^**	96.03 (45.8) NS
TUGT (s)	10.30 (1.7)	9.68 (.96)	9.5 (.97)	8.73 (1.56)	6.36 (.86)^***	7.42 (1.24) NS
SRT (cm)	−23.1 (7.51)	−23.5 (7.8)	−23.1 (7.29)	−15.8 (13.39)	−7.1 (11.48)^***	−13.4 (15.19)NS
CMJ (cm)	11.08 (3.15)	11.01 (3.17)	11.05 (3.13)	11.16 (2.61)	15.35 (3.71)^***	14.43 (3.09)⁺⁺⁺

Note. MVC, maximal voluntary contractions; TUGT, timed up and go test; SRT, sit and reach test; CMJ, counter movement jump.

*Significant difference between before and after training: ^**p < .01; ^***p < .001.

⁺Significant difference between before training and follow-up: ⁺⁺⁺p < .001.

NS, non-significant difference between before training and follow-up.

For the TUGT, the two-way ANOVA showed significant main effects for Group (F _{(1, 18)} = 38.04; p < .001; η²_P = .67) and Time (F _{(2, 36)} = 9.86; p < .001; η²_P = .35). There was also a significant Group × Time interaction effect (F _{(2, 36)} = 9.74; p < .001; η²_P = .35). Post hoc Bonferroni analysis revealed no significant difference between the two groups at baseline before training, but post training TUGT scores decreased significantly (p < .001; 25.56%) only in the EG (Table 3). For the EG, there was no significant difference between pre-intervention and follow-up TUGT scores, and a significant (p = .034) difference was found between post-intervention and follow-up (Table 3).

Regarding the SRT scores, the two-way ANOVA revealed significant main effects for both Group (F _{(1, 18)} = 5.32; p = .033; η²_P = .22) and Time (F _{(2, 36)} = 15.55; p < .001; η²_P = .46) as well a significant Group × Time interaction effect (F _{(2, 36)} = 14.80; p < .001; η²_P = .45). Post hoc testing showed no significant difference between the two groups at baseline, but, after training, SRT scores increased significantly (p < .001; 32.46%) only in the EG (Table 3). At follow-up, SRT performance decreased (p < .001) in the EG and regressed back to the baseline level (Table 3).

For the CMJ performance, the two-way ANOVA revealed no significant main effect of Group (F _{(1, 18)} = 3.83; p = .066; η²_P = .17), but there was a significant main effect for Time (F _{(2, 36)} = 13.20; p < .001; η²_P = .42) and a significant Group × Time interaction effect (F _{(2, 36)} = 14.01; p < .001; η²_P = .43). Post hoc testing revealed no significant difference between the two groups before training, but, after training, CMJ values increased significantly (p < .001; 41,78%) only in the EG, when compared to baseline (Table 3). In the EG, no significant difference was found between the post-intervention and follow-up, but there were significantly better (p < .001) performances on the CMJ test at follow-up compared to pre-intervention (Table 3).

Discussion

We conducted the present study to explore the effects of physical training on physical fitness in children with ASD, expecting improvements in physical fitness after a novel intervention program that combined strength exercises and proprioceptive training. Our main findings showed these expected physical fitness outcomes (i.e., greater lower limbs strength and power, flexibility and functional mobility) in our EG participants but not in our CG participants who received no training. Of importance, however, the gains we observed among these children at our post-testing time point immediately after training were generally lost at our follow-up testing three months after the training had ceased.

Our data regarding the effects of our physical program, including functional strength and proprioceptive exercises, supported an expected initial increase in participants’ lower extremities muscle strength and power. As these gains did not occur for the control group participants, they appeared to be due to the strength and power exercises included in the training program when compared to no training in the CG. As explained in previous studies, the strength training exercises seem to lead to specific neural adaptations that probably result in better recruitment and more synchronized discharge of the different motor units, and in improved motor units coordination (Delecluse, 1997; Gabriel et al., 2006). Similar to our findings, others have reported that physical training combining both strength and proprioceptive exercises enhanced lower limb strength in children (Kachouri et al., 2016) and adolescents (Borji et al., 2023) with intellectual disability. In children with ASD, others also showed that physical activity intervention improved muscular strength (Pan et al., 2017; Yilmaz et al., 2004). In this context, Pan et al. (2017) explored the effect of a motor skill intervention on fundamental motor skill proficiency and showed improvement on measures of strength and agility. Yilmaz et al. (2004) evaluated the effect of water exercises and swimming on motor performance and physical fitness and demonstrated that swimming training increased lower extremity power measured by the standing broad jump in children with ASD. Furthermore, a combined physical training intervention (resistance, ball games and rhythmic movements) improved upper body strength and lower extremities explosive power in children with ASD (Haghighi et al., 2022). Others reported that higher strength levels in children can be related to higher motor proficiency (Haga, 2009; Wright et al., 2020) and might enhance performance in daily life activities. More future investigations on the effect of strength exercises in children with ASD are needed to support these assumptions.

Our findings also showed that physical training improved initial functional mobility as indicated by a significant decrease in the TUGT scores of children with ASD who underwent our training program. It is important to note that improvement in functional mobility may further promote the important functional daily activity of walking in children with ASD. In fact, the TUGT is a measure of a person’s mobility using three commonly performed functional activities of daily living: standing and sitting, walking, and turning (Podsiadlo & Richardson, 1991), and this task requires both static and dynamic balance (Ambrose et al., 2013). The reason for the significant improvement in mobility performance observed in the current study may be related to having combined strength exercises with proprioceptive ones, possibly due to enhancement in integrating proprioceptive inputs promoting postural balance control during mobility. However, since our CG received no training, we cannot be sure that our combined training program was more effective than any other training program.

Resistance exercises in the current intervention program may have been responsible for our participants’ increased flexibility, as also reported in previous studies (Barbalho et al., 2017; Morton et al., 2011). The mechanisms underlying this enhancement might be a reduction in passive tension and the stiffness of tissues surrounding a joint, increased muscle fascicle length and/or reduced pain sensitivity, as Afonso et al. (2021) previously explained. Pan (2011) provided evidence that an aquatic program could promote flexibility in children with and Bremer and Cairney (2019) showed that a fitness program improved flexibility in children with ASD children, while Tezcan and Sadik (2018) showed significant SRT improvement following a game-based training program in individuals with ASD.

Despite these several studies offering evidence that children with ASD can benefit broadly from various methods of physical training, our results reveal that these functional gains may be fragile and subject to regression on follow-up assessment after a short period of only three months after training has ceased. Our findings confirmed the necessity of promoting a lifestyle change that results in habitual participation in physical activities if the improvements in physical fitness from physical exercises seen in children with ASD are to be maintained. Of course, this is a particularly challenging goal, since similar regressions in gains have been seen even among typically developing children (Ingle et al., 2006; Qi et al., 2019). Though, Pan et al. (2017) showed that gains in motor proficiency after a motor skill intervention in children with ASD appeared to have been sustained for at least 12 weeks. Perhaps the degree of strength, power, or neuromuscular skill required to perform a selected movement may influence the long-term response of physical activity training in young children. Further research in this area is needed. Meanwhile, our results offer needed data for physical education teachers, youth coaches, and pediatric physical therapists regarding the importance of regular physical training or some type of maintenance training to preserve training-induced gains in selected measures of physical fitness in ASD children.

Limitations and Directions for Further Research

Among the limitations of our study that should be considered in their interpretation is that we excluded children with severe autism or severe intellectual disability levels from participating in this study because our program and assessment methods required stronger relational skills and mental engagement from our participants. We also relied upon a very small number of participants, meaning that the generalizability of these findings to other populations of children with ASD can be questioned. Future investigators will need to address both concerns by replicating this work with larger and more diverse participant samples and, perhaps, by adapting training and testing methods for children with more severe symptoms of autism. Moreover, we did not separately evaluate the effectiveness of this training program for children of different intelligence levels. We obtained the intelligence level from the participants’ medical files and used it only to determine eligibility for participation. Future investigators might include IQ assessment in the experimental protocol for all participants. Furthermore, this research would benefit from the inclusion of a second intervention group who practiced only strength training (i.e., without proprioceptive exercises) to isolate the bases in the intervention for the improvements we observed. Most importantly, future investigators will need to address problems with the sustainability of exercise benefits in intervention programs designed for children with ASD and begin to discern what level of continued physical activity may be needed to sustain early benefits.

Conclusions

Findings from this study suggest that a physical training program that specifically included strength and proprioceptive exercises helped promote physical fitness in children with ASD. However, very importantly, we also showed that these notable beneficial effects generally disappeared after three months follow-up when participants were no longer involved in physical training. Considering that children with ASD often have low functional motor performance, it is strongly recommended that they be engaged early in such interventions as ours. In fact, therapists working with these children should work to insure that they have access to such a training program, partly as a means of increasing their independence in activities of daily living. Physical education classes break times, and after-school hours are among the best times to get children engaged in physical activity (Sandt & Frey, 2005). In this regard, physical education teachers and instructors are recommended to take maximum advantage of these hours to help rehabilitate children with ASD children, as some of them may not have the opportunity to undergo similar programs outside of their school. Additionally, based on our results, professionals who prescribe this type of training for children with ASD should consider the negative consequences of training cessation on these children’s subsequent performance and well-being. To develop and maintain fitness proficiency, children with ASD should be encouraged to participate regularly in physical training lessons, and further research is needed to address motivational concerns and other barriers to achieving this goal.

Footnotes

Acknowledgments

We thank all the participants for their understanding and availability.

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

ORCID iDs

Malek Belaiba

Rabeb Laatar

Amani Ben Salem

Author Biographies

Malek Belaiba (PhD student) is currently pursuing her PhD in the biological sciences of physical activities and sports at the High Institute of Sport and Physical Education of Sfax, Tunisia. Her research relates the variables of physical exercise and people with disabilities.

Rabeb Laatar is currently professor of biological sciences at the University of Gafsa, Tunisia. Her research field is the Adapted Physical Activity.for disabled populations.

Rihab Borji is currently professor of biological sciences at the University of Sfax, Tunisia. Her research field is the Adapted Physical Activity for disabled populations.

Amani Ben Salem (PhD student) is currently pursuing her PhD in the biological sciences of physical activities and sports at the High Institute of Sport and Physical Education of Sfax, Tunisia. Her research relates the variables of physical exercise and people with disabilities.

Sonia Sahli is a professor of biological sciences at Sfax University, Tunisia. She is director of the education, motricity, sport and health laboratory. Her research is based in the fields of sports science and public health.

Haithem Rebai is a professor of biological sciences at Sfax University, Tunisia. His research is based in the fields of sports science, sports performance and public health.

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