INTRODUCTION
The rapid advancement of modern technology and the concomitant increase in sedentary lifestyles have contributed to a continuous rise in the prevalence of obesity (Chooi et al., 2019). Obesity is defined as excessive accumulation of body fat and is associated with various comorbidities, including cardiovascular, metabolic, and musculoskeletal disorders (Khalafi et al., 2023; Park et al., 2020). Furthermore, obesity may impair physical function, particularly balance, due to altered proprioception and increased mechanical loading (Capodaglio et al., 2021).
Exercise is considered an effective non-invasive strategy for managing obesity, as it improves body composition and physical fitness, including muscular strength, core stability, and balance (Berry et al., 2013; Pedersen, 2017). Among various modalities, weight-bearing exercise has been widely used to enhance muscular strength and promote fat loss (Brellenthin et al., 2019). However, low exercise adherence, particularly among women with obesity, highlights the need for alternative modalities that can improve engagement and sustainability (Grünebaum and Dudenhausen, 2022; Martinez Kercher et al., 2024).
In this context, ballet-based exercise has recently emerged as a promising alternative modality that may improve both engagement and adherence. Ballet exercise is a whole-body activity that requires flexibility, balance, muscular strength, and joint range of motion, while continuously demanding core stability and postural control (Letton et al., 2024). Notably, ballet movements involve repetitive muscle contractions and multi-joint actions under weight-bearing conditions, which can increase energy expenditure and activate various muscle groups. These characteristics suggest that ballet exercise may provide benefits comparable to weight-bearing exercise while additionally improving balance and core function (Lepelley et al., 2006).
However, existing studies have primarily focused on trained dancers or healthy individuals, and investigations targeting individuals with obesity remain limited, particularly in terms of integrated outcomes such as body composition, physical fitness, and isokinetic muscle function. In addition, few studies have directly compared ballet exercise with conventional weight-bearing exercise using comparable training durations and intensities, making it difficult to determine their relative effectiveness.
It is hypothesized that ballet exercise will produce improvements in body composition and physical fitness comparable to weight-bearing exercise, with additional benefits in balance and core function. Therefore, the purpose of the present study was to compare the effects of an 8-week ballet exercise program and a weight-bearing exercise program on body composition, basic physical fitness, and isokinetic knee muscle function in women with obesity.
MATERIALS AND METHODS
Experimental design
This study was conducted on 23 obese women aged between 20 and 30 years who had no history of cardiovascular disease or vestibular disorders and a body fat percentage of 30% or higher. Sample size was calculated using G*Power (ver. 3.1.9.7) with an effect size of 0.40, α=0.05, and power=0.80, resulting in a required minimum sample size of 21 participants. Considering a potential dropout rate of 30%, a total of 30 participants were initially recruited. During the intervention period, seven participants withdrew, and thus 23 participants were included in the final analysis. Participants were randomly assigned to three groups: the control group (CG, n=7), the ballet exercise group (BEG, n=10), and the weight-bearing exercise group (WBEG, n=6). Randomization was performed using a computer-generated random allocation sequence. The study protocol was approved by the Institutional Review Board of Jeju National University (JJNU-IRB-2024-001). The physical characteristics of the participants are presented in Table 1.
Ballet and weight-bearing exercise program
The ballet and weight-bearing exercise program are presented in Table 2. Two types of exercise programs were conducted for 60 min per session, 3 times per week, for 8 weeks. Exercise intensity was regulated using the rating of perceived exertion (RPE) scale, and was progressively increased throughout the intervention period. Specifically, the warm-up and cool-down were performed at an RPE of 9–10, while both the ballet exercise and weight-bearing exercise were performed at an RPE of 13–14 during weeks 1–4 and increased to 15–16 during weeks 5–8. To ensure comparable exercise intensity between the two intervention groups, both programs were designed to follow the same RPE ranges, session duration, and frequency. In both exercise groups, each exercise was performed for 12–15 repetitions per set, with a 1-min rest interval between sets. Prior to the main intervention, a 1-week familiarization period was provided to accommodate participants who had no exercise experience for at least 3 months. The ballet exercise program and weight-bearing exercise program were developed and modified based on previous studies (Kim et al., 2018; Letton et al., 2020). Participants were instructed to maintain their usual dietary intake and daily physical activity throughout the intervention period and to refrain from additional structured exercise. However, dietary intake and physical activity were not strictly controlled, which may be considered a limitation of this study.
Body composition
Height and body composition were measured using an automatic stadiometer (GL-310B, G-tech, Korea) and a bioelectrical impedance analyzer (InBody 270, InBody, Korea), respectively. Weight, percent body fat (%Fat), and skeletal muscle mass (SMM) were obtained from the analysis.
Basic physical fitness
Muscle strength was assessed using a back strength dynamometer (T.K.K. 5402, Japan), and the highest value from two trials was recorded to the nearest 0.1 kg. Flexibility was measured using a sit-and-reach test (T.K.K. 5111, Takei), and the maximum value from two trials was recorded to the nearest 0.1 cm. Muscular endurance was evaluated using a sit-up in which participants performed as many repetitions as possible within 1 minute on a measurement device (T.K.K. 5505, Takei). Power was assessed using the Sargent jump test (DW-771A, Daewoo Sports Industry, Korea), and jump height was recorded. Dynamic balance was measured using a Y-Balance Test Kit (Move2Perform, USA). Lower-limb length was measured from the anterior superior iliac spine to the medial malleolus, and each reach direction was tested 3 times. The results were expressed as normalized values and composite scores.
Isokinetic knee muscle function
Isokinetic knee muscle function was assessed using an isokinetic dynamometer (Humac Norm 776, CSMI, USA). Isokinetic muscle strength was measured at an angular velocity of 60°/sec for 3 repetitions, whereas isokinetic muscle endurance was assessed at 240°/sec for 12 repetitions over a range of motion from 0° to 100°.
Statistical analysis
All statistical analyses were performed using IBM SPSS Statistics ver. 24.0 (IBM Co., USA). Descriptive statistics are presented as mean±standard deviation. A one-way analysis of variance (ANOVA) was conducted to compare baseline physical characteristics among groups. A two-way repeated measures ANOVA was conducted to examine the interaction effects between group and period for all variables. In addition, paired t-tests were performed to assess within-group changes over period. The level of statistical significance was set at 0.05.
RESULTS
Comparison of body composition
As shown in Table 3, body weight and %fat showed significant reductions over time only in the BEG (P<0.05 and P<0.01, respectively), whereas no significant changes were observed in the CG and WBEG. However, no significant changes were observed in SMM in any group.
Comparison of basic physical fitness
As shown in Table 4, several basic physical fitness improved over time. Back strength increased significantly in both the BEG (P<0.001) and WBEG (P<0.01). Flexibility also increased significantly in both groups, with the BEG (P<0.001) and the WBEG (P<0.05). However, no significant changes were observed in Sargent jump performance. For dynamic balance, the left anterior and left composite score improved significantly in both exercise groups (P<0.001), and right anterior, right posterolateral, right composite score (P<0.05), right posteromedial (P<0.01), left posteromedial (P<0.01), left posterolateral (P<0.001) improved significantly in the BEG. In contrast, improvements in right-sided balance variables were generally observed only in the BEG.
Comparison of isokinetic knee strength at 60°/sec
As shown in Table 5, isokinetic knee strength improved primarily in the exercise groups. At 60°/sec, significant increases in left knee extensor strength were observed in both the BEG (P< 0.001) and WBEG (P<0.01), while left knee flexor strength improved only in the WBEG (P<0.01). No significant changes were observed in the right knee. When normalized to % body weight, both exercise groups showed additional improvements in knee strength, particularly in the extensors, although these changes were not consistent across all variables.
Comparison of isokinetic knee endurance at 240°/sec
As shown in Table 6, isokinetic knee endurance improved mainly in the exercise groups. For total work done at 240°/sec, significant increases were observed primarily in the knee extensors of both the BEG (P<0.05) and WBEG (P<0.01). In addition, right knee flexor strength increased significantly in the BEG (P<0.01), whereas other flexor variables showed limited changes. For average power, significant increases were observed in the right knee in the BEG (P<0.05) and in the left knee extensor in the WBEG (P<0.05).
DISCUSSION
The present study investigated the effects of an 8-week ballet versus weight-bearing exercise programs for obese women on body composition, basic physical fitness, and isokinetic knee muscle function, and several key findings were identified. In terms of body composition, only the BEG showed a significant reduction in weight and %Fat, whereas no significant changes were observed in the CG and WBEG. Ballet involves continuous, low- to moderate-intensity movements requiring sustained muscle activation, which may contribute to increased energy expenditure over time. Such characteristics have been associated with improved substrate utilization and fat oxidation during prolonged activity (Melanson, 2017; Rodrigues-Krause et al., 2014; Willis et al., 2012). Nevertheless, the specific mechanisms underlying fat reduction in response to ballet exercise remain unclear and require further investigation.
Although no significant changes were observed in SMM—likely due to the 8-week duration—the reduction in body fat highlights the potential of ballet for obesity management. Consequently, ballet could be considered a viable option to improve body composition by reducing adiposity while maintaining lean mass in women with obesity. Regarding basic physical fitness, both the BEG and WBEG showed significant improvements in back strength, flexibility, and left-side dynamic balance, whereas improvements in sit-up performance and right-side dynamic balance were observed only in the BEG. In contrast, no significant changes were observed in lower extremity power. These findings indicate that both exercise modalities improve general physical fitness; however, ballet exercise may provide additional benefits in core muscular endurance and unilateral balance performance.
These results may be explained by the specific characteristics of ballet exercise. Ballet movements are performed with an upright posture and emphasize continuous activation of core muscles, including the rectus abdominis and erector spinae, while engaging the entire body to control limb movements (Koutedakis and Jamurtas, 2004). In addition, ballet incorporates specific balance-challenging postures such as the passé and arabesque, which require simultaneous engagement of flexibility, posterior chain strength, and postural control (Hagins et al., 2021). Furthermore, ballet is generally divided into bar and center exercises. While bar exercises involve external support and relatively limited displacement of the center of mass, center exercises are performed without support and include various unilateral and multi-planar movements, resulting in greater shifts in the center of mass and increased demands on postural control (Letton et al., 2024). These characteristics are considered key components of balance training and have been shown to improve balance ability (Sherrington et al., 2017). Since obesity often leads to decreased physical function, partly due to impaired proprioception and increased mechanical loading, which can compromise postural balance (Capodaglio et al., 2021), the multifaceted movements of ballet could be particularly effective. By addressing these functional deficits, ballet exercise can be recommended as a viable modality to enhance stability and overall physical function in women with obesity.
Isokinetic muscle function reflects a muscle’s capacity to generate force at a constant angular velocity, providing an objective measure of both strength and endurance under controlled conditions while evaluating force production throughout the full range of motion relevant to functional activities (Wilk et al., 2024). This measure is particularly important in individuals with obesity, as excess body weight increases mechanical loading on the lower limbs and may compromise joint stability, balance, and mobility (Hulens et al., 2002). Adequate knee extensor strength and endurance are therefore essential for supporting body weight during daily activities and reducing the risk of musculoskeletal injury (Lue et al., 2000).
Regarding isokinetic knee muscle function, both the BEG and WBEG showed significant improvements in knee extensor strength and muscular endurance, with comparable gains between groups. These findings suggest that ballet exercise can enhance lower-limb muscle function as effectively as weight-bearing resistance training. Such improvements may be attributed to ballet’s emphasis on postural alignment and continuous neuromuscular control, which promotes coordinated muscle activation across multiple planes of motion. In women with obesity, this integrative stimulus likely optimizes muscle recruitment patterns while minimizing excessive joint stress. Therefore, both exercise modalities appear to be effective strategies for improving lower-limb muscle performance, functional capacity, and joint protection in this population. Taken together, the findings of this study suggest that ballet exercise is associated with improvements in body composition, core strength, balance, and isokinetic knee function in women with obesity. Comparable changes were observed between the exercise groups in isokinetic muscle function, while additional improvements in core endurance and unilateral balance were observed in the BEG.
Despite these findings, several limitations should be acknowledged. The relatively small sample size, short intervention duration, and lack of strict dietary control may limit the generalizability of the results. Future studies with larger samples, longer intervention periods, and controlled dietary conditions are warranted.
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