The elderly commonly experience deterioration in the visual and proprioceptive systems, which can impact balance and postural control [1,2]. In older adults, proprioceptive information plays an important role in maintaining balance. Other studies [3,4] have underscored the role of balance training in improving proprioception and dynamic balance. The balance training type can enhance ankle stability (i.e., lower limbs function), neuromuscular function (i.e., related to strength), and postural control system efficiency [5,6]. This highlights the significance of incorporating balance exercises targeting proprioception in older adults to enhance dynamic balance and reduce the risk of falls [7]. Finally, [8] identified a link between sleep quality and dynamic balance, indicating that poor sleep quality may be associated with dynamic imbalance in older adults. However, the authors were unable to evaluate the effects of training exercise programs on physical fitness, sleep quality, and balance.

The relationship between sleep quality and physical exercise in older people has been widely documented in the literature. Studies have shown that aerobic exercise can improve self-reported sleep and quality of life in older adults with insomnia [9]. Additionally, systematic reviews have indicated that physical activity programs positively impact various aspects of sleep in generally healthy older adults [10]. A study [11] showed that in community-dwelling older adults, exercise can impact sleep through mechanisms such as light exposure, temperature regulation, and mood. A recent systematic review and meta-analysis have further supported the positive effects of physical exercise programs on improving sleep quality in older adults [12]. However, a longitudinal study demonstrated that sleep quality plays a crucial role in older adults’ level of physical activity, with better sleep quality promoting more physical activity [13]. Older individuals often struggle with changing positions during sleep due to musculoskeletal pain, decreased mobility, and motor impairments [14,15], leading to discomfort and sleep disturbances [16]. Also, chronic pain conditions and limited ability to change positions worsen sleep difficulties [17], compounded by physical disabilities and cognitive impairments [15]. Poor sleep quality is independently linked to physical disability and functional limitations in older adults [18,19], stressing the need to address sleep disturbances to enhance overall health and well-being [18,20]. Upon that, physical exercise training programs may improve body functionality and possibly sleep quality. Between the different exercise training programs, the American College of Sports Medicine (ACSM) previously highlighted the importance of multicomponent training (MCT) for older adults, citing its benefits for strength, aerobic fitness, and balance [21]. This type of program (MCT) including exercises for aerobics, resistance, balance, and flexibility composes the multicomponent training [22,23]. It could improve metabolic outcomes, functional and cognitive performance, cardiorespiratory fitness and autonomy. The fundamental part of each training session aims to train aerobic, resistance, and balance skills [22,23]. Subsequent research has supported these claims. A review of 27 studies showed that MCT improves physical fitness and overall health in older populations [24]. Additionally, a meta-analysis comparing aerobic training, resistance training, and MCT found MCT to be the most effective for cognitive improvement [25]. Recent research also supports MCT’s positive effects on attention and executive function in older adults [26]. MCT programs include exercises targeting physical and cognitive health [5,27,28], aiming to enhance muscle mass, power output, functional outcomes, cognitive function, and brain health [6,29]. Overall, MCT appears effective in improving physical function, muscle mass, cognitive function, and mental health in older adults, even those with conditions like mild cognitive impairment, dementia, Alzheimer’s disease, and sarcopenia [28,30].

The relationship between exercise, physical fitness, body composition, and sleep quality in older adults may be complex and interconnected [31,32]. In light of the above, it seems important to continue investigating to understand the complexity of the phenomenon to broadly understand the effects of exercise on sleep quality and its associations with physical fitness and body composition, which can play a fundamental role in the development of interventions that promote healthy aging and improve the well-being of older individuals. Given this, this research aimed to evaluate the effects of 8 months of multicomponent training programs on critical variables such as physical fitness, body composition, and sleep quality. Additionally, we aim to seek the associations between physical fitness, body composition, and sleep quality. It was hypothesized that an 8-month multicomponent training program would significantly positively affect physical fitness, body composition, and sleep quality.