Efficacy of a weighted-vest aerobic dance intervention for enhancing lower extremity strength and mobility in older adults: a randomized controlled trial

Abstract

[Purpose]

To investigate the effectiveness of an 8-week aerobic dance program combined with a weighted vest on functional fitness, body composition, and bone mineral density (BMD) in postmenopausal women with low bone mass.

[Methods]

Fifty-seven participants (60-80 years) were randomized to perform 50-minute aerobic dance sessions (3 days/week for 8 weeks) either alone (AD, n = 28) or while wearing a 7% body mass weighted vest (AD + WV, n = 29). The outcomes included the Senior Fitness Test, body composition, BMD, and resting blood pressure.

[Results]

After the 8-week intervention, the AD + WV group demonstrated a significantly greater increase in lower body strength (30-second chair stand), with a 38.1% increase, compared to an 11.3% increase in the AD group (interaction p = 0.002). Dynamic mobility (Timed Up and Go) showed no significant time (p = 0.477), group (p = 0.327), or interaction (p = 0.546) effects. Additionally, both groups showed equivalent reductions in resting systolic and diastolic blood pressure, which were statistically significant (p < 0.05). There were no significant changes in total muscle mass or BMD in either group (p > 0.05), and no training-related injuries were observed.

[Conclusion]

Adding a 7% weighted vest to aerobic dance safely and effectively enhances lower body strength in older women with low bone mass. The absence of short-term structural changes suggests improvements may stem from multiple mechanisms, including neuromuscular adaptations, warranting further investigation. This intervention may represent an adjunctive strategy for improving functional capacity related to fall risk, though this potential benefit requires confirmation in future studies.

INTRODUCTION

At present, the rate of aging is increasing globally, resulting in more cases of musculoskeletal diseases, particularly among older people. According to recent national data, approximately 38.5% of Thai older adults living in communities are at high risk of falls, which may be worsened by existing musculoskeletal problems, including osteoporosis and sarcopenia [1]. Patients with low bone mass, who have low bone density, are highly susceptible to fractures. These consequences may not only reduce their ability to function independently but also lead to substantial burdens on healthcare [2]. Therefore, there is a need to explore possible methods of intervention to improve physical fitness and minimize the risk of falls among these patients.

The aerobic dance routine is an exercise form that is popular among older adults because of its rhythm and social nature, along with its positive effects on the cardiorespiratory system [3,4]. However, scientific research suggests that exercising solely through aerobic activities will lead to a plateau in the enhancement of muscle strength and body composition if there is no continued resistance load [5]. With respect to the fact that the main factors predicting falls are lower extremity strength and dynamic balance, it can be assumed that a regular bodyweight-based aerobic dance program will become insufficient at some point in time to ensure the mechanical overload necessary for improving physical function to mitigate fall risk.

The use of weighted vests (WV) has emerged as a practical, lowcost, and safe method for applying external loading during functional movements [6]. Unlike other resistance modalities, such as elastic bands or handheld weights, a weighted vest allows hands-free exercise, enabling older adults to execute the complex choreography and balance-challenging movements inherent in aerobic dance without compromising postural stability. This modality applies the overload principle while maintaining the dynamic, multiplanar nature of rhythmic exercise. Recent pilot studies have demonstrated that incorporating weighted vests can significantly improve postural stability and balance-related quality of life in older adults [7]. Despite these potential benefits, the specific efficacy of integrat-ing a weighted vest into a structured aerobic dance routine for postmenopausal women with low bone mass remains unclear.

While significant bone structural remodeling typically requires long-term intervention, substantial improvements in functional strength can be achieved within shorter durations through neuromuscular adaptation [8]. Resistance-induced gains in the initial phases (e.g., 8 weeks) are primarily driven by enhanced motor unit recruitment, increased firing frequency, and improved synaptic input within the neuromuscular system [9]. Therefore, an 8-week program combining aerobic dance with controlled external axial loading may provide a sufficient stimulus to augment lower limb power and functional mobility. Accordingly, this randomized controlled trial aimed to evaluate the efficacy of an 8-week aerobic dance program combined with a weighted vest compared with aerobic dance alone on muscular strength, functional mobility, and physiological parameters in postmenopausal women with low bone mass.

METHODS

Participants

This study utilized a randomized controlled trial (RCT) design. The participants included older adult women who were aged 60-80 years and lived in the community. Participants were postmenopausal women who presented with a FRAX score indicating a hip fracture probability exceeding 3% and were identified as having low bone mass using a Tanita InnerScan (Model RD-953) body composition analyzer. The participants were required to have no history of regular exercise for at least six months prior to the study, along with the ability to perform daily activities independently. The exclusion criteria included the presence of cardiovascular diseases or severe hypertension, neurological disorders affecting balance, or any orthopedic contraindications to exercise.

The sample size was estimated based on a two-group repeated-measures ANOVA (within-between interactions) with a power of 95% (beta error 0.05) and statistical significance of p < 0.05 (alpha error 0.05). The effect size (f) was set to 0.25, representing a medium effect size. Therefore, a minimum total sample size of 54 participants (27 per group) is required. After correcting for an anticipated dropout rate of approximately 10%, the total number of participants recruited at baseline was 60 (30 per group).

After providing informed consent, 60 participants were randomly divided into two experimental groups, with Group 1 being aerobic dance exercise alone (AD), and Group 2 being aerobic dance exercise with an additional load at 7% of body weight (AD + WV). Random sequence generation was performed using computer-generated random numbers on a 1:1 ratio. Allocation concealment was ensured using sequentially numbered, opaque, sealed envelopes. The randomization and allocation were conducted by an independent research assistant who was not involved in the current study, and outcome assessors were blinded to the group assignments to minimize bias. During outcome assessments, all participants wore standard clothing without a weighted vest, preventing assessors from visually identifying group allocation. Three participants withdrew from the study due to time constraints: two from the AD group and one from the AD + WV group. The flow of participants through each stage of the trial is shown in Figure 1. The research was conducted following the principles of the Declaration of Helsinki and received ethical approval from the Uttaradit Rajabhat University Ethics Committee (reference number COA No. 043/2024).

Figure 1. Participant flow diagram.

Intervention

The exercise program employed during the study was the same for both groups, conducted three sessions per week (every Monday, Wednesday, and Friday) for eight weeks, totaling 24 sessions. The aerobic dance program was led by a qualified professional. Each session lasted 50 minutes and comprised a 10-minute warm-up with rhythmic stretching, a 30-minute main aerobic dance phase tailored to the weekly rhythm, and 10 minutes of relaxing activities as a cooldown. Exercise intensity was controlled using the Borg Rate of Perceived Exertion (RPE) scale, targeting a range of 12-16. In the AD + WV group, participants performed the identical routine while wearing a custom-designed adjustable weighted vest. The external mechanical load was calibrated to exactly 7% of each participant’s baseline body weight, as determined during the first week, and was maintained throughout the 8-week trial. To adhere to the training principle of progressive overload, exercise progression was implemented after the completion of the first 4 weeks (Weeks 5-8) by transitioning to a more complex choreography composition and accelerating the musical tempo (beats per minute, BPM). Throughout the experimental period, all participants were instructed to maintain their usual lifestyle and habitual physical activity. Compliance with the intervention was strictly enforced based on the minimum attendance criterion. All 57 participants included in the final analysis completed at least 22 of the 24 sessions, representing a minimum compliance threshold of 91.7%.

Outcome Measures

The risk of osteoporotic fractures was evaluated using the World Health Organization’s Fracture Risk Assessment Tool (FRAX) [10]. This tool combines clinical risk factors such as age, sex, body weight, height, history of fractures, parental history of hip fractures, smoking status, glucocorticoid usage, presence of rheumatoid arthritis, secondary osteoporosis, and alcohol consumption, with or without the measurement of femoral neck bone mineral density, to determine the 10-year likelihood of experiencing major osteoporotic and hip fractures.

The primary outcome of this study was functional fitness, which was assessed using the Senior Fitness Test, and the secondary outcomes were physiological and body composition. Outcome measures were assessed at baseline and following the completion of the 8-week exercise program, specifically two days subsequent to the final exercise session. The assistant researchers responsible for evaluating the outcomes were blinded to group assignments. The participants underwent a familiarization test one week before the commencement of the experiment.

Upper-body muscle strength was evaluated using the arm curl test. The participants were seated on a chair and performed bicep curls with a 5-lb dumbbell using their dominant hand. The score was the total number of repetitions performed in 30 s. Lower muscle strength was evaluated using a 30-second chair stand test, which involved getting up and down from a chair as fast as possible with their arms folded across their chests. Each participant began in the same posture, with their feet flat on the floor and their hip and knee joints at a 90-degree angle. The participants were instructed to repeat this task as many times as safely possible within 30 s.

Lower body flexibility was evaluated using the chair sitand-reach test. The participants were seated at the edge of a chair with one leg extended forward, maintaining a straight knee, with the heel placed on the floor and the ankle flexed at 90°. The participants were instructed to position one hand atop the other, aligning the tips of the middle fingers. They were then directed to inhale and, upon exhalation, reach forward towards the toes by bending at the hip, ensuring that the back remained straight and the head elevated. The participants were advised to avoid bouncing or rapid movements and refrain from stretching to the point of discomfort. The knee remained straight, and the reach was sustained for 2 s. The distance between the fingertips and toes was measured. A score of zero was assigned if the fingertips touched the toes. If the fingertips did not reach the toes, the distance between the fingertips and toes was measured as a negative score, and if they overlapped, the distance was recorded as a positive score.

Upper-body flexibility was evaluated using the backscratch test. Participants performed this test in a standing position, placing one hand over the shoulder, reaching down the back, and the other hand behind the back, reaching upward, and attempting to touch or overlap the middle fingers. The distance between the fingertips (gap or overlap) was measured in centimeters (cm).

Functional mobility was assessed using the Timed Up and Go (TUG) test, which is recognized for its excellent reliability and validity in older adult populations. Participants were initially seated comfortably in a chair and instructed to rise and walk at a comfortable pace to a designated point on the floor located 8 feet away, turn around, return to the chair, and resume the initial seated position. The timing commenced when the participant began to rise from the chair and concluded upon their return to the original sitting position.

Aerobic endurance was evaluated using the 2-minute step test. The participants marched in place, raising each knee to a height midway between the patella and the iliac crest. The participants then marched in place for two minutes, attempting to lift their knees to the height of the tape. Participants were permitted to hold stable support to maintain balance, and rest intervals were allowed if necessary. The score was recorded as the total number of times the right knee reached the target height within a two-minute duration.

Heart rate and blood pressure were assessed using an automatic blood pressure monitor (Omron HEM-7154-A; Omron Healthcare Co., Ltd., Kyoto, Japan). Measurements were taken following a 15-minute rest period at the same time of day, both prior to and after an 8-week post-exercise regimen. Body mass and body composition, including bone mass estimation, were assessed using a body composition analyzer (Tanita InnerScan Model RD-953; Tanita Corp., Tokyo, Japan). The participants wore light clothing and remained barefoot during the measurement process. They stood on two footpad electrodes that were integrated into the platform. A bioelectrical impedance analyzer was used to estimate bone mass, muscle mass, and body fat percentage.

Statistical Analysis

Statistical analyses were conducted using Jamovi (version 2.7; The Jamovi Project, Sydney, Australia). Descriptive statistics are reported as mean ± standard deviation (SD). The Shapiro-Wilk and Levene’s tests were used to assess the normality and homogeneity of the data, respectively. Baseline demographic characteristics were compared using independent samples t-tests. To evaluate the effects of the intervention, a two-way analysis of variance (ANOVA) with repeated measures was employed to determine the interaction between groups (AD vs. AD + WV) and times (baseline vs. 8 weeks). The significant interaction effects were further analyzed using Bonferroni post-hoc tests. Effect sizes were quantified using partial eta-squared (η²_p), with values of 0.01, 0.06, and 0.14 defined as small, medium, and large effects, respectively [11]. Statistical significance was set at p < 0.05.

RESULTS

Data were collected from 30 participants. Two participants in the AD group and one participant in the AD + WV group withdrew due to time constraints, resulting in the control group (AD) n = 28 and the intervention group (AD + WV) n = 29 completing pre- and post-intervention data collection and intervention. No participant in either group experienced injury, discomfort, or cardiovascular events during the study period. The characteristics of the participants in each group are presented in Table 1. There were no significant differences in the characteristics, body composition, or baseline physiological variables between the two groups (AD and AD + WV), indicating that both groups were well-matched prior to the intervention. Importantly, no adverse effects or cardiovascular events were observed in any group throughout the study.

Table 1.

Characteristics and physiological variables of participants in both groups

Characteristics	AD (n = 28)	AD + WV (n = 29)	p-value
Age (years)	67.2 ± 3.3	69.7 ± 6.8	0.109
Body mass index (kg/m2)	25.8 ± 3.7	25.8 ± 5.4	0.827
Bone mass (kg)	2.2 ± 0.3	2.1 ± 0.3	0.634
Muscle mass (kg)	36.1 ± 4.0	35.9 ± 4.2	0.909
Fat (%)	34.4 ± 7.7	36.4 ± 9.3	0.295
Resting heart rate (bpm)	81.0 ± 13.5	78.9 ± 6.3	0.431
Systolic blood pressure (mmHg)	135.3 ± 15.0	136.6 ± 15.9	0.617
Diastolic blood pressure (mmHg)	82.7 ± 7.0	79.6 ± 5.8	0.078
FRAX score	6.4 ± 3.8	5.7 ± 3.2	0.427

Data are presented as means ± SD.

Physiological and Body Composition

Compared to baseline, the 8-week exercise program significantly reduced systolic blood pressure in both groups (p < 0.05), with a decrease from 135.32 ± 15.00 to 130.14 ± 12.64 mmHg in the AD group and from 136.69 ± 15.92 to 129.97 ± 13.19 mmHg in the AD + WV group. For diastolic blood pressure (DBP), a significant main effect of time was observed (p = 0.006). However, within-group analysis revealed that only the AD + WV group achieved a statistically significant reduction (79.69 ± 8.78 to 76.28 ± 8.35 mmHg, p = 0.020) in diastolic blood pressure. Despite a slight decrease in mean values, the AD group did not exhibit a statistically significant change in DBP (p = 0.096). Resting heart rate, bone mass, muscle mass, and body fat percentage did not change significantly after 8 weeks of training in either group (p > 0.05) (Table 2).

Table 2.

Heart rate, blood pressure, and body composition before and after 8 weeks of exercise in both groups

Outcome	AD (n = 28)		Mean Change	AD + WV (n = 29)		Mean Change	p-value (η₂ᵖ)
	Before	After		Before	After		Time	Group	Interaction
HR (bpm)	81.0 ± 13.5	76.2 ± 10.5	-4.8	78.9 ± 6.3	79.8 ± 5.7	0.9	0.307 (0.02)	0.655 (0.00)	0.140 (0.04)
SBP (mmHg)	135.3 ± 15.0	130.1 ± 12.6*	-5.1	136.6 ± 15.9	129.9 ± 13.1*	-6.7	< 0.001 (0.29)	0.868 (0.00)	0.545 (0.01)
DBP (mmHg)	82.7 ± 7.0	79.3 ± 9.8	-3.4	79.6 ± 5.8	76.2 ± 6.6*	-3.4	0.006 (0.13)	0.055 (0.07)	0.983 (0.00)
Bone mass (kg)	2.2 ± 0.3	2.1 ± 0.3	-0.1	2.1 ± 0.3	2.1 ± 0.2	0.0	0.353 (0.02)	0.776 (0.00)	0.247 (0.02)
Muscle mass (kg)	36.1 ± 4.0	35.6 ± 3.2	-0.5	35.9 ± 4.2	35.4 ± 2.7	-0.5	0.306 (0.02)	0.839 (0.00)	0.980 (0.00)
Body fat (%)	34.4 ± 7.7	36.1 ± 9.3	1.7	36.4 ± 9.3	36.8 ± 9.9	0.3	0.329 (0.02)	0.553 (0.01)	0.533 (0.01)

Data are presented as mean ± SD. AD, Aerobic Dance group; AD + WV, Aerobic Dance with Weighted Vest group; SBP, Systolic Blood Pressure; DBP, Diastolic Blood Pressure; HR, Heart Rate; η^₂_ᵖ = Partial eta-squared.

^*Significant difference before and after training (p < 0.05).

Functional Fitness

Paired sample t-tests were performed to determine preand post-intervention improvements within both groups. The weighted vest intervention group (AD + WV) achieved statistically significant improvements in all parameters except the Timed Up and Go test: chair stand (p < 0.001), arm curl (p < 0.001), 2-min step (p < 0.001), sit and reach (p = 0.023), and back scratch (p < 0.001) tests. In contrast, four out of six dependent variables in the control group (AD) demonstrated statistically significant pre-post intervention improvement: chair stand (p = 0.048), arm curl (p < 0.001), 2-min step (p < 0.001), and back scratch (p = 0.050). Regarding the primary outcomes, significant improvements were found in the 30-s chair stand (F_(1,55) = 11.03, p = 0.002, η²_p = 0.16) and arm curl test (F_(1,55) = 4.19, p = 0.046, η²_p = 0.07). The comparison details are presented in Table 3.

Table 3.

Functional fitness variables in AD and AD + WV groups at baseline and after 8 weeks

Outcome	AD (n = 28)		Mean Change	AD + WV (n = 29)		Mean Change	p-value (η₂ᵖ)
	Before	After		Before	After		Time	Group	Interaction
Chair stand (rep)	18.7 ± 4.6	20.8 ± 4.6*	2.1	16.9 ± 3.4	23.3 ± 4.7*	6.4	< 0.001 (0.45)	0.638 (0.00)	0.002 (0.16)†
TUG (s)	5.9 ± 1.2	5.9 ± 1.0	0.0	5.8 ± 1.1	5.6 ± 1.0	-0.2	0.477 (0.01)	0.327 (0.02)	0.546 (0.01)
Arm curl (rep)	18.1 ± 3.8	21.8 ± 4.9*	3.6	18.0 ± 3.9	24.4 ± 3.9*	6.4	< 0.001 (0.51)	0.161 (0.04)	0.046 (0.07)†
2-min step (rep)	116.5 ± 23.6	171.2 ± 53.8*	54.6	114.6 ± 35.3	193.4 ± 55.8*	78.8	< 0.001 (0.52)	0.202 (0.03)	0.171 (0.03)
Sit-and-reach (cm)	4.7 ± 2.6	5.8 ± 3.2	1.1	5.1 ± 3.2	6.5 ± 3.0*	1.3	0.017 (0.10)	0.413 (0.01)	0.789 (0.00)
Back scratch (cm)	-6.4 ± 11.6	-0.4 ± 8.4*	6.0	-4.7 ± 12.9	-0.6 ± 12.3*	4.1	0.002 (0.17)	0.790 (0.00)	0.529 (0.01)

Data are presented as mean ± SD. AD, Aerobic Dance group; AD + WV, Aerobic Dance with Weighted Vest group; TUG, Timed-up-and-go; η^₂_ᵖ = Partial eta-squared.

^*Significant difference before and after training (p < 0.05).

^†Significant TimeÍGroup interaction (p < 0.05).

DISCUSSION

The principal finding of the current investigation is that an 8-week aerobic dance program supplemented with a 7% body weight (BW) weighted vest (AD + WV) significantly enhanced upper and lower body muscle strength compared to aerobic dance (AD) alone among older females with low bone mass. While both experimental groups exhibited favorable and comparable cardiovascular adaptations, the lack of significant structural changes in total bone mass and muscle mass suggests that the primary benefits of this shortterm intervention in postmenopausal women may be more functionally and possibly neurologically driven than morphological.

The significant improvement in lower body strength, evidenced by a 38.1% increase in the 30-second chair stand performance in the AD + WV group, suggests a potential benefit of integrating axial loading into dynamic movements. This finding is consistent with that of Srisaphonphusitti and Manimmanakorn [12], who demonstrated that combining a weighted vest with whole-body vibration significantly improved leg muscle strength in community-dwelling older adults. These improvements may hypothetically reflect neuromuscular adaptations, such as enhanced motor unit recruitment or firing frequency, although these mechanisms were not measured directly in the present study and remain speculative. Clinically, under the overload principle, the addition of a 7% BW external load during continuous and multidirectional stepping movements of aerobic dance systematically increased mechanical stress on the antigravity muscles, particularly the gluteal, quadriceps, and hamstring muscles, which may have contributed to these potential neural adaptations [13,14]. In addition to lower extremity enhancements, this investigation revealed a significant improvement in upper body strength, as evidenced by the arm curl test, in the AD + WV group (p = 0.046). Although the weighted vest did not provide direct resistance to the elbow flexors, this improvement could potentially be explained by the biomechanical principle of proximal stability for distal mobility [15]. The application of a 7% BW external load on the torso may systematically challenge the core musculature, particularly the erector spinae and abdominals, to help maintain postural alignment during the continuous and rhythmic arm swings inherent in aerobic dance. This heightened core activation is postulated to create a more stable proximal foundation that could optimize neural drive and force transfer to the upper extremities. However, trunk muscle activation, core stability, and related biomechanical variables were not directly assessed in this study. Consequently, the observed gains in arm strength may represent a potential, though speculative, secondary benefit possibly related to core stability and intermuscular coordination, rather than an evidence-based causal mechanism.

Interestingly, functional strength improved markedly, but the total muscle mass evaluated via body composition analysis remained unchanged. This discrepancy aligns with the findings of Cepeda and Lodovico [16], who showed that an 8-week dance program elicited qualitative changes in muscle architecture (e.g., increased muscle fascicle pennation angle and thickness) in older women rather than gross hypertrophy. Furthermore, significant morphological changes in older adults typically require prolonged and consistent exercise training [5]. Thus, the strength gains observed in our 8-week AD + WV intervention may primarily reflect neural adaptations, including potential motor learning, enhanced intermuscular coordination, and optimized neural drive, rather than quantitative increases in total lean mass. Furthermore, general exercise participation and task familiarization effects across both groups during repeated fitness assessments cannot be ruled out as contributing factors to these functional improvements.

Regarding functional mobility and dynamic balance, evaluated via the Timed Up and Go (TUG) test, the results in this study indicated no significant differences over time or between groups (interaction p = 0.546). This suggests that the addition of a weighted vest did not yield a statistically significant benefit in dynamic balance over the 8-week period compared to aerobic dance alone. Dynamic balance is a complex skill that depends on the integration of the visual, somatosensory, and vestibular systems [17]. The use of a weighted vest disrupts the body’s center of mass (COM) during rhythmic activities, which presents a challenge to postural control. This ongoing disturbance requires proprioceptors in the weight-bearing joints to become more active to maintain stability [18,19]. The fact that the AD + WV group sustained their functional mobility time despite the additional load suggests a potential tolerance to the added weight, without compromising baseline mobility. Our findings align with those of Sanchez-Alcala, Carcelen-Fraile [20], and Li and Wang [21], who emphasized the effectiveness of dance-based interventions in preserving functional capacity. Given the high incidence of fall risk among Thai older adults with low bone mass [1], the safe application of weighted vests without hindering baseline mobility warrants further investigation to clarify its potential utility as a component that may improve physical function associated with fall risk, rather than a direct fall-prevention effect.

From a cardiovascular standpoint, this study demonstrated notable overall decreases in both systolic and diastolic blood pressure over time, without any significant interaction effect between the groups. While the analysis within groups indicated that the AD + WV group experienced a more pronounced statistical reduction in diastolic blood pressure than the AD group, the absence of an overall interaction effect suggests that incorporating the weighted vest did not provide a significantly greater hemodynamic advantage. This finding is reasonable because the weighted vest acts primarily as a mechanical load on the musculoskeletal system rather than directly stressing the cardiovascular system. The marked decrease in blood pressure can be attributed to the aerobic nature of the dance. These findings are consistent with those of Sukjit et al. [4], who reported that continuous rhythmic movements involving large muscle groups enhance endothelial function, decrease arterial stiffness, and improve autonomic regulation, making aerobic dance an effective method for promoting cardiovascular health in older women, irrespective of external loading.

A critical consideration in interventions targeting populations with low bone mass is the impact on bone mineral density (BMD). In the present study, the 8-week intervention was insufficient to elicit detectable changes in total bone mass. While mechanical loading is a well-established stimulus for osteogenesis, bone remodeling in postmenopausal women is a notoriously slow physiological process characterized by an extended time-course. Our findings reflect the observations of Yu, Hsu [22], which highlighted that significant improvements in BMD among postmenopausal women with low bone mass typically require at least 24 weeks of high-impact aerobic dance. Furthermore, a 27-week trial by Greendale, Salem [23] and a 12-month clinical trial by Beavers, Lynch [24] demonstrated that long-term external weight application is necessary to offset structural bone loss, providing a logical explanation for the short-term results in this study. Consequently, while the current shortterm findings demonstrate functional benefits, any potential osteogenic adaptations remain strictly speculative and require verification through long-term trials utilizing DXAbased assessments.

Beyond physiological outcomes, the real-world feasibility and safety of the AD + WV intervention represent critical takeaways. Over the eight-week trial, no participant experienced any training-related injury or musculoskeletal adverse event. For a demographic with low bone mass inherently predisposed to structural damage, this lack of injury is clinically significant. The 7% body weight parameter appears to function as an optimal threshold, potentially contributing to functional adaptation without overloading fragile skeletal structures. Although traditional heavy resistance training remains a highly effective method for building strength, its reliance on specialized gym equipment and constant supervision limits its accessibility. Simply adding a moderately loaded vest to a conventional aerobic routine sidesteps these logistical barriers and offers a highly practical alternative. Despite the practical advantages, caution is warranted. The safety profile established here applies strictly to the 7% load used under supervised conditions; heavier weights or unmonitored home sessions could yield entirely different profiles.

This study has several limitations. First, bone mass parameters were estimated using a bioelectrical impedance analyzer (BIA) rather than the gold-standard dual-energy X-ray absorptiometry (DXA), which may have limited the accurate evaluation of the true bone mineral density or microarchitectural adaptations. Second, exercise intensity was monitored solely via the subjective Borg RPE scale (12-16), lacking objective physiological verification (e.g., continuous heart rate monitoring or indirect calorimetry). This methodological constraint has important implications: the assumption of strict training load equivalence between the two groups cannot be established definitively, as the added axial resistance in the AD + WV group likely imposed higher absolute physiological strain, metabolic demand, and cardiovascular stress. Without concurrent objective measures, it is plausible that group differences in functional outcomes may partly reflect differential training loads rather than differential intervention responses. This limitation underscores the need for objective intensity monitoring in future weighted-exercise studies to comprehensively characterize and equate training doses between experimental conditions. Third, the lack of strict control over dietary intake, specifically calcium and vitamin D consumption, medication use, and daily physical activity outside the prescribed intervention sessions, may have introduced confounding variables. Fourth, the 8-week intervention duration, while potentially sufficient to elicit early functional and neural adaptations, was inherently too brief to yield structural or morphological remodeling in bone or muscle tissues in older adults, thereby contextualizing the lack of significant macroscopic changes in body composition or bone mass parameters. Fifth, although the final sample size (n = 57) in this study satisfied the minimum statistical requirement determined by the a priori power analysis, it may have been underpowered to detect subtle changes in certain non-significant variables (e.g., the TUG test), potentially increasing the risk of a Type II error. Furthermore, multiple statistical comparisons were performed across numerous functional and physiological outcomes without adjusting the alpha level (e.g., Bonferroni correction for all variables). This approach may inflate the risk of a Type I error. Thus, secondary findings with borderline statistical significance should be interpreted with caution. Finally, regarding generalizability and external validity, the study cohort consisted exclusively of community-dwelling postmenopausal women with low bone mass. Therefore, these findings should not be extrapolated to older men, institutionalized populations, or individuals with more severe clinical conditions, such as advanced osteoporosis or sarcopenia, without further verification. To overcome these limitations, future studies should consider an extended intervention period of 6-12 months, incorporating localized DXA scans, biochemical markers of bone turnover, and objective physiological intensity verifications to comprehensively elucidate the longitudinal effects of weighted vest training on bone and muscle remodeling.