Aging With Strength: Functional Training to Support Independence and Quality of Life

Abstract

Functional resistance training (FRT) has been among the most popular fitness trends worldwide for over a decade, driven by its emphasis on movement patterns essential for daily activities and maintaining functional independence. Despite its widespread use, research exploring the impact of FRT on quality of life (QoL) remains sparse and of limited methodological quality, particularly among middle-aged adults (40-60 years old). This review addresses these gaps by synthesizing existing literature on FRT and its effects on muscle strength, movement efficiency, and QoL in this underrepresented demographic. While traditional resistance training builds muscle strength, mass, and endurance, FRT targets functional movement patterns, making it well-suited to sustaining independence during the aging process. By shedding light on the potential of FRT to improve quality of life (QoL) and mobility in middle-aged populations, this review provides actionable insights for healthcare and fitness professionals. Further research is needed to determine long-term outcomes and create evidence-based guidelines for integrating FRT into age-friendly health systems.

Highlights.

● Functional resistance training (FRT) enhances movement efficiency more effectively than traditional resistance training (TRT), with comparable outcomes in terms of strength and muscle mass.

● FRT provides physical benefits that support independence and reduce fall risk, particularly in aging populations.

● Current FRT research is limited, methodologically inconsistent, and often overrepresents female participants.

● Middle-aged adults (ages 40-60) are underrepresented in the literature, limiting age-specific recommendations.

Introduction

Functional resistance training (FRT) has been among the most popular fitness trends worldwide for over a decade, driven by its emphasis on movement patterns essential for daily activities and maintaining functional independence. Functional training, a relatively new training modality that benefits both trained and untrained individuals, has gained popularity in the fitness world and has been used safely and effectively across multiple age groups and populations. ¹ Functional resistance training originated from the desire of the physical therapy community to return patients who had experienced musculoskeletal injuries to total health and to strengthen joints by improving movement patterns to prevent future injuries. ² Functional resistance training utilizes multiplanar and multijoint exercises to foster concurrent adaptations in multiple systems, thereby enhancing movement efficiency.^{2 -4} FRT mimics daily activities, such as standing up or lifting objects, while emphasizing balance, coordination, and movement efficiency in conjunction with muscular adaptations. While resistance exercises demonstrate positive muscular adaptations in strength and endurance, FRT emphasizes balance, coordination, and movement efficiency.^3,5

Functional training has been proposed as an effective alternative to traditional strength training for improving balance and movement patterns.^5,6 Functional training is categorized into movement groups, including squats, lunges, hip hinges, gait, pushing, and pulling.^2,5 Despite its recent evolution as a replacement or adjunct exercise modality to traditional strength training, the stress placed on the body by FRT and its impact on markers of health and fitness require further investigation. As individuals age, FRT may help mitigate the impacts of sarcopenia and reduced mobility, which negatively impact their quality of life. This literature review examines the effects of FRT on health and fitness parameters, demonstrating its efficacy in improving the quality of life (QoL), particularly among middle-aged adults, despite the limited methodological quality of existing research in this population.^7,8

Methodology

This manuscript uses a literature review methodology to assess the current knowledge investigating FRT and its impact on age-related disorders among middle-aged adults. This enables a more comprehensive examination of existing research, identifying gaps and informing future research directions.

A systematic review was impractical due to limited studies on FRT in middle-aged adults and inconsistent study designs. Systematic reviews require a narrow scope and a homogeneous body of evidence, which was absent in this emerging research area. Instead, a narrative literature review allowed for the integration of diverse findings and methodologies to present a more comprehensive picture of the current evidence base.

This review applied explicit inclusion and exclusion criteria to ensure transparency and minimize selection bias. Studies were included if they (1) were peer-reviewed, (2) published in English, (3) focused on functional resistance training (FRT) as an intervention, and (4) reported outcomes related to muscle strength, mobility, balance, fall risk, or quality of life in adult populations, with an emphasis on middle-aged individuals where available. The review’s focus on FRT reassures the reader of its direct relevance to their field. Given the limited research specifically targeting middle-aged adults, studies involving broader adult and aging populations were also considered, as they provided relevant insights. Studies were excluded if they did not focus on FRT or failed to address outcomes linked to functional capacity or quality of life.

Multiple databases were searched to identify potential articles, including PubMed, Google Scholar, and ScienceDirect, using consistent search terms such as “functional resistance training,” “functional training and aging,” “functional training and quality of life,” and “exercise and age-related disorders.” A manual search of key articles’ reference lists was also conducted to ensure comprehensive coverage of the available literature. Articles were organized into thematic categories that are directly aligned with the review’s objectives, including muscle strength and sarcopenia, movement efficiency and fall risk, quality of life, body composition, and cardiovascular parameters.

Functional Training and Quality of Life

Understanding the impact of functional training on middle-aged adults requires first establishing key definitions and context. For this review, functional movement is defined as multi-joint, multi-planar movements that replicate daily locomotor activities. The classification of middle age varies, but for consistency, this review considers individuals aged 40 to 60 as middle-aged, aligning with definitions from the Encyclopedia Britannica Online and the Collins English Dictionary. Maintaining mobility, encompassing locomotion, transfers, and cognitive function, is crucial for preserving functional independence and overall quality of life. Evidence indicates exercise significantly improves health and functional fitness in adults over 40.^9,10 Aging induces structural and physiological changes that negatively impact movement quality, functional capacity, and independence. ³ Sarcopenia, characterized by the loss of muscle mass and strength, typically begins around age 40 and accelerates as aging progresses, ultimately leading to functional decline.^{11 -13} Strength declines by 1 to 2% annually after the age of 50, while muscle mass decreases by approximately 1.5%.^12,13 Guler et al ¹⁴ define functional capacity as an individual’s ability to interact with their environment, typically shown by essential activities such as standing from a seated position, walking, lifting bags of groceries, or reaching for an object on a shelf. Active older adults exhibit significantly better health outcomes than their inactive counterparts. ¹²

Targeted exercise interventions that enhance movement efficiency and motor control have been shown to improve functional capacity. ¹⁵ Resistance training, in particular, mitigates age-related declines in muscle mass and strength, positively influencing movement efficiency. ¹² Beyond musculoskeletal benefits, resistance training is also associated with improved physical function, mental health, cognitive performance, and overall quality of life. ¹⁰ Given the critical role of preserving functional movement efficiency, implementing strategies to counteract muscle loss and strength decline should be a priority in healthcare. This review aims to evaluate the most effective training modality for mitigating these age-related declines while enhancing functional movement capacity.

Comparing FRT and TRT: Effects on Movement Efficiency

Studies comparing FRT and traditional resistance training (TRT) show mixed results. Both improve strength, endurance, and mobility, but FRT may better enhance coordination and functional independence, particularly in those with neuromotor impairments.

Soligon et al ¹³ and de Souza Bezerra et al ¹⁶ found no significant differences between FRT and TRT regarding improvements in muscle mass, strength, and functional movement performance among older adults, indicating that both approaches yield comparable outcomes. Similarly, Kovac et al ¹⁷ reported that incorporating a Functional Movement Screen (FMS)-derived intervention into a traditional strength program did not significantly enhance functional movement scores compared to TRT alone.

However, these studies had key methodological limitations. Soligon et al ¹³ used a relatively short intervention period (≤12 weeks), which may not be sufficient to detect long-term neuromuscular adaptations. de Souza Bezerra et al ¹⁶ focused exclusively on older adults, limiting the applicability of their findings to middle-aged populations. While addressing movement quality, Kovac et al ¹⁷ did not isolate the effects of FRT from the broader training program, making it difficult to determine whether improvements were specifically due to functional training.

In contrast, other studies highlight the unique benefits of FRT in terms of movement quality and functional mobility. For instance, research by Bennett et al ¹⁵ and Beltz et al ¹⁸ revealed that while both FRT and TRT groups experienced similar gains in strength and power, only participants in the FRT groups exhibited significant improvements in FMS scores and core endurance. Interestingly, Beltz et al. noted a decline in movement quality among the TRT group, suggesting that traditional strength training lacking a functional component may decrease movement efficiency over time.

Strand et al ¹⁹ found that while both FRT and TRT improved balance and strength in older adults with Parkinson’s, only FRT reduced Freezing of Gait symptoms. This suggests that FRT’s focus on multi-joint, multiplanar movements may offer neuromotor benefits not typically observed with TRT. Supporting this, Liao et al ²⁰ found that adolescents participating in FRT demonstrated significant improvements in movement efficiency and physical fitness compared to their peers in traditional Physical Education programs.

Underlying Mechanisms and Practical Considerations

The identified differences in movement quality between FRT and TRT can be attributed to biomechanical and neuromuscular variations associated with each training approach. FRT incorporates multi-joint exercises that emphasize the kinetic chain, often including balance and core stability work. In contrast, TRT primarily focuses on isolated, single-plane movements aimed at maximizing hypertrophy and strength gains. ²¹ These fundamental differences may explain why functional bodyweight exercises, such as push-ups, engage the core more effectively than traditional bench press exercises, despite similar primary mover muscle group activation.

However, some studies, including de Souza Bezerra et al, ¹⁶ have found no significant differences in outcomes between single-joint (TRT-like) and compound (FRT-like) exercises. This suggests that FRT’s benefits may not be universally applicable and may depend on various factors, including individual training goals, demographic characteristics, and specific intervention designs. This highlights the need for further investigation to clarify FRT’s role in enhancing movement efficiency, particularly in the context of various populations and study designs. While these studies highlight the role of FRT in improving movement quality, another key consideration is its impact on muscular endurance and movement efficiency compared to TRT. To better understand these effects, the following section examines comparative findings on how each modality influences these attributes.

FRT versus TRT: Impact on Strength and Movement Performance

Several studies indicate no significant differences between FRT and TRT in improving muscle endurance and functional capacity. Zuo et al ²² found that both training protocols produced comparable outcomes in weighted ball throws, vertical jumps, pull-ups, and 30 m sprints among young males, with neither showing a distinct advantage. Similarly, Bennett et al ¹⁵ and Silva et al ²³ reported that both FRT and TRT resulted in similar gains in strength, power, and functional capacity, even in populations with health conditions such as Psoriatic Arthritis.

However, other research suggests that FRT may improve movement efficiency and real-world functional performance more effectively. Liao et al ²⁰ demonstrated that adolescents in an FRT program outperformed their peers in a traditional Physical Education program on both FMS scores and standardized physical fitness tests, suggesting that FRT better translates to overall movement competency. Likewise, Da Silva-Grigoletto et al ² found that FRT led to greater improvements in trunk muscle endurance and rate of force development among older women compared to TRT or a control group.

A particularly interesting finding comes from Cortell-Tormo et al, ²⁴ who reported that participants in an FRT program experienced significant reductions in lower back pain and self-reported disability, as well as improvements in balance, muscular strength, and health-related quality of life (HRQoL). This aligns with the systematic review by Weber et al, ⁷ which concluded that integrating functional exercises into daily routines can enhance motor performance, reduce the risk of falls, and improve long-term movement efficiency in older populations.

Underlying Mechanisms and Practical Considerations

The biomechanical demands of FRT may explain its distinct effects on movement efficiency and functional performance. Unlike TRT, which often emphasizes isolated, single-joint movements, FRT incorporates multi-joint, multiplanar movements, stressing the kinetic chain that also engages stabilizing muscles. Cortell-Tormo et al ²⁴ demonstrated this principle by showing that push-up exercises resulted in significantly greater core activation than traditional bench presses despite similar muscle activation in primary mover muscle groups.

The effectiveness of FRT may also depend on specific training protocols and population characteristics. While some studies, such as those by Zuo et al ²² and Bennett et al, ¹⁵ found no significant differences in functional performance outcomes between FRT and TRT, their study designs focused on short-term interventions (6-12 weeks). In contrast, studies with longer durations (12 weeks or more) and multi-joint movement assessments, such as those by Da Silva-Grigoletto et al ² and Liao et al, ²⁰ have observed greater functional gains with FRT. These variations suggest that intervention duration and exercise selection play a key role in determining the effectiveness of FRT.

FRT Impacts on Balance, Movement Quality, and Fall Risk

Research comparing FRT and traditional TRT suggests that both methods can improve movement quality, although with notable differences. Studies by Bennett et al ¹⁵ and Beltz et al ¹⁸ found that while both training approaches yielded similar increases in muscle strength and power, only the FRT group showed significant improvements in FMS scores. This suggests that FRT may lead to superior gains in movement quality. Additionally, Beltz et al. highlighted a concerning trend: while the FRT group improved, the TRT group actually experienced a decline in movement quality. This raises questions about the efficacy of relying solely on traditional training when prioritizing mobility and movement efficiency.

Building on these findings, Guler et al ¹⁴ investigated a middle-aged population and found that both FRT and TRT improved body composition. However, the FRT group exhibited more significant enhancements in FMS and Balance Error Scoring System (BESS) scores, reinforcing FRT’s advantages in developing balance and movement quality among individuals experiencing age-related decline. These results suggest that FRT may be particularly beneficial for improving functional movement patterns in midlife.

However, Guler et al ¹⁴ had a relatively small sample size (n = 46), which limits the generalizability of their findings. Additionally, while FMS and BESS provide practical, functional assessments, they do not capture all aspects of mobility, such as real-world gait patterns or fall incidence. Future studies should incorporate a broader range of functional movement assessments to provide a more comprehensive evaluation.

Contrasting Evidence and Methodological Considerations

While the evidence favors FRT for balance and movement quality, some studies present conflicting findings. For example, Kovac et al ¹⁷ observed that incorporating an FMS-based intervention into traditional training resulted in a slight improvement in movement scores for female athletes; however, overall functional outcomes remained statistically similar to those achieved through TRT alone. A possible explanation for this outcome is that both groups participated in a standard strength and conditioning program throughout the study period, which may have influenced the FMS scores and confounded the results.

Similarly, de Souza Bezerra et al ¹⁶ found no significant differences in outcomes between groups performing multi-joint exercises characteristic of FRT and those using single-joint exercises. However, the compound exercise group did outperform the single-joint group on specific functional tasks, suggesting that FRT may offer subtle advantages that are not always reflected in traditional strength measures. These findings highlight the need for standardized assessment tools that capture real-world functional improvements rather than relying solely on isolated strength measurements.

FRT and Fall Risk Reduction

Evidence supports the use of FRT for reducing fall risk. Josephson and Williams ²⁵ found that FRT improved balance and reduced falls more than TRT or control groups. These findings align with those of Guler et al ¹⁴ and Cortell-Tormo et al, ²⁴ whose results demonstrated enhanced balance improvements with FRT.

However, not all studies support this conclusion. Thulher do Rosario et al ²⁶ reported no significant improvements in fall risk or functional tests after a combined FRT and stretching program. One potential explanation is that including a stretching component diluted the effects of FRT, leading to less pronounced improvements. This highlights the importance of program design in maximizing the benefits of functional training.

In summary, while both FRT and TRT contribute to strength gains, FRT presents distinct advantages for balance, movement efficiency, and fall risk reduction - particularly critical factors for health-related quality of life (HRQoL) in aging populations. However, the lack of research on middle-aged adults raises important questions about whether these benefits extend to this demographic at a stage when preventive measures may be most effective. Future studies should examine whether integrating FRT during middle age can help delay or attenuate fall risk and mobility loss in later years.

Functional Exercise and Physical Characteristics

Muscle Mass and Strength: Synthesis of Findings

Studies consistently indicate that FRT and TRT are effective methods for increasing muscle mass and strength. However, FRT presents unique advantages in secondary outcomes, such as pain reduction, enhanced movement efficiency, and lower perceived exertion - factors that may result in improved exercise adherence and long-term engagement.

For example, Soligon et al ¹³ and Strand et al ¹⁹ reported comparable strength gains between FRT and TRT. Notably, Strand et al. found that FRT improved muscle strength while also alleviating Freezing of Gait symptoms in patients with Parkinson’s disease and enhancing balance and functional capacity. This suggests that FRT may offer additional neuromotor benefits beyond strength alone. Similarly, Mile et al. ¹¹ demonstrated that a 6-month FRT program significantly attenuated the severity of sarcopenia in older adults. However, the study’s focus on clinical populations limits its applicability to middle-aged adults at an earlier stage of functional decline.

Bennett et al ¹⁵ further support the advantages of FRT, reporting that while both FRT and TRT improved strength and movement quality, the FRT group experienced a 27% reduction in reported perceived exertion. This could encourage long-term participation. However, the study did not track adherence beyond the intervention period, making it unclear whether this benefit translates to sustained exercise habits. Additionally, as the study primarily included young adults, its relevance to middle-aged individuals remains uncertain. Future research should investigate whether FRT’s lower perceived exertion rates promote long-term adherence, particularly among populations at risk for functional decline.

While Cassemiro et al ²⁷ found no significant differences in strength gains between FRT and TRT among young women, the FRT group reported fewer musculoskeletal complaints. This suggests that even when strength outcomes are comparable, FRT may reduce training-related discomfort, potentially improving long-term adherence among specific populations.

Despite these promising findings, considerable gaps still exist in the current research. Middle-aged adults - a critical demographic for early intervention against functional decline - are noticeably underrepresented. Most studies focus on younger or older populations, leaving an important gap in understanding FRT’s role in this critical age bracket. Additionally, the short duration of most interventions (typically 8-12 weeks) limits our ability to assess the long-term impact of FRT on muscle strength, mobility, and quality of life (QoL).

FRT and Body Composition: Evaluating Its Effectiveness

Research on the impact of FRT on body composition has yielded mixed results, with several studies indicating limited changes in fat mass, fat-free mass, and body mass index (BMI). However, variations in methodology, training intensity, and participant demographics provide insights into the potential role of FRT in a broader health application lens.

FRT and Body Composition: Inconsistent Findings

Multiple studies suggest that FRT alone may not significantly alter body composition metrics. Stavres et al ²⁸ examined the effects of an FRT program on middle-aged women (48 ± 5 years) and found that while the basal metabolic rate increased, there were no notable changes in fat mass, fat-free mass, or BMI. The study’s limitations, including its single-group, non-randomized design, weaken the strength of its conclusions, raising questions about the efficacy of FRT for weight management.

Similarly, La Scala Teixeira et al ²⁹ conducted a rigorous randomized controlled trial (RCT) on women aged 30 to 50, comparing an FRT-only group to an interdisciplinary group that combined FRT with endurance training. The FRT-only group showed improvements in cardiorespiratory fitness but did not experience significant changes in BMI or body fat. In contrast, the interdisciplinary group saw positive changes in these areas, reinforcing the idea that FRT may be most effective when integrated with endurance training and nutritional guidance.

Findings from older adult populations further support this trend. Ponce-Bravo et al ³⁰ examined FRT versus recreational activities in 70-year-olds and found that both groups improved in strength and aerobic capacity, though neither group exhibited significant changes in body composition. However, only the FRT group demonstrated statistically significant improvements in handgrip strength, gross motor abilities, and cognitive performance, suggesting that while FRT enhances functional fitness, its effects on body composition remain unclear.

Artese et al ³¹ further support the lack of changes in body composition following FRT interventions. They examined breast cancer survivors (mean age 60.3 ± 8.3 years) undergoing either a 24-week FRT plus high-impact exercise program or a yin yoga intervention. Neither group showed significant changes in body composition, bone mineral density, or biomarkers for bone metabolism. However, both groups improved lower-body strength, with the FRT group also gaining upper-body strength.

One possible explanation for these findings is the relatively low training intensity in the FRT program. Previous research suggests that higher-intensity resistance training may be required to elicit meaningful changes in body composition. Additionally, breast cancer survivors face unique physiological challenges that may influence their training responses. Future studies should investigate whether higher-intensity FRT protocols can yield more significant improvements in body composition, particularly in middle-aged, healthy populations.

Intensity and Frequency: A Potential Factor

While many studies focus on moderate-intensity FRT protocols, emerging evidence suggests that higher-intensity functional training may yield different results. Smith et al ³² investigated the effects of high-intensity functional training (HIFT) performed at different frequencies (1-3 times per week) over 12 weeks. Regardless of training frequency, all training groups showed improvements in cardiometabolic markers, metabolic syndrome severity score (MSSS), and perceived fitness levels. Interestingly, the group that met twice a week exhibited the most pronounced improvement in MSSS, achieving a clinically significant result. The study also reported high exercise enjoyment and adherence levels across all frequency groups, suggesting that training intensity and adherence may influence the effectiveness of FRT. However, the study’s small sample size (n = 4, n = 8, and n = 9, respectively) limits the generalizability of these findings.

These findings highlight several key points regarding FRT’s role in body composition changes. Across different populations, studies consistently indicate that FRT alone does not significantly alter fat mass, fat-free mass, or BMI. However, research by La Scala Teixeira et al ²⁹ suggests that combining FRT with endurance training and nutritional guidance may be necessary for meaningful body composition changes. Additionally, training intensity may be a critical factor, as studies by Artese et al ³¹ and Smith et al ³² suggest that low-intensity protocols may not be sufficient to drive changes. In contrast, higher-intensity training may offer more substantial metabolic benefits. Another important consideration is adherence; as Smith et al ³² point out, the high levels of exercise enjoyment reported in FRT programs could play a crucial role in sustaining long-term engagement and health improvements.

While FRT provides notable benefits for strength, movement quality, and functional performance, its role in modifying body composition remains questionable. Future research should explore how training intensity, frequency, and training program duration influence body composition outcomes, particularly in middle-aged and older adults.

Comparative Analysis of FRT versus TRT Training Outcomes

Studies comparing FRT and traditional resistance training TRT have produced mixed results, with some showing comparable outcomes and others highlighting distinct advantages of FRT. Zuo et al ²² examined the impact of FRT and TRT on muscular endurance and physical performance in young males (22.1 ± 2.9 years), using measures such as weighted ball throws, vertical jumps, pull-ups, and 30 m sprints. The results indicated no significant differences between the groups across any category. However, an important limitation of this study was that it did not assess balance, a key area where FRT is often hypothesized to provide additional benefits. Additionally, the FRT group used low-intensity exercises on unstable surfaces (eg, balance board, bosu ball), which may have influenced the findings. Future research should investigate whether higher-intensity FRT protocols yield different results, particularly in terms of movement efficiency and neuromuscular control. However, using unstable platforms necessitates employing reduced-intensity protocols.

In contrast, Liao et al ²⁰ found that a 12-week FRT program significantly improved movement efficiency and physical performance in adolescents compared to those in a standard physical education curriculum. Participants in the FRT group demonstrated more significant gains in movement competency, as measured by the Functional Movement Screen, and achieved higher scores on a standardized physical fitness test. These findings suggest that FRT may be particularly beneficial for improving movement quality in younger populations, though further investigation is needed to determine whether similar benefits extend to adults.

Da Silva-Grigoletto et al ² provided further evidence of FRT’s efficacy in older populations, comparing FRT and TRT in women aged 65 to 66 years. Their findings indicated that while both training modalities improved strength and endurance, FRT led to greater muscular adaptations in the trunk muscles and a higher rate of force development. These results align with studies suggesting that FRT’s multi-joint, multi-planar movements may enhance neuromuscular function beyond traditional resistance training.

However, not all studies support a clear advantage for FRT. Bennett et al ¹⁵ compared an 8-week FRT program to TRT and found no significant differences in movement quality or physical performance. Both groups experienced similar improvements in muscular power and strength. Interestingly, the FRT group reported consistently lower perceived exertion, a factor that may positively influence exercise adherence and long-term engagement. Despite this, the study did not track adherence beyond the intervention period, limiting conclusions about whether lower perceived exertion translates to sustained participation.

Further complicating the comparison, Silva et al ²³ investigated the effects of FRT versus TRT in middle-aged adults with Psoriatic Arthritis using a 12-week, twice-per-week protocol. Both groups experienced similar improvements in functional capacity, muscular strength, and overall quality of life (QoL). However, the FRT group reported significantly higher improvements in the social domain of QoL, suggesting that FRT may offer additional psychological or social benefits that warrant further exploration.

Broader Implications of FRT in Health and Quality of Life

Beyond traditional performance measures, FRT has been linked to broader health benefits. Cortell-Tormo et al ²⁴ found that FRT improved balance, fitness, and HRQoL. The study, conducted on women from a physical therapy clinic, supports the idea that FRT may be particularly effective in pain management and rehabilitation settings.

A systematic review by Weber et al ⁷ further examined the integration of functional training into daily life among adults over 60. Their findings suggest that FRT can enhance motor performance, balance, and strength while reducing the risk of falls, making it a valuable component of age-focused exercise programs. However, the long-term feasibility of integrating FRT into routine exercise remains underexplored.

FRT and Cardiovascular Health: A Review of Its Effects

Research suggests that FRT has an equivocal impact on cardiovascular parameters, as evidenced by the meta-analysis performed by Da Costa de Rezende Barbosa et al. ⁵ Da Costa de Rezende Barbosa et al. investigated the effects of functional exercise on cardiorespiratory health. Da Costa de Rezende Barbosa et al. evaluated studies that included the effects of FRT on cardiorespiratory measures (heart rate, blood pressure, double product, oxygen saturation, respiratory rate, and heart rate variability), balance, coordination, and core exercises compared to other types of exercise interventions or a control group. Da Costa de Rezende Barbosa et al. found ambiguous results, indicating that FRT is no better or worse than other interventions in terms of cardiorespiratory measures. The authors cited poor evidence quality on the topic and recommended further studies to clarify the effects of FRT on the cardiovascular and respiratory systems. The inconsistency in findings may be attributed to variations in study designs. Some trials included low-intensity functional exercises, which may not provide sufficient stimulus for cardiovascular adaptations. Others lacked control groups, making it difficult to isolate the effects of FRT. Future research should focus on well-controlled, high-intensity FRT interventions to determine their actual impact on cardiovascular health.

Functional Training and the Cardiovascular System

Research examining the effects of FRT on cardiovascular health presents equivocal findings. A key area of agreement is the positive influence of FRT on autonomic modulation, with multiple studies indicating improved heart rate variability (HRV) and reduced resting heart rate. For instance, Turri-Silva et al ³³ found that FRT led to greater reductions in systolic and diastolic blood pressure compared to TRT. Similarly, De Rezende Barbosa et al^5,34 demonstrated that FRT enhances parasympathetic activity and HRV in both young and menopausal women, reinforcing its potential role in cardiovascular regulation.

However, discrepancies emerge regarding the magnitude and consistency of these effects across populations. While Lima et al ⁶ reported improvements in post-exercise hypotension in both young and older adults, the study’s small sample size limits generalizability. Additionally, while do Nascimento et al ³⁵ found that FRT and TRT yielded comparable improvements in peak O2, QoL, and functionality among heart failure patients, adherence rates below 80% introduce uncertainty about long-term efficacy. These findings highlight the need for more rigorous, large-scale studies to confirm FRT’s cardiovascular benefits across diverse populations.

Gaps in Research and Methodological Considerations

A critical gap in the literature is the limited exploration of long-term adherence and sustainability of FRT interventions. Most studies focus on short-term physiological outcomes, leaving questions about whether the observed cardiovascular benefits persist over extended periods. Furthermore, participant demographics vary significantly across studies, with some focusing on young, healthy individuals ³⁴ while others examine clinical populations such as those with metabolic syndrome or heart failure.^33,35 The lack of standardized protocols regarding FRT intensity, duration, and exercise selection further complicates direct comparisons and highlights the need for greater methodological consistency in future research.

Implications for Practice and Future Research

The overall findings suggest that FRT may be a viable strategy for improving autonomic function and cardiovascular health, particularly in populations with existing cardiovascular risk factors. However, practitioners should be mindful of individual variability in response to training and consider monitoring long-term adherence to maximize benefits. Future research should prioritize longitudinal studies that assess the sustainability of FRT-induced cardiovascular adaptations and investigate the role of various training variables (eg, session length, frequency, and intensity) in optimizing outcomes. Exploring psychological and behavioral factors influencing adherence could provide valuable insights for developing more effective exercise interventions.

The Mind and Functional Training

Adherence is a critical factor in the effectiveness of any exercise program, as the benefits of physical activity can only be realized through consistent participation. Research suggests that functional training may promote long-term adherence by fostering positive psychological outcomes. Smith et al ³² found that individuals participating in high-intensity functional training (HIFT) reported high levels of enjoyment regardless of training frequency, suggesting that FRT may encourage sustained engagement in physical activity. Similarly, Faro et al ³⁶ compared the psychological effects of FRT and TRT in a sample of 34 females and found that both modalities improved mood and reduced state anxiety, but FRT resulted in a significantly greater reduction in anxiety levels. Interestingly, despite similar ratings of perceived exertion, FRT resulted in a higher mean percentage of age-predicted maximum heart rate, indicating a potentially greater physiological demand.

In addition to short-term psychological benefits, functional training may also yield long-term improvements in mental well-being. Laredo-Aguilera et al ³⁷ conducted a 10-week intervention with older adults and found that functional training significantly enhanced mood quality, reduced depression, improved sleep quality, and mitigated fatigue. These findings align with those of Faro et al, ³⁶ reinforcing the notion that FRT can serve as a potent tool for enhancing emotional well-being across different populations. However, while Faro et al. examined acute effects in a younger population, Laredo-Aguilera et al. focused on long-term outcomes in older adults, highlighting a gap in research on the sustained psychological effects of FRT in younger demographics.

An emerging area of interest is the potential cognitive benefits of functional training. de Almeida et al. ³⁸ examined the acute impact of FRT versus TRT on executive function in obese older adults, using measures such as the Stroop Test and the Trail Marking Test. Both training modalities yielded improvements, suggesting that resistance training, in general, may enhance cognitive function. However, the study’s small sample size (FRT group, n = 15; TRT group, n = 16) and the lack of a long-term follow-up limit the generalizability of these findings. Similarly, Ballester-Ferrer et al ³⁹ investigated the cognitive effects of HIFT in college students, finding that in-person training significantly improved processing speed. However, when the intervention shifted to an online format due to the COVID-19 pandemic, these gains were no longer observed, and adherence declined. This highlights a key limitation: while functional training may confer cognitive benefits, external factors such as training modality and social engagement may influence outcomes.

Collectively, these findings indicate that functional training has the potential to enhance both psychological well-being and cognitive function. However, gaps remain in the literature, particularly regarding long-term adherence and the differential effects of FRT across various age groups and training environments. Future research should explore the mechanisms underlying these benefits and assess the sustainability of cognitive and psychological improvements over extended periods.

Conclusion: Research Gaps and Future Directions for FRT

While FRT is routinely shown to enhance balance and functional movement, its comparative efficacy to TRT remains mixed. Some studies, such as those by Soligon et al ¹³ and Strand et al, ¹⁹ report similar improvements in muscle strength and functional capacity between FRT and TRT. Others, including Bennett et al ¹⁵ and Beltz et al, ¹⁸ highlight FRT’s unique benefits in improving movement efficiency and reducing perceived exertion - factors that may support better long-term adherence.

Despite these promising outcomes, significant research gaps remain. First, middle-aged adults (40-60 years) - a key demographic at risk for sarcopenia and functional decline - are underrepresented in current studies, which predominantly focus on older adults or athletes. Second, there is a lack of gender diversity, as many studies disproportionately include female participants, limiting generalizability to males and mixed-gender populations. Third, most interventions are short-term (8-12 weeks), providing limited insight into the long-term effects of FRT on muscle health, movement efficiency, and quality of life (QoL).

While studies like Beltz et al ¹⁸ demonstrate strong methodological approaches, including functional movement assessments and adherence tracking, others (eg, Liao et al ²⁰ ) face issues with generalizability due to homogeneous samples and short follow-up periods. Future research should adopt standardized protocols, include more diverse participant groups, and extend the duration to fully understand FRT’s potential.

To address these gaps, future research should prioritize:

1. Long-Term Effects: Conduct longitudinal studies on muscle strength, movement efficiency, and QoL in middle-aged adults.

2. Tailored Interventions: Develop FRT programs optimized for middle-aged adults, focusing on frequency, intensity, and adherence.

3. Comparative Studies: Utilize standardized outcomes in randomized controlled trials (RCTs) to compare FRT and TRT.

4. Diverse and Gender-Inclusive Samples: To improve generalizability, include participants of varied genders, backgrounds, and health statuses.

5. Practical Integration: Explore real-world applications, such as community programs, workplace wellness initiatives, and telehealth platforms, supported by wearable technology for monitoring and personalization.

For practitioners, FRT presents a promising alternative to traditional resistance training, particularly for those seeking to enhance balance and functional independence. As research advances, incorporating FRT into accessible health initiatives may offer a scalable approach to maintaining functional capacity across the lifespan, particularly in underrepresented middle-aged populations.

Study Characteristics Summary Table.

Study (Author, Year)	Sample Size & Population	Methodology	Key Findings	Limitations
Bennett et al., 2019	Trained adults (n = 46)	RCT, FRT vs TRT	Both groups improved strength and movement quality; FRT showed lower perceived exertion	Small sample, short duration (8 weeks)
Beltz et al., 2019	24 young adults (20.6 ± 1.1 years)	RCT, 12-week FRT vs TRT	FRT improved movement quality and core endurance; TRT declined in FMS scores	University students only, limiting generalizability
Soligan et al., 2020	42 older adults	Suspension-based FRT vs TRT	Comparable improvements in strength and function	Did not show superiority of FRT, used body weight suspension training
Cortell-Tormo et al., 2018	24 adult women (25-45 years)	FRT intervention vs control	Improved QoL, pain reduction, increased strength and balance	Small sample, women-only
Josephson & Williams, 2017	Older adults (>65 years) (n = 15 women/n = 3 men)	FRT vs TRT vs control	FRT reduced fall risk and improved balance; TRT and control showed no improvement	Age-limited population
Guler et al., 2021	46 middle-aged adults FRT n = 26, TRT n = 20	FRT vs TRT	FRT improved balance (BESS) and functional movement (FMS)	Short duration, limited diversity
Mile et al., 2021	Older adults with sarcopenia n = 35	6-month FRT	Improved muscle mass, reduced severity of sarcopenia	Medication use (ACE inhibitors) may confound results
Strand et al., 2021	Older adults with Parkinson’s Disease (n = 35)	Strength/power/hypertrophy vs strength/power/FRT	Both improved balance/strength; FRT improved Freezing of Gait	Specific to Parkinson’s, limits generalizability
Aragao-Santos et al., 2021	postmenopausal women (n = 108)	FRT vs concurrent training	Both improved function; FRT improved quicker	No immune function changes despite hypothesis
Stavers et al., 2018	Middle-aged women (48 ± 5 years)	FRT single-group trial	Increased basal metabolic rate, no change in body mass or fat	Non-randomized, small sample
Weber et al. (2017)	Systematic review (Older adults, n varies across studies)	Review of FRT interventions on motor performance, balance, and strength	FRT enhances motor performance, balance, and reduces fall risk	Poor evidence quality, heterogeneous methodologies
Da Costa de Rezende Barbosa et al. (2018)	Meta-analysis (Multiple studies, varying populations)s	Evaluated FRT effects on cardiovascular parameters	Mixed results; FRT had no clear advantage over other interventions for cardiovascular health	Limited high-quality trials, inconsistent methodologies

Legend: Functional Resistance Training; TRT = traditional resistance training; RCT = randomized controlled trial; FMS = functional movement screen; BESS = balance error scoring system; QoL = quality of life.