Heart Rate Monitoring in Unified Basketball: Applications and Relevance for Athletes with Intellectual Disabilities

Abstract

The aim of this pilot study is to explore the applications and relevance of heart rate (HR) monitoring in unified basketball during training and competition circumstances, focusing on athletes with intellectual disabilities. Six UB national team athletes were monitored using Polar Verity Sense heart rate monitors throughout training sessions and competitions. The data revealed considerable individual variability in HR responses among the athletes. These variations highlight the importance of personalized HR monitoring to accurately assess training loads and optimize performance. However, when applying HR monitoring, it is essential to account for factors that may affect data accuracy, including consistency in device placement and environmental stressors such as competition anxiety. Additionally, athletes with cardiovascular comorbidities may display atypical HR patterns, requiring cautious interpretation of HR thresholds. Although the small sample size limits the broader applicability of the findings, this study explores the application and relevance of HR monitoring, highlighting the need for future research to further validate its effectiveness.

1. Introduction

Engagement in sports provides individuals with a deep sense of belonging and opportunities to develop new skills [1]. Organized sports offer not only structured activities with essential physical and psychological benefits but also a secure environment where individuals, particularly youth, can thrive while their caregivers are occupied. However, modern lifestyles, characterized by prolonged “screen time” activities such as television, gaming, and electronic communication, have led to a concerning decline in physical activity levels among young people [2]. Individuals with intellectual disabilities face multiple barriers that limit their participation in physical activity. These barriers can be categorized into personal, social, environmental, financial, and organizational factors. Personal barriers include low self-confidence in physical abilities (perceived capability) [3,4], health-related issues such as mobility impairments [5,6,7], and a preference for sedentary activities [8], which reduces motivation for exercise. Social barriers involve a lack of encouragement and support from family, friends, and caregivers, which is essential for motivation [3,4,9]. Additionally, caregivers’ time constraints, limited resources, and negative societal attitudes further restrict opportunities for engagement [9,10]. Environmental barriers include inaccessible facilities and transportation challenges, as many individuals with intellectual disabilities depend on others to reach activity venues [4,5]. Furthermore, there is a lack of tailored programs specifically designed to meet their needs, leading to limited participation opportunities [5,6,10]. Financial barriers stem from the high costs associated with fitness programs, specialized equipment, and transportation, which are often unaffordable without external financial support [3,7]. Limited funding for inclusive programs further exacerbates this issue. Organizational barriers include a shortage of trained staff who can effectively support individuals with intellectual disabilities and poorly structured programs that do not incorporate family involvement or provide individualized support [3,4,9]. Addressing these barriers requires a comprehensive approach, focusing on enhancing social support, improving accessibility, providing financial assistance, and developing inclusive, tailored programs.

Inclusive sports programs, like Special Olympics Unified Sports^®, have become powerful tools in fostering greater understanding, acceptance, and integration of individuals with intellectual disabilities into society. By bringing together athletes with and without intellectual disabilities on the same teams, these programs create spaces where meaningful social interactions naturally occur. Through shared experiences in training, competition, and social events, participants build connections that challenge stereotypes and reshape perceptions of intellectual disability [11,12,13].

One of the most significant impacts of these programs is the improvement in attitudes toward individuals with intellectual disabilities. When people without disabilities engage directly with their peers who have intellectual disabilities, they begin to see beyond the label. They recognize the skills, determination, and unique personalities of their teammates. This exposure helps break down preconceived notions, fostering empathy and acceptance. Research has consistently shown that both teammates and volunteers involved in inclusive sports develop more positive attitudes compared with those who have little or no contact with individuals with intellectual disabilities [11,14].

Inclusive sports also play a vital role in enhancing social inclusion [15]. For many individuals with intellectual disabilities, opportunities to engage in social activities with peers can be limited due to societal barriers and misconceptions [16]. Inclusive sports programs provide a platform for these individuals to connect with others in a supportive and equal environment. The friendships and bonds formed through these programs extend beyond the playing field, helping to integrate individuals with intellectual disabilities into the broader community and promoting a sense of belonging [17,18].

In addition to fostering social connections, these programs open up new opportunities for participation [12,19]. Athletes with intellectual disabilities are introduced to a variety of sporting events and social activities, allowing them to showcase their talents and actively engage in community life. Programs like the Special Olympics not only highlight the abilities of these athletes but also empower them by providing spaces where their achievements are recognized and celebrated.

Moreover, inclusive sports contribute significantly to physical and motor skill development. Participants often experience improvements in fitness levels, coordination, and sport-specific skills [20,21]. The first review study also confirms that training programs, including Special Olympics (SO) and unified sports (UNS), have been shown to enhance fitness, motor performance, and behavioral outcomes in individuals with intellectual disabilities, while also significantly increasing muscle strength and improving body composition in those with Down syndrome [22]. These physical benefits not only enhance their performance in sports but also contribute to overall health and well-being. The confidence gained from developing these skills further encourages continued participation, both in inclusive sports and in other physical activities. The success of inclusive sports programs heavily relies on the vision and commitment of coaches. Training programs for coaches are essential to equip them with the necessary skills and knowledge to support athletes with intellectual disabilities effectively [23,24]. While inclusive sports programs have shown positive outcomes, ongoing efforts are needed to maintain and enhance these benefits. This includes continuous research to identify best practices and address any barriers to inclusion [17,25].

Special Olympics (SO) programs for youth with intellectual disabilities are growing rapidly and dynamically worldwide. One of the youngest, innovative and rapidly expanding global models is Unified Sports^® (US). This provides equitable inclusion in the training and competition settings of athletes (persons with intellectual disabilities) and sport partners (persons without intellectual disabilities). Unified Sports^® offer young people with intellectual disabilities the opportunity to be engaged more quickly in a particular sport, support their limited social lives and encourage interaction with their peers. The primary goal of the SO is to actively encourage youth with intellectual disabilities to participate in sports activities.

Unified Sports^® emerged in the early 1990s as a collaborative effort between the Special Olympics and the International Olympic Committee. The goal was to create a more inclusive and accessible sports environment for individuals with intellectual disabilities. The first Unified Sports^® competitions were held in the United States and Canada in 1992. In 1995, Unified Sports^® became a global initiative that expanded to countries worldwide. In 2000, Unified Sports^® was officially recognized as a core Special Olympics program. From 2015 until today, the Unified Sports^® movement has continued to grow, with over 1 million athletes participating worldwide. Special Olympics Unified Sports^® includes three inclusive sports models that involve individuals with and without intellectual disabilities [26].

Among the various Unified Sports^®, basketball is particularly significant for its emphasis on teamwork and its dynamic, high-intensity nature. However, research on the physiological demands of unified basketball, particularly heart rate (HR) responses, remains limited. Determining an accurate average HR for athletes in unified basketball can be challenging due to several factors. First and foremost is individual variation. HR varies significantly from individual to individual based on factors such as age, fitness level, and general health. The second is experience in the live sport. More experienced players may be able to maintain lower HR during the same level of play due to improved fitness and technique. The third is playing position. Players in different positions may experience different levels of physical exertion, which can affect their HR. For example, playmakers usually do more running and quick movements because they work more with the ball than other players. Last but not least is the intensity of the game. A basketball game’s intensity can vary, affecting the heart rate. A more competitive or fast-paced game will likely result in higher HR than a more relaxed or slower game.

That being said, studies on traditional basketball have shown that average heart rates during a game can range from 170 to 190+ beats per minute during training and game play [27]. While unified basketball may have some variations due to the inclusion of athletes with intellectual disabilities, these values may serve as a foundational reference.

1.1. Applications of Heart Rate Monitoring in Unified Basketball

Measuring players’ heart rates in basketball has several applications that can be used in unified basketball. These can be categorized as (a) monitoring exercise intensity; (b) assessing players’ fatigue status; and (c) quantifying intrinsic training load using established models [27].

1.2. Monitoring Exercise Intensity

In unified basketball, a 5×5 format closely mirrors standard basketball’s intensity and physical demands. Teams consist of six athletes (players with intellectual disabilities) and four sport partners (players without intellectual disabilities). The selection of unified basketball teams emphasizes equal opportunities for both athletes and sports partners, ensuring a balanced intensity level during gameplay. This approach also considers the physical and functional readiness of the entire team.

Given that athletes with intellectual disabilities often experience comorbid cardiovascular conditions, monitoring their physiological condition during training is essential. The intermittent nature of basketball’s game load, places diverse physical demands on players, requiring coaches to have an in-depth understanding of their team members’ overall and momentary fitness levels. Implementing heart rate (HR) monitoring during training enables coaches to control and adjust workload based on individual capabilities. They will have the possibility to track players’ responses to physical exertion and fine-tune training intensity to help athletes reach the higher functional thresholds essential for competitive matches.

HR monitoring provides coaches insights into player-specific endurance and tactical adherence under high-intensity conditions during games. It may allow coaches to evaluate each athlete’s capacity to follow the current applied strategy, handle a suspension of play or substitutions, execute free throws, and recover their personal fitness during the match. These insights are critical for optimizing team strategies, ensuring safety, and enhancing the performance of all players, particularly athletes with intellectual disabilities.

1.3. Assessing Players’ Fatigue Status

The measurement of player HR can provide insight into their state of fatigue in response to a single dose or repetitive bouts of exercise. Heart rate recovery responses are an established marker for determining cardiovascular adaptations to exercise [28]. An athlete who exhibits significant differences in heart rate (HR) between training sessions (lower values) and competitive matches (higher values) may be experiencing poorly adjusted functional preparation. This discrepancy suggests that the training load has not been appropriately matched to the athlete’s competitive demands. Regardless of skill level, fatigue in unified basketball players can lead to technical errors during gameplay or increase the risk of injury.

On the other hand, athletes with lower HR values during games may demonstrate successful physiological adaptation to training. However, this can also indicate a limited understanding of the competitive aspects of unified basketball, potentially resulting in under-engagement during high-pressure situations. Coaches must carefully analyze HR data to identify these patterns and adjust training and gameplay strategies.

1.4. Quantifying Internal Training Load

Currently, there is a lack of data on heart rate (HR) monitoring for athletes in unified basketball during both training sessions and official/competitive matches. Observing HR during training could allow coaches to determine each athlete’s individual average working heart rate and maximum HR thresholds under consistent load conditions. This approach enables the customization of internal training loads tailored to each athlete’s functional capabilities, ensuring they receive appropriate physical challenges. Such monitoring may help optimize their preparation and recovery, laying the foundation for peak performance in official competitions.

Up to the present time, HR-based training load models have predominantly been the most popular approach to monitor the internal loads experienced by basketball players [29,30,31,32,33].

1.5. Aims and Objectives of the Study

Although heart rate (HR) monitoring is widely utilized in sports, the current literature on unified sports, particularly unified basketball, lacks a comprehensive review that outlines HR measurement’s primary applications and limitations. Furthermore, there is a lack of research addressing the typical training and game-specific HR responses among athletes with intellectual disabilities. Therefore, this pilot study aims to explore the applications and relevance of heart rate (HR) monitoring in unified basketball during training and competition circumstances, focusing on athletes with intellectual disabilities. Given the limited sample size of participants, the study objectives have been tailored to emphasize individualized insights and exploratory findings:

(a)

To explore the practical applications of HR monitoring with group of athletes with intellectual disabilities training in unified basketball, to track exercise intensity, to manage fatigue, and to optimize performance.

(b)

To identify individual variability and physiological limitations in HR responses among unified basketball athletes with intellectual disabilities, considering factors such as fitness levels, health conditions, and game-specific demands.

(c)

To analyze and compare HR responses during training sessions and games, providing insights into the physiological demands of unified basketball for athletes with intellectual disabilities.

(d)

To explore HR monitoring as a potential method for providing objective feedback on training load and exertion levels, especially for athletes with intellectual disabilities who may face challenges in giving verbal or reliable responses about their current physical state.

(e)

To assess the feasibility of HR monitoring models for use in unified basketball, emphasizing their applicability to individualized training needs.

(f)

To propose preliminary insights for unified basketball coaches and sport professionals on the potential integration of HR monitoring practices, highlighting its relevance for enhancing safety, inclusivity, and performance, and addressing the specific needs of athletes with intellectual disabilities.

2. Materials and Methods

The participants in this pilot study were six athletes with intellectual disabilities. They were officially registered as athletes with intellectual disabilities under the Special Olympics basketball program. They were verified through the Special Olympics eligibility process, which explicitly requires that athletes meet the criteria for intellectual disabilities as defined by the Special Olympics General Rules, Section 2.01(d) [34].

All six athletes in this study, as listed in

Table 1. Medical diagnoses, functional limitations and comorbidities of study participants.

No.	Athlete	Medical Diagnosis	Functional Limitations (General Learning and Adaptive Skills)	Eligibility for SO as Intellectual Disabilities International Competitions (SO)	Cardiovascular Comorbidities
1	A 1	ADHD (F90.1)	Difficulty with sustained attention, impulsivity, and poor self-regulation (affecting learning and social skills), limited independent living skills	Confirmed intellectual disabilities FIBA Open European Games 3 × 3, SO European Unified Basketball Championship, Special Olympics World Games 2023	Bradycardia
2	A 2	Childhood Autism (F84.0)	Social communication difficulties, repetitive behaviors, and limited adaptive skills (self-care and social interaction), limited independent living skills	Confirmed intellectual disabilities Participation at national level	None
3	A 3	Moderate intellectual disability (F71)	Limited cognitive processing, poor problem-solving, difficulty with academic tasks, and limited independent living skills	Confirmed intellectual disabilities Participation at national level	Supravalvular aortic stenosis
4	A 4	Dyslexia (R48. 0)	Significant difficulty with reading, hand writing, and mathematical skills; reduced ability to understand complex instructions, impulsivity, poor self-regulation and limited independent living skills	Confirmed intellectual disabilities FIBA Open European Games 3 × 3, SO European Unified Basketball Championship, Special Olympics World Games 2023	None
5	A 5	Williams–Beuren syndrome (Q93. 82)	Delayed cognitive development, social anxiety, poor spatial awareness, and difficulty with self-care skills, limited independent living and working skills	Confirmed intellectual disabilities FIBA Open European Games 3 × 3, SO European Unified Basketball Championship, Special Olympics World Games 2023	Tetralogy of Fallot—corrected by surgery
6	A 6	ASD (F84.0)	Impaired social communication, repetitive behaviors, difficulty with adaptive functioning (self-care, decision-making), limited independent living skills	Confirmed intellectual disabilities Participation at national level	None

with their primary diagnoses, were confirmed to have functional limitations in both general learning and adaptive skills, meeting the eligibility criteria for participation in the Special Olympics.

Three of the athletes (athletes 1, 4 and 5) were not only recognized as having intellectual disabilities through this process but also successfully participated in major international competitions that require compliance with these criteria (Table 1). Specifically, they competed at the following events: the FIBA Open European Games 3 × 3; the SO European Unified Basketball Championship in Druskininkai, Lithuania; and the Special Olympics World Games 2023, which is officially recognized as the highest level of competitive sports under the Special Olympics framework.

The participation of these athletes in such high-level competitions further confirms their classification as athletes with intellectual disabilities, as they were required to meet the rigorous eligibility standards established by the Special Olympics at the national and international levels.

Three of the athletes have cardiovascular comorbidities. These conditions included bradycardia, supravalvular aortic stenosis, and a history of Tetralogy of Fallot corrected by surgery (Table 1). The remaining three athletes had no cardiovascular comorbidities.

The mean age of the athletes was 21.5 years (±4.28). All six athletes were participants in the unified basketball program of the Special Olympics (SO). Three of the athletes had six years of basketball experience and had achieved success at the international level, while the remaining three had one year of experience in unified basketball with no prior competition history. Based on their athletic achievements and competitive criteria, these athletes represented the national unified basketball team for the Special Olympics in Bulgaria.

Data collection was conducted over a three-month period, during which 20 structured basketball training sessions were held, and five matches were played as part of the SO European Unified Basketball Championship in Druskininkai, Lithuania. No data were collected from local competitive matches due to the absence of a national unified basketball sports calendar.

Training sessions were held twice a week and included four sport partners, in accordance with the rules and regulations of the SO Unified Sports^® competitive model. Each session lasted 90 min and consisted of specific basketball drills focused on skill development, 1-on-1, 2-on-2, and 3-on-3 exercises, as well as half-court and full-court practices. Additionally, sessions incorporated athletic conditioning and strength training. Each training session concluded with a 5-on-5 full-court game. If fewer players were available, the format was adjusted to 4-on-4 or 3-on-3, but games were still played on a full court.

During each training session, athletes wore the specialized Polar Verity Sense heart rate sensor, an optical device designed to monitor heart rate. The same device was used during all five matches played at the SO European Unified Basketball Championship in Druskininkai, Lithuania, held from 17 June to 20 June 2024, with authorization for in-game use.

The Polar Verity Sense heart rate sensor tracked training load zones and calculated key metrics, including average %HR and %HRmax, during both training sessions and matches. The key HR metrics collected included the following:

• Resting heart rate (HRrest).
• Average HR during practices and games (HRavg).
• Maximum HR (HRmax).
• Percentages of HRmax achieved during various activities.

To ensure accurate and reliable HR measurement, several validation procedures were implemented throughout the study. Prior to each training session or competition game, participants were instructed on proper sensor placement and wearing technique, following the manufacturer’s recommendations for the Polar Verity Sense heart rate monitor.

According to Polar Electro Oy (2023) [35], the Polar Verity Sense allows full freedom of movement across various sports, provided it is placed snugly and firmly against the skin. To ensure optimal HR detection, participants were required to undertake the following:

• Place the sensor into the armband holder with the lens facing up.
• Wear the armband so that the sensor sits firmly against the skin on the underside of the armband.
• Secure the Verity Sense armband around the forearm or upper arm (not the wrist) to maintain stable and accurate HR readings.

To minimize movement artifacts and signal loss, sensor placement was undertaken and verified by the research team before each session (Figure 1).

Additionally, post-session HR data were reviewed for anomalies, missing values, or irregular signal drops. If inconsistencies were detected, the session was either re-examined or excluded from final analysis to maintain data integrity.

2.1. Procedure for Determining HRrest and HRmax During Training

A good practice for measuring resting heart rate (HRrest) involves recording the athlete’s pulse for one minute while seated and at rest [36]. In unified basketball, as in traditional basketball, exercises encompass a wide range of intensities, workloads, volumes, and types of activity, including drills performed with and without the ball. Heart rate monitoring in mainstream sport enables coaches to assess and categorize training loads into aerobic (up to 50% intensity), mixed aerobic–anaerobic (50–70%), and anaerobic (70–95%) zones [37]. HR is linearly related to oxygen consumption and energy expenditure during sustained activity. During the HR monitoring, the exercise intensity and workload thought the training sessions should be recorded [27,28,38,39,40].

The HR values during the trainings is traditionally evaluated at submaximal (HRex) and maximal effort (HRmax) levels using incremental tests to assess cardiovascular fitness [28,36,41]. Basketball training frequently incorporates exercises that vary player numbers or adjust game rules to manipulate physical and tactical tasks [42].

Currently, there is a lack of data on HRrest and HRmax that are specific to athletes in unified basketball. This absence limits the ability to compare measured values to standardized benchmarks. To determine HRmax in a field setting, a basketball-specific exercise was employed. This drill, commonly used in 90% of training sessions, was chosen to minimize psychological stress and emotional strain that could influence heart rate. Familiarity with the exercise ensured accurate HRmax measurements without unnecessary mental or emotional interference.

2.2. Exercise Description

The exercise is performed on a full basketball court with three players and one ball. The players pass the ball four times, followed by a shot at the basket (Figure 2a). After the shot, all three players—designated as player #1, player #2, and player #3—compete for the rebound. Once the rebound is secured, they return to the same lane for the next sequence. The first pass of each sequence is always made to the right, allowing each of the two shooting players (players #2 and #3) to take three shots each (Figure 2b). Player #1 does not shoot and focuses solely on rebounding under the basket.

The exercise consists of six lengths of the court performed consecutively without breaks. This drill is highly intense for the participants as it integrates basketball skills and movement following a shot, which are critical components of gameplay. To reduce complexity, the drill is performed without switching lanes.

On average, each sequence is completed in 33.58 to 35.00 s, depending on player #1’s efficiency when rebounding. The rest time between sequences is 149.74 s, which corresponds to the time it takes for the other three-player groups to complete their turn. The exercise is performed three times per session. After each attempt, heart rates were monitored for one minute, and the average heart rate across the three attempts was recorded for analysis.

Frequency analysis and variation analysis were applied.

2.3. Limitations of Heart Rate Monitoring in Unified Basketball Athletes

2.3.1. Internal Factors

Heart rate (HR) responses can naturally vary on a day-to-day basis due to changes in the internal physiological and psychological environment. Several factors contribute to these variations.

Hydration status: Dehydration (hypohydration) can lead to a reduction in blood volume, which decreases stroke volume and consequently increases HR to maintain cardiac output [26].

Individual cardiovascular system: Variability in cardiovascular function, particularly in athletes with comorbidities, can result in unpredictable HR responses.

Dietary habits: Nutritional intake can influence energy availability, leading to an increase or decrease in HR depending on the athlete’s diet.

Emotional state: Anxiety or heightened emotional states can accelerate HR. Training sessions often occur in the evening, and athletes may have experienced a “bad day,” making it challenging to conduct productive sessions until the athlete is calmed by a coach. The presence of new individuals in the team or training facility can also trigger emotional responses.

2.3.2. External Factors

Environmental conditions significantly impact HR responses, including the following:

Temperature extremes:

High temperatures: HR increases to support thermoregulation during physical exertion in hot conditions.

Low temperatures: HR slows down as blood vessels constrict to preserve core body heat in cold environments.

High humidity: Elevated humidity levels can cause an increase in HR as the body works to circulate blood to the skin’s surface for cooling.

2.3.3. Specific Factors Related to Unified Basketball Training

HR reduction during instruction: Unified basketball training often involves interruptions for the explanation of drills, correction of techniques, or to give individual instructions. These pauses can slow HR and disrupt training continuity. This is particularly common in unified basketball, where athletes rely on partners for guidance, and partners’ habits from traditional basketball often require correction.

HR elevation due to non-physical exertion-related factors: Elevated HR is not always a result of physical exertion but may arise from emotional or psychological triggers, such as frustration over mistakes or dissatisfaction with a situation. In some cases, athletes may become emotionally overwhelmed, necessitating immediate intervention to calm them. The athlete is typically given time to rest until their HR returns to baseline (HRrest), which disrupts the balance and flow of the training session.

2.4. Limitations Due to the Small Number of Participants

This pilot study included only six participants, which limits the ability to generalize findings to the broader population of unified basketball athletes. Small sample sizes increase the risk of sampling bias and reduce the external validity of the results. The limited number of participants decreases the statistical power of the study, making it challenging to detect subtle but potentially meaningful differences or trends in heart rate (HR) responses during training and matches. With such a small sample, individual differences—such as variations in cardiovascular health, physical fitness, and psychological state—may disproportionately influence the results. This makes it difficult to draw conclusions about patterns or norms for unified basketball athletes as a group. Half of the participants had cardiovascular comorbidities, introducing additional variability that could mask or amplify observed trends. This highlights the need for larger and more diverse samples to account for these factors.

These challenges are common in adapted sports research and elite mainstream sports, where small participant pools, such as those in wheelchair basketball, football and other team sports, limit the ability to draw robust conclusions about physiological, psychological, social, and health outcomes for individuals with and without disabilities [43,44,45,46,47]. Similarly, studies focusing on populations with cerebral palsy and traumatic brain injury face difficulties in achieving statistical power and generalizability [48,49].

Nevertheless, this pilot study framework offers exploratory insights that can guide larger, more comprehensive research. The study highlights the importance of HR monitoring tailored to athletes with intellectual disabilities, addressing their unique physiological and psychological needs. It also contributes preliminary data to the under-researched field of unified basketball, particularly regarding HR responses during training and competition. HR monitoring provides an objective method by which to adjust training intensity and enhance safety, especially for athletes with communication challenges. The findings support global efforts to advance inclusive sports by informing coaching strategies and improving accessibility for athletes with intellectual disabilities.

These internal and external factors, along with the unique characteristics of unified basketball training, highlight the limitations of HR monitoring as a sole metric for evaluating training intensity or performance. Coaches must consider these variables when interpreting HR data and adapt training plans to accommodate the individual needs and conditions of athletes.

2.5. Ethical Consideration

The study was conducted according to the guidelines of the Declaration of Helsinki, and approval by the ethical approval for the study was obtained from the National Sports Academy, Sofia, Bulgaria (Ref: EC-NSA-2024-0001/15.01.2024).

3. Results

3.1. Training Heart Rate Responses in Unified Basketball Athletes

Maximum heart rate (HRmax) is defined as the theoretical maximum number of heart beats per minute and is commonly used to determine optimal heart rate ranges during physical activity. To date, no specific data exist regarding the HRmax and average heart rate (HRavg) for athletes in unified basketball.

For HR monitoring, we employed one of the most widely used methods for estimating HRmax: HRmax = 208 − (0.7 × age in years). While this formula is considered more accurate than traditional methods, it provides only an approximation and may vary significantly depending on individual characteristics, fitness levels, physical activity, and overall health.

It is important to note that 50% of unified basketball athletes in this study had cardiovascular comorbidities. Determining HRavg and HRmax across the athletes with intellectual disabilities should be highly individualized, making generalizations or broad comparisons inappropriate. Each athlete’s heart rate profile represents a unique case requiring personalized analysis and monitoring to ensure safe and effective training.

Collected data from the training sessions presented in

Table 2. Heart rate data during training.

Athletes	HRrest for 1 min (bpm)	HRmax 208 − (0.7 × Years) (Calculated)	HRmax for 1 min (Actual)	Average HR (bpm)	Average HR (%)	HRmax (bpm)	HRmax (%)
1	81.00	192.6	144.00	108.00	75.00	132.00	68.00
2	66.00	189.8	183.00	112.00	72.50	152.00	76.00
3	67.00	189.8	187.00	136.00	67.38	175.00	73.00
4	80.00	196.8	164.00	121.00	66.90	154.00	55.00
5	57.00	192.6	203.00	137.00	61.20	175.00	63.00
6	73.00	196.1	176.00	118.00	73.72	162.00	67.00

are the resting heart rate (HRrest), calculated maximum heart rate (HRmax), actual HRmax, average heart rate (HRavg), and corresponding percentages of HRmax for the six unified basketball athletes during the training process. The percentage data were recorded using Polar heart rate sensors.

As illustrated in Table 2, there are noticeable variations in HRrest values among the six athletes. The calculated HRmax values, derived from the formula HRmax = 208 − (0.7 × age), exhibit significant discrepancies when compared with the actual HRmax values obtained through monitoring. Notably, only athlete #3’s actual HRmax (187 bpm) closely aligns with the calculated HRmax (189.8 bpm). For the remaining athletes, the discrepancies are considerable, underscoring the limitations of applying generalized formulas to this population.

These findings highlight the necessity of individualized heart rate assessments using specialized equipment for unified basketball athletes participating in the Special Olympics (SO) program. Due to their unique physiological and health profiles, these athletes cannot be accurately categorized using standard heart rate norms designed for basketball players or general athletes.

During training, the athletes predominantly operated at an average intensity of up to 75% of their HRavg. However, athlete #2 reached a peak intensity of 76% HRavg. This emphasizes the importance of tailoring training programs to the athletes’ sports experience, motor skills, physical fitness, individual characteristics, and psychological state.

Overall, these data underscore the need for training programs that account for the athletes’ specific characteristics, experience, and readiness to ensure optimal performance and safety during training sessions.

3.2. Gameplay Heart Rate Responses in Unified Basketball Athletes

In

Table 3. Heart rate data during games.

Athletes	HRrest for 1 min (bpm)	HRmax for 1 min (bpm)	HRavg (bpm)	HRavg (%)	HRmax (bpm)	HRmax (%)
1	81.00	144.00	97.00	68.00	122.00	84.00
2	66.00	183.00	113.0	63.00	157.00	86.50
3	67.00	187.00	143.00	76.00	180.00	94.00
4	80.00	164.00	108.00	67.00	148.00	90.00
5	57.00	203.00	145.00	73.00	181.00	88.50
6	73.00	176.00	95.00	55.00	143.00	82.50

are presented the resting heart rate (HRrest), maximum heart rate (HRmax), average heart rate (HRavg), and corresponding percentages of HRmax for the six unified basketball athletes during official 5-on-5 games. The percentage data were recorded using Polar heart rate sensors.

The average heart rate (HRavg) during matches reached up to 145 bpm, with HRavg percentages peaking at 76%. The maximum heart rate (HRmax) recorded was 180 bpm, a value commonly observed in professional basketball players. One athlete achieved 94% of their HRmax during gameplay, while the lowest recorded value for %HRmax was 82.50%. These results indicate a consistently high level of physical exertion among all athletes during official matches.

In addition to physical demands, psychological factors play a significant role in unified basketball matches. The absence of a national unified basketball sports calendar in Bulgaria for 5-on-5 games poses a challenge for athletes. Without regular competition, athletes struggle to develop the game rhythm and mental preparedness necessary for optimal performance in 5-on-5 formats.

Games are played on a standard basketball court measuring 28 m in length and 15 m in width. During transitions between offense and defense, all players must cross the midcourt line, requiring at least 14 m of sprinting at game speed, while the shot clock in basketball is 24 s, gameplay involves frequent multidirectional movements such as forward and backward running, lateral shuffling, jumping, landing, ball handling, and physical contact with opponents. Additionally, opponents are often unfamiliar, as international tournaments feature numerous teams and divisions, ensuring new matchups each time.

3.3. Comparative Analysis of Average Heart Rate During Training and Games

A comparative analysis of the average heart rate (HRavg) of athletes during training and matches was conducted (Figure 3). Three athletes demonstrated a negative difference, with their HRavg during matches being lower than during training. This is unusual, as the tension, rhythm, and intensity of matches—especially when playing against unfamiliar opponents—would typically result in higher HRavg values.

The observed differences range from −11 to −23 bpm, suggesting that these athletes may not fully understand the purpose of competition or the concept of unified basketball. This notion was confirmed by a comment made by the technical delegate during the SO European Unified Basketball Championship regarding these three athletes’ difficulties to meet the principle of meaningful involvement (POMI). Unified basketball emphasizes shared responsibility between athletes with intellectual disabilities and their sport partners, requiring active participation from all players. The lower HRavg values indicate that these three athletes may have isolated themselves from the game, limiting their activity and leaving their teammates—both athletes and sport partners to assume a more active role.

This behavior is inconsistent with the core principle of unified basketball, the principle of meaningful involvement (POMI), which ensures equitable participation for all players. These findings warrant reflection by the coaching staff, as well as consideration of alternative approaches for these athletes. One potential solution is transitioning these players to a 3 × 3 basketball format, which is played on a half court with a single basket. The 3 × 3 format reduces transitions and physical demands while increasing ball involvement, potentially fostering greater engagement and activity for these athletes.

3.4. Comparative Analysis of Maximum Heart Rate During Training and Games

A comparative analysis of the maximum heart rate (HRmax) during training and matches was conducted (Figure 4).

For all athletes, HRmax values were higher during matches than during training. These results align with expected values, considering the psychological pressure athletes experience at specific moments during a game.

The rules of unified basketball prohibit verbal instructions from partners and coaches, allowing only supportive gestures or actions. This limitation can be stressful for athletes who lack prior game experience. However, as athletes participate in more matches, their gameplay experience gradually becomes habitual, reducing stress levels over time.

While the data indicate that athletes reach their HRmax during matches, the duration for which they sustain these maximum values was not analyzed in this study.

Table 4. Variation statistics of the analyzed indicators.

Indicators	n	X min	X max	R	X	S	V (%)	As	Ex
1. HRrest (1 min)	6	57.00	81.00	24.00	70.67	9.180	12.99	−0.300	−0.871
2. HRmax (1 min)	6	144.00	203.00	59.00	176.17	20.330	11.54	−0.506	0.415
3. Average HR training	6	108.00	137.00	29.00	122.00	12.120	9.93	0.390	−1.777
4. HRmax (training)	6	132.00	175.00	43.00	158.33	16.260	10.27	−0.649	0.138
5. Average HR (game)	6	95.00	145.00	50.00	116.83	22.090	18.91	0.593	−1.884
6. HRmax—(game)	6	122.00	181.00	59.00	155.17	22.750	14.66	−0.155	−0.862

presents the variation statistics for all analyzed indicators.

The values for all analyzed indicators exhibit a normal distribution, as confirmed by the following critical values for the sample: As_0.05 = 1.374 and Ex_0.05 = 2.668. The coefficients of variation (V) for average HR (training) (V3 = 9.93%) and HRmax (training) (V4 = 10.27%) indicate group homogeneity. These values reflect proper training practices by the coaches, with loads adjusted to the individual capabilities of the athletes.

In sports statistics, a coefficient of variation V ≤ 12% typically indicates group homogeneity. For HRmax (1 min) (V2 = 11.54%), the group also demonstrates homogeneity. However, relative heterogeneity is observed for HRrest (1 min) (V1 = 12.99%), average HR (game) (V5 = 18.91%), and HRmax (game) (V6 = 14.66%).

This variability is unsurprising, as 50% of the athletes have previous experience in European and world championships, while the remaining 50% were participating in an official competition for the first time.

3.5. Preliminary Insights for Unified Basketball Coaches and Sport Professionals on HR Monitoring Integration and Training Strategies

Heart rate (HR) monitoring offers a valuable, objective method for enhancing training, performance, and safety in unified basketball. Based on the results from the research some preliminary insights for coaches and sport professionals can be provided.

In order to enhance safety, coaches should be familiar with athletes’ medical records/journals. Athletes with intellectual disabilities often have comorbidities that impact cardiovascular function. HR monitoring enables coaches to ensure training loads are within safe limits, minimizing the risk of overexertion or cardiovascular strain.

HR recovery data can provide insights into an athlete’s physical condition during practice or games. Prolonged recovery may signal excessive fatigue, allowing coaches to adjust the intensity or duration of activities accordingly.

External factors, such as temperature and humidity, can significantly impact HR. Coaches can use HR data to modify practice conditions, ensuring athletes remain within safe HR zones during extreme weather.

Coaches closely monitor the athletes’ %HRmax, as they often reach their maximum heart rate quickly. This rapid increase is not only due to physical exertion but also influenced by emotional factors, such as unfamiliar exercises, the presence of new people, or external stimuli. For these athletes, any unexpected change can act as a stressor, triggering varied reactions.

To minimize these effects, it is strongly recommended to train in a consistent environment—using the same facility, with familiar people, and minimizing the introduction of new exercises (ideally limiting new content to no more than 15% of the session). Additionally, the presence of external individuals should be avoided to maintain a stable and predictable atmosphere conducive to effective training.

Promoting meaningful involvement (POMI): The principle of meaningful involvement emphasizes equitable participation for all athletes in unified basketball. Data suggest that athletes who handle the ball more frequently during games tend to exhibit higher HRmax values due to increased physical and psychological demands. Coaches should monitor these responses and ensure balanced ball-handling responsibilities across all players during training sessions. This approach reduces fatigue for individual athletes and promotes inclusivity.

Simulating competitive intensity in training: Findings indicate that HRmax levels during official matches are significantly higher due to the intensity and pace of gameplay. To prepare athletes for these demands, coaches should incorporate high-intensity drills into training sessions. Full-court exercises that simulate competitive conditions, such as rapid transitions between offense and defense, are particularly effective in achieving cardiovascular stress levels comparable to those in matches.

Using small-sided games to enhance engagement and intensity: Reducing player numbers in scrimmage drills, such as 3 on 3, increases individual involvement and elicits higher HR responses [41,42]. This format can be strategically implemented to replicate match-like conditions and promote meaningful engagement for all athletes, especially those less experienced in competitive play. Although practitioners often implement reduced court size to improve technical components, the application of full-court drill configurations promotes greater cardiovascular stress in response to more high-intensity activity transitioning the ball across the court [50,51].

Adapting training to team dynamics: Training drills should be designed to distribute physical and technical demands among all participants evenly. Coaches can achieve this by tailoring drills to the unique needs of the team, considering individual fitness levels, game experience, and psychological readiness.

Balancing psychological and physical loads: Elevated HR during matches is often influenced by psychological factors such as game pressure and unfamiliar opponents. Coaches can mitigate these effects by fostering familiarity in training environments and gradually exposing athletes to match-like scenarios to build confidence and resilience.

The integration of HR monitoring technology into the training and competition processes of unified basketball enables the real-time tracking of HR data, as well as the physiological changes and reactions of athletes during exercise interruptions. Berkelmans et al. (2018) have summarized the principles applicable to basketball training, and these are also highly relevant to athletes in unified basketball [27].

Monitoring exercise intensity during basketball training and gameplay should include relative HR values (%HRmax) and the distribution of time spent in different intensity zones (low, moderate, and high). This allows for individualized comparisons among players and offers a more comprehensive understanding of the cardiovascular stress experienced during activities.

Reporting time spent in HR zones provides coaches with critical insights into the distribution of activity intensities. This method avoids relying solely on mean or peak HR values, which can be influenced by various stimuli, and instead gives a clearer picture of the overall demands on athletes.

HR data, particularly when monitored during both live and total playing time, highlights the physiological demands placed on athletes, including recovery periods. This information enables basketball practitioners to make informed decisions regarding individualized training plans, effective recovery strategies, and in-game tactical decisions that provide recovery opportunities for players [27].

By adopting HR monitoring practices, coaches can better tailor training and competition strategies to meet the unique needs of unified basketball athletes, enhancing performance, safety, and inclusivity.

The absence of prior data on HR and HRmax for unified basketball athletes means that the results obtained in this study should not be regarded as a universal model. Instead, HRmax determination serves as a critical factor for developing a functional training concept tailored specifically to this team.

This study revealed differences in HRaverage, HRmax, and their percentages between training sessions and matches. While HR monitoring provides valuable insights into the internal responses of athletes, it is equally important to account for external load factors, which influence the dose–response relationship of HR.

The unique nature of unified basketball requires the integration of both internal and external load data to plan training loads more safely and effectively. Training plans should be individualized, considering each athlete’s skill level, phase of development, competition schedule, and adherence to the principle of meaningful involvement (POMI).

By using HR data in conjunction with external load metrics, coaches can create safer, more personalized training programs that align with the specific needs and objectives of unified basketball athletes.

4. Discussion

This pilot study examined heart rate (HR) responses in athletes with intellectual disabilities engaged in unified basketball, emphasizing the utility of HR monitoring for optimizing training regimens, managing fatigue, and enhancing athletic performance. The findings contribute to the scarce body of research focused on HR monitoring in unified basketball, offering insights into the physiological demands placed on athletes with intellectual disabilities and underscoring the importance of individualized training strategies.

The data revealed considerable individual variability in HR responses among the six participants. This variability was primarily influenced by factors such as cardiovascular health status, baseline physical fitness, and prior experience in basketball. HR monitoring uncovered distinct patterns, particularly in athletes with cardiovascular comorbidities such as bradycardia and supravalvular aortic stenosis. These conditions significantly impacted both average working HR and maximum HR thresholds, highlighting the necessity of personalized monitoring protocols and tailored training interventions. These findings are consistent with previous studies, indicating that participants in adaptive sports often experience physiological constraints stemming from pre-existing health conditions, necessitating a more nuanced approach to training and performance optimization [5,6,10].

Beyond physiological factors, psychological and environmental conditions were critical in shaping HR responses. Elevated HR levels during both training sessions and competitive matches were linked to psychological stressors, such as performance anxiety and unfamiliarity with competitive settings. Environmental variables—including fluctuations in temperature, humidity, and the presence of unfamiliar individuals during practice—further influenced HR variability. These observations align with prior research identifying psychological barriers faced by individuals with intellectual disabilities in sports contexts, such as reduced self-confidence and heightened sensitivity to environmental stimuli [3,4,9]. Addressing these challenges requires the development of structured, supportive training environments that mitigate stress and foster psychological security, thus promoting more consistent physiological responses.

Inclusive sports programs, exemplified by unified basketball, have been shown to contribute to the physical development of athletes with intellectual disabilities significantly. Participants demonstrated notable improvements in overall fitness levels, motor coordination, and sport-specific skills throughout the study period. These findings corroborate existing literature emphasizing the physical and motor benefits of inclusive sports participation [20,21]. Enhanced physical performance was accompanied by improvements in general health and well-being, with the confidence gained through skill development serving as a strong motivator for continued participation in both inclusive sports and other physical activities [52,53,54].

The success of inclusive sports programs is intrinsically linked to the expertise, knowledge, and dedication of coaches. HR monitoring could be an invaluable supportive tool, offering detailed insights into player-specific endurance levels and tactical engagement during high-intensity game scenarios [55]. Continuous tracking of HR responses could enable coaches to fine-tune training intensity, manage fatigue, and adjust workloads in accordance with each athlete’s unique physical capabilities. These practices align with the broader literature emphasizing the need for comprehensive coach training programs to equip them with the skills necessary to support athletes with intellectual disabilities effectively [23,24]. Furthermore, HR monitoring could provide objective feedback on exertion levels, particularly for athletes who face challenges in articulating their physical condition, thereby addressing a critical gap in traditional coaching methodologies. However, for a comprehensive assessment of an athlete’s overall health and readiness, HRV should be considered alongside other internal and external load factors to provide a more accurate evaluation [56].

A comparative analysis of HR responses during training and official matches revealed that most athletes exhibited higher HRmax values during competitive play, reflecting the increased physical and psychological demands of match conditions. However, three participants displayed lower average HR during matches compared with training sessions, suggesting potential disengagement or difficulty adapting to the competitive environment. This finding calls attention to the principle of meaningful involvement (POMI), which underscores the importance of equitable participation in unified sports. Ensuring that all athletes are meaningfully engaged in both training and competition is essential for realizing the full benefits of inclusive sports programs [17,25].

The primary limitation of this study lies in the small sample size, which restricts the generalizability of the findings to the broader population of unified basketball athletes. With only six participants, individual differences in cardiovascular health, physical fitness, and psychological factors may have disproportionately influenced the results. The presence of cardiovascular comorbidities in half of the participants introduced further variability, potentially masking or amplifying observed trends. Such challenges are common in adapted sports research, where limited participant pools, as seen in sports like wheelchair basketball, constrain the ability to draw robust conclusions regarding physiological, psychological, and health outcomes [45,46]. Similar methodological constraints are observed in studies focused on populations with cerebral palsy and traumatic brain injury, which often struggle to achieve sufficient statistical power and external validity [48,49]. The literature indicates that working with small samples is not uncommon in traditional sports research. Studies in both basketball and football, sports with widespread participation, have employed limited sample sizes to derive meaningful conclusions [43,44,47]. For instance, ref. [47] analyzed the HR of just eight elite basketball players, demonstrating that valuable insights can still be obtained despite sample size constraints.

Despite these limitations, this pilot study offers valuable exploratory insights that can inform future, more comprehensive research endeavors. The findings underscore the critical role of HR monitoring in addressing the unique physiological and psychological needs of athletes with intellectual disabilities. By providing objective data to guide training intensity, manage fatigue, and enhance athlete safety, HR monitoring presents a promising avenue for improving coaching strategies and overall athletic performance. Moreover, this study contributes preliminary data to the under-researched field of unified basketball, supporting global initiatives aimed at advancing inclusive sports and enhancing accessibility for athletes with intellectual disabilities.

5. Conclusions

This pilot study examined heart rate (HR) responses in athletes with intellectual disabilities participating in unified basketball to assess the physiological demands of the sport and evaluate individual variability in HR patterns. The findings revealed notable differences in both average HR and maximum HR (HRmax) among the six participants, influenced by factors such as cardiovascular health, fitness levels, and basketball experience.

Athletes with cardiovascular comorbidities, including bradycardia and supravalvular aortic stenosis, demonstrated distinct HR responses, which affected their average working HR and HRmax during both training sessions and matches. Most athletes exhibited higher HRmax during competitive games when compared with training, reflecting the increased physical and psychological demands of match play. However, three athletes showed lower average HR during matches than in training sessions, indicating variability in physical exertion or engagement during competition.

The pilot study also highlighted the impact of environmental and emotional factors on HR responses. External conditions, such as temperature and humidity, along with psychological stressors related to competition, contributed to fluctuations in HR data. These findings emphasize the importance of considering both physiological and contextual factors when evaluating athlete performance.

While the small sample size limits the broader applicability of the findings, this study provides important preliminary insights into the HR responses of unified basketball athletes. The results support the value of HR monitoring as a tool for understanding the physiological demands of the sport and for informing individualized training approaches tailored to the specific needs of athletes.