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  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Personalizing Exercise Recommendations with Explanations using Multi-Armed Contextual Bandit and Reinforcement Learning⋆</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Parvati Naliyatthaliyazchayil</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Deepishka Pemmasani</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Navin Kaushal</string-name>
          <email>nkaushal@iu.edu</email>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Donya Nemati</string-name>
          <email>nemati.9@osu.edu</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Saptarshi Purkayastha</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>College of Nursing, The Ohio State University</institution>
          ,
          <addr-line>Ohio</addr-line>
          ,
          <country country="US">USA</country>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>Dept. of Biomedical Engineering and Informatics, Indiana University Indianapolis</institution>
          ,
          <addr-line>Indianapolis, Indiana</addr-line>
          ,
          <country country="US">USA</country>
        </aff>
        <aff id="aff2">
          <label>2</label>
          <institution>Dept. of Health Sciences, Indiana University Indianapolis</institution>
          ,
          <addr-line>Indianapolis, Indiana</addr-line>
          ,
          <country country="US">USA</country>
        </aff>
      </contrib-group>
      <abstract>
        <p>We present an innovative mobile exercise recommendation app that leverages clinical guidelines from authoritative sources to provide personalized, safe exercise suggestions. Our approach addresses two critical challenges in health-focused recommender systems: the cold start problem and user motivation through explainable AI. To overcome the initial lack of user data, we employ a two-stage process: We use Deep Q-Network (DQN) reinforcement learning to generate 2000 synthetic user profile. The DQN learns a reward function based on clinical guidelines, ensuring that the generated profiles align with established medical advice. These synthetic profiles bootstrap a multi-armed contextual bandit algorithm. This algorithm recommends the most suitable exercises for a given user persona, determined by a combination of comorbidities, age, and preferred exercise criteria. Our method's key innovation lies in its ability to mimic a large cohort of clinically safe user profiles without requiring real-world participants, efectively eliminating the cold start problem while maintaining medical appropriateness. To enhance user engagement and promote behavior change, we implement an explainability layer. Unlike black-box deep learning recommenders, our system provides transparent justifications for each recommendation. By highlighting the importance of specific features used in the decision-making process, we help users understand why a particular exercise is recommended for their persona. This recommender system is being incorporated into an existing mobile app, which will be trialed with healthy and cardiovascular disease patients.</p>
      </abstract>
      <kwd-group>
        <kwd>eol&gt;Mobile Health</kwd>
        <kwd>Exercise Recommender System</kwd>
        <kwd>Reinforcement Learning(RL)</kwd>
        <kwd>Explainable AI Deep Q-Network</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>1. Introduction</title>
      <p>
        Physical exercise, widely recognized as a "miracle cure," remains underutilized despite its critical role in
health maintenance and chronic disease management [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ]. The World Health Organization reports that
approximately one-third of the global adult population—1.8 billion individuals—are physically inactive
[
        <xref ref-type="bibr" rid="ref2">2</xref>
        ]. A primary reason for this is that though people easily form habits around everyday activities,
exercise is often something that is contemplated rather than consistently practiced. However, by turning
exercise into a regular habit, individuals can significantly change their exercise behavior for the better
and improve their health outcomes.
      </p>
      <p>
        To address this, we have developed a novel mobile recommender that provides personalized exercise
recommendations based on clinical guidelines, helping users build and sustain exercise habits. With
mobile devices becoming integral to daily lives, mobile Recommender Systems (RS) have gained traction
in healthcare interventions, though their application to physical activity promotion remains limited [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ].
      </p>
      <p>
        This is due to challenges such as the "user cold start" problem, limited data for analytics [
        <xref ref-type="bibr" rid="ref4 ref5">4, 5</xref>
        ], and the
opaque nature of Deep Reinforcement Learning (DRL) algorithms [
        <xref ref-type="bibr" rid="ref6">6</xref>
        ]. Our research addresses these
challenges by leveraging trusted clinical guidelines and incorporating an explainability layer, making
the system reliable, safe, and personalized to the user’s medical history and needs.
      </p>
      <p>
        The user cold start problem, which arises when there is insuficient behavior information about new
users, has been addressed in various ways in the literature. Approaches include clustering existing
users to predict new user behavior [
        <xref ref-type="bibr" rid="ref4">4</xref>
        ], employing multi-phase algorithms for user classification,
getting neighbours and outcome prediction [
        <xref ref-type="bibr" rid="ref7">7</xref>
        ], and few systemic reviews summarizing methods used
including using auxiliary data to augment user profiles as data approach and using various Machine
Learning algorithms along with content based algorithms as method driven approach.[
        <xref ref-type="bibr" rid="ref8">8</xref>
        ]. Our approach
uniquely integrates clinical guidelines practices into synthetic user profiles that can be used to train the
recommender, overcoming this issue. For this, we employ a two-stage process:
• Collecting the exercise recommendation guidelines for various medical conditions from their
respective authoritative sources and structuring it into Machine Learning consumable format for
further utilization.
• Utilizing DQN to generate 2,000 synthetic user profiles using structured clinical guidelines from
step-1 ensuring the generated profiles align with established medical advice.
      </p>
      <p>These synthetic profiles are used to train Multi-Armed Contextual Bandit (MAB) algorithm which
recommends exercises making it extremely safe and useful when we don’t have past behavior history.
While these generated recommendations are clinically safe, they are also tailored to fit along with the
other user choices like having a workout buddy or exercising at home etc., This efectively replaces
the need for real-world data for training, thus addressing the cold start problem and lack of publicly
available datasets, while ensuring medical accuracy.</p>
      <p>
        To enhance user engagement and promote behavior change, we incorporate an explainability layer
into our system. This approach aligns with Explainable Artificial Intelligence (XAI) principles, which
aims to provide transparency in algorithmic decision-making processes [
        <xref ref-type="bibr" rid="ref9">9</xref>
        ]. Research indicates that
an improved understanding of treatment correlates with better adherence [
        <xref ref-type="bibr" rid="ref10 ref11">10, 11</xref>
        ] and can enhance
engagement and foster behavior change [
        <xref ref-type="bibr" rid="ref12">12</xref>
        ].
      </p>
      <p>Our recommender system is being integrated into an existing mobile application and will be tested
with both healthy individuals and those with cardiovascular conditions. This research contributes to
the growing field of personalized digital health interventions by addressing key challenges in exercise
recommendation systems.</p>
    </sec>
    <sec id="sec-2">
      <title>2. Methodology</title>
      <p>The design of our novel exercise recommendation system comprises three main components: guideline
structuring, Deep Q-Network (DQN) for synthetic data generation, and a Multi-Armed Contextual
Bandit (MAB) algorithm for personalized recommendations. We also incorporate an explainable AI
(XAI) layer to enhance transparency and user engagement.</p>
      <sec id="sec-2-1">
        <title>2.1. Guideline Structuring and Base File Creation</title>
        <p>
          The goal of this step is to structure exercise guidelines from authoritative sources (e.g., American Heart
Association, National Kidney Foundation) into a standardized and consumable format by DQN. The first
step to structuring unstructured guidelines is to identify key attributes available commonly across most
guidelines. Key attributes that were identified were age, gender, medical history, exercise preference,
frequency, and duration. Next, the value of each attribute was collected from each guideline used. For
e.g., value of attribute ’exercise preference’ is cardio if the guideline refers to preferred exercise being
walking or running. Each unique combination of attribute values was assigned a reward score (0-1)
based on adherence to guidelines. For e.g., the American Heart Association(AHA) recommends at
least 150 minutes of moderate-intensity aerobic activity per week, with additional benefits for patients
with cardiac diseases who engage in at least 300 minutes (5 hours) per week [
          <xref ref-type="bibr" rid="ref13">13</xref>
          ]. Consequently while
structuring this guideline a record with 30-45 minutes of aerobic activity per day for 5 days a week will
receive a higher "reward" compared to a record with 15-30 minutes of activity per day for 3 days a week
because 30-45 minutes of activity for 5 days a week closely aligns with AHA guideline in this example.
Other examples of exercise guidelines include the National Kidney Foundation’s recommendation
for continuous activity involving large muscle groups, aiming for 30-minute sessions [
          <xref ref-type="bibr" rid="ref14">14</xref>
          ], and the
American Diabetes Association’s guideline of 150 minutes of moderate-intensity exercise per week [
          <xref ref-type="bibr" rid="ref15">15</xref>
          ].
This structured dataset, termed the "base file," formed the foundation for subsequent steps. Figure 1
shows couple rows from base file showing how the structure looks:
        </p>
      </sec>
      <sec id="sec-2-2">
        <title>2.2. DQN for synthetic data generation</title>
        <p>
          We employed a Deep Q-Network (DQN), a model-free, of-policy reinforcement learning algorithm
[
          <xref ref-type="bibr" rid="ref16 ref17">16, 17</xref>
          ], to generate synthetic user profiles. A user profile is referring to each user’s demographics,
pre-existing medical conditions along with exercise goals and exercise preferences. The DQN system
comprised three main components: environment construction, state representation, and
recommendation policy learning.
        </p>
        <p>
          1. Environment Construction: This phase involves creating an environment based on user behavior
history[
          <xref ref-type="bibr" rid="ref17">17</xref>
          ]. In cold start scenarios, as in our study, the base file, developed in the previous step
according to specific guidelines, is used to construct this environment.
2. State Representation: The environment generates a state representation that typically includes
user demographics and past behaviors[
          <xref ref-type="bibr" rid="ref17">17</xref>
          ]. Our study utilizes demographic data randomly
generated from defined value sets along with the base file data supplementing the absence of
historical behavior for user cold start cases.
3. Recommendation Policy Learning: Guided by rewards derived from the base file’s "reward" column.
        </p>
        <p>This reward value is carefully designed to reflect how closely the exercise recommendations
adhere to clinical guidelines based on user attributes such as age, gender, medical history, exercise
preference, frequency, and duration. Using this structured reward system, the model ensures that
the generated recommendations are safe and tailored to individual needs.</p>
        <p>
          DRL has the unique ability to leverage deep learning to approximate the value function in RL and
solve high-dimensional Markov Decision Processes (MDPs)[
          <xref ref-type="bibr" rid="ref17">17</xref>
          ]. The DQN agent selected actions
(attribute-value pairs) according to the policy at a given state, with rewards determined by matching
rows in the base data. The agent updated its Q-values based on received rewards, learning optimal
actions to generate guideline-adherent profiles. Key hyperparameters included a learning rate of 0.001,
a discount factor of 0.95, an initial epsilon of 1.0, an epsilon decay of 0.995, and a minimum epsilon of
0.01.
        </p>
      </sec>
      <sec id="sec-2-3">
        <title>2.3. Multi-Armed Bandit (MAB) Algorithm Implementation</title>
        <p>
          To develop a personalized exercise recommendation system, we implemented a Multi-Armed Contextual
Bandit (MAB) algorithm using the LinUCB (Linear Upper Confidence Bound) approach [
          <xref ref-type="bibr" rid="ref18">18</xref>
          ]. The system
was designed to learn from and adapt to individual user profiles and behaviors over time, based on a
dataset of 2000 users’ exercise profiles and characteristics.
        </p>
        <p>In our study, the MAB model defined three arms corresponding to the main exercise types: cardio,
strength, and flexibility. The context for each user was represented as a feature vector comprising
demographic information (age, sex, race), medical history, exercise preferences (frequency, duration,
location), and other relevant attributes. To improve the algorithm’s performance, we applied feature
engineering techniques, including normalization of numerical features, one-hot encoding of categorical
variables, and creation of interaction terms.</p>
        <p>
          The LinUCB algorithm was implemented to balance exploration and exploitation in recommendation
selection [
          <xref ref-type="bibr" rid="ref19">19</xref>
          ]. Exploration refers to the algorithm’s attempt to try diferent exercise routines for a
user, even if it is uncertain about their efectiveness, to gather more data. Exploitation, on the other
hand, involves recommending exercises that have already shown positive results[
          <xref ref-type="bibr" rid="ref20">20</xref>
          ].For each arm
a, we maintained a matrix A_a and vector b_a to estimate the coeficients  _a. For instance: For the
cardio arm, A_cardio a matrix that tracks features like age age, sex, race, frequency, duration of the
cardio activity, while b_cardio is a vector representing the corresponding observed rewards like exercise
completion or adherence. At each interaction, the algorithm computed a score for each arm based
on the current context and coeficient estimates, selecting the arm with the highest score. The model
parameters were updated after each interaction using the observed reward, which was defined as a
weighted combination of short-term engagement (exercise completion) and long-term health outcomes
(progress towards weekly goals).
        </p>
        <sec id="sec-2-3-1">
          <title>2.3.1. Incorporating Contextual Information</title>
          <p>
            To further refine the recommendations, we incorporated a contextual bandit model, a variant of
the MAB framework that allows the algorithm to consider additional contextual information before
making decisions[
            <xref ref-type="bibr" rid="ref20">20</xref>
            ]. In our case, context included variables such as age, exercise preference, duration,
frequency and strength preference. By including these contextual factors, the algorithm could tailor
its recommendations more closely to the user’s current state and environment, thereby increasing the
likelihood of user engagement and adherence to the exercise plan. The performance of the MAB-based
recommendation system was evaluated by simulating user interactions with the synthetic data.
          </p>
        </sec>
      </sec>
      <sec id="sec-2-4">
        <title>2.4. Explainable AI Layer (XAI)</title>
        <p>
          To enhance transparency and foster trust, we incorporated an explainable AI layer. This layer provides
insights into the rationale behind specific exercise recommendations, considering user medical history,
user choices, and relevant health guidelines. The XAI component aims to support clinical adoption,
ensure greater accuracy, minimize risks associated with errors or biases, and enhance user engagement
[
          <xref ref-type="bibr" rid="ref21">21</xref>
          ] fostering behaviour change.
        </p>
      </sec>
    </sec>
    <sec id="sec-3">
      <title>3. Results and Discussion</title>
      <p>As outlined in the methodology, we conducted an attribute analysis to identify the key variables and
their respective valuesets necessary for structuring the exercise guidelines to create base file. Upon the
creation of the base file, it was utilized in the DQN model to generate profiles. Key parameters such
as average reward per episode and epsilon decay were monitored to evaluate the Q-agent’s learning
progress and improvement over time. The results indicated a consistent average reward of 0.5 per
episode, suggesting that the model efectively adhered to the guidelines and optimized its performance
as training progressed as shown in 3.</p>
      <p>Additionally, the epsilon value steadily decreased throughout the agent’s lifecycle, demonstrating
that the agent learned to act more optimally with experience, as depicted in the graph below Figure 4.</p>
      <p>To assess the similarity between real and synthetic data, we employed the Kolmogorov-Smirnov
(KS) test, comparing the distributions of various features. Features such as Strength Training, Strength
Preference, Exercise Location, Cardio Preference, Gender, Exercise Duration, Preferred Exercise, and
Medical Exercise yielded high p-values (close to 1), indicating that their distributions in the synthetic data
closely matched those in the real data. This result suggests that the DQN model successfully captured
the essential patterns in the data while also adapting and improving its policy through exploration.</p>
      <p>Additionally, we conducted a Feature Importance Similarity analysis to compare the importance of
features when models were trained on real versus synthetic data. The analysis produced a Feature
Importance Similarity score of 0.9787, indicating a high degree of similarity. This suggests that the
synthetic data efectively captured the critical features. Figure 5 shows a Feature Importance Comparison,
with Age used as the target variable.</p>
      <sec id="sec-3-1">
        <title>3.1. MAB Algorithm Training and Evaluation</title>
        <p>We evaluated the performance of our Multi-Armed Contextual Bandit (MAB) algorithm using the
LinUCB approach over a simulated period of 30 days, with 2000 synthetic user profiles generated by
the Deep Q-Network (DQN). The evaluation focused on the algorithm’s ability to provide personalized
exercise recommendations and adapt to user profiles over time.</p>
        <sec id="sec-3-1-1">
          <title>3.1.1. Convergence and Learning Rate</title>
          <p>The MAB algorithm demonstrated rapid convergence, with the average reward stabilizing after
approximately 15 days of simulated interactions. Figure 6 illustrates the learning curve, showing the daily
average reward across all users.</p>
          <p>The learning rate,  , was set to 0.1, which provided a balance between quick adaptation and stability.
We observed that higher learning rates (e.g., 0.2, 0.3) led to faster initial convergence but increased
volatility, while lower rates (e.g., 0.05, 0.01) resulted in slower learning but more stable long-term
performance.</p>
        </sec>
        <sec id="sec-3-1-2">
          <title>3.1.2. Cumulative Regret</title>
          <p>Cumulative regret, a key metric for evaluating MAB algorithms, measures the diference between the
optimal and actual rewards received over time. Our LinUCB implementation achieved a sub-linear
cumulative regret, as shown in Figure 7.</p>
          <p>The final cumulative regret after 30 days was 487.3, which is 18.9% lower than a standard  -greedy
approach (600.5) and 32.4% lower than a random selection baseline (721.6).</p>
        </sec>
        <sec id="sec-3-1-3">
          <title>3.1.3. Recommendation Accuracy and Diversity</title>
          <p>To assess recommendation diversity, we calculated the Intra-List Distance (ILD) metric, which measures
the dissimilarity between recommended items. The average ILD increased from 0.58 on day 1 to 0.73 on
day 30, suggesting that the algorithm provided a more diverse range of recommendations as it learned
user profiles.</p>
        </sec>
        <sec id="sec-3-1-4">
          <title>3.1.4. Exploration vs. Exploitation Balance</title>
          <p>We monitored the exploration-exploitation trade-of using the percentage of exploratory actions taken
by the algorithm. Figure 8 shows how this percentage changed over time.</p>
          <p>The exploration rate decreased from an initial 40% to approximately 15% by day 30, indicating that the
algorithm transitioned from a more exploratory phase to a more exploitative one as it gained confidence
in its learned preferences.</p>
        </sec>
        <sec id="sec-3-1-5">
          <title>3.1.5. Computational Eficiency</title>
          <p>The average time to generate a recommendation was 12.3 milliseconds (ms) with a standard deviation
of 2.1 ms, measured on a system with an AMD 5900X and 32GB RAM. This performance suggests that
the algorithm is suitable for real-time recommendations in a mobile application setting. We plan to
transfer this to our mobile app, which might be slightly slower in its recommendations but still be fast
enough for acceptable UX.</p>
          <p>In summary, our MAB algorithm demonstrated efective learning, personalization, and adaptation
capabilities in providing exercise recommendations. The results show improvements in recommendation
accuracy and diversity over time, with successful contextual adaptation across diferent user segments.
The sub-linear cumulative regret and eficient computational performance further support the viability
of this approach for personalized exercise recommendation systems.</p>
        </sec>
      </sec>
      <sec id="sec-3-2">
        <title>3.2. Results from the Explainable AI Layer</title>
        <p>The integration of an explainable AI (XAI) layer into our exercise recommendation system yielded
significant improvements in transparency, user understanding, and overall system efectiveness. We
evaluated the XAI layer’s performance using only quantitative metrics, since our mobile app trial will
be in the future.</p>
        <sec id="sec-3-2-1">
          <title>3.2.1. Transparency and Interpretability</title>
          <p>We analyzed the SHAP values for a sample of 2000 synthetic user profiles to understand the relative
importance of diferent features in generating exercise recommendations from the MAB trial. Table 1
shows the average absolute SHAP values for the top 10 features:</p>
          <p>Feature
Age
Exercise Frequency
Exercise Duration
Medical History
Preferred Exercise
Weekly Goal
Cardio Preference
Strength Preference
Sex
Race
Start Preference
Exercise Variety
Exercise Location
Exercise Buddy
Coach Appearance</p>
          <p>Age, Exercise Frequency, and Exercise Duration are shown as the most important features across
all three arms. Medical History and Preferred Exercise also have high SHAP values, indicating their
significance in personalizing recommendations. Cardio Preference has a higher SHAP value for the
Cardio arm, while Strength Preference has a higher value for the Strength arm, as would be expected.
Some features, like Race and Coach Appearance, have lower SHAP values, suggesting they have
less influence on the recommendations. The relative importance of features varies across the three
arms, reflecting how diferent factors may be more or less relevant for diferent types of exercise
recommendations.</p>
        </sec>
        <sec id="sec-3-2-2">
          <title>3.2.2. Recommendation Consistency and Fairness assessment</title>
          <p>To assess the consistency of recommendations across similar user profiles, we calculated the Jaccard
similarity index for recommendations made to users with similar characteristics. For users with matching
Age (±5 years), Sex, and Medical History, the average Jaccard similarity of recommendations was 0.73,
indicating a high degree of consistency while still allowing for personalization.</p>
          <p>
            To ensure the model wasn’t biased against particular demographic groups, we conducted a
fairness assessment using the equal opportunity diference (EOD) metric [
            <xref ref-type="bibr" rid="ref22">22</xref>
            ]. The EOD values for key
demographic features were:
          </p>
          <p>These values suggest relatively low levels of demographic bias in the recommendations, though
there is still room for improvement. The addition of the SHAP-based XAI layer increased the average
recommendation generation time from 12.3 ms to 89.7 ms (± 5.2 ms). This increase in latency is
considered acceptable given the valuable insights provided by the explanations.</p>
        </sec>
        <sec id="sec-3-2-3">
          <title>3.2.3. Example explanation</title>
          <p>Here is a 62-year-old male user with hypertension, preferring strength training 7 times a week for
90-105 minutes.</p>
          <p>Recommendations provided to user: A mix of moderate-intensity strength training and low-impact
cardio exercises.</p>
          <p>XAI rationale visible to user: "Exercise recommended for you, considering your age of 62 years
and medical history of hypertension, where staying active with combination of cardio and strength
training for 30-45 minutes a day, 4-5 days a week, is ideal. This follows the exercise guidelines to
manage hypertension, keeping you healthy and strong."</p>
          <p>The top 3 features influencing this recommendation by recommender were:
1. Age (SHAP value: +0.42): Increased the likelihood of recommending low-impact exercises
2. Medical History: Hypertension (SHAP value: -0.38): Decreased the intensity of recommended
strength training
3. Exercise Frequency (SHAP value: +0.35): Increased the variety of recommended exercises</p>
        </sec>
      </sec>
    </sec>
    <sec id="sec-4">
      <title>4. Future work</title>
      <p>While these quantitative results provide valuable insights into the functioning of our Recommender
System and the XAI layer, future work will include qualitative studies to evaluate user understanding
and satisfaction with the explanations provided. We plan to conduct:
1. Semi-structured interviews with a diverse group of users to gather in-depth feedback on the
clarity and usefulness of the explanations.
2. A longitudinal study to assess how the presence of explanations afects user adherence to
recommended exercise routines over time
3. A comparative study between diferent explanation formats (e.g., natural language vs. visual
representations) to determine the most efective way to communicate the reasoning behind
recommendations.</p>
      <p>Future iterations of this system will incorporate additional factors such as exercise intensity and
explore more sophisticated feature interactions, further enhancing the personalization and efectiveness
of the recommendations. Planned qualitative studies, including semi-structured interviews and
longitudinal assessments, will provide crucial insights into user understanding, satisfaction, and long-term
adherence to recommended exercise routines.</p>
      <p>As we move forward with testing the system on both healthy individuals and those with cardiovascular
conditions, we aim to validate its efectiveness in real-world scenarios.</p>
    </sec>
    <sec id="sec-5">
      <title>5. Conclusion</title>
      <p>
        This study introduces a novel recommendation system designed to address key challenges in personalized
exercise interventions. By using DQN with MAB algorithm, we solve the user cold start problem [
        <xref ref-type="bibr" rid="ref4 ref5 ref6">6, 4, 5</xref>
        ]
and improve the interpretability of deep learning models, ensuring exercise recommendations are
personalized and aligned with medical advice.
      </p>
      <p>The implementation of this recommender within a mobile application can not only promote regular
physical activity but can also help users build lasting exercise habits in a mobile-driven world. With an
average recommendation generation time including the XAI layer being 89.7 ms (± 5.2 ms), our system
is both computationally eficient and practical for real-time use.</p>
      <p>Our approach represents a significant step forward in digital health, combining advanced ML with
XAI layer to promote guideline-based physical activity. By tackling the cold start problem and enhancing
algorithm transparency, this system has the potential to foster lasting behavior change and improve
public health.</p>
    </sec>
    <sec id="sec-6">
      <title>6. Disclosure</title>
      <p>Parvati Naliyatthaliyazchayil hereby discloses that she has volunteered at Indiana University and is
currently employed by ConcertAI. This disclosure applies solely to Parvati Naliyatthaliyazchayil and
does not extend to any of the other authors of this paper.</p>
    </sec>
  </body>
  <back>
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