High-level athletes: could a simple smartwatch be the solution to stress management?

Finding and interpreting appropriate health indicators

Smartphones and smartwatches provide athletes with a wide variety of health indicators, such as their heart rate at rest and after exercise, calorie expenditure and sleep analysis. But other than detecting an increased heart rate or a bad night’s sleep, can they really help to improve the health of athletes? Taous-Meriem Laleg, head of the BOOST Project Team (Bio-informed mOnitoring & Optimization for enhanced Sport & healTh) at the Inria Saclay Centre, certainly hopes so. 

“Connected objects provide us with a vast amount of data, but which we are incapable of interpreting efficiently”, the researcher explains. “Either because the data is irrelevant, or because signal processing has to be used to extract a useful indicator.” 

For example, smartwatches monitor heart rate using the photoplethysmography (PPG) technique to measure variations in blood volume. “But could these signals also be associated with blood pressure or stress levels?”, the scientist wonders. “And if we use artificial intelligence to combine them with other data, can we extract information that’s even more relevant?”

Combing physiology, signal processing and modelling

Taous-Meriem Lang began exploring these questions in late 2021, when Inria suggested she set up a project team. The researcher called upon her colleagues from the CIAMS laboratory (Complexity, Innovation and Motor & Sports Activities) at Paris-Saclay University, with whom she had already worked. “I had previously applied signal processing and modelling tools to the cardiovascular system, and they study the neuroscience, perception, physiology and mobility aid aspects... So we decided to combine all this expertise for the benefit of athletes’ health.” Together, they spent the years that followed defining the scope of their future collaboration, set up the partnership between Inria and Paris-Saclay University, launched a first joint thesis... And finally, BOOST was officially created in January 2025. 

The team has set itself the target of identifying signals that are easily accessible, in particular by smart devices (PPG for example), and developing algorithms that can interpret them in order to extract useful information for the assessment of professional athletes’ state of health.

Day-to-day monitoring of the mental health of athletes

The scientists decided to begin by focussing on mental health, based on the appreciation of stress levels. This is a key issue for high-level athletes, as stress can have a negative impact on their performance. Indeed, a study conducted in 2024 by the FondaMental Foundation shows that 24% of them suffer from anxiety and 44% from sleep disorders. 

“Nowadays, athletes do try to assess their stress levels, using questionnaires for example, but these reflect perceived stress only. If we can develop tools that quantify stress, this would be a complementary and beneficial approach.” 

So what’s the first step? To establish a network protocol to collect health data in various stressful situations. Three experiments have been finalised: in the first, the participant spends 14 minutes on an exercise bike; in the second, they plunge a hand into icy water for 3 minutes; and in the third, named ‘Sing a Song Stress Test’, the participant is suddenly asked to start singing out loud. “We know that each of these situations will generate physical or mental stress”, explains the head of the team. “Therefore, we will do our best to record this stress in the form of electroencephalogram (EEG) and electrocardiogram (ECG) signals, as well as blood pressure and PPG variations. We will then develop a mathematical model to compare the data and try to understand the interplay between these different signals and identify reliable stress indicators.”

A first publication and a future partnership

The team has already obtained its first results which have been published: using an existing database, they reveal that the presence or absence of stress can indeed be established by combining EEG and ECG signals. The researchers intend to refine and qualify these observations in order to accurately assess levels of physiological stress. To this end, the team have begun discussions with INSEP (French National Institute of Sport, Expertise and Performance) in order to extend their experiments (currently conducted on CIAMS interns) to high-level athletes. 

Eventually, the algorithms developed through this research could be incorporated into rings that would be able to perform PPG tests and would therefore be compatible with physical exercise. Training routines and schedules could then be adjusted to accommodate stress levels measured in this way, in order to safeguard the athlete’s physical performance and mental health. 

Research that can be applied to other health matters

In the longer term, the researchers actually intend to work on biofeedback quality: how can the information produced be presented to the user? What measures can be suggested to users in the interests of their health and performance? The team also want this type of research to be of benefit to the physical health of athletes, for example by preventing fatigue and injury on the basis of other easily accessible indicators, such as heart rate variability, PPG, accelerometer, etc. 

At the same time, other BOOST projects are underway in various medical fields. One of them, in association with AP-HP, aims to detect vulnerable carotid plaques using carotid imagery, particularly in patients showing no symptoms. Objective: to provide surgeons with a decision support tool regarding the pertinence of operating. Another project concerns the analysis of arterial rigidity. “It has been established that this is a risk factor in cardiovascular disease, but today there is no reliable, easy and non-invasive way to evaluate it”, explains Taous-Meriem Laleg. “Again, could PPG tests be of help?” Lastly, a third project focuses on the modelling and monitoring of muscle co-contraction, to facilitate exoskeleton-based mobility aid. 

What is the team’s strength in meeting these challenges? “We are developing our own signal processing tools and mathematical models, particularly adapted to biomedical data”, replies the head of the team. A method that is getting results.

Find out more

• High-level athletes also concerned by mental health issues, according to a study, France Inter, 17/9/2024.
• How do athletes manage stress before and during a competition? Le Progrès, 23/6/2024.
• Digital technology and athletic performance: how research helps push the boundaries of athletes, Inria 17/4/2024
• Innovation revolutionising sports, CNRS, 18/7/2024.
• Sports: connected objects, valuable tools for performance, Sciences et Avenir, 3/11/2020.