Research Project Doctoral Candidate 03

Can the structure of behavioural and physiological variability predict the training outcomes? – multidimensional assessment and intervention in older adults

 

Fellow

Victoria Trifonova

 

Host Institution

Aix-Marseille University, Institute of Movement Science

 

Supervisors

Dr. Rita Sleimen-Malkoun

Prof. Dr. Jean-Jacques Temprado

 

Project description

Rooted in the Dynamic Systems Approach, this project views aging as an emergent, system-wide process characterized by structural and functional changes, moderated by both external and internal factors. By prioritizing system-level markers (e.g., motor variability, physiological signal fluctuations), we aim to decode the aging system’s adaptive capacity and functional state, and provide best practice guidelines for interpreting variability in geriatric assessment and training, thereby bridging research and clinical practice.

Specifically, the project aims to:

1.    Determine the most adequate and clinically relevant methods for quantifying neuro-behavioural variability

2.     Characterize optimal and impaired ageing by comparing subgroups with different functional states (Young, Master Athletes, Older Adults, Sedentary Older Adults, Older adults with cognitive impairment)

3. Link age-related changes in variability to the performance in routinely used functional tests (e.g., handgrip strength, walking speed, cognitive tests), and to behavioural adaptation capacities to task constraints.

4.     Examine the role of behavioural variability in predicting the outcomes of training intervention.

To achieve these goals, force control tasks will be used as a functionally and clinically relevant model system for geriatric assessment and intervention. Data acquisition will include behavioural (kinetic and kinematic) and neurophysiological (EMG) measures, with data analysis including nonlinear methods (e.g., entropy, self-similarity, regularity metrics). Beyond contributing to scientific literature, this project will deliver a methodological handbook for interpreting variability metrics in research and clinical contexts, as well as an open-access toolbox that simplifies data analysis for scientists and clinicians.

 

(Planned) Secondments

Stade Marseillais Université Club

University of Münster

 

Project Updates

May 2026

I am currently finalising my first publication on age-related changes in fine motor control, specifically examining how aging alters coordination during a rhythmic force-modulation task. We assessed coordination through the lens of complexity - capturing the temporal structure of motor variability via multiscale entropy - alongside magnitude-based measures such as standard deviation. By comparing multiple measures characterising force–target coordination, we showed that these measures not only follow the expected Loss of Complexity pattern with aging, but also discriminate between age groups more effectively than the produced force signal alone.

In addition, I am working closely with a team of developers to build the task interface for my first experiment, which involves a rhythmic force-modulation task performed either via manual pinch grip (force control) or postural sway (posture control), with simultaneous electromyographic (EMG) recordings from target muscles. The force control task with EMG synchronisation is currently being piloted, while the posture control task is still under development. Both of these works align with the broader goals of the TReND network to advance the understanding of movement variability, and are conducted under the supervision of Dr. Rita Sleimen-Malkoun and Prof. Jean-Jacques Temprado at Aix-Marseille University.

June 2025

Currently, a data analysis towards the first project aim -determining the most sensitive methods for studying age-related changes - is conducted.