This study explored how patterns of daily activity and rest—referred to as rest-activity rhythms (RARs)—are related to cardiorespiratory fitness and walking energetics in older adults. Given the known declines in physical capacity with aging, our aim was to understand whether behavioural rhythms play a role in maintaining physical function.
Methods
Data were collected from 799 participants (average of 76 years) as part of the Study of Muscle, Mobility and Aging (SOMMA) consortium. Participants wore wrist actigraphy devices for up to 7 days to capture continuous movement patterns. From these data, rhythm metrics were computed, including relative amplitude (difference between daytime and nighttime activity), intra-daily variability (how fragmented activity was), and inter-daily stability (consistency of rhythms across days). Cardiorespiratory fitness (VO₂peak) was assessed via treadmill testing, and walking energetics (oxygen consumption per distance) were measured under controlled walking conditions. Statistical models adjusted for age, sex, body composition, physical activity, comorbidities, and sleep duration.
Key Findings
- Higher relative amplitude and better rhythm stability were associated with higher VO₂peak.
- Lower rhythm fragmentation (less intra-daily variability) was linked to more efficient walking energetics.
- These associations were independent of overall physical activity levels and sleep characteristics, indicating that rhythm regularity itself may be key.
- The findings held across multiple models with rigorous adjustment for confounding factors.
Consistent daily rest-activity rhythms are linked to better cardiorespiratory fitness and more efficient walking in older adults. This supports the idea that maintaining stable daily behavioural rhythms—beyond just being active—may contribute to healthier aging. Interventions targeting rhythm regulation (like light exposure or exercise routines) could potentially support physical function later in life.
Erickson ML, Blackwell TL, Garcia RE, Mau T, Cawthon PM, Cummings SR, Farsijani S, Sparks LM, Noone J, Glynn NW, Newman AB, Esser KA. Rest Activity Rhythms and their Association with Cardiorespiratory Fitness and Walking Energetics in Older Adults: Study of Muscle, Mobility and Aging. Med Sci Sports Exerc. 2025 Apr 18. DOI: 10.1249/MSS.0000000000003730
John Noone, PhD is an Assistant Professor in Sport & Exercise Physiology in the Department of Physical Education and Sport Sciences, University of Limerick. Contact: Email: john.noone@ul.ie UL Pure: John Noone – University of Limerick X:@JohnNoone4
ResearchGate: https://www.researchgate.net/profile/John-Noone?ev=hdr_xprf
ORCID: https://orcid.org/0000-0002-5733-4816
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