A simple improvement might enhance the exercise regime: committing to performing activities at the same time each day.
A study in mice suggests several benefits arise from maintaining a regular exercise rhythm.
While a central body clock exists in the brain (in the suprachiasmatic nucleus, or SCN), other, more localized body clocks are also present. According to research led by the University of Manchester in the UK, exercise can reset the local body clocks in the joints and spine.
If this reset occurs at the same time each day, these local clocks can better synchronize with the SCN clock, as discovered by the research team. Previous studies have shown that clocks in peripheral tissues that are out of sync can increase the risk of issues such as diabetes and cardiovascular disease.
“Results showed that physical activities in the morning, associated with daily patterns of sleep/wake cycle, convey timing information from the light-sensitive central clock in the brain to the weight-bearing skeletal tissues. In effect, it’s telling the skeletal system it’s time to wake up.”
Qing-Jun Meng, chronobiologist at the University of Manchester.
A genetic reporting technique was utilized by researchers to monitor the clocks in the cartilage (joints), intervertebral discs (spine), and brains of transgenic mice, while exercise was performed on treadmills at different times. Cartilage tissue samples taken from the mice were also studied for their osmotic responses.
These areas – the joints and spine – are particularly involved in exercise, and water is pressed out of them throughout the day (making individuals slightly shorter). This process partly resets the localized body clocks on a daily basis.
It was found that activity added to this process of osmolarity (water reduction), further resetting these clocks and – if done on a consistent schedule – improving the timing links between the clocks in the body. These results still need to be confirmed in humans, but similar effects are likely at play.
The health of bones and joints impacts everything from sports performance to the likelihood of injuries or conditions such as arthritis. The risk of injury may be increased in athletes traveling through time zones, the researchers suggest.
Clock syncing was also observed in older animals – indicating that even those in later life who might only do some brisk walking each day, doing it at the same consistent time, is likely to be helpful.
“Not only has it been identified that misalignment between cartilage and intervertebral disc clocks and the central clock in the brain can occur through exercising at an inappropriate time. The mechanism by which this happens has been found, and skeletal clocks can resynchronize to daily patterns of physical activity.”
Qing-Jun Meng
https://www.nature.com/articles/s41467-023-42056-1
Abstract
Daily rhythms in mammalian behaviour and physiology are generated by a multi-oscillator circadian system entrained through environmental cues (e.g. light and feeding). The presence of tissue niche-dependent physiological time cues has been proposed, allowing tissues the ability of circadian phase adjustment based on local signals. However, to date, such stimuli have remained elusive. Here we show that daily patterns of mechanical loading and associated osmotic challenge within physiological ranges reset circadian clock phase and amplitude in cartilage and intervertebral disc tissues in vivo and in tissue explant cultures. Hyperosmolarity (but not hypo-osmolarity) resets clocks in young and ageing skeletal tissues and induce genome-wide expression of rhythmic genes in cells. Mechanistically, RNAseq and biochemical analysis revealed the PLD2-mTORC2-AKT-GSK3β axis as a convergent pathway for both in vivo loading and hyperosmolarity-induced clock changes. These results reveal diurnal patterns of mechanical loading and consequent daily oscillations in osmolarity as a bona fide tissue niche-specific time cue to maintain skeletal circadian rhythms in sync.
