Health UK (Commonwealth Union) – A study conducted by scientists at the University of Manchester suggests that maintaining consistent daily patterns of exercise and rest can synchronize local body clocks associated with joints and the spine with the central brain clock. Published in Nature Communications recently, the research, conducted on mice, proposes potential benefits for skeletal health, improved athletic performance, and injury prevention. The scientists posit that human cartilage and intervertebral discs, given their similar physiological properties, are likely to respond in a comparable manner.
The study also draws attention to an observation made 300 years ago by Reverend Mr. Wasse to Dr. Mead, highlighting the difference in human body height between morning and night. Reverend Wasse noted an increase in height after a good night’s sleep, as soldiers discharged from the army were reportedly over half an inch taller.
Daily rhythms in mammalian behavior and physiology are regulated by a circadian system influenced by environmental cues like light and feeding. The research underscores the importance of alignment between the central body clock in the brain and the clocks in other organs, such as joint cartilage, which has no nerve or blood supply. Such alignment is crucial to reducing the risk of pathology and diseases like diabetes and cardiovascular disease.
Funded by consecutive grants from the Medical Research Council and Versus Arthritis, the study, led by Professor Qing-Jun Meng, a senior author and body clock expert at the University of Manchester, not only identifies the potential misalignment between cartilage and intervertebral disc clocks and the central brain clock due to exercising at inappropriate times but also reveals the mechanism behind this phenomenon. Moreover, it demonstrates that skeletal clocks can resynchronize with daily patterns of physical activity.
“Our earlier work discovered internal body clocks in intervertebral discs and cartilage that dampen with ageing. Importantly, healthy cartilage and intervertebral discs have no nerves and no blood supply, so until now it was not clear how their internal clocks synchronise with the brain.”
Professor Judith Hoyland, who is a senior author and spine/intervertebral disc expert as well from The University of Manchester says “Among the many health challenges, the age-related musculoskeletal decline – and its adverse consequences -is a major burden to individuals.
“Loss of bone density, degraded articular cartilage and degeneration of the intervertebral discs are primary features of the ageing skeleton, all of which can contribute to pain and loss of mobility.
“Importantly, we have identified a new clock mechanism underlying skeletal ageing, which could have far-reaching impacts on understanding frailty and designing more efficient treatment timing of exercise and physiotherapy to maintain good skeletal health and mobility.”
Dr. Michal Dudek, the primary author from The University of Manchester, indicated that throughout the day, as we stand and move, water is squeezed out of the intervertebral discs in our spine and the cartilage in hips and knees. This process, as noted by Reverend Mr. Wasse 300 years ago, makes us slightly shorter by the end of the day.
Dr. Dudek also indicated that what Reverend Wasse was not able to realize, is that this leads to an increase in osmolarity within the tissue. The same amount of minerals is now dissolved in less water, causing the concentration to rise. Cells detect this change in osmolarity and synchronize the clocks within these skeletal tissues.
Dr. Dudek further pointed out that the water is replenished at night during rest, reducing osmolarity. Interestingly, this change in direction has no effect on the clock.
In their study, the scientists focused on mice subjected to daily exercise on a treadmill during their resting period to observe the impact on the clocks in the cartilage, intervertebral disc, and the brain. To validate their findings, the researchers compressed mouse intervertebral discs or cartilage explants in the laboratory and exposed them to higher osmolarity culture medium within a normal physiological range. In both cases, a similar clock synchronizing effect was observed.
