Running may be better than cycling for long-term bone health
Exercise that puts greater strain on bones, like running, may improve
long-term bone health more effectively than non weight-bearing
activities like cycling, conclude the authors of a new study measuring
the hormones of mountain ultra-marathon runners. The results of the
study are presented at the European Congress of Endocrinology.
Previous research from the Istituto Ortopedico Galeazzi in Milan
found that cyclists racing in ultra-endurance conditions suffered
chronic bone resorption - where calcium from bone is released into the
blood stream, weakening bones. In this study, the same group set to find
out whether a similar group of elite athletes - mountain ultra-marathon
runners - had the same response.
researchers measured two vital bone constituents as well as hormones
associated with energy regulation. Osteocalcin and P1NP are two proteins
associated with bone formation and their levels in blood are an
indicator of bone health. Glucagon, leptin and insulin are hormones
involved in regulating metabolism and indicate the body's energy needs.
Increasing glucagon levels indicate an energy demand, whilst increasing
insulin and leptin levels indicate adequate or excessive energy levels.
The researchers measured these three hormones as well as levels of
osteocalcin and P1NP in 17 trained runners before and after a 65-km
mountain ultramarathon run and compared it to the hormones and bone
constituents of twelve adults of the same age who didn't run the race
but did low to moderate physical exercise.
Compared to the control group, ultramarathon runners had higher
levels of glucagon and lower levels of leptin and insulin when finishing
The falling levels of insulin within this group were linked to
similarly falling levels of both osteocalcin and P1NP - suggesting that
athletes may be diverting energy from bone formation to power the
high-energy demands of their metabolism. However, ultramarathon runners
had higher P1NP levels at rest compared to controls, suggesting that
they may divert energy from bones during racing but have a net gain in
bone health in the long-term.
"The every-day man and woman need to exercise moderately to maintain
health", said Dr Giovanni Lombardi, lead author of the study. "However,
our findings suggest that those at risk of weaker bones might want to
take up running rather than swimming or cycling".
One theory that could explain the effect of different exercises on
bone formation is the role of osteocalcin, explains Dr Lombardi.
"Previous studies have shown that osteocalcin communicates with beta
cells in the pancreas, which regulate the body's glucose metabolism", he
said. "Because running exerts a higher physical load on bone than
swimming or cycling, it could be that these forces stimulate bone tissue
to signal to the pancreas to help meet its energy needs in the