High-Intensity Exercise May Be Key to Bone Health

When it comes to exercising for bone health, a study published in Sports Medicine – Open suggests the intensity of a workout may matter more than the type or the duration.

A Closer Look at Exercise and Bone Biomarkers

Investigators at Semmelweis University in Hungary conducted a systematic review and meta-analysis pooling data from 24 randomized controlled trials involving 1,238 healthy adults. Rather than measuring bone mineral density directly, which typically takes months or years to shift, the team looked at blood biomarkers that reflect active bone formation, particularly a protein called osteocalcin. These biomarkers can pick up on the effects of exercise within just a few weeks, offering a much earlier read on whether a given workout is stimulating new bone growth.

"What makes our study unique is that we examined not only the type of exercise, whether endurance, resistance or combined training, but also exercise intensity, frequency and duration," said Péter Ferdinandy, M.D., Ph.D., vice-rector for science and innovations at Semmelweis University and senior author of the study. "Our goal was to determine which forms of exercise stimulate bone metabolism most effectively and which appear to be less beneficial from this perspective."

Intensity, Not Category, Made the Difference

Across the pooled data, only high-intensity training significantly raised osteocalcin levels. Low- and high-intensity endurance training, power training and mixed training all failed to produce a significant change in this marker, regardless of how long or how often participants trained. High-intensity training was also linked to a significant drop in body mass index, while other training types showed no meaningful effect on bone mineral density.

In practical terms, the investigators found that recreational sports involving explosive, multidirectional movement, like football and handball, were associated with increases of up to 45% to 46% in bone-formation markers. Walking, step aerobics and traditional gym-based resistance training were generally far less effective by comparison.

"The most surprising finding was that resistance training did not produce a significant effect on markers of bone metabolism, even though several professional guidelines recommend this type of exercise for maintaining bone health," said Viktória Barna, a Ph.D. student at Semmelweis University and the study's first author. "Likewise, low- or moderate-intensity endurance exercise, such as walking or jogging, showed no meaningful long-term effect."

What This Doesn't Mean

Barna and her colleagues are careful to note that this doesn't make walking or lighter activity pointless. Lower-intensity exercise carries well-documented health benefits of its own. But if the specific goal is strengthening bone, the findings suggest the body may need a more forceful mechanical stimulus than walking or standard resistance training typically provides.

"According to the World Health Organization, regular physical activity offers numerous health benefits. However, our findings suggest that low-intensity exercise alone is not sufficient to stimulate bone metabolism," said Nóra Sydó, M.D., Ph.D., a clinical specialist and study coauthor. "High-intensity exercise may trigger early beneficial changes in bone formation, potentially helping to slow bone loss and support healthy aging."

A Note Before Ramping Up Intensity

The investigators caution against jumping into high-intensity training abruptly or without preparation, particularly for people with cardiovascular, musculoskeletal or metabolic conditions, or those already living with osteoporosis. Anyone considering a more demanding training program should check with a physician, primary care provider or sports medicine specialist first, to make sure the activity and its intensity are appropriate for their individual health.

The investigators say their findings could help inform future exercise guidelines aimed at preserving bone health and preventing osteoporosis as people age.