Bone marrow fat and physical activity in humans

Bone marrow fat (BMF) is an adipose tissue depotnegatively correlated with bone mineral density andhematopoiesis. The influence of physical activity (PA)on BMF is still poorly understood. The aim of this studywas to systematically analyze literature investigating theassociation between PA/exercise and BMF in humans. Theliterature search (MEDLINE, Scopus, SPORTDiscus, Webof Science) yielded 16 (9 cross-sectional/7 intervention)studies exploring: the relationship between practicingsports and BMF in athletes; PA and BMF in the generalpopulation; the effect of exercise during/reambulation afterprolonged bed rest on BMF. Athletes practicing high-impactsports had a lower BMF than non-athletes in load-bearingskeletal regions (lumbar vertebra, mid-tibia, femoral neck).Active non-athletes had a lower BMF than inactive persons.High-volume weight-bearing activities were associated witha more significant BMF decrease. The adipogenic effectof estrogen deficiency on BMF was observed in oligoamenorrheicathletes. The impact of reambulation afterprolonged bed rest is still inconclusive. Based on the resultsof the studies, high-impact PA is associated with lowerBMF in load-bearing skeletal regions. There is a lack ofrandomized controlled trials and a standardized diagnosticmethodology. Future studies should include differentpopulations, larger samples, and longer interventions, andanalyze different skeletal regions.