Cardiorespiratory fitness and arm bone mineral health in young males with spinal cord injury: the mediator role of lean mass |
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| Authors: | Irene Rodríguez-Gómez Soraya Martín-Manjarrés María Martín-García Sara Vila-Maldonado Ángel Gil-Agudo Luis M Alegre |
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| Institution: | 1. GENUD Toledo Research Group, Universidad de Castilla-La Mancha, Toledo, Spain;2. CIBER of Frailty and Healthy Aging (CIBERFES), Madrid, Spain;3. Department of Physical Medicine and Rehabilitation, National Hospital for Paraplegics. SESCAM, Toledo, Spain;4. Biomechanics and Technical Aids Unit, Department of Physical Medicine and Rehabilitation, National Hospital for Spinal Cord Injury. SESCAM, Toledo, Spain |
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| Abstract: | Spinal cord injury (SCI) derives in loss of bone mineral content (BMC) and bone mineral density (BMD). However, physical activity is an important determinant in bone mass acquisition, which is partially mediated through the lean mass (LM). The aim was to examine the effect of cardiorespiratory fitness (CRF) on BMD and BMC arms of adult males with SCI and able-bodied controls using the arm LM as a mediator variable. Thirty able-bodied men and thirty men with SCI participated. BMC and BMD were analysed by DXA, and indirect calorimetry was used to calculate VO2peak during a progressive arm-cranking test. When groups were divided by the amount of LM, the subgroup with highest LM had significantly higher arm BMC compared to the lowest LM subgroup (p ≤ 0.05) in both SCI and able-bodied groups. Moreover, same differences were found when confidence intervals were analysed. Only in the SCI group, arm LM mediated the relationship between bone mass and CRF at 30.9%, as indicated by the Sobel test (z = 2.17 and z = 2.04 for BMC and BMD, respectively). In conclusion, LM mediates the indirect association between CRF and bone health, specifically in the arms. This finding highlights the importance of having an adequate CRF for the maintenance of good bone health in SCI men. |
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| Keywords: | Bone mineral density dual energy X-ray absorptiometry physical activity upper limbs VO2peak |
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