Is There A Difference In Strength, Flexibility, Range Of Motion Between Postpartum And Nulliparous Runners?

Abstract

Research has shown that women are returning to sport as soon as two weeks after birth with most resuming running by two months postpartum. There are significant musculoskeletal and physiologic changes during pregnancy as well as the effects of childbirth that a postpartum runner to recover from to return to running. Research on returning to running guidelines are nonexistent in the postpartum population. PURPOSE: To investigate the differences in strength, range of motion (ROM), and, flexibility between postpartum runners (PP) and nulliparous controls (NC). METHODS: Healthy postpartum (up to 3 years) and nulliparous runners were recruited from local running groups. Three trials of strength, ROM and flexibility of the hip, knee and ankle were collected using a hand held dynamometer, inclinometer or goniometer respectively and then averaged. An independent samples t-test was performed to compare groups. RESULTS: 28 runners participated (14 PP, 14 NC) and were matched for BMI (24.2 kg/sq.m). There were no significant differences in strength of the hip, knee and ankle between the groups. Right and left ankle dorsiflexion was significantly greater in PP group (Right Soleus: PP, 10.33±3.9cm; NC, 6.75±2.68cm; p=0.01; Left soleus: PP, 11.32±3.8cm; NC, 7.34±2.74cm; p=0.004; Right Gastrocnemius: PP, 7.95±2.74°; NC, 4.67±4.59°; p=0.032; Left Gastrocnemius: PP, 8.48±3.39°; NC, 4.5±5.23°; p=0.026). Knee and Hip ROM were not significantly different between the groups. CONCLUSION: The current study shows that postpartum runners have significantly more dorsiflexion ROM than controls. When breastfeeding, hormones that influence elasticity like prolactin are still present in the body which may be allowing for the postpartum women to have significantly more ROM than nulliparous controls. Future studies should investigate the effect of breastfeeding duration on range of motion in runners as well as if while breastfeeding return to running guidelines should be different than women that cease breastfeeding at different stages.