Abstract
BackgroundStudies have recently focused on the effect of running a mountain ultra-marathon (MUM) and their results show muscular inflammation, damage and force loss. However, the link between peripheral oedema and muscle force loss is not really established. We tested the hypothesis that, after a MUM, lower leg muscles’ swelling could be associated with muscle force loss. The knee extensor (KE) and the plantar flexor (PF) muscles’ contractile function was measured by supramaximal electrical stimulations, potentiated low- and high-frequency doublets (PS10 and PS100) of the KE and the PF were measured by transcutaneous electrical nerve stimulation and bioimpedance was used to assess body composition in the runners (n = 11) before (Pre) and after (Post) the MUM and compared with the controls (n = 8).ResultsThe maximal voluntary contraction of the KE and the PF significantly decreased by 20 % Post-MUM in the runners. Hydration of the non-fat mass (NF-Hyd) and extracellular water volume (Ve) were increased by 12 % Post-MUM (p < 0.001) in the runners. Calf circumference (+2 %, p < 0.05) was also increased. Significant relationships were found for percentage increases in Ve and NF-Hyd with percentage decrease in PS10 of the PF (r = −0.68 and r = −0.70, p < 0.05) and with percentage increase of calf circumference (r = 0.72 and r = 0.73, p < 0.05) in the runners.ConclusionsThe present study suggests that increases in circumference and in hydric volume are associated to contractile impairment in the calf in ultra-marathon runners.
Highlights
Studies have recently focused on the effect of running a mountain ultra-marathon (MUM) and their results show muscular inflammation, damage and force loss
Body composition parameters The circumference of the calf was increased in the runners after the MUM (Post)-MUM (Pre vs. Post: 37.3 ± 0.7 vs. 38.1 ± 0.6 cm, p < 0.05), but not in the control group (37.8 ± 0.8 vs. 38.0 ± 0.9 cm, ns)
All the other bioimpedance parameters were significantly altered after the MUM in runners (Table 2)
Summary
Studies have recently focused on the effect of running a mountain ultra-marathon (MUM) and their results show muscular inflammation, damage and force loss. One study reported a muscle force impairment in healthy volunteers after damaging exercise and a second decrease in muscle strength after 2 days [11] This second decrease in the maximal voluntary force of the plantar flexors was not related to electromyographic activity reduction but to an increase in muscle thickness, suggesting a direct impact of muscle volume expansion and muscular strength loss. This last finding is important because increased volume of an athlete’s body extremities or limbs and decreased muscle force loss have been reported after ultra-running events. Muscle volume expansion (i.e. in the muscles of the lower leg) appears to be related potentially to muscle force loss in athletes after MUMs
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