Med Sci Sports Exerc. 2022 Oct 12. doi: 10.1249/MSS.0000000000003062. Online ahead of print.
ABSTRACT
BACKGROUND: High impact loads have been linked with running injuries. Fatigue has been proposed to increase impact loads, but this relationship has not been rigorously examined, including the associated role of muscle strength, power, and endurance.
PURPOSE: To investigate the effect of fatigue on impact loading in runners, and the role of muscle function in mediating changes in impact loading with fatigue.
METHODS: Twenty-eight trained endurance runners performed a fixed-intensity time to exhaustion test at 85% of V̇O2max. Tibial accelerations were measured using leg-mounted inertial measurement units (IMUs) and sampled every minute until volitional exhaustion. Tests of lower-limb muscle strength, power, and endurance included maximal isometric strength (soleus, knee extensors, knee flexors), single leg hop for distance, and the one leg rise test. Changes in peak axial tibial acceleration (PTA, g) were compared between time-points throughout the run (0, 25, 50, 75 and 100%). Associations between the change in PTA and lower limb muscle function tests were assessed (Spearman’s rho [rs]).
RESULTS: Peak tibial acceleration increased over the duration of the fatiguing run. Compared to baseline (0%) (9.1 g SD 1.6), there was a significant increase at 75% (9.9 g SD 1.7., p = 0.001) and 100% (10.1 g SD 1.8, p < 0.001), with no change at 25% (9.6 g SD 1.6, p = 0.142) or 50% (9.7 g SD 1.7, p = 0.053). Relationships between change in peak tibial acceleration and muscle function tests were weak and not statistically significant (rs = -0.153 to 0.142, all p > 0.05).
CONCLUSIONS: Peak axial tibial acceleration increased throughout a fixed-intensity run to exhaustion. The change in PTA was not related to performance in lower limb muscle function tests.
PMID:36251400 | DOI:10.1249/MSS.0000000000003062
