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J Athl Train. 2015 Feb;50(2):117-25. doi: 10.4085/1062-6050-49.3.90. Epub 2014 Dec 22.

High-intensity running and plantar-flexor fatigability and plantar-pressure distribution in adolescent runners.

Author information

1
Aspire Health Centre, National Sports Medicine Programme (NSMP), Doha, Qatar;

Abstract

CONTEXT:

Fatigue-induced alterations in foot mechanics may lead to structural overload and injury.

OBJECTIVES:

To investigate how a high-intensity running exercise to exhaustion modifies ankle plantar-flexor and dorsiflexor strength and fatigability, as well as plantar-pressure distribution in adolescent runners.

DESIGN:

Controlled laboratory study.

SETTING:

Academy research laboratory.

PATIENTS OR OTHER PARTICIPANTS:

Eleven male adolescent distance runners (age = 16.9 ± 2.0 years, height = 170.6 ± 10.9 cm, mass = 54.6 ± 8.6 kg) were tested.

INTERVENTION(S):

All participants performed an exhausting run on a treadmill. An isokinetic plantar-flexor and dorsiflexor maximal-strength test and a fatigue test were performed before and after the exhausting run. Plantar-pressure distribution was assessed at the beginning and end of the exhausting run.

MAIN OUTCOME MEASURE(S):

We recorded plantar-flexor and dorsiflexor peak torques and calculated the fatigue index. Plantar-pressure measurements were recorded 1 minute after the start of the run and before exhaustion. Plantar variables (ie, mean area, contact time, mean pressure, relative load) were determined for 9 selected regions.

RESULTS:

Isokinetic peak torques were similar before and after the run in both muscle groups, whereas the fatigue index increased in plantar flexion (28.1%; P = .01) but not in dorsiflexion. For the whole foot, mean pressure decreased from 1 minute to the end (-3.4%; P = .003); however, mean area (9.5%; P = .005) and relative load (7.2%; P = .009) increased under the medial midfoot, and contact time increased under the central forefoot (8.3%; P = .01) and the lesser toes (8.9%; P = .008).

CONCLUSIONS:

Fatigue resistance in the plantar flexors declined after a high-intensity running bout performed by adolescent male distance runners. This phenomenon was associated with increased loading under the medial arch in the fatigued state but without any excessive pronation.

KEYWORDS:

ankle; isokinetic exercise; medial longitudinal arch; pronation

PMID:
25531143
PMCID:
PMC4495434
DOI:
10.4085/1062-6050-49.3.90
[Indexed for MEDLINE]
Free PMC Article

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