Limits...
Effect of the Fatigue Induced by a 110-km Ultramarathon on Tibial Impact Acceleration and Lower Leg Kinematics.

Giandolini M, Gimenez P, Temesi J, Arnal PJ, Martin V, Rupp T, Morin JB, Samozino P, Millet GY - PLoS ONE (2016)

Bottom Line: Among biomechanical variables, step frequency increased by ~2.7% and the ankle range of motion decreased by ~4.1% post-MUM.Runners adopting a non rearfoot strike pre-MUM adopted a less plantarflexed foot strike pattern post-MUM while those adopting a rearfoot strike pre-MUM tended to adopt a less dorsiflexed foot strike pattern post-MUM.This strategy may aim at minimizing the overall load applied to the musculoskeletal system, including impact shock and muscle stretch.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Exercise Physiology (EA4338), University Savoie Mont Blanc, Le Bourget-du-Lac, France.

ABSTRACT
Ultramarathon runners are exposed to a high number of impact shocks and to severe neuromuscular fatigue. Runners may manage mechanical stress and muscle fatigue by changing their running kinematics. Our purposes were to study (i) the effects of a 110-km mountain ultramarathon (MUM) on tibial shock acceleration and lower limb kinematics, and (ii) whether kinematic changes are modulated according to the severity of neuromuscular fatigue. Twenty-three runners participated in the study. Pre- and post-MUM, neuromuscular tests were performed to assess knee extensor (KE) and plantar flexor (PF) central and peripheral fatigue, and a treadmill running bouts was completed during which step frequency, peak acceleration, median frequency and impact frequency content were measured from tibial acceleration, as well as foot-to-treadmill, tibia-to-treadmill, and ankle flexion angles at initial contact, and ankle range of motion using video analysis. Large neuromuscular fatigue, including peripheral changes and deficits in voluntary activation, was observed in KE and PF. MVC decrements of ~35% for KE and of ~28% for PF were noted. Among biomechanical variables, step frequency increased by ~2.7% and the ankle range of motion decreased by ~4.1% post-MUM. Runners adopting a non rearfoot strike pre-MUM adopted a less plantarflexed foot strike pattern post-MUM while those adopting a rearfoot strike pre-MUM tended to adopt a less dorsiflexed foot strike pattern post-MUM. Positive correlations were observed between percent changes in peripheral PF fatigue and the ankle range of motion. Peripheral PF fatigue was also significantly correlated to both percent changes in step frequency and the ankle angle at contact. This study suggests that in a fatigued state, ultratrail runners use compensatory/protective adjustments leading to a flatter foot landing and this is done in a fatigue dose-dependent manner. This strategy may aim at minimizing the overall load applied to the musculoskeletal system, including impact shock and muscle stretch.

Show MeSH

Related in: MedlinePlus

Means (white dots) and standard deviation for impact-related parameters (panel A: PTA, panel B: MDF, panel C: iPSD) pre-MUM and post-MUM, as individual values (gray dots).
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4816299&req=5

pone.0151687.g002: Means (white dots) and standard deviation for impact-related parameters (panel A: PTA, panel B: MDF, panel C: iPSD) pre-MUM and post-MUM, as individual values (gray dots).

Mentions: The subjects completed the race in 19:35:21 ± 4:00:15. No significant changes in PTA, MDF or iPSD were found between pre- and post-MUM (Fig 2). Average values of impact-related and kinematic parameters are reported in Tables 2 and 3, respectively. As shown in individual data presented in Fig 1, large inter-subject variability in changes between pre- and post-MUM was found (i.e. PTA: -1.2 ± 17.0%, MDF: 1.8 ± 10.8%, iPSD: 6.3 ± 28.6%). The kinematic parameter SF increased by 2.7 ± 4.1% (p = 0.013, Fig 3) and ANKrom decreased by -4.1 ± 8.5% (p = 0.024, Fig 3). Other kinematic variables were not altered (ΔFOOT: 0.3 ± 5.3%, ΔANK: -0.2 ± 5.8%, ΔTIB: -0.8 ± 2.2%).


Effect of the Fatigue Induced by a 110-km Ultramarathon on Tibial Impact Acceleration and Lower Leg Kinematics.

Giandolini M, Gimenez P, Temesi J, Arnal PJ, Martin V, Rupp T, Morin JB, Samozino P, Millet GY - PLoS ONE (2016)

Means (white dots) and standard deviation for impact-related parameters (panel A: PTA, panel B: MDF, panel C: iPSD) pre-MUM and post-MUM, as individual values (gray dots).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4816299&req=5

pone.0151687.g002: Means (white dots) and standard deviation for impact-related parameters (panel A: PTA, panel B: MDF, panel C: iPSD) pre-MUM and post-MUM, as individual values (gray dots).
Mentions: The subjects completed the race in 19:35:21 ± 4:00:15. No significant changes in PTA, MDF or iPSD were found between pre- and post-MUM (Fig 2). Average values of impact-related and kinematic parameters are reported in Tables 2 and 3, respectively. As shown in individual data presented in Fig 1, large inter-subject variability in changes between pre- and post-MUM was found (i.e. PTA: -1.2 ± 17.0%, MDF: 1.8 ± 10.8%, iPSD: 6.3 ± 28.6%). The kinematic parameter SF increased by 2.7 ± 4.1% (p = 0.013, Fig 3) and ANKrom decreased by -4.1 ± 8.5% (p = 0.024, Fig 3). Other kinematic variables were not altered (ΔFOOT: 0.3 ± 5.3%, ΔANK: -0.2 ± 5.8%, ΔTIB: -0.8 ± 2.2%).

Bottom Line: Among biomechanical variables, step frequency increased by ~2.7% and the ankle range of motion decreased by ~4.1% post-MUM.Runners adopting a non rearfoot strike pre-MUM adopted a less plantarflexed foot strike pattern post-MUM while those adopting a rearfoot strike pre-MUM tended to adopt a less dorsiflexed foot strike pattern post-MUM.This strategy may aim at minimizing the overall load applied to the musculoskeletal system, including impact shock and muscle stretch.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Exercise Physiology (EA4338), University Savoie Mont Blanc, Le Bourget-du-Lac, France.

ABSTRACT
Ultramarathon runners are exposed to a high number of impact shocks and to severe neuromuscular fatigue. Runners may manage mechanical stress and muscle fatigue by changing their running kinematics. Our purposes were to study (i) the effects of a 110-km mountain ultramarathon (MUM) on tibial shock acceleration and lower limb kinematics, and (ii) whether kinematic changes are modulated according to the severity of neuromuscular fatigue. Twenty-three runners participated in the study. Pre- and post-MUM, neuromuscular tests were performed to assess knee extensor (KE) and plantar flexor (PF) central and peripheral fatigue, and a treadmill running bouts was completed during which step frequency, peak acceleration, median frequency and impact frequency content were measured from tibial acceleration, as well as foot-to-treadmill, tibia-to-treadmill, and ankle flexion angles at initial contact, and ankle range of motion using video analysis. Large neuromuscular fatigue, including peripheral changes and deficits in voluntary activation, was observed in KE and PF. MVC decrements of ~35% for KE and of ~28% for PF were noted. Among biomechanical variables, step frequency increased by ~2.7% and the ankle range of motion decreased by ~4.1% post-MUM. Runners adopting a non rearfoot strike pre-MUM adopted a less plantarflexed foot strike pattern post-MUM while those adopting a rearfoot strike pre-MUM tended to adopt a less dorsiflexed foot strike pattern post-MUM. Positive correlations were observed between percent changes in peripheral PF fatigue and the ankle range of motion. Peripheral PF fatigue was also significantly correlated to both percent changes in step frequency and the ankle angle at contact. This study suggests that in a fatigued state, ultratrail runners use compensatory/protective adjustments leading to a flatter foot landing and this is done in a fatigue dose-dependent manner. This strategy may aim at minimizing the overall load applied to the musculoskeletal system, including impact shock and muscle stretch.

Show MeSH
Related in: MedlinePlus