Effects of a 5-h hilly running on ankle plantar and dorsal flexor force and fatigability

Abstract

This study aimed to examine the effects of a 5-h hilly run on ankle plantar (PF) and dorsal flexor (DF) force and fatigability. It was hypothesised that DF fatigue/fatigability would be greater than PF fatigue/fatigability. Eight male trail long distance runners (42.5 ± 5.9 years) were tested for ankle PF and DF maximal voluntary isokinetic contraction strength and fatigue resistance tests (percent decrement score), maximal voluntary and electrically evoked isometric contraction strength before and after the run. Maximal EMG root mean square (RMS(max)) and mean power frequency (MPF) values of the tibialis anterior (TA), gastrocnemius lateralis (GL) and soleus (SOL) EMG activity were calculated. The peak torque of the potentiated high- and low-frequency doublets and the ratio of paired stimulation peak torques at 10 Hz over 100 Hz (Db10:100) were analysed for PF. Maximal voluntary isometric contraction strength of PF decreased from pre- to post-run (-17.0 ± 6.2%; P < 0.05), but no significant decrease was evident for DF (-7.9 ± 6.2%). Maximal voluntary isokinetic contraction strength and fatigue resistance remained unchanged for both PF and DF. RMS(max) SOL during maximal voluntary isometric contraction and RMS(max) TA during maximal voluntary isokinetic contraction were decreased (P < 0.05) after the run. For MPF, a significant decrease for TA (P < 0.05) was found and the ratio Db10:100 decreased for PF (-6.5 ± 6.0%; P < 0.05). In conclusion, significant isometric strength loss was only detected for PF after a 5-h hilly run and was partly due to low-frequency fatigue. This study contradicted the hypothesis that neuromuscular alterations due to prolonged hilly running are predominant for DF.

Alterations in Postural Control during the World's Most Challenging Mountain Ultra-Marathon

“…In our study, it appears that the specificities of this mountain race (large uphill/downhill sections; unstable ground) led to greater muscle fatigue of the ankle plantar than the dorsi-flexor muscles and the hip adductors and abductors. These data are consistent with the observations made by Fourchet et al, who reported greater ankle plantar than dorsi-flexor strength loss after a 5-h hilly run [55].…”

“…During MUM, great fatigue of the plantar flexors has been reported, whereas in dorsi-flexors [31], [47], [55], the magnitude of fatigue appears less [55]. This increased fatigue-induced strength imbalance likely influences the control of AP movements.…”

High-Intensity Running and Plantar-Flexor Fatigability and Plantar-Pressure Distribution in Adolescent Runners

“…Interestingly, these results were not different when calculated over the first 30 contractions only (plantar flexors: 29.7%, P ¼ .04, power ¼ 0.49, ES ¼ 1.09; dorsiflexors: 17.3%, P ¼ .16, power ¼ 0.17, ES ¼ 0.64), as recommended, 10 versus the values we calculated over 50 contractions. These changes affecting only the plantar flexors are in line with previous studies in which the plantar flexors of adults were subjected to fatigue after prolonged 29,30 or shorter-term (ie, 13minute) running. 1 As suggested, 5 one may assume that, to manage fatigued conditions at such a high running speed, the participants unconsciously engaged a midfoot landing strategy, which consequently altered the loading demands on the plantar flexors.…”

Effects of the foot strike pattern on muscle activity and neuromuscular fatigue in downhill trail running

“…Since the work performed at the ankle is substantial in uphill running (Roberts & Belliveau, ), increasing PF fatigue/damage in downhill sections will likely affect performance in the subsequent uphill sections. Furthermore, trail running may mainly cause greater alterations of muscle function in PF than in dorsiflexors, as previously observed after a 5‐h hilly run (Fourchet et al., ).…”

“…Since the work performed at the ankle is substantial in uphill running (Roberts & Belliveau, 2005), increasing PF fatigue/damage in downhill sections will likely affect performance in the subsequent uphill sections. Furthermore, trail running may mainly cause greater alterations of muscle function in PF than in dorsiflexors, as previously observed after a 5-h hilly run (Fourchet et al, 2011). The lower VL activity observed with anterior patterns may result from less pronounced knee extension at initial contact which may decrease VL pre-activation (Shih et al, 2013) and/or from a lower negative work developed by KE muscles during the braking phase (Hamill et al, 2014).…”