Sex Differences in Neuromuscular Fatigue and Changes in Cost of Running after Mountain Trail Races of Various Distances

Abstract

Introduction: Females have been shown to experience less neuromuscular fatigue than males in knee extensors (KE) and less peripheral fatigue in plantar flexors (PF) following ultra-trail running, but it is unknown if these differences exist for shorter trail running races and whether this may impact running economy. The purpose of this study was to characterize sex differences in fatigability over a range of running distances and to examine possible differences in the postrace alteration of the cost of running (Cr).Methods: Eighteen pairs of males and females were matched by performance after completing different races ranging from 40 to 171 km, divided into SHORT vs LONG races (< 60 and > 100 km, respectively). NM function and Cr were tested before and after each race. NM function was evaluated on both KE and PF with voluntary and evoked contractions using electrical nerve (KE and PF) and transcranial magnetic (KE) stimulation. Oxygen uptake, respiratory exchange ratio and ventilation were measured on a treadmill and used to calculate Cr.Results: Compared to males, females displayed a smaller decrease in maximal strength in KE (−36% vs −27%, respectively, p < 0.01), independent of race distance. In SHORT only, females displayed less peripheral fatigue in PF compared to males (Δ peak twitch: −10% vs −24%, respectively, p < 0.05). Cr increased similarly in males and females.Conclusion: Females experience less neuromuscular fatigue than men following both 'classic' and 'extreme' prolonged running exercises but this does not impact the degradation of the energy cost of running.

Disparate Mechanisms of Fatigability in Response to Prolonged Running versus Cycling of Matched Intensity and Duration

“…Two of the most common modalities of endurance exercise are running and cycling. Although an abundance of research has characterized the neuromuscular consequences of these respective exercise modes (3,4,10,11), no study has directly compared them. However, some insight can be gained by comparing the results of Lepers et al (12) and Place et al (13), who assessed the neuromuscular responses in the quadriceps after 5 h of cycling and running, respectively, at 55% of the power output/speed associated with maximum oxygen consumption ( VO 2max ).…”

Sex‐related differences and effects of short and long trail running races on resting muscle‐tendon mechanical properties

“…The testing procedures for MVC torque measurements and visual analog scale (VAS) score were similar to previous studies 21,24–26 …”

Is There Evidence for the Development of Sex-Specific Guidelines for Ultramarathon Coaches and Athletes? A Systematic Review

“…Two studies investigated sex differences in neuromuscular fatigue (Table 3 ), with both finding that female runners demonstrate less peripheral fatigue in the plantar flexors [ 36 , 37 ]. No sex differences were seen in peripheral fatigue of the knee extensors or central fatigue, although males did have higher ratings for general fatigue in races < 60 km long [ 36 , 37 ].…”

“…No difference in plantar flexor MVC (-26% vs -31%). No significant sex differences in measures of central fatigue Besson et al[ 37 ] 36 athletes (18 females and 18 males) who competed in either short (< 60 km) or long (> 100 km) ultramarathons Knee extensor and plantar flexor MVC, evoked responses, oxygen uptake, respiratory exchange ratio (energy cost of running) Cohort study Low Males had greater decrease in knee extensor MVC for all race distances (− 36% vs − 27%, p < 0.01). No significant difference in plantar flexor MVC Females displayed less peripheral fatigue in plantar flexors than males in races < 60 km (Δ peak twitch: − 10% vs − 24%, p < 0.05) Males had higher ratings for general fatigue in races < 60 km ( p = 0.027).…”