Effects of an Uphill Marathon on Running Mechanics and Lower-Limb Muscle Fatigue

Purpose: To investigate the effects of an uphill marathon (43 km, 3063-m elevation gain) on running mechanics and neuromuscular fatigue in lower-limb muscles. Methods: Maximal mechanical power of lower limbs (MMP), temporal tensiomyographic (TMG) parameters, and muscle-belly displacement (D-m) were determined in the vastus lateralis muscle before and after the competition in 18 runners (age 42.8 +/- 9.9 y, body mass 70.1 +/- 7.3 kg, maximal oxygen uptake 55.5 +/- 7.5 mL . kg(-1) . min(-1)). Contact (t(c)) and aerial (t(a)) times, step frequency (f), and running velocity (v) were measured at 3, 14, and 30 km and after the finish line (POST). Peak vertical ground-reaction force (F-max), vertical displacement of the center of mass (Delta z), leg-length change (Delta L), and vertical (k(vert)) and leg (k(leg)) stiffness were calculated. Results: MMP was inversely related with race time (r = -.56, P = .016), t(c) (r = -.61, P = .008), and Delta z (r = -.57, P = .012) and directly related with F-max (r = .59, P = .010), t(a) (r = .48, P = .040), and k(vert) (r = .51, P = .027). In the fastest subgroup (n = 9) the following parameters were lower in POST (P < .05) than at km 3: t(a) (-14.1% +/- 17.8%), F-max (-6.2% +/- 6.4%), k(vert) (-17.5% +/- 17.2%), and k(leg) (-11.4% +/- 10.9%). The slowest subgroup (n = 9) showed changes (P < .05) at km 30 and POST in F-max (-5.5% +/- 4.9% and -5.3% +/- 4.1%), t(a) (-20.5% +/- 16.2% and -21.5% +/- 14.4%), t(c) (5.5% +/- 7.5% and 3.2% +/- 5.2%), k(vert) (-14.0% +/- 12.8% and -11.8% +/- 10.0%), and k(leg) (-8.9% +/- 11.5% and -11.9% +/- 12%). TMG temporal parameters decreased in all runners (-27.35% +/- 18.0%, P < .001), while D-m increased (24.0% +/- 35.0%, P = .005), showing lower-limb stiffness and higher muscle sensibility to the electrical stimulus. Conclusions: Greater MMP was related with smaller changes in running mechanics induced by fatigue. Thus, lower-limb power training could improve running performance in uphill marathons.