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  • Author: Desy Salvadego x
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Stefano Lazzer, Desy Salvadego, Paolo Taboga, Enrico Rejc, Nicola Giovanelli and Pietro E. di Prampero

Purpose:

To investigate the effects of an extreme uphill marathon on the mechanical parameters that are likely to affect the energy cost of running (Cr).

Methods:

Eleven runners (27–59 y) participated in the Etna SuperMarathon (43 km, 0–3063 m above sea level). Anthropometric characteristics, maximal explosive power of the lower limb (P max), and maximal oxygen uptake were determined before the competition. In addition, before and immediately after the race, Cr, contact (t c) and aerial (t a) times, step frequency (f), and running velocity were measured at constant self-selected speed. Then, peak vertical ground-reaction force (F max), vertical downward displacement of the center of mass (Δz), leg-length change (ΔL), and vertical (k vert) and leg (k leg) stiffness were calculated.

Results:

A direct relationship between Cr, measured before the race, and race time was shown (r = .61, P < .001). Cr increased significantly at the end of the race by 8.7%. Immediately after the race, the subjects showed significantly lower t a (–58.6%), f (–11.3%), F max (–17.6%), k vert (–45.6%), and k leg (–42.3%) and higher t c (+28.6%), Δz (+52.9%), and ΔL (+44.5%) than before the race. The increase of Cr was associated with a decrement in F max (r = –.45), k vert (r = –.44), and k leg (r = –.51). Finally, an inverse relationship between P max measured before the race and ΔCr during race was found (r = –.52).

Conclusions:

Lower Cr was related with better performance, and athletes characterized by the greater P max showed lower increases in Cr during the race. This suggests that specific power training of the lower limbs may lead to better performance in ultraendurance running competition.

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Nicola Giovanelli, Lea Biasutti, Desy Salvadego, Hailu K. Alemayehu, Bruno Grassi and Stefano Lazzer

Purpose: To evaluate the effects of a trail-running race on muscle oxidative function by measuring pulmonary gas exchange variables and muscle fractional O2 extraction. Methods: Eighteen athletes were evaluated before (PRE) and after (POST) a trail-running competition of 32 or 50 km with 2000 or 3500 m of elevation gain, respectively. During the week before the race, runners performed an incremental uphill running test and an incremental exercise by utilizing a 1-leg knee extension ergometer. The knee extension exercise was repeated after the end of the race. During the knee extension test, the authors measured oxygen uptake (V˙O2) and micromolar changes in deoxygenated hemoglobin (Hb)+myoglobin (Mb) concentrations (Δ[deoxy(Hb+Mb)]) on vastus lateralis with a portable near-infrared spectroscopy. Results: V˙O2peak was lower at POST versus PRE (−23.9% [9.0%]; P < .001). V˙O2peak at POST was lower than V˙O2 at the same workload at PRE (−8.4% [15.6%]; P < .050). Peak power output and time to exhaustion decreased at POST by −23.7% (14.3%) and −18.3% (11.3%), respectively (P < .005). At POST, the increase of Δ[deoxy(Hb+Mb)] as a function of work rate, from unloaded to peak, was less pronounced (from 20.2% [10.1%] to 64.5% [21.1%] of limb ischemia at PRE to 16.9% [12.7%] to 44.0% [18.9%] at POST). Peak Δ[deoxy(Hb+Mb)] values were lower at POST (by −31.2% [20.5%]; P < .001). Conclusions: Trail running leads to impairment in skeletal muscle oxidative metabolism, possibly related to muscle damage from repeated eccentric contractions. In association with other mechanisms, the impairment of skeletal muscle oxidative metabolism is likely responsible for the reduced exercise capacity and tolerance during and following these races.