Neuromuscular characteristics and muscle power as determinants of running performance in endurance athletes : with special reference to explosive-strength training

Abstract

The aim of the study was to investigate the importance of neuromuscular characteristics and muscle power as determinants of running performance in endurance athletes. It was hypothesized that the running performance of endurance athletes would improve by training their neuromuscular characteristics, including improvements in muscle power and running economy. A total of 65 male athletes performed a 5-km (5K) or 10-km (10K) time trial and maximal 20-m (V₂₀ₘ) or 30-m (V₃₀ₘ) speed test on an indoor track, and running economy (RE) tests on a treadmill and on the track. Maximal anaerobic (MART) and aerobic treadmill running tests were used to determine maximal velocity in MART (VMART) and maximal oxygen uptake (VO₂ₘₐₓ). The 10K led to a significant reduction in the neuromuscular characteristics and track VO₂ₘₐₓ but these fatigue-induced changes did not differentiate between high (HC) and low (LC) caliber athletes. Instead, the mean contact times (CT) of constant velocity laps (CVL) during time trials correlated with V₁₀ₖ and V₅ₖ. V₅ₖ also correlated with V₂₀ₘ, CTs and stride rates in maximal 20-m run. HC had significantly shorter mean CTs of CVLs than LC. Preactivity of gastrocnemius (GA) in relation to the IEMG of the total contact phase during the CVLs was higher in HC than LC and the relative IEMGs of vastus lateralis in the propulsion phase compared to the IEMG of the maximal 20 m run were lower in HC than LC. The results suggest that ability to produce force rapidly throughout the 5K and 10K accompanied by optimal preactivation and contact phase activation were important for the running performance in endurance athletes. VMART correlated significantly with V₅ₖ, peak blood lactate concentration in MART (peak BlaMART), V₂₀ₘ and V₃₀ₘ, and CT in the maximal 20-m run but not with VO₂ₘₐₓ. Middle distance runners had a significantly higher VMART, V₃₀ₘ and peak BlaMART than triathletes and cross-country skiers further suggesting that VMART is determined by both neuromuscular and anaerobic characteristics and that VMART can be used as a measure of muscle power in endurance athletes. During the 9 weeks of training period the 5K time, RE and VMART improved in experimental group (E) but no changes were observed in control group (C). V₂₀ₘ and 5J increased in E and decreased in C. VO₂ₘₐₓ increased in C but no changes were observed in E. In the pooled data the changes in the 5K velocity during 9 weeks of training correlated with the changes in RE (VO₂) and VMART. These results showed that simultaneous explosive-strength and endurance training produced a significant improvement in the SK without changes in VO₂ₘₐₓ. This improvement was related to improved neuromuscular characteristics which were transferred into improved muscle power and running economy. In conclusion, a hypothetical model for distance running performance in endurance athletes was cpnstructed using the major determinants of performance of the present study: aerobic power, running economy, neuromuscular characteristics and muscle power.