PHYSIOLOGICAL AND KINEMATIC CHARACTERISTICS OF YOUNGER AND OLDER TRAINED MALE RUNNERS.
R. Perkins, N. Swanson, A. Green, R. Pritchett, V. Nethery, L. D’Acquisto.
Nutrition, Exercise and Health Sciences. Central Washington University. Ellensburg, W.A.
Younger trained runners are typically able to outperform older trained runners in competitive races. PURPOSE: The purpose of this study was to compare kinematic (stride length (SL), stride rate (SR)) and select metabolic parameters between trained, competitive younger (N=11, 20+1 yr) and older (N=9, 45+5yr) male runners. METHODS: Height, weight, lean body mass and % adipose tissue (skinfold technique) were measured. Participants performed a series of submaximal treadmill running efforts (11.3, 12.9, 14.5, 16.1 km/hr) and a max run to exhaustion. SR (stds/min; manual count, stop watch), SL (m/std; velocity/SR), oxygen uptake (open-circuit spirometry, Parvo-Medic), heart rate (HR; telemetry), and blood lactate (YSI) responses were measured. RESULTS: Younger and older runners were similar in weight and height, with the older group having a lower lean body mass (p=0.07), and a greater % adipose tissue (p<0.05). The younger runners had a greater VO2 max (60.9+2.2 vs 58.3+2.6 ml.kg-1.min-1), HR max (193+6 vs 178+7 bpm), and achieved a faster maximal running speed (19.8+0.7 vs 19.0+0.9 km.hr-1) compared to older runners (P<0.05). At a fixed blood lactate of 4 mM, the younger runners achieved a faster running speed compared to the older runners (16.7+1.2 vs 15.5+1.6 km.hr-1) (P=0.09). Overall, HR was higher during the submaximal runs for the younger compared to the older runners (P<0.05), while an ordinal interaction was found between age category and running speed for oxygen uptake (P<0.05) with the older runners having higher VO2 values at 14.5 and 16.1 km.hr-1. SL and SR increased with running speed regardless of group (p<0.05). Overall, the older runners had a greater SR compared to the younger runners for all submaximal runs (p<0.05). CONCLUSION: The younger runners were characterized by a greater maximal aerobic power, better running economy at higher submaximal speeds, and tendency to sustain a faster running speed at a fixed blood lactate. These characteristics would help explain why younger runners typically outperform older runners in competition. In addition, in order to maintain a given running speed, older trained runners utilized a greater stride rate. The greater stride rate for a given speed suggests less time spent in the air (swing phase), which may reduce ground reactive force upon subsequent foot strike, an outcome that may be desirable for the older runners.