Relationship Among Physiological, Perceptual, And Biomechanical Variables During Exercise On A Non-motorized Treadmill In D2 Cross-country Athletes

Abstract

PURPOSE: The purpose of this study was to examine the relationship between physiological, perceptual, and biomechanical variables during exercise on a non-motorized treadmill (NMT) in cross-country athletes. METHODS: Thirteen female cross-country Division II athletes (age, 20.77 ± 3.27 yrs; height, 161.92 ± 5.48 cm; weight, 55.54 ± 6.45 kg) participated in separate familiarization and testing sessions. On day one (familiarization), participants performed a treadmill protocol that consisted of a 5-min warm-up walk, 5-min walk, 5-min run, and 5-min cool-down on the NMT. Participants’ velocity was recorded every minute to determine average self-selected pace for walking and running. Day two (testing day) consisted of performing the treadmill protocol with the previously determined velocities. Heart rate (HR), rating of perceived exertion (RPE), oxygen uptake (VO2), vertical GRF (GRFv), horizontal GRF (GRFh), power, and velocity was recorded and steady-state minutes were averaged and used for analysis. Separate Pearson’s r correlation analyses were used to determine the relationship among HR, RPE, VO2, GRFv, GRFh, power, and velocity. RESULTS: There was a significant strong positive correlation in walking between in HR and velocity (r = 0.75; p = 0.003), horizontal force (r = 0.73; p = 0.004), and power (r = 0.76; p = 0.002). There was a significant positive strong correlation in running between HR and velocity (r= 0.76; p= 0.002), power (r= 0.76; p= 0.002). There was a significant positive strong correlation in running between VO2 and running velocity (r= 0.71; p= 0.006), GRFh (r= 0.69; p= 0.008), and power (r= 0.72; p= 0.005). There was no significant (p > 0.05) correlation for all other variables in walking and running conditions. CONCLUSIONS: The results indicate that VO2 has strong correlations with running velocity, force, and power, and that HR has strong correlations with running velocity and power. VO2 and HR are indicators of exertion in running conditions. Since the runners were in a steady-state condition, these results suggest that an increase in exertion—indicated by cardiovascular and metabolic responses—also requires an increase in kinetic measures. Because the NMT requires users to self-propel, the results suggest mechanics of running on a curved-NMT may influence physiological responses.