Effects of altered stride frequency on cardiorespiratory responses and ratings of perceived exertion during submaximal running

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The purpose of this project was to determine the effects of stride frequency variations on cardiorespiratory responses and ratings of perceived exertion (RPE) in active university students. The project consists of two experiments. Experiment 1 : Ten subjects (5 males and 5 females) performed five 6 min altered stride frequency runs on a motorized treadmill at three submaximal speeds (120, 150 and 180 re/min), respectively. The five trials involved running with a freely chosen stride frequency (FCSF) and a FCSF altered by +20%, +10%, -10% and -20% at each speed. During these runs, oxygen uptake (VO_2), heart rate (HR), systolic (SBP) and diastolic (DBP) blood pressure and RPE were measured during the last 1 min. As an index of myocardial oxygen uptake, rate pressure product (PRP) was calculated as equal to HR (b/min)x SBP (mmHg)x 100. Experiment 11 : Five male subjects performed three 30 min altered stride frequency runs on a motorized treadmill at a submaximal speed (150 or 170 m/min). The three trials involved running with a FCSF and a FCSF altered by +10% and -10%. During these runs, VO_2, HR, SBP and DBP blood pressure, RPE and PRP were measured every 5 min. All subjects exhibited a FCSF or a FCFS altered by +10% at which cardiorespiratory responses and RPE were minimized, although the individual profiles varied considerably during 6 min runs. However, PRP/VO_2 during altered stride frequency runs did not differ from during runs with a FCSF. During 30 min runs, cardiorespiratory responses exhibited in steady-state except HR and RPE. Although RPE increased with increases in HR, VO_2 and blood pressure did not increase. The results of this project suggest that both short and prolonged duration running with altered stride frequency (+10%) offer many advantages to cardiorespiratory functions for training of aerobic work capacity.