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

本研究的目的是确定步频变化对活跃大学生心肺反应和感知运动强度（RPE）评分的影响。这个项目包括两个实验。实验1:10名受试者（5男5女）在电动跑步机上分别以3种次最大速度（120、150和180 re/min）进行5次6分钟改变步频的跑步。这五项试验包括以自由选择的步频（FCSF）和在每种速度下由+20%、+10%、-10%和-20%改变的FCSF进行跑步。在最后1分钟内测量摄氧量（VO_2）、心率（HR）、收缩压（SBP）、舒张压（DBP）和RPE。心率压积（PRP）作为心肌摄氧量的指标计算为HR （b/min） ×收缩压（mmHg） × 100。实验11：五名男性受试者在电动跑步机上以次最大速度（150或170米/分钟）进行三次30分钟的改变步频跑步。这三个试验包括FCSF和FCSF变化+10%和-10%的情况下运行。每5 min测量VO_2、HR、收缩压、舒张压、RPE、PRP。所有受试者的FCSF或FCFS改变了10%，此时心肺反应和RPE最小，尽管在6分钟的跑步过程中个体特征变化很大。然而，在改变步频的跑步过程中，PRP/VO_2与使用FCSF的跑步过程没有差异。在30 min时，除HR和RPE外，其他心肺反应均为稳态。虽然RPE随HR的增加而增加，但VO_2和血压没有增加。本项目结果表明，改变步频（+10%）的短时间和长时间跑步对有氧运动能力训练的心肺功能有许多好处。

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.