Stride frequency in relation to oxygen consumption in experienced and novice runners (original) (raw)
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Optimal stride frequencies in running at different speeds
PLOS ONE
During running at a constant speed, the optimal stride frequency (SF) can be derived from the u-shaped relationship between SF and heart rate (HR). Changing SF towards the optimum of this relationship is beneficial for energy expenditure and may positively change biomechanics of running. In the current study, the effects of speed on the optimal SF and the nature of the u-shaped relation were empirically tested using Generalized Estimating Equations. To this end, HR was recorded from twelve healthy (4 males, 8 females) inexperienced runners, who completed runs at three speeds. The three speeds were 90%, 100% and 110% of self-selected speed. A self-selected SF (SF self) was determined for each of the speeds prior to the speed series. The speed series started with a free-chosen SF condition, followed by five imposed SF conditions (SF self , 70, 80, 90, 100 stridesÁmin-1) assigned in random order. The conditions lasted 3 minutes with 2.5 minutes of walking in between. SF self increased significantly (p<0.05) with speed with averages of 77, 79, 80 stridesÁmin-1 at 2.4, 2.6, 2.9 mÁs-1 , respectively). As expected, the relation between SF and HR could be described by a parabolic curve for all speeds. Speed did not significantly affect the curvature, nor did it affect optimal SF. We conclude that over the speed range tested, inexperienced runners may not need to adapt their SF to running speed. However, since SF self were lower than the SF opt of 83 stridesÁmin-1 , the runners could reduce HR by increasing their SF self .
Individual optimal step frequency during outdoor running
European Journal of Sport Science
This is the first study investigating preferred (self-selected) step frequency (PSF) in relation to optimal step frequency (OSF) during running at different speeds outside the laboratory. OSF was defined as the SF at which heartrate (HR) showed a minimum during running at a constant speed. We aimed for a high ecological validity, which prohibits the direct measurement of oxygen consumption. HR was used as a proxy of energy cost, as has previously been validated. After a practice session, 21 experienced recreational runners (12 female) ran in an out-and-back manner on a straight flat tarmac lane in three main sessions: (1) 27 min at fixed comfortable speed with PSF, (2) at the same speed but with different imposed SFs (range 140-200 steps min −1) and at PSF and (3) similarly but at 15% higher speed. Runners were paced by a cyclist. Second order polynomials fitted the individual SF-HR relations well. At comfortable speed (3.04 ± 0.28 m s −1) mean r 2 was 0.81 (range: 0.40-0.99) and PSF and OSF respectively were 165 ± 8 and 171 ± 8 steps min −1 (p < .05). Both increased (p < .05) by 3 steps min −1 at the 15% higher speed. SFs were negatively (−0.66 < r < −0.49, p < .05) related to body height. From the individual SF-HR relations we deduced that changing PSF to OSF would decrease median HR only by 0.5 beats min −1 , but for two participants meaningful reductions (1-3 beats min −1) were predicted. Outdoors, experienced recreational runners ran at a PSF slightly below OSF, but for most of them, there was little to gain in terms of HR reductions by increasing their SF to OSF.
Heart rate cost of running in track estimates velocity associated with maximal oxygen uptake
Physiology & Behavior, 2019
Background: Running velocity associated with VO 2 max (vVO 2 max) is a parameter widely used for exercise prescription and is related to endurance performance. However, the vVO 2 max determination usually requires a maximal effort test and equipped laboratory for expired gas analysis, what make difficulty its assessment. Objective: We aimed to test the validity of a simple method of vVO 2 max prediction through the heart rate cost of running (HRC) in a submaximal 6-min running test, both in treadmill and in a 400-meter track. Methods: Male recreational runners (n = 16; 30.3 ± 8.0 years; VO 2 max of 46.2 ± 3.2 ml·kg −1 ·min −1) randomly underwent an incremental test in treadmill with gas analysis, and a 3000-m time trial in a track, to determine vVO 2 max. Before every maximal test, participants also performed a submaximal 6-min running (~85% HRmax), both in the treadmill and in a track, to assess HRC (bpm −1 m·min −1) by dividing the sub-maximal running velocity by its respective HR. The vVO 2 max (km·h −1) was predicted by dividing the HRmax (bpm)/HRC (bpm −1 m·min −1). Results: No differences were verified (p > .05) among vVO 2 max determined both in the treadmill (13.8 ± 0.9 km·h −1) and track (13.6 ± 0.9 km·h −1) to those predicted by the HRC method both in treadmill (13.5 ± 0.8 km·h −1) and track (13.6 ± 1.0 km·h −1). The vVO 2 max measured directly with expired gas analysis was highly correlated with vVO 2 max estimated through HRC in treadmill and track (p < .05). Additionally, the intraclass correlation coefficient (ICC) and Bland-Altman technique revealed good agreement and reliability classified with substantial agreement [ICC = 0.673 (95% CI 0.064-0.886; p = .019)] and almost perfect agreement [ICC = 0.870 (95% CI 0.628-0.955 p = .0001)] between methods to identify vVO 2 max, respectively. Conclusion: A submaximal 6-min exercise test protocol to assess HRC of running was considered valid to estimate vVO 2 max of recreational runners both in treadmill and outdoor track.
The Effect Of Stride Frequency Variations On Running Performance At The Velocity Of Vo2Max
Medicine & Science in Sports & Exercise
Running economy(RE) is considered to be a critical factor to improve running performance. Stride frequency(SF) is an important variable for determining RE. The importance of SF has gained more attention in recent years, especially for recreational runners. However, no previous research has investigated the interaction between running performance and SF at the velocity of VO2max. PURPOSE: To investigate the effect of five different SF variations on running performance until volitional fatigue at the velocity of VO2max. METHODS: Fourteen male recreational runners (Age = 25.8 ± 4.96 years, Height = 171 ± 6.2cm, Body Mass = 71.9 ± 7.5kg) measured VO2max (54 ± 5.6 ml/kg/min) and preferred stride frequency (PSF; 89.3 ± 4 / min) through a graded exercise test (GXT) and running session, respectively. Running speed was determined based on each individual's VO2max via the metabolic equation for gross VO2 in metric units by ACSM. Participants ran on the treadmill (0% grade) with five SF conditions (PSF, ±5%, ±10%) until time to exhaustion. Data were analyzed using a one way ANOVA with repeated measures and Tukey HSD post hoc. RESULTS: The total running performance (time, distance), energy expenditures (kcal), and oxygen consumption (VO2) were statistically significant among SF variations (p<0.05). Additionally, the respiratory exchange ratio iii (RER), respiratory rate (RR), and ventilation (VE) were no statistically significant (p>0.05). CONCLUSION: The SF variations have a significant influence on running performance. The relationship between SF variations and other variables (RER, RR, VE) were possibly related to the central governor theory to delay the onset of fatigue. These results suggest that recreational runners could use a 105% of PSF to improve running performance with the better RE.
The Relationship between Running Power and Running Economy in Well-Trained Distance Runners
Sports, 2018
A novel running wearable called the Stryd Summit footpod fastens to a runner’s shoe and estimates running power. The footpod separates power output into two components, Stryd power and form power. The purpose of this study was to measure the correlations between running economy and power and form power at lactate threshold pace. Seventeen well-trained distance runners, 9 male and 8 female, completed a running protocol. Participants ran two four-minute trials: one with a self-selected cadence, and one with a target cadence lowered by 10%. The mean running economy expressed in terms of oxygen cost at self-selected cadence was 201.6 ± 12.8 mL·kg−1·km−1, and at lowered cadence was 204.5 ± 11.5 mL·kg−1·km−1. Ventilation rate and rating of perceived exertion (RPE) were not significantly different between cadence conditions with one-tailed paired t-test analysis (ventilation, p = 0.77, RPE, p = 0.07). Respiratory exchange ratio and caloric unit cost were significantly greater with lower ca...
Energetically optimal stride frequency in running: the effects of incline and decline
The Journal of experimental biology, 2011
At a given running speed, humans strongly prefer to use a stride frequency near their 'optimal' stride frequency that minimizes metabolic cost. Although there is no definitive explanation for why an optimal stride frequency exists, elastic energy usage has been implicated. Because the possibility for elastic energy storage and return may be impaired on slopes, we investigated whether and how the optimal stride frequency changes during uphill and downhill running. Presuming a smaller role of elastic energy, we hypothesized that altering stride frequency would change metabolic cost less during uphill and downhill running than during level running. To test this hypothesis, we collected force and metabolic data as nine male subjects ran at 2.8 m s(-1) on the level, 3 deg uphill and 3 deg downhill. Stride frequency was systematically varied above and below preferred stride frequency (PSF ±8% and ±15%). Ground reaction force data were used to calculate potential, kinetic and total...
Self-optimization of Stride Length Among Experienced and Inexperienced Runners
International journal of exercise science, 2017
Experienced runners appear to naturally select a stride length which is optimal for minimizing oxygen uptake. However, whether this ability is naturally built into the human body or whether it is learned through experience has not been previously tested. This study investigated whether inexperienced runners are as capable as experienced runners of self-optimizing stride length to minimize oxygen uptake. Thirty-three subjects (nineteen experienced and fourteen inexperienced) ran for twenty-minutes while preferred and economical stride lengths were measured. A t-test checked for differences between the experienced and inexperienced groups in the percent increase of oxygen uptake due to not running at the most economical stride length. No difference was found between groups with the increase in oxygen uptake due to not being optimized (p=0.47). The average percent increase in oxygen uptake above the most economical for inexperienced and experienced runners was 1.8% and 1.2% respectivel...
Energy Cost and Stride Pattern Variability of Elite Runners on the Treadmill
2008
Preliminary observations on individual freely chosen stride patterns during running at various velocities demonstrated discrepancies from those reported in the literature. This phenomenon was further investiga ted in relation to energy cost in 9 elite runners (X ± s, age: 27 ± 4.5 yr, height: 174.9 ± 2.5 cm, weight: 65.9 ± 6.3 kg and V02max : 67.4 ± 3.7 ml kg-I min~I). All runners had previous treadmill experience and performed a maximal multistage test. Initial treadmill speed of 9 km/h was increased by 1 km/h every 2 min. Measurements of stride frequency (accelerometer) and V02 (Douglas bag method) started at 11 km/h. As with V02 , the average values of stride length and stride frequency increase linearly with running speed, yielding high correlations in all cases (r > 0.99). The freely chosen stride pattern of individual runners however, was not always consistent with the average pattern. Discrepan cies were more pronounced at low speeds, although they also occurred at high ...
Applied Physiology, Nutrition, and Metabolism, 2013
This study assessed the between-test reliability of oxygen cost (O C ) and energy cost (E C ) in distance runners, and contrasted it with the smallest worthwhile change (SWC) of these measures. O C and E C displayed similar levels of within-subject variation (typical error < 3.85%). However, the typical error (2.75% vs 2.74%) was greater than the SWC (1.38% vs 1.71%) for both O C and E C , respectively, indicating insufficient sensitivity to confidently detect small, but meaningful, changes in O C and E C .
Effect of free versus constant pace on performance and oxygen kinetics in running
Medicine and Science in Sports and Exercise, 2001
BILLAT, V. L., J. SLAWINSKI, M. DANEL, and J. P. KORALSZTEIN. Effect of free versus constant pace on performance and oxygen kinetics in running. . Purpose: This study tested the hypothesis that free versus constant pace enhanced the performance (i.e., distance run) in suprathreshold runs between 90 and 105% of the velocity associated with the maximal oxygen consumption determined in an incremental test (vV O 2max ). Moreover, we hypothesized that variable pace could decrease the slow phase of oxygen kinetics by small spontaneous recoveries during the same distance run at an average velocity. Method: Eleven long-distance runners performed nine track runs performed until exhaustion. Following an incremental test to determine vV O 2max , the runners performed, in a random order, four constant-velocity runs at 90, 95, 100, and 105% of vV O 2max to determine the time to exhaustion (tlim90, tlim95, tlim100, and tlim105) and the distance limit at 90, 95, 100 and 105% of vV O 2max (dlim90, dlim95, dlim100, and dlim105). Finally, they performed the distance limit determined in the constant velocity runs but at variable velocity according to their spontaneous choice. Results: The coefficient of variation of velocity (in percent of the average velocity) was small and not significantly different between the four free pace dlim (4.2 Ϯ 1.3%, 4.8 Ϯ 2.4%, 3.6 Ϯ 1.1%, and 4.6 Ϯ 1.9% for dlim90, dlim95, dlim100, and dlim105, respectively; P ϭ 0.40). Performances were not improved by a variable pace excepted for the dlim at 105% vV O 2max (4.96 Ϯ 0.6 m·s Ϫ1 vs 4.86 Ϯ 0.5 m·s Ϫ1 , P ϭ 0.04). Oxygen kinetics and the volume of oxygen consumed were not modified by this (low) variation in velocity. Conclusion: These results indicate that for long-distance runners, variable pace modifies neither performance nor the oxygen kinetics in all-out suprathreshold runs.