Effects Of Stride Frequency Research Articles

The Effect of Stride Frequency on Running Economy and Running Distance During High Intensity Treadmill Running

Running economy (RE; ml·kg-1·km1) considers as a valid predictor of endurance running performance. Theoretically, improving RE allows runners to cover more distance at constant speed or run faster at a given distance. Stride frequency (SF) is one of the important parameters that affects running performance. The purpose of this study was to investigate the effect of SF on RE and distance while running on the treadmill at the speed of V̇O2max (sV̇O2max) until volitional fatigue. The second purpose was to determine a relationship between RE and running distance during high intensity running. We hypothesized that both RE and running distance would affect significantly by SF variations and there is a positive relationship between RE and running distance. Ten male recreational runners (age: 25.8 ± 5.0 yrs, height: 171.4 ± 6.2 cm, mass: 71.9 ± 7.5 kg) completed total seven experimental sessions including graded exercise test and running session for determining V̇O2max (55.4 ± 5.9 ml·kg-1·min1) and preferred SF (PSF; 88.0±3.9 strides/min), respectively. Running speed was calculated based on V̇O2max using the metabolic equation; V̇O2 (ml·kg-1·min1) = [0.2 × Speed(m/min)] + 3.5(ml·kg-1·min1). Participants performed five separate running sessions (PSF, ±5%, ±10%) on the treadmill at the sV̇O2max with 0% gradient until volitional fatigue. A computer-based metronome was played in order to help maintain a target SF while running. The running distance was significantly different among SF variations (p < 0.01) and all participants ran the greater distance at 105% PSF. However, RE was not statistically significant (p = 0.19) across the SF conditions. There was a low correlation between RE and running distance (r = 0.214, p = 0.14). SF variations have a significant influence on running distance, but not RE during high intensity running. Recretional runners may use 105% PSF during high intensity running to train both aerobic and anaerobic capacity.

Kinematics of gecko climbing: the lateral undulation pattern

Geckos are exceptional at terrestrial locomotion and can move on diverse terrains and surface orientations. Geckos employ cyclical lateral bending of their flexible trunk and tail to coordinate their limb movements. In this study, using an optical motion capture system, we measured the kinematics of this lateral undulation pattern of geckos (Gekko gecko) at increasing locomotion velocity on horizontal plane, 45° inclined plane and vertical plane, respectively. We observed that geckos increased their stride frequency and stride length to increase the locomotion velocity; the effect of stride frequency on the locomotion velocity was greater than that of stride length. With increasing speed, the lateral undulation pattern changed from standing to travelling. The waveform of the trunk movement appeared as single-peak curves in a standing wave at low speeds and was propagated from head to tail in a travelling wave at high speeds. Analysis of the anatomical characteristics and axial angular kinematics of the two patterns revealed that the lateral undulation pattern results from girdle rotation and axial muscle activity. Thus, the travelling wave is the combined effect of the lateral trunk bending and deflection of the body relative to the motion direction.

The Effect Of Stride Frequency On Running Economy In Collegiate And Recreational Runners

The Effect Of Stride Frequency On Running Economy In Collegiate And Recreational Runners

Effect of stride frequency on thermoregulatory responses during endurance running in distance runners

Changing stride frequency may influence oxygen uptake and heart rate during running as a function of running economy and central command. This study investigated the influence of stride frequency manipulation on thermoregulatory responses during endurance running. Seven healthy endurance runners ran on a treadmill at a velocity of 15km/h for 60min in a controlled environmental chamber (ambient temperature 27°C and relative humidity 50%), and stride frequency was manipulated. Stride frequency was intermittently manipulated by increasing and decreasing frequency by 10% from the pre-determined preferred frequency. These periods of increase or decrease were separated by free frequency running in the order of free stride frequency, stride frequency manipulation (increase or decrease), free stride frequency, and stride frequency manipulation (increase or decrease) for 15min each. The increased and decreased stride frequencies were 110% and 91% of the free running frequency, respectively (196±6, 162±5, and 178±5steps/min, respectively, P<0.01). Compared to the control, stride frequency manipulation did not affect rectal temperature, heart rate, or the rate of perceived exhaustion during running. Whole-body sweat loss increased significantly when stride frequency was manipulated (1.48±0.11 and 1.57±0.11kg for control and manipulated stride frequencies, respectively, P<0.05), but stride frequency had a small effect on sweat loss overall (Cohen's d=0.31). A higher mean skin temperature was also observed under mixed frequency conditions compared to that in the control (P<0.05). While the precise mechanisms underlying these changes remain unknown (e.g. running economy or central command), our results suggest that manipulation of stride frequency does not have a large effect on sweat loss or other physiological variables, but does increase mean skin temperature during endurance running.

Effects of stride frequency and foot position at landing on braking force, hip torque, impact peak force and the metabolic cost of running in humans.

Endurance runners are often advised to use 90stridesmin(-1), but how optimal is this stride frequency and why? Endurance runners are also often advised to maintain short strides and avoid landing with the feet too far in front of their hips or knees (colloquially termed 'overstriding'), but how do different kinematic strategies for varying stride length at the same stride frequency affect economy and impact peaks? Linear mixed models were used to analyze repeated measures of stride frequency, the anteroposterior position of the foot at landing, V̇O2 , lower extremity kinematics and vertical ground reaction forces in 14 runners who varied substantially in height and body mass and who were asked to run at 75, 80, 85, 90 and 95stridesmin(-1) at 3.0 m s(-1). For every increase of 5stridesmin(-1), maximum hip flexor moments in the sagittal plane increased by 5.8% (P<0.0001), and the position of the foot at landing relative to the hip decreased by 5.9% (P=0.003). Higher magnitudes of posteriorly directed braking forces were associated with increases in foot landing position relative to the hip (P=0.0005) but not the knee (P=0.54); increases in foot landing position relative to the knee were associated with higher magnitudes (P<0.0001) and rates of loading (P=0.07) of the vertical ground reaction force impact peak. Finally, the mean metabolically optimal stride frequency was 84.8±3.6stridesmin(-1), with 50.4% of the variance explained by the trade-off between minimizing braking forces versus maximum hip flexor moments during swing. The results suggest that runners may benefit from a stride frequency of approximately 85stridesmin(-1) and by landing at the end of swing phase with a relatively vertical tibia.

Effect of stride frequency on the energy cost of walking in obese teenagers

The aim of this study was to compare the energy cost of obese and non-obese teenagers while walking at their preferred speed and different stride frequencies. Twelve obese and twelve non-obese teenagers walked continuously on the treadmill at their most comfortable speed for 6 periods of 4 min each. Each period corresponded to a specific stride frequency: preferred (PSF), force-driven harmonic oscillator (FDHO), PSF + 10%, PSF + 20%, PSF − 10% and PSF − 20%. Cardiorespiratory parameters were collected between the 3rd and 4th minute of each stage, and used to calculate the energy cost of walking (EC). The main results showed a significantly higher cost of walking expressed relative to lean body mass. In addition, a U-shaped relationship between EC and stride frequency was shown in both groups, with PSF and FDHO leading to a significantly lower value compared to all other frequencies. This showed first, that FDHO is a good predictor of PSF and minimal energy cost of walking in both groups, and second, that excess body fat does not affect the relationship between energy expenditure and stride frequency. Walking at lower or higher than preferred frequencies could be used as an exercise mode to promote weight loss in obese teenagers.

Relative contribution of walking velocity and stepping frequency to the neural control of locomotion

Stepping frequency is tightly coupled to walking velocity during natural locomotion. In a recent model, we demonstrated that walking velocity determines stride frequency, governs the active feedback control of the swing and determines the swing phase dynamics that governs foot movement. Here, we questioned whether the swing phase dynamics reflect independent effects of stride frequency and walking velocity. Foot movements were measured with a motion detection system (Optotrak) while subjects walked at 0.6-2.1 m/s on a treadmill. Stepping frequencies of 1.3-2.8 Hz were generated with pacing cues at each walking velocity. In the 'iso-velocity' condition, peak forward toe velocity during the swing phases was related to walking velocity and did not vary with alterations in stride frequency. In the 'iso-frequency' condition, in contrast, stepping frequency altered the relationship between toe acceleration and toe position in the fore-aft direction. The cycle frequency, main sequence (peak velocity vs. amplitude) relationships, and the shape of the phase-plane trajectories of the swing phases also reflected this relationship. The data were modeled by decoupling stepping frequency from walking velocity, while maintaining active feedback control dependent on frequency. The latter predicted both the dominant shape of the phase plane trajectories and the main sequence relationships. Thus, according to the model, walking velocity and stride frequency are independent central variables that control the dynamics of the swing phases and stepping. The ability to decouple stride frequency from walking velocity may help in navigating over uneven terrain or when executing curved trajectories while maintaining a constant velocity.

Variability of reciprocal aiming movements during standing: The effect of amplitude and frequency

This study investigated the variability of the center of pressure (COP) trajectory during voluntary whole-body oscillations. While standing upright on a force platform, eight subjects leaned forward and backward so as to perform reciprocal aiming movements with their COP at a prescribed frequency (F) and amplitude (A) using online visual feedback of their COP location. A total of 25 F-A combinations were tested for each subject (3 < A < 9 cm, and 0.35 < F < 1.35 Hz). Spatial and temporal variability of the COP was assessed by computing the standard deviation (SD) and coefficient of variation (CV) of the amplitude (trough to peak) and frequency (peak to peak) of the COP cycles within each trial, respectively. The results revealed that all variability indices depended on the prescribed F and A. Concerning the effect of spatial constraints on spatial variability, SD spatial increased as a function of A, while CV spatial decreased as function of A. A similar pattern was observed with respect to the effect of temporal constraints on temporal variability (SD temporal increased as a function of F, while CV temporal decreased). As for "cross-over" effects, there was an effect of F on spatial variability, such that SD spatial and CV spatial were minimal at 0.6 Hz. For the "cross over" effect of A on temporal variability, both SD spatial and CV spatial decreased as a function of A. Across the experimental conditions, there were weak or no correlations between variability in the time and space domain. Comparisons with an earlier study on human gait (Danion F, Varraine E, Bonnard M, Pailhous J. Stride variability in human gait: the effect of stride frequency and stride length. Gait Posture 2003;18:69-77) suggest that the effects of spatial constraints are relatively task independent, whereas the effects of temporal constraints depend on the nature of the motor task that is performed.

Effects of stride frequency on mechanical power and energy expenditure of walking

The energetics and mechanics of walking were investigated at different speeds, both at the freely chosen stride frequency (FCSF) and at imposed ones (up to +/- 40% of FCSF). Metabolic energy expenditure was minimized at FCSF for each speed. Motion analysis allowed to calculate: the mechanical internal work rate (Wint), needed to move the segments with respect to the body center of mass (bcm); the external work rate (Wext), necessary to move bcm in the environment; and the total work rate (Wtot), equal to Wint+Wext. Wtot explains the metabolic optimization only at high speeds, while Wext, differently from previously reported, displays minima which better predict FCSF at all speeds (exception made for 1.39 m.s-1). This is probably caused by an overestimation of Wint due to a more ballistic movement of the limbs at low speeds (and low frequencies). The tendency of Wext to increase at high frequencies is due to a persistent minimal vertical excursion of bcm (about 0.02 m, the "locomotory dead space"). While the match between mechanics and energetics (at FCSF and imposed frequencies) occurs to a certain extent, it could be improved by removing the methodological assumptions about the energy transfer between segments and by the possibility to account for the coactivation of antagonist muscles.