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At least 541 records · Page 30Linked to original sources

PubMed2003

Biomechanical analysis of running in military boots with new and degraded insoles.

PURPOSE: The purpose of the present study was to investigate the influence of degradation using repeated impacts on the ability of different shock-absorbing insoles to reduce peak impact loading during running in military boots. METHODS: Four insole types were degraded mechanically to simulate typical running loads that occur during approximately 100 km of running. The influence of insole mechanical degradation on stiffness and impact-absorbing ability was assessed using standard test procedures. The ability of new and degraded insole samples to reduce peak impact loading during running was assessed by monitoring peak impact force and rate of loading. In addition, the influence of insoles on sagittal plane kinematics was quantified by measurement of hip, knee, and ankle joint flexion. RESULTS: Insole mechanical degradation resulted in an increase in mechanical stiffness and a decrease in ability to reduce mechanical impacts for all test insoles. Measurements taken during running indicated that only one insole type reduced peak impact loading when new, as indicated by a significant (P< 0.05) reduction in peak rate of loading. The ability of this insole type to reduce peak rate of loading during running was maintained after mechanical degradation. This insole was also found to significantly (P< 0.05) reduce peak ankle dorsiflexion. CONCLUSION: The present study identifies an insole type that reduces peak rate of loading during running both when new and when mechanically degraded. It is suggested that this indicates an insole that could potentially reduce the frequency of overuse injuries. Based on these results, this insole is recommended for use in the investigation of the practical use of insoles by military recruits, particularly for study of the influence on injury occurrence.

Adult↗

PubMed2003

Reexamination of validity and reliability of the CSA monitor in walking and running.

PURPOSE: To evaluate the reliability and validity of the CSA (model 7164) accelerometer (MTI) in a wide walking-running speed range in laboratory and field. METHOD: Twelve male subjects performed three treadmill walking/running sessions and one field trial with the same continuous protocol involving progressively increasing velocities at 5 min per interval from 3 to 6 km x h(-1) (walking) and 8 to 20 km x h(-1) (running). In the field trial, this protocol was terminated after 35 min (14 km.h(-1)), but the trial then extended with 5-km running at a freely chosen velocity. In both scenarios, two CSAs were mounted on each hip and the step frequency measured at each velocity. Oxygen uptake VO(2) x kg(-1) was measured on the last two treadmill sessions. Correlation analyses were performed for mean CSA output relationship with speed, VO(2) per kilogram, and step frequency. RESULTS: In all trials, CSA output rose linearly (R2 = 0.92, P < 0.001) with increasing speed until 9 km.h-1 but remained at approximately 10000 counts.min-1 during running, thus underestimating VO(2) per kilogram at speeds > 9 km x h(-1). Estimation errors increased with speed from 11% (P < 0.01) at 10 km x h(-1) to 48% (P < 0.001) at 16 km x h(-1), when assuming a linear relationship. Freely chosen velocities in the field trial ranged from 10.9 to 16.3 km.h-1. No difference in the CSA-speed relationship was observed between the two scenarios. Differences in CSA output between subjects could partially be attributed to differences in step frequency (R = -0.34 (P = 0.02) for walking and R = -0.63 (P < 0.001) for running). CONCLUSION: CSA output increases linearly with speed in the walking range but not in running, presumably due to relatively constant vertical acceleration in running. Between-subject reliability was related to step frequency because CSA data are filtered most at higher movement frequencies. Epidemiological CSA data should thus be interpreted with these limitations in mind.

Acceleration↗

PubMed2005

Preferred transition speed between walking and running: effects of training status.

PURPOSE: This study was conducted to identify the preferred transition speed (PTS) between walking and running and the energetically optimal transition speed (ETOS), in runners and nonrunners. METHODS: A total of 19 young men were asked to walk on a treadmill at 5 km.h(-1). Speed was then increased by 0.2 km.h(-1) every minute. Subjects were instructed to start running at a particular speed they felt was easier. PTS for each subject was determined as the mean of the walk-run and the run-walk transitions. Subjects were also asked to walk and to run for 5 min at each of the following velocities: PTS - 1 km.h(-1), PTS - 0.5 km.h(-1), PTS, PTS + 0.5 km.h(-1), and PTS + 1 km.h(-1). This procedure was performed twice, once walking and once running, at all speeds. Physiologic measurements of oxygen consumption, heart rate, and rate of perceived exertion (RPE) were performed at each stage. EOTS was determined by plotting individual curves for each subject with the energy cost of locomotion as a function of velocity. RESULTS: Preferred transition speed was 7.23 +/- 0.25 and 7.42 +/- 0.25 km.h(-1) for nonrunners and runners, respectively (P > 0.05), and differed significantly (F = 16.47, alpha < 0.001) from the EOTS, which was 8.02 +/- 0.84 km.h(-1) for nonrunners and 7.90 +/- 0.48 km.h(-1) for the runners. No significant differences were found between runners and nonrunners in PTS or EOTS. Running at the PTS resulted in a significantly lower RPE and higher energy cost than walking at the PTS in both groups. CONCLUSION: This study indicates that 1) the preferred PTS is slower than the EOTS, and 2) the PTS and EOTS are not dependent on the aerobic capacity or the training status.

Adult↗

PubMed2007

Estimation of oxygen uptake during fast running using accelerometry and heart rate.

UNLABELLED: Previous investigations have reported that accelerometer counts plateau during running at increasingly faster speeds. PURPOSE: To assess whether biomechanical and/or device limitations cause this phenomenon and the feasibility of generating oxygen uptake (.VO2) prediction equations from the combined use of accelerometry and heart rate during walking and running. METHODS: : Sixteen endurance-trained subjects completed two exercise tests on a treadmill. The first was a continuous incremental test to volitional exhaustion to determine ventilatory threshold and peak .VO2. The second was a discontinuous incremental exercise test while walking (3, 5, and 7 km.h(-1)) and running (8, 10, 12, 14, 16, 18, and 20 km.h(-1), or until volitional exhaustion). Subjects completed 3 min of exercise at each speed, followed by 3-5 min of recovery. Activity counts from uni- and triaxial accelerometers, heart rate, and gas exchange were measured throughout exercise. RESULTS: All accelerometer outputs rose linearly with speed during walking. During running, uniaxial accelerometer outputs plateaued, whereas triaxial output rose linearly with speed up to and including 20 km.h(-1). Prediction of .VO2 during walking and running using heart rate (R2 = 0.42 and 0.59, respectively), accelerometer counts (R2 = 0.48-0.83 and 0.76, respectively), the combined methodologies (R2 = 0.54-0.85 and 0.80, respectively), and the combined methodologies calibrated with individual data (R2 = 0.99-1.00 and 0.99, respectively) was completed by linear regression. CONCLUSIONS: Uni- and triaxial accelerometer outputs have a linear relationship with speed during walking. During running, uniaxial accelerometer outputs plateau because of the biomechanics of running, whereas triaxial accelerometer output has a linear relationship. The combined methodologies predict .VO2 better than either predictor alone; a subject's individually calibrated data further improves .VO2 estimation.

Acceleration↗

PubMed2004

The relationships between local muscular endurance and kinematic changes during a run to exhaustion at vVO2max.

The relationships between local muscular endurance and kinematic changes during a run to exhaustion at vVo2max. J Strength Cond. Res. 18(4):000-000. 2004.-A recent study suggested that runners who maintain a stable running style are able to run for longer at vVo2max velocity (vVo2max). This may be because of the capacity of various muscle groups to maintain their functions despite the onset of fatigue. The purpose of this study was to examine the relationship between local muscular endurance of both the hip and knee extensor and flexor muscle groups and the kinematic changes during a run to exhaustion at vVo2max. Six subelite runners (age 24.2 + 4.2) participated in this study;they were considered as a homogeneous group based upon theirvVo2max scores (coefficient of variation = 3.9%). They performed an incremental protocol to determine vVo2max, a series of isokinetic tests to determine the local muscular endurance of both knee and hip flexors and extensors, and a run to exhaustion at vVo2max. The change in kinematic variables between the beginning and the end of the run were correlated with the measures of muscular endurance. Several statistically significant negative correlations emerged between the change in stride length and concentric hip extension (HE(con)), r = -0.934; eccentric hip extension (HE(ecc)), r = -0.818; eccentric knee flexion(KF(ecc)), r = -0.957; and change in maximum hip extension (Delta max HE), r - -0.857; and Delta max HE with HE(con), r = -0.846.We concluded that the local muscular endurance of both HE(con) and KF(ecc) are important in maintaining a stable running style.

Adult↗

PubMed2001

Habituation contributes to within-session changes in free wheel running.

Three experiments tested the hypothesis that habituation contributes to the regulation of wheel running. Rats ran in a wheel for 30-min sessions. Experiment 1 demonstrated spontaneous recovery. Rats ran more and the within-session decreases in running were smaller after 2 days of wheel deprivation than after 1 day. Experiment 2 demonstrated dishabituation. Running rate increased immediately after the termination of a brief extra event (application of the brake or flashing of the houselight). Experiment 3 demonstrated stimulus specificity. Rats completed the second half of the session in either the same wheel as the first half, or a different wheel. Second-half running was faster in the latter case. Within-session patterns of running were well described by equations that describe data from the habituation, motivation, and operant literatures. These results suggest that habituation contributes to the regulation of running. In fact, habituation provides a better explanation for the termination of wheel running than fatigue, the variable to which this termination is usually attributed. Overall, the present findings are consistent with the proposition that habituation and sensitization contribute to the regulation of several forms of motivated behavior.

Animals↗

PubMed1991

Cardiorespiratory and lactate responses to a 1-hour submaximal running at the lactate threshold.

Cardiorespiratory and blood lactate (La) responses to prolonged submaximal running at an intensity relative to lactate threshold (LT) were examined in 15 recreational runners, aged 19 to 32. In test 1 where treadmill speed was progressively incremented by 10-20m/min until exhaustion, oxygen uptake at the LT (VO2 @ LT: 2.34 +/- 0.331/min or 41.6 +/- 5.7 ml/kg/min) and VO2max (3.58 +/- 0.341/min or 63.6 +/- 5.5 ml/kg/min) were measured. In test 2, the subject was required to run on the treadmill for 1 hour at a fixed velocity (Vt) which corresponded to his Vt @ LT. As expected, mean VO2 ranged during the 1-h submaximal running from 2.31 +/- 0.411/min or 63.0 +/- 7.8% VO2max at min 10-20 to 2.52 +/- 0.351/min or 69.2 +/- 6.2% VO2max at min 50-60, both of which were close to VO2 @ LT (65.2 +/- 4.4% VO2max). The slight decrease in blood La was found from min 20 to min 60, and this was accompanied by a parallel decline in respiratory exchange ratio. Shifts in the energy substrate toward a reliance on fat oxidation may occur during the course of 1-h running at Vt @t LT. The small oxygen debt observed after the 1-h running may confirm the assumption that prolonged running at Vt at LT would be performed in an almost fully aerobic steady state. We conclude that prolonged running at Vt @ LT may possibly maximize health-related benefits in the healthy adult.

Adult↗

PubMed1993

[Cardiorespiratory responses during flume swimming and treadmill running in swimmers].

The present study was designed to compare cardiorespiratory responses of swimmers to swimming and running. Six male trained college swimmers performed maximal work test (progressive method) in flume swimming and treadmill running. VEmax during swimming (128.3 +/- 20.6 l/min) was about 4% lower than during running (133.2 +/- 9.9 l/min). VO2max during swimming (3628 +/- 228 ml/min) was significantly higher than during running (3408 +/- 222 ml/min). HRmax during swimming (191 +/- 8 beats/min) was significantly lower than during running (198 +/- 6 beats/min). VO2 at ventilatory threshold (VT) during swimming (2177 +/- 183 ml/min) was significantly higher than during running (1699 +/- 214 ml/min). %VO2max at VT during swimming (60.1 +/- 4.2%) was significantly about 10% higher than during running (49.8 +/- 4.4%). These results suggest that subjects of this study have specific cardiorespiratory adaptation to swimming from a long period of swim training.

Adult↗

PubMed1992

Biomechanics of sprint running. A review.

Understanding of biomechanical factors in sprint running is useful because of their critical value to performance. Some variables measured in distance running are also important in sprint running. Significant factors include: reaction time, technique, electromyographic (EMG) activity, force production, neural factors and muscle structure. Although various methodologies have been used, results are clear and conclusions can be made. The reaction time of good athletes is short, but it does not correlate with performance levels. Sprint technique has been well analysed during acceleration, constant velocity and deceleration of the velocity curve. At the beginning of the sprint run, it is important to produce great force/power and generate high velocity in the block and acceleration phases. During the constant-speed phase, the events immediately before and during the braking phase are important in increasing explosive force/power and efficiency of movement in the propulsion phase. There are no research results available regarding force production in the sprint-deceleration phase. The EMG activity pattern of the main sprint muscles is described in the literature, but there is a need for research with highly skilled sprinters to better understand the simultaneous operation of many muscles. Skeletal muscle fibre characteristics are related to the selection of talent and the training-induced effects in sprint running. Efficient sprint running requires an optimal combination between the examined biomechanical variables and external factors such as footwear, ground and air resistance. Further research work is needed especially in the area of nervous system, muscles and force and power production during sprint running. Combining these with the measurements of sprinting economy and efficiency more knowledge can be achieved in the near future.

Acceleration↗

PubMed2005

Running performance differences between men and women:an update.

More than a decade ago it was reported in the journal Nature that the slope of improvement in the men's and women's running records, extrapolated from mean running velocity plotted against historical time, would eventually result in a performance intersection of the sexes across a variety of running distances. The first of these intersections was to occur for 42 000 m before the 21st century. Most of the error in this prediction is probably explained by the linear mathematical treatment and extrapolation of limited performance data, since including world record-setting running performances for women before and after 1985 results in a non-linear data fit. The reality of early, disproportionate improvements in women's running that gave the appearance of an impending convergence with men is best explained by an historical social sports bias. Women's times have now reached a plateau similar to that observed for men at comparative performance milestones in the marathon. Sex differences at distances from 100 to 10 000 m show similar trends. The remaining sex gaps in performance appear biological in origin. Success in distance running and sprinting is determined largely by aerobic capacity and muscular strength, respectively. Because men possess a larger aerobic capacity and greater muscular strength, the gap in running performances between men and women is unlikely to narrow naturally.

Adult↗

PubMed1995

Phase relation and breathing pattern during locomotor/respiratory coupling in uphill and downhill running.

Differential effects of uphill and downhill running on phase relation between locomotor and respiratory cycles were studies in nine experienced runners who were instructed to run uphill and downhill on a sloped surface at comfortable and constant speeds (actually 1.7-4.4 m s-1). Timings of footstrike and onsets of inspiration and expiration were measured to compute respiratory cycle duration (Ttot), inspiratory time (Ti), duty cycle (Ti/Ttot), and stride time (Ts). Incidence of locomotor/respiratory coupling (LRC) was determined based on steadiness of Ttot and Ts (within +/- 0.1 s in SD) and Ttot/Ts (LRC ratio, integer or a half-integer multiples). Both in the uphill and downhill running, LRC ratio observed was 1:1, 2:1, and 2.5:1. Ti/Ttot during LRC was 0.41-0.49, which depended on the combinations of Ts and LRC ratio but not on the running conditions. In the uphill running, the onset of inspiration subsequent to footstrike was seen during the first half period (corresponding to the support phase) of the step interval (Ts/2, the time interval between the right and left footstrikes) in 7 of the 9 subjects, while in the downhill running it occurred during the last half period of the step interval (the floating phase) in all subjects. For onset of expiration, no consistent relation to footstrike was observed. These results suggest that the mechanical constraints of running on the respiratory system affect the phase relation between locomotor and respiratory cycles but not Ti/Ttot during LRC.

Adult↗

PubMed2003

Walking and running inter-limb asymmetry for Paralympic trans-femoral amputees, a biomechanical analysis.

The aim of this project was to further the research and understanding of the trans-femoral amputee's ability to walk and run by comparing the changes in walking and running inter-limb asymmetry. An objective biomechanical analysis was conducted on four male transfemoral amputees, all members of the Australian Paralympic training squad for the 1996 Atlanta Paralympic Games. The data was collected in the biomechanics laboratories at Queensland University of Technology and the Australian Institute of Sport. The main outcomes measure a synchronised 3D kinematic (200 Hz), kinetic (600 Hz) and temporal analysis of walking at self-selected (1.1-1.3 m/s), and at maximal running speed (2.5-4.3 m/s). The walking and running biomechanical data was summarised into 27 indices of symmetry. The results showed that for all subjects the inter-limb asymmetry was significantly different at running speed, when compared to the walking speed. Using indices of symmetry 79% of the kinematic, 67% of the kinetic, and 67% of the temporal measurements identified better inter-limb asymmetry when the subjects walked, compared to running. This study objectively identified that when Paralympic level amputees ran on their standard running prosthesis, the inter-limb asymmetry was exacerbated.

Adult↗

PubMed1986

Running patterns of transfemoral amputees: a clinical analysis.

The challenge of rehabilitating young, healthy transfemoral amputees may extend beyond the boundaries of teaching them to adapt to functional activities of daily living. The goal for several of these amputees is to participate and sometimes even compete in recreational activities, including running. These amputee runners require prosthetic adaptations as well as a comprehensive individualized training programme to ensure that their running is as safe and energy efficient as possible. To help amputees achieve this, clinicians must understand normal and prosthetic locomotion. This paper compares the biomechanical differences between walking and running in normal locomotion and analyses the running modes used by transfemoral amputees. The modified running mode achieved with the Terry Fox Running Prosthesis subjectively "looks" more energy efficient to the observer and "feels" more energy efficient to the user. These assumptions have yet to be confirmed or refuted by a rigorous scientific research study. An outline of the proposed physiotherapy protocol includes the familiarization, treatment, and training phases. Physiotherapists involved in amputation rehabilitation may not be commonly confronted with this level of patient expectation. It is their responsibility to give realistic guidance to these amputees so that they can safely and independently pursue their recreational running activities. This need can best be fulfilled by providing sound clinical advice which has been validated by research findings.

Amputation, Surgical↗

PubMed2006

Walking and running on the circular treadmill: transition speed and podokinetic aftereffects.

The author compared 10 participants' self-selected walk-to-run transition speeds on a standard treadmill with those on a circular treadmill. The speed of the outer limb at walk-to-run transition on the circular treadmill and on the standard treadmill were very similar. Adaptive aftereffects from running and walking on the circular treadmill were also similar. When asked to step in place without vision, all participants inadvertently turned in circles following walking or running on the treadmill. The results of the present study suggest that the mechanisms controlling walk-to-run transitions are similar for the standard and circular treadmills and demonstrate the robust generalizability of locomotor aftereffects from running to walking. Adaptive control of speed, form, and direction may therefore share similar mechanisms for walking and running.

Adult↗

PubMed2001

Duration and seriousness of running mechanics alterations after maximal cycling in triathletes. Influence of the performance level.

BACKGROUND: Non-experienced triathletes use to complain about the difficulty to run after cycling. We tested the hypothesis that elite triathletes have lower and/or shorter alterations in running mechanics following a maximal cycling exercise than their less efficient counterparts. METHODS: The mechanical alterations in running after exhaustive cycling exercise were studied in eight elite (E) and 18 middle-level (M) triathletes. Before and after maximal cycling exercise, the subjects completed two 7-min runs on a treadmill at a velocity corresponding to that sustained during a triathlon. External mechanical cost was quantified during the first and last minute of each run from displacements of the centre of mass using a kinematic arm. RESULTS: The effect of cycling on the potential, kinetic and mechanical costs (respectively, 7.1+/-6.0% and 0.4+/-6.9% increase for M and E) during the first minute of running appeared to be more adverse (p<0.05) for M than E. The mechanical changes between pre- and postcycling exercise were similar among the two groups at the 6th minute, suggesting that the mechanical alterations due to a cycling fatigue in M are brief. CONCLUSIONS: Since the needs to run efficiently immediately after cycling are associated with performance in triathlon, the results of the present study have practical implications for training.

Bicycling↗

PubMed2001

DLCO response to experimental cycle-run succession in triathletes.

BACKGROUND: We still know relatively little about the factors that define the ability to perform a good run after cycling in triathlon, however, and the perception of discomfort during the first minutes of this post-cycling running has yet to be satisfactorily explained. The pulmonary diffusion capacity for carbon monoxide (DLCO) has been demonstrated to be impaired after the cycle-run succession. Numerous causes have been suggested to explain this phenomenon, but the exact mechanism has not yet been determined. METHODS: Thirteen young male triathletes participated in four different exercise trials: 30 min of cycling followed by 20 min of running (C-R, 1 min rest between C and R), 30 min of running followed by 20 min of running (R-R, 1 min rest between R and R), 30 min of cycling (C), and 30 min of running (R). DLCO and alveolar volume were simultaneously measured during 9 sec of breath-holding before and 10 min after exercise. The transfer coefficient (KCO=DLCO/VA) was then calculated. During all trials, ventilatory data were collected every minute using an automated breath-by-breath system. RESULTS: The results showed that 1) C-R and C induced significant and identical decreases in DLCO and KCO in post-trial compared with pre-trial measurement (40.41+/-2.24 vs 43.49+/-2.36 ml x min(-1) x mm Hg(-1), p<0.01, and 39.37+/-2.16 vs 42.99+/-2.38 ml x min(-1) x mm Hg(-1), p<0.02, for C-R and C, respectively) and 2) there were no DLCO decreases in post-trial compared with pre-trial measurement in R-R and R. CONCLUSIONS: We concluded that cycling exercise in itself seems to increase the immediate post-exercise DLCO impairment.

Adult↗

PubMed1976

Energy cost of running and walking in young women.

The energy cost of level walking and level and grade running was determined in 7 active women with max VO2 = 50.7 ml/kg-min. Speeds investigated were 4 to 8 km/hr walking and 8 to 14.5 km/hr running. The validity coefficients of several procedures for estimating energy expenditure during locomotion [4 for running (6)(11)(16)(17); 3 for walking (6)(12)(17)] were determined. Correlation coefficients between actual and predicted values were 0.949 to 0.951 with standard errors of estimate 0.79 to 0.80 kcal/kg-hour for walking and 0.856 to 0.975 with standard errors of estimate 0.40 to 0.60 kcal/kg-hour for running. VO2 and kcal energy cost values were similar to those previously reported on men at equivalent walking and running speeds. Efficiency of running based on lift work done was about 25%. Lift work for women was slightly less than values previously reported for men at walking but was slightly more at running. These differences did not appear to have a significant effect on energy expenditure.

Energy Metabolism↗

PubMed2003

Postural control after a 2-mile run.

Postural control is essential for normal daily activities. It is also a crucial requirement for athletic events and activities. Deterioration in this postural control mechanism is termed postural instability and results in increased postural sway. Decrements in postural sway have been documented following a 15.5-mile run. It remains to be seen whether a shorter distance run will cause a similar decrease in postural control. Therefore, the purpose of this study was to assess the effects of a 2-mile run on postural sway in healthy subjects. Forty-four healthy subjects were assigned to an experimental group (2-mile run) or a control group. Postural sway was measured before and after the run with the Biodex Stability System Overall Stability Index and a clinical balance test called the Military Academy Stance Test. There was a significant before-after run Biodex Stability System Overall Stability Index (p < 0.05) and Military Academy Stance Test index (p < 0.05) increase in the experimental group. There was no significant change for the control group. It was concluded that a 2-mile run does produce a significant increase in postural sway as measured using the Biodex Stability System Overall Stability Index and Military Academy Stance Test.

Adult↗