SEARCH · PubMed Health

Results for “Running”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 235 records · Page 13Linked to original sources

PubMed2000

Running and cocaine both upregulate dynorphin mRNA in medial caudate putamen.

Physical activities such as long-distance running can be habit forming and associated with a sense of well-being to a degree that justifies comparison with drug-induced addictive behaviours. To understand molecular similarities and dissimilarities controlling these behaviours in humans we compared the effects of running in running wheels to the effects of chronic cocaine or morphine administration on mRNA levels in brain reward pathways in the inbred Fischer and Lewis rat strains. These strains are both inbred from the Sprague-Dawley strain; Lewis rats display a higher preference towards addictive drugs and running than do Fischer rats. After chronic cocaine or running a similar increase of dynorphin mRNA in medial caudate putamen was found in the Lewis rat, suggesting common neuronal adaptations in this brain region to both cocaine and running. Fischer and Lewis rats both responded to cocaine with increased dynorphin mRNA levels in medial caudate putamen. However, only Lewis rats increased dynorphin mRNA after running, possibly reflecting the much higher degree of running by the Lewis strain as compared to the Fischer strain. Moreover, the running-induced upregulation of dynorphin mRNA was blocked by the opioid receptor antagonist naloxone. We suggest that running increases dynorphin mRNA by a mechanism that involves endogenous opioids. The voluntary wheel-running model in rats might be used to study natural reward and compulsive behaviours and possibly also to screen candidate drugs for treatment of compulsive disorders.

Analgesics, Opioid↗

PubMed2006

Influence of pacing strategy on oxygen uptake during treadmill middle-distance running.

The oxygen uptake (VO2) attained during a constant speed 800-m pace trial on a treadmill is less than the maximal VO2 (VO2max) in male middle-distance runners with a high VO2max (i.e., > 65 ml x kg (-1) x min (-1)). We therefore investigated whether the VO2 attained was influenced by the pacing strategy adopted. Eight male middle-distance runners (age 25.8 +/- 3.3 years; height 1.78 +/- 0.10 m; mass 67.8 +/- 4.7 kg) with a personal best 800-m time of 112.0 +/- 3.3 s volunteered to participate. Subjects undertook a speed ramped progressive test to determine VO2max and three 800-m pace runs to exhaustion all in a randomised order. The three 800-m pace runs included constant speed, acceleration, and race simulation runs. Oxygen uptake was determined throughout each test using 15-s Douglas bag collections. Following the application of a 30-s rolling average, the highest VO2 during the progressive test (i.e., VO2max) and the highest VO2 during the 800-m pace runs (i.e., VO2peak) were compared. For the eight runners, VO2max was 67.2 +/- 4.3 ml x kg (-1) x min (-1) x VO2peak was 60.1 +/- 5.1 ml x kg (-1) x min (-1), 61.1 +/- 5.2 ml x kg (-1) x min (-1), and 62.2 +/- 4.9 ml x kg (-1) x min (-1), yielding values of 89.3 +/- 2.4 %, 90.8 +/- 2.8 %, and 92.5 +/- 3.1 % VO2max for the constant speed, acceleration and race simulation runs, respectively. Across runs, repeated measures ANOVA revealed a significant effect (p = 0.048). Trend analysis identified a significant linear trend (p = 0.025) with the % VO2max attained being higher for the acceleration run than the constant speed run, and higher still for the race simulation run. These results demonstrate that in middle-distance runners a) pacing strategy influences the VO2 attained, with a race simulation run elevating the VO2 attained compared with other pacing strategies, and b) regardless of pacing strategy the VO2 attained in an 800-m pace run on a treadmill is less than VO2max.

Acceleration↗

PubMed1998

Kinematics and electromyography of lower limb muscles in overground and treadmill running.

Treadmills are often used in research to analyse kinematic and physiological variables. The success of transfering the results to overground running depends on the comparability of the values between the two situations. The aim of the present study was to compare the kinematics and muscle activities in overground and treadmill running. Ten male physical education students with experience in treadmill running were asked to run with a speed of 4.0 and 6.0 m/s both overground and on a Woodway treadmill. The 3D-kinematics of the limbs were studied using a two camera video tracking system. Additionally the surface EMG of six lower limb muscles and the pattern of ground contact of the right foot was registered. Both the activities of the leg muscles and several kinematic variables showed systematic changes from overground to treadmill running. On the treadmill the subjects favoured a type of running that provided them with a higher level of security. The swing amplitude of the leg, the vertical displacement and the variance in vertical and horizontal velocity were lower in treadmill running. The angle between shoe sole and ground at foot impact was also lower and the forward lean of the upper body was higher in running on the treadmill compared with the overground mode. Most of the subjects reduced their step length and increased stride frequency in treadmill running. Furthermore, the contact time in treadmill running was shorter than for overground running. The above mentioned kinematic variables were significantly different (p < 0.05). The EMG patterns of the leg muscles were generally similar between overground and treadmill modes, but some minor differences could consistently be identified.

Adult↗

PubMed2005

Effects of adding a preceding run-up on performance, blood lactate concentration and heart rate during maximal intermittent vertical jumping.

In this study, we examined the effects of a prior run-up on intermittent maximal vertical jump performance. Seven regionally ranked male volleyball players volunteered to participate in the study. They performed three randomized tests: (1) six repeated intermittent maximal jumps (jump condition), (2) six repeated intermittent run-ups (run-up condition), and (3) six repeated run-ups followed by maximal jumps (run-up plus jump condition). All performances were assessed and blood lactate concentration and heart rate were measured before and after each of the tests. Mean ( +/- ) jump performance (64.7 +/- 2.3 cm) increased significantly (P = 0.02) over the course of the jump condition and was significantly higher (P < 0.001) than for the run-up plus jump condition (58.0 +/- 3.2 cm), which tended to decrease with repetition. Blood lactate concentration was significantly higher in the run-up plus jump condition (3.73 +/- 0.24 mmol . l(-1)) than in the jump (2.61 +/- 0.26 mmol . l(-1), P = 0.02) and run-up (2.86 +/- 0.18 mmol . l(-1), P = 0.03) conditions. The increase in heart rate was significantly higher both in the run-up plus jump condition (33 +/- 6 beats . min(-1), P = 0.05) and run-up condition (33 +/- 4 beats . min(-1), P = 0.02) than in the jump condition (21 +/- 3 beats . min(-1)). The results indicate that the addition of run-ups probably impeded performance in the repetition of vertical jumps.

Adaptation, Physiological↗

PubMed2006

Moderate-domain pulmonary oxygen uptake kinetics and endurance running performance.

The aims of this study were to determine if the primary time constant (tau) for oxygen uptake (VO2) at the onset of moderate-intensity treadmill exercise is related to endurance running performance, and to establish if tau could be considered a determinant of endurance running performance. Thirty-six endurance trained male runners performed a series of laboratory tests, on separate days, to determine maximal oxygen uptake (VO2max), the ventilatory threshold (VT) and running economy. In addition, runners completed six transitions from walking (4 km x h-1) to moderate-intensity running (80% VT) for the determination of the VO2 primary time constant and mean response time. During all tests, pulmonary gas-exchange was measured breath-by-breath. Endurance running performance was determined using a treadmill 5-km time-trial, after which runners were considered as combined performers (n=36) and, using a ranking system, high performers (n=10) and low performers (n=10). Relationships between tau and endurance running performance were quantified using correlation coefficients (r). Stepwise multiple regression was used to determine the primary predictor variables of endurance running performance in combined performers. Moderate correlations were observed between tau, mean response time and endurance running performance, but only for the combined performers (r=-0.55, P=0.001 and r=-0.50, P=0.002, respectively). The regression model for predicting 5-km performance did not include tau or mean response time. The velocity at VO2max was strongly correlated to endurance running performance in all groups (r=0.72 - 0.84, P < 0.01) and contributed substantially to the prediction of performance. In conclusion, the results suggest that despite their role in determining the oxygen deficit and having a moderate relationship with endurance running performance, neither tau nor mean response time is a primary determinant of endurance running performance.

Adult↗

PubMed1999

Economy in track runners and orienteers during path and terrain running.

The aims of the present study were to assess running economy in track runners and orienteers and to identify the factors responsible for any differences. The participants were 11 orienteers and 10 track runners of similar age, body mass, maximal oxygen uptake and training background. However, the orienteers included heavy terrain running in their daily training, whereas the track runners ran almost entirely on the roads and tracks. Maximal oxygen uptake and running economy were calculated during horizontal path running and during cross-country running in rough terrain with steep hills, using a telemetric system (K2, Cosmed, Italy). Running economy during path running was 217+/-12 and 212+/-14 ml x kg(-1) x km(-1) (mean +/- s) in the orienteers and the track runners, respectively. Running economy was impaired by 41-52% in heavy terrain (P < 0.05), and was less pronounced in the orienteers than in the track runners (88+/-18 vs 109+/-26 ml x kg(-1) x km(-1); P < 0.05). In conclusion, the better running economy of orienteers when changing from horizontal path to heavy terrain running could be an innate ability, or it could be speculated that specific training may improve running economy, indicating the importance of specific training for orienteers.

Adult↗

PubMed2001

Validity of motor tasks for predicting running ability in acquired brain injury.

INTRODUCTION: Rehabilitation of running following traumatic brain injury (TBI) has the potential to enhance quality of life. Retraining of running following TBI has not been previously reported in the literature. In response to a lack of information about which motor tasks should be included in a retraining programme, this study aimed to investigate performance predictors of running ability. METHOD: Forty TBI subjects (20 runners and 20 non-runners) performed four specific motor tasks which were selected on the basis of theory and clinical experience with TBI subjects. The four tasks included bounding onto a leg, walking on toes, stepping backwards up a step, and balancing on one leg. Subjects were generally extremely severely brain damaged (median post-traumatic amnesia >28 days), had suffered multiple leg fractures and had received greater than 8 months rehabilitation. RESULTS: The four motor tasks differentiated significantly between the two groups (p < 0.001) and were all strong predictors of running ability. The presence of a non-support phase (NSP) during the bounding task was the strongest predictor of running ability. Logistic regression indicated that TBI subjects who could execute a NSP into a single bound were 24.6 times more likely to be able to run than subjects who could not. When the four tasks were used in combination, two tasks were identified by logistic regression: (1) ability to execute a free-float phase during a bound, and (2) balancing on one leg. All four motor tasks had high retest reliability, with proportional indices of reliability ranging from 0.92-0.97. No statistically significant difference was found between runners and non-runners for group characteristics such as age, severity of injury (length of PTA), orthopaedic leg injuries and time post-injury (p > 0.05). These characteristics were not shown to influence the ability to run following TBI. CLINICAL IMPLICATIONS: The four motor tasks were strong predictors of running ability. Severity and type of injury were not factors influencing ability to run. This study provides preliminary evidence about the motor tasks which have the potential to be used in a running programme. No casual relationship has been identified. The next step is to investigate whether training in these tasks is effective in the rehabilitation of running following TBI.

Adult↗

PubMed2001

Running mileage, movement mileage, and fitness in male U.S. Navy recruits.

PURPOSE: The purpose of this study was to determine whether there is a relationship between overall fitness improvement and varying amounts of running and movement mileage. METHODS: Subjects were male U.S. Navy recruits (N = 1703, 25 divisions), ages 17-35 yr (mean age = 20.1 +/- 2.9 yr), who attended boot camp from April 1996 through August 1996. During the first week of training, recruits performed a 1.5-mile run to determine baseline fitness levels. The results from the initial run were compared with a final 1.5-mile run conducted 6 wk later. RESULTS: Based on an age-adjusted fitness scale for a 1.5-mile run time, about one third of the recruits began recruit training in "Excellent-Superior" condition (N = 558), one third began in "Good" condition (N = 582), and one third began in "Poor-Fair" condition (N = 563). Running mileage among divisions ranged from 11.5 to 43.5 miles for the entire 7-wk training period (mean = 22.7 +/- 7.2 miles; 8-22 run days, mean = 13 +/- 4 d). In addition to running, the divisions accumulated many movement miles (110-202 miles; mean = 145 +/- 26 miles) while marching in formation. Recruits who began training in Poor-Fair condition improved the most with an average decrease in run time of 1:55 +/- 1:06 min (15.6% improvement). The Good group improved by 47 +/- 37 s (7.3% improvement), and the Excellent-Superior group improved by 17 +/- 32 s (2.9% improvement). CONCLUSION: The magnitude of fitness improvement, as measured by run time improvement, was directly related to baseline fitness level but not related to movement mileage or high-intensity run mileage accrued during training.

Adolescent↗

PubMed2004

Different frequency treadmill running in immobilization-induced muscle atrophy and ankle joint contracture of rats.

We investigated the effects of different frequencies of treadmill running on immobilization-induced soleus and gastrocnemius muscle atrophy and ankle joint contracture in rats using morphology and histochemistry. The right ankle joint of rat was immobilized for 2 weeks. Thereafter, the rats were randomly assigned to four groups for 6 weeks of exercise under different conditions: free cage activity and free remobilization (FR), once-a-week treadmill running (low-frequency running program (LFR)), three-time-a-week running (middle-frequency running program (MFR)), and six-time-a-week running (high-frequency running program (HFR)) groups. Two weeks of immobilization significantly reduced the cross-sectional area of soleus type I (62%, P<0.05) and type II muscle fibers (66%, P<0.05), gastrocnemius type I (78%, P<0.05) and type II muscle fibers (68%, P<0.05), and the range of ankle joint movement (46%, P<0.05). Immobilization also increased the ratio of type II to total fiber numbers in the soleus (P<0.05), and gastrocnemius (P<0.05), and induced pathological changes in muscle fibers. Some of these changes could not be corrected by free remobilization; however, the LFR, MFR, and HFR groups clearly recovered toward normal levels with exercise frequency, the effect on muscle recovery being more beneficial in the MFR and HFR groups. In addition, the range of ankle joint contracture was improved in LFR, MFR, and HFR groups in comparison with that in the FR group. These findings indicate that treadmill running exercise improved the immobilization-induced muscle fiber histochemical alterations and the range of the ankle motion in rats. Running three times and six times a week was more beneficial for recovery of immobilization-induced muscle atrophy and joint contracture compared with no running or once-a-week running.

Animals↗

PubMed2002

Critical velocity and time spent at a high level of VO2 for short intermittent runs at supramaximal velocities.

This study was designed to determine the intermittent critical velocity, the time spent at maximal oxygen uptake (VO2max) and the time spent above 90% of VO2max for short intermittent runs of 15 s at supramaximal velocities, alternating with 15 s of passive recovery. Nine male subjects performed 5 field-tests to exhaustion (tlim): 4 intermittent runs at 110%, 120%, 130% and 140% of maximal aerobic speed (MAS) and 1 continuous run at 100% of MAS. Results have shown the mean intermittent critical velocity (4.82 +/- 0.41 m.s-1) was not significantly different from MAS (4.63 +/- 0.37 m.s-1). Intermittent runs at 110% and 120% of MAS and the continuous run at 100% of MAS lead all subjects to reach VO2max. However, intermittent runs at 120% of MAS (202 +/- 66 s) allowed subjects to spend a significantly longer time at VO2max (p < .05) than intermittent runs at 110% (116 +/- 42 s), 130% (50 +/- 47 s), 140% (48 +/- 59 s) of MAS and continuous run at 100% of MAS (120 +/- 42 s). The time spent between 90 and 100% of VO2max was significantly longer (p < .05) for intermittent runs at 110% (383 +/- 180 s) and for 120% (323 +/- 272 s) of MAS than for intermittent runs at 130% (135 +/- 133 s), 140% of MAS (77 +/- 96 s) and for continuous run at 100% of MAS (217 +/- 114 s). Consequently, this kind of intermittent exercise with intensities from intermittent critical velocity to 120% of MAS could be introduced in a training program when the purpose is to increase VO2max.

Adult↗

PubMed1997

Lower extremity muscle activation during horizontal and uphill running.

To provide more comprehensive information on the extent and pattern of muscle activation during running, we determined lower extremity muscle activation by using exercise-induced contrast shifts in magnetic resonance (MR) images during horizontal and uphill high-intensity (115% of peak oxygen uptake) running to exhaustion (2.0-3.9 min) in 12 young women. The mean percentage of muscle volume activated in the right lower extremity was significantly (P <0.05) greater during uphill (73 +/- 7%) than during horizontal (67 +/- 8%) running. The percentage of 13 individual muscles or groups activated varied from 41 to 90% during horizontal running and from 44 to 83% during uphill running. During horizontal running, the muscles or groups most activated were the adductors (90 +/- 5%), semitendinosus (86 +/- 13%), gracilis (76 +/- 20%), biceps femoris (76 +/- 12%), and semimembranosus (75 +/- 12%). During uphill running, the muscles most activated were the adductors (83 +/- 8%), biceps femoris (79 +/- 7%), gluteal group (79 +/- 11%), gastrocnemius (76 +/- 15%), and vastus group (75 +/- 13%). Compared with horizontal running, uphill running required considerably greater activation of the vastus group (23%) and soleus (14%) and less activation of the rectus femoris (29%), gracilis (18%), and semitendinosus (17%). We conclude that during high-intensity horizontal and uphill running to exhaustion, lasting 2-3 min, muscles of the lower extremity are not maximally activated, suggesting there is a limit to the extent to which additional muscle mass recruitment can be utilized to meet the demand for force and energy. Greater total muscle activation during exhaustive uphill than during horizontal running is achieved through an altered pattern of muscle activation that involves increased use of some muscles and less use of others.

Adult↗

PubMed2005

Mechanical and morphological properties of different muscle-tendon units in the lower extremity and running mechanics: effect of aging and physical activity.

The objectives of this work were (i) to investigate whether chronic endurance running is a sufficient stimulus to counteract the age-related changes in the mechanical and morphological properties of human triceps surae (TS) and quadriceps femoris (QF) muscle-tendon units (MTUs) by comparing runners and non-active subjects at different ages (young and old), (ii) to identify adaptational phenomena in running mechanics due to age-related changes in the mechanical and morphological properties of the TS and QF MTUs, and finally (iii) to examine whether chronic endurance-running exercise is associated with adaptational effects on running characteristics in old and young adults. The investigation was conducted on 30 old and 19 young adult males divided into two subgroups according to their running activity: endurance-runners vs non-active. To analyse the properties of the MTUs, all subjects performed isometric maximal voluntary (MVC) ankle plantarflexion and knee extension contractions at 11 different MTU lengths on a dynamometer. The activation of the TS and QF during MVC was estimated by surface electromyography. The gastrocnemius medialis and the vastus lateralis and their distal aponeuroses were visualized by ultrasonography at rest and during MVC, respectively. Ground reaction forces and kinematic data were recorded during running trials at 2.7 m s(-1). The TS and QF MTU capacities were reduced with aging (lower muscle strength and lower tendon stiffness). Runners and non-active subjects had similar MTU properties, suggesting that chronic endurance-running exercise does not counteract the age-related degeneration of the MTUs. Runners showed a higher mechanical advantage for the QF MTU while running (lower gear ratio) compared to non-active subjects, indicating a task-specific adaptation even at old age. Older adults reacted to the reduced capacities of their MTUs by increasing running safety (higher duty factor, lower flight time) and benefitting from a mechanical advantage for the TS MTU, lower rate of force generation and force generation per meter distance. We suggest that the improvement in running mechanics in the older adults happens due to a perceptual motor recalibration and a feed-forward adaptation of the motor task aimed at decreasing the disparity between the reduced capacity of the MTUs and the running effort.

Adult↗

PubMed1985

Aerobic requirements of overground versus treadmill running.

There is general agreement that the oxygen demand of level running is similar for both the treadmill (TM) and overground situations at speeds under 260 m X min-1. However, controversy exists with regard to inclined running. The prevailing view, represented by the ACSM prediction formulas, is that overground hill running is theoretically more costly than inclined treadmill running. This study was designed to investigate the problem from an empirical standpoint. Seven male subjects performed overground and TM running at two grades (0 and 5.7%) over a range of speeds between 136-286 m X min-1. For the outdoor trials, subjects covered a distance of 950 m at a constant pace, and expired gas was collected over the last 150 m. Matching trials were then performed on the treadmill at the same speed and % grade. Regression lines were calculated for speed vs oxygen consumption (VO2). For TM and overground level running, these were: VO2 (ml.kg-1.min-1)= 0.222 X speed (m.min-1) - 1.33 and VO2 (ml.kg-1.min-1) = 0.202 X speed (m.min-1) + 3.21 respectively. The regression lines from TM and overground inclined running were: VO2 (ml.kg-1.min-1) = 0.237 X speed (m.min-1) + 7.53. and VO2 (ml.kg-1.min-1) = 0.233 X speed (m.min-1) + 7.78 respectively. A 2 X 3 X 2 ANOVA revealed that the differences between mean values for VO2 for level TM running vs level overground running and grade TM running vs grade overground running were not statistically significant (0.10 less than P less than 0.25).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

Patellofemoral joint compressive forces in forward and backward running.

The use of backward running is becoming more common in the rehabilitation setting. In particular, backward running has been suggested as a treatment modality in patients experiencing patellofemoral pain syndrome. To date, no study has examined the loads at the patellofemoral joint during backward running. The purpose of this study was to compare patellofemoral joint compressive forces during forward and backward running. Ground reaction force and kinematic data were collected on five male joggers during free speed forward and backward running. A floor reaction force vector model was used to calculate the stance phase knee extension moments. The distance used for the extensor muscle lever arm was 4.9 cm. Patellar mechanism angle was calculated based on knee joint angle. There was a reduction in the peak patellofemoral joint compressive forces in backward compared with forward running (2277 +/- 192N vs. 4253 +/- 1292N; p < 0.05) at self-selected speeds. Peak patellofemoral joint compressive force occurred significantly later (p < 0.05) in the stance phase of backward running (52 +/- 4%) than in forward running (35 +/- 3%). The peak patellofemoral joint compressive force normalized to subject body weight was 5.6 +/- 1.3 body weight in forward running and 3.0 +/- 0.6 body weight in backward running. The results suggest that backward running at a self-selected speed may reduce patellofemoral joint compressive forces and, coupled with the quadriceps strengthening that has previously been reported, may be beneficial in the rehabilitation of patellofemoral pain syndrome in runners. However, constant speed comparisons or other models may yield different results.

Adult↗

PubMed2003

Effects of running, static stretching and practice jumps on explosive force production and jumping performance.

AIM: The interaction between running, stretching and practice jumps during warm-up for jumping tests has not been investigated. The purpose of the present study was to compare the effects of running, static stretching of the leg extensors and practice jumps on explosive force production and jumping performance. METHODS: Sixteen volunteers (13 male and 3 female) participated in five different warm-ups in a randomised order prior to the performance of two jumping tests. The warm-ups were control, 4 min run, static stretch, run + stretch, and run + stretch + practice jumps. After a 2 min rest, a concentric jump and a drop jump were performed, which yielded 6 variables expressing fast force production and jumping performance of the leg extensor muscles (concentric jump height, peak force, rate of force developed, drop jump height, contact time and height/time). RESULTS: Generally the stretching warm-up produced the lowest values and the run or run + stretch + jumps warm-ups produced the highest values of explosive force production. There were no significant differences (p<0.05) between the control and run + stretch warm-ups, whereas the run yielded significantly better scores than the run + stretch warm-up for drop jump height (3.2%), concentric jump height (3.4%) and peak concentric force (2.7%) and rate of force developed (15.4%). CONCLUSION: The results indicated that submaximum running and practice jumps had a positive effect whereas static stretching had a negative influence on explosive force and jumping performance. It was suggested that an alternative for static stretching should be considered in warm-ups prior to power activities.

Adult↗

PubMed2003

Maximal but not submaximal performance is reduced by constant-speed 10-km run.

AIM: Effects of endurance exercise on running economy, mechanics, force generating capacity and their interactions were examined. During the exercise, metabolic, kinetic and kinematic variables were recorded to find out adaptive mechanisms in the course of the fatiguing run. In addition, before and after it maximal force and power production was tested. METHODS EXPERIMENTAL DESIGN: comparative. SETTING: University. PARTICIPANTS AND INTERVENTION: 7 men unaccustomed to endurance training run 10 km at individually chosen constant speed (3.5+/-0.5 m x s(-1)) on an indoor track. MEASURES: 3-D ground reaction forces, electromyographic (EMG) activities from 7 leg muscles, pulmonary ventilation, gas exchange, heart rate and movement kinematics were measured during the run. Blood lactate and serum creatine kinase activity were determined. Maximal voluntary contraction (MVC) with superimposed double twitch (DT), and passive DT tests in plantarflexor muscles were performed before and after the 10 km run. Changes in 20 m sprint performance were evaluated in before-after comparison. RESULTS: The 10 km run caused significant reductions in maximal running speed (8.2 vs 7.6 m x s(-1), p<0.05), in MVC (1216 vs. 984 N, p<0.05), and in passive DT (271 vs 211 N, p<0.05). During the submaximal run, however, the subjects were able to maintain relatively constant oxygen consumption and running kinematics. Greatest changes in EMG activity and kinetics were seen during the first 2 km. CONCLUSION: After initial adjustment, the runners are able to maintain submaximal running speed with very little changes in running economy, kinetics and kinematics. However, fatigue-induced impairment in the force generating capacity of the contractile component can be revealed by tests measuring maximum performance.

Adult↗

PubMed1992

Running economy: changes with age during childhood and adolescence.

The purpose of this study was to synthesize work directed at describing and understanding changes in running economy (the steady-state demand for oxygen at a set running speed) that occur with increased age during childhood and adolescence. Although the data are limited, a number of tentative conclusions were drawn. Children are less economical than adults. Running economy improves steadily with age in normally active children and adolescents, even in the absence of formal running training. Running economy in later childhood fails to respond to either short-term instruction on the techniques of running or short-term participation in running training. Long-term participation in running training may augment improvements in running economy that occur naturally with age. In a group of heterogeneous subjects of the same age, running economy is not strongly related to performance. Within a subject over a period of years, running economy is strongly related to performance. Children are less economical than adults because when compared with adults, children exhibit (a) higher resting metabolic rates, (b) greater ventilatory equivalents for oxygen, and (c) disadvantageous stride rates and stride lengths.

Adolescent↗

PubMed1990

Physiologic and perceptual responses during treadmill running with ankle weights.

This study examined the effects of ankle weighting on physiologic and perceptual responses during treadmill running in seven healthy, female recreational runners with a mean maximal aerobic power of 48.4 +/- 4.0 ml/kg/min. Each subject completed four experimental one-mile runs at individually selected treadmill running speeds with 0, 1.6, 3.2 and 4.8 kg weights on their ankles. The subjects selected a speed at which they would run (train) if their objectives were to significantly improve cardiovascular function and induce weight loss. Metabolic and cardiovascular responses were continuously monitored, and ratings of perceived exertion were recorded near the end of the activity. During the unweighted run, the subjects selected a running speed of 6.87 +/- 0.63 mph which resulted in a net energy expenditure of 0.153 kcal/kg/min or 1.34 +/- 0.16 kcal/kg/mile. This corresponded to a training intensity of 76.3% +/- 5.1% of maximum oxygen consumption or 88.1% +/- 9.7% of maximum heart rate. Addition of weight to the ankles caused a significant decrease (p less than .05) in the running speed selected and, therefore, did not result in any significant changes (p greater than .05) in the rate of oxygen consumption, heart rate or ratings of perceived exertion when compared to the unweighted condition. These observations are in contrast to previous studies on ankle weighting which were conducted at fixed treadmill running speeds. However, the use of ankle weights did have a tendency to increase gross and net energy expenditure of running when values were expressed in kcal/mile because of slower self-selected running speeds under these conditions. This increase in energy expenditure could be of physiologic significance if running with ankle weights was performed on a regular basis at a fixed distance.

Adult↗