Fenitrothion, an organophosphate, affects running endurance but not aerobic capacity in fat-tailed dunnarts (Sminthopsis crassicaudata)

We measured aerobic metabolism during cold exposure and exercise performance (run duration and oxygen consumption while running at 1 m s⁻¹) in the fat-tailed dunnart Sminthopsis crassicaudata, a dasyurid marsupial, before and after ingestion of 30 mg kg⁻¹ of fenitrothion, an organophosphate (OP) pesticide. Running endurance of OP-exposed animals was less than half that of control animals over the first 3 days after dosing and 55% of control animal endurance on day 5 post-dose. Despite these declines, peak metabolic rate at this running speed (9.3 times basal metabolic rate; BMR) was unaffected by OP exposure. Peak metabolic rate (PMR) and cumulative oxygen consumption during a 1-h exposure to conditions equivalent to −20 °C did not differ between OP-treated and control dunnarts, with PMR averaging 11 times BMR. We conclude that fenitrothion-induced exercise fatigue is not due to limitations in oxygen or substrate delivery to muscle or in their uptake per se, but more likely relates to decreased ability to sustain high-frequency neuromuscular function. The persistence of locomotor impairment following OP exposure in otherwise asymptomatic animals emphasizes the importance of using performance-based measures when characterising sublethal effects of pesticide exposure in an ecological context.

Slow component of VO2 during level and uphill treadmill running : relationship to aerobic fitness in endurance runners

The aim of this study was to compare the oxygen uptake (VO^sub 2^) slow component (SC) during level and uphill running in endurance runners, and to identify associations between the SC and the following aerobic fitness indicators: peak VO^sub 2^, running speed associated with the peak VO^sub 2^ (Vpeak), running speed at the lactic threshold and the VO^sub 2^ fraction elicited at the lactic threshold. Fourteen male endurance-trained runners underwent several 6-min bouts of level (LTR) and 10.5% uphill treadmill running. VO^sub 2^ SC was calculated as the difference between mean VO^sub 2^ during the 6th and the 3rd minutes. The highest mean values for the SC were 181.9±240.2 mL*min^sup -1^ for level running at ~94% peak VO^sub 2^ and 105.4±154.6 mL*min^sup -1^ for uphill running at ~90% peak VO^sub 2^. The SC observed during the last bout of the LTR correlated with peak VO^sub 2^ and with Vpeak (-0.71 and -0.76, P<0.05, respectively). The results show that for endurance-trained runners the magnitude of the SC is not affected by the treadmill gradient and that within a homogeneous sample of endurance-trained runners the SC does not correlate with indicators of aerobic fitness.

The running lie

The thesis consists of a novel entitled, The Running Lie, and an exegesis of 10,000 words. The novel is based on themes of maturation and homosexuality.

Running

Walk down a lane continuously. The film tries to destroy time by the cyclical reworking of a short period of time. Gradually the image becomes less discernible and the flashing positive and negative images force the viewer to stare rather than looking at the film. As the film progresses the viewer becomes trapped in a short period of time.

Running a Cartel? Go directly to jail

Operators of cartels now face not only big fines, but also time in jail. And new laws criminalising cartels leave no room to move.

Running on empty : 'modernising' the British and Australian labour parties

Australia's cultural cringe towards Britan does not just focus on the monarchy. Many in the ALP and the media pay undue deference to Tony Blair's so-called new Third Way. This book shows why the ALP needs to reassess its own history and examines the complex reality of how it compaes with the British Labor Party.

Neuromuscular control and running economy is preserved in elite international triathletes after cycling

Running is the most important discipline for Olympic triathlon success. However, cycling impairs running muscle recruitment and performance in some highly trained triathletes; though it is not known if this occurs in elite international triathletes. The purpose of this study was to investigate the effect of cycling in two different protocols on running economy and neuromuscular control in elite international triathletes. Muscle recruitment and sagittal plane joint angles of the left lower extremity and running economy were compared between control (no preceding cycle) and transition (preceded by cycling) runs for two different cycle protocols (20-minute low-intensity and 50-minute high-intensity cycles) in seven elite international triathletes. Muscle recruitment and joint angles were not different between control and transition runs for either cycle protocols. Running economy was also not different between control and transition runs for the ow-intensity (62.4 ^ 4.5 vs. 62.1 ^ 4.0 ml/min/kg, p . 0.05) and high-intensity (63.4 ^ 3.5 vs. 63.3 ^ 4.3 ml/min/kg, p . 0.05) cycle protocols. The results of this study demonstrate that both low- and high-intensity cycles do not adversely influence neuromuscular control and running economy in elite international triathletes.

Change in running kinematics after cycling are related to alterations in running economy in triathletes

Emerging evidence suggests that cycling may influence neuromuscular control during subsequent running but the relationship between altered neuromuscular control and run performance in triathletes is not well understood. The aim of this study was to determine if a 45 min high-intensity cycle influences lower limb movement and muscle recruitment during running and whether changes in limb movement or muscle recruitment are associated with changes in running economy (RE) after cycling. RE, muscle activity (surface electromyography) and limb movement (sagittal plane kinematics) were compared between a control run (no preceding cycle) and a run performed after a 45 min high-intensity cycle in 15 moderately trained triathletes. Muscle recruitment and kinematics during running after cycling were altered in 7 of 15 (46%) triathletes. Changes in kinematics at the knee and ankle were significantly associated with the change in VO₂ after cycling (p < 0.05). The change in ankle angle at foot contact alone explained 67.1% of the variance in VO₂. These findings suggest that cycling does influence limb movement and muscle recruitment in some triathletes and that changes in kinematics, especially at the ankle, are closely related to alterations in running economy after cycling.

Altered movement patterns but not muscle recruitment in moderately trained triathletes during running after cycling

Previous studies have shown that cycling can directly influence neuromuscular control during subsequent running in some highly trained triathletes, despite these triathletes' years of practice of the cycle-run transition. The aim of this study was to determine whether cycling has the same direct influence on neuromuscular control during running in moderately trained triathletes. Fifteen moderately trained triathletes participated. Kinematics of the pelvis and lower limbs and recruitment of 11 leg and thigh muscles were compared between a control run (no prior exercise) and a 30 min run that was preceded by a 15 min cycle (transition run). Muscle recruitment was different between control and transition runs in only one of 15 triathletes (<7%). Changes in joint position (mean difference of 3°) were evident in five triathletes, which persisted beyond 5 min of running in one triathlete. Our findings suggest that some moderately trained triathletes have difficulty reproducing their pre-cycling movement patterns for running initially after cycling, but cycling appears to have little influence on running muscle recruitment in moderately trained triathletes.

Neuromuscular adaptations to training, injury and passive interventions: implications for running economy

Performance in endurance sports such as running, cycling and triathlon has long been investigated from a physiological perspective. A strong relationship between running economy and distance running performance is well established in the literature. From this established base, improvements in running economy have traditionally been achieved through endurance training. More recently, research has demonstrated short-term resistance and plyometric training has resulted in enhanced running economy. This improvement in running economy has been hypothesized to be a result of enhanced neuromuscular characteristics such as improved muscle power development and more efficient use of stored elastic energy during running. Changes in indirect measures of neuromuscular control (i.e. stance phase contact times, maximal forward jumps) have been used to support this hypothesis. These results suggest that neuromuscular adaptations in response to training (i.e. neuromuscular learning effects) are an important contributor to enhancements in running economy. However, there is no direct evidence to suggest that these adaptations translate into more efficient muscle recruitment patterns during running. Optimization of training and run performance may be facilitated through direct investigation of muscle recruitment patterns before and after training interventions.

There is emerging evidence that demonstrates neuromuscular adaptations during running and cycling vary with training status. Highly trained runners and cyclists display more refined patterns of muscle recruitment than their novice counterparts. In contrast, interference with motor learning and neuromuscular adaptation may occur as a result of ongoing multidiscipline training (e.g. triathlon). In the sport of triathlon, impairments in running economy are frequently observed after cycling. This impairment is related mainly to physiological stress, but an alteration in lower limb muscle coordination during running after cycling has also been observed. Muscle activity during running after cycling has yet to be fully investigated, and to date, the effect of alterations in muscle coordination on running economy is largely unknown. Stretching, which is another mode of training, may induce acute neuromuscular effects but does not appear to alter running economy.

There are also factors other than training structure that may influence running economy and neuromuscular adaptations. For example, passive interventions such as shoes and in-shoe orthoses, as well as the presence of musculoskeletal injury, may be considered important modulators of neuromuscular control and run performance. Alterations in muscle activity and running economy have been reported with different shoes and in-shoe orthoses; however, these changes appear to be subject-specific and nonsystematic. Musculoskeletal injury has been associated with modifications in lower limb neuromuscular control, which may persist well after an athlete has returned to activity. The influence of changes in neuromuscular control as a result of injury on running economy has yet to be examined thoroughly, and should be considered in future experimental design and training analysis.