The Muller F element (4.2 Mb, ~80 protein-coding genes) is an unusual autosome of Drosophila melanogaster; it is mostly heterochromatic with a low recombination rate. To investigate how these properties impact the evolution of repeats and genes, we manually improved the sequence and annotated the genes on the D. erecta, D. mojavensis, and D. grimshawi F elements and euchromatic domains from the Muller D element. We find that F elements have greater transposon density (25–50%) than euchromatic reference regions (3–11%). Among the F elements, D. grimshawi has the lowest transposon density (particularly DINE-1: 2% vs. 11–27%). F element genes have larger coding spans, more coding exons, larger introns, and lower codon bias. Comparison of the Effective Number of Codons with the Codon Adaptation Index shows that, in contrast to the other species, codon bias in D. grimshawi F element genes can be attributed primarily to selection instead of mutational biases, suggesting that density and types of transposons affect the degree of local heterochromatin formation. F element genes have lower estimated DNA melting temperatures than D element genes, potentially facilitating transcription through heterochromatin. Most F element genes (~90%) have remained on that element, but the F element has smaller syntenic blocks than genome averages (3.4–3.6 vs. 8.4–8.8 genes per block), indicating greater rates of inversion despite lower rates of recombination. Overall, the F element has maintained characteristics that are distinct from other autosomes in the Drosophila lineage, illuminating the constraints imposed by a heterochromatic milieu.

The aim of this study was to analyse the important kinematic variables in elite men's and women's 20 km race walking. Thirty men and 30 women were analysed from video data recorded during the World Race Walking Cup. Video data were also recorded at four points during the European Cup Race Walking and 12 men and 12 women analysed from these data. Two camcorders operating at 50 Hz recorded at each race for 3D analysis. The two main performance determinants of speed were step length and cadence. Men were faster than women because of their greater step lengths but there was no difference in cadence. A reduction in step length was the initial cause of slowing down with later decreases in speed caused by reductions in cadence. Shorter contact times were important in optimising both step length and cadence, and faster athletes tended to have longer flight times than slower athletes. It was less clear which other kinematic variables were critical for successful walking, particularly with regard to joint angles. Different associations were found for some key variables in men and women, suggesting that their techniques may differ due to differences in height and mass.

Race walking is an endurance event which also requires great technical ability, particularly with respect to its two distinguishing rules. The 50 km race walk is the longest event in the athletics programme at the Olympic Games. The aims of this observational study were to identify the important kinematic variables in elite men's 50 km race walking, and to measure variation in those variables at different distances. Thirty men were analysed from video data recorded during a World Race Walking Cup competition. Video data were also recorded at four distances during the European Cup Race Walking and twelve men analysed from these data.Two camcorders (50 Hz) recorded at each race for 3D analysis. The results of this study showed that walking speed was associated with both step length (r = .54, P = .002) and cadence (r = .58, P = .001). While placing the foot further ahead of the body at heel strike was associated with greater step lengths (r = .45, P = .013), it was also negatively associated with cadence (r = -.62, P < .001). In the World Cup, knee angles ranged between 175 and 186° at initial contact and between 180 and 195° at midstance. During the European Cup, walking speed decreased significantly (F = 9.35, P = .002), mostly due to a decrease in step length between 38.5 and 48.5 km (t = 8.59, P = .014). From this study, it would appear that the key areas a 50 km race walker must develop and coordinate are step length and cadence, although it is also important to ensure legal walking technique is maintained with the onset of fatigue.

In this study, we observed the variations on physiological and perceptual variables during a self-paced 10,000-m race walking (RW) event with the aim to trace a preliminary performance profile of the distance. In 14 male athletes, the heart rate (HR) was monitored continuously throughout the event. The rating of perceived exertion (RPE) was collected using the Borg's 6-20 RPE scale placed at each 1,000 m of an outdoor tartan track. Pacing data were retrieved from the official race results and presented as percent change compared with the first split time. The athletes spent 95.4% at 90-100% of the HRpeak, whereas the other work (4.6%) was negligible. During the race, a shift toward higher HR values was observed because % HRpeak increased by 3.6% in the last vs. the first 1,000-m sector (p = 0.002, effect size [ES] = 1.55 ± 0.68, large). The mean RPE reported by the athletes in the last 1,000 m was significantly higher than in the first 5 sectors (p < 0.02, ES = 1.93-2.96, large to very large). The mean percent change increased between the first 6 sectors and the last 1,000-m sector (p < 0.01, ES = 1.02-2.1, moderate to very large). The analysis of walking velocity at each 1,000-m sector suggested the adoption of a negative pacing. In conclusion, the RPE may be a valid marker of exercise intensity even in real settings. Match physiological and perceptual data with work rate are required to understand race-related regulatory processes. Pacing should be considered as a conscious behavior decided by the athletes based on the internal feedback during the race.

No abstract

Purpose: To compare the effects of natural altitude training (NAT) and simulated (SIM) live high:train low altitude training on road-race walking performance (min), as well as treadmill threshold walking speed (km·h−1) at 4 mmol·L−1 and maximal oxygen consumption, at 1380 m. Methods: Twenty-two elite-level male (n = 15) and female (n = 7) race walkers completed 14 d of NAT at 1380 m (n = 7), SIM live high:train low at 3000:600 m (n = 7), or control conditions (600-m altitude; CON, n = 8). All preintervention and postintervention testing procedures were conducted at 1380 m and consisted of an incremental treadmill test, completed prior to a 5 × 2-km road-race walking performance test. Differences between groups were analyzed via mixed-model analysis of variance and magnitude-based inferences, with a substantial change detected with >75% likelihood of exceeding the smallest worthwhile change. Results: The improvement in total performance time for the 5 × 2-km test in NAT was not substantially different from SIM but was substantially greater (85% likely) than CON. The improvement in percentage decrement in the 5 × 2-km performance test in NAT was greater than in both SIM (93% likely) and CON (93% likely). The increase in maximal oxygen consumption was substantially greater (91% likely) in NAT than in SIM. Improvement in threshold walking speed was substantially greater than CON for both SIM (91% likely) and NAT (90% likely). Conclusions: Both NAT and SIM may allow athletes to achieve reasonable acclimation prior to competition at low altitude.