Short-Term Hypoxic Exposure and Training Improve Maximal Anaerobic Running Test Performance

Thigh Muscularity and Sprinting Performance of National‐Level Long‐Distance Runners

Long-distance runners require aerobic capacity as well as sprinting ability for superior performance; however, the factors which determine the sprinting ability of long-distance runners remain undetermined. Therefore, the purpose of our study was to examine the association between thigh muscle size and sprinting ability in national-level male long-distance runners. Nineteen male long-distance runners with 5000 m personal-best times of 13:12.63–14:14.87 participated in this study, and transaxial images of their right thighs were collected using magnetic resonance imaging. The cross-sectional areas of the quadriceps femoris, hamstrings, and adductor muscles were calculated from the transaxial images at 30%, 50%, and 70% of the distance from the greater trochanter to the lower edge of the femur; these areas were normalized by body mass. Sprint times for 100 m and 400 m were recorded on an all-weather track. The results revealed positive correlations between the normalized cross-sectional areas of the quadriceps femoris at 50% and 70% of the thigh length and the 100 m (r = 0.666, p = 0.002 and r = 0.531, p = 0.019, respectively) and 400 m sprint times (r = 0.769, p < 0.001 and r = 0.580, p = 0.009, respectively); hence, the larger the quadriceps, the slower the sprint speed. However, no association was found between the normalized cross-sectional areas of the hamstrings or adductor muscles and sprinting performance. Therefore, running motions which activate the quadriceps femoris much more than the hamstrings and adductor muscles should be avoided by national-level long-distance runners.

Neuromuscular activation of the knee and hip extensor muscles during high-intensity interval and moderate-intensity constant cycling

We aimed to test the hypothesis that the magnitude of differences in muscle activation of the knee and hip extensor muscles between high-intensity interval exercise (HIE) and moderate-intensity constant exercise (CE) would be greater for the gluteus maximus than for the quadriceps femoris muscle. Participants were 11 male middle- or long-distance runners. The HIE (4 sets, 4-min induration, performed at 80-85%VO_2peak and followed by a 3-min period of cycling at < 30%VO_2peak) and CE (28-min, performed at or near 60%VO_2peak) were completed on different days, with the total exercise duration and work being identical for both protocols. Surface electromyography (EMG) was recorded from the following muscles: vastus lateralis, vastus medialis, rectus femoris, gluteus maximus, and biceps femoris. The EMG amplitude, normalised over a period of 28 min for both protocols, was significantly greater during HIE than during CE for the gluteus maximus (HIE: 43 ± 4% versus CE: 24 ± 7%) and rectus femoris (HIE: 62 ± 23% versus CE: 47 ± 18%), but had no effect of the exercise protocol on the EMG amplitude of other muscles. These findings indicate that the relative contribution of the gluteus maximus and rectus femoris to the cycling movement can be enhanced using a HIE protocol, in middle- and long-distance runners.