We aimed to examine the relationship between marathon time and running distance during 8 months before a race for runners who live in cold, snowy regions and those who do not. A questionnaire was conducted for male runners who participated in the 2018 Hokkaido Marathon held at the end of August. The subjects were divided into runners from Hokkaido (Hokkaido runners), which is a cold and snowy region, and runners from other regions (non-Hokkaido runners). In addition, Hokkaido and non-Hokkaido runners were divided into two groups, high-volume and low-volume runners, based on their average running distance over an 8-month period. Regardless of high-volume or low-volume, Hokkaido runners’ monthly running distances significantly increased from March compared to January, but non-Hokkaido runners showed no change in their monthly running distances. For non-Hokkaido runners, a significant correlation was found between cumulative monthly running distance and marathon time starting from 8 months prior to the marathon. On the other hand, among Hokkaido runners, no correlation was found between cumulative monthly running distance and marathon time for low-volume runners from January to April, or for high-volume runners from January to February or January to March. These results suggest that marathon times for runners from cold, snowy regions are more closely linked to seasonal changes in running distance than for other runners.

Knee injuries in rugby union have higher incidence and severity than other injury types. However, the underlying mechanisms and trauma remain unclear. This study aimed to identify knee injury trends and clarify the associated mechanisms in male university rugby players using longitudinal injury surveillance and video analysis. An observational study with longitudinal injury surveillance included 198 university male rugby players who played at least one season over a six-season period (2017–2022). The mean incidence, severity, and burden of injuries were calculated by position and injury type. Video data of knee injuries in matches were analyzed by three analysts, who independently assessed variables, including mechanism/play, movement/posture, and external factors. Injury mechanisms were classified as direct, indirect, and non-contact. The incidence of knee injuries was 8.3/1000 h, with 29 videos analyzed. Indirect contact injury was the most frequent, with an incidence of 3.7/1000 h and a burden of 380 days/1000 h. A significant association was found between injury severity and movement direction, with being tackled from downwards and sideways directions showing a significant difference compared to other directions (Cramer’s V = 0.44). Most knee injuries were caused by being tackled, a heel strike, and an upright body position. Indirect injuries, the most frequent knee injury mechanism, imposed the highest burden. Movement direction may further affect injury severity. Despite their lower incidences, these injuries cause greater burden and severity than those observed in professional rugby, emphasizing the need for specialized prevention programs.

American football (AF) has a high incidence of sports-related concussions (SRC), raising concerns about the long-term effects on neuromuscular function. This study aimed to compare the cortical silent period (cSP) and the strength of the cervical muscles to investigate neuromuscular function in patients with SRC. All 38 participants were males, including 12 AF players with a history of SRC, 9 AF players without a history of SRC, and 17 normal healthy males with no experience in contact sports. Cervical muscle strength was measured with a hand-held dynamometer. cSP was measured using transcranial magnetic stimulation. Electromyography was obtained from the upper trapezius muscle. AF players demonstrated stronger cervical muscle strength than the control group. No significant differences were observed in corticospinal excitability among the groups. AF players with a history of SRC demonstrated a significantly longer cSP than the control group (80.5 ± 27.8 ms vs. 113.1 ± 35.1 ms) (F (2, 32) = 3.66, p < .05). These results suggest that cortical inhibition of the cervical muscle is enhanced in AF players with a history of SRC. This could lead to neuromuscular dysfunction of the cervical muscles and should be considered an important factor in preventing recurrent SRC.

This study aimed to determine the effect of running step frequency (SF) on oxygen consumption during running on spot (ROS) exercises and low-speed running in adult male and female participants. Twenty Japanese participants (22 ± 1.2 years) were included. ROS exercises and running speeds of 4 km h^-1 and 5 km h^-1 were measured at SFs of 140, 160, 180 and 200 steps min^-1. Oxygen consumption, heart rate (HR), and rate of perceived exertion (RPE) were measured during exercise, and oxygen consumption were expressed as metabolic equivalents (METs). In the participants, ROS and 4 km h^-1 running showed no significant difference in SFs (140 steps min^-1 and 160 steps min^-1, respectively) and had significantly higher SFs of 200 steps min^-1 than the other SFs. Moreover, 5 km h^-1 running showed no significant difference between SFs of 140 steps min^-1, 160 steps min^-1 and 180 steps min^-1, and was significantly higher at an SF of 200 steps min^-1 than other SFs. Individual differences in METs at an SF of 180 steps min^-1 were similar at running speeds of 4 km h^-1 and 5 km h^-1. No difference was noted in oxygen consumption between SF of 140 steps min^-1 and 160 steps min^-1 during ROS exercise and 4 km h^-1 and 5 km h^-1 running. Oxygen consumption tended to increase depending on SF above 160 steps min^-1 during ROS, 4 km h^-1, and 5 km h^-1 running exercises. These results suggest that SF should be considered for low-speed running instruction.