This study aimed to determine the different changes of muscle hardness between the human rectus femoris (RF) and vastus intermedius muscle (VI) after maximal knee extension exercise. Eight healthy men (23.0±2.6 years) performed maximal isometric contraction (IM), concentric contraction (CC), and eccentric contraction (EC) exercises of the knee extensors. Muscle hardness (i.e., strain ratio, SR) and thickness in the proximal, middle, and distal parts of RF and VI were measured by using strain elastography before and after exercises. The rates of change between the values were calculated as values before exercise 100%. For VI, a significant main effect in “part” was found in IM and EC exercises in SR. Results show that SR in the distal part (IM, 89.0±27.2%; EC, 78.2±26.9%) was significantly lower than that in the middle part (IM, 105.5±34.3%; EC, 91.8±30.4%) for each exercise (p<0.05). However, no significant main effect in “part” was found in SR of RF in any exercise. A significant main effect was found in “part” in muscle thickness of RF in the IM exercise. Also, muscle thickness in the distal part (104.5±7.7%) was significantly higher than that in the proximal part (102.5±4.3%) for each exercise (p<0.05). These results suggest that changes of muscle hardness and thickness in the proximal, middle, and distal parts of the human rectus femoris and vastus intermedius muscle after maximal knee extension exercises are different.

BACKGROUND: The Rugby World Cup (RWC) is one of the biggest international mega sports events in the world. This study was conducted to identify and evaluate the volume, nature, and severity of spectator medical care in the stadiums of 12 venues across Japan during RWC 2019. METHOD: This was a retrospective review of medical records from spectator medical rooms of 45 official matches of RWC 2019 between September 20 and November 2, 2019. All patients in the stadium who visited the spectator medical room and were transferred to a hospital were included. The wet bulb globe temperature (WBGT) value at the kick-off time of each match, the number of visits to the spectator medical room, and the number of transfers to a hospital were reviewed and analyzed. The patient presentation rate (PPR) was calculated per 10,000 attendees. Severity categories were defined as mild or severe. Mild cases were considered non-life threatening requiring minimal medical intervention, and severe cases required transport to a hospital. RESULT: The total number of visits to the spectator medical room was 449 with a PPR of 2.63. Most cases (91.5%) were mild in severity. The PPR was significantly higher for the matches held with a WBGT over 25 °C than for the matches under 21 °C (PPR 4.27 vs 2.04, p = 0.04). Thirty-eight cases were transferred to a hospital by ambulance; the PPR was 0.22. The most common reasons for transfer to the hospital were heat illness and fracture/dislocation, at a rate of 15.8% each. The incidence rate of cardiopulmonary arrest per 10,000 attendees was 0.0059 during RWC 2019. CONCLUSION Preparation and provision of appropriate medical service for spectators is a key factor for mass-gathering events. During RWC 2019, the majority (91.5%) of patients who sought medical attention did so for minor complaints, which were easily assessed and managed. On the other hand, a higher WBGT situation contributes significantly to an increased PPR (< 21 versus > 25, 2.04 versus 4.27, p = 0.04). Careful medical preparation, management, and development of public education programs for higher WBGT situations will be required in the future for similar international mega sports events.
Adolescent ; Adult ; Aged ; Aged, 80 and over ; Ambulatory Care/statistics & numerical data* ; Anniversaries and Special Events ; Child ; Child, Preschool ; Emergency Service, Hospital/statistics & numerical data* ; Female ; Football ; Hospitalization/statistics & numerical data* ; Humans ; Infant ; Infant, Newborn ; Japan ; Male ; Mass Behavior ; Middle Aged ; Retrospective Studies ; Young Adult