The purpose of the present study was to investigate the effect of endurance running training on pancreatic enzyme activity in aged rats. Young (Y ; age, 12 weeks) and old (O ; age, 100 weeks) female Fischer 344 rats were divided into control (YC ; n = 6, OC ; n = 4) and trained (YT ; n = 6, OT ; n=7) groups respectively. Rats in the YC and OC groups were kept sedentary. Rats in the YT and OT groups ran up a 15% gradient treadmill for 60 min a day (final speed, YT : 32 m ⋅min-1, OT 22 m⋅min-1), 5 days a week. After 10 weeks, the pancreas was excised and weighed. Protein content, amylase and lipase activities in pancreatic tissue were measured. Pancreatic wet weight, protein content, and enzymes (amylase and lipase) activity in the OC group were significantly lower than in the YC group. However, these parameters in the OT group were significantly higher than in the OC group. These results suggest that endurance training may restore the age-related decrease of pancreatic enzyme synthesis and storage.
A study was conducted to evaluate and compare neck muscle strength between two levels of college American football players with the aim of preventing neck injuries. The subjects were American football players at N University (n=52) belonging to the first level league and American football players at G University (n=14) belonging to the third level league. The findings were as follows. 1. The neck muscle strength of freshman players at N University tended to be lower than that of senior players. 2. It was shown that the neck muscle strength/body weight of experienced American football players was 10-30% higher than that of inexperienced players. 3. There was a significant difference in neck muscle strength/body weight between N University and G University in 1997. However, there was no significant difference between them in 1998, because neck muscle strength/body weight of G University players increased by 13-30% after neck muscle training for about nine months. It was suggested that coaching staff must evaluate the neck muscle strength of each player, especially in freshmen who have had no experience of American football, in order to prevent neck injuries because mismatch of performance level may cause catastrophic neck injury.
This study tried to establish both critical and desirable levels of health-related physical fitness (HRPF) including muscle strength (relative grip strength), flexibility and estimated VO2max. Subjects were 3102 males aged 20 to 59 years. Four batteries of health index score (HIS-A-D) were made based on health examinations and lifestyle habits. Subjects who had 0 to 1 points were defined as healthy individuals, and subjects who had more than 3 or 4 points were defined as unhealthy. Receiver-operating characteristic (ROC) curves were drawn by HRPF test in each battery of HIS. The HIS-B was selected as the most valid battery of HIS. Sensitivity, specificity and the Youden index were calculated using cut-off values which were mean values of each HRPF test measurement in each group who had 0, 1, 2, 3 and>4 points in HIS-B. The critical levels were defined the highest specificity and/or Youden index in each HRPF test. There were seen in groups having > 4 points. The desirable levels were defined as the HRPF test levels in healthy individuals who had 0 to 1 points in HIS-B. The critical and desirable levels of VO2max were 41.8 and 50.2 at 20y, 40.9 and 46.2 at 30y, 40.0 and 46.2 at 40y, and 37.8 and 45.5 ml/kg/min at 50y, respectively. The levels of other HRPF test were also calculated in the present study. Exercise guidance after health check-ups should be done to attain desirable levels rather than to just maintain critical levels of HRPF.
This study aims to examine the effects of kinesio taping (KT) on explosive muscle and sustained maximal muscle exertions of lower limbs in pre- and post-strenuous exercises (SE) up to exhaustion. Twenty healthy college males (mean age 20.4 ± 1.08 yr) participated in the experiment for both the conditions of strapping KT (KT group) and no strapping KT (control group) . They all took pre- and post-SE isokinetic tests (IK test) . The KT was strapped around muscle groups related to flexion and extension motions of a knee joint before the experiment. The effects of KT were confirmed on the exertion of the explosive muscle strength in flexion motion of post-SE, and the sustained muscle strength in pre- and post-SEs. It was inferred that the effects of KT relate to the fatigue state of muscle groups related to motion and motion types, and interpretation of these effects differs by the load intensity and the variables used for evaluation.
The gastrocnemius muscles are composed predominantly of type II B and II A fibers while the soleus muscle is composed of type I fibers. However, the relationships between the calcaneal bone stiffness and the triceps surae muscles consisting of the different types of skeletal muscle fibers are unknown. The purpose of this study was to investigate the relationships between the calcaneal bone stiffness and the gastrocnemius or soleus muscle thickness in 73 postmenopausal women. We measured the speed of sound (SOS) and the broad band ultrasound attenuation (BUA), using a ultrasonic measurement of the calcaneal and the gastrocnemius or soleus muscle thickness used to measure the B-mode ultrasound anatomy. There was a significant differences in age between the high-and low-SOS groups. In the high-BUA group, the body mass index, the lower leg girth and the triceps surae muscle thickness were significantly higher than those in the low-BUA group. This data indicated that SOS is related to ageing and BUA is related to the body mass or the muscle thickness. The other side, stiffness and SOS were significantly correlated with the gastrocnemius muscle thickness, but not with the soleus muscle mass. Therefore, this study suggests that the calcaneal bone stiffness is closely related to the muscle thickness, which may be related especialy to the fast twitch muscle.
In a recent study, endurance athletes, i.e. cyclists and long-distance runners, were found to have larger arterial conductance vessels than untrained controls. The aim of the present study was to determine the blood flow profiles of dilated vessels in these endurance-trained athletes. Twelve endurance-trained athletes (ET group) and twelve untrained control subjects (UC group) volunteered for the study. The cross-sectional area (CSA), peak and mean blood velocity in the ascending aorta (pV and mV), blood pressure (BP), and heart rate (HR) were measured in the semi-supine position on a cycle ergometer fitted with a backrest, at rest and during exercise at 40%, 60%, and 80%Vo2max. Furthermore, stroke volume (SV), cardiac output (CO), total peripheral resistance, and double product were calculated. The SV and CO of the ET group were significantly larger than those of the UC group during exercise. The CSA of the ascending aorta in the ET group was significantly larger than that in the UC group at rest and during exercise. There were no differences in the mV and mean BP between the two groups. Upon comparison at the same SV, pV, mV, the total peripheral resistance, and double product of the ET group were lower than those of the UC group. These results suggest that the dilation of the arterial conductance vessels with endurance training contri-butes to an increase in blood flow to the exercising muscles without a rise in mechanical stress (shear stress and pressure) to the aortic wall. In other words, the arterial conductance vessels adapt morphologically to maintain an adequate degree of the mechanical stress on the aortic wall.