Functional relationship between the anatomical structures of the calf and athletic ability.

Calf muscle plays an important function in driving the movement of stepping on the ground and moving forward when walking or running. The Achilles tendon has been reported to be closely related to the elasticity of tendons to absorb shock and rebound and convert energy into propulsion. We wanted to determine the effect and correlation of the anatomical structure of the calf region on function. Measurements of anatomical structures were conducted with 51 volunteers using ultrasonography, and exercise capacity tests were conducted to measure anaerobic power, elasticity, and flexibility. The mean power and length of the calf (LoC), muscle thickness (MT), and fascicle angle (FA) of the medial head of gastrocnemius (p < 0.001) showed the strongest positive correlation among the variables of anatomical structures. MT of the Gastrocnemius and LoC Gastrocnemius were also correlated with peak power. In the anatomical structure variables, the FA of the lateral head of gastrocnemius, length and width of the Achilles tendon, and part of the athletic ability, the standing long jump test and sitting trunk flexion test, were not significantly correlated. Based on these results, it can be concluded that the height and degree of development of the calf muscles are structures that affect the exercise of anaerobic power. Hence, it can be used as a predictor of athletic ability. Furthermore, the trainer can predict athletic ability according to the characteristics of the event by first understanding the athlete's physical condition.

Correlation between muscle architecture and anaerobic power in athletes involved in different sports.

Athletes cultivate highly developed muscles based on their sport category, creating a body shape that matches the characteristics of that sports category. We tested the significance of the correlation between muscle development characteristics and anaerobic power in athletes to build a database for each category. Fifty-eight college athletes participated in this study. To assess muscle characteristics, muscle thickness (MT) and fascicle angle (FA) were measured by ultrasonography (US) in lower limb. Furthermore, anaerobic power was measured with the Wingate test. Analysis of the correlation between muscle structure and anaerobic power revealed significant differences between the sports categories, except for the MT of the medial head of gastrocnemius (Gm), lateral head of gastrocnemius, and FA of Gm. A significant difference was observed for all parameters, except for the arrival time to peak power in the anaerobic power items; in particular, a high degree of correlation in mean power/kg and peak power/kg was observed. A similar tendency was observed in the correlation between muscle structure and anaerobic power in most sports categories, but certain muscle characteristic factors were prominent in each sport. Based on these, it is possible to contribute to predicting and promoting athletic performance.

Effects of skim milk powder intake and treadmill training exercise on renal, bone and metabolic parameters in aged obese rats.

PURPOSE: we aim to examine whether adding exercise has impact on obesity prevention and bone metabolism in senior rats, to which dietary obesity was induced through skim milk intake. METHODS: We used 47, 14-week old Sprague -Dawley (SD) female rats (CLEA Japan, Inc.). The Rats were separated into four random groups: 1) a Non-Ex group with a normal diet (n = 12), 2) an Ex group with a normal diet (n = 12), 3) a Non-Ex group with a skim milk diet (n = 11), and 4) an Ex group with a skim milk diet (n = 12). As the exercise for each Ex group, rats ran on a treadmill starting at 27-week old (TREADMILL CONTROL LE8710 and TREADMILL CONTROL LE8700, Harvard Bioscience). Training protocol stipulated a frequency of five times a week for 12 weeks. RESULTS: The leptin concentration differed with dietary content: compared to the Ex group with a skim milk diet, Non-Ex and Ex groups with a normal diet showed significantly higher values (p < 0.05). The Ex group had significantly lower values in both the normal diet and skim milk diet groups with or without exercise (p < 0.05). Compared to the Non-Ex group with a normal diet, BS/BV (mm(2)/mm(3)), BV/TV (%), Tb.Th (µm), TBPf (/mm) and Tb.N (/mm) had significantly lower in the Ex group, the Ex and Non-Ex groups with a whey protein diet, and the Ex group with a skim milk protein diet (p < 0.05). CONCLUSION: These findings suggest that senior female rats fed SMP would have higher bone structural and strength parameters than rats fed a normal diet.

Dose-dependent effect of capsaicin on endurance capacity in rats.

The present study was designed to determine the effects of various levels of capsaicin (CAP) on endurance capacity in forty-nine male Sprague-Dawley rats, aged 4 weeks, which were assigned to four groups. Rats were given orally either control (0) or 6, 10 or 15 mg CAP/kg body weight 2 h before exercise by stomach intubations using a round-ended needle. The rats in each group were divided into two subgroups for resting or swimming exercise. Swimming exercise was performed with a weight corresponding to 3 % body weight attached to the tail, and endurance capacity was evaluated by swimming time to exhaustion. The highest dose (15 mg/kg) of CAP significantly (P<0.05) increased endurance performance time and caused plasma non-esterified fatty acid to rise significantly by about 1.4-fold compared with that of non-CAP treated rats at exhaustion (P<0.05). The highest dose of CAP had no effect on liver and gastrocnemius muscle glycogen (white and red) in resting rats, but significantly increased glycogen contents of both muscles at exhaustion (P<0.05). At rest, plasma noradrenalin levels of the rats receiving the highest dose were greater than that of non-CAP-treated rats and remained greater until exhaustion. The effects of CAP on endurance capacity have received little attention and have conveyed conflicting impressions. Kim et al. (1997) failed to show the maximal effect of 10 mg/kg doses of CAP on swimming endurance time in mice. The influences of various doses of CAP on endurance capacity were still unclear. Matsuo et al. (1996) reported that the intake of CAP have little sparing effect on glycogen in the liver and soleus muscles at rest and during exercise in rats previously fed a CAP-containing diet ad libitum for 1 week. Our present results suggest more than the highest dose of CAP (15 mg/kg) can cause the increase of endurance capacity, which might be induced through the sparing of muscle glycogen and the rise of non-esterfied fatty acids following the increase of circulating catecholamine.

Capsaicin increases endurance capacity and spares tissue glycogen through lipolytic function in swimming rats.

The influences of various doses of capsaicin on endurance capacity remain to be clarified. The purpose of this study was to determine whether or not capsaicin delays stored tissue glycogen depletion. Rats were orally given either a vehicle or a dose of capsaicin, 6, 10, or 15 mg/kg of body weight, 2 h before exercise. The rats in each group were divided into three subgroups for resting and swimming exercise (30 min, exhaustion). Swimming exercises were performed with a weight corresponding to 3% body weight attached to the tail, and the endurance capacity was evaluated by the swimming time until exhaustion. The 15 mg/kg dose of capsaicin significantly (p < 0.05) enhanced the endurance performance time and plasma concentration of epinephrine, norepinephrine, free fatty acid and glucose rose to significantly higher levels within 30 min; swimming exercise compared to rest (p < 0.05). At the 15 mg/kg capsaicin dosage. the plasma insulin level decreased to significantly lower levels in group subjected to 30-min swimming as compared to the resting group (p < 0.05), while plasma glucagon rose to a significantly higher level (p < 0.05). Liver and gastrocnemius muscle glycogen in the group subjected to 30-min swimming was maintained at significantly higher concentrations in the rats fed 15 mg/kg of capsaicin as compared to the vehicle counterparts (p < 0.05). These results suggest that the improvement in swimming endurance with the high capsaicin dosage is caused by an increase in fatty acid utilization as the energy source, resulting in the sparing of glycogen.

Effects of habitual chitosan intake on bone mass, bone-related metabolic markers and duodenum CaBP D9K mRNA in ovariectomized SHRSP rats.

We have demonstrated that the habitual intake of chitosan can decrease bone mass in ovariectomized (OVX) SHRSP rats fed a low-Ca diet (0.1%). In the present study, we examined both the etiology of bone loss induced by dietary chitosan and the preventive effect of vitamin C supplementation. Rats were OVX and maintained on one of the following diets for 6 wk: 10% cellulose (CE). 10% chitosan (CH) or 10% chitosan with sodium ascorbate (CHVC). CH caused a significant reduction in bone mineral density (BMD) and stiffness in femurs and the fourth lumbar vertebrae (L4). There was no significant difference in intestinal Ca absorption between CH and CE, whereas CH intake significantly reduced intestinal P absorption. The bone loss in CH rats was accompanied with an increase in urinary Ca excretion and a decrease in serum Ca as well as a significant increment In serum PTH and 1,25(OH)2D3. The vitamin D receptor and calcium binding protein D9K mRNAs were also significantly increased in the duodenum of CH rats. Vitamin C supplementation to CH caused an increase in the Ca and P contents of femurs as well as BMD of the L4, with a decrease in urinary Ca excretion. These results indicate that dietary chitosan with low Ca intake possibly induces the loss of bone mass by enhancing urinary Ca excretion rather than by inhibiting Ca absorption, and that vitamin C supplementation could prevent bone loss caused by chitosan through the increment of retained Ca followed by suppression of urinary Ca excretion.