Engagement in different sport disciplines during university years and risk of locomotive syndrome in older age: J-Fit

BACKGROUND@#Among former Olympic-level athletes, engagement in different sport disciplines has been associated with mortality risk in subsequent years. However, limited evidence is available on whether engagement in different sport disciplines at a young age is associated with locomotive syndrome (LS) risk later in life. This study examined the relationship between engagement in different sport disciplines during university years and LS risk in older age among former university athletes.@*METHODS@#Participants were 274 middle-aged and 294 older men alumni who graduated from a school of physical education in Japan. LS risk was defined as answering "yes" to any of the Loco-check questions. Data on university sports club membership were collected using questionnaires. University clubs were classified into three groups of cardiovascular intensity (low, moderate, high), following the classification system of sport disciplines by the American College of Cardiology. This classification considers the static and dynamic components of an activity, which correspond to the estimated percent of maximal voluntary contraction reached and maximal oxygen uptake achieved, respectively. University clubs were grouped based on the risk of bodily collision (no, yes) and extent of physical contact (low, moderate, high). Relationships between engagement in different sport disciplines and LS risk were analyzed using Cox proportional hazards models, and adjusted for age, height, weight, joint disease, habitual exercise, and smoking and drinking status.@*RESULTS@#Adjusted hazard ratios and 95% confidence intervals associated with the low, moderate, and high cardiovascular intensity sports were 1.00 (reference), 0.48 (0.22-1.06, P = 0.070), and 0.44 (0.20-0.97, P = 0.042) in older men, respectively; however, there was no significant association between these parameters among middle-aged men. Engagement in sports associated with physical contact and collision did not affect LS risk in either group.@*CONCLUSIONS@#Engagement in sports associated with high cardiovascular intensity during university years may reduce the risk of LS in later life. Encouraging young people to participate in such activities might help reduce LS prevalence among older populations.

EFFECTS OF COMBINATION OF HEAT STRESS AND ASTAXANTHIN SUPPLEMENTATION ON DISUSE MUSCLE ATROPHY / 体力科学

The purpose of this study was to examine the effects of combination of a heat stress and astaxanthin supplementation, known as a potent anti-oxidative nutrient, on muscle protein degradation and disuse muscle atrophy. Fifty-two male Wistar rats (261.7±1.17 g) were divided into five groups: control (Cont, n=10), suspension (Sus, n=11), heat stress and suspension (Heat, n=10), astaxanthin and suspension (Ax, n=10), and heat stress, astaxanthin and suspension (H+A, n=11). There were no significant differences in Cu,Zn-SOD, cathepsin L and caspase-3 levels among the Heat, Ax and H+A groups in the soleus and plantaris muscles. Although levels of calpain 2 and ubiquitinated protein in the myofibrillar fraction in the soleus muscle were not significantly different among the Heat, Ax and H+A groups, levels in the H+A group were significantly (p<0.05) lower than Sus. Concerning atrophied plantaris muscles, the H+A group significantly (p<0.05) suppressed the expression of calpain 1 in the myofibrillar fraction, but there were no marked changes of proteolytic indexes. These data indicate that the combination of the heat stress and astaxanthin supplementation could be effective in inhibiting muscle protein degradation in disuse atrophy of the soleus.

EFFECT OF HEAT STRESS ON DESMIN EXPRESSION IN ATROPHIED SOLEUS MUSCLE / 体力科学

In the present study, we investigated the effect of heat stress on disuse atrophy from changes in the muscle protein levels of desmin and calpain. Wistar strain female rats (6-8 months old) were randomly assigned to two experimental groups: control (C) and heat stress (H). One hindlimb of all animals was immobilized in plantar flexion with plaster. Before immobilization, animals in H group were placed in a heat chamber (42°C for 60 min). Following 6 days of immobilization, the soleus muscles were removed and analyzed. Although immobilization resulted in significant muscle atrophy in all experimental animals, the soleus weight-to-body weight ratio in immobilized limbs of H group was significantly higher compared to that of C group. Expression of desmin and HSP72 in the atrophied soleus muscle from C group was significantly lower compared with the contralateral muscle; but this was not the case in H group. Further, in C group, the ratio of autolyzed calpains I increased significantly in the atrophied muscle compared to the contralateral muscle. These results show that the effect of heat stress on disuse skeletal muscle atrophy is attributed to the decreasing degradation of desmin by suppressing the activation of calpain.

EFFECT OF LONG-TERM DIETARY ASTAXANTHIN INTAKE ON SARCOPENIA / 体力科学

Oxidative stress is thought to be a significant contributing factor of age-related sarcopenia. We tested the hypothesis that long-term dietary antioxidant (astaxanthin) intake attenuates sarcopenia. Wistar strain male rats, aged 45 weeks old, were given either control (Cont) or astaxanthin feed (0.004%, Ax) for 1 year. The soleus muscle weight and muscle weight-to-body weight ratios in Ax group were significantly higher than in Cont group, but tibialis anterior muscle mass was similar between the two dietary groups. The level of ubiquitinated proteins was significantly lower in the soleus muscles of Ax group, but not in tibialis anterior muscles when compared with Cont group. Tibialis anterior levels of cathepsin L, especially, and caspase-3 tended to be lower in Ax group than in Cont group. Cathepsin L levels were significantly lower. Whereas no differences between Cont and Ax were observed in soleus levels. There were no significant differences in Ax supplementation on calpain 1 and 2, UBC3B, Cu/Zn SOD and nitrotyrosine levels in either soleus or tibialis anterior muscles. Our data suggest that long-term dietary astaxanthin intake attenuates age-related muscle atrophy, due in part, to reduction in ubiquitination of myofibrillar protein in slow soleus muscles, but not in fast tibialis anterior muscles.

QUANTIFYING TIME SPENT IN MODERATE TO VIGOROUS INTENSITY PHYSICAL ACTIVITY VIA STEPPING RATE / 体力科学

The purpose of the present investigation was to examine the usefulness of the stepping rate for assessing the time spent in moderate to vigorous intensity physical activity (MVPA). In the present investigation, 11 young men wore two pedometers (LIFECORDER EX ; KZ, Walking Style ; WS) during controlled walking and jogging, as well as during free-living conditions for 3 days. In addition to the number of steps, the KZ determined the time spent in physical activity based on the intensity of the physical activity (light intensity physical activity (LPA); below 3 METs, and MVPA ; above 3 METs), and the stepping rate (≧60, ≧80, or ≧100 steps·min^-1). In contrast, the WS was defined as the physical activity for a stepping rate of 60 steps·min^-1 or more, continuously for longer than 10 min as the time spent in physical activity. Regarding the results, under continuous walking/jogging, the KZ-assessed LPA and MVPA well reflected the intensity of the physical activity. On the other hand, the WS accumulated the time spent in physical activity for longer than 90% of the actual exercise duration, regardless of the walking speed. Furthermore, the stepping rate corresponding to 3 METs was 102 steps·min^-1. Under free-living conditions, however, the KZ-detected MVPA differed significantly in comparison to the time of the physical activity as determined by the other algorithms, except for the time spent in a stepping rate of 80 or higher steps·min^-1. In conclusion, these results indicate that 100 steps·min^-1 is a useful stepping rate for the assessment of MVPA. However, under free living conditions, the stepping rate should be determined at a higher frequency than a one minute interval length in order to improve the accuracy of the MVPA assessment.

RELATIONSHIP BETWEEN OPEN-WATER SWIMMING PERFORMANCE AND AEROBIC CAPACITY / 体力科学

The purpose of the present investigation was to examine the relationship between the open water swimming (OW) performance and the swimming speed at 2, 3, and 4 mmol/l of blood lactate concentration (SSLA2, SSLA3, and SSLA4) or the critical swimming speed (CSS). Six male collegiate swimmers performed the 10 kilometers of OW, as well as the multi-stage graded swimming test, in order to determine the SSLA2, SSLA3, SSLA4. Furthermore, the CSS was calculated based on the personal best records for 50 to 1500 meters of free-style indoor swimming. As a result, the SSLA2, SSLA3, SSLA4, and CSS corresponded to 102±6%, 106±6%, 110±7%, and 106±5% of the average swimming speed of the OW, respectively. Thereafter, the SSLA2 did not differ significantly in comparison to the average swimming speed of the OW, whereas the SSLA3, SSLA4, and CSS differed significantly with the average swimming speed of the OW (p＜0.05). Furthermore, the average swimming speed during the OW significantly correlated with the SSLA2, SSLA3, SSLA4, and CSS, respectively (p＜0.05). These results suggest that the OW performance significantly correlated with the swimming speed at 2 to 3 mmol/l of the blood lactate concentrations and CSS. Furthermore, regarding these parameters, the SSLA2 may accurately reflect the average swimming speed of OW.

CHANGES IN HEAT SHOCK PROTEIN INDUCTION IN RAT SKELETAL MUSCLES FOLLOWING ACUTE TREADMILL TRAINING AT DIFFERENT SPEEDS / 体力科学

It has been demonstrated that exercise induces heat shock proteins (HSPs) . However, no study has investigated changes in HSPs following endurance training at different speeds. Therefore, this study was designed to investigate the effect of treadmill training at different running speeds on induction HSPs. One group of male Wistar rats was assigned as a sedentary control, three groups were assigned for exercise training (10 m/min, 20 m/min and 30 m/min) and another three groups for one acute bout of exercise (10 m/min, 20 m/min and 30 m/min) . Each training group ran at each speed for 30 min/day, 5 days a week for 8 weeks. The acute exercise group performed the exercise only once. Forty-eight hours after the last exercise session was completed, the rats were sacrificed and the plantaris (PLA) and soleus (SOL) muscles were dissected. In the acute exercise group, the content of HSP72 in both the PLA and SQL increased (p<0.05) at all speeds, and the content of HSP60 increased significantly (p<0.05) at all speeds for the PLA, but not for the SOL. On the other hand, in the endurance group, the content of HSP72 and HSP60 in both muscles increased in 30 m/min groups. These results indicate that an increase in HSP72 and HSP60 by endurance training is induced by high intensity training in both muscles. This was not found to be the case with the acute exercise groups.

The effect of endurance training on the pancreatic enzyme activity in aged rats / 体力科学

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<SUP>-1</SUP>, OT 22 m⋅min<SUP>-1</SUP>), 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.