A study on the physical fitness of elderly weekly hill walkers / 体力科学

The purpose of this study was to research the physical fitness of elderly weekly hill walkers by comparison with general average values for Japanese. The participants total 77 members (28 males and 49 females) of a mountaineering party who did a hill walking once a week for at least 1 year. The test of physical fitness consisted of muscle strength (knee extension strength, back strength, grip strength and sit ups), agility (reaction time), body flexion (long sitting forward reach), balance (one-leg balancing with eyes open) and ability of daily physical actions (10-times-reapeated sit-to-stand test and 5m maximal walking test). The general average values were taken from several previous studies considered to be highly appropriate as the general average. For statistical analysis, unpaired t-test using the number of subjects, means and standard deviations of previous studies was performed. As a result, the 4 muscle strength tests were significantly higher than the general average value (P<0.001). In addition, the agility test and 2 abilities of daily physical action’s tests were significantly faster than the general average value (P<0.001). Moreover, there was no relationship between the value of knee extension and ages, but it existed in between annual climbing number of days (male: r=0.40, P<0.05, female: r=0.35, P<0.05). In conclusion, it appears that elderly people who climb the low mountain weekly have the higher physical fitness than general average values, and it can be inferred that weekly hill walking in low mountains can potentially keep higher knee extension regardless of age.

Differences in cardiorespiratory and metabolic responses between body mass-based squat and lunge exercises with relation to muscular activity with relation to muscular activity level / 体力科学

<p>This study aimed to clarify the differences in cardiorespiratory and metabolic responses to body mass-based front lunge and squat exercises with relation to muscular activity. Seven healthy adult males performed 200 times body mass-based squat and front lunge exercises. During the exercises, oxygen uptake, heart rate (HR), blood lactate concentration (La), ground reaction force were measured. Oxygen uptake was divided by body mass (VO₂). VO₂ and HR was normalized to maximal VO₂ (%VO₂max) and maximal HR (%HRmax) obtained from an incremental load test. Electromyograms (EMGs) during the two exercises were recorded from the vastus lateralis (VL), rectus femoris, vastus medialis (VM), biceps femoris, gluteus maximus (GM). EMG amplitudes during both exercises were normalized to those during maximal voluntary contraction, and expressed as relative value (%EMG_MVC). Time that cardiorespiratory parameters became stable was 4-6 min in both exercises. VO₂, %VO₂max, metabolic equivalent, were higher in the front lunge than the squat. No significant differences in HR, %HRmax and La were found between both tasks. %EMG_MVC in VL, VM and GM were higher in the front lunge than the squat. These current findings indicate that 1) body mass-based squat and front lunge exercises are physiologically of more than moderate intensity, and 2) the cardiorespiratory responses to body mass-based front lunge are greater than those to body mass-based squat. This may be due to the difference in muscular activities of VL, VM and GM during the tasks.</p>

The relationship between muscle thickness of leg and trunk and the sprint performance in the field and on the cycle ergometer in high school and college students cyclists / 体力科学

The 30-seconds all-out sprint test on the cycle ergometer was performed by 10 high school and 13 college men’s cyclists. In addition, this study investigated their best time for 200 m (200mTT) and 1000 m (1000mTT) time trials in the velodrome. This study clarifies the relationship between muscle thickness of thigh, shank, and trunk and 1) the average speed for the 200mTT and 2) the 1000mTT in the field, and 3) the mean power of the 30-seconds all-out sprint cycling test. 1) The average speed for the 200mTT significantly correlated with the muscle thickness of posterior shank and front and lateral abdomen. 2) The average speed for the 1000mTT significantly correlated with the muscle thickness of posterior thigh and shank and front and lateral abdomen. 3) The mean power of the 30-seconds all-out sprint cycling test significantly correlated with the muscle thickness of anterior and posterior thigh, posterior shank, and front and lateral abdomen. Except for the average speed for the 200mTT and 1000mTT, the mean power of the 30-seconds all-out sprint cycling test was significantly related to the muscle thickness of anterior thigh. These results suggest that increasing muscle thickness of posterior thigh and shank and front and lateral abdomen is important for enhancing performance in sprint cycling.

Influences of body composition, force-generating capacity and jump performance on 50-m sprint velocity in circumpubertal boys / 体力科学

This study aimed to elucidate how body composition, force-generating capacity and jump performances are associated with 50-m sprint velocity in circumpubertal boys, in relation to sprint phases and maturation. One hundred thirty four circumpubertal boys were allocated to preadolescent or adolescent group on basis of the height at the peak height velocity of Japanese boys (154 cm) reported in literature: those with body heights over 154 cm as adolescent group and others as preadolescent group. Body composition was determined by bioelectrical impedance analysis. In addition to maximal voluntary isometric knee extension torque, the performances of counter movement jump (CMJ), rebound jump (RJ), standing long jump (SLJ) and standing 5-step jump (SFJ) were also measured. RJ-index was calculated by dividing height by contact time. The time of 50-m sprint was determined at 10-m intervals. Multiple regression analysis showed that in preadolescent boys, SFJ become a predictor for the sprint speed during acceleration phases, and SFJ, RJ-index and CMJ as predictors for the sprint speeds during maximal speed and deceleration phases. In the adolescent boys, age, CMJ, SLJ, and SFJ become a predictor for the sprint speed during acceleration phases, and torque relative to body mass, CMJ and SFJ were selected as predictors for the sprint speeds during maximal speed and deceleration phases. Thus, the current results indicate that force-generating capacity and jumping ability are determinants for sprint performance in circumpubertal boys, but the relative contribution of each of the two factors differs between preadolescent and adolescent stages and among the sprint phases.

Effect of pre-acclimatization training under hypoxic environment for one week on work capacity and physiological responses under hypoxic environment / 体力科学

We examined the effect of pre-acclimatization training under hypoxia for competition or training at high altitude on work capacity and physiological responses in hypoxia. Eight healthy male university students performed pre-acclimatization training under normobaric hypoxia (equivalent to about 2500 m; 15.4% inspired oxygen) for a week. Each student was exposed for a total of 90 minutes. During the exposure, each student rested for 60 minutes and pedaled at a workload of lactate threshold (LT) under normobaric hypoxia (equivalent to about 2500 m) for 30 minutes. In the result, workload of LT under normobaric hypoxia significantly increased after pre-acclimatization training (+15%). In physiological responses, arterial oxygen saturation at rest and exercise and peak ventilatory volume significantly increased after pre-acclimatization training. Arterial oxygen saturation at rest during pre-acclimatization training significantly increased. In addition, the ratio of low- and high-frequency power in heart rate variability significantly decreased after pre-acclimatization training. These results suggest that pre-acclimatization training is able to bring in acclimatization to high altitude on cardiopulmonary function and prevent decline of work capacity in high altitude. The ratio of low- and high-frequency power in heart rate variability as well as arterial oxygen saturation may reflect degree of acclimatization to high altitude.

Influence of the torque generating capacity of the lower extremity muscles on the running and jump performance in primary and junior high school boys / 体力科学

This study aimed to determine the relationships between the torque generating capacity of the lower extremity muscles and either running or jump performance in primary and junior high school boys. A total of 102 primary and junior high school boys participated in this study. Muscle thicknesses (MTs) of the knee extensors and plantar flexors were determined using ultrasonography. Muscle volumes (MVs) of the knee extensors and plantar flexors were estimated using MTs and limb lengths. The isometric joint torques (TQs) for knee extensors and ankle plantar flexors were measured using myometer. MV and TQ were divided by body mass (MV/BM and TQ/BM, respectively). Running velocity was measured using a non-motorized treadmill. The counter movement jump (CMJ) and squat jump (SJ) were performed on a matswitch system. The flight time was measured and used to calculate the heights of CMJ and SJ using the following equation; height (cm) = g × (flight time)² /8/10. As the result of multiple regression analysis, age, MV/BM and TQ/BM were selected as predictors of running velocity in the primary school boys, whereas TQ and lean body mass in junior high school boys. In the primary school boys, TQ/BM and body fat mass was selected as significant contributors for SJ and CMJ performances, whereas, in the junior high school boys, TQ and the percent of body fat for SJ performance and MV/BM and TQ for CMJ performance. Thus, the present results indicate that the relationships between torque generating capacity of the lower extremity muscles and either running or jump performance differ between primary and junior high school boys. It may be assumed that, for running and jump performances, muscle mass and strength become determinant factors in junior high school boys, whereas their values relative to body mass in primary school boys.

SYSTEMATIC EVALUATION OF THE PHYSIOLOGICAL LOAD OF MOUNTAIN CLIMBING FROM THE RELATION BETWEEN INCLINATION OF WALKING PATH, WALKING SPEED, AND BACKPACK WEIGHT; SIMULATION USING WALKING ON A TREADMILL / 体力科学

We simulated mountain climbing using walking on a treadmill in order to systematically evaluate the physical load during mountain climbing. The conditions of three types of load-(1) inclination of the walking path (walking uphill and downhill), (2) walking speed, and (3) backpack weight-were varied within the range assumed for normal mountain climbing (40 sets of conditions in total). When the three types of load were expressed as vertical work rate, energy expenditure (VO₂) during walking uphill and downhill was distributed along roughly the same curve. The following characteristics of walking uphill and downhill were observed.A. Walking uphillFor all three types of load, increase in load gave a linear increase in VO₂ and heart rate (HR). A lactate threshold (LT) appeared at an intensity of 62%VO_2max, when HR was 78% HR_max. Rating of perceived exertion (RPE) was evaluated for the “Breathlessness” and “Leg Fatigue”, and both of these increased roughly in proportion to %VO_2max.B. Walking downhillWhen walking downhill, VO₂ was 35-50% the intensity of VO₂ when walking uphill on the same slope and at the same speed. Energy expenditure did not exceed 60%VO_2max in any of the load conditions, and no LT was seen. RPE values were higher for walking downhill than walking uphill, even when %VO_2max values were the same. RPE values for the “Leg Fatigue” tended to be higher than for the “Breathlessness” at the same speed in downhill walking.Using these data, we created a table giving the intensity of exercise of mountain climbing expressed as VO₂ per unit body mass and metabolic equivalents (Mets) with vertical migration velocity and total weight (Body weight + Backpack weight) as variables. This table gives mountain climbers a systematic understanding of the physical load under various mountain climbing conditions. It is likely to be of use as a reference for mountain climbers of different levels of physical fitness when practicing mountain climbing appropriate to their individual level. The present results suggest that in downhill walking, it is insufficient to express the physical load in energy expenditure (VO₂ and Mets) alone, and the load on the leg muscles must also be judged using the RPE in the “Leg Fatigue”.

THE RELATIONSHIP BETWEEN THE RUNNING ECONOMY AND THE HOPPING ECONOMY IN THE LONG DISTANCE RUNNER / 体力科学

Running economy is an important factor in determining a performance of a long distance running. The purpose of this study was to examine the relationship between the running economy and the submaximal hopping economy. Twelve long-distance runners performed a submaximal repeated hopping exercise on a force platform at a frequency of 2.2Hz and the maximum five-repeated rebound jumping (5RJ). Jumping height, contact time, maximum ground reaction force and oxygen intake were recorded during submaximal repeated hopping exercise. In addition, they performed the submaximal running for a distance of 3200m on an outdoor 400m track. Oxygen intake was recorded during the submaximal running. Then running economy (RE = V/VO₂) was calculated by using oxygen intake (VO₂) and running speeds (V). Hopping economy (HE = h/VO₂) was calculated by using oxygen intake (VO₂) and average jumping height (h). As a result of this study, we confirmed that a submaximal repeated hopping exercise performed for a ten-minute period was an aerobic exercise and a steady-state exercise. There was a significant positive correlation between RE and HE (r = 0.805, p＜0.01). These results suggest that hopping economy is an important factor in running economy. On the other hand, we did not find a significant correlation between HE and 5RJ. Furthermore, between RE and RJ index of the submaximal hopping exercise, a significant positive correlation was found (r = 0.735, p＜0.01). Therefore, RE seems to be connected with the Stretch-shortening cycle (SSC) function of the legs. We conclude that the SSC ability of a long distance runner can be evaluated appropriately by using the submaximal repeated hopping exercise of this study.

A NATIONWIDE SURVEY OF MIDDLE-AGED MOUNTAINEERS OF JAPAN / 体力科学

The purpose of this study is to help preventing mountaineering accidents. We conducted a questionnaire survey of middle-aged and senior mountaineers (over forty) on a nationwide scale and obtained 3781 significant responses. Both male and female respondents were in their mid-fifties on average. In terms of frequency of mountaineering, the twice-a-month group was the largest one. Approximately 70 percent did physical exercise regularly. Most of the respondents answered that they did not get so tired while mountaineering. However, troubles and/or disabilities while mountaineering occurred in 70% of them. Among them, “ache in the knee”and “wobbly legs”were the most frequent. They seems to be the causes for tumble accidents during descent which is the most common accident in middle-aged mountaineers. According to the results of cross tabulation and chi square testing, 4 items including regular physical training, regular mountaineering, optimum range of BMI (between 21 and 23) and abundant mountaineering experience were the key factors for preventing fatigue and troubles while mountaineering. On the contrary, age and sex were less important factors. However, in the case of some respondents who exercised regularly, they felt fatigue or had troubles while mountaineering. Additionally, some respondents who were confident in their physical fitness did not seem to have enough physical fitness to prevent fatigue and troubles. As stated above, inconsistent relationships were often observed among daily physical training, fatigue and troubles while mountaineering, and confidence in physical fitness, which will be one of the cause of mountaineering accidents.

Effects of stretching, sport massage, light exercise and hot pack on recoveries of work capacity and blood lactate after strenuous exercise / 体力科学

The effects of stretching, sport massage, light exercise (80% of the subjects' anaerobic threshold), and hot pack on the recoveries of work capacity and blood lactate (La) after strenuous exercise were compared with the resting recovery conditions. In each experiment for the four recovery strategies, twelve male physical education students participated as subjects. The subjects performed 5-s maximal effort cycle ergometer exercise bouts, repeated 8 times with 20-s rests (W 1) . A 33-min rest period was given after W 1, and then the same exercise as W 1 was performed again (W 2) . During the rest period (from 9 to 19min after W 1), one of the recovery strategies was practiced for 10min. The subjects also participated in a control experiment (rest recovery) on another day. Blood samples were taken from the earlobe to determine La. The rate of work capacity recovery was significantly higher than the control when stretching was performed, but no significant difference was observed in the recovery rate of La. The same tendency was also observed in the case of sport massage. In the case of light exercise, on the other hand, the recovery rate of La was significantly higher than the control, whereas the recovery rate of work capacity was not significantly different. Many of the subjects complained that the intensity of light exercise was too hard. No significant differences were found in the recovery rates of both work capacity and La by application of a hot pack. These results suggest that stretching and sport massage are effective for accelerating recovery of work capacity. Light exercise was not effective in this study. However, considering previous investigations which showed light exercise to be effective, it might be effective if an abequate work intensity is given. A hot pack is suggested not to be effective. No significant correlation was observed between the recovery rate of La and that of work capacity. Thus it seems that the recovery of work capacity is regulated by factors other than La.