ABSTRACT
The purposes of this study were to investigate the relationships between physical activity variables and physical fitness, and between amount and intensity of physical activity in children and adolescents. Subjects were divided into two groups : 178 children (99 boys aged 9.8±0.6 and 79 girls aged 9.7±0.6) who had not reached the age of peak height velocity (PHV), and 336 adolescents (141 boys aged 15.0±1.1 and 195 girls aged 15.3±1.2) who had reached the age of PHV. Physical activity level (PAL : total energy expenditure/basal metabolic rate) which indicates the amount of physical activity, and time engaged in each of physical activity intensity (light, moderate and vigorous), which indicates the intensity of physical activity were estimated from uni-axial accelerometer. Physical activity was monitored for 3 consecutives days : 2 weekday and 1 weekend day. Moreover, physical fitness test suggested by the Ministry of Education, Culture, Sports, Science and Technology was applied. Results of this study showed that PAL was closely related to physical fitness in children, while time engaged in vigorous activity was more related to physical fitness in adolescents. On the other hand, time engaged in light and moderate activity was closely associated with PAL in younger girls, whereas in younger boys, PAL was closely related to time engaged in moderate and vigorous activity. However, time engaged in moderate activity was more related to PAL in the adolescent group. These results suggest that the relationship between physical activity variables and physical fitness and between amount and intensity of physical activity might vary according to the growth development of boys and girls respectively.
ABSTRACT
The present study examined the effect of the long-term intake of chicken breast extract (CBEX), which contains carnosine and anserine, on carnosine content in skeletal muscles of humans and on short-period exercise performance with high intensity.<BR>Before and after CBEX was orally given to 13 healthy male subjects for 30 days, pieces of their muscle (<I>M. vastus lateralis</I>) were excised and carnosine concentration in the muscle was measured. Before and after the test period, the subjects exercise performance (mean and peak power body weight) was determined by pedaling for 30 sec. On the basis of baseline concentrations of carnosine, the subjects were classified into two groups: low (n=8) and high (n=5) carnosine-baseline groups. In the former group, intake of CBEX increased carnosine concentration in the muscle (p<0.05), resulting in significant correlation between increased rate of carnosine concentration and mean power. These results suggest that exercise performance depends on carnosine concentration in the muscle, and that taking carnosine-containing foods may improve exercise performance.
ABSTRACT
The purpose of this study was to investigate the effects of different sitting postures, by change of seat height, on lower extremity muscle activation and maximum power during explosive bicycle pedaling exercises. The subjects performed 5 sec maximum pedaling exercises at three different seat heights.‘High’ seat height was defined as 95% of leg length, ‘Middle’ was 90% and‘Low’ was 85%.<BR>The results were summarized as follows: A) At 3 revolutions, maximum power at‘High’ was significantly higher than that at‘low’. B) Pelvic angle at‘High’ was significantly higher than that at‘Low’. C) The maximum extension angle of the knee joint was a significantly high value in descend. ing order of‘High’, ‘Middle’ and‘Low’. D) mEMG of the Erector spinae and Biceps femoris at‘High’ was significantly higher than that at‘Low’. E) At‘High’, there was a significant correlation between maximum power of 3 revolutions and mEMG in the Gluteus maximus. In addition, maximum power at 3 revolutions tended to correlate with mEMG in the Biceps femoris and Vastus lateralis.<BR>These results suggest that in explosive pedaling exercises, different sitting postures by change of seat height, have different influences on hip extension muscle activation and maximum power.
ABSTRACT
It is known that lactic anions and hydrogen ions (H<SUP>+</SUP>) produced during intense exercise are partly transported or diffused from muscle to blood resulting in the production of non-metabolic CO<SUB>2</SUB> through the bicarbonate buffering system. The purpose of the present study was to examine the reliability of the estimation of non-metabolic CO<SUB>2</SUB> output using respiratory gas analysis during incremental exercise. Six healthy subjects underwent an incremental pedaling exercise test accompanied by respiratory gas and arterial blood sampling. The rate of non-metabolic CO<SUB>2</SUB> output (VCO<SUB>2</SUB>-NM) was calculated by subtracting projected metabolic VCO<SUB>2</SUB> from actual VCO<SUB>2</SUB> after CO<SUB>2</SUB> threshold (CT) . CT was determined using a modified V-Slope method. Bicarbonate (HCO<SUB>3</SUB><SUP>-</SUP>), pH, CO<SUB>2</SUB> partial pressure and lactate concentration were measured from arterial blood samples using automatic analyzers. The kinetics of VCO<SUB>2</SUB>-NM and HCO<SUB>2</SUB><SUP>-</SUP> were compared throughout the exercise test. VCO<SUB>2</SUB>-NM was significantly correlated with HCO<SUB>3</SUB><SUP>-</SUP>decrease after CT (r=0.976, p<0.001) and the kinetics of VCO<SUB>2</SUB>-NM and HCO<SUB>3</SUB><SUP>-</SUP> decrease were similar during exercise. Furthermore, the amount of non-metabolic CO<SUB>2</SUB> output (NM-CO<SUB>2</SUB>) calculated integrating VCO<SUB>2</SUB>-NM above CT was significantly correlated with the difference in HCO<SUB>3</SUB><SUP>-</SUP>between CT and exhaustion (r=0.929, p<0.01) and with the difference in arterial blood pH between rest and exhaustion (r=0.863, p<0.05) . However, NM-CO<SUB>2</SUB> was not significantly related to maximum ventilation (r=0.111, ns) . These results suggest that the estimation of non-metabolic CO<SUB>2</SUB> output during incremental exercise proposed in the present study is reliable. It was also suggested that the primary factor which influenced nonmetabolic CO<SUB>2</SUB> output during incremental exercise was the addition of H<SUP>+</SUP> into blood and not hyperventilation.
ABSTRACT
The purpose of the present study was to determine the change in total excess volume of CO<SUB>2</SUB>output (CO<SUB>2</SUB>excess) due to bicarbonate buffering of lactic acid produced during exercise and change in swimming performance following resistance training for 8 weeks in competitive swimmers. Ten healthy university competitive swimmers were assigned to either a resistance training and swimming training group (COMBINE: N=5) or a swimming training only group (SWIM: N=5) . Muscle mass was measured using magnetic resonance imaging (MRI) . CO<SUB>2</SUB>excess and blood lactate concentration were measured during incremental exercise on a cycle ergometer and swimming performance was measured during competition. COMBINE showed a significantly higher percentage change in muscle mass (11.1±4.5%) than SWIM (3.5±2.5%) . The percentage change in CO<SUB>2</SUB>excess, CO<SUB>2</SUB>excess per body weight (CO<SUB>2</SUB>excess/BW) and CO<SUB>2</SUB>excess/BW per blood lactate accumulation (CO<SUB>2</SUB>excess/BW/ΔLa) during exercise was significantly higher in COMBINE (107.3±60.1, 102.6±56.8, 59.1±37.7%, respectively) than in SWIM (42.5±10.0, 42.9±10.4, 13.4±22.4%, respectively) . The percentage change in swimming performance was significantly higher in COMBINE (2.2±1.8%) than in SWIM (-2.0±3.6%) . A negative correlation between percentage change of muscle mass and percentage change of CO<SUB>2</SUB>excess/BW/ ΔLa (SWIM: r=-0.993, <I>P</I><0.01, COMBINE: r=-0.744, <I>P</I>>0.05) was found. It was suggested that combined swim and resistance training resulted in greater increases in the bicarbonate buffering system (CO<SUB>2</SUB>excess/BW/ΔLa) . However, increases in muscle mass may have subsequently caused a relative decrease in the contribution of the bicarbonate buffering system.
ABSTRACT
This study investigated the relationship of high-power work capacity with physiological variables during supramaximal intermittent exercise and individually measured alactic (ATP-CP), lactic (LA), and oxygen (O<SUB>2</SUB>) energy delivery systems. Nineteen university handball players (experiment 1) and 23 university basketball players (experiment 2) performed an intermittent exercise routine consisting of a combination of high-power and low-power exercise. The exercise protocols were a laboratory test consisting of pedaling on a bicycle ergometer (experiment 1) and a field test consisting of a running protocol incorporating changes in direction (experiment 2) . The main results were as follows :<BR>(1) The ATP-CP system was significantly related to power output during the early stage of intermittent exercise and the O<SUB>2</SUB> system was significantly related to power output in the middle and late stages of intermittent exercise. As an indicator of the O2 system, blood lactate concentration during submaximal exercise correlated more closely with power output during intermittent exercise compared with VO<SUB>2</SUB>max/BW. The LA system was not significantly related to power output during intermittent exercise.<BR>(2) Subjects were divided into 2 groups according to energy delivery ability and then power output ability during intermittent exercise was compared. The high ATP-CP system group had a significantly higher power output during the early stage of intermittent exercise compared with the low ATP-CP system group. The high O<SUB>2</SUB> system group had a significantly higher power output in the middle and late stages of intermittent exercise compared with the low O<SUB>2</SUB> system group. Compared to the low O<SUB>2</SUB> system group, the high O<SUB>2</SUB> system group had a higher absolute VO<SUB>2</SUB> during the low intensity active recovery periods of intermittent exercise, as well as a tendency to have lower blood lactate levels. The high LA system group showed lower power output over the course of intermittent exercise compared with the low LA system group.<BR>These results indicate that the O<SUB>2</SUB> system is important for exerting higher power output during supramaximal intermittent exercise.
ABSTRACT
To obtain a viewpoint concerning evaluation of endurance type of athletes, we investigated the difference in physiological responses between middle- and long-distance runners in an incremental running test. Measurements were VO<SUB>2</SUB>max and time of its appearance, change of VO<SUB>2</SUB> from 1.5 min before exhaustion to exhaustion (ΔVO<SUB>2</SUB>), heart rate (HR), and blood lactate after exhaustion.<BR>Results were as follows.<BR>(1) The time of VO<SUB>2</SUB> max appearance in the middle distance runners was earlier than in the long distance runners.<BR>(2) VO<SUB>2</SUB>max was significantly higher in the long distance runners than in the middle distance runners.<BR>(3) Blood lactate after exhaustion and HRmax were significantly higher in the middle distance runners than in the long distance runners.<BR>(4) Blood lactate after exhaustion was significantly related to ΔVO<SUB>2</SUB> (r =-0.660, P<0.05) .<BR>These findings suggest that the endurance type of athletes could be evaluated from the time of VO<SUB>2</SUB>max appearance, blood lactate after exhaustion and HRmax in incremental running, and that VO<SUB>2</SUB>max appearance may be effected by high blood lactate accumulation.
ABSTRACT
The purpose of the present study was to investigate the relationships between the peak running velocity, and aerobic and anaerobic capacity in incremental running in pre- and post-competitive season using eight long distance runners. Measurements were peak running velocity, VO<SUB>2max</SUB>, running velocity and VO<SUB>2</SUB> at respiratory exchange ratio (RER) 1.0, and blood lactate after exhaustion in the incremental running test. Correlation analysis revealed that pre-season velocity at RER 1.0 and post-season blood lactate were both related to peak running velocity. Furthermore, change in peak running velocity was related to change in blood lactate between pre-and post-season. These results suggest that factors that probably influenced running performance change from aerobic capacity in the pre-season to anaerobic capacity in the post-season, and that running performance during the competitive season may be highly dependent upon anaerobic capacity.
ABSTRACT
The purpose of the present study was to investigate the effect of lactate accumulation on oxygen uptake immediately before exhaustion during anaerobic-aerobic maximal running. The present study focused on the relationship between change of oxygen uptake and blood lactate during the latter phase of maximal running. Eleven middle and long distance runners performed 4-min (submaximal) and 6-min (maximal) running at the same running speed. In a series of tests, oxygen uptake (VO<SUB>2</SUB>), ventilation (VE), heart rate (HR), and blood lactate (LA) were measured. In addition, differences (Δ) between maximal and submaximal values in each parameter were calculated. AVO<SUB>2</SUB> was significantly related to ΔLA (r=0.670, P<0.05) . This finding suggests that increased oxygen uptake may be due to increased lactate accumulation during the latter phase of anaerobic-aerobic maximal running.
ABSTRACT
A training experiment was carried out to investigate the difference in training effects between power-up type and bulk-up type strength training exercises from the aspects of muscle histochemical properties and capillary supply. The subjects were eleven healthy males. The power-up type group (five males) performed knee extension exercise for 5 sets at 90% of 1 RM (one repetition maximum) with a 3-min rest between sets (repetition method) . The bulk-up type group (six males) performed the same exercise for 9 sets at 80-40% of 1RM with a 30-s or 3-min rest between sets (interval method, multi-poundage system) . Both programs were carried out twice a week for 8 weeks.<BR>The main results were as follows ;<BR>1. Percentages of fiber types showed no recognizable changes in either group.<BR>2. Fiber area was significantly increased for all fiber types (Type I, Type IIA, Type JIB) in both groups. However, the rate of increase was greatest for type IIA fiber, followed by type JIB fiber and then type I fiber. Moreover, the rate of increase for all fiber types in the bulk-up group was higher than that in the power-up group.<BR>3. Percentage of fiber area showed no recognizable changes for any fiber types in the powerup group. However, the percentage area of type II fibers, especially type IIB fiber, was significantly decreased in the bulk-up group.<BR>4. CC (Type I), CC (Type IIA) and CC (Type IIB) (number of capillaries in contact with each fiber type) were significantly increased in both groups. However, in comparison with CC (Type I), CC (Type IIA · Type IIB) showed a higher rate of increase in the power-up group. On the other hand, in comparison with CC (Type IIA · Type JIB), CC (Type I) showed a higher rate of increase in the bulk-up group. Also, compared with the power-up group, the bulk-up group showed a signifi-cantly higher rate of increase of CC (Type I) .<BR>5. C/Fiber area (Type I), C/Fiber area (Type IIA) and C/Fiber area (Type IIB) (number of capillaries supplying each fiber area) were decreased in both groups.<BR>The above results show that power-up type exercise leads mainly to hypertrophy of type I, type IIA and type IIB fibers without any change in percentage fiber type or percentage fiber area, whereas bulk-up type exercise leads mainly to hypertrophy of each fiber type with decreases in percentage area of type II fibers, especially type JIB fiber. Also, power-up type exercise leads mainly to an increase in the number of capillaries around type II fibers, whereas bulk-up type exercise leads mainly to an increase in the number of capillaries around type I fiber. However, capillary development around all fiber types did not necessary coincide with muscle hypertrophy in either exercise.<BR>The authors reported previously that power-up type exercise is effective mainly for improving muscular strength and anaerobic power, whereas bulk-up type exercise is effective mainly for induc. ing hypertrophy and anaerobic endurance. The results of this study may help to clarify these effects from the viewpoint of the adaptations of muscle fibers and the capillary supply.
ABSTRACT
In this study, the difference between the effects of “power-up type” and “bulk-up type” strength training exercise was investigated by analyzing parameters such as structural and functional adaptations in the neuromuscular system. Eleven subjects were divided into power-up and bulk-up groups. The power-up group comprised five male subjects who performed 5 sets at 90% of one repetition maximum (1 RM) with a 3-min rest between sets (repetition method) . The bulk-up group comprised six male subjects who performed 9sets at 80-60-50%, 70-50-40%, and 60-50-40% of 1 RM with rest intervals between sets of either 30 s or 3 min (interval method) . Both groups performed isotonic knee extension exercise twice a week for 8 weeks. The power-up group showed a lower rate of improvement than the bulk-up group in terms of cross-sectional area (CSA) of the quadriceps femoris at levels 30%, 50% and 70% from the top of the femur, and also in average isokinetic strength (Isok. ave. ; 180 deg/s, 50 consecutive repetitions) . However, the power-up group showed a greater rate of improvement in 1 RM, maximal isometric strength (Isom. max), and maximal isokinetic strength (Isok. max ; 60, 180, 300 deg/s) . Furthermore, the rate of reduction in strength over 50 consecutive isokinetic repetitions decreased in the bulk-up group. On the other hand, the power-up group showed no significant changes in the above throughout the entire training program. These results indicate that the characteristics of the two types of training exercise are as follows : (1) power-up exercise is effective mainly for improving muscular strength and anaerobic power, and (2) bulk-up exercise is effective mainly for improving hypertrophy and anaerobic endurance. These findings support the idea that “power-up type” and “bulk-up type” strength training exercises should be applied appropriately according to the training aim.
ABSTRACT
Bone (tibia, femur, and lumbar spine) and blood samples were obtained from 100 (50 males and 50 females) Wistar-Imamichi rats in groups aged 3, 5, 7, 9, 12, 15 and 20 weeks old to investigate the changes in bone mass during puberty in relation to insulin-like growth factor 1 (IGF-1), IGF binding protein (IGFBP) -3, osteocalcin (OC) and sex steroids in normal rats.<BR>Sharp increases in BMD (bone mineral density) in the tibia, femur and lumbar appeared earlier in female than in male rats, and the BMD in females tended to be higher than in males between 5 and 9 weeks old. After 9 weeks old, BMD in males was higher than that in females, as BMD in males continued to increase whereas that in females tended to remain in a steady state after this stage. This sex-related difference in changes in BMD pattern is probably related to the serum concentrations of IGF-1, IGFBP-3, testosterone, and 17β-estradiol with maturation. In males, marked increases in serum IGF-1 and IGFBP-3 concentrations appeared earlier than that in serum testosterone level. IGF-1 and testosterone peaked at 9 weeks of age, and thereafter remarked in a steady state, whereas IGFBP-3 reached a peak at 7 weeks of age, and then declined gradually. In females, the changes in patterns of serum 17β-estradiol, IGF-1, and IGFBP-3 levels were very similar. The levels increased gradually from 3-5 weeks old, peaked at 9 weeks, and then decreased slowly thereafter. In contrast, serum OC concentrations remain relatively high from 3 to 9 and from 3 to 7 weeks old in males and females, respectively, although OC in both sexes declined gradually with aging.<BR>These observations suggest that BMD development occurs earlier in female than in male rats. This sex-related difference in changes in the BMD pattern may result from the earlier onset of puberty in females, and from the sex-specific differences in concentrations of IGF-1, IGFBP-3 and sex steroids with maturation.
ABSTRACT
Physical activity in the growing period has been shown to be effective for increasing bone mass because immature bones are more sensitive than mature adult bones to the stimulation with mechanical stress. However, bone growth is not uniform and changes markedly at puberty. Therefore, the response of bone to exercise may differ according to the growth process. The purpose of the present study was to investigate the process of the bone response to running training, and the relationship between the bone response and serum insulin-like growth factor-I (IGF-I) and IGF binding protein-3 (IGFBP-3) levels in female rats. Thirty-three female Wistar-Imamichi rats 4 weeks of age were divided randomly into control (CON) and running training (RUN) groups for 6 and 12 weeks. Training consisted of running on a flatbed treadmill at 30 m/min for 60 min/day, 5 days/week. The bone mineral content (BMC) and bone mineral density (BMD) in the whole and five parts of the tibia were measured by a dual-energy X-ray absorptiometer (DXA) . Simultaneously, we measured serum concentrations of IGF-I, IGFBP-3, osteocalcin and 17β-estradiol. The whole tibial BMD was significantly higher in the RUN groups than in the age-matched CON groups. When BMD was analyzed at five different studied parts within the same tibia, the increase of BMD. was noted in the proximal and distal cancellous bone in the 6-week RUN group, and in the diaphysial, cortical bone, in the 12-week RUN group. Serum concentrations of osteocalcin, a marker of bone formation, were not altered by training, whereas they decreased with aging. Serum IGF-I levels in the training groups were not changed, but IGFBP-3 levels were increased significantly only in 6-week RUN rats. As a complex between IGFBP-3 and IGF-I may be more improve than free IGF-I in the bone formation, the high levels of IGFBP-3 in the 6-week RUN group may induce an increase in the activity of IGF-I. There was a significant positive relationship between serum IGF-I concentration and BMD of the whole tibia in the 6-week study, and between the IGFBP-3 level and BMD in both the 6 and 12-week studies.<BR>In conclusion, 1) the process of the skeletal response to running training is site-specific within the same bone, and 2) the increment of the IGFBP-3 level with training in the growth period may reflect the increment of tibial BMD through training.
ABSTRACT
This study clarified the most appropriate landing motion for enhancement of the rebound drop jump index (RDJ<SUB>index</SUB>), which can evaluate the ability to perform ballistic and stretch-shortening cycle (SSC) movements. The RDJindex was calculated using the formula RDJ<SUB>index</SUB>= (1/8⋅g⋅RDJt<SUB>a</SUB><SUP>2</SUP>) /RDJt<SUB>c</SUB> where RDJt<SUB>c</SUB> and RDJt<SUB>a</SUB> are the contact and air times during a rebound drop jump from a height of 0.3 m (RDJ), a typical SSC movement. The relationships between the RDJ<SUB>index</SUB> and the characteristics of the knee and ankle joint motions during RDJ were examined in nine male jumpers. The results were as follows:<BR>(1) The characteristics of leg motion during the descending phase were that the ratio (%K-ANG) of displacement in flexion of the knee during the descending phase to that during both descending and takeoff phases was 48.6% and this preliminary motion started 53.6 ms before touchdown. Furthermore, as %K-ANG increaced, the contact time decreased (r=-0.784, p<0.05), the air time increased (r=0.874, p<0.01) and consequently, the RDJ<SUB>index</SUB> increased (r=0.891, p<0.01) . These results suggested that quick knee flexion just before touchdown is an important factor in increasing the RDJ<SUB>index</SUB>.<BR>(2) A characteristic of the leg motion during the takeoff phase was that the end point of knee flexion appeared 13.3 ms earlier than that of ankle dorsiflexion. That time increased as %K-ANG increaced (r=0.830, p<0.01), but conversely, as %K-ANG decreased markedly, end point of ankle dorsiflexion appeared earlier than that of knee flexion. These results suggested that preliminary motion of the knee would result in appropriate timing of the knee and ankle motions for shock absorption during the takeoff phase of RDJ.<BR>(3) An other characteristic of the leg motion during the takeoff phase was that the ratio of displacement of the knee in extension to that in flexion was 310.2%. This ratio increased as %K-ANG increaced (r=0.903, p<0.001) . These results suggested that preliminary motion of the knee would cause to increase displacement in extension for kick motion and yet to decrease displacement in flexion for shock absorption.<BR>These findings led to the conclusion that quick and short range flexion at the knee just before touchdown was an effective landing motion for enhancing the ability to perform ballistic and SSC movements.
ABSTRACT
The purpose of this study was to investigate the effects of running training on bone formation in rats in relation to the age training started. The first experimental period was set from 6 to 12 weeks (wks) old and the second from 12 to 19 wks old. Sixty-four Wistar strain 6-wk-old male rats were initially divided into a non-exercise (N) and an exercise (E) group. At 12 wks old, each group was subdivided into two groups, providing four groups: non-exercise·non-exercise (NN), non-exercise·exercise (NE), exercise·non-exercise (EN) and exercise·exercise (EE) . Exercise consisted of treadmill running at a speed of 30 m/min, 60 mm day, 5 days wk. The animals were sacrificed before the experiment (6 wks old), post-first experiment (12wks old) and postexperiment (19 wks old), the bilateral tibiae were removed and their lengths, bone mineral content (BMC), bone mineral density (BMD) and bone histomorphometric parameters were measured. The tibial length was significantly shorter in 12-wk-old E than N rats and in 19-wk-old EE than NN. At 19 wks old, the total tibial BMD values were significantly higher in EE than NN, and the BMD values of the proximal and distal tibiae, where the cancellous bone was the main component, had increased markedly, whereas no differences between the diaphyseal BMD of each group were noted. Bone histomorphometry at 12 wks old, considered the immature period, showed that the osteoid surfaces and labeled surfaces tended to be increased by running training, but the bone volume was unchanged. In contrast, at 19 wks old, considered the early mature period, the osteoid surfaces showed a tendency to decrease and labeled surfaces to increase and consequently the bone volume increased albeit not significantly. These results suggest that: 1) running training started in immature rats represses longitudinal tibial growth, 2) the cancellous bone is more sensitive then the cortical bone to this type of training and 3) training of early mature rats increases bone volume by increasing the efficiency of osteoid calcification.
ABSTRACT
Long jump and high jump, and several types of jumping and footwork with rapid changes in speed and direction of movement in ball games are characterized not only by a combination of eccentric and concentric movement (stretch-shortening cycle movement, SSC) but also a ballistic movement of very short duration (100-200 ms) . This study was conducted to examine the effects of strength and power on ballistic stretch-shortening cycle movement (BSSC) ability to clarify the methods of strength and power training necessary for jumpers and ball game players. The subjects were 99 male college athletes. The index for BSSC ability was RDJ<SUB>index</SUB> [RDJ<SUB>index</SUB> = (1/8⋅g⋅RDJt<SUB>a</SUB><SUP>2</SUP>) /RDJt<SUB>c</SUB>] which was calculated using contact time (RDJt<SUB>c</SUB>) and air time (RDJt<SUB>a</SUB>) in a rebound drop jump from a height of 0.3 m with a small angular range of motion for the knee. The index for strength was maximum leg extension strength exerted in a squat position at a 90° knee angle (Smax/BW) . The index for power was the height of a counter movement jump (CMJh) . Results were summarized as follows;<BR>(1) There were significant correlations between RDJ<SUB>index</SUB>and Smax/BW (r=0.219, p <0.05), RDJ<SUB>index</SUB>and CMJh (r=0.584, p<0.001), and Smax/BW and CMJh (r=0.487, p<0.001), but they were fairly low, suggesting that these indices do not have similar significance for estimating training effects and sports talent.<BR>(2) There was no significant correlation between RDJt<SUB>c</SUB>and RDJt<SUB>a</SUB>, of which the RDJ<SUB>index</SUB>was composed (r=-0.145, ns) . This result suggests that BSSC ability consists of two independent abilities, i. e. the ability to jump higher and the ability to shorten one's movement time.<BR>(3) There were significant correlations between RDJt<SUB>a</SUB>and Smax/BW (r=0.340, p<0.001), RDJt<SUB>a</SUB>and CMJh (r = 0.647, p <0.001), but not RDJt<SUB>c</SUB>and Smax/BW (r=0, 035, ns), or RDJt<SUB>c</SUB>and CMJh (r=-0.187, ns), suggesting that the ability to jump higher is affected by strength and power whereas the ability to shorten one's movement time is not.<BR>(4) When subjects with equal RDJ<SUB>index</SUB>were compared, one subject was dominant in RDJtc and another in RDJt<SUB>a</SUB>. This result suggests that we should consider individual differences based on RDJt<SUB>c</SUB>and RDJt<SUB>a</SUB>in training for increasing the RDJ<SUB>index</SUB>.<BR>These findings seem to be useful to clarifying the methods of strength and power training for jumpers and ball game players who need to improve their ballistic stretch-shortening cycle movement ability.