The purpose of this study was to clarify the characteristics of the ability of aerobic and anaerobic power output and the muscle thickness at each site of varsity kayak paddlers. Twenty-three male kayak paddlers who divided into skilled and unskilled group by their career participated in this study. Maximal oxygen uptake as a measure of aerobic power was determined with a progressive arm cranking exercise. Four all-out ergometer work tests lasting 7 and 40 seconds were used to estimate anaerobic alactic power and anaerobic lactic power with leg (pedaling) and arm (cranking) exercises. Anaerobic alactic power (AAP) was computed as the highest power output during 7 seconds and anaerobic lactic power (ALP) was obtained as the mean power output during 40 seconds. Muscle thickness were measured by B-mode ultrasonography at 11 sites on the body. Maximal oxygen uptake of skilled paddlers (3.501/min) was significantly higher than that of unskilled ones (2.701/min) . Similarly, there were significant differences between skilled and unskilled paddlers in AAP and ALP, especially as measured by the arm cranking exercise. The results showed that the career of arm-specific training induced the large specificity of aerobic and anaerobic power output with arm cranking mode. Muscle thickness of skilled paddlers were significantly larger than those of unskilled paddlers at sites on the biceps, abdomen, back muscles, quadriceps and hamstrings, and these strongly correlated with aerobic and anaerobic power output. It is suggested that for the improvement in power output it was necessary to train the muscles of trunk and thigh, and have a specific exercise mode.

Effects of neck muscle training and their changes after discontinuation of training (detraining) were studied in 22 athletes (college American football players) and 19 non-athletes. The subjects underwent narrow grip shoulder shrug training using free weights (NGSS group), isometric training of the neck in pairs (PAIR group), or both types of training (COMB group) for 14 weeks, and were then detrained during the following 14 weeks. Extension and flexion muscle strength (maximum isometric muscle strength) of the neck were measured using a method in which subjects pulled a wire attached over the head in a sitting position at 2-week intervals after the start of training.The following results were obtained.
1. In the athletes, the flexion muscle strength increased by 16.9±5.6% (mean±standard deviation) in the COMB group and by 14.8±5.2% in the NGSS group, and the increases in these groups were significantly greater than the increase in the PAIR group (p<0.01) . The extension muscle strength also increased, most notably in the COMB group (12.2±4.7%) .
2. In the non-athletes, the flexion muscle strength increased by 29.4±7.2% in the COMB group, and this increase was significantly greater than that in the PA1R group (p<0.01) . This increase was also significantly greater than that in the COMB group of the athletes (p<0.01) . The extension muscle strength increased by 19.1±5.2% in the COMB group.
3. In the athletes, the flexion muscle strength of the COMB group was increased by 8.3% after 14 weeks of training and 14 weeks of detraining as compared with that at the start of training. In the non-athletes, the flexion and extension muscle strength of the COMB group increased by 17.4% and 9.8%, respectively, after the start of training.
These results suggest that narrow grip shoulder shrug training used for the development of muscle strength in the lower neck is effective for improving flexion as well as extension muscle strength, and that the decrease in muscle strength due to detraining can be reduced by combining this training with isometric training performed by the PAIR group.

The purpose of this study was to examine the effects of off-season training on the anaerobic power output and muscle thickness of male varsity rowers. 23 rowers participated in this study. Four all-out cycle ergometer work tests lasting 7 and 40 seconds were used to estimate anaerobic alactic power (AAP) and anaerobic lactic power (ALP) with leg (pedaling) and arm (cranking) exercises. AAP was computed as the highest power output during 7 seconds and ALP was obtained as the mean power output during 40 seconds. Muscle thickness was measured by B-mode ultrasonography at 11 sites on the body. There were significant differences between before and after off-season training in AAP (cranking : 8.4±1.00 vs 9.2±1.10W /kg, p<0.001, pedaling: 14.4± 1.10 vs 15.0±1.00 W/kg, p<0.001) and ALP (cranking : 5.2±0.42 vs 5.5±1.20W/kg, p<0.001, pedaling: 10.1±0.62 vs 9.5±2.10 W/kg, n, s.) . Muscle thickness increased significantly as a result of off-season training at sites on the biceps, triceps, pectoralis major, subscaplar and hamstrings. Similarly, there were significant differences in estimated muscle cross-sectional area (MCSA) on sites on the elbow flexor (20.6±2.6 vs 22.1±1.8cm², p< 0.01), elbow extensor (25.3 ±4.8 vs 28.6±4.2cm², p<0.001) and knee flexor (71.1±5.8 vs 74.3±5.2cm², p<0.01) . The main training program in the off-season consisted of resistance training of the whole body. The high intensity training, used by male varsity rowers during off-season training, increased arm AAP, leg AAP, arm ALP and muscle thickness of the upper body ; but there was no difference in leg ALP and knee extensor muscle. It was suggested that improvements in leg ALP and knee extensor muscle are necessary to during the off-season training program of male varsity rowers.

The purpose of this study is to considerate the prediction formula for marathon time based on 20-m shuttle run test and training indexes in recreational runners. 100 male and 111 female recreational runners who have experienced one or more marathon races were measured. Each participant was measured with regard to physical characteristics, 20-m shuttle run test, and answered questionnaires about his/her training (monthly running distance, frequency of training, and years of experience of running training). Moreover, participants self-reported their best marathon time. Additionally, to examine the validity of the prediction formula, 14 male and 13 female recreational runners were measured using the 20-m shuttle run test and they answered the questionnaires about his/her training. The marathon time was significantly correlated with the participant’s BMI, the times of 20-m shuttle run test, the monthly running distance, the frequency of training and the years of experience of running training for both male and female runners. Subsequently, multiple regression analysis generated the prediction model for marathon time by the measurement items. Furthermore, in the examination of the validity of the prediction formula, predicted marathon time was significantly highly correlated with measured marathon time. This study suggested that the marathon time can be predicted by the 20-m shuttle run test, the monthly running distance, and the years of experience of running training and the predicted marathon time may be useful for the marathon race and training in recreational runners.

The purpose of this study was to investigate the relationship between toe muscular strengths and single and/or repetitive jump performances on different directions (vertical or horizontal) in athletes. Thirty two male collegiate students participated (athletes group n=24, control group n=8). Two types of measurements were performed to evaluate toe muscular strengths: toe pushing force (TPF) with the metatarsophalangeal joint (MPJ) at neutral position (0°) and the MPJ in the dorsiflexed position (45°). Jump performances were assessed by press jump (vertical jump and standing broad jump) that measures jumping height or distance, and rebound jump (rebound jump and repetitive hopping) that measures “RJ-index” (the jumping height divided by the contact time). Pearson correlation coefficients were used to determine the relationship between the toe muscular strengths and the performances of each jumping test. There were significant correlations between TPF with the MPJ in the dorsiflexed position and the performances of the repetitive hopping and rebound jump in athletes (P<0.05), but no significant correlations were found in controls. Also, there were no significant correlation between TPF and the performances of vertical jump and standing broad jump of all groups. These results suggest that, TPF in the dorsiflexed positions is one of the indicators that affect repetitive jump performance.