This study was carried out to compare blood lactate changes in isocapnic buffering phase in an incremental exercise test between sprinters and long distance runners, and to seek the possibility for predicting aerobic or anaerobic potential from blood lactate changes in isocapnic buffering phase. Gas exchange variables and blood lactate concentration ([lactate]) in six sprinters (SPR) and nine long distance runners (LDR) were measured during an incremental exercise test (30 W·min-1) up to subject's voluntary exhaustion on a cycle ergometer. Using a difference between [lactate] at lactate threshold (LT) and [lactate] at the onset of respiratory compensation phase (RCP) and the peak value of [lactate] obtained during a recovery period from the end of the exercise test, the relative increase in [lactate] during the isocapnic buffering phase ([lactate]ICBP) was assessed. The [lactate] at LT (mean ± SD) was similar in both groups (1.36 ± 0.27 for SPR vs. 1.24 ± 0.24 mmol·l-1 for LDR), while the [lactate] at RCP and the peak value of [lactate] were found to be significantly higher in SPR than in LDR (3.61 ± 0.33 vs. 2.36 ± 0.45 mmol·l-1 for RCP, P<0.001, 10.18 ± 1.53 vs. 8.10 ± 1.61 mmol·l-1 for peak, P<0.05). The [lactate]ICBP showed a significantly higher value in SPR (22.5 ± 5.9%, P<0.05) compared to that in LDR (14.2 ± 5.0%) as a result of a twofold greater increase of [lactate] from LT to RCP (2.25 ± 0.49 for SPR vs. 1.12 ± 0.39 mmol·l-1 for LDR). In addition, the [lactate]ICBP inversely correlated with oxygen uptake at LT (VO2LT, r=-0.582, P<0.05) and maximal oxygen uptake (VO2max, r=-0.644, P<0.01). The results indicate that the [lactate]ICBP is likely to give an index for the integrated metabolic, respiratory and buffering responses at the initial stage of metabolic acidosis derived from lactate accumulation.
The purpose of this study was to examine the useful measurement time when evaluating static muscle endurance by comparing various parameters during sustained static gripping for 1, 3 and 6 min. Fifteen males (mean ± SD age 20.8 ± 1.3 yr, height 172.9 ± 4.6 cm, body mass 67.7 ± 5.7 kg) and fifteen females [mean ± SD age 20.2 ± 0.9 yr, height 158.5 ± 3.2 cm, body mass 55.9 ± 4.6 kg] volunteered to participate in this study. The subjects performed the sustained static maximal grip test with a sagittal and horizontal arm position for 1, 3 and 6 min on different days. Eleven force-time parameters were selected to evaluate static muscle endurance. The trial-to-trial reliability of each measurement time of sustained static maximal gripping was very high (rxy = 0.887-0.981 (1 min), 0.912-0.993 (3 min), 0.901-0.965 (6 min)). The errors of exertion values between trials were very small (below 10%). A significant correlation was found in the following parameters: the final strength and the exponential function between 1 min and 3 min, all parameters except for the time required to reach 80% of maximal grip, the regression coefficient at post-inflection between 3 min and 6 min, and the decreasing rate between all measurement times (1 min, 3 min, and 6 min). Significant differences between the measurement times were found in all parameters except for the time to 60, 70, and 80 % force decreases, and the regression coefficient of pre-inflection. There was a tendency that the longer the measurement time, the larger the decreasing force. It is suggested that for the 6 min measurement, the subjects unconsciously restrained the maximal gripping force, influenced by a psychological factor as the pain became greater. The 1 min measurement may evaluate only the remarkable decreasing phase of the decreasing force, and not evaluate the phase of an almost steady state.
We investigated the effects of laughing and weeping induced by watching comedy and tragedy videos on mood and autonomic nervous function. Ten healthy female subjects volunteered for the experiment. Chest electrocardiogram and respiration curve were recorded before, after, and during watching a comedy or a tragedy video. We also asked them to fill out profiles of mood states (POMS) to evaluate their mood states while watching videos. Autonomic nervous function was estimated by spectral analysis of heart rate variability (HRV). All subjects more or less laughed and wept while watching comedy and tragedy videos, respectively. Anger-hostility score of the POMS decreased and vigor score increased significantly after watching comedy videos, while depression-dejection score increased significantly after watching tragedy ones. Although both contents tended to increase a low to high frequency component ratio (LF/HF ratio) of HRV, the time course of responses was different. The LF/HF ratio which reflects cardiac sympathovagal balance increased immediately after they started watching comedy videos, and returned to the basal level right after they stopped watching, whereas the LF/HF ratio increased gradually to a lesser extent while watching tragedy videos. In contrast, the high-frequency component which reflects cardiac parasympathetic nerve activity gradually decreased while watching both videos but did not return to the basal level after watching tragedy ones. These results suggest that laughing has strong but transient effects on the autonomic nervous system, while weeping or feeling sad has moderate but sustained effects on it.
The purpose of the present study was to examine the interrelationship of achievement patterns between 74 activities by selecting nine ADL domains, including 27 items used in existing ADL index for the institutionalized disabled elderly (Disabled-ADL). For these 74 ADL items, 706 institutionalized dependent elderly were assessed using a dichotomous scale of "possible" or "impossible" by staff working at the subjects' institutions. The difficulty of each item was examined by calculating the proportion of "possible" responses. The interrelationships among activities were determined by calculating φ coefficients. Furthermore, the degree of agreement assessed between ADL items was calculated by dividing the total response by the number of "possible-possible" and "impossible-impossible" responses, in order to examine the similarity of the achievement pattern of ADL. The φ coefficient values were high among ADL items with comparable difficulty where the item proportions were within about 10%. Even if belonging to a different ADL domain, the relationship was high among ADL items with similar difficulty and kinds of activity. All of the 27 activities used in Disabled-ADL indicated high agreement of over 80% with one or more activities among the other 47 activities used in this study. Especially, three lower extremity activities of "putting on trousers while standing", "going up and down stairs" and "squatting down from a standing posture" agreed more than 90% with many other lower extremity activities. The possibility is suggested in determining lower extremity functional levels by assessing these three activities. The selection of ADL items considering these influences is necessary to comprehensively assess ADL ability of disabled elderly.