Assessment of long-distance running performance in elite male runners using onset of blood lactate accumulation.

The purpose of this study was to evaluate the relationship between onset of blood lactate accumulation (OBLA) and long-distance running performance in order to examine whether OBLA can be a good predictor of long-distance running performance even in elite male runners with similar performance levels. Eleven highly-trained male long-distance runners participated in this study. The average running velocities of the individuals' running performance were 5.918 +/- 0.084 m.s-1 and 5.672 +/- 0.095 m.s-1 for 5000 m (V5000) and 10,000 m (V10000), respectively. The blood lactate concentrations and heart rate responses were measured immediately after field running, and the average value of running velocity corresponding to OBLA (VOBLA) was 5.447 +/- 0.132 m.s-1. Variations of these three velocities expressed as a coefficient of variance (CV) ranged from 1.4 to 2.4%. A strong inverse relationship between heart rate corresponding to OBLA (HROBLA) and performance was observed (r = -0.709, p < 0.02 for V5000 and r = -0.830, p < 0.01 for V10000), while there was a lack of significant relationship between VOBLA and performance (r = 0.293, NS for V5000 and r = 0.130, NS for V10000). Furthermore, the average value of HROBLA obtained in this study (174.5 +/- 8.2 b.min-1) was quite similar to that of the heart rate threshold reported by some previous researchers. In conclusion, VOBLA alone could not explain the small variation of long-distance running performance, and HROBLA should be used in place of VOBLA for evaluating long-distance running performance in elite runners with quite similar performance levels.

Efficient screening for catalytic antibodies using a short transition-state analog and detailed characterization of selected antibodies.

One of the major obstacles to acquiring catalytic antibodies is that it requires labor-intensive procedures to select catalytic antibodies from huge repertories of antibodies. Here, we selected potential catalytic Abs by utilizing their affinity towards a short transition-state analog which contained only the transition-state structural element, and evaluated in detail its efficiency to enrich catalytic Abs. Hybridoma supernatants elicited against a phosphonate derivative, the TSA1, were screened by a three-step screening process: step 1, ELISA for TSA1-BSA; step 2, ELISA for the short TSA4; and step 3, competitive-inhibition by the short TSA2. Only 22. 8% of positive mAbs from step 1 were found to be catalytic. The rate of catalytic Abs increased to 45.7% using screening steps 1 plus 2, and reached 83.3% using all three screening steps. This clearly suggests that our screening protocol is an efficient method to select potential catalytic Abs. Furthermore, we characterized the properties of both the catalytic Abs and the noncatalytic Abs in detail. The catalytic Abs tended to have lower Kd for TSA1 and the short TSA2 than noncatalytic Abs. It was also observed that catalytic Abs showed clear enantiospecificity toward substrate 6 containing d-phenylalanine while noncatalytic Abs did not. The detailed analysis of kinetic and binding parameters for these antibodies gives us further insight into catalytic antibodies.

Effects of exhaustive exercise on biochemical characteristics of sarcoplasmic reticulum from rat soleus muscle.

This study examined the effects of acute high-intensity and moderate-intensity exercise on Ca2+-stimulated adenosine triphosphatase (ATPase) activity and the Ca2+ and ATP dependence of Ca2+-ATPase of the sarcoplasmic reticulum (SR) in the soleus muscle. The rats were run on 10% grade at 50 m min(-1) or 25 m min(-1) until fatigued (avg. time to exhaustion 2.8 and 87.7 min, respectively). The catalytic activities of SR Ca2+-ATPase were significantly depressed immediately after both types of exercise. Kinetic analyses demonstrated that the Ca2+ affinity of Ca2+-ATPase was elevated by both types of exercise adopted in the present investigation whereas the increase in the ATP affinity was brought about by only high-intensity exercise. These results suggest that exhaustive exercise may induce in slow-twitch muscle fibre the environmental changes, which adversely affect SR Ca2+-ATPase activity and can overcome the positive influence arising from the increase in the Ca2+ and/or ATP affinities of SR Ca2+-ATPase.

Expression of hybrid isomyosins in human skeletal muscle.

Myosin of human skeletal muscles was analyzed by means of several electrophoretic techniques. Myosin heavy chain (HC)-IIa-and HC-IIb-based isomyosins were identified by pyrophosphate-polyacrylamide gel electrophoresis (PP-PAGE). The electrophoretic mobilities of these fast-twitch muscle isomyosins differed in the order HC-IIa triplets < HC-IIb triplets. To determine the subunit composition of myosin molecules that function in intact muscle, two-dimensional electrophoresis in which the first and second dimensions were PP-PAGE and sodium dodecyl sulfate-PAGE, respectively, was also performed. Slow-twitch muscle isomyosin contained, in addition to slow-twitch light chain (LC) and HC-I isoforms, appreciable amounts of LC-2f, HC-IIa, and HC-IIb isoforms, and fast-twitch muscle isomyosin consisted of LC-2s and HC-I isoforms as well as fast-twitch LC and HC isoforms. Without consideration of HC- and slow-twitch alkali LC heterodimers, at least 31 possible isomyosins are derived from these findings on the subunit composition of isomyosins in human skeletal muscle.

Critical determinants of endurance performance in middle-aged and elderly endurance runners with heterogeneous training habits.

The current investigation was designed to determine which factor or what combination of factors would best account for distance running performance in middle-aged and elderly runners (mean age 57.5 years SD +/- 9.7) with heterogeneous training habits. Among 35 independent variables which were arbitrarily selected as possible prerequisites in the distance running performance of these runners, oxygen uptake (VO2) at lactate threshold (LT) (r = 0.781-0.889), maximal oxygen uptake (VO2 max) (r = 0.751 approximately 0.886), and chronological age (r = -0.736-(-)0.886) were found to be the 3 predictor variables showing the highest correlations with the mean running velocity at 5 km (V5km), 10 km (V10km), and marathon (VM). When all independent variables were used in a multiple regression analysis, any 3 or 4 variables selected from among VO2 at LT, chronological age, systolic blood pressure (SBP), atherogenic index (AI), and Katsura index (KI) were found to give the best explanation of V5km, V10km, or VM in a combined linear model. Linear multiple regression equations constructed for predicting the running performances were: V5km = 0.046X1-0.026X2-0.0056X3+5.17, V10km = 0.028X1-0.028X2-0.190X4-1.34X5+6.45, and VM = -0.0400X2-0.324X4-1.16X5+7.36, where X1 = VO2 at LT (ml.min-1.kg-1), X2 = chronological age, X3 = SBP, X4 = AI, and X5 = KI.(ABSTRACT TRUNCATED AT 250 WORDS)