Biomedical subjects

H Rusko

Publications and source records attributed to H Rusko.

At least 37 records · Page 2Linked to original sources

PubMed1996

Effects of sprint training on anaerobic performance characteristics determined by the MART.

The purpose of this study was to investigate the effects of sprint training on the anaerobic performance characteristics in well-trained sprint runners employing the maximal anaerobic running test (MART). Another purpose was to study the applicability of MART in the prescription of sprint training. Nine male sprint runners performed the MART before and after a 10-week intensive training period. The MART consisted of n.20-s runs on a treadmill with a 100-s recovery between the runs. Initial power, expressed as O2 demand (74 ml.kg-1.min-1), was increased by 6 ml.kg-1.min-1 for each consecutive run until exhaustion. Blood lactate concentration was measured at rest and after each run. Maximal power (Pmax), power at 10 mM (P10mM) and 3 mM (P3mM) blood lactate levels, and peak blood lactate concentration (peak BLa) were determined from the blood lactate vs O2 demand curve. The Pmax increased from 118.6 +/- 6.0 to 122.6 +/- 4.9 ml kg-1.min-1 (P = 0.009) during the training period and the changes of Pmax correlated positively with the volume of bounding exercises (r = 0.64; p = 0.032). The volume of extensive interval training correlated positively with the changes of P3mM (r = 0.62; p = 0.040) and negatively with the changes of P[10mM-3mM] (r = -0.68; p = 0.016) and peak BLa (r = -0.69; p = 0.019) during the particular training period. A positive correlation was also found between the changes of CMJrest and the volume of bounding and strength training (r = 0.60; p = 0.044). The present results suggested that sprint training induces an adaptive increase in the maximal anaerobic running power in well-trained male sprint runners. Furthermore, correlation analysis revealed that individual changes in P3mM, peak BLa, Pmax and CMJrest were related to the volume of specific training methods. Therefore we could conclude that the results of the MART could provide guidance in prescribing training for sprint running.

Adult↗

PubMed1996

Comparison of two maximal anaerobic cycling tests.

The purpose of this study was to compare two cycle ergometer modifications of the maximal anaerobic running test (MART) with each other and with the MART. Ten male physical education students performed the two maximal anaerobic cycling tests (MACT) in a random order and the MART between the MACTs. Each test consisted of n.20-s exercise bouts with a 100-s recovery period between them. Based on the ACSM equations the oxygen demand of the initial bout in each test equalled 56 ml.kg-1.min-1 and the increase for each consecutive bout was 6 ml.kg-1.min-1. In MACTres the resistance was increased and the pedalling frequency was kept constant (100 rpm) while in MACTfreq the frequency was increased and the resistance was constant (0.077 x body weight). In the MART the velocity of the treadmill was increased and the slope was constant (4 degrees). Blood lactate (BLa) concentration was measured at rest, 40 s after each run and during a 10-min recovery period. Maximal power (Pmax) was similar in the MART, MACTres and MACTfreq (107 +/- 4, 107 +/- 8 and 105 +/- 6 ml.kg-1.min-1, respectively) while significant differences (p < 0.05) were observed in the peak BLa (12.8 +/- 1.3, 15.6 +/- 1.7, and 14.7 +/- 2.1 mM, respectively). BLa was lower in the MACTfreq than in the MACTres until the oxygen demand of 86 ml.kg-1.min-1 and it was higher in both MACTs compared to the MART at each workload. We concluded that the MART can be modified for the bicycle ergometer although metabolic acidosis was greater in bicycle modifications. Further, the comparison of the MACTres and MACTfreq showed that blood lactate accumulation was greater at the higher pedalling frequency.

Acidosis↗

PubMed1995

Time course of anaerobic and aerobic energy expenditure during short-term exhaustive running in athletes.

The aim of the present study was to investigate the time course of aerobic and anaerobic energy yield during supramaximal exhaustive running on the treadmill in sprint and endurance athletes. In addition, the relationships between O2 deficit, excess post-exercise O2 consumption (EPOC) and peak post-exercise blood lactate concentration (peak BLa) values were examined, Oxygen uptake during the exhaustive run and 15 min recovery period was measured using a breath-by-breath method. The accumulated O2 deficit was calculated by an extrapolation procedure. Total running time was the same for eight male sprint runners (49.5 +/- 6.0s) and for six male endurance athletes (49.4 +/- 5.3 s). The sprint group had significantly higher O2 deficit (p < 0.01) during the run as well as higher peak BLa (p < 0.05) and EPOC (p < 0.01) after the run than the endurance group. The relative contribution of anaerobic energy yield decreased from 80% to 60% during the first 15 s of the exhaustive run in both groups. The VO2 peaked and was almost unchanged from 25th to 40th s of the run in both groups, although only 79% of their VO2max was attained. The relative contribution of aerobic energy yield was significantly higher (p < 0.05) in the endurance (54-63%) than in the sprint group (43-47%) during the second half of the run. No correlation was found between the O2 deficit and EPOC but peak BLa correlated significantly (p < 0.05) with the O2 deficit (r = 0.53) and EPOC (r = 0.53). In conclusion, the energy release of the sprint and endurance athletes was different only during the second half of the exhaustive supramaximal run, when the sprinters used more the anaerobic and endurance athletes aerobic pathways for energy production.

Adult↗

PubMed1995

Cooling-induced changes in muscular performance and EMG activity of agonist and antagonist muscles.

The effect of whole body cooling on the muscular performance and electromyographic (EMG) activity of agonist and antagonist muscles during dynamic exercise was studied. Eleven slightly clothed male subjects were exposed to ambient temperatures of 27 degrees C and 10 degrees C for 60 min. After the exposures the subjects performed an overhead ball throwing test. Five balls, weighing from 0.3 kg to 3.0 kg were thrown and the velocity of the balls was measured. The EMG activity of two agonist-antagonist muscle pairs (m. triceps brachii--m. deltoideus and m. rectus abdominis--m. erector spinae) were measured during throwing. Cooling decreased mean skin temperature by 6.3 +/- 0.5 degree C (mean +/- SE). The temperature of m. triceps brachii decreased by 4.0 +/- 1.6 degrees C and 1.8 +/- 0.6 degrees C from the depth of 20 and 30 mm underneath the skin surface, respectively. The corresponding values of m. deltoideus were 5.1 +/- 0.4 degrees C and 3.2 +/- 0.8 degrees C. The cooling-induced decrement in ball velocity varied from 9.4 +/- 3.3% (0.3-kg ball) to 5.6 +/- 2.8% (3.0-kg ball) (p < 0.001-0.01). After cooling, the time to reach the maximal level of integrated electromyographic (IEMG) activity in m. triceps brachii (agonist) was increased (30-42%, p < 0.05-0.001). Moreover, cooling decreased the mean IEMG activity m. triceps brachii, while the activity of m. deltoideus (antagonist) was increased. The alteration was significant (p < 0.05-0.001) with the three lightest balls.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1994

Neuromuscular characteristics and fatigue in endurance and sprint athletes during a new anaerobic power test.

The purpose of this study was to investigate neuromuscular and energy performance characteristics of anaerobic power and capacity and the development of fatigue. Ten endurance and ten sprint athletes performed a new maximal anaerobic running power test (MARP), which consisted of n x 20-s runs on a treadmill with 100-s recovery between the runs. Blood lactate concentration [la-]b was measured after each run to determine submaximal and maximal indices of anaerobic power (P3 mmol.l-1, P5 mmol.l-1, P10 mmol.l-1 and Pmax) which was expressed as the oxygen demand of the runs according to the American College of Sports Medicine equation: the oxygen uptake (ml.kg-1.min-1) = 0.2 x velocity (m.min-1) + 0.9 x slope of treadmill (frac) x velocity (m.min-1) + 3.5. The height of rise of the centre of gravity of the counter movement jumps before (CMJrest) and during (CMJ) the MARP test, as well as the time of force production (tF) and electromyographic (EMG) activity of the leg muscles of CMJ performed after each run were used to describe the neuromuscular performance characteristics. The maximal oxygen uptake (VO2max), anaerobic and aerobic thresholds were determined in the VO2max test, which consisted of n x 3-min runs on the treadmill.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1994

EMG activities and ground reaction forces during fatigued and nonfatigued sprinting.

The present study was designed to investigate EMG activities and ground reaction forces during fatigued and nonfatigued running. Ten male sprint runners volunteered to run a maximal 20-m speed test, a 400-m time trial, and submaximal 20-m runs at the average speed of the first 100 m of the 400 m. During the latter stage of each run, ground reaction forces and EMG activity of four leg muscles were recorded. EMG activities were time averaged during three phases of running: preactivation, braking, and propulsion phase. The resultant ground reaction forces both in the braking (P < 0.001) and in the propulsion phase (P < 0.01) were greater in the maximal and submaximal 20 m than at the end of the 400 m. The averaged EMG during the braking phase (P < 0.01) and during the total ground phase (P < 0.05) was smaller in the submaximal 20 m than at the end of the 400 m. On the other hand the averaged EMG was greater during the maximal 20 m than at the end of the 400 m during the propulsion phase (P < 0.001) and during the total ground phase (P < 0.05). In addition, the more the preactivity increased the less the resultant ground reaction force decreased in the braking phase during the 400 m run (r = 0.77, P < 0.05). It was concluded that the role of the increased neural activation was to compensate for muscular fatigue and the preactivation had an important role in maintaining force production during the 400-m run. In addition, the fatigue was different in each working muscle.

Adult↗

PubMed1994

Perceived exertion during submaximal G exposures before and after physical training.

Ratings of perceived exertion (RPE) were registered at submaximal levels in G endurance tests of a combined strength and endurance training program in 17 pilots. After 12 months of physical training, the endurance G tolerance (time to exhaustion during simulated aerial combat maneuver), increased by a mean of 40% (p < 0.001), while the mean RPE at 5 min submaximal G exposure decreased by 1.2 units (p < 0.02). Following 12 months of physical training, a significant relationship was observed between the improvement of the endurance G tolerance and the decrease of the RPE at 5 min (p = 0.05). Mean SaO2 at 5 min increased from 84 to 90% (p < 0.01) after training, while heart rate responses to G stress did not change. It is concluded that mean RPE and, to some extent, mean SaO2 during submaximal G exposures may be used as indicators of shifts in endurance G tolerance. The procedure may reduce the need for exhaustive G tolerance tests with associated risks and discomfort.

Aerospace Medicine↗

PubMed1993

The effect of ski training at altitude and racing on pituitary, adrenal and testicular function in men.

The effect of similar prolonged exercise on hormonal changes was studied at sea level and at moderate altitude. Four cross-country skiers participated in a 30-km race and five biathlonists in a 20-km race at sea level in Finland and during altitude training and racing at 1650 m in Les Saisies, France. Venous blood samples were taken at both altitudes before the race between 0800 and 0900 hours and 25-35 min after the race. Resting blood samples were also taken before and after the altitude training and the period of racing. Serum testosterone concentration was higher before the race at altitude than at sea level (19%, P < 0.02), and 30 min after the race growth hormone (GH) concentration was higher at sea level than at moderate altitude (P < 0.002). There were not significant differences in serum luteinising hormone between the altitudes. Serum cortisol concentration was higher after the altitude training and the period of racing than before (P < 0.02) but no difference was observed in testosterone. We concluded, that since the profiles of the anabolic-catabolic hormone concentrations measured are indicators of the performance level of athletes, our data indicated that to follow them during altitude training could be beneficial in optimizing training programme for individual athletes. We also concluded, that the lower GH concentration after racing at moderate altitude may have been a consequence of decreased racing speed and/or increased physical performance.

Adrenal Glands↗

PubMed1993

A new method for the evaluation of anaerobic running power in athletes.

A new maximal anaerobic running power (MARP) test was developed. It consisted of n.20-s runs on a treadmill with a 100-s recovery between the runs. During the first run the treadmill speed was 3.97 m.s-1 and the gradient 5 degrees. The speed of the treadmill was increased by 0.35 m.s-1 for each consecutive run until exhaustion. The height of counter-movement jumps and blood lactate concentration ([la-]b) were measured after each run. Submaximal ([la-]b = 3 mmol.l-1 and 10 mmol.l-1) and maximal speed and power (W3mmol, W10mmol and Wmax, respectively) were calculated and W was expressed in oxygen equivalents according to the American College of Sports Medicine equation. Thirteen male athletes whose times over 400 m ranged from 47.98 s to 54.70 s served as subjects. In the MARP-test the speed at exhaustion was 6.89 (SD 0.28) m.s-1 corresponding to a Wmax of 118 (SD 5) ml.kg-1 x min-1. The peak [la-]b after exhaustion was 17.0 (SD 1.6) mmol.l-1. A significant correlation (r = 0.89, P < 0.001) was observed between the Wmax and the average speed in the 400-m sprint. The maximal 20-m sprinting speed on a track and W10mmol correlated with both the Wmax and the 400-m speed. It was concluded that the new method allows the evaluation of several determinants of maximal anaerobic performance including changes in the force-generating capacity of leg muscles and [la-]b relative to the speed of the sprint running. the [la-]b at submaximal sprinting speed was suggested as describing the anaerobic sprinting economy.

Adult↗

PubMed1993

Interrelations between power, force production and energy metabolism in maximal leg work using a modified rowing ergometer.

The dependence of power on aerobic and anaerobic energy metabolism and on force production was studied in maximal leg exercise. National and international level male rowers (n = 9) performed four modified (legs-only) rowing ergometer exercises: a progressive test, 2-min (T2), 12-min (T12) and 6-min (T6) all-out tests. In T2, significant correlations were observed between power in T2 (PT2) and oxygen debt (r = 0.83, P < 0.05) and between PT2 and average force production (Fav) during the last 30 s (r = 0.85, P < 0.05). These parameters explained 93% of the variation in PT2. The highest correlations between power in T6 (PT6) and physiological parameters were as follows: maximal oxygen uptake (VO2 max: r = 0.87, P < 0.01), blood bicarbonate concentration before the test ([HCO3-before]: r = 0.85, P < 0.05) and blood lactate concentration on anaerobic threshold (BLaAnT: r = -0.82, P < 0.05). Together, these parameters explained 92% of the variation in PT6. In T12, the total power (PT12) correlated with power of anaerobic threshold (PAnT: r = 0.95, P < 0.001) and with the highest VO2 value in this test (VO2 peak: r = 0.92, P < 0.001). These two parameters explained 96% of the variation in PT12. The decrease of at least one of the force parameters during each test was taken as a sign of fatigue. The decline in force was compensated for by an increase in stroke rate at the end of T6 and T12 (P < 0.01, P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1993

Aerobic characteristics, oxygen debt and blood lactate in speed endurance athletes during training.

Aerobic characteristics, oxygen debt and blood lactate were analysed in 20 male speed endurance athletes (400 m sprinters and 400 m hurdlers). The subjects were tested three times; at the beginning of March, at the end of May and at the end of August. Aerobic and anaerobic threshold and maximal oxygen uptake measured on the treadmill decreased (p < 0.05-0.01) from the second test occasion to the third one. The anaerobic work test on the treadmill was a constant load test at 5.56 m.s-1 with a slope of 4 degrees. The time to exhaustion increased (p < 0.05) from the first test occasion (112 +/- 17 s) to the second one (136 +/- 35 s) and did not change in the last test (135 +/- 25 s). Following the anaerobic work test oxygen debt was measured during 20 minutes. The highest total oxygen debt values (144 +/- 19 ml.kg-1) were observed in the second test occasion. Peak blood lactate following the anaerobic work increased (p < 0.05) from the first test occasion to the second one and remained at the same level during the next three competitive months. The good speed endurance athletes differed from the poor counterparts in time to exhaustion (p < 0.01), in 100 m record time (p < 0.01) and in maximal oxygen uptake (p < 0.05). Our results suggest that aerobic characteristics decrease during the competitive period in speed endurance athletes. The anaerobic performance capacity including work time and peak blood lactate is at high level in the competitive period.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

Changes in force production, blood lactate and EMG activity in the 400-m sprint.

The neural activation (iEMG) and selected stride characteristics of six male sprinters were studied for 100-, 200-, 300- and 400-m experimental sprints, which were run according to the velocity in the 400 m. Blood lactate (BLa) was analysed and drop jumps were performed with EMG registration at rest and after each sprint. Running velocity (P less than 0.001) and stride length (P less than 0.05) decreased and contact time increased (P less than 0.01) during the 400-m sprint. The increase in contact time was greatest immediately after runs of 100 and 300 m. The peak BLa increased and the rate of BLa accumulation decreased with running distance (P less than 0.001). The height of rise of the centre of mass in the drop jumps was smaller immediately after the 300 m (P less than 0.05) and the 400 m (P less than 0.01) than at rest, and it correlated negatively with peak BLa (r = -0.77, P less than 0.001). The EMG and EMG:running velocity ratio increased with running distance. It was concluded that force generation of the leg muscles had already begun to decrease during the first quarter of the 400-m sprint. The deteriorating force production was compensated for until about 200-300 m. Thereafter, it was impossible to compensate for fatigue and the speed of running dropped. According to this study, fatigue in the 400-m sprint among trained athletes is mainly due to processes within skeletal muscle rather than the central nervous system.

Adult↗

PubMed1992

Does anaerobic threshold correlate with maximal lactate steady-state?

The aim of this study was to compare the 'anaerobic threshold' (AnT) of subjects determined during a continuous 2-min incremental exercise test until exhaustion and the 'maximal lactate steady-state' (BLaSsmax) determined during prolonged exercise at constant loads corresponding to the subjects' AnT and/or 5-25% above and below it. Seventeen subjects performed an incremental exercise test and 1-5 prolonged exercise tests on a cycle ergometer until exhaustion at intervals of 1 week, and work rates, oxygen uptake (VO2) values and brachial venous blood lactate (BLa) levels were measured. It was proposed that when exercising at a constant workload below AnT, BLa would fall after having reached its peak; at the level of AnT, BLa reaches maximal steady-state (BLaSsmax); and above AnT, BLa increases continuously. Altogether, in 34 of 45 tests with a constant workload between 80 and 125% AnT, BLa values were as expected. In those cases in which BLaSsmax was reached, BLa increased on average by 3.8 mM from resting levels. This increase was 2.0 mM greater than that seen between resting levels and AnT during incremental exercise. There was no correlation between BLa values at BLaSsmax and at AnT, both when expressed as an increase in BLa (delta BLa) and absolute BLa concentration. Altogether, 81% of the variation in BLa concentration at BLaSsmax could be explained by the subjects' age, the percentage of slow-twitch fibres and BLa levels at rest. The AnT and BLaSsmax did not differ significantly, and these values were correlated (r = 0.83). Together, AnT and age accounted for 85% of the variation seen in BLaSsmax. The BLaSsmax did not correlate with AnT when fixed at a BLa concentration of 4 mM (AnT4mM). The three hypotheses tested in this study were confirmed, and the present results demonstrate that AnT correlates with BLaSsmax. The few exceptions to anticipated BLa kinetics were small in magnitude and could be explained by physiological variations.

Adenosine Triphosphatases↗

PubMed1992

Fatigue and changes of ATP, creatine phosphate, and lactate during the 400-m sprint.

Fatigue during the 400-m sprint was studied by measuring muscle ATP, creatine phosphate (CP), lactate (M-La), and blood lactate (B-La) in six male runners before and after four experimental sprints (100, 200, 300, and 400 m). During the first 100 m, muscle CP decreased from 15.8 +/- 1.7 to 8.3 +/- 0.3 mmol/kg while M-La increased to 3.6 +/- 0.4 mmol/kg. After 200 m the CP had decreased to 6.5 +/- 0.5 mmol/kg and M-La had increased to 8.3 +/- 1.1 mmol/kg. At the end of the 400 meters, ATP and CP concentrations had decreased by 27% and 89%, respectively, and M-La had increased to 17.3 +/- 0.9 mmol/kg. It was concluded that after 200 m the speed of running decreased, although CP was not depleted and lactate concentration was not at maximum level. Complete fatigue occurred when CP stores were depleted and B-La and M-La attained an individual maximum.

Adenosine Triphosphate↗

PubMed1991

Effects of explosive type strength training on physical performance characteristics in cross-country skiers.

To investigate the effects of a combination of simultaneous strength and endurance training on selected neuromuscular and aerobic performance characteristics seven male cross-country skiers underwent training for a period of 6 weeks. The experimental group trained 6-9 times per week with a programme consisting of 34% explosive type strength training and 66% endurance training during the first 3 weeks of the experiment and 42% and 58% respectively during the last 3 weeks of the experiment. The total volume of training of the control group (eight skiers) was of the same magnitude but consisted of 85% pure endurance training and 15% endurance type strength training. The experimental training regime resulted in specific changes in neuromuscular performance. This was demonstrated by improvements (P less than 0.01) in the maximal heights of rise of the centre of gravity in the squat and countermovement jumps. A significant decrease (P less than 0.05) took place also in the time of rapid isometric force production during experimental training, while no changes occurred in the maximal force of the trained muscles. Aerobic performance characteristics of the experimental group did not change during the experimental training period. No significant changes occurred in neuromuscular or aerobic performance characteristics in the control group. These findings indicated that training-induced improvements in explosive force production may not be fully inhibited by this kind of aerobic training. They also suggested that endurance athletes could undertake explosive type strength training programmes without a concomitant reduction in aerobic capacity, if the overall loading of training were within predefined limits.

Adult↗

PubMed1991

Muscle enzyme adaptations to added load during training and nontraining hours in rats.

The effects of added load (20% of body mass) on the selected enzyme activities of red and white quadriceps femoris (QF), soleus, and gastrocnemius muscles of rats were studied. The rats were divided into sedentary control (SC), sedentary control with added load (SC+AL), endurance training (ET), and endurance training with added load (ET+AL) groups (n = 10 rats/group). After 6 wk, the SC+AL group had 57% higher (P less than 0.001) beta-glucuronidase (beta-GU) activity and 24% lower (P less than 0.05) citrate synthase activity in white QF than SC. Citrate synthase activity was also decreased in red QF (P less than 0.05) after the added load was used during nontraining hours. The training with added load induced similar but more pronounced changes than normal endurance training, especially in white QF. The ET+AL group demonstrated higher citrate synthase activity in white QF (P less than 0.001) and gastrocnemius (P less than 0.01) and higher malate dehydrogenase activity (P less than 0.05) and beta-GU activity (P less than 0.001) in white QF than the ET group. ET+AL rats also had higher phosphofructokinase (P less than 0.01) and lower creatine kinase (P less than 0.001) activity in white QF than ET rats. In conclusion, the added load without training had minor adaptive influences on muscles. The added load during training hours seemed to be an effective means of influencing the activation and adaptation in muscles that contain fast glycolytic fibers.

Adaptation, Physiological↗

PubMed1990

The relation between cycling time to exhaustion and anaerobic threshold.

This study investigated whether the anaerobic threshold (AnT) could be used to predict prolonged work capacity measured as cycling time to exhaustion (= endurance time) and which factors, in addition to relative exercise intensity, could explain variation in endurance time. Theoretical exercise intensities corresponding to certain endurance times were also calculated. The hyperbolic and exponential functions between cycling time and relative work rate (WR[%]), as well as between cycling time and relative oxygen uptake (VO2[%]) were fitted to the pooled data (n = 45) of 17 subjects. The WR(%) and VO2(%) were expressed as a percentage of the subject's own AnT- and maximum-values. At WR corresponding to AnT (i.e., 70% of WRmax) an average subject could cycle 60 min according to both AnT- or maximum-related exponential function. When prediction was done for an endurance time of 4 h, the AnT-related exponential function gave 2.9%-units (= 11 W or approximately 0.15 O2 l.min-1) lower intensity level (51% of WRmax) than the maximum-related function (54% of WRmax). The WR(%) alone explained 54% and 70% of the variation in endurance time of the AnT-related and maximum-related exponential functions, respectively. Muscle fibre composition and initial blood lactate or relative muscle glycogen depletion (change in muscle glycogen as percentage) increased significantly the explanatory power of these models. The differences between the observed and expected exercise times correlated with blood lactate accumulation (r = -0.42; p less than 0.01), muscle fibre composition (r = 0.33; p less than 0.05) and relative muscle glycogen depletion (r = 0.67; p less than 0.01). It was concluded that the capacity for prolonged work measured as cycling time to exhaustion can be estimated by AnT-related power output, and that the exponential function model is the most suitable. Prediction power of the model can be improved by multiple regressions including muscle fibre composition, initial blood lactate level and relative muscle glycogen depletion.

Adult↗

PubMed1990

Mechanical work and efficiency in treadmill running at aerobic and anaerobic thresholds.

Mechanical work, mechanical power, energy consumption and mechanical efficiency were studied in constant-speed treadmill running of 5 min at seven different exercises around aerobic (AerT) and anaerobic (AnT) thresholds. The true efficiency of concentric (positive) mechanical work and gross efficiency of the whole body in seven male subjects were calculated. The total mechanical work was calculated from film through the translational, potential and rotational energy states as the sum of the changes of all the mechanical energy states in all body segments allowing energy transfer between segments and from energy state to state. The total energy consumption was measured by combining aerobic and anaerobic energy production in resting and working conditions. When the speed of the treadmill was increased from the velocity of 10 km h-1 (2.8 m s-1) to 22 km h-1 (6.1 m s-1), the concentric mechanical work per one step increased from 129 +/- 45 J to 228 +/- 82 J (P less than 0.01). Oxygen consumption increased from 2.22 +/- 0.27 1 min-1 to 4.47 +/- 0.24 1 min-1. The amount of blood lactate increased from 0.94 +/- 0.53 mmol l-1 at the lowest speed to 9.90 +/- 2.89 mmol l-1 at the highest speed (P less than 0.001). The true efficiency of concentric work decreased from 74 +/- 14% to 56 +/- 8% (P less than 0.05). At the speed of the AerT, the economy of running, the vertical rise of different body segments and mechanical efficiency of positive work were high. The highest gross efficiency was found at the running speed between the AerT and AnT.

Adolescent↗