Energy system contribution during 200- to 1500-m running in highly trained athletes

PURPOSE: The purpose of the present study was to profile the aerobic and anaerobic energy system contribution during high-speed treadmill exercise that simulated 200-, 400-, 800-, and 1500-m track running events. METHODS: Twenty highly trained athletes (Australian National Standard) participated in the study, specializing in either the 200-m (N = 3), 400-m (N = 6), 800-m (N = 5), or 1500-m (N = 6) event (mean VO2 peak [mL x kg(-1)-min(-1)] +/- SD = 56+/-2, 59+/-1, 67+/-1, and 72+/-2, respectively). The relative aerobic and anaerobic energy system contribution was calculated using the accumulated oxygen deficit (AOD) method. RESULTS: The relative contribution of the aerobic energy system to the 200-, 400-, 800-, and 1500-m events was 29+/-4, 43+/-1, 66+/-2, and 84+/-1%+/-SD, respectively. The size of the AOD increased with event duration during the 200-, 400-, and 800-m events (30.4+/-2.3, 41.3+/-1.0, and 48.1+/-4.5 mL x kg(-1), respectively), but no further increase was seen in the 1500-m event (47.1+/-3.8 mL x kg(-1)). The crossover to predominantly aerobic energy system supply occurred between 15 and 30 s for the 400-, 800-, and 1500-m events. CONCLUSIONS: These results suggest that the relative contribution of the aerobic energy system during track running events is considerable and greater than traditionally thought.     

Comparison of the VO2 response to 800-m, 1500-m and 3000-m track running events

AIM: The present study examined the VO2 response to middle-distance track running events of 800 m, 1500 m and 3000 m and investigated the relationship between the speed of the VO2 response ((1) and subsequent race performance. METHODS: Trained 3000-m (n = 8), 1500-m (n = 10) and 800-m (n = 8) male track athletes performed a laboratory GXT plus a run at 14 km x h(-1) and multiple race time trials. For each subject, a bi-exponential model fit from 20 s was used to categorise the O2 response for the best performed track run and also the treadmill run at 14 km x h(-1). RESULTS: Faster (1 values were noted the shorter the track event, with values of 14, 18.5 and 20.8 s for 800-, 1500- and 3000-m events, respectively. ANOVA results revealed that differences in (1 were significant (P < 0.05) for the 800- and 3000-m, but not for the 800- and 1500-m (P = 0.06) or 1500- and 3000-m events (P = 0.15). Only 1500-m race performance was significantly correlated to race (1 (r = 0.71). Values for (1 at an absolute velocity treadmill run (14 km x h(-1)) did not differ significantly between different events and were not correlated to race performance for any event. From pooled data for all three events, significant correlations (P < 0.01) were noted between tau1 and the speed over the first 800-m (r = -0.54 to -0.68). CONCLUSIONS: There was a trend for faster (1values the shorter the track event. The significant correlation between tau1 and initial starting velocity suggests this may be attributed to the faster starting velocity of the shorter track events, rather than any differences between athletes per se.     

Differences in lactate exchange and removal abilities in athletes specialised in different track running events (100 to 1500 m)

The purpose of this study was to investigate whether track running specialisation could be associated with differences in the ability to exchange and remove lactate. Thirty-four male high-level runners were divided into two groups according to their specialty (100 - 400 m/800 - 1500 m). All performed a 1-min 25.2 km x h -1 event, followed by a 90-min passive recovery to obtain individual blood lactate recovery curves which were fitted to a bi-exponential time function: [La](t) = [La](0) + A 1 (1-e -gamma1t) + A 2 (1-e -gamma2t). The velocity constant gamma 1 which denotes the ability to exchange lactate between the previously worked muscles and blood was higher (p < 0.001) in middle-distance runners than in sprint runners. The velocity constant gamma 2 which reflects the overall ability to remove lactate did not differ significantly between the two groups. gamma 1 was positively correlated with the best performance over 800 m achieved by 16 athletes during the outdoor track season following the protocol (r = 0.55, p < 0.05). In conclusion, the lactate exchange ability seems to play a role on the athlete's capacity to sustain exercise close to 2-min-duration and specifically to run 800 m.     

Oxygen uptake response to an 800-m running race

We tested the hypothesis that time course of O (2) uptake (VO (2)) measured during a supramaximal exercise performed in the field is driven to maximal oxygen uptake (VO (2max)). On an outdoor track, five middle-distance male runners first performed a test to determine VO (2max) and a supramaximal 800-m running test at least two days apart. VO (2) response was measured from the start to the end of exercise with the use of a miniaturised telemetric gas exchange system (Cosmed K4). VO (2max) was reached by all subjects 45 +/- 11 s (mean +/- SD) after the onset of the 800-m race (i.e., 316 +/- 75 m), and was maintained during the next 33 +/- 6 s (i.e., 219 +/- 41 m). The mean relative exercise intensity of the 800 m was 120 % VO (2max). An unexpected significant decrease in VO (2) (24.1 +/- 7.0 %; p < 0.05) was observed in all subjects during the final 38 +/- 17 s (i.e., the last 265 +/- 104 m). We concluded that, at onset of a simulated 800 m running event, VO (2) is quickly projected towards the VO (2max), and then becomes limited by the achievable VO (2max). This race profile shown by all athletes is in some contrast to what can be expected from earlier findings in a laboratory setting.     

Determinants of 800-m and 1500-m running performance using allometric models

PURPOSE: To identify the optimal aerobic determinants of elite, middle-distance running (MDR) performance, using proportional allometric models. METHODS: Sixty-two national and international male and female 800-m and 1500-m runners undertook an incremental exercise test to volitional exhaustion. Mean submaximal running economy (ECON), speed at lactate threshold (speedLT), maximum oxygen uptake (.VO(2max)), and speed associated with .VO(2max) (speed.VO(2max)) were paired with best performance times recorded within 30 d. The data were analyzed using a proportional power-function ANCOVA model. RESULTS: The analysis identified significant differences in running speeds with main effects for sex and distance, with .VO(2max) and ECON as the covariate predictors (P < 0.0001). The results suggest a proportional curvilinear association between running speed and the ratio (.VO(2max).ECON(-0.71))(0.35) explaining 95.9% of the variance in performance. The model was cross-validated with a further group of highly trained MDR, demonstrating strong agreement (95% limits, 0.05 +/- 0.29 m.s(-1)) between predicted and actual performance speeds (R(2) = 93.6%). The model indicates that for a male 1500-m runner with a .VO(2max) of 3.81 L.min(-1) and ECON of 15 L.km(-1) to improve from 250 to 240 s, it would require a change in .VO(2max) from 3.81 to 4.28 L.min(-1), an increase of Delta0.47 L.min(-1). However, improving by the same margin of 10 s from 225 to 215 s would require a much greater increase in .VO(2max), from 5.14 to 5.85 L.min(-1), an increase of Delta0.71 L.min(-1) (where ECON remains constant). CONCLUSION: A proportional curvilinear ratio of .VO(2max) divided by ECON explains 95.9% of the variance in MDR performance.     

Linear kinematics of the men's 110-m and women's 100-m hurdles races.

Twenty-three male and nine female hurdlers were filmed using three-dimensional methods during competition at the 1988 United States Olympic Trials. An entire four-step cycle was analyzed, including the clearances of the men's fifth hurdle and the women's fourth hurdle. The results showed an increase in vertical velocity and a decrease in forward horizontal velocity during the takeoff of the hurdle step. The forward velocity was recovered mainly in the second support phase after the hurdle. The downward motion of the center of mass (c.m.) was not stopped until the second support phase after the hurdle clearance. The peak of the c.m. parabola was almost directly over the hurdle in the men, and 0.30 m before the hurdle in the women. It was shown that the women used a parabola with a larger margin over the top of the hurdle than the men: A lower parabola would shorten the hurdle step, and would require the lengthening of the three interhurdle steps. It would also make the duration of the airborne phase too short, which would not give the legs enough time to prepare for landing after the execution of their motions over the hurdle. Therefore, women should not be coached to imitate the men's hurdle clearance technique.     

Angular momentum in the men's 110-m and women's 100-m hurdles races.

Twenty-three male and nine female hurdlers were filmed using three-dimensional methods at the 1988 United States Olympic Trials. With respect to the athletes, the X, Y, and Z axes pointed to the right, forward, and upward, respectively. During hurdle clearance, the X component of angular momentum was negative (clockwise rotation in a view from the right). Early in the airborne phase, it was associated with the motion of the trail leg. The downward motion of the lead leg was produced mainly by transfer of angular momentum from the trail leg, rather than by the lifting of the head-trunk. The Y component of angular momentum was negative (counterclockwise in a back view of a hurdler taking off from the right foot). It was necessary for the abduction of the trail leg. When this abduction slowed down, the angular momentum was taken up by the lowering (and slight adduction) of the left leg and elevation of the right elbow. The hurdle clearance required a positive Z component of angular momentum (counterclockwise in an overhead view): The clockwise angular momentum of the right arm as it swept backward was not enough to compensate for the larger counterclockwise angular momentum required for the forward motion of the trail leg. Our improved understanding of the rotations involved in hurdling will be useful for the correction of technique defects in individual athletes.     

The relative contributions of anaerobic and aerobic energy supply during track 100-, 400- and 800-m performance

AIM: The present study set out to identify the relative contribution of the laboratory determined physiological measures, (maximal) accumulated oxygen deficit (AOD) and maximal oxygen uptake (VO(2max)), when predicting track performance. METHODS: Fourteen volunteers (men: n=10; women: n=4); mean (+/- standard deviation [SD]) height 1.76+/-0.1 (men) vs 1.62+/-0.08 m (women); body mass: 67.9+/-7.1 (men) vs 50.6+/-8.2 kg (women), ran track races at distances of 100, 400 and 800 m. The individually determined (maximal) AOD and VO(2max) were measured under controlled laboratory conditions (68.3+/-10.2 vs 60.7+/-16.1; men vs women, mL x (2) x Eq x kg(-1)) and (68.7+/-7.3 vs 55.6+/-4.3; men vs women, mL x kg(-1) x min(-1)), respectively. RESULTS: Track performance could be predicted using both laboratory measures, AOD and , with a high degree of accuracy: R2=76.9%, 84.8% and 89.1% for 100, 400 and 800 m, respectively. Data analysis confirmed the dominant energy supply during 100-m sprinting was the anaerobic energy supply processes, reflected as AOD. In contrast, oxidative metabolism (reflected as VO(2max)) was the dominant source of energy supply during 800-m performance. CONCLUSION: The results support earlier research, rather than present textbook dogma, namely that aerobic and anaerobic processes contribute equally to maximal exercise lasting approximately 60 s.     

Power and metabolic responses during supramaximal exercise in 100-m and 800-m runners

The differences in ergometric power and in biochemical characteristics of the vastus lateralis muscle (VL) between 100-m and 800-m runners (R) were studied in 2 groups of 8 male athletes (100m-R and 800m-R) during a 45-s all-out cycle ergometer exercise. Peak power (PP), mean power (MP) and percentage of fatigue were respectively 24%, 13% and 24% higher in the 100m-R than in 800m-R, whereas total work output was similar in both groups. In 100m-R, there was a higher percentage of fast twitch (FT) fibres, a higher buffer (mß) titration capacity and a lower oxidative potential expressed by citrate synthase, 3-hydroxyacyi-CoA dehydrogenase and cytochrome oxidase than in 800m-R. During all-out exercise, muscle lactate [lact] and protons [H+] accumulated significantly more in 100m-R than in 800m-R with a corresponding muscle pH of 6.49 ± 0.07 and 6.63 ± 0.12. However, the decreases in adenosine triphosphate (ATP) and creatine phosphate were not different between the two groups. Significant correlations were found between PP (or % fatigue) and Δ[H+], Δ[lact], Δ[ATP], %FT or oxidative capacity when the two groups were pooled together. It was concluded mat the difference in %FT, in titration mß and in the contribution of the glycolytic and oxidative processes observed in VL between 100m-R (pure anaerobic training) and 800m-R (mixed aerobic-anaerobic training) are determinant factors in the pattern of energy output during supramaximal exercise.     

Heart rate overshoot in running events.

The phenomenon of heart rate overshoot has been examined in 6 high-school athletes aged 15-16 years and in 8 university athletes aged 19-20 years. The incidence was 100% over distances of 50, 100 and 200 metres, and only one subject failed to show an overshoot following a 400 metre run. However, the overshoot was relatively larger and more long-lived following the shorter runs. While an accumulation of anaerobic metabolites seems the most likely explanation of the phenomenon over the longer distances, in the 50 metre event the Valsalva manoeuvre may also make some contribution.     

Aerobic requirements and maximum aerobic power in treadmill and track running.

Treadmill and track running comparisons were made on eight track athletes. Oxygen uptake (VO2) during steady-state and maximum aerobic power (VO2 max) were measured in a discrete series of three speeds, and at maximal effort. Running speeds were always in sequence from slowest to fastest. Expired air was collected from the runner by the Douglas-bag method, and analyzed by the Lloyd-Haldane technique. Neither VO2 max nor aerobic requirements of running were significantly different in track and treadmill determinations. There were several correlations: 1) VO2 max with body weight (r = .83 P less than .02), 2) treadmill and track determinations of VO2 max (r = .95, P less than .01) and 3) VO2 ml/kg with running velocity m/min (r = .91, P less than .01) where the regression was linear and may be represented by the equation Y = 5.36 + 0.172X, where Syx = 2.7 m102/kg. It is concluded that treadmill determinations of oxygen uptake may be validly applied to track running in calm air within the range of 180...260 m/min.     

Energy system interaction and relative contribution during maximal exercise

There are 3 distinct yet closely integrated processes that operate together to satisfy the energy requirements of muscle. The anaerobic energy system is divided into alactic and lactic components, referring to the processes involved in the splitting of the stored phosphagens, ATP and phosphocreatine (PCr), and the nonaerobic breakdown of carbohydrate to lactic acid through glycolysis. The aerobic energy system refers to the combustion of carbohydrates and fats in the presence of oxygen. The anaerobic pathways are capable of regenerating ATP at high rates yet are limited by the amount of energy that can be released in a single bout of intense exercise. In contrast, the aerobic system has an enormous capacity yet is somewhat hampered in its ability to delivery energy quickly. The focus of this review is on the interaction and relative contribution of the energy systems during single bouts of maximal exercise. A particular emphasis has been placed on the role of the aerobic energy system during high intensity exercise. Attempts to depict the interaction and relative contribution of the energy systems during maximal exercise first appeared in the 1960s and 1970s. While insightful at the time, these representations were based on calculations of anaerobic energy release that now appear questionable. Given repeated reproduction over the years, these early attempts have lead to 2 common misconceptions in the exercise science and coaching professions. First, that the energy systems respond to the demands of intense exercise in an almost sequential manner, and secondly, that the aerobic system responds slowly to these energy demands, thereby playing little role in determining performance over short durations. More recent research suggests that energy is derived from each of the energy-producing pathways during almost all exercise activities. The duration of maximal exercise at which equal contributions are derived from the anaerobic and aerobic energy systems appears to occur between 1 to 2 minutes and most probably around 75 seconds, a time that is considerably earlier than has traditionally been suggested.     

Effect of caffeinated coffee on running speed, respiratory factors, blood lactate and perceived exertion during 1500-m treadmill running.

Using a motorized treadmill the study investigated the effects of the ingestion of 3 g of caffeinated coffee on: the time taken to run 1500 m; the selected speed with which athletes completed a 1-min 'finishing burst' at the end of a high-intensity run; and respiratory factors, perceived exertion and blood lactate levels during a high intensity 1500-m run. In all testing protocols decaffeinated coffee (3 g) was used as a placebo and a double-blind experimental design was used throughout. The participants in the study were middle distance athletes of club, county and national standard. The results showed that ingestion of caffeinated coffee: decreases the time taken to run 1500 m (P less than 0.005); increases the speed of the 'finishing burst' (P less than 0.005); and increases VO2 during the high-intensity 1500-m run (P less than 0.025). The study concluded that under these laboratory conditions, the ingestion of caffeinated coffee could enhance the performance of sustained high-intensity exercise.     

Flexibility and running economy in female collegiate track athletes

AIM: Limited information exists regarding the association between flexibility and running economy in female athletes. This study examined relationships between lower limb and trunk flexibility and running economy in 17 female collegiate track athletes (20.12+/-1.80 y). METHODS: Correlational design, subjects completed 4 testing sessions over a 2-week period. The 1st session assessed maximal oxygen uptake (VO2max=55.39+/-6.96 ml.kg-1.min-1). The 2nd session assessed trunk and lower limb flexibility. Two sets of 6 trunk and lower limb flexibility measures were performed after a 10-min treadmill warm-up at 2.68 m.s-1. The 3rd session consisted of 3 10-min accommodation runs at a speed of 2.68 m.s-1 which was approximately 60% VO2max. Each accommodation bout was separated by a 10-min rest. The 4th session assessed running economy. Subjects completed a 5-min warm-up at 2.68 m.s-1 followed by 10-min economy run at 2.68 m.s-1. RESULTS: Pearson product moment correlations revealed no significant correlations between running economy and flexibility measures. CONCLUSION: Results are in contrast to studies demonstrating an inverse relationship between trunk and/or lower limb flexibility and running economy in males. Furthermore, results are in contrast to studies reporting positive relationships between flexibility and running economy.     

Medical coverage for track and field events

Providing medical coverage at a track and field event is similar to other spectator events, but there are some important differences. With simultaneous events occurring over a large area, reliable communication with quick access to all event sites is mandatory. Preparation needs to include a prearranged emergency response plan for each event. Because field events involve throwing heavy and sometimes sharp objects (discus, hammer, shot put, and javelin) or landing in a cushioned pit (high jump, pole vault), sites need well-demarcated, constantly monitored boundaries with properly installed, well-maintained safety equipment. All personnel involved in monitoring these events should be educated on proper procedure in managing potential head or neck injuries. Event officials must also remained focused on their tasks, avoiding the distractions that simultaneous events can cause. Because most events are outdoors, appropriate protection and recovery sites for heat, cold, and sun exposure should be arranged.     

Muscle-specific creatine kinase gene polymorphism and running economy responses to an 18-week 5000-m training programme

Objective

To investigate the association between muscle‐specific creatine kinase (CKMM) gene polymorphism and the effects of endurance training on running economy.

Methods

102 biologically unrelated male volunteers from northern China performed a 5000‐m running programme, with an intensity of 95–105% ventilatory threshold. The protocol was undertaken three times per week and lasted for 18 weeks. Running economy indexes were determined by making the participants run on a treadmill before and after the protocol, and the A/G polymorphism in the 3′ untranslated region of CKMM was detected by polymerase chain reaction‐restricted fragment length polymorphism (NcoI restriction enzyme).

Results

Three expected genotypes for CKMM‐NcoI (AA, AG and GG) were observed in the participants. After training, all running economy indexes declined markedly. Change in steady‐state consumption of oxygen, change in steady‐state consumption of oxygen by mean body weight, change in steady‐state consumption of oxygen by mean lean body weight and change in ventilatory volume in AG groups were larger than those in AA and GG groups.

Conclusions

The findings indicate that the CKMM gene polymorphism may contribute to individual running economy responses to endurance training.The muscle‐specific creatine kinase (CKMM) enzyme is bound specifically to the M line of the myofibril subfragment,¹ one of the heavy meromyosin in the vicinity of the myosin ATPase and to the outer membrane and vesicles of the sarcoplasmic reticulum,² which might change the Ca²⁺ uptake³ and power of muscle. Type I (slow‐twitch) skeletal muscle fibres and type II (fast‐twitch) fibres have been shown to differ in their CKMM activities, with type I fibres showing at least a twofold lower CKMM activity.⁴ Skeletal muscles of athletes involved in endurance sports are characterised by a high proportion of type I fibres, as well as by high activity levels of marker enzymes of aerobic oxidative metabolism.⁵ Therefore, the lower activity of CKMM might be essential to endurance athletes.Running economy is typically defined as the energy demand for a given velocity of submaximal running, and is determined by measuring the steady‐state consumption of oxygen (VO₂) and the respiratory exchange ratio.⁶ Taking body mass into consideration, runners with good running economy use less energy and therefore less oxygen than runners with poor running economy at the same velocity.⁷ There is a strong association between running economy and distance running performance.^8,9,10The CKMM gene has been mapped to the q13.2–q13.3 region of chromosome 19.¹¹ Now, several lines of evidence suggest that the CKMM‐NcoI polymorphism in the 3′ untranslated region might contribute to the individual differences in VO₂max responses to endurance training.^12,13 Lucia et al,¹⁴ however, detected CKMM‐NcoI polymorphisms in 50 top‐level Spanish professional cyclists and 119 sedentary controls and found no significant differences for CKMM‐NcoI polymorphisms between athletes and controls. Recently, we found that the CKMM‐Nco polymorphism in the 3′ untranslated region was A/G variant by sequencing, and there were considerable differences in the allelic frequencies and genotypic frequencies between the Chinese Han population and those in Europe and America.¹⁵ Moreover, less is known about the association between CKMM‐NcoI polymorphism and individual running economy responses to endurance training. The purpose of this study, therefore, was to explore the potential relationship between the CKMM gene A/G polymorphism in Chinese and running economy responses to an 18‐week 5000‐m training programme.     

.VO2 kinetics during supramaximal exercise: relationship with oxygen deficit and 800-m running performance

The aim of this study was to compare .VO2 kinetics of highly- versus recreationally-trained subjects during a constant velocity test of supramaximal intensity. Eighteen trained male subjects were recruited to one of two groups: highly trained (HT, n = 8, .VO(2max) = 70.1 +/- 6.5 ml . min (-1) . kg (-1)) and recreationally trained (RT, n = 10, .VO(2max) = 63.2 +/- 6.4 ml . min (-1) . kg (-1)). All subjects performed an incremental test to exhaustion for the determination of .VO(2max) and peak treadmill velocity (PTV), two constant velocity tests at 110 % of PTV to determine .VO2 kinetics and oxygen deficit (O(2)def), and a 800-m time trial to determine running performance (mean velocity over the distance, V (800 m)). We found significant differences between HT and RT for the on-transient of the .VO2 response (tau, 24.7 +/- 3.3 and 30.9 +/- 7.0 s, respectively), the amplitude of the .VO2 response (60.0 +/- 5.0 and 53.5 +/- 5.7 ml . min (-1) . kg (-1), respectively) and V (800 m) (6.27 +/- 2.1 and 5.45 +/- 0.38 m . s (-1), respectively). O(2)def (24.6 +/- 2.7 and 27.7 +/- 7.8 ml . kg (-1), respectively) and the gain of the .VO2 response (193 +/- 14 and 194 +/- 13 ml . kg (-1) . m (-1), respectively) were similar between groups. tau was associated with O(2)def (r = 0.90, p < 0.05), but not with V (800 m) (r = 0.30, p > 0.05). It was concluded that HT subjects exhibited faster on-kinetics and higher amplitude than their RT counterparts. The higher amplitude was not thought to reflect any difference in underlying physiological mechanisms. The faster tau, whose exact mechanisms remain to be elucidated, may have practical implications for coaches.