Anaerobic Energy

Anaerobic energy

Althletic training for short burst exertions such as sprinting  inolves improving energy creation and expression in the first 1 or 2 minues of exertion. Muscle energy produce in this short burst depends on anaerobic combustion of fuel. In the second minute of exertion, aerobic metabolism takes over. With longer exrtions anaerobic processes averages in the range of 7-8% of the energy used in young men and women of moderate fitness level.

In a well-trained athlete, mechanical power output reaches its peak immediately after the beginning of exercise, then rapidly declines after 60 seconds.  The oxygen intake is small at the beginning, then rapidly increased to attain a steady state in 30 s at 80%-90% of the maximal O2 intake of the subject. Energy supplied  by  lactic acid reached its highest value during the period between 5 and 15 s, then rapidly decreased to nil in 60 s.

Course Work Abstracts:

Title Important determinants of anaerobic running performance in male athletes and non-athletes.

Author Nummela A; Mero A; Stray Gundersen J; Rusko H

Address Research Institute for Olympic Sports, Jyv?skyl?, Finland.

Source Int J Sports Med, 1996 Jul, 17 Suppl 2:, S91-6

Abstract The purpose of this study was to investigate the importance of selected metabolic and neuromuscular determinants as predictors of anaerobic running performance. The subjects were male 400-m runners (n = 21), middle- (n = 8) and long-distance runners (n = 11), power athletes (n = 14) and physically active men (n = 34). Maximal power (Pmax), peak blood lactate concentration (peak BLa), power at 10 mM blood lactate level (P10mM), height (CMJrest) and percentage decrease (CMJdecrease) of the counter-movement jump were determined by the maximal anaerobic running test (MART). In addition, maximal oxygen uptake (VO2max) was determined on a treadmill and maximal running velocity (V30m) was measured by the 30-m speed test on a track. Stepwise regression analysis revealed that V30m, P10mM and peak BLa accounted for 92% (P < 0.001) of the variation in Pmax. Regression analysis showed also that V30m, P10mM and delta P (the difference between Pmax and VO2max) were the most important determinants of the 400-m run on a track within a homogeneous group of 400-m runners. The middle-distance and 400-m runners had higher Pmax and P10mM than the long-distance and control group (p < 0.05). The 400-m runners had superior V30m and delta P than the other groups. Furthermore, the 400-m runners and power athletes had higher peak BLa than the long-distance and control group (p < 0.05). The present findings showed that V30m, P10mM and peak BLa determined by the 30-m speed test and the MART were the most important components of anaerobic work capacity. These determinants could be used to explain the differences in anaerobic work capacity between various sport groups as well as between different athletes.

Title The clinical importance of the anaerobic energy system and its assessment in human performance.

Author Cahill BR; Misner JE; Boileau RA

Address Orthopaedic Institute of Illinois, Peoria 61605, USA.

Source Am J Sports Med, 1997 Nov, 25:6, 863-72

Abstract The anaerobic energy system is involved in providing energy for all forms of physical activity. The relevance of this system to human performance and physical fitness throughout the age spectrum is underscored here and contrasted with the aerobic energy system. The anaerobic system responds to high-intensity training with biochemical, neural, and anatomic adaptations. Unlike the aerobic system, this response tends to be primarily a local phenomenon with little systemic adaptation. An important factor distinguishing anaerobic training from aerobic training is the intensity of the exercise dose. For anaerobic training to occur, the dose must be of high intensity and performed to near-exhaustion. The anaerobic system can be indirectly assessed by performance tests, such as a vertical jump or stair climb, or more directly by supramaximal bicycle tests. The impact of recent research regarding the trainability of the anaerobic system, particularly in the elderly population, is encouraging. The elderly respond to anaerobic training and, as a result, their independence, quality of life, and safety from falls can be improved. While little is known about anaerobic rehabilitation after injury, it is known that isokinetic and performance tests may be considered normal after rehabilitation, despite incomplete rehabilitation of the anaerobic system. Thus, appropriate application of the anaerobic system assessments and training principles is an important aspect of sports medicine practice.

Title One-mile run-walk performance in young men and women: role of anaerobic metabolism.

Author Sloniger MA; Cureton KJ; OBannon PJ

Address Department of Exercise Science, Ramsey Center, University of Georgia, Athens 30602-3654, USA.

Source Can J Appl Physiol, 1997 Aug, 22:4, 337-50

Abstract The aim of this study was to evaluate the importance of anaerobic metabolism as a determinant of individual differences in performance of a 1-mile run-walk (MRW). Anaerobic capacity, percentage of anaerobic capacity used during the MRW, percentage of energy used during the MRW that was supplied through anaerobic processes, aerobic metabolic determinants of distance running performance, and MRW time were measured in 26 male and 29 female young adult nonathletes. Anaerobic processes averaged 7-8% of the energy used during the MRW. In multiple regression analyses, anaerobic capacity, and a linear combination of all three anaerobic variables contributed significantly to the prediction of MRW with the effects of gender and VO2 peak held constant, but the additional variance accounted for by the anaerobic variables was relatively small (2-7%). In conclusion, anaerobic metabolism supplies only a small portion of the energy used during the MRW, and anaerobic capacity and metabolism during the MRW do not confound its interpretation as an indicator of maximal aerobic power in a heterogeneous group of young men and women of moderate fitness level.

A 3-parameter critical power model.

Author Morton RH

Source Ergonomics, 1996 Apr, 39:4, 611-9

Abstract The critical power test is a well-established procedure that provides estimates of two important parameters characterizing work performance; anaerobic work capacity (AWC) and critical power (CP). The concept proscribes a hyperbolic relationship between power output (P) and time to exhaustion (t), given by (P - CP)t = AWC. Since evidence now exists that the procedure overestimates CP and underestimates AWC, this study was undertaken to investigate the effect of relaxing the requirement that the time asymptote necessarily be at zero. Using data from a previous study, it is shown that in so doing, (1) a time asymptote significantly less than zero is obtained, (2) significantly smaller estimates of CP and larger estimates of AWC are obtained, (3) a third parameter is introduced that theoretically represents maximal instantaneous power, (4) it implies that the maximal power that could be developed at any instant is proportional to the amount of AWC remaining at that instant, which in turn implies that (5) at exhaustion not necessary all of AWC is consumed.

Title Effect of high intensity board training on upper body anaerobic capacity and short-lasting exercise performance.

Author Morton DP; Gastin PB

Address

Source Aust J Sci Med Sport, 1997 Mar, 29:1, 17-21

Abstract Seven conditioned post-pubescent male subjects (VO2peak = 2.8 +/- 0.1 l.min-1) performed three high intensity board training sessions per week for an eight week period, followed by ten days of reduced training (taper). Subjects performed a 60 second all-out test, on a Biokinetic swim bench ergometer, on five occasions throughout the duration of the study. Testing occurred pre-training (T1), during the third week of training (T2), during the sixth week of training (T3), following eight weeks of training (T4), and post-taper (T5). Performance parameters as well as oxygen deficit (OD) were recorded during the 60 second all-out tests for the assessment of anaerobic capacity. Time trials were completed at times corresponding to T1, T3 and T5 over distances of 75, 140 and 250 metres. Over the duration of the study improvements of 17 percent (p < 0.05) and 60 percent (p < 0.01) were observed for Biokinetic swim bench mean power and peak power, respectively. Improvements in mean power and OD reached significance after five weeks of training. Improvements of 11 (p < 0.05), seven (p < 0.05) and six (p < 0.05) percent were noted from pre-training to post-taper for the 75, 140 and 250 metre time trials, respectively. Peak oxygen uptake improved by five percent from pre-training to post-taper which was almost significant at the 0.05 level (p = 0.052). Mean power correlated significantly with the 75 (r = -0.74, p < 0.05) and 140 (r = -0.79, p < 0.05) metre time trials, indicating that in-water performance and Biokinetic swim bench ergometry are well related. The ten day period of reduced training had no effect on performance parameters assessed during the 60 second all-out tests. It was concluded that improvements in the anaerobic energy systems, and associated performance in short-lasting exercise of high intensity, can be induced within five weeks of high intensity training with no decrements in the aerobic energy system.

Title Physical and physiological factors associated with success in the triathlon.

Author Sleivert GG; Rowlands DS

Address School of Physical Education, University of Otago, Dunedin, New Zealand. gsleivert@pooka.otago.ac.nz

Source Sports Med, 1996 Jul, 22:1, 8-18

Abstract The physiological demands of sequential exercise in swimming, cycling and running are unique and require the triathlete to develop physical and physiological characteristics that are a blend of those seen in endurance swimming, cycling and running specialists. Elite triathletes are generally tall, of average to light weight and have low levels of body fat, a physique which provides the advantages of large leverage and an optimal power to surface area or weight ratio. Triathletes have high maximum oxygen uptake (VO2max) values, but VO2max may be on average marginally lower than values previously observed in endurance specialists. Although VO2max is a predictor of performance in triathletes of mixed abilities, it cannot be used to predict performance within homogenous groups of elite performers. Nevertheless, elite triathletes have significantly higher VO2max values than sub-elite triathletes and high VO2max levels are required for success in triathlons. The ability of the triathlete to exercise at a lower percentage of VO2max for a given submaximal workload may be especially important to triathlon success. This is influenced not only by VO2max itself, but also by anaerobic threshold and economy of movement. Anaerobic threshold, as indicated by either ventilatory threshold or lactate threshold, improves with triathlon training and when measured in the appropriate exercise mode has been related to swim, cycle and run performance in the triathlon. Economy of movement in swimming, cycling and running is also related to triathlon performance, and swimming economy in particular appears to be an area where triathletes could make large improvements. Future research should utilise experimental methodologies to investigate triathlon physiology, in particular, the influence of sequential exercise in different exercise modes on physiological function and examine the influence of different training interventions on triathlon physiology and performance.

 

Title The plasma lactate response to exercise and endurance performance: relationships in elite triathletes.

Author Hoogeveen AR; Schep G

Address Department of Sports Medicine, St Joseph Hospital, Veldhoven, The Netherlands.

Source Int J Sports Med, 1997 Oct, 18:7, 526-30

Abstract The lactate response to exercise has been studied thoroughly during the last decades and it has been described using a variety of terms and definitions. Numerous investigations observed close relationships between the lactate response and endurance performance. The main question in this study was which of the various lactate responses during incremental exercise described in the literature was the best indicator of endurance performance. The plasma lactate response (PLR) was assessed during an incremental exercise test on 13 male elite triathletes (age 25.5+/-5.8 yrs; HT 179.7+/-5.4 cm; WT 71.3+/-4.7 kg) on a bicycle ergometer. The load was started at 2.5 W/kg and increased by 40 W every 4 min. We evaluated the following PLR-parameters: the workloads at the fixed lactate levels of 2, 3, 4, 5, 6, 7, and 8 mmol/l which were assessed by extrapolation from a workload-lactate-heart rate curve (P2, P3, P4, P5, P6, P7, P8 respectively), the lactate threshold which was defined as the workload at the point at which a non-linear increase of blood lactate occurred (Plt), and the workload at the lactate level that was 1 mmol/l above the baseline (P + 1). Four to seven weeks after the laboratory test, heart rate and lactate levels were assessed during a 40-km long time trial on a bicycle. Two parameters were considered as indicative of athletic performance: the road racing time (Tt), and the workload extrapolated from the workload-lactate-heart rate curve at the heart rate and lactate levels observed during the time trial (Pt). Only P2 showed a significant correlation with Tt (r=-0.65; p < 0.05; se = 72.5 s). Multiple regression analysis with the anthropometric parameters height and weight as additional independent parameters did not change the predictive value. We concluded that for predicting the cycling performance of similarly well-trained subjects the predictive value of PLR is negligible.

 

Title Lactate exchange and removal abilities in rowing performance.

Author Messonnier L; Freund H; Bourdin M; Belli A; Lacour JR

Address Laboratoire de Physiologie-GIP Exercise, Facult? de M?decine, Oullins, France.

Source Med Sci Sports Exerc, 1997 Mar, 29:3, 396-401

Abstract The relationships between individual performance and lactate exchange and removal abilities were studies in 12 male rowers all subjected to three measurements on a rowing ergometer. An incremental exercise carried out to determine the maximal oxygen uptake (VO2max) and the corresponding maximal aerobic power (Pamax), a 2500-m all-out test where the mean work rate (P2500) represented the individual performance, and a 6-min 90% Pamax exercise designed to assess the lactate kinetics during the following 90 min passive recovery were performed. The lactate recovery curves were fitted to the bi-exponential time function: La(t) = La(O) + A1(1-e-gamma 1.t) + A2(1-e-gamma 2.t). The velocity constants gamma 1 and gamma 2 denote the lactate exchange and removal abilities, respectively. The mean value of P2500 sustained by the rowers was 376 +/- 41W (106 +/- 5% of Pamax (P2500%). P2500 was positively correlated with gamma 2 (P < 0.05). gamma 1 and gamma 2 explained 67% of the P2500 variance. P2500% was also correlated with gamma 2 (P < 0.01). These results suggest that a better performance on the rowing ergometer is associated with improved lactate exchange and removal abilities. Furthermore, the ability to row at high relative work rates was correlated with an increased lactate removal ability. Training-induced adaptations could explain the high gamma 1 and gamma 2 displayed by the present rowers.

Title Changes in plasma tryptophan/branched chain amino acid ratio in responses to training volume variation.

Author Tanaka H; West KA; Duncan GE; Bassett DR Jr

Address Exercise Science, University of Tennessee, Knoxville, USA.

Source Int J Sports Med, 1997 May, 18:4, 270-5

Abstract The major symptoms of overtraining including decreased exercise performance, altered mood states, and depleted muscle glycogen stores closely resemble the effects of brain serotonin, the level of which is dependent on the plasma ratio of tryptophan to branched-chain amino acids (BCAA). To examine the relation between plasma amino acids and overtraining, ten highly-trained endurance runners underwent two weeks of base training (normal training) before increasing their training volume by 40% for two weeks to achieve a state of short-term overtraining (or overreaching). The overtraining period was followed by two weeks of recovery in which training volume was reduced by 41% of the base training. For the whole group, no significant changes were observed in running economy and maximum oxygen uptake. There were no changes in resting heart rate, blood pressure, resting metabolic rate, and serum cortisol level in response to the changes in training volume. The runners experienced a significant increase (p < 0.05) in fatigue score for the profile of mood states when the training volume was increased. The elevated fatigue score returned to baseline when the training volume was reduced. Plasma free or total tryptophan, BCAA, and the tryptophan/BCAA ratio were not significantly altered throughout the course of this study. We concluded that proposed physiological markers of overtraining, including plasma tryptophan and BCAA levels, were unchanged despite a 40% increase in training volume.

Dangerous curves. A perspective on exercise, lactate, and the anaerobic threshold.

Author Myers J; Ashley E

Address Cardiology Division, Palo Alto Department of Veterans Affairs Medical Center, Stanford University, Calif, USA.

Source Chest, 1997 Mar, 111:3, 787-95

Abstract A number of general observations can be made from these recent studies. Lactate is a ubiquitous substance that is produced and removed from the body at all times, even at rest, both with and without the availability of oxygen. It is now recognized that lactate accumulates in the blood for several reasons, not just the fact that oxygen supply to the muscle is inadequate. Lactate production and removal is a continuous process; it is a change in the rate of one or the other that determines the blood lactate level. Rather than a specific threshold, there is most likely a period of time during which lactate production begins to exceed the body's capacity to remove it (through buffering or oxidation in other fibers). It may be appropriate to replace the term "anaerobic threshold" to a more functional description, since the muscles are never entirely anaerobic nor is there always a distinct threshold ("oxygen independent glycolysis" among others has been suggested)

 Lactate plays a major role as a metabolic substrate during exercise, is the preferred fuel for slow-twitch muscle fibers, and is a precursor for liver gluconeogenesis. The point at which lactate begins to accumulate in the blood, causing an increase in ventilation, is important to document clinically. Irrespective of the underlying mechanism or specific model that describes the process, the physiologic changes associated with lactate accumulation have significant import for cardiopulmonary performance. These include metabolic acidosis, impaired muscle contraction, hyperventilation, and altered oxygen kinetics, all of which contribute to an impaired capacity to perform work. Thus, any delay in the accumulation of blood lactate which can be attributed to an intervention (drug, exercise training, surgical, etc) may add important information concerning the efficacy of the intervention.

  A substantial body of evidence is available demonstrating that lactate accumulation occurs later (shifting to a higher percentage of Vo2max) after a period of endurance training. In athletes, the level of work that can be sustained prior to lactate accumulation, visually determined, is an accurate predictor of endurance performance. Presumably, these concepts have implications related to vocation/disability among patients with cardiovascular and pulmonary disease, but few such applied studies have been performed outside the laboratory. Blood lactate during exercise and its associated ventilatory changes maintain useful and interesting applications in both the clinical exercise laboratory and the sport sciences. However, the mechanism, interpretation, and application of these changes continue to rely more on tradition and convenience than science.

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