Effect of pre-existing high blood lactate concentration on maximal exercise performance

Identifying the Optimal Arm Priming Exercise Intensity to Improve Maximal Leg Sprint Cycling Performance

Priming exercises improve subsequent motor performance; however, their effectiveness may depend on the workload and involved body areas. The present study aimed to estimate the effects of leg and arm priming exercises performed at different intensities on maximal sprint cycling performance. Fourteen competitive male speed-skaters visited a lab eight times, where they underwent a body composition measurement, two V̇O_2max measurements (leg and arm ergometers), and five sprint cycling sessions after different priming exercise conditions. The five priming exercise conditions included 10-minute rest (Control); 10-minute arm ergometer exercise at 20% V̇O_2max (Arm 20%); 10-minute arm ergometer exercise at 70% V̇O_2max (Arm 70%); 1-min maximal arm ergometer exercise at 140% V̇O_2max (Arm 140%); and 10-min leg ergometer exercise at 70% V̇O_2max (Leg 70%). Power outputs of 60-s maximal sprint cycling, blood lactate concentration, heart rate, muscle and skin surface temperature, and rating of perceived exertion were compared between the priming conditions at different measurement points. Our results showed that the Leg 70% was the optimal priming exercise among our experimental conditions. Priming exercise with the Arm 70% also tended to improve subsequent motor performance, while Arm 20% and Arm 140% did not. Mild elevation in blood lactate concentration by arm priming exercise may improve the performance of high-intensity exercise.

Effect of Short-Duration High-Intensity Upper-Body Pre-Load Component on Performance among High-Level Cyclists

The aim of the present study was to evaluate the effects of upper-body high-intensity exercise priming on subsequent leg exercise performance. Specifically, to compare maximal 4000 m cycling performance with upper-body pre-load (MPThigh) and common warm-up (MPTlow). In this case, 15 high-level cyclists (23.3 ± 3.6 years; 181 ± 7 cm; 76.2 ± 10.0 kg; V˙O2max: 65.4 ± 6.7 mL·kg−1·min−1) participated in the study attending three laboratory sessions, completing an incremental test and both experimental protocols. In MPThigh, warm-up was added by a 25 s high-intensity all-out arm crank effort to the traditional 20-min aerobic warm-up. Both 4000 m maximal bouts started with a 12 s all-out start. Heart rate, blood lactate concentration [La) and spirometric data were measured and analyzed. Overall MPThigh time was slower by 5.3 ± 1.2 s (p < 0.05). [La] at the start was 5.5 ± 1.5 mmol·L−1 higher for MPThigh (p < 0.001) reducing anaerobic energy contribution which was higher in MPTlow during the first and third 1000 m split (p < 0.05). Similarly, MPTlow maintained higher total average power during the entire performance (p < 0.05, d = 0.7). Although the MPThigh condition performed less effectively due to decreased anaerobic capacity, pre-load effect may have the potential to enhance performance at longer distances.

The Effects of L-Citrulline on Blood-Lactate Removal Kinetics Following Maximal-Effort Exercise

The accumulation of lactate in muscle and blood during high-intensity exercise is negatively correlated with the duration exercise can be sustained. Removal of lactate is a key component of acute recovery between consecutive bouts of such exercise. Low-intensity exercise enhances recovery by accelerating lactate turnover in metabolically active tissues, largely mediated by blood flow to these tissues. Therefore, the purpose of this research was to clarify if L-citrulline, a nutritional supplement purported to promote vasodilation via enhanced nitric oxide availability, would augment the removal of blood lactate during active recovery (AR). L-citrulline ingestion will augment the rate of blood lactate concentration decrease during AR, reduce the oxygen-cost of submaximal exercise, and increase time-to-exhaustion and peak oxygen uptake (V̇O2peak) during a test of maximal aerobic power. Healthy university students (five males & five females) participated in this double-blind, randomized, placebo-controlled study. Participants exercised on a cycle ergometer at submaximal steady-state intensities followed by progressively increasing intensity to exhaustion, 10 min of AR, and then supramaximal intensity exercise to exhaustion. Oxygen uptake was measured throughout the trial and blood lactate was sampled repeatedly during AR. The protocol elicited very high peak blood lactate concentrations after exercise (11.3 + 1.3 mmol/L). L-citrulline supplementation did not significantly alter blood lactate kinetics during AR, the oxygen cost of exercise, V̇O2peak, or time-to-exhaustion. Despite a strong theoretical basis by which L-citrulline could augment lactate removal from the blood, L-citrulline supplementation showed no effect as an exercise-recovery supplement.

IRF4 in Skeletal Muscle Regulates Exercise Capacity via PTG/Glycogen Pathway

Exercise-induced fatigue and exhaustion are interesting areas for many researchers. Muscle glycogen is critical for physical performance. However, how glycogen metabolism is manipulated during exercise is not very clear. The aim here is to assess the impact of interferon regulatory factor 4 (IRF4) on skeletal muscle glycogen and subsequent regulation of exercise capacity. Skeletal muscle-specific IRF4 knockout mice show normal body weight and insulin sensitivity, but better exercise capacity and increased glycogen content with unaltered triglyceride levels compared to control mice on chow diet. In contrast, mice overexpression of IRF4 displays decreased exercise capacity and lower glycogen content. Mechanistically, IRF4 regulates glycogen-associated regulatory subunit protein targeting to glycogen (PTG) to manipulate glucose metabolism in skeletal muscle. Knockdown of PTG can reverse the effects imposed by the absence of IRF4 in vivo. These studies reveal a regulatory pathway including IRF4/PTG/glycogen synthesis on controlling exercise capacity.

Performance Enhancing Effect of Metabolic Pre-conditioning on Upper-Body Strength-Endurance Exercise

High systemic blood lactate (La) was shown to inhibit glycolysis and to increase oxidative metabolism in subsequent anaerobic exercise. Aim of this study was to examine the effect of a metabolic pre-conditioning (MPC) on net La increase and performance in subsequent pull-up exercise (PU). Nine trained students (age: 25.1 ± 1.9 years; BMI: 21.7 ± 1.4) performed PU on a horizontal bar with legs placed on a box (angular hanging) either without or with MPC in a randomized order. MPC was a 26.6 ± 2 s all out shuttle run. Each trial started with a 15-min warm-up phase. Time between MPC and PU was 8 min. Heart rate (HR) and gas exchange measures (VO₂, VCO₂, and VE) were monitored, La and glucose were measured at specific time points. Gas exchange measures were compared by area under the curve (AUC). In PU without MPC, La increased from 1.24 ± 0.4 to 6.4 ± 1.4 mmol⋅l^-1, whereas with MPC, PU started at 9.28 ± 1.98 mmol⋅l^-1 La which increased to 10.89 ± 2.13 mmol⋅l^-1. With MPC, net La accumulation was significantly reduced by 75.5% but performance was significantly increased by 1 rep (4%). Likewise, net oxygen uptake VO₂ (50% AUC), pulmonary ventilation (VE) (34% AUC), and carbon dioxide VCO₂ production (26% AUC) were significantly increased during PU but respiratory exchange ratio (RER) was significantly blunted during work and recovery. MPC inhibited glycolysis and increased oxidative metabolism and performance in subsequent anaerobic upper-body strength-endurance exercise.

Lactate metabolism: historical context, prior misinterpretations, and current understanding

Lactate (La^-) has long been at the center of controversy in research, clinical, and athletic settings. Since its discovery in 1780, La^- has often been erroneously viewed as simply a hypoxic waste product with multiple deleterious effects. Not until the 1980s, with the introduction of the cell-to-cell lactate shuttle did a paradigm shift in our understanding of the role of La^- in metabolism begin. The evidence for La^- as a major player in the coordination of whole-body metabolism has since grown rapidly. La^- is a readily combusted fuel that is shuttled throughout the body, and it is a potent signal for angiogenesis irrespective of oxygen tension. Despite this, many fundamental discoveries about La^- are still working their way into mainstream research, clinical care, and practice. The purpose of this review is to synthesize current understanding of La^- metabolism via an appraisal of its robust experimental history, particularly in exercise physiology. That La^- production increases during dysoxia is beyond debate, but this condition is the exception rather than the rule. Fluctuations in blood [La^-] in health and disease are not typically due to low oxygen tension, a principle first demonstrated with exercise and now understood to varying degrees across disciplines. From its role in coordinating whole-body metabolism as a fuel to its role as a signaling molecule in tumors, the study of La^- metabolism continues to expand and holds potential for multiple clinical applications. This review highlights La^-'s central role in metabolism and amplifies our understanding of past research.

The effects of compression garments and electrostimulation on athletes' muscle soreness and recovery

In this study, we explained the effects of compression garment and electrostimulation on athletes’ recovery period by evaluating blood lactate and isokinetic peak torque parameters. Twenty volunteers (15.55± 0.51 yr) were included to study. At recovery period, blood samples was taken for lactate values at 0th, 3rd, 5th, 15th, 30th min. The isokinetic strength test was performed on right ankle at 15th min and on the left ankle at 30th min. The same protocol was performed for compression garment on 2 weeks and for electrostimulation on third weeks and results were compared. There wasn’t any significant difference on blood lactate levels within groups. At women; there was not any significant difference on isokinetic peak torques within two groups. but at electro-stimulation usage we found significant increases on right plantar flexion (P<0.1), right dorsal flexion (RDF) (P<0.1) and left plantar flexion (LPF) (P<0.1) values compared to control measurements. At men; with compression garment usage, there was significant increase on LPF values compared to control measurements. At electrostimulation usage, we found significant increases on RDF (P<0.1) and left dorsal flexion (P<0.1) values compared to control measurements. During recovery, there is not any beneficial effect seen on blood lactate level within two groups. When compared to passive rest, compression garments and electrostimulation interventions effects on force generation capacity at recovery are statically significant. Also in terms of force generation capacity; usage of electrostimulation during 15 min and compression garments during 30 min were statically more significant.

Is lactate production related to muscular fatigue? A pedagogical proposition using empirical facts

The cause-effect relationship between lactic acid, acidosis, and muscle fatigue has been established in the literature. However, current experiments contradict this premise. Here, we describe an experiment developed by first-year university students planned to answer the following questions: 1) Which metabolic pathways of energy metabolism are responsible for meeting the high ATP demand during high-intensity intermittent exercise? 2) Which metabolic pathways are active during the pause, and how do they influence phosphocreatine synthesis? and 3) Is lactate production related to muscular fatigue? Along with these questions, students received a list of materials available for the experiment. In the classroom, they proposed two protocols of eight 30-m sprints at maximum speed, one protocol with pauses of 120 s and the other protocol with pauses of 20 s between sprints. Their performances were analyzed through the velocity registered by photocells. Blood lactate was analyzed before the first sprint and after the eighth sprint. Blood uric acid was analyzed before exercise and 15 and 60 min after exercises. When discussing the data, students concluded that phosphocreatine restoration is time dependent, and this fact influenced the steady level of performance in the protocol with pauses of 120 s compared with the performance decrease noted in the protocol with pauses of 20 s. As the blood lactate levels showed similar absolute increases after both exercises, the students concluded that lactate production is not related to the performance decrement. This activity allows students to integrate the understanding of muscular energy pathways and to reconsider a controversial concept with facts that challenge the universality of the hypothesis relating lactate production to muscular fatigue.

Effects of ephedrine, caffeine, and their combination on muscular endurance

PURPOSE

The purpose of this study was to investigate the effects of ingesting caffeine (C), ephedrine (E), and their combination on muscular endurance, using a double-blind, repeated measures design.

METHODS

Ninety minutes after ingesting either C (4 mg x kg-1), E (0.8 mg x kg-1), a combination of C+E, or a placebo (P), 13 male subjects performed a weight-training circuit consisting of three supersets (SS), each SS consisting of leg press (at 80% of 1 RM to exhaustion) followed by bench press (at 70% 1-RM to exhaustion); 2 min of rest intervened between SS.

RESULTS

The trials involving ephedrine ingestion (C+E and E), when compared with the nonephedrine trials (C and P), caused significant increases (P < 0.05) in the mean number of repetitions completed for both the leg-press and bench-press exercises but only during the first SS. During that first set, the mean number (+/-SD) of repetitions for leg press was 19 +/- 8, 16 +/- 7, 14 +/- 6, and 13 +/- 5 for the C+E, E, C, and P trials, respectively. The mean numbers of repetitions for the first set of bench-press exercise were 14 +/- 3, 13 +/- 3, 12 +/- 3, and 12 +/- 3 for the C+E, E, C, and P trials, respectively. As a result, the total weight lifted during all three sets was greater for the trials involving ephedrine ingestion. Systolic blood pressure before exercise was significantly increased with both ephedrine treatment trials when compared with the other trials (C+E = 156 +/- 29 mm Hg; E = 150 +/- 14; C = 141 +/- 16; P = 138 +/- 14).

CONCLUSION

It was concluded that acute ingestion of C+E and E increases muscular endurance during the first set of traditional resistance-training exercise. The performance enhancement was attributed primarily to the effects of E; there was no additive effect of C.

Effect of active and passive recovery on blood lactate and performance during simulated competition in high level gymnasts

The purpose of this study was to investigate the effect of two recovery strategies between men's gymnastics events on blood lactate removal (BL) and performance as rated by expert "blind" judges. Twelve male gymnasts (21.8 +/- 2.4 years) participated. The sessions were composed of routine performances in the six Olympic events, which were separated by 10 min of recovery. All gymnasts performed two recovery protocols between events on separate days: Rest protocol, 10 min rest in a sitting position; Combined protocol, 5 min rest and 5 min self-selected active recovery. Three blood samples were taken at 2, 5, and 10 min following each event. Gymnasts produced moderate values of BL following each of the six events (2.2 to 11.6 mmol.L-1). There was moderate variability in BL values between events that could not be accounted for by the athlete's event performance. Gymnasts showed higher BL concentration (p > .05) and significantly (p < .05) higher scoring performances (as rated by a panel of certified judges) when they used a combined recovery between gymnastics events rather than a passive recovery (delta BL = 40.51% vs. 28.76% of maximal BL, p < .05, and total score = 47.28 +/- 6.82 vs. 38.39 +/- 7.55, p < .05, respectively).

Effects of active recovery on plasma lactate and anaerobic power following repeated intensive exercise

The purpose of this study was to investigate the effects of active recovery (AR) on plasma lactate concentration [La] and anaerobic power output as measured during repeated bouts of intense exercise (6 s) against increasing braking forces. Ten male subjects performed two randomly assigned exercise trials: one with a 5-min passive recovery (PR) after each exercise bout and one with a 5-min active recovery (AR) at a workload corresponding to 32% of maximal aerobic power. Blood samples were taken at rest, at the end of each exercise bout (S1) and at the 5th minute between bout-recovery (S2) for plasma lactate assay. During the tests, [La]S1 was not significantly different after AR and PR, but [La]S2 was significantly lower after AR for power outputs obtained at braking forces 6 kg (5.66 +/- 0.38 vs 7.56 +/- 0.51 mmol.l-1) and peak anaerobic power (PAnP) (6.73 +/- 0.61 vs 8.54 +/- 0.89 mmol.l-1). Power outputs obtained at 2 and 4 kg did not differ after AR and PR. However, when compared with PR, AR induced a significant increase in both power outputs at 6 kg (842 +/- 35 vs 798 +/- 33 W) and PAnP (945 +/- 56 vs 883 +/- 58 W). These results showed that AR between bouts of intensive exercise decreased blood lactate concentration at high braking forces. This decrease was accompanied by higher anaerobic power outputs at these forces.

Strength and endurance characteristics of the normal human genioglossus

Since activity of the genioglossus muscle plays a primary role in maintaining upper airway patency during sleep, its strength and endurance characteristics are of potential importance. The purpose of this study was 2-fold. First, to define the strength and endurance characteristics of the normal human genioglossus. Second, we hypothesized that because the genioglossus has a high proportion of fast glycolytic muscle fibers, brief periods of increased activity would make it more susceptible to fatigue. In five normal male subjects strength of the tongue was evaluated by measuring maximal anterior force using a transducer (Fmax). In each subject tongue endurance was then tested at 100%, 80%, and 50% Fmax. To test the effect of a short-term increase in genioglossal activity on its endurance, an inspiratory flow-resistive load with mild hypercapnia was presented to the upper airway for 10 min, after which genioglossal endurance at 80% Fmax was repeated. On a separate day the effect of inspiratory loading plus hypercapnia on thoracic inspiratory muscle endurance was also tested. Our results showed that mean Fmax was 1,267 +/- 125 (SEM) g. Endurance time (Tlim) decreased progressively during 50%, 80% and 100% Fmax trials. Short-term activation of the genioglossus caused a reduction in Tlim at 80% Fmax to 51.4 +/- 4.8% of its value before loading (p < 0.05). Tlim for the inspiratory muscles, however, was unaffected. We conclude that, like other skeletal muscles, genioglossal endurance is reduced as the force of contraction increases. In addition, genioglossal endurance is significantly reduced by short-term activation insufficient to fatigue the thoracic inspiratory muscles.

Effects of recovery duration and blood lactate level on power output during cycling

This study identifies the quickest recovery between consecutive anaerobic tests to maintain power output (PO) on the repeated test. Sixteen male cyclists finished three sessions of max rpm initial and repeated 45-s cycling tests at 53.9 N. Tests were separated by 6, 9, or 12 min of recovery cycling (80 rpm, 9.8 N). Results showed no significant differences in PO between initial tests (M = 578.5 +/- 50 watts). PO was significantly less on the 6-min repeated test (M = 551.2 +/- 51) compared to the 9- (M = 575.1 +/- 53) and 12-min tests (M = 581.7 +/- 49.9) (p > 0.05). Net blood lactate [HLa] (repeated test-recovery) was significantly related to net PO (repeated test-initial test) on the 9- (r = 0.60, p < 0.05) and 12-min (r = 0.64, p < 0.001) trials, but not on the 6-min trial (r = 0.35, p = 0.19). In summary, at least 9 min of recovery cycling maintains PO on a repeated 45-s cycling test. Elevated [HLa] at the onset of high-intensity sprint exercise is moderately associated with PO on repeated cycle ergometer tests.

The effects of caffeine on graded exercise performance in caffeine naive versus habituated subjects

The physiological effects of caffeine on subjects habituated to caffeine is relatively unstudied compared to those of caffeine naive subjects during graded exercise. Thus, the purpose of this investigation was to determine the effects of caffeine on maximal oxygen consumption (VO2max) and the anaerobic threshold in these two populations. Seventeen moderately trained males were classified according to caffeine usage: (1) caffeine consumption 25 mg.day-1 or less (CN) (n = 8) or (2) caffeine consumption above 300 mg.day-1 (CH) (n = 9). The subjects were tested post-absorptive on the same cycle ergometer on three occasions with 7 days separating the tests. One hour before each test the subject ingested either a gelatin capsule (C); 3 mg.kg-1 body weight of caffeine (C3); or 5 mg.kg-1 body weight of caffeine (C5). The subject then performed an incremental VO2max test beginning at 50 W and the work rate was increased 30 W every 2 min until the subject could not maintain the power output. Serial venous blood samples were drawn over 30 s at the end of each stage. The CN group significantly increased resting heart rate (fc) and expired ventilation volume (VE) after C3 and C5 and VO2 after C5. No significant differences were found for exercise VE, VO2, respiratory exchange ratio, fc or time to exhaustion. There were no significant differences (P less than 0.05) in the lactate threshold or the ventilatory threshold between treatment in either group. The CH subjects showed a significant increase (P less than 0.05) in resting plasma free fatty acid (FFA) concentration only during the C3 and C5 treatments.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of previous severe exercise upon the respiratory Vco2/Vo2 exchange ratio as a predictor of maximum oxygen uptake

The present study examined the effect of previous severe exercise upon (i) respiratory exchange during maximal exercise, and (ii) the respiratory Vco2/Vo2 exchange ratio (R) as a predictor of maximum oxygen uptake (Vo2max). Thirteen healthy males performed a progressive treadmill test to Vo2max: at rest (T1); after a 1 h run on the level treadmill at a speed corresponding 82.4 +/- 7.3% of their Vo2max (T2); after 1 h recovery (T3); and after 24 h recovery (T4). Respiratory gases were continuously monitored. No changes in average work Vo2, Vo2max or maximum heart rate were found between trials. Average work Vco2 was lower in T2 (2.055 +/- 0.093 1.min-1, p less than 0.001), T3 (2.080 +/- 0.087 1.min-1, p less than 0.001) and T4 (2.337 +/- 0.154 1.min-1, NS) compared with T1 (2.360 +/- 0.147 1.min-1). This resulted in lower average R values in T2 (0.81 +/- 0.02, p less than 0.001), T3 (0.83 +/- 0.02, p less than 0.001) and T4 (0.94 +/- 0.02, NS) in relation to T1 (0.95 +/- 0.02). Analysis of the %Vo2max/R relationship over the final 5 min of each test showed a shift to the left during T2 (p less than 0.001), T3 (p less than 0.001) and T4 (NS) compared with T1. As a result predictions of Vo2max based on R (Vo2max/R) were similar to recorded Vo2max in T1 (+ 0.6%) and T4 (+ 2.2%). But higher in T2 (+ 8.7%, p less than 0.001) and T3 (+ 6.9%, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Blood lactate. Implications for training and sports performance

The blood lactate response to exercise has interested physiologists for over fifty years, but has more recently become as routine a variable to measure in many exercise laboratories as is heart rate. This rising popularity is probably due to: the ease of sampling and improved accuracy afforded by recently developed micro-assay methods and/or automated lactate analysers; and the predictive and evaluative power associated with the lactate response to exercise. Several studies suggest that the strong relationship between exercise performance and lactate-related variables can be attributed to a reflection by lactate during exercise of not only the functional capacity of the central circulatory apparati to transport oxygen to exercising muscles, but also the peripheral capacity of the musculature to utilise this oxygen. For example, several studies contrast the relationship between VO2max and endurance running performance with that between a lactate variable and the same running performance. In every study, the lactate variable is more highly correlated with performance. Similarly, prescribing training intensity as a function of the lactate concentration elicited by the training may prove to be a means of obtaining a more homogeneous adaptation to training in a group of athletes or subjects than is obtained by setting intensity as a function of maximal heart rate or % VO2max. A review of the recent literature shows that the lactate response to supramaximal exercise is a sensitive indicator of adaptation to 'sprint training' and is correlated with supramaximal exercise performance. This review also describes the possible applications of lactate measurements to enhance the rate of recovery from high intensity exercise. Although the lactate response to exercise is reproducible under standardised conditions it can be influenced by the site of blood sampling, ambient temperature, changes in the body's acid-base balance prior to exercise, prior exercise, dietary manipulations, or pharmacological interpretation.

Effects of caffeine ingestion on metabolism and performance during graded exercise

Seven trained men were studied during graded cycle ergometer exercise to assess the effects of caffeine ingestion on metabolism and performance. A single blind experimental procedure was followed with one trial being performed 60 min after the subject ingested caffeine (5 mg . kg-1) while the second trial required the subject to ingest a placebo with the treatment order being counterbalanced. Subjects began exercising at a work load of 30 W while the load was increased by an additional 30 W every 3 min until the subject could not maintain the desired pedal frequency. Venous blood samples were obtained at each work load and assayed for free fatty acids (FFA), glycerol, lactic acid, and caffeine. There was no significant difference (p greater than 0.05) in time to exhaustion between the two experimental treatments. Resting measurements of FFA and glycerol showed that ingestion of caffeine brought about significant (p less than 0.05) increases in plasma levels of both FFA and glycerol compared to values obtained during the placebo treatment. The rate of blood lactic acid accumulation was not significantly different (p greater than 0.05) between the two exercise tests. These data suggest that a small dose of caffeine does not change the rate of blood lactate accumulation nor does it enhance performance during graded cycle ergometer exercise.

Effects of prolonged warm-up exercise above and below anaerobic threshold on maximal performance

The purpose of the present study was to determine the effects of prolonged warm-up exercise above and below anaerobic threshold (AT) on maximal performance. Warm-up exercise consisted of pedalling the Monark cycle ergometer at either 40% (Below AT) or 68% (Above AT) of VO2max for 60 min. Each maximal performance consisted of two 40 s bouts of "all out" pedalling on the Monark cycle ergometer against 5.5 kg resistance separated by a 5 min rest period. These tests were administered on two occasions without warm-up exercise and were found to be reproducible for work output and peak blood lactate concentration. Below AT warm-up exercise significantly increased core temperature with no increase in steady state blood lactate concentration and was thus representative of a desired warmed-up status. This condition did not contribute to an improved maximal performance. Above AT warm-up exercise resulted in significant increases in core temperature and steady state blood lactate concentration. Work output and peak blood lactate concentration for maximal exercise were significantly decreased. It was concluded that task specific prolonged warm-up exercise below AT does not contribute to an improved maximal performance of the type employed in the present study. Following warm-up exercise above AT, maximal performance was impaired. This was attributed to probable glycogen depletion in fast twitch muscle fibers which in turn may have contributed to a decreased lactate production.

The effects of various warming up intensities and durations during a short maximal anaerobic exercise

In the literature, few experiments deal with the study of warming up before short exercises. The present paper investigates the influence of different warming up procedures on a short maximal anaerobic exercise leading to exhaustion in 1 min or less. Performance, heart rate, oxygen consumption, and lactic acid level are measured. The performance is improved when light warming up (30% VO2 max) is used just before the criterion exercise, while it is impaired with a more strenuous warming up (70% VO2 max). After light warming up, heart rate and oxygen consumption are slightly higher during the criterion exercise as compared with the values without warming up. Warming up itself does not lead to an increase in lactic acid level. When a resting period is introduced between warming up and exercise, no modification occurs whatever the warming up intensity, and no important variation of the physiological measures are observed in this case.