Differences in the duration of each stage and the load increments can alter the cardiorespiratory and metabolic response, and therefore the measurement Bentley et al. As suggested by pioneering studies Buchfuhrer et al. This is critical because MAS is a pertinent and widespread criterion to set training intensities for endurance disciplines Billat and Koralsztein, ; Jones and Carter, However, the validity and reliability of GXT with 1-min stages protocol in runners needs to be fully verified.
Physiological response to exercise in endurance sports is commonly assessed though measurements based on ventilatory and lactate methods. Recent findings support the idea that a training model based on ventilatory thresholds VT 1 and VT 2 could be very effective to set individual exercise intensity in endurance sports given that it takes into account individual metabolic responses Wolpern et al.
In turn, in VT 2 , the blood lactate accumulation boosts and rises considerably and the system collapses due to the homeostatic compromise and metabolic acidosis Wasserman et al.
However, gas exchange systems require the use of expensive equipment and laboratory conditions which most teams, coaches, and athletes are not equipped with or cannot afford. A further method to set individual exercise intensity is based on capillary blood lactate CBL measurements Beneke et al. A number of authors have defined a list of CBL parameters associated with specific exercise intensities such as LT Wasserman et al.
An accurate detection of MLSS is particularly important due to it being considered the highest intensity in which glycogen stores are the main exercise limiting factor Coyle et al. Although CBL methods are commonly used for coaches to set individual training workloads, the relationship between lactate-based parameters and VTs load intensities is still an open debate. However, the estimation of VT 2 from lactate methods generates some controversy.
To the best of our knowledge, there are no previous studies examining these relationships in runners. This is an important gap considering the existing differences between cycling and running, such as the more impaired ventilation in cycling and the higher muscle mass involved, greater muscle pump efficiency, and the implication of eccentric muscle actions in running Bijker et al.
Given that these differences may alter the physiological response to exercise, prescribing training plans for runners based on cyclists' reference values could be imprecise. In addition to the aerobic—anaerobic transition, another ventilation parameter to predict running performance is the MAS McLaughlin et al. As stated above, a valid alternative to these field tests is to determine the MAS through GXT with 1-min increments using gas exchange systems.
However, this hypothesis is still to be proven. Therefore, the aims of this study were 1 to establish the best fit between ventilatory and lactate exercise performance parameters in running and 2 to explore novel alternatives to estimate essential running performance indicators such as the MAS from similar intensity parameters like the V peak when gas exchange systems are not available.
Twenty-two trained male athletes runners and triathletes volunteered to participate in this study age All participants were competing at regional and national level races and following a regular training load of 4—6 days per week, 1—2 h per day. Measurements were obtained during the pre-competitive season. All participants underwent a complete medical examination including ECG that showed all were in good health. No physical limitations or musculoskeletal injuries that could affect testing procedures were reported.
None of the subjects were taking drugs, medications, or dietary supplements known to influence physical performance. The Bioethics Commission of the University of Murcia approved the study, which was carried out according to the declaration of Helsinki. Subjects were verbally informed about the experimental procedures and possible risk and benefits.
Written informed consent was obtained from all subjects. Participants visited the lab 5—7 times separated by 2—7 days. All participants had at least 6 months of familiarization with the testing procedures used in this investigation.
Lastly, athletes came back to the lab two to three more times to perform a 30 min submaximal constant running test to determine the speed associated with the MLSS Beneke, Training sessions were repeated each 48 h with 24 h rest before each evaluation to ensure a full recovery.
Air ventilation was controlled with a fan positioned 1. The V peak was automatically obtained from the treadmill software using the Kuipers et al. Capillary blood lactate samples from the finger were collected Lactate Pro, Arkray, Japan every 2 min i. In particular, fingerprint blood samples were collected by a specialist placed beside the treadmill without any pause during the participants' running test i.
If verified, physiological parameters were determined, and the individuals' treadmill speed at each of the physiological parameters studied were considered for subsequent analysis.
Blood lactate analyzer and indirect calorimetry devices were calibrated before each test according to the manufacturer's instructions.
Depending on the results of the first MLSS - test, successive trials with a h rest between sessions were increased or decreased 0. V peak was taken from the highest velocity reached during this GXT protocol and calculated according to the Kuipers et al. Figure 1. Each gas-exchange data point corresponds to a 5-s interval. Baseline CBL was the average during the initial stages with values 0.
This always occurred just before the curvilinear increase in blood lactate observed at subsequent exercise intensities Coyle et al. D MAX method was determined by plotting the lactate response to exercise intensity in a third-order polynomial regression curve. D MAX was defined as the point on the regression curve that yields the maximal distance to the straight line formed by the two end points of the curve Cheng et al. Two independent observers detected all ventilatory and LT following the criteria previously described.
The reliability of ventilation and lactate parameters was analyzed comparing the consistence among trials i. Analyses were performed using GraphPad Prism 6. I added one to his list — FTP. Note that not everyone in the field of sport science will agree with me on each of these.
Scientists can — and do — argue about how many angels can dance on the head of a pin. When exercise moves from the lab to the real world, precision is nearly always compromised.
In the lab almost everything is tightly controlled so precise definitions are also necessary. In the real world weather, traffic, hills, stoplights, safety and scores of other variables crowd out much of the precision. Aerobic threshold AeT. This is a relatively low level of intensity marked by light breathing and the feeling that you could maintain the effort for a few hours.
A ballpark way of determining your aerobic threshold is to subtract 30 beats per minute from your lactate threshold see below heart rate. The fact is that there is still plenty of confusion regarding lactate, and what lactate threshold represents. Lactate is a great unknown in human metabolism, despite its key role in its regulation. For many years it has been thought that lactate was just a waste product as a result of anaerobic exercise.
Lactate studies date back from the 19th century, when Nobel Laureate Louis Pasteur proposed that lactate was produced by lack of oxygen during muscle contraction. Another Nobel Laureate, Otto Meyerhof proposed that glycogen was a precursor of lactate. He also observed that muscle contraction produced lactate and loss of excitability. George Brooks, a metabolism expert from the University of California at Berkeley, has studied lactate extensively for more than 40 years.
Most of what we know about lactate is thanks to his work. We know now that lactate formation can occur under aerobic conditions, and that lactate production is the result of glucose utilization by muscle cells under aerobic conditions. In fact, it is the most important gluconeogenic precursor new glucose generator in the body.
Lactate is also a key regulator of intermediary metabolism, regulating substrate utilization. It decreases and inhibits the breakdown of fat for energy purposes lipolysis , as well as the rate of glucose utilization by cells glucolysis. Believe it or not, lactate is even crucial for the brain, being the main fuel that neurons use. Some studies show that when lactate uptake by neurons is suppressed, long-term memory is inhibited. Lactate could also be involved in some chronic metabolic diseases like type 2 diabetes.
Blood lactate levels in this population are times higher than in healthy physically active population. Cancer cells have a disrupted metabolism utilizing too much glucose aerobically Warburg effect and producing large amounts of lactate which could contribute to tumor growth and progression.
Clearly, lactate is not just a waste product of anaerobic exercise. It is a major fuel and a key regulator of metabolism. Lactate is the byproduct of glucose utilization by muscle cells.
The higher the glucose flux into the cell, the higher the lactate production—iundependently of oxygen availability. What is the anaerobic threshold and why should you care? What is anaerobic threshold? What does anaerobic threshold feel like? Aerobic Vs. Read next. Heart Rate Training Data.
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