Cycling-training evidence context¶
Preferred terminology for this platform. Definitions keep unlike measurements from being treated as synonyms. For evidence and application, use the topic index.
Performance and physiological boundaries¶
Maximal oxygen uptake (VO₂max): The greatest rate of whole-body oxygen uptake demonstrated during an appropriate maximal exercise test. Absolute uptake and body-mass-relative uptake answer different performance questions.
Fractional utilization: The fraction of VO₂max sustained during a specified task or at a specified physiological boundary. It is duration- and protocol-dependent, not one fixed percentage for an athlete.
First lactate or ventilatory threshold (LT1 / VT1): Operational estimates of the transition from the moderate to the heavy exercise-intensity domain. Lactate and ventilatory methods may disagree; a fixed blood-lactate concentration is not a universal individual threshold.
Second lactate or ventilatory threshold (LT2 / VT2): Method-dependent estimates of a higher-intensity physiological transition. They are not automatically interchangeable with critical power, maximal lactate steady state, or FTP.
Critical power (CP): The asymptote of an appropriately fitted power–duration relationship, used as an estimate of the heavy–severe intensity-domain boundary. Test selection, fitting method, and measurement error affect the estimate.
Maximal lactate steady state (MLSS): The highest tested constant workload meeting a stated blood-lactate stability criterion over a specified test duration. It is an operational laboratory measurement, not a synonym for CP.
Functional threshold power (FTP): A cycling performance estimate defined by the test or software used. A percentage of a 20-minute effort, a ramp-test estimate, and an actual sustained performance are different measurements. Avoid: using “FTP,” “LT2,” “CP,” and “MLSS” interchangeably.
W′: The curvature constant in a CP power–duration model, with units of work. It is not a direct measurement of a single anaerobic energy store, and estimates depend on the model and testing conditions.
Gross efficiency: External mechanical work divided by total metabolic energy expenditure during a specified workload. “Economy” denotes the metabolic cost of producing a specified output; the two measures are related but not identical.
Durability: The magnitude and timing of deterioration in physiological or performance characteristics during prolonged exercise. A fresh power–duration curve does not measure durability.
Training classification¶
Low-intensity endurance riding: Riding predominantly below the athlete's estimated LT1 / VT1, with sustainable breathing and low perceived exertion. It is research-model Zone 1 and often cycling-model Zone 2, but the mapping is not exact. Avoid: “Zone 2” without naming the zone model.
Three-zone research model: Zone 1 below LT1 / VT1; Zone 2 between first and second thresholds; Zone 3 above the second threshold. The chosen threshold methods must be stated.
Cycling power-zone model: A convention dividing power into five, six, or seven zones, commonly using percentages of FTP. Its numbered zones do not necessarily coincide with an athlete's physiological boundaries.
Training-intensity distribution: The allocation of training across defined intensity categories. Session-goal classification, time-in-zone, and distance-based classification are different counting methods.
Hard cycling session: A session with a substantial deliberate high-intensity, threshold, or race stimulus and a meaningful recovery cost. “Two hard days” does not mean two VO₂ sessions plus additional threshold workouts and races.
VO₂-focused intervals: Repeated work intended to stimulate maximal aerobic capacity and/or performance in the severe domain. Neither a fixed percentage of FTP nor breathlessness demonstrates that VO₂max was reached.
Sweet-spot training: A coaching category describing sustained work somewhat below an estimated FTP. It is not a uniquely validated physiological intensity domain or a proven universal stimulus-to-fatigue optimum.
Interpretation and recovery¶
Acute response: A physiological or performance response during or shortly after one exposure. Acute signaling or time near VO₂max is not proof of a subsequent training adaptation.
Longitudinal adaptation: A persistent change measured after repeated training exposures. A controlled intervention is needed to attribute a difference to a particular training prescription with confidence.
Evidence grade: A qualitative assessment of support for a precise conclusion in the relevant population. This platform uses Strong evidence, Moderate evidence, Plausible but uncertain, and Mostly coaching practice; these are not numerical scores or formal GRADE ratings.
Energy availability: Dietary energy remaining after exercise expenditure, considered relative to fat-free mass. Estimates are uncertain, and one calculated daily value or universal cutoff cannot diagnose relative energy deficiency in sport.
Relative energy deficiency in sport (RED-S): A clinical syndrome of impaired health and performance associated with problematic low energy availability. Assessment is individualized and extends beyond body weight or a single laboratory marker.
Plasma volume: The fluid component of circulating blood. Expansion can lower measured haemoglobin concentration without reducing total haemoglobin mass.
Haemoglobin mass: The total amount of circulating haemoglobin, distinct from its concentration in a blood sample. Plasma expansion alone does not demonstrate increased red-cell or haemoglobin mass.
Training-load model: A calculation summarizing selected training inputs, such as power, heart rate, or session RPE. Model outputs such as CTL are not direct measurements of fitness, recovery, or injury risk.