Acute Training Load (ATL): a quantitative metric intended to represent short-term training load; often interpreted synonymously with ‘fatigue’. ATL is calculated as a weighted average of the daily TSS (Training Stress Score) values over the last ~7 days (this period is modifiable).

Aerobic: with oxygen

Aerobic capacity: the maximum rate at which oxygen can be taken on and processed by the body to produce energy (i.e. ATP).

Aerobic system: the pathways through which the body is able to produce energy (i.e. ATP) using oxygen. This includes fat and carbohydrate oxidation, and to a very small degree, protein oxidation.

Anaerobic: without oxygen

Anaerobic capacity: the maximum rate at which energy can be produced through anaerobic systems.

Anaerobic stamina: the length of time a predominantly anaerobic effort can be maintained before fatigue.

Anaerobic system: the pathways through which the body is able to produce energy (i.e. ATP) without using oxygen. This includes the phosphocreatine system and anaerobic glycolysis.

ATL: see ‘Acute Training Load’.

ATP: stands for ‘adenosine triphosphate’, and is storage form of energy needed for muscular contraction (as well as a whole host of other energy-consuming processes in the body). You can think of ATP like a battery of energy, ready to be called upon when needed. All metabolic processes (such as the oxidation of fats and carbohydrates) work to resynthesize ATP stores.

Cadence: the pedalling speed, measured as the number of revolutions per minute (RPM).

Capillaries: small blood vessels that run close to tissues and organs (including, in particular, muscles) and facilitate the delivery of oxygen and nutrients (such as glucose) to the tissues and organs, and carry away waste and other products of metabolism (such as lactate and hydrogen ions).

Cardiac Output: The amount of blood pumped by the heart per minute (measured in litres per minute).

Central adaptations: Adaptations to the heart, lungs and blood which contribute to improved aerobic capacity (also known as VO2max). These include in particular, improved cardiac output, pulmonary diffusion, and haemoglobin content and concentration within the blood.

Chronic Training Load (CTL): A training metric intended to quantify long-term training load, and often interpreted as representing fitness level. It’s calculated as the average Training Stress Score (TSS) you’ve accumulated per day, with training carried out more recently given a greater weight in this calculation than training carried out further ago. The period over which the CTL is calculated can be adjusted, but is usually set to a period of 6 weeks.

CTL: See ‘Chronic Training Load’.

Economy: the amount of oxygen required to produce a given wattage.

Efficiency: the ratio of the work done on the bike (in kJ) relative to the energy required.

Endurance: the ability to sustain a predominantly aerobic power output for an extended period.

Form: the physical potential to perform well. It depends on both current fitness and fatigue levels.

Fractional utilisation: The location of the lactate threshold relative to aerobic capacity (or also known as VO2max). It can either be expressed as (i) the rate of oxygen consumption at the lactate threshold relative to VO2max or (ii) the power at the lactate threshold relative to the power at VO2max.

Functional Threshold Power: a field-based fitness measure that’s intended to approximate the lactate threshold power.

Glycogen: a storage form for carbohydrates within the body. It’s stored in both muscles and the liver, and is a major source of fuel during exercise.

Glycolysis: the anaerobic (without oxygen) break-down of carbohydrates to produce energy.

Glycolytic system: The system by which carbohydrates are broken down anaerobically (without oxygen) to produce energy.

Hydrogen ion: a by-product of glycolysis, which turns blood and muscles acidic and is thought to contribute to fatigue in high-intensity exercise.

Lactate: a by-product of glycolysis. Lactate itself is a useful by-product, which can be metabolised to produce additional energy. However, with each lactate ion produced, a hydrogen ion is also produced, which is thought to be linked with fatigue. This is the reason lactate has historically been considered as a negative product of glycolysis.

Lactate shuttling: the transport of lactate out of an active muscle fibre to other metabolically active tissues in the body, where it can then be oxidised.

Lactate threshold: the maximal exercise intensity that can be maintained while blood lactate concentration remains stable.

Macrocycle: a period of time between high-priority events or phases. Each macrocycle builds towards a specific target event or short series of events at which point you’re aiming to have peak form. They usually last at least 6 weeks, and are often several months long.

Mesocycle: A mesocycle is generally a block of more intensive training, followed by a recovery period. A mesocycle might be associated with specific training goals, which collectively work to achieve the overarching goals of the training phase in which the mesocycle falls.

Metabolism: The process by which the body converts substrates (e.g. fat and carbohydrates) into energy.

Microcycle: This is the smallest structure of training cycle. It’s often 7 days long and follows a regular pattern of training and recovery days, although this isn’t always the case.

Mitochondria: The part of the muscle cell where aerobic energy production takes place.

Muscle fibre: This is another name for a muscle cell. Muscle fibres are grouped into bundles of fibres, which collectively make up muscles.

Neuromuscular: This term refers to the system of nerves and muscles which collectively bring about muscle contraction. In this course, we typically use the term ‘neuromuscular to refer to aspects of training that impact the neural stimulation of muscles.

Peak anaerobic power: The maximum rate at which energy can be generated anaerobically. This includes both the phosphocreatine system, and the glycolytic system.

Periodisation: The concept that training differs at different times of the training cycle.

Phase: A period of training with a small number of specific training goals. Common examples are ‘base’ and ‘specific preparation’ phases. A phase can be as short as a couple of weeks, or might span several months.

Phosphocreatine system: The energy system which produces energy the fastest, but which is also depleted the fastest.

Rating of Perceived Exertion: see ‘RPE’.

RPE: Stands for ‘rating of perceived exertion’; an indicator of how hard a given exercise intensity feels.

Stroke volume: The amount of blood (in ml) pumped by the heart per beat.

Training Stress Balance (TSB): A training metric intended to quantify ‘form’. It’s quantified as the difference between the Chronic Training Load (CTL) and the Acute Training Load (ATL).

Training Stress Score (TSS): A training metric intended to quantify the amount of training stress accumulated through training. It depends on both the duration of the training, and the intensity of the training relative to Functional Threshold Power (FTP).

TSB: See ‘Training Stress Balance’.

TSS: See ‘Training Stress Score’.

Type I: A type of muscle fibre that’s extremely well adapted to aerobic metabolism. It’s good at producing power for long periods of time, but only at relatively low power outputs.

Type II: A type of muscle fibre that’s well adapted to anaerobic metabolism. There are actually two subtypes: Type IIa and Type IIx, where Type IIx are the most powerful fibres, and are almost exclusively anaerobic. Type IIa fibres sit between Type I and Type IIx, and have attributes that lend themselves both to aerobic and anaerobic metabolism; although they are generally most adapted for carbohydrate rather than fat metabolism.

VLamax: The maximal rate of lactate production, measured in mmol/L/sec. This is an indicator of the glycolytic capacity, or the maximal rate at which energy can be produced through glycolysis.

VO2max: See ‘Aerobic Capacity’.