Exercise & Physical Training

Aerobic capacity is the maximum rate of oxygen uptake the body can sustain to produce ATP via oxidative metabolism during prolonged exercise. Per the Fick principle (VO2 = Q ×…

Anabolic resistance is the age-associated blunting of muscle protein synthesis (MPS) in response to protein ingestion and resistance exercise. In young adults, roughly 20–25 g of…

The anaerobic threshold (AT) is the exercise intensity above which aerobic metabolism can no longer meet ATP demand and lactate begins to accumulate at a rate exceeding…

Blood flow restriction (BFR) training applies a pneumatic cuff or elastic wrap proximally to a limb to partially occlude venous return while preserving arterial inflow, enabling…

Bone mineral density is the amount of mineral — primarily hydroxyapatite — per unit area (g/cm²) or volume of bone tissue, most commonly assessed at the lumbar spine and femoral…

Cardiac output (Q) is the volume of blood the heart ejects per minute: heart rate (HR, beats/min) × stroke volume (SV, mL/beat). At rest Q is 4–6 L/min, rising to 20–25 L/min in…

Cardiorespiratory fitness (CRF) is the ability of the circulatory and respiratory systems to deliver oxygen to working muscles during sustained activity, most often quantified by…

The interference effect describes the attenuation of resistance-training adaptations - strength, power, and especially hypertrophy - when endurance training is performed…

Critical power (CP) is a theoretically derived aerobic metabolic ceiling: the highest sustainable power output (or running speed, as critical velocity) below which a finite work…

Daily step count is the total number of walking steps accumulated in a 24-hour period, measured by accelerometer-based pedometers or wearable devices detecting vertical…

Detraining is the partial or complete reversal of training-induced physiological adaptations that occurs when exercise is reduced or stopped. The rate and magnitude of reversal…

Dual-energy X-ray absorptiometry (DEXA) measures body composition and bone mineral density by directing two X-ray beams at different energy levels through tissue and quantifying…

Dynapenia is the age-related loss of muscle strength and power that occurs independently of muscle mass loss. The term was coined by Clark and Manini (2008) to distinguish…

Eccentric training emphasizes the lengthening phase of a muscle contraction, such as the lowering portion of a squat or curl. Muscles produce greater force eccentrically than…

EPOC is the elevated oxygen uptake that persists after exercise ends, as the body restores ATP and creatine phosphate, clears lactate, refills oxygen stores, and returns hormones…

Grip strength is the maximal force generated when squeezing a dynamometer and serves as a low-cost proxy for whole-body muscular function. In the 17-country PURE cohort (Leong et…

Heart rate recovery (HRR) is the drop in heart rate during the first minute (HRR1) or two minutes (HRR2) after stopping peak or symptom-limited exercise testing. Mechanistically…

HIIT alternates short bouts of near-maximal effort with periods of low-intensity recovery, typically over 10–30 minutes total. The high-intensity intervals stress cardiac output…

Isometric training involves contracting muscles against an immovable resistance without joint movement, as in planks, wall sits, or holding a mid-range squat. It builds tendon…

Lactate threshold is used loosely for two points: LT1 (aerobic threshold, ~2 mmol/L), where blood lactate first rises above baseline, and LT2, the highest intensity sustainable…

Maximum heart rate (HRmax) is the highest beats per minute the heart reaches during all-out exertion. It is largely determined by age and genetics, not fitness, and declines with…

The metabolic equivalent of task (MET) is a unit that expresses the energy cost of a physical activity as a multiple of resting metabolic rate, with 1 MET defined as the oxygen…

Mitochondrial density refers to the number and volume of mitochondria per unit of muscle tissue. Higher density expands oxidative capacity, allowing more fatty acids and pyruvate…

Mitochondrial respiratory capacity is the maximal rate of oxygen flux through the electron transport chain (ETC) under substrate-saturating, ADP-saturating conditions, distinct…

Muscle protein synthesis (MPS) is the anabolic process by which skeletal muscle cells assemble new proteins from amino acids, driving muscle maintenance, repair, and hypertrophy.…

NEAT is the energy expended during all daily activity outside of structured exercise — walking, standing, fidgeting, household chores, and posture maintenance. It can vary by up…

The one-repetition maximum (1RM) is the greatest load that can be lifted through a full range of motion for a given exercise in a single maximal effort with proper form, serving…

Plyometrics are explosive movements — jumps, hops, bounds, throws — that exploit the stretch-shortening cycle, in which a rapid eccentric load primes a powerful concentric…

Progressive overload is the principle of gradually increasing training demands — load, volume, density, range of motion, or proximity to failure — to keep driving adaptation.…

Rate of force development (RFD) is the change in muscle force per unit time (N/s), quantifying how rapidly maximal force can be expressed — a key component of muscular power…

Resting heart rate (RHR) is the number of heartbeats per minute at full rest, ideally measured supine after several minutes of quiet rest or upon waking, and is influenced by…

Reps in Reserve (RIR) is an autoregulation method for prescribing and grading resistance-training intensity by asking the lifter to estimate how many additional repetitions could…

Sarcopenia is the age-related loss of skeletal muscle mass, strength, and function; contributing factors include anabolic resistance, neuromuscular changes, chronic inflammation,…

Sarcopenic obesity is the concurrent presence of low skeletal muscle mass or function (sarcopenia) and excess adiposity. The combination is more adverse than either condition…

Satellite cells are tissue-resident muscle stem cells lying quiescent between the sarcolemma and the basal lamina of mature skeletal muscle fibers, identifiable by Pax7…

The sit-rise test measures the ability to lower oneself to the floor and stand back up using as little support as possible, scored from zero to ten with points deducted for hand,…

Strength training is structured exercise that loads muscles against resistance — free weights, machines, bands, or bodyweight — to drive neural adaptation and muscle protein…

Stroke volume is the quantity of blood ejected by the left ventricle per heartbeat — approximately 60–100 ml at rest in healthy adults and 150–200 ml or more in elite endurance…

Tendon stiffness is the mechanical property describing how much force a tendon transmits per unit of elongation (ΔForce/ΔLength, typically reported in N/mm); the related material…

Skeletal muscle fibers are broadly classified into Type I (slow-oxidative) and Type II (fast-glycolytic and fast-oxidative-glycolytic) on the basis of myosin heavy chain isoform…

Visceral adipose tissue (VAT) is the metabolically active fat depot surrounding the intra-abdominal organs, distinct from subcutaneous adipose tissue. VAT adipocytes drain into…

VO2max is the maximum rate of oxygen consumption during intense exercise, typically expressed in mL/kg/min. Per the Fick principle, it reflects oxygen delivery (cardiac output,…

Zone 2 training is sustained aerobic exercise at or just below the first lactate threshold (LT1, ~1.5–2.0 mmol/L), often roughly 60–70% of max heart rate, though the precise…